explain xkcd - User contributions [en]

Talk:2602: Linguistics Degree

2022-04-06T05:02:02Z

Yosei:

I think i messed up with the file upload- i was trying to help, sorry guys! [[User:Mushrooms|Mushrooms]] ([[User talk:Mushrooms|talk]]) 07:00, 5 April 2022 (UTC)
:I think I fixed it. We use the small version of the file, not the x2. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:47, 5 April 2022 (UTC)

Not to be too nit-picky, but the legendary animal is a combination of jackrabbit and antelope, no jackal in it, therefore it’s jackelope. [[Special:Contributions/172.70.126.65|172.70.126.65]] 07:18, 5 April 2022 (UTC)
: Uh, no. It's "jackalope": Google is your friend. [[Special:Contributions/172.70.130.153|172.70.130.153]] 09:51, 5 April 2022 (UTC)
::Yes, I saw the wiki article. Either the person who coined the word was an idiot who thought it was spelled “antalope” or didn’t know how to make a portmanteau. Either way, it is NOT a portmanteau of jackrabbit and antelope, because that would be jackralope or jackelope. At best, you can call it a portmanteau of jackrabbit and a _misspelling_ of antelope.[[Special:Contributions/172.70.126.87|172.70.126.87]] 17:44, 5 April 2022 (UTC)
::: Excuse me? Are you in charge of "Jackalope" or Ponytail? ;) [[User:Lexi|Lexi]] ([[User talk:Lexi|talk]]) 20:36, 5 April 2022 (UTC)

My immediate reaction to this was to see where ///bassoon.jackalope.slurp (What3words) took me. Nowhere - but suggested ///passion.jackpot.slurps is near Chausserais, 100 km ESE of Nantes in central France.[[User:Jmbryant|Jmbryant]] ([[User talk:Jmbryant|talk]]) 10:22, 5 April 2022 (UTC)
:That's nearer {{w|Dahu}}-country, though! [[Special:Contributions/172.70.86.64|172.70.86.64]] 10:38, 5 April 2022 (UTC) (P.S. Not that this is even a valid example why, but I rather think What3words is a bad development that will do more harm than good in serious navigation/geolocating purposes. Just sayin' in passing.)

:In some languages, a bassoon is called ''fagotto'' i.e. faggot, which in English is an offensive word addressing a male homosexual person (Note: I'm describing the word, not discriminating against any people). The word ''jack'' also means a male person, and an antelope is '''horny'''. With ''slurp'', these three words happen to be kind of '''inappropriate''' or '''graphic''', if seen this way. Maybe? Thoughts? [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 05:02, 6 April 2022 (UTC)

Could the random student in Ohio be a cousin of the random programmer in Nebraska? --[[User:Quazgar|Quazgar]] ([[User talk:Quazgar|talk]]) 11:53, 5 April 2022 (UTC)

There's a Linguistics Society of America, maybe they could coordinate the assignment of words to graduates. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 13:44, 5 April 2022 (UTC)
:In the US, yes. In most of the rest of the world follows ISO 1806. [[Special:Contributions/172.70.130.153|172.70.130.153]] 16:43, 5 April 2022 (UTC)
::ISO 1806 Determination of mesh breaking force of netting? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:55, 5 April 2022 (UTC)

Cueball's objection to "slurp" is not explained; what's wrong with "slurp"? I think it's great word! (I wonder if trades are allowed...) [[Special:Contributions/172.68.146.81|172.68.146.81]] 21:31, 5 April 2022 (UTC) Corin
:You're right. The word ''slurp'' is just a word, value-neutral. What this word means can be seen variously, though. In some countries, slurping (e.g. noodle) is not only culturally acceptable but possibly seen positively, implying what they're eating is delicious. In some other countries, slurping may be a no-no, seen negatively. Some webmasters may not like the Yahoo Slurp bot, as it might misbehave. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 05:02, 6 April 2022 (UTC)

I wonder if those who graduated with honors are entrusted with more difficult words, like irregular verbs or ones with tricky homophones. [[Special:Contributions/172.70.38.41|172.70.38.41]] 01:21, 6 April 2022 (UTC)
:[https://imgflip.com/i/16xi7j Or both..]? ;) [[Special:Contributions/172.70.85.177|172.70.85.177]] 02:37, 6 April 2022 (UTC)

Talk:2599: Spacecraft Debris Odds Ratio

2022-03-29T11:38:08Z

Yosei:

correct me if i'm wrong, but i believe 300 - 30 is 270, not 280? [[Special:Contributions/172.68.50.85|172.68.50.85]] 22:50, 28 March 2022 (UTC)
:something something percentage points maybe? idk [[Special:Contributions/172.70.134.91|172.70.134.91]] 22:56, 28 March 2022 (UTC)Bumpf
:Most likely there is an unstated chance of death by not going outside... presumably ~10% but there's no way to know the breakdown (could be nearly all cardio, could be nearly all ursine if they live in a cave next bears) [[Special:Contributions/172.69.70.127|172.69.70.127]] 23:02, 28 March 2022 (UTC)
::300% increase is multiplying by (1+3), 30% decrease is multiplying by (1-0.3) , %increases are multiplicative so the increase is by a factor of 4*0.7=2.8, which is 280% of the original value (or a 180% increase). {{unsigned ip|162.158.146.69}}
:::Yeah, barring a total mistake, that must be where the number came from, but it seems odd by the inconsistent way it is expressed, as it assumes the 300% increase for the bear attack is added to the initial value for a final amount of 400%, along with a similar treatment for the 30% decrease, but the 280% is simply the final value skipping past that step to the conclusion afterwards that is not even shown for the previous numbers. But with the improper grammar, if it's not an actual typo, it may be trying to show the speaker acting dumb or irrational, as it doesn't make sense to end with "increased" instead of "increase" without changing part of the words before that number. Someone thinking that poorly though likely wouldn't be able to multiply things properly to produce that 280% number though.--[[Special:Contributions/172.70.130.153|172.70.130.153]] 01:13, 29 March 2022 (UTC)
::::Someone who do understand this method of getting to 280% should add that to the explanation. I'm not quite sure what is meant here above, so an even better explanation would be preferable. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 08:28, 29 March 2022 (UTC)
:::Joke proof: ''Assume'' that every year 400 people are killed by bears in the world, of which 100 are killed inside and 300 are killed outside. Then, indeed, by going outside, the probability that you will be killed by bears increases from 100 to 300: that is 300%. On the other hand, we know that walking outside every day will reduce your risk of death from cardiovascular disease by 30%. Therefore, by walking outside properly, 30% of the above-mentioned 400 people, i.e. 120 people, could in theory avoid death from the said disease, ''if'' not attacked by bears. This implies that, even if everyone in the world walked outside every day, only 120 out of the 400 bear attack victims would be potentially saved, while 280 would die anyway. Since by hypothesis only 100 are killed inside by bear attacks, going outside will clearly increase the probability of deadly bear attacks, from 100 to 280: that is 280%. —[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 09:52, 29 March 2022 (UTC)
:::As said above, 300% increase and 30% decrease gives a factor ×2.8 which is a +180% increase (not 280%) [[Special:Contributions/162.158.50.176|162.158.50.176]] 10:38, 29 March 2022 (UTC)
::::It's a joke :) Since the title text is obviously a joke, maybe we shouldn't over-analyze it, except we can enjoy ourselves by “analyzing” it half-jokingly. Seriously, though, there is also some ambiguity in a natural language itself: e.g. by “one-and-a-half times larger than”, one may mean “one-and-a-half times as large as” (150%), or one may mean “150% larger than” (250%). When spoken informally, this kind of ambiguity is not uncommon. Another example would be “five hundred one thousandths” which may mean 501/1000 or 500/1000. Take it easy & take care :) — [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 11:38, 29 March 2022 (UTC)

"That's a 280% increased" has a typo/grammaro. The last word should be "increase". [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 23:04, 28 March 2022 (UTC)
:I think the actual typo is the "a" so should be "That's 280% increased" {{unsigned ip|162.158.146.69}}

Also what's an odds ratio?? ~~Bumpf {{unsigned ip|172.70.38.41}}
:I assume something like "million to one". But the units of the horizontal axis clearly don't correspond to that. I don't know what those units are, they're not a percentage, either. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:40, 29 March 2022 (UTC)
:: if you say "this is 4 times as likely" then "4" is the "odds ratio", this is the type of number appearing on the horizontal axis {{unsigned ip|162.158.146.69}}
:An odds-ratio is a way of reporting the results for predictions of binary outcomes. It's a transformation of the (not easily interpretable) regression coefficient. For example, if the OR for "males" (vs females) is "0.70", they're 70% as likely to have the outcome as females; if it's "1.32", then males are 1.32x as likely (equivalently: 32% more likely) to have that outcome as females. [[Special:Contributions/108.162.249.75|108.162.249.75]] Gye Greene

Did something happen to the size of the image after the initial posting? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:40, 29 March 2022 (UTC)

What's with the asterisks on the right side? [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 00:50, 29 March 2022 (UTC)
:I think the asterisks denote that the value at this range is "significant" because its error bars do not overlap with the baseline. If you stay outdoors 5 hours or more in a day, there is a nonzero chance that you will be hit by flying space debris. [[User:Laura|Laura]] ([[User talk:Laura|talk]]) 08:15, 29 March 2022 (UTC)

There should probably be an explanation of what "Monte Carlo Simulation" means, as many people who would actually want an explanation of this strip would likely be unfamiliar with that term.--[[Special:Contributions/172.70.131.122|172.70.131.122]] 01:02, 29 March 2022 (UTC)
:Yes, exactly! I got as far as finding {{w|Monte Carlo method}} via a redirect but have no idea how the bars are supposed to work, what the reference point is supposed to mean, or why the columns get skinnier toward the right. Not dumb, but next to no statistics education. [[User:Yngvadottir|Yngvadottir]] ([[User talk:Yngvadottir|talk]]) 07:51, 29 March 2022 (UTC)

::Yes, I added some links to try to make the graph a little more explore-friendly for folks willing to click and read what's beyond, but I don't have the smarts to really explain it. [[User:Laura|Laura]] ([[User talk:Laura|talk]]) 08:00, 29 March 2022 (UTC)

Why is the x-axis of the chart in logarithmic spacing? Any particular reason for this, or is it part of the joke? [[User:Captain Nemo|Captain Nemo]] ([[User talk:Captain Nemo|talk]]) 09:29, 29 March 2022 (UTC)

==Odds ratio confusion?==
I am very confused by the X axis of this comic, I feel like I must be misunderstanding how this works, but I thought I understood how odds ratios worked. Maybe not.
The graph "reads" that "In the reference situation, with zero hours spent outside, the odds ratio for head injuries from falling spacecraft debris is 1.0 ± 0." A 1.0 odds ratio means 1.0:1.0, or that either possibility is 50% likely. That is, there's an even chance your head will be injured by spacecraft debris or that it will not, ''if you stay indoors.'' That does not seem like it could be right, so can someone point me to my error? Thanks! [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 09:34, 29 March 2022 (UTC)
:As best I can tell, this is taking odds as a ratio between ''any'' two events. Rather than the usual "success : failure" (or "happens : doesn't happen"), it's "this scenario happens : control scenario happens". By definition, the control scenario is set at 1.0, and something at a ratio of (say) 2.0 is twice as likely to happen. -- [[User:Peregrine|Peregrine]] ([[User talk:Peregrine|talk]]) 10:50, 29 March 2022 (UTC)

1724: Proofs

2022-03-29T10:05:55Z

Yosei: /* Explanation */ prove and disprove -> prove or disprove

{{comic
| number = 1724
| date = August 24, 2016
| title = Proofs
| image = proofs.png
| titletext = Next, let's assume the decision of whether to take the Axiom of Choice is made by a deterministic process ...
}}

==Explanation==
[[Miss Lenhart]] is teaching a math class. She begins a proof when one of her students ([[Cueball]]) interrupts her asking if this is one of those dark-magic (unclear, incomprehensible) proofs. She claims no, but in a matter of seconds Cueball is calling out that he was right.

The proof she starts setting up resembles a {{w|proof by contradiction}}. However, after Cueball's interruption Miss Lenhart's proof takes a turn for the absurd: rather than assuming there will be a point in the function that correlates to co-ordinates (x, y), Miss Lenhart assumes that the ''act of writing numbers on the board'' will correlate to co-ordinates (x, y).

A ''normal'' proof by contradiction begins by assuming that a particular condition is true; by demonstrating the implications of this assumption, a logical contradiction is reached, thus disproving the initial assumption. One example of a proof by contradiction is the proof that √2 is an irrational number:

# Assume that √2 is a rational number, meaning that there exists a pair of integers whose ratio is √2.
# If the two integers have a common factor, it can be eliminated using the Euclidean algorithm.
# Then √2 can be written as an irreducible fraction ''a''/''b'' such that ''a'' and ''b'' are coprime integers (having no common factors other than 1).
# The equation ''a''/''b'' {{=}} √2, when multiplied by itself, gives ''a²''/''b²'' {{=}} 2, which can be rearranged as ''a²'' {{=}} 2''b²''.
# Therefore, ''a²'' is even because it is equal to 2''b²''. (2''b²'' is necessarily even because it is 2 times another whole number, and multiples of 2 are even.)
# It follows that ''a'' must be even (as squares of odd integers are never even).
# Because ''a'' is even, there exists an integer ''k'' that fulfills: ''a'' {{=}} 2''k''.
# Substituting 2''k'' from step 7 for ''a'' in the second equation of step 4: 2''b²'' {{=}} (2''k'')''²'' is equivalent to 2''b²'' {{=}} 4''k²'', which is equivalent to ''b²'' {{=}} 2''k²''.
# Because 2''k²'' is divisible by two and therefore even, and because 2''k²'' {{=}} ''b²'', it follows that ''b²'' is also even, which means that ''b'' is even.
# By steps 6 and 9, ''a'' and ''b'' are both even, which contradicts that ''a''/''b'' is irreducible as stated in step 3.
::'''''Q.E.D.'''''

Alternatively, instead of a proof by contradiction the setup could be for a one way function. For example, it is relatively easy to test that a solution to a differential equation is valid but choosing the correct solution to test can seem like black magic to students.

The way that Ms Lenhart's proof refers to the act of doing math itself, is characteristic of metamathematical proofs, for example {{w|Gödel's incompleteness theorems}}, which, at first sight, may indeed look like black magic, even if in the end they must be a "perfectly sensible chain of reasoning" like the rest of good mathematics. While typical mathematical theorems and their proofs deal with such mathematical objects as numbers, functions, points or lines, the metamathematical theorems treat other theorems as objects of interest. In this way you can propose and prove theorems about possibility of proving other theorems. For example, in 1931 {{w|Kurt Gödel}} was able to prove that any mathematical system based on arithmetics (that is using numbers) has statements that are true, but can be neither proved nor disproved. This kind of metamathematical reasoning is especially useful in {{w|set theory}}, where many statements become impossible to prove or disprove if the {{w|axiom of choice}} is not taken as a part of the axiomatic system.

Using a position on the blackboard as a part of the proof is a joke, but it bears a resemblance to {{w|Cantor's diagonal argument}} where a position in a sequence of digits of a real number was a tool in a proof that not all infinite sets have the same {{w|cardinality}} (rough equivalent of the number of elements). This "diagonal method" is also often used in metamathematical proofs.

The axiom of choice itself states that for every collection of nonempty sets, you can have a function that draws one element from each set of the collection. This axiom, once considered controversial, was added relatively late to the axiomatic set theory, and even contemporary mathematicians still study which theorems really require its inclusion. In the title text the decision of whether to take the axiom of choice is made by a deterministic process, that is a process which future states can be developed with no randomness involved. {{w|Determinacy}} of infinite games is used as a tool in the set theory, however the deterministic process is rather a term of the {{w|stochastic process|stochastic processes theory}}, and the {{w|dynamical systems theory}}, branches of mathematics far from the abstract set theory, which makes the proof even more exotic. The axiom of choice was mentioned earlier in [[804: Pumpkin Carving]] and later in [[982: Set Theory]], another comic about a math class with a similar theme on how teachers teach their student mathematical proofs.

Although Miss Lenhart did retire a year ago after [[1519: Venus]], she seems to have returned here for a math course at university level, but continues the trend she finished with in her prior class. A very similar Miss Lenhart comic was later released with [[2028: Complex Numbers]].

==Transcript==
:[Miss Lenhart is standing facing left in front of a whiteboard writing on it. Eleven left aligned lines of writing is shown as unreadable scribbles. A voice interrupts her from off-panel right.]
:Miss Lenhart: ... Let's assume there exists some function ''F''(''a,b,c''...) which produces the correct answer-
:Cueball (off-panel): Hang on.

:[In a frame-less panel Cueball is sitting on a chair at a desk with a pen in his hand taking notes.]
:Cueball: This is going to be one of those weird, dark magic proofs, isn't it? I can tell.

:[Miss Lenhart has turned right towards Cueball, who is again speaking off-panel. The white board is also off-panel.]
:Miss Lenhart: What? No, no, it's a perfectly sensible chain of reasoning.
:Cueball (off-panel): All right...

:[Miss Lenhart is facing the whiteboard again writing more scribbles behind some of the lines from before (the first line has disappeared). The lines that have more text added are now number three and five (four and six before). Cueball again speaks off-panel.]
:Miss Lenhart: Now, let's assume that the correct answer will eventually be written on the board at the coordinates (''x, y''). If we—
:Cueball (off-panel): I ''knew'' it!

{{comic discussion}}

[[Category:Comics featuring Miss Lenhart]]
[[Category:Comics featuring Cueball]]
[[Category:Math]]

Talk:2599: Spacecraft Debris Odds Ratio

2022-03-29T09:52:59Z

Yosei: '280%' joke proof

correct me if i'm wrong, but i believe 300 - 30 is 270, not 280? [[Special:Contributions/172.68.50.85|172.68.50.85]] 22:50, 28 March 2022 (UTC)
:something something percentage points maybe? idk [[Special:Contributions/172.70.134.91|172.70.134.91]] 22:56, 28 March 2022 (UTC)Bumpf
:Most likely there is an unstated chance of death by not going outside... presumably ~10% but there's no way to know the breakdown (could be nearly all cardio, could be nearly all ursine if they live in a cave next bears) [[Special:Contributions/172.69.70.127|172.69.70.127]] 23:02, 28 March 2022 (UTC)
::300% increase is multiplying by (1+3), 30% decrease is multiplying by (1-0.3) , %increases are multiplicative so the increase is by a factor of 4*0.7=2.8, which is 280% of the original value (or a 180% increase). {{unsigned ip|162.158.146.69}}
:::Yeah, barring a total mistake, that must be where the number came from, but it seems odd by the inconsistent way it is expressed, as it assumes the 300% increase for the bear attack is added to the initial value for a final amount of 400%, along with a similar treatment for the 30% decrease, but the 280% is simply the final value skipping past that step to the conclusion afterwards that is not even shown for the previous numbers. But with the improper grammar, if it's not an actual typo, it may be trying to show the speaker acting dumb or irrational, as it doesn't make sense to end with "increased" instead of "increase" without changing part of the words before that number. Someone thinking that poorly though likely wouldn't be able to multiply things properly to produce that 280% number though.--[[Special:Contributions/172.70.130.153|172.70.130.153]] 01:13, 29 March 2022 (UTC)
::::Someone who do understand this method of getting to 280% should add that to the explanation. I'm not quite sure what is meant here above, so an even better explanation would be preferable. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 08:28, 29 March 2022 (UTC)
:::Joke proof: ''Assume'' that every year 400 people are killed by bears in the world, of which 100 are killed inside and 300 are killed outside. Then, indeed, by going outside, the probability that you will be killed by bears increases from 100 to 300: that is 300%. On the other hand, we know that walking outside every day will reduce your risk of death from cardiovascular disease by 30%. Therefore, by walking outside properly, 30% of the above-mentioned 400 people, i.e. 120 people, could in theory avoid death from the said disease, ''if'' not attacked by bears. This implies that, even if everyone in the world walked outside every day, only 120 out of the 400 bear attack victims would be potentially saved, while 280 would die anyway. Since by hypothesis only 100 are killed inside by bear attacks, going outside will clearly increase the probability of deadly bear attacks, from 100 to 280: that is 280%. —[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 09:52, 29 March 2022 (UTC)

"That's a 280% increased" has a typo/grammaro. The last word should be "increase". [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 23:04, 28 March 2022 (UTC)
:I think the actual typo is the "a" so should be "That's 280% increased" {{unsigned ip|162.158.146.69}}

Also what's an odds ratio?? ~~Bumpf {{unsigned ip|172.70.38.41}}
:I assume something like "million to one". But the units of the horizontal axis clearly don't correspond to that. I don't know what those units are, they're not a percentage, either. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:40, 29 March 2022 (UTC)
:: if you say "this is 4 times as likely" then "4" is the "odds ratio", this is the type of number appearing on the horizontal axis {{unsigned ip|162.158.146.69}}
:An odds-ratio is a way of reporting the results for predictions of binary outcomes. It's a transformation of the (not easily interpretable) regression coefficient. For example, if the OR for "males" (vs females) is "0.70", they're 70% as likely to have the outcome as females; if it's "1.32", then males are 1.32x as likely (equivalently: 32% more likely) to have that outcome as females. [[Special:Contributions/108.162.249.75|108.162.249.75]] Gye Greene

Did something happen to the size of the image after the initial posting? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:40, 29 March 2022 (UTC)

What's with the asterisks on the right side? [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 00:50, 29 March 2022 (UTC)
:I think the asterisks denote that the value at this range is "significant" because its error bars do not overlap with the baseline. If you stay outdoors 5 hours or more in a day, there is a nonzero chance that you will be hit by flying space debris. [[User:Laura|Laura]] ([[User talk:Laura|talk]]) 08:15, 29 March 2022 (UTC)

There should probably be an explanation of what "Monte Carlo Simulation" means, as many people who would actually want an explanation of this strip would likely be unfamiliar with that term.--[[Special:Contributions/172.70.131.122|172.70.131.122]] 01:02, 29 March 2022 (UTC)
:Yes, exactly! I got as far as finding {{w|Monte Carlo method}} via a redirect but have no idea how the bars are supposed to work, what the reference point is supposed to mean, or why the columns get skinnier toward the right. Not dumb, but next to no statistics education. [[User:Yngvadottir|Yngvadottir]] ([[User talk:Yngvadottir|talk]]) 07:51, 29 March 2022 (UTC)

::Yes, I added some links to try to make the graph a little more explore-friendly for folks willing to click and read what's beyond, but I don't have the smarts to really explain it. [[User:Laura|Laura]] ([[User talk:Laura|talk]]) 08:00, 29 March 2022 (UTC)

Why is the x-axis of the chart in logarithmic spacing? Any particular reason for this, or is it part of the joke? [[User:Captain Nemo|Captain Nemo]] ([[User talk:Captain Nemo|talk]]) 09:29, 29 March 2022 (UTC)

==Odds ratio confusion?==
I am very confused by the X axis of this comic, I feel like I must be misunderstanding how this works, but I thought I understood how odds ratios worked. Maybe not.
The graph "reads" that "In the reference situation, with zero hours spent outside, the odds ratio for head injuries from falling spacecraft debris is 1.0 ± 0." A 1.0 odds ratio means 1.0:1.0, or that either possibility is 50% likely. That is, there's an even chance your head will be injured by spacecraft debris or that it will not, ''if you stay indoors.'' That does not seem like it could be right, so can someone point me to my error? Thanks! [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 09:34, 29 March 2022 (UTC)

2586: Greek Letters

2022-03-24T01:11:06Z

Yosei: /* Greek letters */

{{comic
| number = 2586
| date = February 25, 2022
| title = Greek Letters
| image = greek_letters.png
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.
}}

==Explanation==
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. The text for each letter should be in the explanation with an attempt at explaining it. This has not been included and many of the letters have no explanation of the given text, only for what they actually are used for. Do NOT delete this tag too soon.}}
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. This comic gives a (non-)explanation of what they typically mean, see [[#Greek letters|below]].

In the title text the joke about capital Xi from the main comic is continued. In the main comic those using Ξ (capital xi) greets us as Earth mathematicians, indicating they are not from Earth, but have come here to learn what we know of math. In the title text the idea that any one using Ξ must be aliens is made clear. So if you ever meet someone using this letter while doing math, then learn as much as you can by quietly observing them, before they return to their home planet. Either learn from their possible advanced math (that allowed them to construct a way to get from one star system to another), or learn about them as the aliens species they represent.

Previously [[Randall]] made a similar comic, [[2520: Symbols]], about math symbols.

===Greek letters===

* '''π (lowercase pi): This math is either very simple or impossible.''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). In a common school curriculum, this constant first shows up in introductory geometry classes, which would be considered "simple" by advanced mathematicians. But often, pi can show up seemingly randomly in advanced equations that have nothing to do with a circle at first glance, such as in infinite series. And because pi is transcendental, it can sometimes be difficult to work with pi in those situations. The comic may also be a reference to the impossibility of squaring the circle.
* An alternate explanation is that the comic refers to how the symbol can sometimes be used as a variable where the 'p' sound might make sense, such as in the prime-counting function where it stands for "prime" or the Buckingham π theorem where it stands for "parameter." These uses can be confusing to students who have only ever seen a lowercase pi used for the circle constant. This has pushed college courses to use it less and less frequently for anything other than the circle constant, so that now you are only likely to see π as something else in higher math. (More confusing still is the variant lowercase pi, so-called omega pi {{w|Pi_(letter)#Variant_pi|ϖ}} sometimes used for angular frequency instead of the more common (and very similar-looking) lowercase omega ω. In astronomy, ϖ is traditionally used to denote the {{w|Longitude of the periapsis|longitude of perihelion}}.)

* '''Δ (capital delta): Something has changed.''' — Typically prefixes a variable to refer to a macroscopic change in or finite difference of that variable. For instance, Δ'''v''' may be the finite change in velocity '''v''' over some finite time span, while Δ[''f''](''x'') represents the forward difference of ''f'' at ''x'', defined as Δ[''f''](''x'') = ''f''(''x''+1) - ''f''(''x'').

* '''δ (lowercase delta): Something has changed and it's a mathematician's fault.''' — Used in calculus. In many areas of maths we study systems by introducing small changes (perturbations) in input variables and observing how the system changes. The perturbations introduced are often written down as ''x'' → ''x'' + ''δx'' for some variable ''x'' we're perturbing, where ''δx'' is the change we've introduced. These are often applied in physics (perturbation theory, principle of least action, Noether's theorem,…). Since this change was purposefully introduced by the mathematician instead of occurring naturally, it is therefore their fault.

* '''θ (lowercase theta): Circles!''' — Used in trigonometry. Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based. In European handwriting, the variant form ϑ is commonly used with the same meaning.

* '''φ (lowercase phi): ''ORBS''''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. Lowercase phi has two forms in modern typography which are confused by this website's default font. In the comic, it has a complete circle with a vertical line passing through it, which is what Knuth called "phi." The alternate form, ϕ, is what Knuth called "variant phi" and can be written in a single stroke. Most fonts reverse the way these symbols are rendered. There is no difference in meaning between the symbols. Additionally, "O R B S" is written with spaces between each letter, possibly a reference to the linguistic phenomena of surreal memes and their tendency to add spaces between letters of "surreal-sounding" words like "orbs".

* '''ϵ (lowercase epsilon): Not important, don't worry about it.''' — Typically used to refer to a very small quantity. ϵ may be an error term in a statistical model (which is usually small if the model is useful), a remainder term in an approximation (same), or an arbitrarily small (positive) quantity in analysis. Although a total cumulative change of "ϵ" is negligible, in analysis, ϵ is most often applied in a context of an infinitesimal change occurring with infinite frequency. The study of ratios of quantities that approach zero gives rise to infinitesimal calculus. Also used for a sequence of transfinite numbers that are unreachable from ω by finite application of addition, multiplication, and exponentiation. This Greek lowercase letter has two common modern variants, ϵ and ε. ϵ is called the "{{w|Epsilon#Unicode|lunate epsilon}}" and may be more common in the U.S. A stylized version (∈) is used as the mathematical symbol for "is an element of." ε is what Knuth called the "variant epsilon" and is never used for the "element of" symbol but otherwise has identical meaning. Because epsilon represents an arbitrarily small (positive) quantity, there's no reason for anyone to worry about it from a practical standpoint. Also used in set theory to show a number is part of a set, e.g. X ϵ Y (x is part of set Y).

* '''υ,ν (lowercase upsilon and nu): Is that a v or a u? Or...oh no, it's one of ''those''.''' — Common in college level physics and engineering equations. ν commonly represents wavenumber in physics as well as a wide variety of other variables, often with names starting in N (e.g. neutron) or V (e.g. viscosity). Lowercase upsilon is rarely used, probably to avoid confusion. The symbols look remarkably similar to Latin u and v, to the point that they are nearly indistinguishable in some fonts; Randall has complained about this before in [[2351: Standard Model Changes]].

* '''μ (lowercase mu): This math is cool but it's not about anything that you will ever see or touch, so whatever.''' — Used broadly in the abstract mathematical fields of category theory and measure theory. Also used in statistics for mean (average). Physicists use Latin letters for the indices of the 3-vectors of classical physics and Greek indices, including μ, for the 4-vectors of special relativity. This leads to μ being ubiquitous in a field which is very far from everyday experience (where speeds approach the speed of light). It is also employed in statistics for the population mean, which is a quantity that the statistician never actually knows and frequently wants to estimate. Equations requiring a μ are thus impossible to apply directly. However, μ is used in physics for the coefficient of friction in the Coulomb model, typically used to approximate resistive forces between dry solids of different material sliding past each other. A very common use of μ in science and engineering is as the symbol of the SI prefix ''micro-'' for a millionth. Unicode has officially added a point for μ as the "micro sign," distinct from its usual codepoint as the lowercase Greek letter mu.

* '''Σ (capital sigma): Thank you for purchasing ''Addition Pro''®!''' — Typically used as a symbol for the sum of a series of numbers. The comic is making fun of summation, pointing out that it's essentially a complicated, "pro" version of simple addition. The capital sigma is often used as the icon for the all-important "sum" button in spreadsheet software. However, the sigma operator is often necessary for explicitly defining infinite sums, avoiding ambiguous notation like an ellipsis (...).

* '''Π (capital pi): ...and the ''Multiplication''® expansion pack!''' — Typically used as a symbol for the product of a sequence of numbers. The joke is the same as for summation. Here, it is advertised as an "expansion pack," a term used for a piece of software that cannot stand alone but adds features to some existing software. Any paid spreadsheet or database program should already have the ability to perform products. The ® symbol indicates that ''Multiplication'' is a registered trademark somewhere, which is unlikely, as the term is not unique. However, common words are registered as parts of longer trademarks rather often.

* '''ζ (lowercase zeta): This math will only lead to more math.''' — Frequently used for the {{w|Riemann zeta function}} in analytic number theory, a function of complex numbers which is challenging even to define and which is the focus of a famously unsolved problem in highly advanced mathematics. Zeta is used much less often in other contexts, such as the ζ-potential in colloidal chemistry, and even there it is likely to just lead to more math. It is also used for another sequence of transfinite numbers, which will also lead to more math.

* '''β (lowercase beta): There are just too many coefficients.''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by subscript, or compacted into matrix notation) would be used, while there is only ever a single zeroth-order coefficient α in these models. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.

* '''α (lowercase alpha): Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.''' — As the first Greek letter, α is used for a tremendous variety of purposes in math. For example, it is used to represent the probability of a Type-I error (false positive) occurring in a hypothesis test. It could also possibly refer to the {{w|fine-structure constant}} which shows up in high energy physics, atomic physics, quantum electrodynamics, and at least [[1047|one other xkcd comic]]. Alpha could also refer to {{w|angular acceleration}}, and a rapidly-rotating system is capable of killing people in a number of [[123|interesting ways]]. Another dangerous meaning for α comes from ionising α-radiation: while it can be easily blocked by even a sheet of paper, it has been {{W|Alexander Litvinenko#Poisoning and death|used for assassinations}} through ingestion.

* '''Ω (capital omega): Oooh, ''some'' mathematician thinks their function is cool and important.''' — The last letter of the Greek alphabet and thus often seen as momentous (the end, the final word, death). The capital letter has been used as the symbol for a {{w|Omega_function|variety of mathematical functions}}, the {{w|first uncountable ordinal}}, and {{w|Absolute Infinity}}. It is commonly used in physics and electrical engineering as the symbol for {{w|ohms}}, a unit for electrical resistance. Capital omega has produced a fascination in common culture, perhaps due to God reportedly describing himself as "the alpha and the omega" in the Book of Revelation or due to its highly distinctive shape. It is often used to represent something of grave or transcendent significance. So using it to name your function (instead of a conventional symbol like ''f'' or ''g'') may mean you think the function is particularly important.

* '''ω (lowercase omega): A lot of work went into these equations and you are going to die here among them.''' — Used for the {{w|Transfinite_number|least transfinite ordinal number}}, the order type of the natural numbers under '<'. The line about dying here among the transfinite equations may be in reference to the "eternity" of the infinite set it represents. It is also used in physics and electrical engineering for angular frequency, equal to 2π times the frequency, and thus it is ubiquitous in equations dealing with all sorts of wave phenomena. '''ω''' is also used for the angular velocity of a rotating system, defined by '''v''' = '''r'''×'''ω'''.

* '''σ (lowercase sigma): Some poor soul is trying to apply this math to real life and it's not working.''' — In statistics, σ commonly refers to the population standard deviation of a distribution. Many simplified statistical equations substitute the population standard deviation σ for the sample standard deviation s for simplicity, even when this is not justifiable. A common example is using the normal distribution to model the mean of several identically-normally-distributed variables instead of the T distribution. The variant ς is used at the end of Greek words (called the "final sigma") but is rarely used in math or science.

* '''ξ (lowercase xi): Either this is terrifying mathematics or there was a hair on the scanned page.''' — Randall comments that this looks like a strand of curly hair. Xi is used in the {{w|Riemann Xi function}} and sometimes as a variable or function symbol in higher math. It is famously difficult to write in a way that is consistent and clearly distinct from other symbols.

* '''γ (lowercase gamma): ''Zoom'' pew pew pew [space noises] ''zoooom!''''' — Lowercase gamma is used for the {{w|Lorentz factor}}, an important variable in special relativity calculations. Its use implies that you are dealing with speeds approaching the speed of light and therefore with spaceships or other moving objects not confined to Earth. γ-rays are also the highest energy photons, so a space opera might have ships flying near the speed of light firing gamma-ray weapons that go PEW PEW. γ is also used as the symbol for the Euler-Mascheroni constant and occasionally as a variable or function name.

* '''ρ (lowercase rho): Unfortunately, the test vehicle suffered an unexpected wing separation event.''' — Used in statistics to measure association between variables. Lowercase rho often represents volumetric mass density, such as the density of air that a wing might be travelling through. The density of a fluid is directly proportional to the Reynold's number which dictates the sort of physics used to model motion through the fluid. Flying a plane in conditions with a Reynold's number well outside of what it was designed for could have catastrophic consequences. A variant symbol ϱ with the same meaning is common in European handwriting.

* '''Ξ (capital xi): Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.''' — Probably the least used Greek letter in math and physics despite being easy to write and to recognize. According to the comic, anyone using this letter is likely a being from another planet. It does see very occasional use, such as in the Riemann xi function or as the symbol for a class of heavy baryons in particle physics. It resembles, but is not to be confused with a "hamburger button" or a triple equals sign ≡. Coincidentally, it also resembles the simplified Hanzi (Chinese) character for the [https://en.wikibooks.org/wiki/Chinese_(Mandarin)/Numbers number 3]. Randall thinks it most closely resembles alien writing.

* '''ψ (lowercase psi): You have entered the domain of King Triton, ruler of the waves.''' — Both capital and lowercase psi are shaped like tridents. In classical mythology, {{w|Triton}} is one of the gods of the sea, alongside his father Poseidon, and tridents are commonly associated with sea gods. In quantum mechanics, either psi is used to represent the wave function of a particle, leading to a pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, and the supergolden ratio, and other purposes.)

==Transcript==
:[A list with 21 explanations of different Greek letters. To the left the letter (on in one case two letters) are shown, and then the explanation is written to the right in one or two lines (and in one case on three lines). Above these explanations there is a header in a slightly larger font:]
:<big>What Greek letters mean in equations</big>
:π This math is either very simple or impossible.
:Δ Something has changed.
:δ Something has changed and it's a mathematician's fault.
:θ Circles!
:Φ '''''O R B S'''''
:ϵ Not important, don't worry about it.
:υ,ν Is that a v or a u? Or...oh no, it's one of ''those''.
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.
:Σ Thank you for purchasing ''Addition Pro''®!
:Π ...and the ''Multiplication''® expansion pack!
:ζ This math will only lead to more math.
:β There are just too many coefficients.
:α Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.
:ω A lot of work went into these equations and you are going to die here among them.
:σ Some poor soul is trying to apply this math to real life and it's not working.
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.
:ψ You have entered the domain of King Triton, ruler of the waves.

{{comic discussion}}

[[Category:Math]]
[[Category:Aliens]]

User talk:Yosei

2022-03-21T20:21:23Z

Yosei: Created page with "I'm not exactly a very active editor here, but am open to any comments etc if any. Sorry in advance if I'm slow to reply back in case someone commented something here. ~~~~"

I'm not exactly a very active editor here, but am open to any comments etc if any. Sorry in advance if I'm slow to reply back in case someone commented something here. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 20:21, 21 March 2022 (UTC)

User:Yosei

2022-03-21T20:15:17Z

Yosei: Created page with "Hi there!"

Hi there!

2586: Greek Letters

2022-03-21T20:12:27Z

Yosei: /* Greek letters */ additional info about ϖ etc

{{comic
| number = 2586
| date = February 25, 2022
| title = Greek Letters
| image = greek_letters.png
| titletext = If you ever see someone using a capital xi in an equation, just observe them quietly to learn as much as you can before they return to their home planet.
}}

==Explanation==
{{incomplete|Created by '''''O R B S''''' PRO®- Missing explanations for some letters. The text for each letter should be in the explanation with an attempt at explaining it. This has not been included and many of the letters have no explanation of the given text, only for what they actually are used for. Do NOT delete this tag too soon.}}
Mathematics uses lots of Greek letters, typically using {{w|Greek_letters_used_in_mathematics,_science,_and_engineering|the same letter consistently}} to represent a particular constant or type of variable. This comic gives a (non-)explanation of what they typically mean, see [[#Greek letters|below]].

In the title text the joke about capital Xi from the main comic is continued. In the main comic those using Ξ (capital xi) greets us as Earth mathematicians, indicating they are not from Earth, but have come here to learn what we know of math. In the title text the idea that any one using Ξ must be aliens is made clear. So if you ever meet someone using this letter while doing math, then learn as much as you can by quietly observing them, before they return to their home planet. Either learn from their possible advanced math (that allowed them to construct a way to get from one star system to another), or learn about them as the aliens species they represent.

Previously [[Randall]] made a similar comic, [[2520: Symbols]], about math symbols.

===Greek letters===

* '''π (lowercase pi): This math is either very simple or impossible.''' — Typically used to refer to the constant ratio between a circle’s circumference and its diameter (approximately 3.14). In a common school curriculum, this constant first shows up in introductory geometry classes, which would be considered "simple" by advanced mathematicians. But often, pi can show up seemingly randomly in advanced equations that have nothing to do with a circle at first glance, such as in infinite series. And because pi is transcendental, it can sometimes be difficult to work with pi in those situations. The comic may also be a reference to the impossibility of squaring the circle.
* An alternate explanation is that the comic refers to how the symbol can sometimes be used as a variable where the 'p' sound might make sense, such as in the prime-counting function where it stands for "prime" or the Buckingham π theorem where it stands for "parameter." These uses can be confusing to students who have only ever seen a lowercase pi used for the circle constant. This has pushed college courses to use it less and less frequently for anything other than the circle constant, so that now you are only likely to see π as something else in higher math. (More confusing still is the variant lowercase pi, so-clled omega pi {{w|Pi_(letter)#Variant_pi|ϖ}} sometimes used for angular frequency instead of the more common (and very similar-looking) lowercase omega ω. In Astronomy, ϖ is traditionally used to denote the {{w|Longitude of the periapsis|longitude of perihelion}}.)

* '''Δ (capital delta): Something has changed.''' — Typically prefixes a variable to refer to a macroscopic change in or finite difference of that variable. For instance, Δ'''v''' may be the finite change in velocity '''v''' over some finite time span, while Δ[''f''](''x'') represents the forward difference of ''f'' at ''x'', defined as Δ[''f''](''x'') = ''f''(''x''+1) - ''f''(''x'').

* '''δ (lowercase delta): Something has changed and it's a mathematician's fault.''' — Used in calculus. In many areas of maths we study systems by introducing small changes (perturbations) in input variables and observing how the system changes. The perturbations introduced are often written down as ''x'' → ''x'' + ''δx'' for some variable ''x'' we're perturbing, where ''δx'' is the change we've introduced. These are often applied in physics (perturbation theory, principle of least action, Noether's theorem,…). Since this change was purposefully introduced by the mathematician instead of occurring naturally, it is therefore their fault.

* '''θ (lowercase theta): Circles!''' — Used in trigonometry. Typically used to refer to an angle, and is notably used in the polar coordinate system. The text refers to its close relationship with circles, on which the polar coordinate system is based. In European handwriting, the variant form ϑ is commonly used with the same meaning.

* '''φ (lowercase phi): ''ORBS''''' — Typically used to refer to another angle other than one referred to by theta. It's used in spherical coordinates, and the text refers to how spheres, or orbs, are important in spherical coordinates. Lowercase phi has two forms in modern typography which are confused by this website's default font. In the comic, it has a complete circle with a vertical line passing through it, which is what Knuth called "phi." The alternate form, ϕ, is what Knuth called "variant phi" and can be written in a single stroke. Most fonts reverse the way these symbols are rendered. There is no difference in meaning between the symbols. Additionally, "O R B S" is written with spaces between each letter, possibly a reference to the linguistic phenomena of surreal memes and their tendency to add spaces between letters of "surreal-sounding" words like "orbs".

* '''ϵ (lowercase epsilon): Not important, don't worry about it.''' — Typically used to refer to a very small quantity. ϵ may be an error term in a statistical model (which is usually small if the model is useful), a remainder term in an approximation (same), or an arbitrarily small (positive) quantity in analysis. Although a total cumulative change of "ϵ" is negligible, in analysis, ϵ is most often applied in a context of an infinitesimal change occurring with infinite frequency. The study of ratios of quantities that approach zero gives rise to infinitesimal calculus. Also used for a sequence of transfinite numbers that are unreachable from ω by finite application of addition, multiplication, and exponentiation. This Greek lowercase letter has two common modern variants, ϵ and ε. ϵ is called the "{{w|Epsilon#Unicode|lunate epsilon}}" and may be more common in the U.S. A stylized version (∈) is used as the mathematical symbol for "is an element of." ε is what Knuth called the "variant epsilon" and is never used for the "element of" symbol but otherwise has identical meaning. Because epsilon represents an arbitrarily small (positive) quantity, there's no reason for anyone to worry about it from a practical standpoint. Also used in set theory to show a number is part of a set, e.g. X ϵ Y (x is part of set Y).

* '''υ,ν (lowercase upsilon and nu): Is that a v or a u? Or...oh no, it's one of ''those''.''' — Common in college level physics and engineering equations. ν commonly represents wavenumber in physics as well as a wide variety of other variables, often with names starting in N (e.g. neutron) or V (e.g. viscosity). Lowercase upsilon is rarely used, probably to avoid confusion. The symbols look remarkably similar to Latin u and v, to the point that they are nearly indistinguishable in some fonts; Randall has complained about this before in [[2351: Standard Model Changes]].

* '''μ (lowercase mu): This math is cool but it's not about anything that you will ever see or touch, so whatever.''' — Used broadly in the abstract mathematical fields of category theory and measure theory. Also used in statistics for mean (average). Physicists use Latin letters for the indices of the 3-vectors of classical physics and Greek indices, including μ, for the 4-vectors of special relativity. This leads to μ being ubiquitous in a field which is very far from everyday experience (where speeds approach the speed of light). It is also employed in statistics for the population mean, which is a quantity that the statistician never actually knows and frequently wants to estimate. Equations requiring a μ are thus impossible to apply directly. However, μ is used in physics for the coefficient of friction in the Coulomb model, typically used to approximate resistive forces between dry solids of different material sliding past each other. A very common use of μ in science and engineering is as the symbol of the SI prefix ''micro-'' for a millionth. Unicode has officially added a point for μ as the "micro sign," distinct from its usual codepoint as the lowercase Greek letter mu.

* '''Σ (capital sigma): Thank you for purchasing ''Addition Pro''®!''' — Typically used as a symbol for the sum of a series of numbers. The comic is making fun of summation, pointing out that it's essentially a complicated, "pro" version of simple addition. The capital sigma is often used as the icon for the all-important "sum" button in spreadsheet software. However, the sigma operator is often necessary for explicitly defining infinite sums, avoiding ambiguous notation like an ellipsis (...).

* '''Π (capital pi): ...and the ''Multiplication''® expansion pack!''' — Typically used as a symbol for the product of a sequence of numbers. The joke is the same as for summation. Here, it is advertised as an "expansion pack," a term used for a piece of software that cannot stand alone but adds features to some existing software. Any paid spreadsheet or database program should already have the ability to perform products. The ® symbol indicates that ''Multiplication'' is a registered trademark somewhere, which is unlikely, as the term is not unique. However, common words are registered as parts of longer trademarks rather often.

* '''ζ (lowercase zeta): This math will only lead to more math.''' — Frequently used for the {{w|Riemann zeta function}} in analytic number theory, a function of complex numbers which is challenging even to define and which is the focus of a famously unsolved problem in highly advanced mathematics. Zeta is used much less often in other contexts, such as the ζ-potential in colloidal chemistry, and even there it is likely to just lead to more math. It is also used for another sequence of transfinite numbers, which will also lead to more math.

* '''β (lowercase beta): There are just too many coefficients.''' — This could be a reference to the typical usage of beta to represent coefficients of independent variables in the {{w|Ordinary_least_squares#Linear_model|ordinary least squares regression model}}. Regression can potentially have a large number of independent variables, hence potentially many different betas (differentiated by subscript, or compacted into matrix notation) would be used, while there is only ever a single zeroth-order coefficient α in these models. Alternatively, the comic might suggest whatever source this equation is from has run out of Latin letters to use as symbols, and is now going through the Greek letters.

* '''α (lowercase alpha): Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.''' — As the first Greek letter, α is used for a tremendous variety of purposes in math. For example, it is used to represent the probability of a Type-I error (false positive) occurring in a hypothesis test. It could also possibly refer to the {{w|fine-structure constant}} which shows up in high energy physics, atomic physics, quantum electrodynamics, and at least [[1047|one other xkcd comic]]. Alpha could also refer to {{w|angular acceleration}}, and a rapidly-rotating system is capable of killing people in a number of [[123|interesting ways]]. Another dangerous meaning for α comes from ionising α-radiation: while it can be easily blocked by even a sheet of paper, it has been {{W|Alexander Litvinenko#Poisoning and death|used for assassinations}} through ingestion.

* '''Ω (capital omega): Oooh, ''some'' mathematician thinks their function is cool and important.''' — The last letter of the Greek alphabet and thus often seen as momentous (the end, the final word, death). The capital letter has been used as the symbol for a {{w|Omega_function|variety of mathematical functions}}, the {{w|first uncountable ordinal}}, and {{w|Absolute Infinity}}. It is commonly used in physics and electrical engineering as the symbol for {{w|ohms}}, a unit for electrical resistance. Capital omega has produced a fascination in common culture, perhaps due to God reportedly describing himself as "the alpha and the omega" in the Book of Revelation or due to its highly distinctive shape. It is often used to represent something of grave or transcendent significance. So using it to name your function (instead of a conventional symbol like ''f'' or ''g'') may mean you think the function is particularly important.

* '''ω (lowercase omega): A lot of work went into these equations and you are going to die here among them.''' — Used for the {{w|Transfinite_number|least transfinite ordinal number}}, the order type of the natural numbers under '<'. The line about dying here among the transfinite equations may be in reference to the "eternity" of the infinite set it represents. It is also used in physics and electrical engineering for angular frequency, equal to 2π times the frequency, and thus it is ubiquitous in equations dealing with all sorts of wave phenomena. '''ω''' is also used for the angular velocity of a rotating system, defined by '''v''' = '''r'''×'''ω'''.

* '''σ (lowercase sigma): Some poor soul is trying to apply this math to real life and it's not working.''' — In statistics, σ commonly refers to the population standard deviation of a distribution. Many simplified statistical equations substitute the population standard deviation σ for the sample standard deviation s for simplicity, even when this is not justifiable. A common example is using the normal distribution to model the mean of several identically-normally-distributed variables instead of the T distribution. The variant ς is used at the end of Greek words (called the "final sigma") but is rarely used in math or science.

* '''ξ (lowercase xi): Either this is terrifying mathematics or there was a hair on the scanned page.''' — Randall comments that this looks like a strand of curly hair. Xi is used in the {{w|Riemann Xi function}} and sometimes as a variable or function symbol in higher math. It is famously difficult to write in a way that is consistent and clearly distinct from other symbols.

* '''γ (lowercase gamma): ''Zoom'' pew pew pew [space noises] ''zoooom!''''' — Lowercase gamma is used for the {{w|Lorentz factor}}, an important variable in special relativity calculations. Its use implies that you are dealing with speeds approaching the speed of light and therefore with spaceships or other moving objects not confined to Earth. γ-rays are also the highest energy photons, so a space opera might have ships flying near the speed of light firing gamma-ray weapons that go PEW PEW. γ is also used as the symbol for the Euler-Mascheroni constant and occasionally as a variable or function name.

* '''ρ (lowercase rho): Unfortunately, the test vehicle suffered an unexpected wing separation event.''' — Used in statistics to measure association between variables. Lowercase rho often represents volumetric mass density, such as the density of air that a wing might be travelling through. The density of a fluid is directly proportional to the Reynold's number which dictates the sort of physics used to model motion through the fluid. Flying a plane in conditions with a Reynold's number well outside of what it was designed for could have catastrophic consequences. A variant symbol ϱ with the same meaning is common in European handwriting.

* '''Ξ (capital xi): Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.''' — Probably the least used Greek letter in math and physics despite being easy to write and to recognize. According to the comic, anyone using this letter is likely a being from another planet. It does see very occasional use, such as in the Riemann xi function or as the symbol for a class of heavy baryons in particle physics. It resembles, but is not to be confused with a "hamburger button" or a triple equals sign ≡. Coincidentally, it also resembles the simplified Hanzi (Chinese) character for the [https://en.wikibooks.org/wiki/Chinese_(Mandarin)/Numbers number 3]. Randall thinks it most closely resembles alien writing.

* '''ψ (lowercase psi): You have entered the domain of King Triton, ruler of the waves.''' — Both capital and lowercase psi are shaped like tridents. In classical mythology, {{w|Triton}} is one of the gods of the sea, alongside his father Poseidon, and tridents are commonly associated with sea gods. In quantum mechanics, either psi is used to represent the wave function of a particle, leading to a pun. (Psi is also used in mathematics to represent the sum of the inverse of the Fibonacci numbers, the division polynomials, and the supergolden ratio, and other purposes.)

==Transcript==
:[A list with 21 explanations of different Greek letters. To the left the letter (on in one case two letters) are shown, and then the explanation is written to the right in one or two lines (and in one case on three lines). Above these explanations there is a header in a slightly larger font:]
:<big>What Greek letters mean in equations</big>
:π This math is either very simple or impossible.
:Δ Something has changed.
:δ Something has changed and it's a mathematician's fault.
:θ Circles!
:Φ '''''O R B S'''''
:ϵ Not important, don't worry about it.
:υ,ν Is that a v or a u? Or...oh no, it's one of ''those''.
:μ This math is cool but it's not about anything that you will ever see or touch, so whatever.
:Σ Thank you for purchasing ''Addition Pro''®!
:Π ...and the ''Multiplication''® expansion pack!
:ζ This math will only lead to more math.
:β There are just too many coefficients.
:α Oh boy, now ''this'' is math about something real. This is math that could ''kill'' someone.
:Ω Oooh, ''some'' mathematician thinks their function is cool and important.
:ω A lot of work went into these equations and you are going to die here among them.
:σ Some poor soul is trying to apply this math to real life and it's not working.
:ξ Either this is terrifying mathematics or there was a hair on the scanned page.
:γ ''Zoom'' pew pew pew [space noises] ''zoooom!''
:ρ Unfortunately, the test vehicle suffered an unexpected wing separation event.
:Ξ Greetings! We hope to learn a great deal by exchanging knowledge with your Earth mathematicians.
:ψ You have entered the domain of King Triton, ruler of the waves.

{{comic discussion}}

[[Category:Math]]
[[Category:Aliens]]

2214: Chemistry Nobel

2022-03-20T04:32:44Z

Yosei: /* Explanation */ "row ," -> "row,"

{{comic
| number = 2214
| date = October 11, 2019
| title = Chemistry Nobel
| image = chemistry nobel.png
| titletext = Most chemists thought the lanthanides and actinides could be inserted in the sixth and seventh rows, but no, they're just floating down at the bottom with lots more undiscovered elements all around them.
}}

==Explanation==
The {{w|Periodic table|periodic table of the elements}} is a display which arranges all of the 118 ({{w|Oganesson|currently}}) known chemical elements by atomic number and sorts them into columns such that each column contains a group of elements displaying similar chemical properties. The original version of this table was developed by Russian chemist {{w|Dmitri Mendeleev}} in 1869, when he realized that certain properties repeated periodically as elements became more massive. Notably, this system left obvious gaps at the top of the table. Mendeleev correctly predicted that some of these gaps represented elements that had not been discovered yet, and even predicted their properties based on the patterns in the table. The later discovery of those elements (including germanium and gallium) helped validate Mendeleev's work. Other gaps, however, were not due to undiscovered elements, but merely resulted from the properties of electron {{w|orbitals}} in atoms: upper rows of the table represent orbitals with fewer possible electrons and hence fewer elements, so displaying the lower rows properly below the upper ones leaves gaps in the upper rows. In other words, elements could not actually exist in these spaces, spaces which only existed in the realm of human bookkeeping. The joke of this comic is that it treats these gaps as if they represented elements that hadn't been discovered yet. Ponytail and her team have won the Nobel Prize in Chemistry merely by looking for and finding these elements. She expresses surprise that no one else had thought of such a simple direction for research.

By definition, each element has one more proton than the previous element - so element 1, hydrogen, has one proton in the nucleus, while element 2, helium, has two protons in the nucleus. The periodic table represents elements in their atomic form, where there are an equal number of protons and electrons (as opposed to an ionized form where they are unequal), so the structure of the periodic table is based on the structure of the "orbitals" that electrons fall into.

The first row of the periodic table has elements whose electrons only have an "s orbital" (at least when the electrons are in their ground state, which is the non-excited state that they are normally in). There is only one s orbital in each row, and an s orbital only has room for two electrons, so there are only two elements in the first row. The Pauli exclusion principle, mentioned in xkcd 658, means that only two electrons can be in each orbital. The second row of the periodic table contains elements with only s and p orbitals. As mentioned, there is only one s orbital at each "level" of orbital, with each level basically corresponding to a row, but there are three p orbitals at each level, so there can be four total pairs of elements in the second row, for eight total elements in the second row. (You can see that level one has a total of 1^2 orbitals, or 1 orbital, while level two has 2^2 orbitals, or 4 orbitals.) After p orbitals, the next type of orbital that can exist at higher levels is a d orbital. For levels that have a d orbital, there are five d orbitals at each level. Beginning with the fourth row, you can see elements whose highest-energy electrons are in an s orbital (the first two columns), a p orbital (the last six columns), or a d orbital (the middle ten columns). The d orbitals for row four are actually classified as the 3d orbitals (meaning they belong to level three), but because they have higher energy than the 4s orbital, they are put on the fourth row. The "aufbau principle" says that electrons fill the lowest energy orbitals first, which means that level one orbitals get filled before level two orbitals, which get filled before level three orbitals, and that within each level the s orbitals get filled before the p orbitals. So, there are two columns on the periodic table for each orbital - although helium is put in the far right instead of in the second row with the other elements whose highest electron is the second one in an s orbital, because putting it on the far right shows that helium is stable like the other "noble gases" in the far right row.

The final type of orbital that exists as the ground state for a known element is the f orbital, but almost all periodic tables show the elements with their highest electrons in an f orbital - the lanthanides and actinides that are mentioned in the title text and described below - in rows below the table, to prevent the table from becoming too wide to print easily.

The comic is based on the joke that somehow every physicist and chemist for generations somehow missed that there are actually p and d orbitals at levels one and two, and so it shows the empty space in the columns corresponding to the p and d orbitals in level one and the d orbitals in level two being filled with undiscovered elements. In reality, there are no p or d orbitals at the first level and no d orbital at the second level, due to quantum mechanics (involving the possible values of something called the quantum n, l, m, and s numbers, where n is the level and l determines whether is an s, p, d, or f orbital). The comic also shows a line of d orbital elements in the third row, even though the 3d orbitals are already represented in the fourth row (where they are placed due to having higher energy than the level 4 s orbitals). The Pauli exclusion principle has been known since 1925, and Mendeleev (mentioned in xckd 965) developed the structure of the periodic table in 1863 to describe the structure of the known elements, so the idea that such a basic thing as more elements in the early rows that had never been discovered by any chemist ever would be quite surprising. In reality, the elements toward the top of the periodic table that are known to be naturally occurring were generally discovered earlier, while all the most recently discovered elements are higher-numbered elements lower down on the table that are very short-lived before they undergo radioactive decay to another element and have never been seen to be naturally occurring.

The lanthanides and actinides mentioned in the title text are series of elements with higher atomic numbers that have electrons in orbitals that no previous elements have, and thus occupy columns of the periodic table that don't exist for lower-numbered elements. Sometimes these elements are [https://commons.wikimedia.org/wiki/File:32-column_periodic_table-a.png displayed in the table], a format that corresponds with their actual orbital structure; this format is too wide for most display media, thus the lanthanides and actinides are separated out and displayed "floating" beneath the rest of the periodic table. The title text jokes that these floating series of elements are actually surrounded by actual elements.

In real life, the 2019 Nobel Prize in Chemistry was awarded to [https://www.nobelprize.org/prizes/chemistry/2019/press-release/ John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino] for their work in the development of lithium-ion batteries; it was announced on October 9, just a few days before this comic was published, so the chemistry Nobel Prize was in the news.

==Transcript==
:[Ponytail stands in front of an image with a white section in the shape of the 7 rows of the periodic table of the elements, but without the two rows usually shown beneath with the lanthanides and actinides. The “empty” sections at the top of the table are filled with three rows of dotted boxes, 16 boxes in the top row and two rows with 10 boxes each, shifted one right from the top row. Ponytail points to this area with a pointer while she looks and gestures towards an off-panel audience.]
:Ponytail: I don't know why no one else thought to look here.

:[Caption below the panel]:
:The 2019 Nobel Prize in Chemistry went to the team that discovered the elements in the big gap at the top of the periodic table.

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Chemistry]]
[[Category:Nobel Prize]]

2581: Health Stats

2022-03-20T04:28:07Z

Yosei: /* Explanation */ more harmful that -> more harmful than

{{comic
| number = 2581
| date = February 14, 2022
| title = Health Stats
| image = health_stats.png
| titletext = You will live on forever in our hearts, pushing a little extra blood toward our left hands now and then to give them a squeeze.
}}

==Explanation==
[[Cueball|Cueball's]] has a smartwatch that tells him a new health statistic. It is clearly either a new watch or a newly discovered feature added to his existing one.

It seems to monitor the volume of blood currently in his left hand (specifically the one the watch is being worn on the wrist of, implying it tracks the inflow and outflow and maintains a running tally) and conveys this quantity in milliliters (ml). It also tracks other stats like his pulse, as seen later, but this is not what currently interests Cueball. Instead he studies the blood volume information and finds it changing from moment to moment. This may be from a combination of his pulse (misaligned to the frequency of the updates) or the vertical position and attitude of his hand (he subtly changes the hand's position from panel to panel). It could just be inaccuracies in the data, an issue with all scientific instruments but more so for consumer devices used without practiced expertise - it is unlikely he has strapped the measuring device tight enough onto his wrist to give scientifically consistent results, even with such slight arm movements as he makes.

He reports his thoughts on this to someone off-panel, who is heard replying to all his comments. At first, Cueball just voices the assumption that the small change is normal, and accepts the movement away from a number he had no reason to disbelieve as realistic. But then two measurements in a row both increase. Although all the changes are slight, compared to the magnitude of the numbers themselves, this freaks him out. He may be [[605: Extrapolating|extrapolating these two data points]] into the future - if this rather selective trend continues, his hand may explode from its ever-increasing volume of blood. Either this, or Cueball noticed that the variation in the first three data points was ±0.025, but the final variation suddenly surpasses this level by ten times this range, massively redefining his evolving expectations.

For whatever reason he becomes anxious, a consequence of this is that his pulse also begins to rise, as also documented by the watch. This could simultaneously increase his blood pressure (not noted as being another monitored statistic) and in turn causing another rise in the volume of blood in his hand. Knowledge of the pulse increase makes him even more alarmed, which will cause a positive feedback loop at least in the short term.

The total difference between the maximum (22.09 ml) and minimum volume (21.81 ml) of blood in his hand is only 0.28 ml compared to an average of 21.9 ml, so less than 1.5% difference. This can realistically be assumed to be a normal fluctuation from heartbeat to heartbeat and/or with change of posture. For that matter, neither Cueball nor ourselves may have any idea what a normal volume of blood in his left hand would be. His comment in the first panel is that he's "not sure how to interpret" the initial measurement, and it might need rather uncommon medical knowledge to do so - even those who have learnt how much blood a typical human body should contain might be stumped by how much of that is just within a typical (or specific) human hand. However, he seems to have assumed that 21.83 ml was a normal measurement simply since it was the first one he saw (a stereotypical {{w|Confirmation_bias#Preference_for_early_information|preference for early information}}).

Just before his anxiety reaches breaking point, his off-panel friend begins to tell him to stop looking at the watch all the time, but is interrupted mid-sentence by Cueball actually freaking out. This final outbreak causes his off-screen companion to tease him by saying that "We will treasure your memory", thus joking that Cueball will soon die from the blood loss when his hand explodes.

The title text continues with this teasing where the friend jokes that after his demise he will live on forever in his friends' hearts. From there he will thus also be responsible for pushing a bit more blood into his friends' left hands, now and again, so they can feel this as a squeeze to remind them of how they lost their friend to a left-handed blood explosion.

This is likely meant to parody the tendency of people to monitor minute details of their own health, pandered to by possibly misguided developments in personal meditech, without having a clear idea of what any of the data means. This is arguably much more common today with health devices readily available, which can give the average person data about their own body but often don't offer useful context. Cueball is apparently sufficiently fixated on data that apparent changes to any metric causes him to panic. He doesn't know what the blood volume of his hand means for his health, or even whether it's a useful metric, yet he obsesses over perceived trends in the data. The irony is that his very focus causes a more important metric (his pulse rate) to elevate. This may be intended to suggest that excessive fixation on one's own health can cause elevated anxiety. Ironically, this stress can potentially be more harmful than the things that the person has become upset about.

==Transcript==
:[Cueball is looking down and to the right at his bent arm, where a small device is radiating as shown with several small lines. Above him the message from the device is shown in a frame, that is divided in two by a line. The top part has one line of text, with a x at the end for closing the message. And below in the second half are two lines of text. Cueball is speaking to someone off-panel, who replies from a starburst at the panel's edge.]
:Box title bar: New health stat!
:Box: Left hand blood volume: 21.83 mL
:Cueball: Oh. Cool. Not sure how to interpret that, but good to know, I guess.
:Off-panel voice: I guess!

:[Same setting but Cueball has turned to the left, still looking at his device on his bend arm. The message on the device is now only showing the message part, so it is no longer divided into two parts.]
:Box: Left hand blood volume: 21.81 mL
:Cueball: Huh, it's going down. I guess that happens.
:Off-panel voice: Mhm.

:[In a frame-less panel, Cueball now has both arms bent with his hands close together in front of him. He has once again turned toward the right, and is still looking at the device.]
:Box: Left hand blood volume: 21.86 mL
:Cueball: Oh weird, now it's going up higher than before.
:Off-panel voice: Maybe you shouldn't look at-

:[Cueball now holds his arm with the device outstretched towards the right, with his other arm bent in front of him a finger raised.]
:Box: Left hand blood volume: 22.09 mL
:Cueball: It's going '''''way''''' up! '''''Is my hand exploding?!'''''
:Cueball: And now my pulse is rising! '''''Aaaaa!!!!'''''
:Off-panel voice: So sorry. We will treasure your memory.

{{comic discussion}}

[[Category:Comics with lowercase text]]
[[Category:Comics featuring Cueball]]
[[Category:Biology]]

Talk:2595: Advanced Techniques

2022-03-20T04:19:32Z

Yosei:

The title text refers to [[wikipedia:Noether's theorem|Noether's theorem]]. [[User:Trimeta|Trimeta]] ([[User talk:Trimeta|talk]]) 04:24, 19 March 2022 (UTC)

This is my first explanation [[User:GcGYSF(asterisk)P(vertical line)e|GcGYSF(asterisk)P(vertical line)e]] ([[User talk:GcGYSF(asterisk)P(vertical line)e|talk]]) 05:41, 19 March 2022 (UTC)

This sounds a lot like Laplace or Fourier transforms, converting a function into a different where it is easier to manipulate then reversing the transformation. [[Special:Contributions/108.162.245.173|108.162.245.173]] 06:28, 19 March 2022 (UTC)
:When I was learning to use fourier transforms in EE, they were very straightforwardly (and accurately) described as "transferring the function to the Spectral Domain". [[Special:Contributions/172.70.110.241|172.70.110.241]] 22:45, 19 March 2022 (UTC)

I'm not sure that it's proper to refer to someone as a "giant" while explaining a comic that references mythological creatures. Unless it was literal of course, but as far as I'm aware giants never existed. [[Special:Contributions/162.158.111.12|162.158.111.12]] 11:28, 19 March 2022 (UTC)
:I think she may actually have been a wizard-giant.[[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 13:41, 19 March 2022 (UTC)

Not my area, but I am passingly familiar with the [[:wikipedia:Gauss–Kuzmin–Wirsing_operator|Gauss–Kuzmin–Wirsing Operator]], [[wikipedia:Dragon curve|Dragon Curves]], and [[wikipedia:Hilbert spaces|Hilbert ''Spaces'']] (guessing that the "arrow" refers to scalar vector?). Some type of iterative/recursive conversion that yields to analysis of the period? Probably not pertinent to the joke which is more about the fanciful names attached to mathematical concepts, constructs, and processes [[Special:Contributions/108.162.245.173|108.162.245.173]] 11:53, 19 March 2022 (UTC)

I find it inteteresting that despite now being the day after release (or well into the next day, my time, which is usually sufficient — and I'm not in a DST zone yet) the site explanation hasn't explained (or thought it has explained) every single element of the in-comic 'explanation' — even if not established the (probably) nonsensical whole. As an example, I don't yet see the obvious {{w|Dragon_curve|dragon}} element that is both alluded to ''and'' seemingly illustrated upon the board-notes. Leaving this here to help near-future editors who might have time to bullet-point/tabulate/sub-heading these things and just need that extra bit of info. [[Special:Contributions/162.158.159.125|162.158.159.125]] 15:01, 19 March 2022 (UTC)

There is the misquote of Arthur Clarke "All sufficiently advanced [strike]technologies[/strike] mathematical techniques are indistinguishable from magic." [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]])
:Fix it!
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

The explanation should decide whether the teacher is Miss Lenhart, or Blondie. I think it's Miss Lenhart. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 17:02, 19 March 2022 (UTC)

That dragon looks suspiciously like Trogdor...[[Special:Contributions/162.158.146.73|162.158.146.73]]

"Critical Role: Call of the Netherdeep" released this week, for D&D 5e.
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

Come to think of it, we do use fantasy-sounding expressions in math: e.g. titanic prime, imaginary part, infinite field, ideals, friendly numbers, brute force attack. I'm pretty sure there are many more fun examples.

PS: "Sexy primes" and "latus rectum" are real technical terms.
[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 04:16, 20 March 2022 (UTC)

Talk:2595: Advanced Techniques

2022-03-20T04:16:39Z

Yosei:

The title text refers to [[wikipedia:Noether's theorem|Noether's theorem]]. [[User:Trimeta|Trimeta]] ([[User talk:Trimeta|talk]]) 04:24, 19 March 2022 (UTC)

This is my first explanation [[User:GcGYSF(asterisk)P(vertical line)e|GcGYSF(asterisk)P(vertical line)e]] ([[User talk:GcGYSF(asterisk)P(vertical line)e|talk]]) 05:41, 19 March 2022 (UTC)

This sounds a lot like Laplace or Fourier transforms, converting a function into a different where it is easier to manipulate then reversing the transformation. [[Special:Contributions/108.162.245.173|108.162.245.173]] 06:28, 19 March 2022 (UTC)
:When I was learning to use fourier transforms in EE, they were very straightforwardly (and accurately) described as "transferring the function to the Spectral Domain". [[Special:Contributions/172.70.110.241|172.70.110.241]] 22:45, 19 March 2022 (UTC)

I'm not sure that it's proper to refer to someone as a "giant" while explaining a comic that references mythological creatures. Unless it was literal of course, but as far as I'm aware giants never existed. [[Special:Contributions/162.158.111.12|162.158.111.12]] 11:28, 19 March 2022 (UTC)
:I think she may actually have been a wizard-giant.[[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 13:41, 19 March 2022 (UTC)

Not my area, but I am passingly familiar with the [[:wikipedia:Gauss–Kuzmin–Wirsing_operator|Gauss–Kuzmin–Wirsing Operator]], [[wikipedia:Dragon curve|Dragon Curves]], and [[wikipedia:Hilbert spaces|Hilbert ''Spaces'']] (guessing that the "arrow" refers to scalar vector?). Some type of iterative/recursive conversion that yields to analysis of the period? Probably not pertinent to the joke which is more about the fanciful names attached to mathematical concepts, constructs, and processes [[Special:Contributions/108.162.245.173|108.162.245.173]] 11:53, 19 March 2022 (UTC)

I find it inteteresting that despite now being the day after release (or well into the next day, my time, which is usually sufficient — and I'm not in a DST zone yet) the site explanation hasn't explained (or thought it has explained) every single element of the in-comic 'explanation' — even if not established the (probably) nonsensical whole. As an example, I don't yet see the obvious {{w|Dragon_curve|dragon}} element that is both alluded to ''and'' seemingly illustrated upon the board-notes. Leaving this here to help near-future editors who might have time to bullet-point/tabulate/sub-heading these things and just need that extra bit of info. [[Special:Contributions/162.158.159.125|162.158.159.125]] 15:01, 19 March 2022 (UTC)

There is the misquote of Arthur Clarke "All sufficiently advanced [strike]technologies[/strike] mathematical techniques are indistinguishable from magic." [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]])
:Fix it!
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

The explanation should decide whether the teacher is Miss Lenhart, or Blondie. I think it's Miss Lenhart. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 17:02, 19 March 2022 (UTC)

That dragon looks suspiciously like Trogdor...[[Special:Contributions/162.158.146.73|162.158.146.73]]

"Critical Role: Call of the Netherdeep" released this week, for D&D 5e.
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

Come to think of it, we do use fantasy-sounding expressions in math: e.g. titanic prime, imaginary part, infinite field, ideals, friendly numbers, brute force attack. I'm pretty sure there are many more fun examples.
[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 04:16, 20 March 2022 (UTC)

2520: Symbols

2021-10-04T20:20:22Z

Yosei: /* Explanation */ Kelvin is not "proportional" to Celsius

{{comic
| number = 2520
| date = September 24, 2021
| title = Symbols
| image = symbols.png
| titletext = "röntgen" and "rem" are 20th-century physics terms that mean "no trespassing."
}}

==Explanation==
{{incomplete|Created by VERY EXPENSIVE EQUIPMENT - Please change this comment when editing this page. Do NOT delete this tag too soon. Bare-bones explanation is in, but needs much more detail.}}

This comic refers to elements of (mostly mathematical or engineering) notation commonly used in various fields of math and science. Each piece of notation is presented as "symbolizing" not what it specifically means, but a typical ''context'' in which it might be encountered. Many of the individual descriptions look like verbiage that might be found on informational or warnings signs or placards, although typically with a silly edge.

*d⁄dx: An undergrad is working very hard
d/dx is the symbol for a single-variable {{w|Derivative|derivative}}. This is one of the basic operations in {{w|calculus}} and consequently is ubiquitous in the work of undergraduates in the sciences. A hard-working undergraduate in the relevant fields would churn through exercises using this symbol.

*∂⁄∂x: A grad student is working very hard
The replacement of the standard "d" letters with the curly letters "∂" denotes the partial derivative, which generalizes the ordinary derivative to multi-variable calculus. Problems with partial derivatives, especially partial differential equations, can be extremely challenging. Although PDEs would typically be first taught at an undergraduate level, difficult partial derivatives would be encountered in graduate-level work.

*ħ: Oh wow, this is apparently a quantum thing
ħ (pronounced "h-bar") is a symbol used for (the reduced) {{w|Planck's constant}}, a universal, fundamental constant in quantum physics. ħ is equal to the energy of a photon divided by its frequency, and angular momentum in quantum mechanical systems is measured in quantized integer or half-integer units of ħ.
Classical physics appears as a limit of quantum physics if all "actions" (quantities of dimension energy * time, momentum * length, or angular momentum) are much larger than ħ. Conversely you can also formally set ħ=0 to get classical results from quantum formulae. This means that effects which are proportional to some power of ħ cannot be explained classically, and instead are "a quantum thing".

*Rₑ: Someone needs to do a lot of tedious numerical work; hopefully it's not you
The {{w|Reynolds number}} (which is actually usually denoted by "Re," not "Re" as it appears in the comic) is the most important dimensionless group in fluid mechanics. Named for Osborne Reynolds, Re characterizes the relative sizes of inertial and viscous effects in a moving fluid. Large values of Re are indicative of turbulent flow, which cannot usually be solved for analytically, and so numerical modelling is necessary. Accurate numerical studies of high-Reynolds-number flows are notoriously difficult to create and program.

Alternatively, Rₑ could stand for electronic {{w|transition dipole moment}} in a molecule. This appears in quantum-mechanical calculations of transition probabilities and also includes a lot of unpleasant numerical work. Rₑ is also a term used for the radius of the Earth at mean sea level, though this is not necessarily a complex term in and of itself.

Another alternative is that Rₑ could refer to Relative Error, a measurement of precision or accuracy. Used often in the analysis of scientific data and in numerical analysis.

*(Ta⁴ - Tb⁴): You are at risk of skin burns
The {{w|Stefan-Boltzmann law}} says that a perfectly absorbing ("black body") source emits electromagnetic radiation with a power per unit area of σT4, where σ is a known constant and T is the absolute temperature. The quantity (Ta4 – Tb4) thus appears in any calculation of purely radiative energy transfer between two bodies, one at temperature Ta and the other at Tb. When radiative transfer is large enough to be the most important form of heat interchange, it is normally also large enough to sear the skin with thermal or ultraviolet burns.

*NA: You are probably about to make an incredibly dangerous arithmetic error
NA, or {{w|Avogadro's number}}, is the number of molecules in a mole of a substance—roughly the number of protons plus neutrons in 1 gram of matter. This is an enormous number, exactly 6.022 140 76 × 10²³, or 602 214 076 000 000 000 000 000. Adding up molecular weights and converting between grams and moles of several substances is a lot of arithmetic on a scale where intuition won't help you catch mistakes. Working with NA, it is easy to make errors of one or more powers of ten without noticing. If this kind of error is made in the calculation of the stoichiometrically correct amount of a reagent in a chemical reaction, it is possible to accidentally create dangerous amounts of unwanted chemical products.

*µm: Careful, that equipment is expensive
{{w|Micrometre|Micrometer}}s are a very small unit of distance. Micrometers are commonly used to measure wavelengths in the infrared, and infrared detectors are very expensive, compared with visible wavelength counterparts. Of course, micrometers are used as a measurement of distance in other contexts, but any distance-measuring device capable of accurately measuring micrometer distances would also be expensive. Similarly, tools used to create or calibrate items within micrometer tolerances can also be expensive.

*mK: Careful, that equipment is very expensive
{{w|Kelvin}} is a temperature scale roughly speaking similar to Celsius, but taking absolute zero as its zero point instead of the freezing point of water (rigorously speaking, its definition is now {{w|2019_redefinition_of_the_SI_base_units#Kelvin|based on the Boltzmann constant}}). {{w|Millikelvin}}s (1/1000 of a Kelvin) are used for high precision temperature work. Frequently this is used in processes of cooling temperatures to near absolute zero - such as superconductors or other quantum effects that occur when atoms are almost still. This is suggesting that the symbol appears on a sensitive experimental system probing quantum mechanical behavior that would likely only exist in an advanced laboratory. Any equipment that works down at mK temperatures, or at least to mK precision and accuracy, is likely to be very expensive.

*nm: Don't shine that in your eye
{{w|Nanometer}}s are frequently seen in the listed wavelengths for lasers. Pointing a visible or infrared laser at someone's eye is notoriously dangerous; the tightly-focused coherent light can cause permanent damage very quickly.

*eV: Definitely don't shine that in your eye
{{w|Electron volt}} energies are typical of moderate-energy particle beams, produced by accelerating electrons (or protons) over macroscopic voltages. These particle beams can be {{w|Anatoli Bugorski|even more damaging}} to soft tissues than optical-wavelength lasers.

*mSv: You are about to get into an Internet argument
The {{w|millisievert}} is a unit of radiation dose absorbed. It is actually a very small dosage, but the joke refers to Internet trolls debating the effects of low-dose radiation sources, such as 5G wireless networks. [[Randall|Randall's]] comment may also be referring to [https://xkcd.com/radiation/ this chart].

*mg/kg: Go wash your hands
This unit measures the dose of a drug or other chemical in milligrams per kilogram of body mass. If the appropriate dose - or worse, the lethal dose - is measured in mg/kg (parts per million), then the substance may be quite toxic.

*µg/kg: Go get in the chemical shower
A unit 1/1000 times the size of mg/kg. If a dosage is measured in micrograms per kilogram (parts per billion), any accident probably requires whole-body decontamination procedures.

*π or τ: Whatever answer you get will be wrong by a factor of exactly two
π is defined as the ratio of a circle's circumference to its diameter, while τ is defined as the ratio of a circle's circumference to its radius (and is therefore equal to 2π). {{w|pi|π}} has been used as the primary constant for describing the circumference and area of circles for millennia, but proponents of {{w|Turn (angle)|τ}} claim that τ is actually more natural in most contexts, since it makes working in radians more straightforward. The joke here is that whichever constant you use, it will probably be the wrong one (off by a factor of two, one way or the other) for the formula you are trying to use. The debate over Tau vs Pi was solved by Randall in this compromise: [[1292: Pi vs. Tau]].

The title text refers to two non-SI units of radiation measurement, {{w|Roentgen (unit)|röntgen}} and {{w|Roentgen equivalent man|rem}}. In the mid-20th century when they were in use, the dangers of radiation weren't as well understood as today, so an area with radiation that was noteworthy back then is probably dangerous ( https://www.bloomberg.com/news/articles/2019-08-28/france-is-still-cleaning-up-marie-curie-s-nuclear-waste ), hence the no trespassing part.

==Transcript==
:[A list with 14 different scientific constants/symbols are shown. Next to each symbol is a description. Above the list is a heading and beneath that a subheading.]
:::::<big>Symbols</big>
::::And what they mean

:::d⁄dx    An undergrad is working very hard
:::∂⁄∂x    A grad student is working very hard
:::ħ       Oh wow, this is apparently a quantum thing
:::Rₑ     Someone needs to do a lot of tedious numerical work; hopefully it's not you
:(Ta⁴ - Tb⁴)    You are at risk of skin burns
:::NA    You are probably about to make an incredibly dangerous arithmetic error
:::µm    Careful, that equipment is expensive
:::mK    Careful, that equipment is very expensive
:::nm    Don't shine that in your eye
:::eV     '''''Definitely''''' don't shine that in your eye
:::mSv  You are about to get into an internet argument
::mg/kg      Go wash your hands
::µg/kg      Go get in the chemical shower
::π or τ      Whatever answer you get will be wrong by a factor of exactly two

{{comic discussion}}

[[Category:Math]]
[[Category:Physics]]
[[Category:Chemistry]]
[[Category:Biology]]
[[Category:5G]]

Talk:2493: Dual USB-C

2021-08-27T01:12:25Z

Yosei:

Is "USB-AC" in the title text a reference to the fact that this looks like an AC power plug, or is that a legitimate variant of USB-C? [[Special:Contributions/172.68.55.65|172.68.55.65]] 18:09, 27 July 2021 (UTC)
:I think it refers to the polarized version of the 1-15 plug, where one blade is bigger than the other. A USB version of that could have one blade as a USB-A and the other a USB-C. This then also invites the AC pun that you mention. ----PF

I guess this is how connector vendors maintain backwards compatibility for USB-C. ----DaveK

I would have thought it was cursed more from what would happen if you plugged it into a standard ac outlet. [[Special:Contributions/162.158.74.107|162.158.74.107]] 04:49, 24 July 2021 (UTC)
:Does USB C actually fit inside an outlet? (As I live in europe, I really have no clue...) [[Special:Contributions/141.101.105.7|141.101.105.7]] 07:42, 26 July 2021 (UTC)
:: i'm pretty sure it doesn't (should be wasy to test for any american who owns a USB-C plug), and the third point in the list mentions that currently, which actually renders the first two points immaterial. [[Special:Contributions/162.158.88.188|162.158.88.188]] 14:41, 26 July 2021 (UTC)
:::This does not fit into a standard AC outlet. However, I have seen plenty of outlets, especially on extension cords, which might allow one of the USB-C plugs to touch the live contact.[[User:Geek Prophet|Geek Prophet]] ([[User talk:Geek Prophet|talk]]) 18:16, 26 July 2021 (UTC)

Looks good. But I'll obviously need a BS 1363/Type-G converter! [[Special:Contributions/141.101.99.211|141.101.99.211]] 09:14, 24 July 2021 (UTC)

It's worth noting, Dell already does this with the WD19DCS... [[Special:Contributions/141.101.99.211|141.101.99.211]] 09:23, 24 July 2021 (UTC) Gargravarr

Is it worth pointing out that "cursed X" is a meme, c.f. /r/cursedimages? I think this is the first time xkcd has referenced it. --[[User:Esogalt|Esogalt]] ([[User talk:Esogalt|talk]]) 14:59, 24 July 2021 (UTC)
:No I do not think so. That something is cursed is not special to a meme. This reminds more of the bad map projections series. Wonder if more will follow. Have added this similarity in title to the explanation. Starting with a very high number just like that series. In that series number 4 comic just came out, so interesting to see if he has planned more of these. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:32, 25 July 2021 (UTC)

This comic yet has no categories. And I cannot think of any suitable? Something with electronics that is not a category yet? I mean it can be used with smart phones and computers, but is not only used for one of these? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:32, 25 July 2021 (UTC)
:I was thinking something like 'Spurious Series(es?)'. It could encompass My Hobby and Map Projections as child-categories (they're self-categorised, I'm fairly sure without checking) but any lone "Something-Or-Other #xyz" like this is added as a direct example. And then if "Something-Or-Other #pqr" ever happens and is so categorised it ''highlights'' the need to create a Something-Or-Other category and reassign membership to this instead. If it never gets any direct companions, it can stand out as a spurious to the extent of never being partnered by up to ''xyz-1'' other later examples.
:Non-spurious serieses (xkcdphone, e.g.) that start with example #1 (or even un-numbered, but clearly item 1 in hindsight) might be better to be dealt with as is. But anything pretending to be just one of dozens/hundreds of as-yet-untold examples, especially out of index order (#1 is unlikely to be referenced, for reasons of refusing to establish a truly comprehensive catalogue that doesn't even exist, but would not necessarily disqualify such a leap-frogging/randomly-sampled series if it appeared anyway, after the original asynchro ous+gappy impressions) is probably an intentional Spurious Series.
:Or find an even better term. Or supercategorise Series with subcats of Storytelling/Chronicalling/Chronological (Journal), Upgrades/Revisiting (xkcdphone, also Internet Map?) and Spurious/Ad Hoc (as above), allowing room for future additions to revisit the true nature of the series concerned.
:Would need a proper editorial policy discussion, of course, especially to find better terminology (of whatever form of grouping(s) the final conclusion recommended). But perhaps you can see some glimmer of (a different?) solution in what I have just suggested. Putting it out there so at least it's there to be ignored or dismissed as overthinking the matter. [[Special:Contributions/141.101.99.183|141.101.99.183]] 16:43, 25 July 2021 (UTC)
:>This comic yet has no categories. And I cannot think of any suitable? Something with electronics that is not a category yet?
:Maybe we can create a (joke) category, "Category: Pages Not Belonging to Any Categories" :) Also, "List of pages that does not include itself as a list item"... Russell’s paradox is rather xkcd-ish. — [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 01:12, 27 August 2021 (UTC)

I seem to recall at least one other xkcd strip that was "Cursed". I think it was cursed office chairs. That would make at least two comics in the "Cursed" category. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 14:45, 26 July 2021 (UTC)
:There is also the cursed store that beret guy gets all his stuff from, only to find out later that the item is cursed but when he goes back to the store it's gone. Maybe this is one of the items he recently purchased and couldn't return? [[Special:Contributions/127.0.0.1|127.0.0.1]] 21:51, 25 July 2021 (UTC)

:Not sure if you mean [[2332: Cursed Chair]] or [[2144: Adjusting a Chair]].
:--[[User:FrankHightower|FrankHightower]] ([[User talk:FrankHightower|talk]]) 19:05, 28 July 2021 (UTC)

The need of dual plugs could also be a result of the increasing power consumption of some devices, as suggested with the Macbook-compatible high-performance dongles in the explanation. USB-C is limited to 100 W, what is not bad for this tiny pins - [https://en.wikipedia.org/wiki/USB-C#Power_issues_with_cables Wiki USB-C power issues]. So crude soft- and hardware design, e.g of high performance laptops, leads to dual plugs or an additional power plug next to the dock connector. [[Special:Contributions/162.158.134.94|162.158.134.94]] 11:47, 27 July 2021 (UTC)

"Cursed Connectors #187" - Section 187 of the California Penal Code covers murder. [[User:ProfDigory|ProfDigory]] ([[User talk:ProfDigory|talk]]) 23:53, 28 July 2021 (UTC)

Talk:2498: Forest Walk

2021-08-20T08:13:40Z

Yosei: help you down in 1860: Communicating

Have just added a transcript. Hope I did good! :) -Lance ([[Special:Contributions/172.70.126.211|172.70.126.211]] 02:40, 5 August 2021 (UTC))
:You did good, Lance. *pats head* [[Special:Contributions/162.158.74.197|162.158.74.197]] 18:06, 5 August 2021 (UTC)

Wonder what Beret Guy would do if Cooper said, "I don't have it any more," since some of the money was discovered, badly deteriorated and partially buried, along the banks of the Columbia River back in 1980, as verified by serial numbers on the found currency. Given the absence of any other evidence, it was assumed that the hijacker had gotten separated from the money either during or right after the jump, the found currency had been deposited as flotsam at its discovery point through the actions of the river itself, and the rest of the money was still somewhere in the Pacific Northwest awaiting similar discovery, [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 04:23, 5 August 2021 (UTC)

If it can be considered that the comic is a reference to random walk (in a forest), can it also be considered a reference to [https://en.wikipedia.org/wiki/Random_forest random forests] ? [[Special:Contributions/141.101.68.73|141.101.68.73]] 07:14, 5 August 2021 (UTC)
:I don't get why the comic is supposed to be a reference to random walks or to random forests. Nothing points to that. Real forests exists, and people walk in them. The only peculiarity of this particular forest is that D.B. Cooper hangs in one of its trees. --[[Special:Contributions/188.114.103.244|188.114.103.244]] 08:20, 5 August 2021 (UTC)

I feel like there should be a D.B. Cooper category at this point. --[[Special:Contributions/141.101.104.52|141.101.104.52]] 07:51, 5 August 2021 (UTC)

Hey there, I think the alt text is also a reference to https://xkcd.com/2390/ ? Kind regards :) [[Special:Contributions/162.158.89.61|162.158.89.61]] 08:13, 5 August 2021 (UTC)

Typo: "he might have simply inherited it form his mom". --[[Special:Contributions/162.158.255.39|162.158.255.39]] 12:40, 5 August 2021 (UTC)
: Done, now. I'd seen it, but apparently missed it, in preparing for my first big corrective edit of the day (little tyops, a lot less awful than ones ''I'' have previously left for others to correct). Or maybe I thought I should leave it suspended from the tree until some other issue had been resolved. :P [[Special:Contributions/162.158.158.105|162.158.158.105]] 12:53, 5 August 2021 (UTC)

Not to question the artistic representation, but rather than Forest (tree canopy and dense undergrowth), I'd say that was more Woodland Savanna (individual tree growth smattered around grass/shrubland at most). Or maybe we just can't properly see the woods for the trees... (Or the action is set at the edge of a clearing, of course!) [[Special:Contributions/141.101.98.184|141.101.98.184]] 13:32, 5 August 2021 (UTC)
:It's Southwest Washington, where Pyroculture practiced over centuries changed the nature of the forests. Your average forest, until recently when fire suppression came in, had very little undergrowth, and sometimes whole fields of Camas Lilly or Tarweed or other food plants valued by the Yakima.[[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 19:43, 5 August 2021 (UTC)
::Savanna (savannah? - I always thought it had that spelling, but too lazy to check my convictions) is pretty much the product of pyroculture, though not of course the only one. Intensity and accompanying herbiculture/arboriculture being practiced could make some differences, and climate too (NW US is famously damp most of the time, so may be hard to overburn in primitive anthropogenic fire-settings). But even without a modern parafoil-type chute there's likely an attempt to aim for landing in a clearing (with a basic back-bleeding canopy and shifting weight/tugging the harnessed bundles of lines asymetrically used to activelychange heading) only to over-/under-shoot the landing slightlty and apparently snag upon a tree. That might indicate a localalised area of ground more close to the relative sparseness of the illustration. [[Special:Contributions/162.158.111.122|162.158.111.122]] 03:49, 10 August 2021 (UTC)

Doesn't it seem likely, that Beret Guy's trees have soup outlets on them? Like his Business does? (Or, maybe Ghosts (like the business))

'You help me down this instant!' is not an "unlikely combination of words" or an unusual phrase. I'm not sure if it is regional, but as a native US English speaker, this is a completely normal wording to use if you are frustrated and insisting that someone do something, especially someone much younger, so perhaps it is meant to further indicate the man's age. As an example, a parent might say to their unruly child who is refusing to do their chores, "young man, you clean your room this instant!" (or "right this instant") It can also be used playfully: you are taking a walk along a river with some friends, when one of them suddenly playfully splashes water on you and takes off running (to avoid retaliation) and you run after them shouting "I'm going to get you for that! You get back here right this instant!" [[Special:Contributions/172.70.131.28|172.70.131.28]] 15:36, 5 August 2021 (UTC)
:I had the same reaction to both the title text and the explanation (although I believe it refers to the "help me down" part and not the "this instant" part). Either way, neither part of the phrase nor the entire phrase seems unlikely or unusual. I actually first came to this page to see if I was missing a reference in the title text, but it appears Randall just finds our dialectic somewhat strange. [[Special:Contributions/172.70.114.73|172.70.114.73]] 16:28, 5 August 2021 (UTC)
::IANALinguist, but I took it that "Help me down" is a (potentially, enough to be linguistically nerdsniped upon) ambiguous. 'Down' as a verb is strange, maybe ("to down, I wish you to help me") which might even be more feather-based in regards to the action conveyed. Or "lower the amount of help you shall grant me". Or even "(I) require assistance (for) I (am) feeling a certain amount of ennui". And "I wish to fall" is obviously not meant... Or is it? Some people would wish to consider this... [[Special:Contributions/162.158.158.211|162.158.158.211]] 19:06, 5 August 2021 (UTC)
:::It was I who added that part about the "unlikely combination of words". Today I have checked it on https://www.english-corpora.org/coca/ (where you have to annoyingly register with your real email address as throwaway mails are effectively blocked). Expression 'right know' has 151 795 results. 'this instant' has only 558 including phrases such as:
:::"Get the fuck out of my office this instant." from Silicon Valley (2017 TV Series, episode The Keenan Vortex);
:::"Shh. Stop that this instant! 'Stop that this instant.' You sound like my teacher." Justice League Action (2016, Galaxy Jest);
:::"Put those drapes down this instant. ... I will grab a spatula and put you Over my knee this instant! - You sound like mommy." The Haunted Hathaways (2014, Haunted Viking);
:::"Applebloom! You come back here right this instant! (blustering)" My Little Pony: Friendship Is Magic (2010, Bridle Gossip).
:::There were also some result from spoken word, newspapers and blogs but they were not relevant. In conclusion, 'this instant' is much less frequent than more common 'right know', however, it is used. On the other hand, it is infrequent enough that characters in TV series comment on how out of place that phrase sounds. I have deleted my explanation, feel free to undo the deletion, rewrite the explanation or leave it as it is now.
::: To clarify, I have deleted this part of explanation: As mentioned in [[1400: D.B. Cooper]], Cooper was also known for ambiguous, possibly affected speaking style and use of unusual phrases such as 'negotiable American currency', he seems to hold to this habit and instead of much more common 'Help me right now!' or 'Put me down immediately!' he used rather unlikely combination of words 'You help me down this instant!'. [[User:CryptoNut1269|CryptoNut1269]] ([[User talk:CryptoNut1269|talk]]) 11:06, 6 August 2021 (UTC)
::::I assume you mean "right now" not "right know". [[Special:Contributions/172.70.126.165|172.70.126.165]] 01:05, 7 August 2021 (UTC)Pat
::: My input: the "this instant" bit is not even mentioned as the focus of the linguist's attention, so I'd not consider that important. D.B. may also have only started to say that ''since'' the prior visitor, or only when directly addressing BG (with the long history of ignoring/refusing him). "Help me down" is an interesting construct in and of itself, as mentioned. But I could not tell you in what ways. [[Special:Contributions/162.158.158.106|162.158.158.106]] 14:39, 6 August 2021 (UTC)
:Just FYI: I accidentally noticed that [[1860: Communicating]] has this caption: [...] “which explains why you haven't been able to convince anyone to '''help you down''' from that wall.” — [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 08:13, 20 August 2021 (UTC)

Anyone else think that D.B. Cooper in this comic looks a bit like Don Quixote from alternate energy revolution? --[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 02:13, 6 August 2021 (UTC)
: Kind of, but when you looked closer at [[556: Alternative Energy Revolution]] Don Quixote's beard is definitely better groomed and his hair is trimmed. I would rather compare this Cooper with the guy form [[725: Literally]]. [[User:CryptoNut1269|CryptoNut1269]] ([[User talk:CryptoNut1269|talk]]) 11:06, 6 August 2021 (UTC)
:: <humor> What if literally guy is alternate universe D.B. Cooper? </humor> Seriously speaking though, it seems the similarity is just because there aren't many different ways to draw stick figures. --[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 19:41, 6 August 2021 (UTC)

Where's the page for yesterday's 2499:Abandonment Function? I know it was published late (after midnight last night), but is that a reason not to explain it? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 12:54, 7 August 2021 (UTC)
:Sometimes DGBRTBot (however it's capitalised, etc, I forget) needs a nudge. It's a long long time since I last saw that need so seriously doing, so can't remember how difficult it was when everyone was last complaining about it... I'm sure others are checking that, but I'll poke around to see if it's possible to poke as an AnonIP too... [[Special:Contributions/141.101.99.12|141.101.99.12]] 17:55, 7 August 2021 (UTC)
:: I think my desire to archive the comic along with everything else in case the universe ends is simplifying down to just pasting a link in here: https://xkcd.com/2499/ . Presently accessible for me on xkcd.com . Has a single panel showing a drone asking to be charged by an owner it gifts itself to. Somewhat triggering around human slavery. Caption describes an abandonment function that provides for unwanted drones to find new owners. Reminds of discarded autonomous robots. archive.org will be crawling it soon, hopefully before the universe ends, but I wrote a small summary here. [[Special:Contributions/172.70.114.87|172.70.114.87]] 20:04, 7 August 2021 (UTC)
:: commentary: this probably actually works to give drones away, comparable to leaving furniture by the side of the street. [[Special:Contributions/108.162.219.11|108.162.219.11]] 20:06, 7 August 2021 (UTC)
::: The way to get rid of things by the side of the street is not to have a "free to a good home" sign, but to make it actually tempting to just take it. Many a broken fridge has been given a price-tag and "see owner" label and ended up (even less responsibly) taken away by someone who thinks that even if that price is a steal, they'll happily do their own stealing. (Anyway, the article now exists, after a fashion.) [[Special:Contributions/141.101.98.157|141.101.98.157]] 23:07, 7 August 2021 (UTC)

If D. B. Cooper is hanging from his parachute from a tree branch, why are the parachute lines slack? [[Special:Contributions/172.69.68.184|172.69.68.184]] 19:30, 9 August 2021 (UTC)
:''Some'' are slack, but a core set (below the bit of the chute-canopy snagged most firmly in the tree-canopy) are taut. Which might be expected, as airflow isn't fairly equally holding all the deployed fabric up, just the bits hooked most upon the highest branches that remain unbroken/unbent after entanglement. The rest of the fabric drapes itself on lower branches and the non-loadbearing chords form basic (or modified by chord/branch interaction) cateneries between the silk and the backpack anchor-point.
:Though it could as easily end up being one edge of the 'chute (as seen from a chosen angle) as a saddle-like distribution with a centre (maybe just front or back?) held up and two limbs (of the presumably hemispherical, not aerofoil, style of construction surely typical of the day).
:It is of course a fairly trivial sketch of an entangled chute, not a complexly rendered simulation of an idealised draping and suspension-from. But I think I'd have mistrusted an all-taut set of guylines compared with that fairly feasible depiction. YMMV. [[Special:Contributions/162.158.111.122|162.158.111.122]] 03:49, 10 August 2021 (UTC)

Talk:2492: Commonly Mispronounced Equations

2021-08-17T23:22:17Z

Yosei: real life examples

This comic is obviously a take on the generation Z style of writing words without vowels so that they fit on T-Shirts, text messages or to avoid censorship, like "BRLN", "O RLY", "PIX PLZ". Some of the people from that generation are now established scientist, leading their respective fields forward. Obviously this is how they refer to common equations. [[Special:Contributions/162.158.92.29|162.158.92.29]] 13:10, 22 July 2021 (UTC)

I think the wave equation is wrong based on units, but it's been a while. The wave speed ought to be squared. Of course, ''c'' could be a squared speed, but it's usually not. [[Special:Contributions/172.70.34.164|172.70.34.164]] 01:22, 22 July 2021 (UTC)

:I agree, normally it's written as C squared... The equations in order are 1: Gravitational Attraction, 2: Einstein's Mass / Energy Conversion, 3: Pythagorean Theorem (triangle side relations), 4: Area of a Circle, 5: Entropy equation, 6: Ideal Gas Law, 7: Euler's Identity, 8: Newtons Second law, 9: Wave equation, 10: The derivative of a function f, and, 11: The Quadratic Equation... I don't understand the linguistic rules being applied to the names, but they seem to be visual as much as anything [[Special:Contributions/108.162.237.66|108.162.237.66]] 02:04, 22 July 2021 (UTC)
::You should turn that into a table in the explanation. We can have a column where we try to come up with the pronunciation rule. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:10, 22 July 2021 (UTC)

The equation for the thing I have as what it was made by is 𝓛 = i(ѱ-macron)γᵘ(∂ᵤ)ѱ-e(ѱ-macron)γᵘ(Aᵤ + Bᵤ)ѱ - m(ѱ-macron)ѱ - (FᵤᵥFᵘᵛ)/4 {{w|Quantum electrodynamics#Equations_of_motion|here is the link:}} [https://en.m.wikipedia.org/wiki/Quantum_electrodynamics#Equations_of_motion These are both the links.]
For archival, this is the thing: LAGRONJ EYSIBARYMOODMOOSIOYLERSIBRYMOOAMOOBAMOOSIMASIBRSIQORTFAHMOOVYFAHMOOVY.
[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 02:22, 22 July 2021 (UTC)

My friends and I actually pretty often say "PəV-nert" for the ideal gas law. First syllable is kind of vowel-less, sort of a schwa if anything. But also stressed? Didn't know you could stress a schwa but, guess I did.
[[Special:Contributions/172.70.130.160|172.70.130.160]] 02:36, 22 July 2021 (UTC)
:My teachers always pronounced it PIV-nert. [[Special:Contributions/172.69.62.20|172.69.62.20]] 18:38, 22 July 2021 (UTC)

I think this is the XKCD that has made me laugh the most, out of all 2492.
:I'd say it might be the one that made me laugh the most, out of all {{LATESTCOMIC}}. I won't, because it didn't, but I could. --[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 03:23, 22 July 2021 (UTC)
:"Doot-ca-doox" is so funny. I'm imagining Pingu saying that. !!!!

I tried to transcribe these pronunciations into IPA, because reading them like this is kind of ambiguous. I probably got a bunch of stuff wrong though.
fəˈdʒæmɚ |
ˈɛmkɑˌtu |
ætˈbutkut |
ˈæpɚˌtu |
həˈsplɒgpi |
ˈpævnɚt |
ˈaɪpɪn |
ˈfimɑ |
dut kəˈduks |
ˈfækslɪmˌoʊ ˈfæksəˌfɒx |
zəˈbɔbə fækˈtoʊɑ |
ˌɛpsɪˈhutəˌmu ˈdupsɪˌkwɔrps

Why is it a soft G in the gravity equation? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:10, 22 July 2021 (UTC)
:I believe it's a reference to the "gif" pronunciation debate. "Fuh-gam-er" is the obvious pronunciation, Randal is facetiously asserting "Fuh-jam-er" is correct.--[[Special:Contributions/108.162.250.130|108.162.250.130]] 05:00, 22 July 2021 (UTC)
:I think it might be because the English letter "G" is pronounced "Gee" (i.e. "Jee"), which made its way into the pronunciation here.[[User:BenjaminTheBenevolent|BenjaminTheBenevolent]] ([[User talk:BenjaminTheBenevolent|talk]]) 10:27, 22 July 2021 (UTC)
:[https://www.youtube.com/watch?v=_Ok_GMxThuo How would you pronounce the word 'give'?] !!!!
:(The English ''letter'' pronunciation is "Jee". It's also pronounced as an "F" in "Enough" and "" in "Gnome", etc.) [[Special:Contributions/162.158.158.197|162.158.158.197]] 19:37, 28 July 2021 (UTC)
The most similar time when equations are actually 'pronounced' a bit like this is the "soh cah toa" mnemonic for the trigonometric identities - should this be in the explanation? (the comic made at least me think that might be the original inspiration) [[Special:Contributions/141.101.99.204|141.101.99.204]] 06:42, 22 July 2021 (UTC)

:How is "soh cah toa" a mnemonic?? It's just a bunch of random letters. Normally you memorize random letters by coming up with words that fit together, not vice versa. I think this is much harder to remember than the thing it is supposedly a mnemonic for. If anyone actually finds it useful, can you explain how it works for you? I've seen this before so I suppose it's a real thing, but I find it baffling. [[Special:Contributions/108.162.221.220|108.162.221.220]] 04:15, 23 July 2021 (UTC)
::You ask how it's a mnemonic, yet you say you've seen it before. Think about that for a sec.
[[User:Klo876|Klo876]] ([[User talk:Klo876|talk]]) 01:58, 24 July 2021 (UTC)
::Not sure it's a mnemonic, no, but I was taught SOHCAHTOA by a very good (but strict) maths teacher as in "... (like?) that volcanic eruption". Given we were 10, 11 years old, I don't think we even ''knew'' about {{w|Krakatoa}} at that point (despite having also a very good Geography teacher who readily identified lumps of 'Gneissian schist' that I may have brought back from holiday - he also had a much better sense of humour...) so whether I (or the teacher?) was mistaken in understanding "Sohcahtoa" to be purported to be a (now ironically memorable) volcano rather than it was a "it rhymes with..." mnemonic, I don't now know. But since then I have always used SOHCAHTOA to confirm in my mind which trigonometric identity I should use. And, later, I learnt and never forgot that {{w|Krakatoa,_East_of_Java|Krakatoa is/was ''west'' of Java}}! [[Special:Contributions/141.101.98.230|141.101.98.230]] 08:20, 23 July 2021 (UTC)
::(PS - If I ever have to use the "Many Very Elderly Men Just..." mnemonic (or whatever it is, I was sure it had had Earthenware Vases, but maybe only in a reversed version!), I tend to have to ''backform'' it from my unclear recollection of the mnemonic(s) I've been told plus just ''knowing'' that it's "Mercury, Venus, Earth, Mars, **, Jupiter, Saturn, Uranus, Neptune*, Pluto-if-we're-counting-it*" (* - except between 1979 and 1999 when it was "...Pluto-definity-counted-at-this-time, Neptune") (** - and then there's possibly an A, B or C here for Asteroid, Belt or Ceres; nobody I know has ever added Kuiper and/or Oort into the string of words to need remembering, though) using very non-mnemonical direct or indirect knowledge about the solar-system, like Clarke's written version of 2001 aiming at Saturn but Kubrik's film 'only' going as far as Jupiter. So I "(Sometimes?) Might Very Earnestly Make And Join Something Unprecedented Never Known Originally" on the spur of the moment.)
:: The point of soh-cah-toa is that you learn to say it aloud as one word (which is therefore memorable), and then can expand it out as an acronym for sin(x) = o/h, cos(x) = a/h, tan(x) = o/a, which wouldn't be memorable. Much like BIDMAS/PEDMAS is pronounced as one word to learn an acronym. [[Special:Contributions/162.158.158.176|162.158.158.176]] 18:32, 26 July 2021 (UTC)
:The circle area might be meant to read out like "upper two", referencing the square. I can't see the same for any of the others though. / [[Special:Contributions/162.158.183.157|162.158.183.157]] 06:52, 22 July 2021 (UTC)

:Mneumonics are supposed to make it easier to remember the equations; this collection would actually make it more challenging to remember these. Mind you, as a math tutor, my first thought was that these were attempts at mnemonics that missed the mark, '''badly'''. [[User:Nutster|Nutster]] ([[User talk:Nutster|talk]]) 15:04, 22 July 2021 (UTC)

I see nobody has attempted the Transcript yet. (Also I'm wondering how to 'properly' pronounce P-One V-One Over T-One Equals P-Two V-Two Over T-Two.) [[Special:Contributions/162.158.155.157|162.158.155.157]] 10:41, 22 July 2021 (UTC)
:I started a transcript. --[[User:4D4850|4D4850]] ([[User talk:4D4850|talk]]) 16:54, 22 July 2021 (UTC)

Sorry to come in as an amateur, but I think the equation pronounced Ha-SPLOG-pee is actually the equation for Shannon diversity. [[Special:Contributions/162.158.126.134|162.158.126.134]] 11:58, 22 July 2021 (UTC)
: In my opinion, most of the contributions here are from people pretending to know more than they do. Edit away. Be bold. [[Special:Contributions/172.70.114.172|172.70.114.172]] 21:04, 22 July 2021 (UTC)

The Pythagorean Theorem one made me think of the AT-AT debate for Star Wars
:The wave equation reminded me of Jimmy Durante's Ink A Dinka Doo: https://www.youtube.com/watch?v=EWqi9eWwXvk I think I'm dating myself (no one else will). [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 16:55, 22 July 2021 (UTC)

I don't think it's clear if the provided pronunciations are the ''Correct'' ones or the common ''mispronunciations''

It's worth noting that the majority of these equations are especially likely to be elided, and that the way they're routinely elided is generally incorrect - and more than that, the stressed syllable in particular is likely wrong. Especially notably "Fu-Jam-Er" should be "Fu-Gam-Er" and "Pav-Nert" should be "Piv-Nert". The joke works on the level of equation pronunciation being pretty intrinsically funny if you're not familiar with the specific equation, but also on the level of the specific equations having a standard pronunciation that pointedly isn't the one in the comic.

It would be interesting to try and reverse-engineer the original equations behind, for example, "Fus ro dah", or "Avada Kedavra". [[User:Cavaler|Cavaler]] ([[User talk:Cavaler|talk]]) 12:53, 23 July 2021 (UTC)

What is the pronounciation notation this comic is using?? I can't even find them in Oxford/Cambridge/Merriam-Webster/Collins dictionary, though I think I occasionally see them somewhere else. --[[User:Lamty101|Lamty101]] ([[User talk:Lamty101|talk]]) 08:43, 24 July 2021 (UTC)
: It's probably not actually right to consider it a notation, ''per se''. It's a trivial method that anyone can use (no need to use funny stuff like ɛ, ʑ or ɖʐ in IPA notation - or remember what they mean!), but it's also liable to inconsistency as you can be inconsistent in both production (some might consider "DOO" ''or'' "DU" an acceptible rendering for the same thing) or understanding (if "BAI" is written used, was that as in "good''bye''" (see also "BIE") or "e''Bay''" (also could have been "BAE"), etc?). How would you indicate syllable boundaries, "IN-DUH-KAYT" or "IND-UCK-ATE" or ? A Cockney or a Kiwi or a Cajun might each produce ''and'' voice notations completely differently. But it's better than nothing. And with either bolding (as in here), italicising or uppercase-contrasting-with-the-rest-in-lowercase you can indicate the stressed syllable(s). Maybe look at {{w|Pronunciation respelling for English}} (I didn't see a further link to qualify any 'standards' for this non-phonomic system, and doubt that there are any that travel well beyond any actual particular narrow dialectical territory).
: I actually think it's part of the joke that it's an imprecise 'pronunciation guide', rather than a technically advanced one like /aɪ pʰiː eɪ/ itself is, further confusing the deliberately confused issue. [[Special:Contributions/141.101.99.29|141.101.99.29]] 19:45, 24 July 2021 (UTC)

We teach the impulse-momentum equation f*(delta)t = m*deltaV as FAT MAV. And you're far more likely to hear a mentor remind a student to use 'FAT MAV' than 'the impulse-momentum equation' this comic seemed an obvious evolution that idea. [[User:Sraben|Sraben]] ([[User talk:Sraben|talk]]) 20:54, 25 July 2021 (UTC)

Something similar does indeed happen in reality, when you have to read things like tan y = sinh x, cot y = csch x. Many people read sinh like sin-ch, while some others read it as shine, etc. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 23:22, 17 August 2021 (UTC)

2501: Average Familiarity

2021-08-17T22:59:30Z

Yosei:

{{comic
| number = 2501
| date = August 11, 2021
| title = Average Familiarity
| image = average familiarity.png
| titletext = "How could anyone consider themselves a well-rounded adult without a basic understanding of silicate geochemistry? Silicates are everywhere! It's hard to throw a rock without throwing one!"
| imagesize =
}}

==Explanation==
{{incomplete|Created by A SILICATE (DON'T WE ALL KNOW THE FORMULA?). do NOT delete this tag too soon.}}

This comic claims that experts vastly overestimate how familiar other people are with their own field of study. As an example, [[Randall]] shows a conversation between [[Ponytail]] and [[Cueball]] as two {{w|geochemistry|geochemists}} specializing in {{w|silicate}} chemistry. Although the two scientists understand that the layman does not know all that they know about silicates, they are still under the impression that other people at least know the chemical makeup of {{w|olivine}} and some {{w|feldspar}}s. Cueball also mentions {{w|quartz}}, an even simpler mineral taken for granted by Ponytail.

In truth, the average person can't be expected to know the chemical makeup of ''any'' arbitrarily-chosen substance reliably (or any material at all, if that average person's job and hobby do not involve chemistry — aside from the few that made their way into {{w|common knowledge}}, like NaCl for salt<ref>"NaCl (Sodium Chloride)" Kate & Anna McGarrigle. 2010. Accessed August 17th, 2021. http://www.mcgarrigles.com/music/the-mcgarrigle-hour/nacl-sodium-chloride</ref> ({{w|Halite}}), H2O for water/ice, or CO2 for carbon dioxide), and may not even know the definition of "feldspar" beyond "a mineral", if at all.

It even goes so far as to initially gloss over the 'everyday' knowledge of quartz... until prompted by the slightly-less-overestimating partner in the conversation. Perhaps like a gardener forgetting to mention the lawn he maintains (along with the 'actual' plants in the borders or vegetable patches), there seemed no need to include such a common mineral as a subject of silicate chemistry. Quartz is a basic silicon oxide (SiO2) that many non-chemists ''have'' heard of because it is common and has a variety of uses, though they would not know its chemical structure. Quartz ''can'' be found as distinct large-scale crystals (probably obvious to the layman, as an ice-cube is in a drink) but also features as a hard-wearing micro-constituent of many rocks. Quartz is a major component of most sand (except for coral sands, which are calcium carbonates). Quartz crystals are sometimes made into jewelry and other decorative objects. Most modern clocks use {{w|Crystal oscillator|the resonance frequency of quartz}} to keep time.

Minerals like feldspars and olivine generally exist as a continuum of varying chemical formulas, represented as a mixture of "endmembers" that have some pure composition. Feldspars are a category of aluminum-containing silicate minerals that account for the most of the rock the earth's crust by mass. They are composed of a silicon-aluminum-oxygen lattice filled with sodium, potassium, or calcium ions. The major varieties are CaAl2Si2O8 (anorthite), NaAlSi3O8 (albite), and KAlSi3O8 (potassium feldspar). Olivine is the primary constituent of the upper mantle and has the formula X2+2SiO4, where X is any two calcium or magnesium ions. The ends of the spectrum are Mg2SiO4 ({{w|forsterite}}) and Fe2SiO4 ({{w|fayalite}}).

In the title text the two geologists express belief that the average person ''should'' be more familiar with silicates because of how ubiquitous they are. Their somewhat-exasperated statement plays on the phrase "you can't throw a rock without hitting one," a standard hyperbole about how common something is. Indeed, {{w|Silicate mineral|silicate}} rocks are extremely common on Earth — not only would a rock thrown in a random direction stand a decent chance of striking a silicate mineral rock but the randomly-selected rock being ''thrown'' also has a very high chance of being a silicate mineral rock. With the exception of a few carbonate deposits, rocks found in large deposits on Earth's surface nearly all have silica in them, even extraterrestrial rocks. The Earth's crust is about 60% silica by weight.<ref>"Constraining crustal silica on ancient Earth" C. Brenhin Keller, T. Mark Harrison. ''Proceedings of the National Academy of Sciences'' Sep 2020, 117 (35) 21101-21107; DOI: 10.1073/pnas.2009431117</ref>

==Transcript==
:[Ponytail and Cueball are talking. Ponytail has her hand raised, palm up, towards Cueball.]
:Ponytail: Silicate chemistry is second nature to us geochemists, so it's easy to forget that the average person probably only knows the formulas for olivine and one or two feldspars.
:Cueball: And quartz, of course.
:Ponytail: Of course.

:[Caption below the panel]
:Even when they're trying to compensate for it, experts in anything wildly overestimate the average person's familiarity with their field.

== References ==
<references />

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Geology]]
[[Category:Science]]

2478: Alien Visitors 2

2021-07-16T05:38:11Z

Yosei: /* Explanation */ the natural assumption is 'interstellar' not 'interplanetary', as in 2477 too

{{comic
| number = 2478
| date = June 18, 2021
| title = Alien Visitors 2
| image = alien_visitors_2.png
| titletext = "Although fresh juice DOES sound--" "NO! For humanity to survive we must learn from the mistakes of the past."
}}

==Explanation==

This is the second comic in a [[:Category:Alien Visitors|series]], following the previous comic [[2477: Alien Visitors]].

The aliens now return to show us even more "advanced" inventions. As with the previous strip, the only innovations they offer are not only things that humans know how to build, but things we figured out some time ago, and are now obsolete. As with the pyramids and Stonehenge, these inventions might have been impressive in their time, but now offer nothing to humanity.

{{w|Biplane}}s are planes with two sets of wings, which provide more of the necessary lift at slow speed than a contemporaneous {{w|monoplane}}, but develop increased drag and aerodynamic and air-frame issues as higher air-speeds became possible/necessary. Biplanes have been obsolete for most purposes since the 1930s, though they remain in use for agriculture and aerial sports.

A {{w|blimp}} is a lighter than air aircraft with no internal structure. These aircraft were traditionally filled with hydrogen gas to provide the needed buoyancy, due to the lower density of hydrogen and a US monopoly on helium limiting availability for the German blimp manufacturer. Hydrogen is highly flammable and thus presents a safety issue. The famous {{w|Hindenburg_disaster|''Hindenburg'' disaster}} is widely seen as a reason hydrogen airships are unlikely to be widely accepted. However, it is still disputed whether the hydrogen or the coating of the airframe caused the fire. Blimps are still used today, but only rarely, in niche applications, such as for advertising or for aerial photography/videography. Modern airships generally use helium as a lifting gas, which is more expensive, but non-flammable.

{{w|Tetraethyllead}} ((CH3 CH2)4Pb) is a chemical added to gasoline (mostly from the 1920s to the 1990s — although some countries [https://web.archive.org/web/20171115235249/http://wedocs.unep.org/bitstream/handle/20.500.11822/17542/MapWorldLead_March2017.pdf?sequence=1&isAllowed=y still use it to this day]) to prevent {{w|engine knocking}}. Lead is toxic and bio-accumulative, and there's substantial evidence that its use in gasoline caused widespread lead exposure, impacting public health on a huge scale. While it is unclear whethere this chemical is also harmful to the aliens, they seem surprised to learn of these toxic effects, and their concern implies that they may be using leaded gasoline themselves.

The final invention appears to be a reference to {{w|Juicero}}, a defunct and short-lived brand of juicer, which has become iconic of the absurdity of modern technology investment. The company produced a high-tech, internet-connected juicer which sold for $700, and only worked on the company's proprietary branded single-serving bags of pulped fruit, which were available by subscription for $5-$7 per serving. The company raised over $100 million in startup capital, but quickly went out of business because most consumers considered the expensive product to be nearly useless, coupled with a rather damning [https://www.youtube.com/watch?v=5lutHF5HhVA video by Bloomberg] demonstrating said packets could easily be squeezed by hand. The title text singles this invention out, calling it one of the "mistakes of the past".

After the latest showing of unimpressive "inventions", the humans start questioning how "advanced" the aliens really are. It's traditionally assumed that a species capable of interstellar travel would have a host of other advanced technologies, which is inconsistent with the unimpressive and not only obsolete, but also fatally-flawed inventions they're offering to humanity. The humans on the ground ask whether they actually built their own flying saucer. They also consider the wiseness of standing directly under the saucer, implying that, if the aliens did build it, it's likely to be unreliable, and may be at risk of crashing (though perhaps a bit ironically, the humans say this in response to the juicer, and while the actual device it is spoofing was a failure in many ways, one thing it was ''not'' was shoddily built - one critique of the Juicero was that it was needlessly over-engineered).

==Transcript==
:[A flying saucer is flying high above Ponytail who is walking towards White Hat, Cueball and Megan. Those three are looking up at the spacecraft. The humans are drawn very small standing on the ground beneath it. The aliens inside speak to them from inside their saucer, indicated with zigzag lines between it and the text.]
:Aliens: Greetings, humans. We have returned.
:Aliens: Since you already have pyramids, we've brought you more advanced wonders.

:[Pan up to only showing the flying saucer which has two beams below it, the left showing an outline of a biplane and the right is showing an outline of a blimp. The humans reply off-panel. Given their positions before, the first is probably Ponytail, but it cannot be determined.]
:Aliens: These machines will let you conquer the sky!
:Voice 1 (off-panel): A biplane?
:Voice 1 (off-panel): Aren't monoplanes more efficient?
:Voice 2 (off-panel): Does that blimp use hydrogen?

:[Zoom in on the four humans looking up, the Aliens reply from above the panel. There is a chemical formula in an outline from the alien flying saucer, shown in a similar manner to the other items.]
:Chemical formula: (CH3 CH2)4 Pb
:Aliens (off-panel): Add this elixir of lead to your gasoline and your engines will run smooth.
:White Hat: Lead? Isn't that stuff toxic?
:Aliens: Is it?
:Aliens: Oh no.

:[Zoom back out, as in first panel but the flying saucer and the humans are shown in silhouette. A beam from the saucer is showing an outline of a juice machine.]
:Aliens: Okay, uh.
:Aliens: This device's electric press can squeeze fresh fruit juice from bags of pulp!
:Ponytail: ...Just curious, did you build that saucer?
:Cueball: Maybe we shouldn't stand right under it.

{{comic discussion}}

[[Category:Alien Visitors]]
[[Category:Comics sharing name|Alien Visitors 2]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Aliens]]

1027: Pickup Artist

2021-03-20T14:03:46Z

Yosei: /* Transcript */ own under -> down under

{{comic
| number = 1027
| date = March 9, 2012
| title = Pickup Artist
| image = pickup_artist.png
| titletext = Son, don't try to play 'make you feel bad' with the Michael Jordan of making you feel bad.
}}

==Explanation==
[[Hairy]] and [[Cueball]] are sitting at a table with drinks. Hairy tells Cueball that he's learned some {{w|pickup artist}} tricks. Cueball is appalled, declaring that pickup artists are "dehumanizing creeps". Hairy argues that he's simply learning new tactics such as "[http://www.urbandictionary.com/define.php?term=negging negging]" (undercutting the target's self-esteem so that she'll feel vulnerable and crave approval), evidently oblivious to the fact that he's proving Cueball's point. Rejecting Cueball's advice to simply talk to women "like a fucking human being", Hairy sets off to try out the technique.

Meanwhile, [[Black Hat]] and [[Danish]] are sitting at another table. Black Hat leaves to roll a bowling ball through the restroom stalls to smash the feet of anyone there using them. In North America, public restrooms usually have a 1-foot (30 cm) gap between the floor and the bottom of the stall dividers. As people sit down to use a stall most of the time, their feet would be vulnerable to being hit in sequence. Perhaps Black Hat is going for a 'strike'. Hairy approaches Danish, while Cueball looks on and says "oh no" — seemingly recognizing Danish and anticipating the disaster Hairy is walking into, or perhaps simply not wanting Hairy to use his tricks on anyone.

Hairy makes an attempt at "negging" by suggesting that Danish's fruit plate reflects a need to lose weight. Danish, naturally being a master at psychological manipulation, immediately realizes his game, and crushes him utterly by taking another shot in the psychological dark ([[440: Road Rage]]) — telling him that he's trapped in an endless cycle of failure because he's ultimately a mediocre person and will never do anything of value with his life. Demoralized, Hairy declares that he needs to go home and think about his life; Danish tells him, "It won't help.” (This may be a reference to the "deathsticks" scene in ''Star Wars: Attack of the Clones''.) Of course, once Black Hat discovers his shenanigans, Hairy might not have much more life to rethink.

The title text refers to {{w|Michael Jordan}}, a very popular and accomplished {{w|basketball}} player who played for the {{w|Chicago Bulls}} and the {{w|Washington Wizards}}. His name is often used as a noun to denote that someone is the best in their field, which is later used in [[1120: Blurring the Line]].

The pick up subject and Hairy returned in [[1178: Pickup Artists]], where he tries to improve his skills (which he must have felt he needed after this experience), by hanging out with other pickup artists, thus the plural version of the comic title. This comic is one of a small set of comics with the same or almost the same title as another comic (only plural form of artist the difference).

==Transcript==
:[Hairy and Cueball sitting at a table.]
:Hairy: I've been learning tricks from pickup artist forums.
:Cueball: Pickup artists are dehumanizing creeps who see relationships as adversarial and women as sex toys.

:[Close-up of Hairy's head, with a faint outline of Black hat and Danish sitting at a table in the background.]
:Hairy: No, it's just a bunch of tips! Like ''negging'': you belittle chicks to undermine their self-confidence so they'll be more vulnerable and seek your approval.

:[Close-up of Cueball's head.]
:Cueball: Just talk to them like a fucking human being.
:Hairy: Nah, that's a sucker's game.
:Hairy: Ok— wish me luck!

:[Small frame across top of panel reads ''Meanwhile...'' and Danish is sitting at a table with Black hat standing next to the table holding a bowling ball under his arm.]
:Black Hat: I'm going to the bathroom to roll a bowling ball down under the line of stalls.
:Danish: Cool.

:[Close up of Cueball's head, with Hairy approaching Danish's table in the background.]
:Cueball: Oh no.

:[Hairy and Danish at a table. Hairy is standing up and leaning on the table.]
:Hairy: You look like you're on a diet. That's great!
:Hairy: How's the fruit plate?

:[Close-up of Danish's head.]
:Danish: Ooh- are we negging?
:Danish: Let me try!

:[Close-up of Danish's head, with her hand raised.]
:Danish: You look like you're going to spend your life having one epiphany after another, always thinking you've finally figured out what's holding you back, and how you can finally be productive and creative and turn your life around.
:Danish: But nothing will ever change. That cycle of mediocrity isn't due to some obstacle. It's who you ''are''.
:Danish: The thing standing in the way of your dreams
:Danish: is that the person having them is ''you''.

:[Hairy and Danish at a table. Hairy is standing up.]
:Danish: Ok, your turn! Ooh, try insulting my hair!
:Hairy: I think I need to go home and think about my life.
:Danish: It won't help.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Danish]]
[[Category:Comics featuring real people]]
[[Category:Romance]]
[[Category:Comics sharing name|Pickup Artist01]]

Talk:2350: Deer Turrets

2021-03-20T14:01:33Z

Yosei: “Deer are well-defined”?

There's no "next" button on [[2349]]? --[[Special:Contributions/108.162.219.250|108.162.219.250]] 18:44, 24 August 2020 (UTC)
:The reason there's no Next button is that it's the newest comic. --[[Special:Contributions/162.158.158.43|162.158.158.43]] 21:04, 24 August 2020 (UTC)

Is this about something? I mean, it could be a commentary on the way politics handled Covid, some politicians taking terrible decisions, then saying it was a mistake and that science is still learning, but then still taking terrible decisions afterwards. [[Special:Contributions/141.101.69.83|141.101.69.83]] 21:02, 24 August 2020 (UTC)

:That's definitely my take on this comic. The similarity with certain political meetings in the covid situation is quite abvious, in my opinion. [[Special:Contributions/90.127.120.72|90.127.120.72]] 16:02, 25 August 2020 (UTC)

:I saw it as a send up of the agile development practices of Silicon Valley and many other businesses today. The principle is that if an idea is going to fail, you want it to fail fast, so you can learn and pivot quickly to a better idea. This can ideally result in a culture that values constructive failure. If taken too far, it can lead to sloppy practices, waste, and outright harm to customers and to the public. [[User:JSekula71|JSekula71]] ([[User talk:JSekula71|talk]]) 20:12, 27 August 2020 (UTC)

The thing about icebergs, is that 9/10ths of them would be ''on fire'', if they weren't kept underwater. Truth! [[Special:Contributions/162.158.155.192|162.158.155.192]] 22:17, 24 August 2020 (UTC)

(to the tune of “Do-Re-Mi”) ''Does are near, now flee in fear; The ray will boil everyone; The antlered gun is taking aim; Now it’s vaporised my lung...'' [[User:Lightcaller|Lightcaller]] ([[User talk:Lightcaller|talk]]) 22:43, 24 August 2020 (UTC)

Deer don't gallop. Are you sure that's about the deer? [[Special:Contributions/172.69.33.187|172.69.33.187]] 22:54, 24 August 2020 (UTC) Dear IP_address, deer most certainly do gallop. Since I'm a nice guy (rarely), I LMGTFYed that to confirm. [[User:Cellocgw|Cellocgw]] ([[User talk:Cellocgw|talk]]) 12:35, 25 August 2020 (UTC)
:No deer run. [[Special:Contributions/172.69.34.210|172.69.34.210]] 02:25, 26 August 2020 (UTC)
:Some deer run. [[Special:Contributions/162.158.159.116|162.158.159.116]] 16:04, 24 September 2020 (UTC)

I don't think you can build an iceberk-proof airship. Or at least, you won't get it into air because it would be too heavy. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 00:21, 25 August 2020 (UTC)

You make a ship iceberg proof by making it fly. You can't be sunk if you fly over. [[User:Hax|Hax]] ([[User talk:Hax|talk]]) 07:16, 25 August 2020 (UTC)

I think the "Is it really??" means "Is it really okay?", not "Is it really a mistake?". [[Special:Contributions/162.158.183.137|162.158.183.137]] 11:03, 25 August 2020 (UTC)

Gotta keep on trying 'til you run out of cake. [[Special:Contributions/108.162.210.188|108.162.210.188]] 13:18, 25 August 2020 (UTC)

Some airplanes crash into mountains. Some mountains look like icebergs. Therefore, some airplanes crash into some icebergs. [[User:These Are Not The Comments You Are Looking For|These Are Not The Comments You Are Looking For]] ([[User talk:These Are Not The Comments You Are Looking For|talk]]) 03:51, 1 September 2020 (UTC)

The current explanation says, “Deer are well-defined by their tendency to move around” - though I’m not too familiar with deer (they’re not common animals in my place), I’m not sure if this explanation is okay. Maybe “well-known” instead of “well-defined”? Intuitively, the set {A | A has tendency to move around} is not well-defined... [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 14:01, 20 March 2021 (UTC)

== When Mao went to clear the sparrow but for the locust, it was 42% as deadly as fauna-mounted autocannons ==

Just saying. [[Special:Contributions/172.69.34.150|172.69.34.150]] 07:17, 25 August 2020 (UTC)

Didn't the designer of the Titanic go down with ship? SanFranSam [[Special:Contributions/172.69.35.53|172.69.35.53]] 04:25, 26 August 2020 (UTC)

== Laughed ==

The part that made me laugh the hardest was the Citation Needed on the claim that there are no flying icebergs! Well played.
[[User:BlakeFelix|BlakeFelix]] ([[User talk:BlakeFelix|talk]]) 11:03, 26 August 2020 (UTC)

2329: Universal Rating Scale

2020-08-20T02:26:13Z

Yosei: /* Explanation */ clarification about the origin of S

{{comic
| number = 2329
| date = July 6, 2020
| title = Universal Rating Scale
| image = universal_rating_scale.png
| titletext = There are plenty of finer gradations. I got 'critically endangered/extinct in the wild' on my exam, although the curve bumped it all the way up to 'venti.'
}}

==Explanation==
{{incomplete|Created by an OFFENDED NUMBER NINE. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
In this comic, [[Randall]] has blended many traditional rating scales to create a "universal rating scale". Unfortunately, the mixing of these scales creates a scale that is impossible to use. Only a subset of the values of each rating scale is included, further weakening its claim as a "universal" scale. The result is much like the attempt to create a "universal standard" in [[927: Standards]].

Alternatively, it can be perceived as a way of comparing the different scales, for instance to answer a question like "Is it worse to get a 2 or an F?"

: '''Scale of zero to ten''' (but with an 11, because people often add that to exaggerate - see {{w|up to eleven}} about the meme)
:: 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 11. The number 9 is omitted, possibly because seven ate nine (789) or because nine is the [[1103: Nine|neglected number]].
: '''Competitive scores''', such as for artistic gymnastics' {{w|Code of Points (artistic gymnastics)|Code of Points}}, (ordinarily from 0.0 to a {{w|Perfect 10 (gymnastics)|perfect 10.0}})
:: 10.0
: '''{{w|Likert scale}}'''
:: strongly disagree, disagree, agree, strongly agree (often there is a "neither agree nor disagree" value in the middle, but it is not strictly required)
: '''{{w|School grades}}''' (there are also B, C, D, and others with + or -)
:: F, A+
:: S - Schools in Japan may use the {{w|Academic grading in Japan|S grading}}, which is said to stand for ''Superior'' [https://en.wiktionary.org/wiki/S#Etymology_1_2], implying “even better than A.” The expression S is also used in daily life, generally perceived as S as in '''S'''pecial or '''S'''uper [https://ja.wikipedia.org/wiki/S#%E3%81%9D%E3%81%AE%E4%BB%96], here unrelated to the academic grading system. For example, the most expensive seat in a theater (e.g. a balcony seat) may be called ''S-seki'' (lit. “S seat”) in Japanese, while the second most expensive seat may be called ''A-seki''. Many video games also use S grading, and some (such as Beat Saber and Dance Dance Revolution) use SS, SSS, and even more S's as ranks above that (though these are not shown in the webcomic). A possibly related expression is “Super S” as in {{w|Sailor Moon (TV series)|''Sailor Moon SuperS''}}.
: '''{{w|Star (classification)|Star rating}}'''
:: 1 star, 2 stars, 3 stars, 4 stars, frequently used to rate restaurants, films etc. 5 star is omitted, probably due to Randall's opinion that items with 5 stars tend to only have had one rater and aren't trustworthy, see also [[1098: Star Ratings]].
: '''{{w|Conservation status}}''' (this is only a subset of the nine groups in the {{w|International Union for Conservation of Nature}} (IUCN) Red List of Threatened Species)
:: extinct, critical (probably ''critically endangered''), endangered, least concern
:: According to the title text, "extinct in the wild" is a half-step below "critical", presumably above "G".
: '''{{w|Starbucks#Products|Starbucks brand beverage sizes}}''' (there is also short and trenta)
:: tall, grande, venti
: '''MPAA age-appropriate {{w|Motion Picture Association film rating system|film ratings}}''' took effect November 1, 1968 with G, M (now PG), R (not shown in comic) and X (now NC-17)
:: G, PG (as of February 11, 1972, replaced GP), {{w|PG-13}} (introduced July 1, 1984), {{w|NC-17}} (introduced September 1990, replaced X)
: '''ESRB age-appropriate {{w|Entertainment_Software_Rating_Board#Ratings|ratings}}''' for video games (there is also EC for early childhood, E for everyone, E10+ for Everyone 10+, M for Mature, and AO for Adults Only)
:: T for teen
: '''Happiness emojis''' (alternately, the '''{{w|Wong–Baker Faces Pain Rating Scale}}''')
:: Frowny face (☹, U+2639), neutral face (😐, U+1F610), smiley face (☺, U+263A). It is not totally clear which emoji each symbol is meant to refer to. The unhappy face could be [https://emojipedia.org/worried-face Worried Face] 😟, [https://emojipedia.org/anguished-face/ Anguished Face] 😧, [https://emojipedia.org/frowning-face/ Frowning Face] ☹️ (note the lack of eyebrows), [https://emojipedia.org/slightly-frowning-face/ Slightly Frowning Face] 🙁 etc.
: '''{{w|Coin grading|Coin grades}}'''
:: G, VG, UNC for good, very good, uncirculated
: '''Hurricane/cyclone strengths''', {{w|Saffir–Simpson scale}} (ordinarily categorized from category 1 to category 5)
:: Category 5
: '''Tornado intensities''', {{w|enhanced Fujita scale}} (ordinarily categorized from EF0 to EF5)
:: EF-5
: '''Credit (and other) ratings'''
:: A, AA, AAA
:: Credit rating agencies will rank businesses and governments based on their likely ability to pay back their creditors' interest ratings. The very highest are rated AAA, and then (in Standard & Poor's scheme) AA+, AA, AA-, A+, and so on. (Note that Randall's scale rates A+ as better than AA, indicating that it's the "A+" from school grades rather than the one from Standard & Poor's list.)
:: Could also be a reference to battery sizes, this would imply that AAA is better than AA, which is not necessarily true, but funny to think about.
:: Alternatively, this could be a reference to sports tier divisions; where AA and AAA basketball for example promote age and skill appropriate competition.
=== Title text ===
The title text suggests that the scale as shown here is incomplete, by referencing further gradings that are not shown in the table. {{w|Critically endangered}} and {{w|Extinct in the wild}} are real conservation status categories recognised by the IUCN, although it's not clear what "Critically endangered/extinct in the wild" would mean - perhaps the "possibly extinct in the wild" designation, abbreviated CR(PEW). It would presumably fit on the table somewhere between "Extinct" and "Critical", although its ordering relative to "tall", "2" and "G" is unclear.

The title text suggests that a score at this level had been {{w|Grading on a curve|graded on a curve}}, which bumped its rating up to "Venti", which is on the table, two steps below "Least concern". This would be an extraordinary example of such a curve, pushing the score from approximately 2/10 to almost 8/10. This could only happen if the exam was extremely difficult, meaning most results were significantly below 2/10.

==Transcript==
: [Caption above the frame:]
: Universal Rating Scale
:
: [A vertical scale, with 45 gradations, labeled]
: 0
: 1
: Strongly Disagree
: F
: [star] ☆
: Extinct
: Tall
: 2
: G
: Critical
: [frowny face] ☹
: 3
: endangered
: [two stars] ☆☆
: PG
: Disagree
: VG
: 4
: Grande
: 5
: PG-13
: [neutral face] 😐
: 6
: T for Teen
: 7
: [three stars] ☆☆☆
: Agree
: Venti
: 8
: Least Concern
: [smiley face] ☺
: A
: Strongly Agree
: Category 5
: EF-5
: NC-17
: UNC
: AA
: [four stars] ☆☆☆☆
: A+
: S
: AAA
: 10
: 10.0
: 11

{{comic discussion}}
[[Category:Charts]]

Talk:2293: RIP John Conway

2020-04-20T18:05:08Z

Yosei: PS

This is really very impressive. The design of the stick figure to allow it to release a glider that ascends upwards (the "soul" rising to "heaven" or whatever) with the body decaying - that's a hard thing to get right using just the Game of Life rules. [[Special:Contributions/172.69.68.175|172.69.68.175]] 17:49, 13 April 2020 (UTC)
:Although Randall is clever, the Game of Life has been studied for so long that I'm sure this is a well-known animation. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 18:29, 13 April 2020 (UTC)
:: I played with the game a bunch in the past, but I've only done a bit of research after this appeared. I don't immediately find any previous report of this starting arrangement
:: This is unlikely, as the Game of Life has an uncountable number of patterns of this size, some of which are still being discovered. The pattern above is 7 cells wide by 9 cells tall - the number of distinct patterns that can be drawn in that box nears 2 --> 60 --> 1 (2^60). It's most likely that patterns such as this one are commonplace, and Randall just fiddled around until he reached one that he desired. The pattern itself, however, has likely never been discovered before. (As a fun postscript, [http://catagolue.appspot.com/object/xp16_0c2w3vz33032988/b3s23 a notable 8-cell wide, 9-cell tall pattern oscillating at period 16], just slightly larger than the one above, was discovered in February 2020.)[[User:Hdjensofjfnen|Hdjensofjfnen]] ([[User talk:Hdjensofjfnen|talk]]) 21:31, 13 April 2020 (UTC)
:::I suspect it's probably more likely that he worked it out backwards, rather than "just fiddled with it." [[Special:Contributions/108.162.216.244|108.162.216.244]] 04:24, 14 April 2020 (UTC)
::::AFAIK, many CAs such as Life have the property of being irreversible, which is the entire point for various pattern search efforts.[[Special:Contributions/162.158.92.54|162.158.92.54]] 07:13, 14 April 2020 (UTC)
:::::He probably started with the floater, and adjusted the rest so it wouldn't interfere. Most figures decay in the game of life (I learned when playing with it, decades ago) --[[Special:Contributions/162.158.111.79|162.158.111.79]] 10:45, 14 April 2020 (UTC)
:::::The Game of Life has been researched a lot. One sub-problem is finding an arrangement of cells that cannot be produced by a prior arrangement of cells. They are called Garden of Eden patterns, and the known ones are not small. Glider generators are rather common, so it is most likely that the initial pattern was created by working backward from an existing glider generator.[[Special:Contributions/173.245.54.125|173.245.54.125]] 17:33, 14 April 2020 (UTC)
:::I like the comment above by Hdjensofjfnen, where 2^60 is written using [https://en.wikipedia.org/wiki/Conway_chained_arrow_notation Conway’s chained arrow notation]. That’s a slick way to honor Conway. Anyway, when the number of possible candidates is around 2^64 or less, you can find a desired solution by brute-force search if you have to, provided that the problem is relatively simple and well-defined (i.e. if you can write an efficient program). In this case, the number of the candidates of the initial state is very small, if it should be a tiny, pixel image of a stick figure. So, intuitively, an exhaustive search should be easy—at least it should be doable. (PS: I mean, the idea of this comic is cool and awesome; it’s not trivial at all for you to come up with this. But if you do come up with this problem, then the solution may not be so difficult.) [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 17:35, 20 April 2020 (UTC)

was there a placeholder comic posted before the gif went live?

:I am certain there was one with "uh oh one of the lights went out" "that's not supposed to happen" and a picture of a pattern that I did not recognise, which I found to be quite sad. [[Special:Contributions/162.158.92.54|162.158.92.54]] 10:35, 14 April 2020 (UTC)

::This was SMBC, and the pattern is a glider generator. [[Special:Contributions/188.114.111.211|188.114.111.211]] 12:30, 14 April 2020 (UTC)

Looks like this is second animated comic in xkcd, besides 1116(though 1190 could be possibly counted together) [[Special:Contributions/172.69.190.16|172.69.190.16]] 19:34, 13 April 2020 (UTC)
:Uh, [[1331: Frequency]] and [[1264: Slideshow]] immediately come to mind, and then I remember about [[961: Eternal Flame]]. There's a lot more than two. [[User:Volleo6144|Volleo6144]] ([[User talk:Volleo6144|talk]]) 19:43, 13 April 2020 (UTC)
::[[:Category:Comics with animation]]; just added it. [[User:Yngvadottir|Yngvadottir]] ([[User talk:Yngvadottir|talk]]) 20:19, 13 April 2020 (UTC)

The explanation says that the simulation is run on an infinite grid, but even when the grid is calculated out beyond the border of the viewable area, bounding errors & boundary formations can occur. I've never seen ''any'' implementation that actually produces an infinite, nor even ''practically'' infinite grid. (In fact, wasn't there a Minecraft mod that runs until it lags out the engine?) Can anybody point me to a truly infinite grid implementation? Conway's ''definitely'' was not infinite, he even commented at length about the boundary formations that show up at the grid edges (which are among the most subjectively beautiful, incidentally). I think the explanation needs correction?
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 21:59, 13 April 2020 (UTC)
: The explanation is describing Conway's game of life, not any particular implementation IMHO. No change needed IMHOA. Also, the previous post was not signed properly. [[Special:Contributions/162.158.107.167|162.158.107.167]] 21:47, 13 April 2020 (UTC)
::Except many of Conway's observations about the "game" & even ''his initial description'' of it explicitly state & indeed hinge upon the fact that it's not (& thus far ''cannot'' be) implemented as an "infinite" grid. Part of the whole point of his experiment with it & the various demonstrations is to illustrate edge effects resulting from a finite range of calculations. '''It's extremely relevant that it's''' '''''not''''' '''infinite.''' It's actually kinda the whole point of his creating it, much the same way people working with fractals likewise tend to become very interested in bounding errors. The boundaries are where the interesting work is done. Apparently someone agreed with me at least in part, because they edited the wording. Thanks... Brian? I think we should actually '''add''' to the description of the "game" info highlighting the edge effects, because that's the primary focus of the project & its outgrowths in the first place. (We can't adequately simulate infinity & that's a big part of the interest in it.) Also, I frequently have to submit & then refresh & sign afterward because of the device I'm on. In this case I'm glad I did, because I saw your reply & the other new stuff!
::[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 22:17, 13 April 2020 (UTC)
:Golly uses a grid of arbitrary size by default. It can very easily be verified to at least ±210000. (Note that it also includes finite rectangular and toroidal grids.) [[User:LegionMammal978|LegionMammal978]] ([[User talk:LegionMammal978|talk]]) 01:39, 14 April 2020 (UTC)
:Winning Ways, p. 817 (3rd printing): 'Life is a "game" played on an infinite squared board.'--[[Special:Contributions/172.68.54.208|172.68.54.208]] 13:45, 17 April 2020 (UTC)
No computer [Citation Needed] can run an ''actual'' infinite grid, but with some intelligent bounding you can mitigate early signs of problems by maintaining "bubbles" of cells with offsets. You get into problems once you start machine-gunning out gliders (offsets will eventually overflow or awkwardly lose precision, depending on the var-types used; and maintaining a longer and longer bubble, or more and more bubbles just above glider-sized, is probably your other challenge) but it's probably good enough for most purposes. If you somehow have finite patterns that move out in huge (wasteless) cycles from the 'origin' and hold that path until enacting hugely-delayed doglegs (mathematically, it must be a point no further away than can be reasonably enumerated by the bits of information contained within each formation, and significantly less as it'd be a far less efficient count-down cycler than any folded LFSR, but it's ''imaginable'') to meet again at some arbitrary (though deterministic and replicable) distance out in the far far reaches of your abstracted bubble-land then it's possible you could ''pretend'' you have infinite space. [[Special:Contributions/162.158.91.101|162.158.91.101]] 22:26, 13 April 2020 (UTC)
[[User:ProphetZarquon|ProphetZarquon]], do you have a source for your claim that the main point of Conway's creation of Life was to study the edge effects? [https://conwaylife.com/wiki/Conway%27s_Game_of_Life The page for Life on its own wiki] describes the Life grid as "infinite" and only mentions edge effects as inaccuracies to be avoided, and [https://www.youtube.com/watch?v=R9Plq-D1gEk this Conway interview about Life's creation] doesn't mention edges at all.
[[Special:Contributions/108.162.241.24|108.162.241.24]] 23:34, 13 April 2020‎ (UTC)
:First of all, as a tip, reply directly to the comment when you want to talk with someone. Secondly, yeah, I'm pretty sure that person's just blasting ass ham. [[Special:Contributions/172.69.69.28|172.69.69.28]] 02:49, 14 April 2020 (UTC)

Possibly worth noting is the bit of artistry in the rendering. Munroe alters the step period of the iterations so that the deconstruction of the humanoid shape happens more quickly, with the stepping of the glider translating away occurring more slowly. [[User:Fixer|Fixer]] ([[User talk:Fixer|talk]]) 21:52, 13 April 2020 (UTC)

I like the comic very much, and I'm afraid to say I hadn't heard of his death in amongst... well, everything else. RIP.
While I'm here, though, I'm a bit concerned about the current cell generation cycle explanation, as it feels awkward. Currently it is (paraphrased) "live cells survive if just enough neighbours / dead cells come to life with exactly enough neighbours / any other dies or stays dead". I'd prefer something that more delineates it as birth (dead to live, by propogation from the right number of live neighbours), death (live to dead due to ''either'' isolation ''or'' overcrowding) and continuation of state in all other cases. Can't work out a good phrasing yet, but ''may'' try it out later. [[Special:Contributions/162.158.91.101|162.158.91.101]] 22:26, 13 April 2020 (UTC)
: Agreed 100%. I believe the problem lies in the confusion between "cell as in biology" versus "cell as in jail". It would be better to avoid the word "cell" and describe a grid with squares that are either inhabited or empty; inhabitants with two or three neighbours survive to the next generation, otherwise they die (square becomes empty the next generation); exactly three neighbours to an empty square will give birth (become inhabited) in the next generation; and any other empty square stays empty.

Given the cause of death, should this comic be listed among the Covid-19 series? [[User:Momerath|Momerath]] ([[User talk:Momerath|talk]]) 05:02, 14 April 2020 (UTC)
:Yes.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 10:51, 14 April 2020 (UTC)
:No. This is about John Conway. It would have presumably run regardless of the cause of death.

Interesting to see if the next comic is also a Covid-19 comic, because then it will be the 19th covid-19 comic... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 10:53, 14 April 2020 (UTC)

I really think this should not be regarded as a Covid-19 comic, since it's a memorial one and the cause of death is not important for this comic. [[Special:Contributions/162.158.93.105|162.158.93.105]] 14:18, 14 April 2020 (UTC)
:Agree with the others, this is a memorial comic, NOT a COVID-19 comic. I feel like too many comics are being forced into the COVID-19 theme, when they have little to no relation. [[Special:Contributions/172.69.22.62|172.69.22.62]] 16:12, 14 April 2020 (UTC)
::Covid-19 is obviously not directly the topic of the comic, but it is related quite close. So I vote to re-add it to the category, but to put the mention of the connection with the other comics not into the explanation, or on its bottom. If this is acceptable, [[961: Eternal Flame]] should also be included to [[:Category:Cancer]]. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 10:43, 15 April 2020 (UTC)
:::Of course this is one in the Covid series. Randall very rarely makes tributes and it has been 5 year since the last. Conway is not very famous, and had he died a year ago, chances are Randall would not have made this comic. But because he died of Covid while all Randall's comics is about Covid he makes a tribute now. For the same reason I do not think that Eternal flame has anything with the cancer category. Because this was a tribute Randall made without any connection to a series of cancer comics. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 11:25, 15 April 2020 (UTC)
::::Thanks for correcting my spelling errors :D all of that is speculation. How do you know, that Randall is not a huge Conway fan? seems to play exactly into his geekynes. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 12:47, 15 April 2020 (UTC)
:::::I also disagree that Randall is not a huge Conway fan. I believe he would be familiar and interested in the Game of Life automata, as a nerd/geek. It was previously mentioned over 10 years ago in [[696: Strip Games]]. I agree with Lupo's suggestions for this comic. [[Special:Contributions/172.69.34.44|172.69.34.44]] 17:01, 15 April 2020 (UTC)

== Is this original? ==

It would seem remarkable if Randall was able to create this starting pattern at such short notice. If it's copied from somewhere, we should provide that detail. [[User:Stevage|Stevage]] ([[User talk:Stevage|talk]]) 03:54, 15 April 2020 (UTC)
:I do not know if it is taken from another place or a common/known pattern (the comments above seem to suggest otherwise), but it is not uncommon to have an obituary / memorial in stock for elderly persons of relevance. So it might be possible, that e.g. Randall played around with putting stick figures into a simulation, and accidently found this, deciding to keep it somewehere in his archive for this occasion. The seperation of the decaying body and the everlasting part going upward is actually obvious enough to connect with the idea to use it for this occasion. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 10:36, 15 April 2020 (UTC)

== First popularized? ==

The game's popularization "to the general public" in Windows 3.1 really depends on your definition of popular - how many members of the general public had PCs then? I mention this to point out that it was really Martin Gardner's article in SciAm in October 1970 that showed the game to a pretty wide public, although admittedly few people were in a position to program it at the time. As I maintained the University of Cambridge's version on the PDP-7 (then their only computer with a graphics display) in 1971-72 I'm still astonished at how early this publication was. Gardner then did the same for the Mandelbrot Set (which originated in the Other Cambridge...) [[Special:Contributions/162.158.78.74|162.158.78.74]] 04:23, 16 April 2020 (UTC)

== Leaving the grid ==
<blockquote>"However, any given Game of Life is on a finite grid, so once the glider leaves the grid, it has ceased to exist."</blockquote>

Maybe a philosophical nitpick, but I'd like to dispute this. I submit that it is not possible for anything to "leave the grid". A glider can certainly hit the boundary of a bounded grid, but at that point boundary conditions disrupt the pattern and it ''ceases to be a glider''; thus, gliders cannot leave the grid.

Additionally, the grid can be finite and yet still have no boundary; it is quite common for Life grids to wrap one side of the screen to the other. On such a grid, the glider would in fact persist indefinitely. [[User:Hawthorn|Hawthorn]] ([[User talk:Hawthorn|talk]]) 09:18, 16 April 2020 (UTC)
:Also we don't know if the grid maybe is larger than the screen shown in the comic. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 11:36, 16 April 2020 (UTC)

== Triple whammy ==
FYI: Richard Guy, who found the glider first, and is coauthor of Winning Ways with Conway, already died this March. In the biblical age of 103, so possibly nobody even bothered to check for the cause. (The third author, Elwyn Berlekamp, died a year ago.) [[Special:Contributions/141.101.77.32|141.101.77.32]] 18:02, 16 April 2020 (UTC)

== Conway was not a fan of his fame for Life ==

" He’d like to remembered for any of his accomplishments except the Game of Life. He once said he checked the index of every book and if it listed the Game of Life he would refuse to read it." -- https://twitter.com/standupmaths/status/1249105201992171522 [[Special:Contributions/172.69.22.146|172.69.22.146]] 00:04, 17 April 2020 (UTC)

== Conway died on a Doomsday ==

The thing I remember Conway for (in addition to Game of Life) is discovering the Doomsday rule/algorithm for determining days of the week (see https://en.wikipedia.org/wiki/Doomsday_rule). Of course, I'm nowhere near anywhere as fast as he is (I'm happy if I can do it without making a mistake in 10 seconds, more if I'm calculating under the influence). I find it fitting that Conway died on a Doomsday (Saturday for 2020).[[User:Tovodeverett|Tovodeverett]] ([[User talk:Tovodeverett|talk]]) 05:41, 17 April 2020 (UTC)
:Trivia: I was introduced to Conway's Game of Life through the book "The Magic of Lewis Carroll", by John Fischer (1973). One of the Life patterns was the "Cheshire Cat", which was a cat-like face that became a smile, then a paw-print (2x2 stable block). Conway developed the Doomsday algorithm from Lewis Carroll's initial formula, primarily by noting the even month pattern (4/4, 6/6, 8/8, 10/10, 12/12) and the 9 to 5 at 7-11 mnemonic.[[Special:Contributions/172.69.63.191|172.69.63.191]] 13:17, 17 April 2020 (UTC)
:Trivia: More trivia - April 11, 2020 was 42 days after Feb 29, 2020.[[User:Tovodeverett|Tovodeverett]] ([[User talk:Tovodeverett|talk]]) 04:39, 18 April 2020 (UTC)

Talk:2293: RIP John Conway

2020-04-20T17:35:49Z

Yosei: brute-force search is probably easy

This is really very impressive. The design of the stick figure to allow it to release a glider that ascends upwards (the "soul" rising to "heaven" or whatever) with the body decaying - that's a hard thing to get right using just the Game of Life rules. [[Special:Contributions/172.69.68.175|172.69.68.175]] 17:49, 13 April 2020 (UTC)
:Although Randall is clever, the Game of Life has been studied for so long that I'm sure this is a well-known animation. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 18:29, 13 April 2020 (UTC)
:: I played with the game a bunch in the past, but I've only done a bit of research after this appeared. I don't immediately find any previous report of this starting arrangement
:: This is unlikely, as the Game of Life has an uncountable number of patterns of this size, some of which are still being discovered. The pattern above is 7 cells wide by 9 cells tall - the number of distinct patterns that can be drawn in that box nears 2 --> 60 --> 1 (2^60). It's most likely that patterns such as this one are commonplace, and Randall just fiddled around until he reached one that he desired. The pattern itself, however, has likely never been discovered before. (As a fun postscript, [http://catagolue.appspot.com/object/xp16_0c2w3vz33032988/b3s23 a notable 8-cell wide, 9-cell tall pattern oscillating at period 16], just slightly larger than the one above, was discovered in February 2020.)[[User:Hdjensofjfnen|Hdjensofjfnen]] ([[User talk:Hdjensofjfnen|talk]]) 21:31, 13 April 2020 (UTC)
:::I suspect it's probably more likely that he worked it out backwards, rather than "just fiddled with it." [[Special:Contributions/108.162.216.244|108.162.216.244]] 04:24, 14 April 2020 (UTC)
::::AFAIK, many CAs such as Life have the property of being irreversible, which is the entire point for various pattern search efforts.[[Special:Contributions/162.158.92.54|162.158.92.54]] 07:13, 14 April 2020 (UTC)
:::::He probably started with the floater, and adjusted the rest so it wouldn't interfere. Most figures decay in the game of life (I learned when playing with it, decades ago) --[[Special:Contributions/162.158.111.79|162.158.111.79]] 10:45, 14 April 2020 (UTC)
:::::The Game of Life has been researched a lot. One sub-problem is finding an arrangement of cells that cannot be produced by a prior arrangement of cells. They are called Garden of Eden patterns, and the known ones are not small. Glider generators are rather common, so it is most likely that the initial pattern was created by working backward from an existing glider generator.[[Special:Contributions/173.245.54.125|173.245.54.125]] 17:33, 14 April 2020 (UTC)
:::I like the comment above by Hdjensofjfnen, where 2^60 is written using [https://en.wikipedia.org/wiki/Conway_chained_arrow_notation Conway’s chained arrow notation]. That’s a slick way to honor Conway. Anyway, when the number of possible candidates is around 2^64 or less, you can find a desired solution by brute-force search if you have to, provided that the problem is relatively simple and well-defined (i.e. if you can write an efficient program). In this case, the number of the candidates of the initial state is very small, if it should be a tiny, pixel image of a stick figure. So, intuitively, an exhaustive search should be easy—at least it should be doable. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 17:35, 20 April 2020 (UTC)

was there a placeholder comic posted before the gif went live?

:I am certain there was one with "uh oh one of the lights went out" "that's not supposed to happen" and a picture of a pattern that I did not recognise, which I found to be quite sad. [[Special:Contributions/162.158.92.54|162.158.92.54]] 10:35, 14 April 2020 (UTC)

::This was SMBC, and the pattern is a glider generator. [[Special:Contributions/188.114.111.211|188.114.111.211]] 12:30, 14 April 2020 (UTC)

Looks like this is second animated comic in xkcd, besides 1116(though 1190 could be possibly counted together) [[Special:Contributions/172.69.190.16|172.69.190.16]] 19:34, 13 April 2020 (UTC)
:Uh, [[1331: Frequency]] and [[1264: Slideshow]] immediately come to mind, and then I remember about [[961: Eternal Flame]]. There's a lot more than two. [[User:Volleo6144|Volleo6144]] ([[User talk:Volleo6144|talk]]) 19:43, 13 April 2020 (UTC)
::[[:Category:Comics with animation]]; just added it. [[User:Yngvadottir|Yngvadottir]] ([[User talk:Yngvadottir|talk]]) 20:19, 13 April 2020 (UTC)

The explanation says that the simulation is run on an infinite grid, but even when the grid is calculated out beyond the border of the viewable area, bounding errors & boundary formations can occur. I've never seen ''any'' implementation that actually produces an infinite, nor even ''practically'' infinite grid. (In fact, wasn't there a Minecraft mod that runs until it lags out the engine?) Can anybody point me to a truly infinite grid implementation? Conway's ''definitely'' was not infinite, he even commented at length about the boundary formations that show up at the grid edges (which are among the most subjectively beautiful, incidentally). I think the explanation needs correction?
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 21:59, 13 April 2020 (UTC)
: The explanation is describing Conway's game of life, not any particular implementation IMHO. No change needed IMHOA. Also, the previous post was not signed properly. [[Special:Contributions/162.158.107.167|162.158.107.167]] 21:47, 13 April 2020 (UTC)
::Except many of Conway's observations about the "game" & even ''his initial description'' of it explicitly state & indeed hinge upon the fact that it's not (& thus far ''cannot'' be) implemented as an "infinite" grid. Part of the whole point of his experiment with it & the various demonstrations is to illustrate edge effects resulting from a finite range of calculations. '''It's extremely relevant that it's''' '''''not''''' '''infinite.''' It's actually kinda the whole point of his creating it, much the same way people working with fractals likewise tend to become very interested in bounding errors. The boundaries are where the interesting work is done. Apparently someone agreed with me at least in part, because they edited the wording. Thanks... Brian? I think we should actually '''add''' to the description of the "game" info highlighting the edge effects, because that's the primary focus of the project & its outgrowths in the first place. (We can't adequately simulate infinity & that's a big part of the interest in it.) Also, I frequently have to submit & then refresh & sign afterward because of the device I'm on. In this case I'm glad I did, because I saw your reply & the other new stuff!
::[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 22:17, 13 April 2020 (UTC)
:Golly uses a grid of arbitrary size by default. It can very easily be verified to at least ±210000. (Note that it also includes finite rectangular and toroidal grids.) [[User:LegionMammal978|LegionMammal978]] ([[User talk:LegionMammal978|talk]]) 01:39, 14 April 2020 (UTC)
:Winning Ways, p. 817 (3rd printing): 'Life is a "game" played on an infinite squared board.'--[[Special:Contributions/172.68.54.208|172.68.54.208]] 13:45, 17 April 2020 (UTC)
No computer [Citation Needed] can run an ''actual'' infinite grid, but with some intelligent bounding you can mitigate early signs of problems by maintaining "bubbles" of cells with offsets. You get into problems once you start machine-gunning out gliders (offsets will eventually overflow or awkwardly lose precision, depending on the var-types used; and maintaining a longer and longer bubble, or more and more bubbles just above glider-sized, is probably your other challenge) but it's probably good enough for most purposes. If you somehow have finite patterns that move out in huge (wasteless) cycles from the 'origin' and hold that path until enacting hugely-delayed doglegs (mathematically, it must be a point no further away than can be reasonably enumerated by the bits of information contained within each formation, and significantly less as it'd be a far less efficient count-down cycler than any folded LFSR, but it's ''imaginable'') to meet again at some arbitrary (though deterministic and replicable) distance out in the far far reaches of your abstracted bubble-land then it's possible you could ''pretend'' you have infinite space. [[Special:Contributions/162.158.91.101|162.158.91.101]] 22:26, 13 April 2020 (UTC)
[[User:ProphetZarquon|ProphetZarquon]], do you have a source for your claim that the main point of Conway's creation of Life was to study the edge effects? [https://conwaylife.com/wiki/Conway%27s_Game_of_Life The page for Life on its own wiki] describes the Life grid as "infinite" and only mentions edge effects as inaccuracies to be avoided, and [https://www.youtube.com/watch?v=R9Plq-D1gEk this Conway interview about Life's creation] doesn't mention edges at all.
[[Special:Contributions/108.162.241.24|108.162.241.24]] 23:34, 13 April 2020‎ (UTC)
:First of all, as a tip, reply directly to the comment when you want to talk with someone. Secondly, yeah, I'm pretty sure that person's just blasting ass ham. [[Special:Contributions/172.69.69.28|172.69.69.28]] 02:49, 14 April 2020 (UTC)

Possibly worth noting is the bit of artistry in the rendering. Munroe alters the step period of the iterations so that the deconstruction of the humanoid shape happens more quickly, with the stepping of the glider translating away occurring more slowly. [[User:Fixer|Fixer]] ([[User talk:Fixer|talk]]) 21:52, 13 April 2020 (UTC)

I like the comic very much, and I'm afraid to say I hadn't heard of his death in amongst... well, everything else. RIP.
While I'm here, though, I'm a bit concerned about the current cell generation cycle explanation, as it feels awkward. Currently it is (paraphrased) "live cells survive if just enough neighbours / dead cells come to life with exactly enough neighbours / any other dies or stays dead". I'd prefer something that more delineates it as birth (dead to live, by propogation from the right number of live neighbours), death (live to dead due to ''either'' isolation ''or'' overcrowding) and continuation of state in all other cases. Can't work out a good phrasing yet, but ''may'' try it out later. [[Special:Contributions/162.158.91.101|162.158.91.101]] 22:26, 13 April 2020 (UTC)
: Agreed 100%. I believe the problem lies in the confusion between "cell as in biology" versus "cell as in jail". It would be better to avoid the word "cell" and describe a grid with squares that are either inhabited or empty; inhabitants with two or three neighbours survive to the next generation, otherwise they die (square becomes empty the next generation); exactly three neighbours to an empty square will give birth (become inhabited) in the next generation; and any other empty square stays empty.

Given the cause of death, should this comic be listed among the Covid-19 series? [[User:Momerath|Momerath]] ([[User talk:Momerath|talk]]) 05:02, 14 April 2020 (UTC)
:Yes.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 10:51, 14 April 2020 (UTC)
:No. This is about John Conway. It would have presumably run regardless of the cause of death.

Interesting to see if the next comic is also a Covid-19 comic, because then it will be the 19th covid-19 comic... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 10:53, 14 April 2020 (UTC)

I really think this should not be regarded as a Covid-19 comic, since it's a memorial one and the cause of death is not important for this comic. [[Special:Contributions/162.158.93.105|162.158.93.105]] 14:18, 14 April 2020 (UTC)
:Agree with the others, this is a memorial comic, NOT a COVID-19 comic. I feel like too many comics are being forced into the COVID-19 theme, when they have little to no relation. [[Special:Contributions/172.69.22.62|172.69.22.62]] 16:12, 14 April 2020 (UTC)
::Covid-19 is obviously not directly the topic of the comic, but it is related quite close. So I vote to re-add it to the category, but to put the mention of the connection with the other comics not into the explanation, or on its bottom. If this is acceptable, [[961: Eternal Flame]] should also be included to [[:Category:Cancer]]. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 10:43, 15 April 2020 (UTC)
:::Of course this is one in the Covid series. Randall very rarely makes tributes and it has been 5 year since the last. Conway is not very famous, and had he died a year ago, chances are Randall would not have made this comic. But because he died of Covid while all Randall's comics is about Covid he makes a tribute now. For the same reason I do not think that Eternal flame has anything with the cancer category. Because this was a tribute Randall made without any connection to a series of cancer comics. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 11:25, 15 April 2020 (UTC)
::::Thanks for correcting my spelling errors :D all of that is speculation. How do you know, that Randall is not a huge Conway fan? seems to play exactly into his geekynes. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 12:47, 15 April 2020 (UTC)
:::::I also disagree that Randall is not a huge Conway fan. I believe he would be familiar and interested in the Game of Life automata, as a nerd/geek. It was previously mentioned over 10 years ago in [[696: Strip Games]]. I agree with Lupo's suggestions for this comic. [[Special:Contributions/172.69.34.44|172.69.34.44]] 17:01, 15 April 2020 (UTC)

== Is this original? ==

It would seem remarkable if Randall was able to create this starting pattern at such short notice. If it's copied from somewhere, we should provide that detail. [[User:Stevage|Stevage]] ([[User talk:Stevage|talk]]) 03:54, 15 April 2020 (UTC)
:I do not know if it is taken from another place or a common/known pattern (the comments above seem to suggest otherwise), but it is not uncommon to have an obituary / memorial in stock for elderly persons of relevance. So it might be possible, that e.g. Randall played around with putting stick figures into a simulation, and accidently found this, deciding to keep it somewehere in his archive for this occasion. The seperation of the decaying body and the everlasting part going upward is actually obvious enough to connect with the idea to use it for this occasion. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 10:36, 15 April 2020 (UTC)

== First popularized? ==

The game's popularization "to the general public" in Windows 3.1 really depends on your definition of popular - how many members of the general public had PCs then? I mention this to point out that it was really Martin Gardner's article in SciAm in October 1970 that showed the game to a pretty wide public, although admittedly few people were in a position to program it at the time. As I maintained the University of Cambridge's version on the PDP-7 (then their only computer with a graphics display) in 1971-72 I'm still astonished at how early this publication was. Gardner then did the same for the Mandelbrot Set (which originated in the Other Cambridge...) [[Special:Contributions/162.158.78.74|162.158.78.74]] 04:23, 16 April 2020 (UTC)

== Leaving the grid ==
<blockquote>"However, any given Game of Life is on a finite grid, so once the glider leaves the grid, it has ceased to exist."</blockquote>

Maybe a philosophical nitpick, but I'd like to dispute this. I submit that it is not possible for anything to "leave the grid". A glider can certainly hit the boundary of a bounded grid, but at that point boundary conditions disrupt the pattern and it ''ceases to be a glider''; thus, gliders cannot leave the grid.

Additionally, the grid can be finite and yet still have no boundary; it is quite common for Life grids to wrap one side of the screen to the other. On such a grid, the glider would in fact persist indefinitely. [[User:Hawthorn|Hawthorn]] ([[User talk:Hawthorn|talk]]) 09:18, 16 April 2020 (UTC)
:Also we don't know if the grid maybe is larger than the screen shown in the comic. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 11:36, 16 April 2020 (UTC)

== Triple whammy ==
FYI: Richard Guy, who found the glider first, and is coauthor of Winning Ways with Conway, already died this March. In the biblical age of 103, so possibly nobody even bothered to check for the cause. (The third author, Elwyn Berlekamp, died a year ago.) [[Special:Contributions/141.101.77.32|141.101.77.32]] 18:02, 16 April 2020 (UTC)

== Conway was not a fan of his fame for Life ==

" He’d like to remembered for any of his accomplishments except the Game of Life. He once said he checked the index of every book and if it listed the Game of Life he would refuse to read it." -- https://twitter.com/standupmaths/status/1249105201992171522 [[Special:Contributions/172.69.22.146|172.69.22.146]] 00:04, 17 April 2020 (UTC)

== Conway died on a Doomsday ==

The thing I remember Conway for (in addition to Game of Life) is discovering the Doomsday rule/algorithm for determining days of the week (see https://en.wikipedia.org/wiki/Doomsday_rule). Of course, I'm nowhere near anywhere as fast as he is (I'm happy if I can do it without making a mistake in 10 seconds, more if I'm calculating under the influence). I find it fitting that Conway died on a Doomsday (Saturday for 2020).[[User:Tovodeverett|Tovodeverett]] ([[User talk:Tovodeverett|talk]]) 05:41, 17 April 2020 (UTC)
:Trivia: I was introduced to Conway's Game of Life through the book "The Magic of Lewis Carroll", by John Fischer (1973). One of the Life patterns was the "Cheshire Cat", which was a cat-like face that became a smile, then a paw-print (2x2 stable block). Conway developed the Doomsday algorithm from Lewis Carroll's initial formula, primarily by noting the even month pattern (4/4, 6/6, 8/8, 10/10, 12/12) and the 9 to 5 at 7-11 mnemonic.[[Special:Contributions/172.69.63.191|172.69.63.191]] 13:17, 17 April 2020 (UTC)
:Trivia: More trivia - April 11, 2020 was 42 days after Feb 29, 2020.[[User:Tovodeverett|Tovodeverett]] ([[User talk:Tovodeverett|talk]]) 04:39, 18 April 2020 (UTC)

Talk:2254: JPEG2000

2020-01-14T01:48:15Z

Yosei: jpeg2000 is widely used on archive.org

Cubeball's keyboard has disappeared in the third panel. 22:24, 13 January 2020 (UTC)

Pretty sure the woman in this comic should be called Hairbun. Updating transcript... [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 01:31, 14 January 2020 (UTC)

Jpeg2000 is widely used on archive.org (scans are stored as .jp2 there). For example, the image of this page [https://archive.org/stream/in.ernet.dli.2015.215730/2015.215730.The-Theory#page/n99/mode/1up] is internally from a jp2.zip file:
https://ia601604.us.archive.org/BookReader/BookReaderImages.php?zip=/16/items/in.ernet.dli.2015.215730/2015.215730.The-Theory_jp2.zip&file=2015.215730.The-Theory_jp2/2015.215730.The-Theory_0099.jp2
where BookReaderImages.php seems to be able to read .jp2 in zip and send it to you as a legacy format your browser can handle. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 01:48, 14 January 2020 (UTC)

Talk:2248: New Year's Eve

2020-01-02T09:20:26Z

Yosei: /* Off-by-One Party Theme */

What about people born on New Year's [[User:HelloWorld|HelloWorld]] ([[User talk:HelloWorld|talk]]) 16:28, 30 December 2019 (UTC)

:This method works for them too. For instance, someone born 1/1/2000 will still be 19 on 12/31/2019 (2019 - 2000 = 19) but turn 20 the following day. Why do you think there's a problem for them? [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 16:47, 30 December 2019 (UTC)

::For people born late at night on New Year's Eve it could still present an issue ''theoretically'', but it would at least be the day of their birthday so you're not getting their age wrong so much as observing their birthday!
::[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 18:31, 30 December 2019 (UTC)
:::I believe what you're suggesting is that someone is not one year older until the exact time of their birth on the date of their birth. I don't think anyone gets that pedantic about their age unless they're really vain! ;-) [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 18:45, 30 December 2019 (UTC)

Think we should mention Randall's past "terrible party themes"? The not-that-fun malaria party and the one to celebrate arsenic-based life spring to mind.
[[User:Enfield|Enfield]] ([[User talk:Enfield|talk]]) 21:13, 30 December 2019 (UTC)

Since some readers will not know what "off by one errors" are, that should probably be explained. [[User:MAP|MAP]] ([[User talk:MAP|talk]]) 14:19, 31 December 2019 (UTC)

To all you xkcd fans: HAPPY NEAR YOU!![[Special:Contributions/162.158.214.148|162.158.214.148]] 13:15, 1 January 2020 (UTC)

== Off-by-One Party Theme ==
Anyone have any good tips for an "Off-By-One" party? My birthday is this January & I'm thinking that's as good a theme as any. Of course the invites will feature a "2 guests ±1" RSVP option, but I haven't thought much beyond that yet. Ideas?
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 18:31, 30 December 2019 (UTC)
:This partly depends on whether it's up to the host or the guests to honor the theme of the party. You've given an example for guests. As the host, you could hold the party the day before or after your birthday, all food could be purchased as baker's dozens (13 items instead of 12), the age on the cake could be off by one, or you could hold the party at your neighbor's house with their agreement (address of house off by one?). [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 18:55, 30 December 2019 (UTC)
: Time: You could leave the start/end time flexible (+/- 1) . Or give the incorrect start time. Maybe go with the pun "everyone must be off (leave the party) by one" (am/pm) depending on the party. [[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 19:42, 30 December 2019 (UTC)
: Decor: you could remove a light bulb from each fixture/room. Be short by one for glasses, plates, chairs, etc. Maybe each time a guests as for "a slice/serving/whatever" they get none or 2. (Roll for it? And encourage sharing?) An extra cake with a different number of candles. [[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 19:42, 30 December 2019 (UTC)

:possible "off-by-1" themed decorations for a party of programmers:
:* Write a message that reads: “The last one of the 4 boxes is obviously box 4.” Below the message, draw four boxes, and write 0-indexed numbers on them as 0, 1, 2, 3.
:*Get 6 party balloons or similar colorful items, write P, A, R, T, Y cheerfully on the first 5 of them, one letter on each. On the last one, write with smaller letters, darkly: “Not null-terminated (not allocated)” If desired add a cartoon character *p++ running left-to-right happily in the cheerful section, not knowing what is going to happen. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 03:42, 31 December 2019 (UTC)

:Games or activities:
:* Musical chairs (given there is always one fewer chair than people) [[User:Bermudadad|Bermudadad]] ([[User talk:Bermudadad|talk]]) 17:11, 31 December 2019 (UTC)

:Off-by-one parties tend to suffer from buffet overflows. (It also strikes me that invitations for ''1 guest ±1'' are actually the standard, even if not phrased that way.) [https://iamkate.com/ Kate Rose Morley] 19:35, 31 December 2019 (UTC)

How about having a "Ring in the New Decade" party on 1 Jan 2020 instead of when it happens on 1 Jan 2021? [[Special:Contributions/162.158.214.136|162.158.214.136]] 13:26, 1 January 2020 (UTC)

When you were born, it was obviously your birthday. How old are you at a 21st birthday party? [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 09:20, 2 January 2020 (UTC)

== Specific calculations ==

So, how old's Jesus? Two-thousand and nineteen? Two-thousand and eighteen? Two-thousand and twenty-(three...seven)? Well into this decade, some churches round here ''still'' had the ubiquitous cross-denominational "It is Christ's 2000th birthday!" plaques up from the false-millenium (I might have a look now to see if any still do!) but of all the things they get wrong I don't think that's particularly the biggest thing, so... ;) [[Special:Contributions/162.158.154.91|162.158.154.91]] 18:49, 30 December 2019 (UTC)

I'm going to remove the second paragraph about it not working for New Year's Day, as Cueball explicitly states that New Year's Eve is the ONE day of the year when it works. The extra paragraph is just confusing at a minimum. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 19:37, 30 December 2019 (UTC)

Talk:2248: New Year's Eve

2019-12-31T03:42:44Z

Yosei: /* Off-by-One Party Theme */

What about people born on New Year's [[User:HelloWorld|HelloWorld]] ([[User talk:HelloWorld|talk]]) 16:28, 30 December 2019 (UTC)

:This method works for them too. For instance, someone born 1/1/2000 will still be 19 on 12/31/2019 (2019 - 2000 = 19) but turn 20 the following day. Why do you think there's a problem for them? [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 16:47, 30 December 2019 (UTC)

::For people born late at night on New Year's Eve it could still present an issue ''theoretically'', but it would at least be the day of their birthday so you're not getting their age wrong so much as observing their birthday!
::[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 18:31, 30 December 2019 (UTC)
:::I believe what you're suggesting is that someone is not one year older until the exact time of their birth on the date of their birth. I don't think anyone gets that pedantic about their age unless they're really vain! ;-) [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 18:45, 30 December 2019 (UTC)

Think we should mention Randall's past "terrible party themes"? The not-that-fun malaria party and the one to celebrate arsenic-based life spring to mind.
[[User:Enfield|Enfield]] ([[User talk:Enfield|talk]]) 21:13, 30 December 2019 (UTC)

== Off-by-One Party Theme ==
Anyone have any good tips for an "Off-By-One" party? My birthday is this January & I'm thinking that's as good a theme as any. Of course the invites will feature a "2 guests ±1" RSVP option, but I haven't thought much beyond that yet. Ideas?
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 18:31, 30 December 2019 (UTC)
:This partly depends on whether it's up to the host or the guests to honor the theme of the party. You've given an example for guests. As the host, you could hold the party the day before or after your birthday, all food could be purchased as baker's dozens (13 items instead of 12), the age on the cake could be off by one, or you could hold the party at your neighbor's house with their agreement (address of house off by one?). [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 18:55, 30 December 2019 (UTC)
: Time: You could leave the start/end time flexible (+/- 1) . Or give the incorrect start time. Maybe go with the pun "everyone must be off (leave the party) by one" (am/pm) depending on the party. [[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 19:42, 30 December 2019 (UTC)
: Decor: you could remove a light bulb from each fixture/room. Be short by one for glasses, plates, chairs, etc. Maybe each time a guests as for "a slice/serving/whatever" they get none or 2. (Roll for it? And encourage sharing?) An extra cake with a different number of candles. [[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 19:42, 30 December 2019 (UTC)

:possible "off-by-1" themed decorations for a party of programmers:
:* Write a message that reads: “The last one of the 4 boxes is obviously box 4.” Below the message, draw four boxes, and write 0-indexed numbers on them as 0, 1, 2, 3.
:*Get 6 party balloons or similar colorful items, write P, A, R, T, Y cheerfully on the first 5 of them, one letter on each. On the last one, write with smaller letters, darkly: “Not null-terminated (not allocated)” If desired add a cartoon character *p++ running left-to-right happily in the cheerful section, not knowing what is going to happen. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 03:42, 31 December 2019 (UTC)

== Specific calculations ==

So, how old's Jesus? Two-thousand and nineteen? Two-thousand and eighteen? Two-thousand and twenty-(three...seven)? Well into this decade, some churches round here ''still'' had the ubiquitous cross-denominational "It is Christ's 2000th birthday!" plaques up from the false-millenium (I might have a look now to see if any still do!) but of all the things they get wrong I don't think that's particularly the biggest thing, so... ;) [[Special:Contributions/162.158.154.91|162.158.154.91]] 18:49, 30 December 2019 (UTC)

I'm going to remove the second paragraph about it not working for New Year's Day, as Cueball explicitly states that New Year's Eve is the ONE day of the year when it works. The extra paragraph is just confusing at a minimum. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 19:37, 30 December 2019 (UTC)

Talk:2241: Brussels Sprouts Mandela Effect

2019-12-14T04:24:42Z

Yosei: the silica gel joke may be actually a keen observation

Brussels Sprouts Mandella Effect dot Tumblr dot com--[[User:GoldNinja|GoldNinja]] ([[User talk:GoldNinja|talk]]) 00:20, 14 December 2019 (UTC)

Is liquorice ''really'' so disliked as suggested? For me it's "Meh" ({{w|Liquorice allsorts}} are all the better for being partnered with sweetness in various ways), but pallatable enough in its plain form. Although I admit the versions salted with ammonium chloride are a more acquired taste to my (apparently) non-European tastebuds. I won't eat those in handfulls, just the odd occasionally grabbed morsel from the bag that gets rapidly emptied by the continental person who brought them... [[Special:Contributions/141.101.98.250|141.101.98.250]] 00:25, 14 December 2019 (UTC)

Silica packets are harmless to eat:

https://www.mentalfloss.com/article/19775/what-would-happen-if-you-ate-one-those-silica-gel-packets

The joke (a supposedly false statement) about silica gel may be actually a true, keen observation: people are “misled” to believe that it is absolutely NOT edible (i.e. poisonous) because of the strong warning DO NOT EAT they read again and again (see e.g. [https://biology.stackexchange.com/questions/21181/what-would-happen-if-one-eats-silica-gel]). Maybe this ''is'' intended; maybe it's just a joke (lie) that turned out to be true. What do you think?
[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 04:24, 14 December 2019 (UTC)

Talk:2237: AI Hiring Algorithm

2019-12-04T22:20:02Z

Yosei: the origin of 'deep'

Not sure this has to do with deepmind. Deep is a term used generally for recurrent neural networks.
[[Special:Contributions/172.68.34.82|172.68.34.82]] 19:34, 4 December 2019 (UTC)

:Agree. Maybe we should just mention that? [[Special:Contributions/172.68.141.136|172.68.141.136]] 20:10, 4 December 2019 (UTC)
:The origin of ''deep'' seems to be [https://en.wikipedia.org/wiki/List_of_minor_The_Hitchhiker%27s_Guide_to_the_Galaxy_characters#Deep_Thought Deep Thought] via [https://en.wikipedia.org/wiki/Deep_Blue_(chess_computer) Deep Blue]. [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 22:20, 4 December 2019 (UTC)
I don't like how "our" font for the comic title made me think it said "Al Hiring Algorithm" (although now I do want to see that comic!) (the actual xkcd website's comic title is in large/small caps, so it is unambiguous.) [[User:Mathmannix|Mathmannix]] ([[User talk:Mathmannix|talk]]) 20:17, 4 December 2019 (UTC)

I first heard about this type of system existing a few weeks ago. https://www.technologyreview.com/f/614694/hirevue-ai-automated-hiring-discrimination-ftc-epic-bias/ [[Special:Contributions/172.68.65.66|172.68.65.66]] 20:37, 4 December 2019 (UTC)

That's a big problem with AI as it's currently handled -- the AI's have to be trained, and the training is usually by feeding them lots of existing information, which means widespread errors and patterns of discrimination are inevitably going to color the AI's decisions, leading to feedback loops that favor existing discrimination. If feeding tons of books or case records or whatever to an AI, where say 95% of them were historically written by white males, one can expect an AI viewpoint that would lean towards what white men think. Garbage in, garbage out... amplified. [[User:N0lqu|-boB]] ([[User talk:N0lqu|talk]]) 21:29, 4 December 2019 (UTC)

So it's a slightly less stupid version of [https://rationalwiki.org/wiki/Roko's_basilisk Roko's basilisk]? -- [[User:Wasell|Wasell]] ([[User talk:Wasell|talk]]) 21:27, 4 December 2019 (UTC)

Talk:2214: Chemistry Nobel

2019-12-02T12:41:10Z

Yosei:

No Discussion yet? REALLY?!!? [[Special:Contributions/162.158.214.82|162.158.214.82]] 15:23, 12 October 2019 (UTC)

This may be a reference to SCP-2046. [[Special:Contributions/162.158.146.34|162.158.146.34]] 15:40, 12 October 2019 (UTC)
:Or something else. From the beginning, what are the ten radical isotopes? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 21:36, 12 October 2019 (UTC)

Couldn't this potentially involve exotic isotopes of hydrogen that behave similarly to elements in the same group? --[[Special:Contributions/162.158.214.136|162.158.214.136]] 16:02, 12 October 2019 (UTC)

Oh gods, I needed this laugh. Have my Chemistry exam on Monday, this does put a smile on my face.

''"misconception that the empty space at the top of the periodic table represents undiscovered elements"''... [citation needed]. Is that really a thing? Never heard of it. [[User:Ralfoide|Ralfoide]] ([[User talk:Ralfoide|talk]]) 16:53, 12 October 2019 (UTC)
:Somehow I did not think about that the entire time I was editing this thing, because I don’t believe it is. I guess I’ll fix it. [[Special:Contributions/172.69.34.56|172.69.34.56]] 18:32, 12 October 2019 (UTC)
::I guess my point, if I had any, is that I have a hard time believing there's such a "misconception" to begin with in real life. Of course, there is in Randall's strip universe, which is what makes the joke work in his usual out-of-this-world humor. [[User:Ralfoide|Ralfoide]] ([[User talk:Ralfoide|talk]]) 07:40, 13 October 2019 (UTC)

Some uninvited pedantry (unlike all my other didactic discourse here, which you guys bring on yourselves): Referenced in the comic is not THE periodic table, just ''a'' periodic table. And it isn't really objectively scientific. It's better to call it the ''most popular'' periodic table. Such tables are a rather ham-handed attempt to explain the patterns of the elements in an "intuitive" (or at least heuristic) way. But the popular one we learn in school is actually far from the best one even in that sense. [[wikipedia:Alternative periodic tables|Check out the alternatives]], many of which are more scientifically sound and logical...but aren't as simplistic for the easy-minded, so they haven't caught on. —[[User:Kazvorpal|Kazvorpal]] ([[User talk:Kazvorpal|talk]]) 23:37, 12 October 2019 (UTC)
:Do you mean the one that looks like a candyland board game (Benfey's) or the one that looks like the worst Tetris level ever (Tsimmerman's)? [j/k]... If I had seen that in school, I'd have been too distracted to ever pay attention ;-) [[User:Ralfoide|Ralfoide]] ([[User talk:Ralfoide|talk]]) 07:35, 13 October 2019 (UTC)
:A very interesting link. Thanks! [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 12:41, 2 December 2019 (UTC)

Did Mendeleev really design his table to represent the way electrons are arranged in atoms? In 1869, he must have been quite a visionary! Zetfr 09:23, 13 October 2019 (UTC)
:Oh no, he didn't. He did by patterns of their properties. Also by atomic weights, but those were imprecisely known then, also note the isotope paradox problem (e.g. K and Ar must be swapped). The first sorting already guarantess to represent the electronic arrangement to some degree. BTW, lanthanides and actinides need more love. For starters, I PhD'ed on them.
::Actually he was quite the visionary, considering what they didn't know back then. While everybody else was arranging their tables (and there were plenty of them) entirely by atomic weight, he arranged them by both atomic weight on the large scale and chemical valence on the small scale. This clued him in to the changing periods and also enabled him to correct elements out of order by weight. The noble gases hadn't been discovered yet, but when they were, they fit right in as they had a valence of zero. A few decades later [[wikipedia:Henry Mosely|Henry Mosely]] used proton bombardment and X-Ray radiation measurement to determine the electrostatic properties of various elements and found a simple progression that both absolutely vindicated Mendeleev and introduced the concept of [[wikipedia:Atomic Number|Atomic Number]]. He should have gotten a Nobel prize, but sadly, no prizes were awarded that year because of the war and Mosely himself was killed at the young age of 27 by a bullet with his name on it. Sigh.
[[Special:Contributions/172.69.55.22|172.69.55.22]] 15:20, 13 October 2019 (UTC)

Clearly these new elements are fractional elements, with elements having - for instance - 1 3/16 protons, etc. [[Special:Contributions/108.162.241.248|108.162.241.248]] 21:20, 13 October 2019 (UTC)

Of course, if someone ''did'' find a whole bunch of elements there, I'd say that they ''deserve'' a Nobel prize. [[Special:Contributions/172.69.63.133|172.69.63.133]] 12:37, 14 October 2019 (UTC)

for me, the explanation provided doesn't seem to emphasize why the joke works well enough. shouldn't the explanation more clearly state that the gap between hydrogen and helium is there because the table is grouped based on blocks of elements and electron orbits. the first row only has electrons in the s orbital and none in p, d or f orbitals, and that gaps between hydrogen and helium, for example, could not possibly be filled because there isn’t anything to fill them with. similarly for the 2nd and 3rd row "gaps". this impossibility really begets the humor of a figure pointing at the gap musing "i don't know why no one else thought to look here".

Talk:2168: Reading in the Original

2019-07-06T01:52:51Z

Yosei: Random thoughts / clarification about Greek

I removed this line from the explanation: "The New Testament is often studied in the 'original' Greek, despite most of the protagonists actually speaking Aramaic." Reason: While the "protagonists" likely spoke Aramaic, the actual written text was in Koine Greek. The spoken language is a red herring in this case. [[Special:Contributions/162.158.126.118|162.158.126.118]] 14:34, 26 June 2019 (UTC)
:It could be relevant for sections which are basically writing down something said (in Aramaic). -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:36, 26 June 2019 (UTC)
::Even if the people being quoted would have been speaking Aramaic, the Aramaic words they would have said may have never been written down, only a translation of it into a form of Greek (presuming the conversation in question ever actually occurred and wasn't invented by a later writer.) However, doing a quick search, I found claimed that 268 verses were originally written in Aramaic (parts of Daniel, Erza, and one verse of Jeremaih, along with a few other scattered words and names). This is out of a total 23,145 Old Testament verses. Most scholars believe the original version of all the New Testament was a form of Greek (though notably somewhat different than what is normally known as "ancient Greek.")--[[Special:Contributions/172.68.38.94|172.68.38.94]] 05:19, 29 June 2019 (UTC)

There's also a [https://la.wikipedia.org/wiki/Vicipaedia:Pagina_prima Latin Wikipedia] and an [https://ang.wikipedia.org/wiki/H%C4%93afodtramet Old English Wikipedia]. [[User:KangaroOS|Kangaro]][[User talk:KangaroOS|OS]] 14:53, 26 June 2019 (UTC)
:There would have been an Ancient Greek Wikipedia too if not for Yaroslav Zolotaryov and Siberian - [https://meta.wikimedia.org/wiki/Requests_for_new_languages/Wikipedia_Ancient_Greek_2 the proposal] was effectively accepted, and only a little bit short of fulfillment, when the Siberian debacle had Wikimedia revise their acceptance system in October 2007. Alas, despite several re-proposals, there is no Ancient Greek Wikipedia to this day, and realistically there would probably only be one if someone raises a child as an Ancient Greek native speaker. (This had happened with Coptic.) [[Special:Contributions/162.158.182.148|162.158.182.148]] 15:47, 26 June 2019 (UTC)

Btw there's no Greek Wikipedia page for Xkcd :) [[Special:Contributions/172.68.51.166|172.68.51.166]] 14:58, 26 June 2019 (UTC)
:Well, it would rather be for χκcδ [[Special:Contributions/198.41.230.112|198.41.230.112]] 15:44, 26 June 2019 (UTC)
::Rather ξκcδ/ξκσδ as xi (not chi) is equivalent to 'x'. The lunate sigma is rather uncommon. Of course I think if we're talking about ancient Greek there were no lowercase letters so it'd be ΞΚΣΔ. [[Special:Contributions/172.68.189.175|172.68.189.175]] 16:08, 26 June 2019 (UTC)
:::Am I the only one who read ΞΚΣΔ as being startlingly close (visually) to IKEA?[[Special:Contributions/162.158.126.22|162.158.126.22]] 16:32, 26 June 2019 (UTC)
:::: Nah, first thing I noticed. :) [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 04:27, 28 June 2019 (UTC)
::: Nope. Thought the same thing and suddenly wondered if the xkcd name origin story has finally been proven to be a hoax. Have we all been had?[[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 19:31, 26 June 2019 (UTC)

Hello, everyone! I have been consulting this wiki for a lot of time now, but this is the first time I edit. I edited the 'the New Testament of the Bible being the most notable' sentence because the New Testament is hardly the only notable work in Ancient Greek. In fact, while I'm not familiar with the situation in the U.S., in schools in the EU where I've studied or my mother (who went to Catholic school) has studied, texts from the New Testament were not even taught. Part of the reason for this is that the New Testament uses Koine Greek, which is a later variant of what is commonly called "Ancient Greek". I also think it's worth mentioning that Ancient Greek is quite commonly studied in many European countries even by high-school students, not only by dedicated scholars. [[User:AleksanderV|AleksanderV]] ([[User talk:AleksanderV|talk]]) 18:45, 26 June 2019 (UTC)

Made a small correction by removing Socrates from the list of people who wrote in Greek, since Socrates did not in fact write anything! (or, at least, no original works from Socrates survive, even though some of his followers wrote dialogues with Socrates as a character) ~High Falutin Scholar

Man, you guys '''all got the joke wrong'''! The ARTICLE isn't in Greek, it's Wikipedia's MENUS and screen ELEMENTS that are in Greek! The article itself is still in English, but you're reading it in a Greek "environment". I added a paragraph to clear that up, while leaving the good wrong stuff still there, since it's not wrong in the right context. [[User:N0lqu|-boB]] ([[User talk:N0lqu|talk]]) 19:44, 28 June 2019 (UTC)
:No, that seems wrong. In the sidebar is the link to the Wikipedia in Greek, it's even more difficult to find the Greek language settings for the menus and such. Also the reference in the title text to the articles being shorter only makes sense of it's a different language version.--[[Special:Contributions/162.158.93.93|162.158.93.93]] 22:43, 28 June 2019 (UTC)
::Yeah, clicking the option in the lower left does change the language of the articles, not just the menu and screen elements. After all otherwise the title text wouldn't make sense, as it is referencing how the amount of content in Wikipedia is much lower in most languages other than English, especially languages with relatively few speakers (there are much fewer people who speak Greek than English worldwide), resulting in both shorter articles and fewer total articles, so many English articles wouldn't have a Greek version at all. In any case, the paragraph you added should be removed.--[[Special:Contributions/172.68.38.94|172.68.38.94]] 05:19, 29 June 2019 (UTC)
:As others have said, you are incorrect and I've removed your changes. You can try the procedure Cueball recommended yourself - it links you to the actual Greek Wikipedia rather than just changing the interface. Furthermore, the alt-text backs this up, since the joke about articles being shorter only makes sense if Cueball is viewing the actual Greek Wikipedia (articles there are shorter due to it being newer and having fewer editors. Obviously they would be the same length if he was only changing the interface.) The joke is that that should have cued him in to the fact that the Greek language was not the original, but instead he invented another ridiculous explanation for it. --[[User:Aquillion|Aquillion]] ([[User talk:Aquillion|talk]]) 23:35, 29 June 2019 (UTC)
:When I did it exactly like the comic said, it changed the screen elements to Greek, but left me on the English wikipedia (en.wikipedia.org), so maybe there are different modes for changing. But I concede the point about the articles being shorter pointing to the original explanation being the correct one. [[User:N0lqu|-boB]] ([[User talk:N0lqu|talk]]) 17:46, 1 July 2019 (UTC)

I feel very stupid, but could someone explain the reason why Greek is considered to be the "original language"? Greek is not the origin of all the languages in Wikipedia, it's not even the origin of English. Ancient Greece is the origin of much of the western culture, but much of it is still older or coming from differnt parts of the world. Or am I totally on the wrong leg here, and is it just a play on the word Wikipedia? Anyway, the choice of Greek as the original language in this comic could use some explaining. --[[User:Pbb|Pbb]] ([[User talk:Pbb|talk]]) 18:39, 30 June 2019 (UTC)

Just a random comment, but I think there is another important reason why one may wants to read the original Greek version of something. That is, when you’re interested in poems. For anyone who actually reads Greek poems even a little, it is VERY obvious that they are “musical” so to speak (this is NOT a pedantic opinion, it’s quite intuitive, you can feel it): the pitch accents of the language and rhythms of the verses (e.g. hexameter of Homer) automatically create “melodies”, and these melodies go magically well with the meaning of the verses — e.g. a furious melody when the phrase is furious, a light-hearted melody when the phrase is light-hearted, and so on. The effect (music-meaning combination) is so overwhelming and fascinating that probably it is untranslatable.

As for the New Testament, I agree that it’s not a good example here, which might cause unnecessary religious wars too, when this xkcd piece is not related to religions at all. That said, just fyi, there are quite a few places where you understand the Greek NT better if you know Aramaic. E.g. “wind” and “spirit” are the same word in Aramaic; knowing that, John 20:22, Acts 2:2-4, etc. suddenly make sense. Also some phrases of the Greek NT are actually written in Aramaic: e.g. in Mark 5:14 Jesus says, in Aramaic, ܛܠܝܬܐ ܩܘܡܝ
which might sound mystic, but actually it’s just a normal, daily sentence that simply means “Girl, stand up!”
Also in 1Cor 16:22, they say “Our lord, come!” in Aramaic. (I’m not a religious person, just studying Syriac as a hobby. Sorry if this is boring for you.) Incidentally, the word “Holy Spirit” is feminine in Aramaic. When Jesus or John talked about it, they meant “she”. This piece of trivia might interest you.

PS: Another commentator said that Koine and the “normal” Greek (Attic) were different; which is true, but they are not so different. Usually one can use the same Greek-English dictionary when they read whichever (Attic, Koine, and also Homeric Greek). — [[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 01:52, 6 July 2019 (UTC)

Talk:1047: Approximations

2019-02-17T08:19:44Z

Yosei: Yet another proof of cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2

The US population estimate is now off by 7 million, although 2018 just started. Even so, in December 2017, it would have been 4 million off. [[User:625571b7-aa66-4f98-ac5c-92464cfb4ed8|625571b7-aa66-4f98-ac5c-92464cfb4ed8]] ([[User talk:625571b7-aa66-4f98-ac5c-92464cfb4ed8|talk]]) 00:54, 19 January 2018 (UTC)

: Off by 7 million out of 7-8 billion means that it's accurate to one part in 1,000. That's consistent with it's location in the chart -- next to other values that are accurate to 1 in 1,000. {{unsigned|Redbelly98}}

The world population estimate is still accurate to within .1 billion. [[Special:Contributions/162.158.63.28|162.158.63.28]] 13:41, 5 May 2017 (UTC)

They're actually quite accurate. I've used these in calculations, and they seem to give close enough answers. '''[[User:Davidy22|Davidy22]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 14:03, 8 January 2013 (UTC)

I only see a use for the liters in a gallon one. The rest are for trolling or simple amusement. The cosine identity bit our math team in the butt at a competition. It was painful. --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 05:27, 17 August 2013 (UTC)

Annoyingly this explanation does not cover 42 properly, it does not say that Douglas Adams got the number 42 from Lewis Carroll, who is more relevant to the page because he was a mathematician named Charles Lutwidge Dodgson. He was obsessed with the number forty-two. The original plate illustrations of Alice in Wonderland drawn by him numbered forty-two. Rule Forty-Two in Alice in Wonderland is "All persons more than a mile high to leave the court", There is also a Code of Honour in the preface of The Hunting of the Snark, an extremely long poem written by him when he was 42 years old, in which rule forty-two is "No one shall speak to the Man at the Helm". The queens in Alice Through the Looking Glass the White Queen announces her age as "one hundred and one, five months and a day", which - if the best possible date is assumed for the action of Through the Looking-Glass - gives a total of 37,044 days. With the further (textually unconfirmed) assumption that both Queens were born on the same day their combined age becomes 74,088 days, which is 42 x 42 x 42. --[[Special:Contributions/139.216.242.254|139.216.242.254]] 02:43, 29 August 2013 (UTC)

:: This explanation covers 42 adequately, and would probably be made slightly worse if such information were added. The very widely known cultural reference is to Adams's interpretation, not Dodgson's original obsession. Adding it would be akin to introducing the MPLM into the explanation for the hijacking of Renaissance artists' names by the TMNT. I definitely concede that it does not cover 42 exhaustively, but I think it can be considered complete and in working order without such an addition. If it really irks you, be bold and add it! --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 00:37, 30 August 2013 (UTC)

"sqrt(2) is not even algebraic in the quotient field of Z[pi]" is not correct. Q is part of the quotient field of Z[pi] and sqrt(2) is algebraic of it. The needed facts are that pi is not algebraic, but the formula implies it is in Q(sqrt(2)). --DrMath 06:47, 7 September 2013 (UTC)

13/15 is a better approximation to sqrt(3)/2 than is e/pi. Continued fraction approximations are great! --DrMath 07:23, 7 September 2013 (UTC)

How could he forget 1 gallon ≈ 0.1337 ft³?! [[Special:Contributions/67.188.195.182|67.188.195.182]] 00:51, 8 September 2013 (UTC)

Worth mentioning that Wolfram Alpha now officially recognizes the [http://www.wolframalpha.com/input/?i=e%5E-%28%281%2B8%5E%281%2F%28e-1%29%29%29%5E%281%2Fpi%29%29 White House switchboard constant] and the [http://www.wolframalpha.com/input/?i=%287%5E%28e-1%2Fe%29-9%29*pi%5E2 Jenny constant]. [[Special:Contributions/86.164.243.91|86.164.243.91]] 18:28, 8 October 2013 (UTC)

Maybe we should add the [Extension:LaTeXSVG LaTeX extension] to make it easier to transcribe these equations. -- [[Special:Contributions/108.162.219.220|108.162.219.220]] 23:02, 16 December 2013 (UTC)

;Protip - Does anyone see the correct equation?
Maybe this is just an other Wolfram Alpha error, like we recently have had here: [[1292: Pi vs. Tau]]. All equations still look invalid to me.
*''√2 = 3/5 + π/(7-π)'': is impossible because √2 is an irrational number and no equation can match.
*''cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2'': could only match if ''cos(x) + cos(3x) + cos(5x) = 1/2'' would be valid, because ''π/7'' is also an irrational number.
*''γ = e/34 + e/5 or γ = e/54 + e/5'': would mean that a sum of two irrational numbers do fit to the Gamma Constant. Impossible.
*''√5 = 13 + 4π / 24 - 4π'': √5 and π are irrational numbers, there is no way to match them in any equation like this.
*''Σ 1/nn = ln(3)e'': doesn't make any sense either.
Maybe [[:Category:Comics featuring Miss Lenhart|Miss Lenhart]] can help.
--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:41, 17 December 2013 (UTC)

cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2 is exactly correct.

Let a=π/7, b=3π/7, and c=5π/7, then
(cosa+cosb+cosc)⋅2sina=2cosasina+2cosbsina+2coscsina=sin2a+sin(b+a)−sin(b−a)+sin(c+a)−sin(c−a)=sin(2π/7)+sin(4π/7)−sin(2π/7)+sin(6π/7)−sin(4π/7)=sin(6π/7)=sin(π/7)=sina

Hence, cos(π/7) + cos(3π/7) + cos(5π/7) = sin(π/7) / 2sin(π/7) = 1/2
[[Special:Contributions/108.162.216.74|108.162.216.74]] 01:57, 16 January 2014 (UTC)

:What is this: sin(6π/7)=sin(π/7) ? A new math is born... --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 20:49, 16 January 2014 (UTC)

::Actually it does. My proof is geometric: the sines of two supplementary angles (angle a + angle b = π (in radians)) are equivalent because they necessarily have the same x height in a Cartesian plane. Look on a unit circle, or even a sine function. Also, Calculus and most other mathematics use radians over degrees because they make the functions simpler and eliminate irrationality when a trig function shows up, but physics uses degrees because it's easier to understand and taught first. Anonymous 01:27, 13 February 2014 (UTC)
::As an aside, just how far along in math are you? Radian measure is taught in high school (at least the good ones). Anonymous 13:24, 13 February 2014 (UTC)
:::Sure, I was wrong at my last statement. sin(6π/7)=sin(π/7) is correct by using the radian measure. But just change π/7 to π/77 would give a very different result on that formular here. I still can't figure out why PI divided by the number 7 should be that unique, PI divided by 77 should be the same. My fault is: I still can't find the Nerd Sniping here. And we all do know that Randall did use wrong WolframAlpha results here. According to the last question: I'm very well on Math, that's because I want to understand this. This is like 0.999=1. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:01, 13 February 2014 (UTC)
::::Ah, I see. I think it has to do with the way e^i*π breaks down, as one of the answers shown in the corresponding link explains, but other answers rely on various angle identities (including the supplementary sines one in the proof above). Anonymous 03:10, 14 February 2014 (UTC) (PS, have you checked [[545]] lately? I answered your question there, too)
:::::As per the derivation from january 16 , you can use any a,b,c that satisfies this set of equations: 2 a = b - a, a + b = c- a, c + a = π - a. This is due to the fact that sin(x) = sin(π-x), and what was derived the 16th. [[Special:Contributions/173.245.53.199|173.245.53.199]] 12:38, 21 February 2014 (UTC)
:::: Dgbrt: If not convinced by the proofs linked to in the "explanation" part, you might want to try this: [http://www.wolframalpha.com/input/?i=sum_%28k%3D0%29%5E38+cos%281%2F77+%282+k%2B1%29+pi%29]. I'm sure you'll find inspiration for similar formulas using PI over [any odd integer]. Your assumption that Randall used WolframAlpha for this very identity is probably wrong. This is a very well-known formula that appears in many high school books, and I am pretty sure it is part of Randall's culture. And this has nothing to do with 1=1. As for your original post,
::::*√2 = (√2-1)/((4-2)π/2-π)+1 : Is this what you call "matching an equation" to √2?
::::*So what you mean is that if an equation is true for an irrational number, then it must be for any real number? Like, (√2)^2 = 2, but because √2 is irrational, then x^2=2 (for all x?)
::::*This one's a bit tough. You will probably agree that γ-√2 is irrational. And so is √2. What about their sum?
::::*Well, maybe it doesn't to you. But is Σ n-2 = π^2/6 any better? Well, this one is true (using Fourier's expansion of the rectangular function).
::::Finally,
::::*√2 = 3/5 + π/(7-π) is false because it would imply that π is an algebraic number
::::*cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2 is true, and proven by many
::::*γ = e/34 + e/5 seems false. But there doesn't seem to be a quick way to disprove.
::::*Σ 1/nn = ln(3)e seems false, but I can't see why. [[Special:Contributions/108.162.210.234|108.162.210.234]] 09:15, 11 May 2014 (UTC)
::Dgbrt, yes, sin(6π/7)=sin(π/7). Simple proof: sin(6π/7)=sin(π-π/7)=sin(π)cos(-π/7)+cos(π)sin(-π/7)=0*cos(-π/7)+(-1)*(-sin(π/7))=0+sin(π/7)=sin(π/7) [[Special:Contributions/108.162.215.89|108.162.215.89]] 02:34, 20 May 2014 (UTC)
;So, still incomplete?

Where's our (in)complete judge? [[Special:Contributions/199.27.128.186|199.27.128.186]] 19:21, 18 December 2013 (UTC)
:The protip is still a mystery. I'm calling for help a few lines above. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:16, 18 December 2013 (UTC)
::The cosine one, in radians, is correct [[Special:Contributions/141.101.88.225|141.101.88.225]] 12:54, 28 April 2014 (UTC)

The 'Seconds in a year' ones remind me of one of my favorite quotes: "How many seconds are there in a year? If I tell you there are 3.155 x 10^7, you won't even try to remember it. On the other hand, who could forget that, to within half a percent, pi seconds is a nanocentury" -- Tom Duff, Bell Labs. [[User:Beolach|Beolach]] ([[User talk:Beolach|talk]]) 19:14, 17 April 2014 (UTC)
:Please do not change former discussions. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 23:57, 17 April 2014 (UTC)

;cos(pi/7) + cos(3pi/7) + cos(5pi/7) = 1/2 ???
Why the hell the divider seven makes the difference?
*cos(pi) + cos(3*pi) + cos(5*pi) = -3
*cos(pi/8) + cos(3*pi/8) + cos(5*pi/8) = 0.92387953251128675612818318939678828682241662586364...
So why the "magic" prime number seven produces this exact result? I know radians and π/7 is just a small part of a circle which is 2π. One prove claims that sin(6π/7) equals to sin(π/7); my best calculator can't show a difference. Of course sin(6π) equals to sin(π), in radians, BUT sin(6π/8) is NOT equal to sin(π/8). So if the number 7 plays a magic rule here this would be "one of the", no... the BIGGEST mystery in mathematics forever. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 23:03, 16 May 2014 (UTC)
:Dgbrt, please see my answer from 11 May 2014 up there. Any odd integer will do, as long as you sum enough of cos(pi/[thing]).
:*Let's try with 5 : cos(pi/5) + cos (3pi/5) = 1/2.
:*With 9 : cos(pi/9)+ cos(3pi/9) + cos (5pi/9) + cos(7pi/9) = 1/2
: No big mystery around here. Just a beautiful formula :) I think there are similar formulas with cosines and even integers. I'll post them here if I have time. [[User:Varal7|Varal7]] ([[User talk:Varal7|talk]]) 09:56, 17 May 2014 (UTC)

::You mixing up to different equations and even not prove them. If there is any prove to a mathematician I would accept and include a proper explain for non math people here. We still have to find a prove. And I do not trust my calculators, we just have to explain why even cos(pi/5) + cos (3pi/5) is also nearly the same. This issue is still not explained. So please give us a explain. And a PROTIP: This does not work with Integers, PI is infinite--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 17:55, 17 May 2014 (UTC)

:::Okay. If I understood what you said.
:::* I mix up different topics. -> True. From now on, we'll just focus on the cosine one.
:::* You ask for a proof/explanation. -> My opinion is those are two different requests. Maybe that's why you use the distinction between math people/not math people. For a proof, please read further. What I exposed above are just other "fun experiments" we could do. e.g : [http://www.wolframalpha.com/input/?i=cos%28pi%2F11%29%2Bcos+%283pi%2F11%29+%2B+cos+%285pi%2F11%29+%2B+cos+%287pi%2F11%29%2Bcos+%289pi%2F11%29].
:::* You do not trust your calculators -> Great. I don't either. (Well more accurately, I trust mine to 10^-8, so I would definitely not use it to prove any of the discussed equations in PROTIP). That's why we'll prove the formulas we assert.
:::* "This does not work with integers" -> Well, I got myself misunderstood. It would probably have been better if I had said: the following formula is true for all integer n. sum_{k=0}^{n-1}{cos((2k+1)*pi/(2n+1)). But It's harder to read, so just say. Choose any odd integer, say N=2n+1. Then start the following sum. cos(pi/N) + cos(3pi/N) + … and stop when the numerator is cos((N-2)pi/N). Then the result is 1/2. And that's what we'll prove, a few lines down from here.
:::*"Pi is infinite" -> That's a common misconception. What you mean is, Pi is irrational. (Fun fact: Pi is a transcendental number. Quite difficult theorem. Lindeman proved it in 1882. Hence, if we identify the real number x with the Q-vector space Q[x], it would make sense to say that "x is infinite" because, the Q-vector space Q[x] is indeed of infinite dimension. But then, that's not what mathematicians do). I think Vi Hart made a video where she addresses this issue (or was it someone else?). Anyway, I might come to that point some other time in the future.
:::Okay, so now let's first prove the protip formula. Well first, here is the link that the explainxkcd wiki points to: [http://math.stackexchange.com/questions/140388/how-can-one-prove-cos-pi-7-cos3-pi-7-cos5-pi-7-1-2]. Most of them are correct. Some are more ugly than others. I'll adapt the last one.
::: We need a [http://en.wikipedia.org/wiki/Complex_number complex numbers]. (I choosed this because I think explainxkcd readers are fine with this. See comic [http://explainxkcd.com/179/ 179]). I will be using dots to show the steps of my proof. Please allow me an extra level of indent for clarity's sake.
:::'''Proof'''
:::: *Let z be a primitive 14-th [http://en.wikipedia.org/wiki/Root_of_unity root of unity] (the reader doesn't need to understand the 3 last words). Just say z = exp(i*pi/7) = cos(pi/7) + i sin(pi/7). Using [http://en.wikipedia.org/wiki/Euler%27s_formula Euler's formula].
:::: *We have z^14-1 = (exp(i*pi/7))^14-1 = exp(i*2pi) - 1 = 0. Using exponential law for integer powers, as seen in this article: [http://en.wikipedia.org/wiki/De_Moivre%27s_formula De Moivre's formula].
:::: *Now let's factor: z^14-1 = (z^7-1)(z^7+1) = (z^7-1)(z+1)(z^6-z^5+z^4-z^3+z^2-z+1) = (z^7-1)(z+1)*Phi_14(z). where Phi_14(X)= X^6-X^5+X^4-X^3+X^2-X+1, (see [http://en.wikipedia.org/wiki/Cyclotomic_polynomial cycltomic polynomial]). Now, because z^7-1 = (exp(i*pi/7))^7-1 = exp(i*pi)-1 = -2. And because z is not -1, the two first factors are not 0 so, Phi_14(z) = 0, which is already a pretty awesome equality.
:::: *Note that exp(i*pi/7)*exp(i*6pi/7)= exp(i*pi)=-1. So the inverse of z is -exp(i*6pi/7). But we also know that it is exp(-i*pi/7). Well. That was just a fancy way to prove that exp(-i*pi/7) = - exp(i*6pi/7). Good enough. The same holds for exp(-i*3pi/7) = exp(i*14pi/7)*exp(-i*3pi/7)=exp(i*11pi/7)=exp(i*7pi/7)*exp(i*4pi/7)=-exp(i*4pi/7). And the exact same calculation shows that exp(-i*5pi/7)=-exp(i*2pi/7). Alright.
:::: *Now, use that for any x, we have cos(x) = (exp(ix)+exp(-ix))/2. See [http://en.wikipedia.org/wiki/Euler%27s_formula#Relationship_to_trigonometry here]. Let's calculate twice the sum of the left hand side. 2(cos(pi/7)+cos(3pi/7)+cos(5pi/7))= exp(i*pi/7) + expi(-i*pi/7) + exp(3pi/7) + exp(-3pi/7) + exp(5pi/7) +exp(-5pi/7) = exp(i*pi/7)-exp(i*2pi/7)+exp(i*3pi/7)-exp(i*4pi/7)+exp(i*5pi/7)-exp(i*6pi/7) = -Phi_14(z) +1 = 1.
:::: * So dividing both sides by 2, we get what we want. Pfew.
::: '''Why is 7 so special? Well it isn't.''' Let's prove it for 9.
::::* Let z = exp(i*pi/9) = cos(pi/9) + i sin(pi/9). We have z^18-1 = 0, and z^9-1 and z+1 are not 0, so using the same factorisation, Phi_18(z) = z^8-z^7+z^6-z^5+z^4-z^3+z^2-z+1 = 0.
::::* Hence, the conclusion follow from: 2(cos(pi/9) + cos(3pi/9) + cos(5pi/9) + cos(7pi/9)) = exp(i*pi/9) + exp(-i*pi/9) + exp(i*3pi/9) + exp(-i*3pi/9) + exp(i*5pi/9) + exp(-i*5pi/9) + exp(i*7pi/9) + exp(-i*7pi/9) = -Phi_18(z)+1 = 1.
::: Well, well. I hope you kinda see the pattern. Dgbrt, I know you hate typos, and I'm pretty sure that in this long text lay many of them. So I apologize, and I will correct them later. The following paragraph was posted after I started my text but before I finished mine. It wasn't signed so I will just leave it down there. It's another valid straightforward proof. Oh. And Friendly TIP: Don't say protip when you're not pro. [[User:Varal7|Varal7]] ([[User talk:Varal7|talk]]) 21:50, 17 May 2014 (UTC)

The valid identity cos(pi/7)+cos(3pi/7)+cos(5pi/7)=1/2 was correctly proved by the writer at 108.162.216.74 above. For a different proof, consider the complex number z = cos(pi/7)+i sin(pi/7) corresponding to rotation of the complex plane by pi/7 radians, i.e., 1/14th of a full rotation. It satisfies z^{14} -1 = 0 (z to the fourteenth is one). Dividing by z-1 gives z^{13} + z^{12} + ... + z + 1 = 0. The same argument, starting with z^2 corresponding to 1/7th of a full rotation, gives z^{12} + z^{10} + ... z^2 + 1 = 0. Taking the difference, we get z^{13} + z^{11} + ... + z^3 + z = 0. Looking only at the real parts, we get cos(13pi/7) + cos(11pi/7) + cos(9pi/7) + cos(7pi/7) + cos(5pi/7) + cos(3pi/7) + cos(pi/7) = 0. Here cos(13pi/7) = cos(pi/7), cos(11pi/7) = cos(3pi/7) and cos(9pi/7) = cos(5pi/7), since cos is even and 2pi-periodic. Finally cos(7pi/7) = -1, so 2(cos(pi/7) + cos(3pi/7) + cos(5pi/7)) - 1 = 0, which you can rewrite as the desired identity. All of this can be clearly visualized using a regular 14-gon, so a proof with pictures is possible. {{unsigned ip|141.101.81.216}}

;99 is sexual reference?

In first explanation it says: "99^8 and 69^8 are sexual references". 69 I understand, but what would 99 refer too?
--[[Special:Contributions/173.245.53.167|173.245.53.167]] 17:38, 18 May 2014 (UTC)
: see [[487: Numerical Sex Positions]][[Special:Contributions/141.101.70.181|141.101.70.181]] 15:33, 20 July 2014 (UTC)

I'd add pi = (9^2 + (19^2)/22)^(1/4) [[Special:Contributions/198.41.230.73|198.41.230.73]] 02:41, 13 May 2015 (UTC)

'''Yet another proof of cos(π/7) + cos(3π/7) + cos(5π/7) = 1/2''' — Use the multi-angle formula cos(7θ) = 64(cos θ)^7 − 112(cos θ)^5 + 56(cos θ)^3 − 7(cos θ),
and assume cos(7θ)=−1; then 7θ=π, 3π, 5π, 7π, etc.
Let x=cos θ, then x = cos(π/7), cos(3π/7), cos(5π/7), cos(7π/7), etc. 
Now one could actually solve 64x^7 − 112x^5 + 56x^3 − 7x + 1 = (x+1)(8x^3 − 4x^2 − 4x + 1)^2 = 0,
but it’s easier to argue that cos(π/7), cos(3π/7), cos(5π/7) are the 3 roots of the cubic equation 8x^3 − 4x^2 − 4x + 1,
and so (using the relationship of the roots and the coefficients) their sum is −(−4)/8 = 1/2.
[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 08:19, 17 February 2019 (UTC)