explain xkcd - User contributions [en]

3036: Chess Zoo

2025-01-10T19:21:38Z

172.68.34.28: /* Explanation */ Mating in captivity

{{comic
| number = 3036
| date = January 10, 2025
| title = Chess Zoo
| image = chess_zoo_2x.png
| imagesize = 740x1221px
| noexpand = true
| titletext = The zoo takes special care to keep kings separated from opposite-color pieces as part of their conservation program to prevent mating in captivity.
}}

==Explanation==
{{incomplete|Created by a PAWN PROMOTED TO A BOT - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
A zoological garden, or {{w|zoo}} for short, is a large encampment where various animals are helped to live in small enclosures. Zoos generally serve dual purpose as both a public exhibition and a safe breeding ground for conservation efforts.

Randall has here created a zoo for giant chess pieces, as if they were animals.

There are many subtle "jokes" in the images that plays on how chess pieces moves. For example, the bishops don't need to be fully enclosed, and a narrow corridor with one white and one black square suffices to prevent them from leaving. The knight enclosure is also structured in a way that almost allows it to escape (since it can jump), but prevent it by carefully placing some fence in exactly the right place. Each side in a chess game starts with two bishops, one on each color square, and bishops can move only to squares of the same color as the one they started on. Opposing bishops on opposite color squares can never capture one another, and can therefore be kept safely in the same enclosure in the hypothetical zoo. The pawn enclosures will keep them inside even after they promote into any piece.

"Pawns promoting" refers to moving a pawn to the final rank (the opponent's back rank), which allows it to be exchanged for a queen, rook, knight, or bishop.

The phrase "mating in captivity" in the title text is typically used to refer to animals in zoos copulating, hopefully producing offspring. In this case, however, "mating" is used in the chess context, meaning delivering an attack from which the opponent's king cannot escape. To prevent this from occurring, kings are not kept in the same enclosure as any piece of an opposing color. In fact, only opposing bishops on opposite colors are shown together in this zoo.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

{{comic discussion}}

3036: Chess Zoo

2025-01-10T19:11:25Z

172.68.34.28: /* Explanation */ Don't need two "therefore"s

3036: Chess Zoo

2025-01-10T19:10:47Z

172.68.34.28: /* Explanation */ Typo

3036: Chess Zoo

2025-01-10T19:10:28Z

172.68.34.28: /* Explanation */ Bishops remain on their same color squares

3016: Cold Air

2024-12-30T12:15:00Z

172.68.34.28: Add a single missing period.

{{comic
| number = 3016
| date = November 25, 2024
| title = Cold Air
| image = cold_air_2x.png
| imagesize = 713x283px
| noexpand = true
| titletext = We also should really have checked that the old water tower was disconnected from the water system before we started filling it with compressed air.
}}

==Explanation==
{{w|Tornadoes}} are vortex-driven air columns that rotate at high speeds. The [https://www.weather.gov/ffc/fujita wind speeds can vary] from as low as 40 mph (65 km/hr), which is enough to do minor damage to some buildings and trees, to over 300 mph (480 km/hr), which is enough to level buildings, lift houses in the air, and throw automobiles at high speeds. These columns can travel over distances of several miles, causing significant damage and loss of life. Because specific conditions are required for tornado formation, certain regions are particularly prone to tornado activity (such as {{w|Tornado Alley}} in the US). These areas face ongoing threats from tornados, and so detecting and preparing for them is a major concern. The ability to dissipate a tornado before it does any damage would be very valuable.

In this strip, Cueball proposed a method for tornado control. He reasons that, since tornados depend on an inflow of warm, moist air, injecting a flow of cold, dry air should disrupt the cell. In order to protect inhabited areas, he suggests that large tanks of compressed air should be constructed in cities in tornado-prone areas to produce "pools" of cold dry air. The implication is that, if a tornado approaches, the tanks can be used to flood the area with cold air, which would settle near the ground and be drawn up into the tornado, as it approaches, hopefully causing the tornado to disperse.

Whether such a system could potentially work is questionable. For one thing, the volume of air would be so vast, and air movement in such scenarios is so hard to predict, that getting enough cold air into the tornado would be extremely difficult. In addition, it's precisely the mixing of warm and cold air that produces the swirling motion that creates tornadoes. How, exactly, this cold air would interact with the tornado is a matter of speculation. However, the final panel suggests that the plan failed for more basic reasons. Storing the vast quantity of air required would be a massive engineering challenge. The final chart refers to the point where "giant experimental compressed air tanks" are installed in populated areas, and shows that wind damage massively increased after this happened. The implication is that wind damage caused by the tanks themselves far outstripped the effects of tornadoes. The massive, discrete spikes suggest that this is caused by specific, major, damage events.

According to the label on the proposed tank, it would be pressurized to 3,000 psi. Given the scale of the buildings in the picture, the tank must be vast, possibly hundreds of feet in diameter. Simply building a tank that large to hold that kind of pressure would be exceptionally difficult, and any failure would be potentially catastrophic. Any kind of release from the tanks, whether due to valve failure (or accidental opening), pipes failing or being damaged, or the tank itself developing a rupture, would release very high pressure air, potentially at sonic velocities. Given the size of the tank, the amount of air released could be huge, and it would be directly adjacent to buildings, creating high risk of major damage. Because this damage would be done by moving air, it could be considered "wind damage", even though it's artificially generated.

An even greater danger would be if the tank were to burst altogether, which is a real danger in pressurized vessels. A sudden and uncontrolled release of air at 3000 psi is effectively an explosion. Given the enormous size of the tank, that explosion would quite certainly be enough to level the surrounding buildings.

The upshot is that, even if this proposal could fulfill its intended purpose (and it's not clear that it would), the risks that it would introduce would massively outweigh any benefits.

In the title text, it is revealed that the water tower they were using to store the compressed air was still plumbed in to the water mains. Given the pressure required for the tower to work properly against tornadoes and the fact that water is nearly incompressible, the pressure from the tower would have been nearly instantly transmitted into the water distribution system. The ''best'' case scenario would have been 'just' to have dangerously highly-pressurised water jetting into sinks, bathtubs and toilet cisterns whenever they were used; more severe consequences could be catastrophic failures of pipes and plumbing.

Using technology to disrupt tornadoes before they form was a plot element in Liu Cixin's novel ''{{w|Ball Lightning (novel)|Ball Lightning}}'', and [https://memory-alpha.fandom.com/wiki/Weather_Modification_Net other works]. In reality, fringe scientist {{w|Prokop Diviš}} (1698-1765) proposed a weather-control machine to disrupt thunderstorms before they form, and there are occasionally [https://eu.usatoday.com/story/news/weather/2019/08/26/nuke-hurricane-why-donald-trumps-reported-idea-wouldnt-work/2118430001/ discredited ideas] made to control other weather events.

==Transcript==
:[Cueball is in front of a diagram of a tornado with a pointer in his right hand. The diagram has arrows flowing from the bottom toward the tornado at the top, and from the tornado toward the rain below it.]
:Cueball: Tornado supercells are powered by the inflow of warm, moist surface air.

:[Cueball is now in front of a representation of his compressed air tank marked as having a PSI of 3000 next to smaller buildings, appearing to be high-rise buildings or skyscrapers, on both sides of the tank.]
:Cueball: Compressed air tanks could produce artificial pools of cold, dry air on demand, disrupting tornado inflow to protect cities.

:[Cueball is in front of a line graph labeled "Wind Damage over Time". Wind damage has spiked constantly after a point on the graph labeled "Giant experimental compressed air tanks installed in the middle of every major city". In the frame in the top left corner, there is a label:]
:Several years later:
:Cueball: In retrospect, I can see how my plan went wrong.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Tornadoes]]
[[Category:Line graphs]]

Talk:3014: Arizona Chess

2024-11-20T17:24:36Z

172.68.34.28:

I added a basic explanation, how did I do? [[Special:Contributions/172.70.115.129|172.70.115.129]] 14:56, 20 November 2024 (UTC)
:''pat pat'' Good job. [[User:Fephisto|Fephisto]] ([[User talk:Fephisto|talk]]) 15:28, 20 November 2024 (UTC)
I guess chess timers work based on the IERS. [[Special:Contributions/172.71.223.126|172.71.223.126]] 15:32, 20 November 2024 (UTC)

If white hat had conserved 20 seconds through the course of the game, they would have won. Cueball must have been sweating if they were relying on this strategy. [[User:Radialsymmetry|Radialsymmetry]] ([[User talk:Radialsymmetry|talk]]) 15:35, 20 November 2024 (UTC)

Here's one building that might qualify (it appears to be a shed or outbuilding belonging to a house in Mesquite, Nevada): https://www.google.com/maps/@36.808703609641505,-114.05009436731552,55m
I believe that's the only one that straddles the Arizona border with a Pacific Time Zone state (California and Nevada), so canonically, that's where the comic is set.

==North America vs. Europe==
One difference between the way parts of North America change time and the way parts of Europe do is that the various North American time zones fall back/jump forward at 2AM local time, while European time zones all change at the same instant (01:00 UTC/WET (02:00 CET, 03:00 EET). That means that the same "trick" could work by sitting on the line between any American time zones at the changeover, but not by sitting on the European lines. [[Special:Contributions/172.70.47.138|172.70.47.138]] 15:37, 20 November 2024 (UTC)

Should the comment about Hawaii be kept? It seems irrelevant. [[Special:Contributions/172.70.111.129|172.70.111.129]] 15:42, 20 November 2024 (UTC)
:removed [[user talk:lettherebedarklight|youtu.be/miLcaqq2Zpk]] 16:15, 20 November 2024 (UTC)

== Which songs would go well with this scene? ==

His World comes to mind... [[User:CalibansCreations|'''<span style="color:#ff0000;">Caliban</span>''']] ([[User talk:CalibansCreations|talk]]) 17:13, 20 November 2024 (UTC)

1455: Trolley Problem

2019-12-08T20:38:13Z

172.68.34.28: One of the main parts of this comic that makes it funny is that Black hat doesn't know about how he would kill one person by flipping the lever - He is simply questioning whether his personal disruption is worth five people's lives.

{{comic
| number = 1455
| date = December 3, 2014
| title = Trolley Problem
| image = trolley_problem.png
| titletext = For $5 I promise not to orchestrate this situation, and for $25 I promise not to take further advantage of this ability to create incentives.
}}

==Explanation==
The {{w|trolley problem}} is a thought experiment often posed in {{w|philosophy}} to explore moral questions, with applications in {{w|cognitive science}} and {{w|neuroethics}}. The general version is that an out of control trolley (or train) is heading towards 5 people on the track who can't get out of the way. On an alternative branch of the track is 1 person who can't get out of the way. The trolley can be diverted by using a lever, with the consequence of saving the 5 people but killing the 1 person. The question posed is whether or not it is morally right to pull the lever.

This results of [http://www.philosophyexperiments.com/fatman/Default4.aspx this test] report that around 86% of respondents choose the utilitarian option of diverting the trolley. Utilitarian ethics holds that the morally correct option is that which results in the most amount of good for the greatest number of people; in this case choosing to sacrifice the 1 person for 5 people.

After discovering a variation on this problem posed in a strip of the [http://www.smbc-comics.com/?id=3556#comic Saturday Morning Breakfast Cereal] webcomic (which can be seen on the tablet he is carrying), [[Rob|Cueball]], Black Hat's roommate, presents it to [[Black Hat]]. Before Cueball can finish explaining the problem, most notably leaving out the disadvantage to flipping the lever where it would kill one person, Black Hat questions whether he would need to get up to reach the lever and how much it would interrupt his other activities. As usual, he cares nothing at all about what happens to other people. This response is linked to another theory in philosophy, that of {{w|self interest}} or {{w|egoism}} or {{w|Objectivism (Ayn Rand)|Objectivism}}, in which a person will choose the action with the most benefit for them personally.

Black Hat then poses an offer: he promises to divert the trolley if Cueball is one of the five endangered people, provided that Cueball pays him $1 now. Again Black Hat is twisting the situation to his own benefit, in this case monetary. In the case of self-interest, the $1 could be the price at which Black Hat values his time and effort, below which he feels there is no benefit to himself in pulling the lever. Cueball decides that there is no point posing the problem to someone like Black Hat and gives up. This further shows that it is challenging for people with different ethical frameworks to function together without a common understanding, either mutually or with one side using that understanding to motivate a mutually agreeable or horrible solution.

The title text follows this up by continuing Black Hat's offers. For $5 he will not deliberately arrange this situation and for $25 he will quit looking for further incentives. These attempts to exploit the thought exercise for personal gain further demonstrate Black Hat's cynical amorality.

Black Hat's offer makes Cueball himself the subject of the trolley problem: Cueball now has a choice of expending $1 to save 5 people while sacrificing one person, or $5 to save all 6 people. Of course, he could dismiss the offer as a joke, if not for the person making it, which, as we know from other comics, is very much capable of such exploits.

==Transcript==
:Cueball: Ever heard of the trolley problem?
:Black hat: No. What is it?

:Cueball: A trolley is barreling towards five helpless people on the tracks. You can pull a lever to direct it onto another track, but-

:Black hat: Can I reach the lever without getting up?
:Cueball: Wait, I'm not-
:Black hat: In this scenario, how busy am I?

:Cueball: I guess I forgot who I was talking to.
:Black hat: For a dollar, I'll promise to pull the lever if one of the five people is you.

==Trivia==
*Three years later two comics were released with about one month between them where the Trolley problem was mentioned. In [[1925: Self-Driving Car Milestones]] it is in the last ''milestone'' on the list and a month later, in [[1938: Meltdown and Spectre]], it is used as a metaphor for the way some computer programs work.

{{comic discussion}}
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Philosophy]]
[[Category:Comics with color]]

Talk:2230: Versus Bracket

2019-11-18T21:09:11Z

172.68.34.28:

Because I didn't know: https://en.wikipedia.org/wiki/Ballistic:_Ecks_vs._Sever - "Ballistic: Ecks vs. Sever is a 2002 action thriller film directed by Wych Kaosayananda (under the pseudonym of "Kaos"). The film stars Antonio Banderas and Lucy Liu as opposing secret agents who team up to fight a common enemy. It is an international co-production between Canada, Germany and the United States.
The film has been called one of the worst ever made. At the box office, it made $19.9 million on a $70 million budget. With a total of 117 reviews, the highest for a film with a 0% score, Ballistic: Ecks vs. Sever is the worst reviewed film in the history of Rotten Tomatoes." [[User:Afbach|Afbach]] ([[User talk:Afbach|talk]])

Some of these matchups have relatively clear outcomes, e.g. Ford beat Ferrari (at least in the movie), and presumably we can say Kramer won Kramer v. Kramer (well, everybody lost, but...). That in mind, if we fill out the bracket with such nominal wins that lead to matchups, (Kramer v. Ford), do we learn anything interesting? And what does the resulting bracket look like? [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 18:44, 18 November 2019 (UTC)

Should a table of all the match-ups and their sources be made? --[[Special:Contributions/162.158.246.28|162.158.246.28]] 19:16, 18 November 2019 (UTC)

Should this be referencing the other time (or times?) Randall made a silly brackets where all first-round matchups are based on actual oppositions in a particular theme? I'm thinking of [https://xkcd.com/2037/|2037: Supreme Court Bracket]. Also I kinda wonder what happens when the winners of these two brackets clash. [[Special:Contributions/91.164.113.87|91.164.113.87]] 19:22, 18 November 2019 (UTC)

Added this to the Tournament Bracket category for just that reason. [[Special:Contributions/172.69.63.145|172.69.63.145]]

I stole the description directly from [[2037|Supreme Court Bracket]], is that okay? [[User:Duraludon|Duraludon]] ([[User talk:Duraludon|talk]]) 20:22, 18 November 2019 (UTC)

The winner of Freddy vs. Jason is unclear. Freddy's head is severed but he then winks and you hear his laughter implying it is another trick. That is a reoccurring thing with Freddy.

I was excited to see the winner of the bracket. Scott Pilgrim vs Kramer? [[Special:Contributions/172.68.34.28|172.68.34.28]] 21:09, 18 November 2019 (UTC)

Talk:2009: Hertzsprung-Russell Diagram

2018-06-23T05:07:48Z

172.68.34.28: explanation of the title-text joke

How the heck is a lava cake more luminous than a campfire? {{unsigned ip|108.162.219.28}}
:It's Lava '''Lake''', as in a large puddle of lava.[[User:Cgrimes85|Cgrimes85]] ([[User talk:Cgrimes85|talk]]) 15:45, 20 June 2018 (UTC)
:: Now the real question is, Why isn't lava cake included on the diagram?!?! [[User:Veleek|Veleek]] ([[User talk:Veleek|talk]]) 23:54, 20 June 2018 (UTC)
::: It would be to the left and below the astronomer. While it is hotter, the cake is a better insulator than the human, so doesn't dump as mach heat, even though it is hotter. [[User:Nutster|Nutster]] ([[User talk:Nutster|talk]]) 13:15, 22 June 2018 (UTC)
:This is the best misreading that I've seen in a while! [[User:Quantum7|Quantum7]] ([[User talk:Quantum7|talk]]) 07:56, 21 June 2018 (UTC)

As it's a logarithmic scale, is it more correct to say the plot been expanded to 1 on both axes? [[User:Cgrimes85|Cgrimes85]] ([[User talk:Cgrimes85|talk]]) 15:47, 20 June 2018 (UTC)

It seems Randall thinks an astronomer is about as bright as a lightbulb, probably due to the Hertzsprung-Russell diagram itself! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 15:52, 20 June 2018 (UTC)
:A daily food consumption of average human is about 100W when spread out over 24 hours
::It might actually be about that bright, but in the infrared spectrum. http://elte.prompt.hu/sites/default/files/tananyagok/InfraredAstronomy/ch01s04.html [[Special:Contributions/108.162.246.89|108.162.246.89]] 20:54, 20 June 2018 (UTC)
:But they are no where near as hot!
::You seem to overestimate the attractiveness of most lightbulbs. I've only seen a few that I would consider really hot.
[[Special:Contributions/172.69.198.10|172.69.198.10]] 20:57, 20 June 2018 (UTC)
:::And size; Remember that this type of chart is for comparing total luminosity to surface temperature, & although light bulbs get hot, they're usually nowhere near the surface area of an astronomer.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

While wattage is used as an informal proxy for bulb brightness, there is not a 1-to-1 relationship between power consumption and light output. Incandescent bulbs in the United States were commonly labeled with both watts consumed and lumens output to aid consumers in choosing efficient bulbs.
:"Were"? When? These days the lamp itself usually only states volts & watts, & you're lucky if even the box states lumens. My personal least-favorite is "60w equivalent" with no color temperature & no luminosity listed.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

{{w|Ivanpah Solar Power Facility|Ivanpah}} doesn't have a salt tank. Presumably he meant the boiler, and/or was confusing it with {{w|Crescent Dunes Solar Energy Project|Crescent Dunes}}.
[[User:Wwoods|Wwoods]] ([[User talk:Wwoods|talk]]) 17:29, 20 June 2018 (UTC)
:Thank you! That had me scratching my head. I bet he was thinking of Crescent Dunes. Should this be noted in the Explanation?[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

I understand the explanation, but what's the joke?

The title text says "The Hertzsprung-Russell diagram is located in its own lower right corner, unless you're viewing it on an unusually big screen." But it's clearly on the top left corner... Am I missing something? [[Special:Contributions/108.162.219.106|108.162.219.106]] 18:47, 20 June 2018 (UTC)

:Why would it be at the top left...? The diagram itself is not particularly luminous, so would not be at the top, and its apparent temperature is quite low, so it would not be on the left.

::The joke is that while these type of graphs are typically used for illustrating the output of stars in relation to their age; Randall has extended its range to apply it to planets, boats, whales, & astronomers. Most items in the lower right are neither very luminous (compared to the total luminosity of a star) nor very hot (as compared to a star) & certainly their output on either scale does not bear a reliable correlation to their age. Randall is once again weighing things with the wrong measuring stick, so to speak.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

:::Adding to this, the title text is joking that if you were to measure the diagram's luminosity and effective temperature, then place a point representing that on a copy of the diagram, the resulting point would be in the copy's lower right corner. This type of joke is similar to the one in 688: Self-Description. [[Special:Contributions/172.68.34.28|172.68.34.28]] 05:07, 23 June 2018 (UTC)

Why is a blue whale considered more luminous than a campfire? Blue whales don't generate any light.
:It would if your took it out of the water (to reduce convective losses), but it would emit in the infrared. The 78 kW cited here would equate to 588 million kcal of krill per year. That's in the ballpark of other estimates I found (e.g. 490 million[https://www.washingtoncitypaper.com/columns/straight-dope/article/13041278/straight-dope-does-the-average-american-use-more-energy-than]). I agree that this is one of the more surprising facts to find on this chart. --[[User:Quantum7|Quantum7]] ([[User talk:Quantum7|talk]]) 08:10, 21 June 2018 (UTC)
:: Size counts for a lot of that. By ounce, a campfire would be hotter, but these graphs go by total, not per-ton of mass.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

In one of the interesting parts of this diagram not that many mundane objects (or at least smaller than earth objects) are much hotter than most stars (surface temperature)... Not mentioned now.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 20:33, 20 June 2018 (UTC)
:I'm beginning to think the Explanation should highlight the fact that these graphs go by total output, not output per kilogram or anything relative like that. Body temperature of a blue-whale is almost certainly higher than the average temperature of a cruise ship, but a cruise ship is *much* bigger, thereby almost certainly outputting more heat. That said, I'm pretty sure these charts are only supposed to go by ''surface'' thermal output, which could throw a lot of these listings way off. Anyone know what the ''surface'' temperature of a blue-whale is? I've never seen one shown in infrared.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

I think the current explanation is still taking some of the graph too literally, thereby missing some of the jokes. After all, Randall creates comics, sometimes using innuendo or subtlety to make a point. I still think some of the items on the graph are plotted using luminosity as a measure of "brightness" in the sense of smartness. No offense intended, but he must have had a reason for including France below the planets and the blue whale above the astronomer. Furthermore, the title text is likely talking about the actual HR diagram not being very "bright" in the same way the astronomer is in the lower-right corner of the graph, except when it is displayed on a jumbotron. If you're an astronomer, you might not like hearing this, but the meaning of the HR diagram is difficult to grasp correctly. To leave out any mention of smartness is likely missing the most significant jokes in the comic. Please feel free to disagree, but remember it's still just a comic! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 00:37, 21 June 2018 (UTC)

: More specifically to my point, this part of the explanation
:: "the title text notes that the screen displaying the diagram would probably be plotted..."
: is not correct. The title text states the diagram itself would probably be plotted in the lower-right corner, not the screen displaying it - the screen was only related to the second part of the title text! This IS the primary joke in the comic and likely why Randall is making fun of it in the first place. This is also likely the reason for the astronomer to ALSO be plotted in this corner - I doubt that is just a coincidence. Maybe Randall was too subtle for his point to get through to readers! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 04:37, 21 June 2018 (UTC)

: Just in case I'm also being too subtle, I think Randall is saying that the HR diagram is neat to look at (as in really cool) but also stupid (as in not very bright), putting it in the lower-right corner of itself (cool and dim)! There, I said it! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 04:45, 21 June 2018 (UTC)

::I believe it is definitely about total luminosity & thermal output, ''not'' "brightness" as a measure of intelligence. France is below the planets because it has much less total surface area & thereby less luminosity than the planet itself. If the graph listed by average luminosity per square inch, France would be higher than Earth. There is no joke about intelligence here, only that total luminosity & total heat output are not reliably linked to the age of non-stellar scale objects.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

:::I will concede on the question of intelligence related to objects on the diagram, as various comments have clarified each such object. Note that the detail on Venus needs to be fixed per another comment here suggesting it's not an error, and I'm pretty sure Randall meant Europa rather than mistyping Europe, so that should be removed from the explanation too. However, the title text explanation is still wrong - it is not about the display of the diagram but the diagram itself. This needs to be addressed! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 01:44, 22 June 2018 (UTC)

How come this diagram says an LED bulb is hotter than a lightbulb, and both are hotter than a campfire? That doesn't seem right. [[User:YM Industries|YM Industries]] ([[User talk:YM Industries|talk]]) 01:49, 21 June 2018 (UTC)
:The confusion is coming from the fact that the arrow at the top is pointing toward lower temperatures. I'm not sure if this is intentional, or if it is a mistake, but seems to be confusing a lot of people (including myself until I read the actual numbers)[[User:Probably not Douglas Hofstadter|Probably not Douglas Hofstadter]] ([[User talk:Probably not Douglas Hofstadter|talk]]) 03:09, 21 June 2018 (UTC)
:: I noticed that the arrow was pointing in a confusing direction, but LED bulb is to the left of the campfire. The diagram clearly says it's hotter. I'm very confused by this comic. [[User:YM Industries|YM Industries]] ([[User talk:YM Industries|talk]]) 05:22, 21 June 2018 (UTC)

: The location of the LED and Lightbulb temperatures may be related to the actual light source points of these objects (diode junction and wire filament) rather than the outer shells that we can touch. I don't know enough about their internal temperatures to say for sure, but that might explain their positions. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 05:05, 21 June 2018 (UTC)

:Worked it out, it's referring to the colour temperature. [[User:YM Industries|YM Industries]] ([[User talk:YM Industries|talk]]) 05:24, 21 June 2018 (UTC)
::Right. The color temperature of an LED bulb can be much higher than a blackbody of the same power and area because it emits in only a small spectral region.[[Special:Contributions/108.162.238.47|108.162.238.47]] 05:32, 21 June 2018 (UTC)
:::'''''A pun! That's another joke; Should definitely be noted in the transcript.''''' Also, if he ''were'' referring to internal temperatures, not surface temperatures, it would be the only place in this chart he seems to have done so. The other listings are consistent with surface temperatures, not average internal temps.[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 14:25, 21 June 2018 (UTC)

I'm pretty sure there shouldn't be a table in the transcript? I've moved it, but now the table needs to be filled and the transcript needs some work. [[User:Herobrine|Herobrine]] ([[User talk:Herobrine|talk]]) 03:10, 21 June 2018 (UTC)

Venus' temperature is correct. Randall is using planetary equilibrium temperature <ref>https://en.wikipedia.org/wiki/Planetary_equilibrium_temperature</ref> [[User:Astronorn|Astronorn]] ([[User talk:Astronorn|talk]]) 04:56, 21 June 2018 (UTC)

Seriously, can we get a mention that this graph relates to ''total'' output by surface area, not relative output by mass or anything like that? Obviously per square inch, a campfire is much more luminous than a whale, but the whale gives off more radiation in total due to its greater surface area. The distinction seems to be a source of confusion to a lot of people.

The France entry might relate to the fact that our commune here in France (Pessac, 33) now turns off its streetlights between 0100-0500; and there are many communes that do the same or use more sophisticated schemes, like motion sensors or partial extinction, and turning off lighted signage for shops, etc.. [[User:BeeVee|BeeVee]] ([[User talk:BeeVee|talk]]) 14:48, 21 June 2018 (UTC)
:If so, '''that might be another joke''': If the graph went by lumens per area of surface, ''any'' marginally developed country would be shown ''higher'' (with more light output per area) than the Earth as a whole (yes, even countries turning off most of their lights at night), ''because'' '''''oceans'''''. On the other hand, with the graph the way it ''is'' shown, even comparing France to another region of roughly equal area & average reported surface temperature it would be difficult to discern whether its placement on this graph is any higher or lower due to switching the streetlights off at night; Most populous regions of comparable area are probably well within one order of magnitude in terms of light output (citation needed?), so any two comparable regions would be within about one pixel of each other. Listing France next to a comparable region doesn't help, but ''not listing anywhere else'' actually hints at the issue in question (turning off lights)!

== Missing Next and Last buttons? ==

As I type this, an entry for comic 2010 exists, but the Next and Last buttons on 2009 don't exist. I've refreshed a bunch and also confirmed in Incognito and a different browser. So not a cache issue on my end. [[User:Davidgro|davidgro]] ([[User talk:Davidgro|talk]]) 23:07, 22 June 2018 (UTC)

Talk:1945: Scientific Paper Graph Quality

2018-01-23T02:21:33Z

172.68.34.28:

What happened circa 2015 that marks the *end* of the PowerPoint/MSPaint era? [[Special:Contributions/108.162.238.59|108.162.238.59]] 16:22, 22 January 2018 (UTC)

--> More and more journals explicitly forbade the use of powerpoint. Also, more scientists are familiar with software better suited for creating scientific graphs. [[User:Thawn|Thawn]] ([[User talk:Thawn|talk]]) 16:34, 22 January 2018 (UTC)

: The problem was never that it was impossible to good quality graphs with those tools. The problem was that people ''didn't actually'' do so, in part because the tools made it really easy to produce something superficially good but actually so information-free as to be utterly bad, as well as making it rather more difficult than one would hope for to make camera-ready graphs (journals having higher-resolution print reproduction than most computer screens of the time). But before anyone gets fancy about this, you could commit very similar sins with other tools; merely using a specialist plotting program doesn't automatically make the output truly comprehensible (or relevant). [[Special:Contributions/141.101.104.107|141.101.104.107]] 22:30, 22 January 2018 (UTC)

::If, however, creating graph is harder, you are likely to focus on what to put into them and make them only if it makes sense. One reason for decreased quality of graph might be that there was more of them for same amount of data. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 01:29, 23 January 2018 (UTC)

An interesting thing to note is that you can see from this chart that even slightly before the paint/powerpoint era the quality started going down. But it could be because this graph is meant to be just like the point it is making and therefore is not 100% accurate. [[Special:Contributions/108.162.219.76|108.162.219.76]] 17:47, 22 January 2018 (UTC)

You might find http://www.norvig.com/Gettysburg/ amusing. It is the Gettysburg Address done as a PowerPoint presentation.
[[Special:Contributions/108.162.216.154|108.162.216.154]] 18:55, 22 January 2018 (UTC) Gene Wirchenko genew@telus.net

Does anyone have good examples of papers showing this? It would really help the explanation...[[Special:Contributions/172.68.211.166|172.68.211.166]]

Also amusing is how low quality the image of this comic is. It is only 360*240 pixels, which is fitting for a graph describing low quality graphs.[[Special:Contributions/172.68.34.28|172.68.34.28]] 02:21, 23 January 2018 (UTC)

137: Dreams

2017-12-05T00:40:06Z

172.68.34.28: /* Explanation */ Explanation implied that profanity is not a potent and relative method of communication, calling it "inappropriate" when it was utterly appropriate.

{{comic
| number = 137
| date = August 4, 2006
| title = Dreams
| image = dreams.png
| titletext = In Connor's second thesis it is stated 'There is no fate but what we make for ourselves.' Does the routine destroy our creativity or do we lose creativity and fall into the routine? Anyway, who's up for a road trip!
}}

==Explanation==
In the first panel of this comic, it is clear that Cueball has just written some comment that his friend thinks will lower his chances for getting a job in the future. This is common advice given to teenagers and young professionals, given as a warning that their posts online could be seen by a potential future boss.

In the next panel, Cueball replies with a seeming non-sequitur: when did we forget our dreams? Without explanation, this seems like one of the overly philosophizing, ultimately meaningless questions that also happen to pop up on social media sites. Cueball's friend is confused by the sudden shift in conversation.

The long monologue Cueball delivers focuses around the fact that as people get older, their lives becomes narrower and less filled with possibilities and novelty. This is a speech made in the manner of someone getting older and missing the simpler days of youth, where everything was much more exciting. From this point, he explains that part of the deadening process is responding the same way to each event that happens, and creating a routine. Routines, Cueball believes, remove our ability to act on our dreams.

Finally, Cueball gets to relating this monologue to posting inappropriate material to social media sites: he will not let his concerns for a nebulous future hinder the outlook on life he has now. He will not limit his choices in order to conform with the expectations of an uninspired future. He ends with the clear and simple explanation of his choices—"Fuck. That. Shit.".

Cueball's use of periods between each word in this closing phrase is itself another reference to practices on social media sites; people will sometimes {{tvtropes|PunctuatedForEmphasis|put periods between each word in a short phrase to show emphasis.}}

Connor's second thesis from the title text is a quote from the character {{w|Sarah Connor (Terminator)|Sarah Connor}} in the film {{w|Terminator 2: Judgment Day|Terminator 2}}. The message expressed is a restatement of Cueball's monologue: While it sounds trite, each and every one of us has the ability to change our situation, whether by quitting the job we don't like, telling ''that person'' that we love them, or some other action. Our action (and inaction) creates our future, including the way in which we react to those things outside our control.

The title text also poses the question of whether the more creativity lost to conformity, the more routine life becomes, or the more routine life becomes, the less creative you become. This is a chicken and egg type question, which is dramatically broken by the suggestion of a roadtrip. This is the situationally unexpected break that shows that the speaker is willing to break out of the routines threatening to set in.

Other comics with a similar theme about finding or taking unexplored paths, instead of fitting into the mold, include [[59: Graduation]] and [[267: Choices: Part 4]].

==Transcript==
:[A friend is standing behind Cueball, who is typing at a computer.]
:Friend: You should be more careful what you write. Future employers might read it.

:Cueball: When did we forget our dreams?
:Friend: What?

:[Cueball stands beside his friend.]
:Cueball: The infinite possibilities each day holds should stagger the mind. The sheer number of experiences I could have is uncountable, breathtaking, and I'm sitting here refreshing my inbox. We live trapped in loops, reliving a few days over and over, and we envision only a handful of paths laid out before us. We see the same things every day, we respond the same way, we think the same thoughts, each day a slight variation on the last, every moment smoothly following the gentle curves of societal norms. We act like if we just get through today, tomorrow our dreams will come back to us.

:Cueball: And no, I don't have all the answers. I don't know how to jolt myself into seeing what each moment could become. But I do know one thing: the solution doesn't involve watering down my every little idea and creative impulse for the sake of some day easing my fit into a mold. It doesn't involve tempering my life to better fit someone's expectations. It doesn't involve constantly holding back for fear of shaking things up.

:Cueball: This is very important, so I want to say it as clearly as I can:

:Cueball: '''FUCK.'''

:Cueball: '''THAT.'''

:Cueball: '''SHIT.'''

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Dreams]]

1908: Credit Card Rewards

2017-10-29T17:21:08Z

172.68.34.28: Fix titletext

{{comic
| number = 1908
| date = October 27, 2017
| title = Credit Card Rewards
| image = credit_card_rewards.png
| titletext = I should make a list of all the things I could be trying to optimize, prioritized by ... well, I guess there are a few different variables I could use. I'll create a spreadsheet ...
}}

==Explanation==
{{incomplete|VERY basic explanation.}}

A credit card, at its most basic form, is a loan contract to an individual from a bank. Like all contracts, the bank will offer several different types in an attempt to appeal to a large number of individuals. Unlike traditional loans which focus on a single item (car, house, boat, etc), a credit card is an unsecured loan geared towards daily and weekly transactions. Because these transactions cover a wide variety of items, credit cards can be further tweaked towards offering benefits in certain areas. Gas purchases, or even gas purchases through a single retail chain can offer higher rewards on one type of plan vs other plans.

These benefits, typically called rewards, have several different options. "Cash back" is a reward where the individual is given money back when they make a purchase that follows certain rules spelled out in the contract. "No interest" is a reward where the individual is not charged interest on their purchases if they pay the loaned money back within a specified amount of time. "Points" are similar to the cash back program, but are typically reserved towards purchasing a single large item or plan. Points towards a vacation is a popular option. Besides these three types of rewards, the number of actual rewards to pick from are limited only by the creativity and fiscal limitations, and of the issuing bank's CEO.

Cueball is trying to choose the optimal credit card program (the one that will result in biggest savings with the yearly fiscal median (YFM) he has). He realizes that he has to subtract the cost of him spending time on optimizing, so he wants to optimize the time needed to do the optimizing. But in order to to that efficiently, he first has to optimize the time spent on optimizing the time.

Hairy notices a hidden assumption that Cueball will spend his time on something more productive than this, e.g. that his time has value. Cueball responds that he can "fail to optimize so many better things." This means that Cueball is aware both of the big flaw in his reasoning and the fact that, when he attempts to optimize things, the attempt seldom really helps his situation.

The title text further expands the idea. Cueball wants to present a list of things to optimize to Hairy. However, he still needs to optimize the priorities of that list, before optimizing the list itself. Making and working with lists like this often involves a spreadsheet, which may also be a reference to [[1906: Making Progress]].

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Cueball sits at a desk and is on his laptop. Hairy stands behind him.]
:Cueball: I'm trying to figure out which of these credit card rewards programs is best given my spending.

:[Cueball leans backwards in a frameless panel.]
:Cueball: But at some point, the cost of the time it takes me to understand the options outweighs their difference in value.

:[Close-up of Cueball's head and torso.]
:Cueball: So I need to figure out where that point is, and stop before I reach it.
:Cueball: But... when I factor in the time to calculate <i>THAT</i>, it changes the overall answer.

:[Cueball has his arms outstretched.]
:Hairy: I question the assumption that you'd otherwise be spending your time on something more valuable.
:Cueball: Come on, I could be failing to optimize so many better things!

{{comic discussion}}

[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Cueball]]

Talk:1893: Thread

2017-09-22T20:15:19Z

172.68.34.28:

Threadfall on Twitter beginning 2016? I'm not sure to what that refers. [[Special:Contributions/172.68.58.29|172.68.58.29]] 15:19, 22 September 2017 (UTC)
[[Special:Contributions/172.68.58.29|172.68.58.29]] 15:19, 22 September 2017 (UTC)
: Maybe it's referring to increased use of threaded tweets? I too have noticed an increase around that time; it was mostly screenshots of note-apps before.
:: Maybe it's a reference to Twitter stock price falling [http://www.marketwatch.com/investing/stock/twtr here] [[Special:Contributions/198.41.226.136|198.41.226.136]] 17:44, 22 September 2017 (UTC)
:"Greatest threat" on Twitter beginning 2016 - I think that's a fairly obvious @RealDonaldTrump reference. [[Special:Contributions/172.68.34.28|172.68.34.28]] 20:15, 22 September 2017 (UTC)

I loved the Dragonriders of Pern series, but I'm a little bit mystified where this came from out of the blue. It's hardly a new series. Did he just start reading it and is all excited about it? Usually it's tied to some current event or topic, rather than just an excuse to make a pun about a character from an old book... Anyone know of any relevant current events that prompted this? [[User:DevAudio|DevAudio]] ([[User talk:DevAudio|talk]]) 15:39, 22 September 2017 (UTC)

I'm not sure why he is suddenly referencing dragonriders, but I think the twitter 'threadfall' could connect to Donald Trump on twitter? But the timing is not right... I mean I guess he was elected in ''late'' 2016 so that could count. And 2016 was when he became really seriously engaged in politics and twitter in connection to that... not very strong evidence though. I could also be convinced that the date is arbitrary [[Special:Contributions/162.158.146.22|162.158.146.22]] 16:32, 22 September 2017 (UTC)

1124: Law of Drama

2017-07-27T06:33:28Z

172.68.34.28: /* Explanation */ Removed incomplete explanation identifier.

{{comic
| number = 1124
| date = October 22, 2012
| title = Law of Drama
| image = law of drama.png
| titletext = 'Drama' is just 'people being upset,' when someone says they're always surrounded by drama and they just ignore it, it starts to make sense that their strategy might be backfiring.
}}

==Explanation==
The comic comments on how often people who label themselves as an innocent party in a debate are often far from it. Essentially, [[Randall]] seems to be graphically stating that people who claim to want to avoid drama are invariably associated with it. Since [http://www.explainxkcd.com/wiki/index.php/552:_Correlation correlation does not imply causation], it might be a leap — at least scientifically speaking — to actually surmise that they're the cause of it.
The title text suggests that the person's attitude towards drama is wrong. Supposing that "'Drama' is just 'people being upset'", then ignoring drama is a very bad way to deal with it. By ignoring people's problems, you certainly won't be able to help them, and are at risk of causing further problems through ignorance.

==Transcript==
:[A Cartesian graph labelled 'How often someone declares that they hate "drama" and always avoid it' on the x axis and 'Rate at which they create drama' labelled on the y axis. The graph is a slightly exponential curve sloping upwards.]

{{comic discussion}}

[[Category:Line graphs]]
[[Category:Psychology]]

1862: Particle Properties

2017-07-12T18:20:22Z

172.68.34.28:

{{comic
| number = 1862
| date = July 12, 2017
| title = Particle Properties
| image = particle_properties.png
| titletext = Each particle also has a password which allows its properties to be changed, but the cosmic censorship hypothesis suggests we can never observe the password itself—only its secure hash.
}}

==Explanation==
{{incomplete|Table needs to be filled out with remaining explanations}}
A table is presented comparing the range (maximum and minimum value) and scale (how big number increments are) of several measures. The table begins by listing properties pertinent to {{w|particle physics}} as the title suggests, but quickly devolves to other domains such as role-playing games (such as D&D) and sports after failing to provide a good definition of {{w|Flavour (particle physics)|flavor}}.

{| class=wikitable
! Property
! Scale
! Explanation
|-
| Electric charge
| [-1,1]
| The charge is shown in increments of a third from -1 to +1 which are the only known charges of fundamental particles (leptons, quarks and gauge bosons); however there are some exotic composite particles with twice integer charge, e.g. the recently discovered double charmed Xi baryon with a charge of +2.

Quarks are the only particles with charges of ± ⅓ or ± ⅔, but cannot exist on their own. To date, all hadrons (particles composed of quarks) have integer charge, and current models indicate that this must be the case.
|-
| Mass
| [0,∞) in kg
| Mass (specifically rest mass) is the measure of an object or particle's resistance to force, as well as its ability to distort {{w|spacetime}} (its gravitational attraction).
Theoretically, any object's mass could approach infinity, but mass cannot be below 0. Some particles, such as photons, have zero rest mass and are therefore massless.

All particles with rest mass obtain it through confinement, either by the {{w|Higgs field}} (the quarks, leptons and W, Z, and Higgs bosons) or the strong nuclear force (hadrons).
Particles with no rest mass (photons and gluons) can only move at lightspeed
|-
| Spin number
| (-∞,∞) (Intervals of ½)
| Spin is an intrinsic property of particles, a relativistic form of angular momentum. The spin of a particle determines what statistics the particle follows, half odd integer spin particles are classified as fermions and integer spin particles are bosons.

Two fermions cannot have exactly the same state, an observation known as the Pauli exclusion principle. Thus, for fermions to exist in the same position, they must have opposite spins, of + ½ and - ½. It follows that a maximum of two fermions of the same flavor (e.g. two electrons) may exist in the same position.
|-
| Flavor
| Misc. quantum numbers
| Flavor is a series of quantum numbers that do not fit neatly onto a set of dimensional axes
|-
| Color charge
| Coordinate system with R, G and B axes
| Color charge can be Red Green or Blue, the color of a particle must sum to white so a particle can be RGB or Red anti-Red or equivalent. The color charge confines the quarks, separating quarks requires so much energy that jets of particles are created, so color is a property inferred as it cannot be observed on its own. This is the last entry currently used to describe particles by particle physicists.
|-
| Mood
| 5 emojis on a number line ranging from angry to joyful
| Mood particles are not considered to have emotion but Randall implies that there is a quantized 5 point scale which would have some effect of the properties of the particle. This would be more appropriate for measuring customer satisfaction.
|-
| Alignment
| 3x3 grid with varying shades (columns Good-Evil, rows Lawful-Chaotic)
| A reference to the tabletop RPG {{w|Dungeons & Dragons}}, where characters have an {{w|Alignment (Dungeons & Dragons)|alignment}} that is either Good, Neutral, or Evil (describing whether they have a propensity to help or harm others) and either Lawful, Neutral, or Chaotic (describing how much they care about organizations, social norms, and the status quo). Common examples of these alignments include Darth Vader (Lawful Evil), Superman (Lawful Good), Robin Hood (Chaotic Good), and the Joker (Chaotic Evil). This may be a reference to the now defunct names of the two heaviest known quarks ("truth" and "beauty").
|-
| Hit points
| [0,∞)
| Games (videogames, board games, CCGs, RPGs, etc.) often have values for players and other entities that represent health (also called hit points or HP). Generally there is not necessarily a limit on this value, but it does not often go below 0 as the zero value is considered "dead" (or some equivalent).
|-
| Rating
| 5-star scale
| The five-star rating system is often used to rate films, TV shows, restaurants, and hotels. Randall has previously criticized this system in [[937: TornadoGuard]] and [[1098: Star Ratings]].
|-
| String type
| Bytestring-Charstring
| In computer science this denotes what type of data is stored subsequent set of elements or a {{w|String_(computing)|string}}. This is likely a pun on {{w|String_(physics)|string}} types that appear in {w|string theory}} and particle physics.
|-
| Batting average
| [0,100] in %
| In {{w|baseball}}, a player's {{w|batting average}} is calculated by dividing their hits by their at-bats. Instead of using the percent sign (%), it is usually presented as a number between 0 and 1 (inclusive) expressed as three decimal places with no leading zero: [.000, 1.000]. It is pronounced as though it is multiplied by 1,000: A batter with a batting average of .342 (which is very good) is said to be "batting three forty-two." A perfect batting average (unattainable except in very small samples) gives rise to the expression "batting a thousand." The scale would be a better match for the batting average statistic in {{w|cricket}}.
|-
| Proof
| [0,200]
| This refers to {{w|alcohol proof}}, which is the measure of the amount of ethanol in a beverage by volume. In the United States, the proof of a beverage is two times the percentage of ethanol, so the maximum value is 200.
|-
| Heat
| No jalapeño icons - 3 jalapeño icons, increasing
| Spicy peppers are measured by the intensity of the spicy flavor, usually ranging from values like "mild" to "hot". The gray jalapeño likely represents negligible or no spicy taste in the food.
|-
| Street value
| [0,∞) in $
| The value of an illegal good or a legal/controlled good when bought or sold by illegal means.
|-
| Entropy
| ''This already has like 20 different confusing meanings, so it probably means something here, too.''
| The term "entropy", which {{w|History of entropy|began}} as a {{w|Entropy (classical thermodynamics)|thermodynamic measure}}, has since been adopted {{w|Entropy in thermodynamics and information theory|by analogy}} into {{w|Entropy (disambiguation)|multiple seemingly unrelated domains}}. The table doesn't seem to know what domain it is in, but (possibly in a desperate attempt to hide this) deems it safe to assume the unknown domain uses the term "entropy" for ''something''!
|}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:<big>Particle Properties in Physics</big>
{| class=wikitable
! Property
! Type/scale
|-
| Electric charge
| [Scale with -1, 0 and +1 labeled]
|-
| Mass
| [Scale with 0, 1kg and 2kg labeled]
|-
| Spin number
| [Scale with -1, -½ 0, ½ and 1 labeled]
|-
| Flavor
| (Misc. quantum numbers)
|-
| Color charge
| [3D plot with R, G and B axes] (Quarks only)
|-
| Mood
| [Scale labeled with 5 emoticons, from angry to happy]
|-
| Alignment
| [3x3 grid with varying shades] Good-Evil, Lawful-Chaotic
|-
| Hit points
| [Scale starting from 0]
|-
| Rating
| [Star rating of 3.5/5 stars]
|-
| String type
| Bytestring-Charstring
|-
| Batting average
| [Scale from 0% to 100%]
|-
| Proof
| [Scale from 0 to 200]
|-
| Heat
| [Scale labeled with pepper icons, from 0 to 3]
|-
| Street value
| [Scale with $0, $100 and $200 labeled]
|-
| Entropy
| (This already has like 20 different confusing meanings, so it probably means something here, too.)
|}

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

1791: Telescopes: Refractor vs Reflector

2017-01-27T15:57:05Z

172.68.34.28:

{{comic
| number = 1791
| date = January 27, 2017
| title = Telescopes: Refractor vs Reflector
| image = telescopes_refractor_vs_reflector.png
| titletext = On the other hand, the refractor's limited light-gathering means it's unable to make out shadow people or the dark god Chernabog.
}}

==Explanation==
{{incomplete|The section [[#The real problems with refractor telescopes|The real problems with refractor telescopes]] could need someone with a major in optics looking over it. And probably the rest could also be smartened up?}}
This comic compares two types of telescopes: {{w|Refracting Telescope}} vs {{w|reflecting telescope}}.

It first looks like the comic is simply trying to show that refracting has many flaws, such as expense, size and visibility (see more [[#The real problems with refractor telescopes|details below]]). However, the punchline invalidates these complaints with the (apparently major) flaw listed with the reflecting telescope: It can't see space vampires.

The unstated reason for this is that {{w|vampires}}, {{w|Vampire#Apotropaics|according to some cultures}}, cannot be seen in a mirror. As {{w|space vampires}} (like earth vampires) are widely believed to be {{w|Vampire#Origins_of_vampire_beliefs|made up}} and thus unlikely to interest most stargazers, this complaint is superfluous, and the reflecting telescope effectively has no flaws in comparison to the refracting telescope.

An error in the comic would seem to be that both telescope illustrations contain a mirror (in the refracting, it's at the eyepiece). This would invalidate the advantage it has over reflecting telescopes, but as can be seen on the Wikipedia page for Refracting telescope {{w|Refracting_telescope#Refracting_telescope_designs|it does not need the mirror}} drawn by [[Randall]]. So in principle such a telescope could then see vampires that do not show up in mirrors. But Randall's version would not be able to do so because of the mirror at the base. So it is for sure an error if it should be explained by the mirror folklore. Frequently, however, the right-angle transition at the base of the refractor telescope is done with a prism (an "image erector"). This uses the optical principle of total internal reflection. Since mirror-non-appearance of vampires is presumably due to the interaction of evil with silver, the refractor could still see vampires. On this theory, however, the reflector could too, since modern astronomical mirrors are coated with aluminum, not silver.

The title text expands on the seeing of supernatural beings, as another negative point is added to the refracting telescope; it apparently can't see {{w|Shadow person|Shadow People}} or the Slavic god {{w|Chernobog}}, both of which are apparently equally important to the telescope's merit despite neither the {{w|Shadow_person#History_and_folklore|shadow people}} or {{w|Chernobog#Folklore|the god}} exists. In reality, "shadow people" are a psychological phenomenon wherein humans ascribe human shapes and movements to shadows in dark spaces. Chernabog is a 12th century Slavic diety, whose name translates to ''black god''. His most famous appearance in modern media was in the 1940 Disney movie {{w|Fantasia (1940 film)|''Fantasia''}}. Because shadows are dark and the god is also dark, they cannot be seen by the refracting telescope due to the reduced light-gathering which has already been mentioned as a drawback in the main comic.

Telescopes has been the subject of [[:Category:Telescopes|many comics]] on xkcd. Recently one about space telescope was released [[1730: Starshade]] and before that a large "private" telescope was shown in [[1522: Astronomy]].

==The real problems with refractor telescopes==
The basic performance of a telescope is determined by its size: a wider telescope catches more light, making it easier to see faint objects, while a longer telescope is better for high magnification viewing. For looking at stars, the width is actually more important. No matter how much you zoom, a star is too far away to make bigger, but with a big aperture, you can see stars too faint for the naked eye. Planets benefit more from magnification, and distant galaxies need both.

In both respects, it's much easier to make a big reflector telescope than a big refractor one. Since a lens can only be held in place by its edge, the center of a large lens sags due to gravity, distorting the images it produces. This means most reflector telescopes make do with narrow apertures only a couple of inches across. Reflector telescopes are sometimes called "light buckets" because they can have extremely big openings that can catch light from even very faint stars.

*More expensive
**It is very difficult to make a refractor telescope as large as a reflector telescope, and would thus be more expensive it it needed to be as good as the reflector telescopes used almost exclusively today.
*Less compact
**Because it has a mirror at one end, the reflector telescope is, in effect, twice as long as it appears - a reflector just cannot compete.
*{{w|Chromatic aberration}}:
**In optics, chromatic aberration is an effect resulting from dispersion in which there is a failure of a lens to focus all colors to the same convergence point, producing a rainbow effect around the image familiar to people who glasses with prisms. It occurs because lenses have different refractive indices for different wavelengths of light. Each colour is therefore focused slightly differently by the lens.
***Note that this effect has also been mentioned in relation to photography by [[Black Hat]] in [[1014: Car Problems]], in a completely different context, but shows this is an issue Randall has considered before.
*Reduced light-gathering
**Apart from generally needing to be smaller than reflector telescopes a further problem comes from glass defects, striae or small air bubbles trapped within the glass. In addition, glass is opaque to certain wavelengths, and even visible light is dimmed by reflection and absorption when it crosses the air-glass interfaces and passes through the glass itself. All of this reduce the light gathered.

It is worth noting that:
:'''A reflecting telescope also has disadvantages compared to a refracting telescope'''.
*The main disadvantage is that in almost all reflecting telescope designs the focal point is directly in front of the mirror, i.e. in between the mirror and the target of interest.
**As a result a {{w|Secondary_mirror|secondary mirror}} is commonly used to direct the focal point somewhere outside of the field of view. However, this secondary mirror (and the struts that support it) will still block part of the field of view - although the focus of the telescope means that the secondary mirror is not visible when looking at distant objects, it will result in diffraction patterns that also hinder the image quality. In fact, this is the source of the {{w|Diffraction_spike|diffraction spikes}} around stars which are commonly seen in astronomical images.
*A reflecting telescope is also harder to maintain:
**The mirrors need to be very precisely aligned (this is called collimation), and this can be a laborious process. They may also need re-polishing.
**The telescope is open at one end, allowing dust and dirt to enter.
*A reflecting telescope is not very portable. This is why birdspotters use small refractor telescopes as an easy way to get a closer view of birds.

Despite this disadvantage, reflecting telescopes are used almost exclusively in modern astronomy because of practical limitations in making large refracting telescopes. Very few amateur astronomers use refracting telescopes - nowadays, they most exist to con people looking for Christmas presents in department stores (just because a telescope promises 100x zoom doesn't mean the image quality is any good!)

==Transcript==
:[A one panel comic showing two different telescope designs next to each other with labels above them and a bullet list of points below the them. The left drawing will be described first then the right.]

:[Left:]
:<big>Refractor</big>

:[A slim telescope design is shown. At the top the light enters shown in a light yellow shade between two thin parallel light gray lines that just fits inside the opening of the telescope which is slightly wider at the top than at the lens sitting a short way into the opening. The lens causes the light to focus just where the telescope again changes dimensions, and the light enters a small opening at the bottom of the long pipe of the telescope. Here the yellow light is a point as the two gray lines cross each other at that point. The light then broadens slightly again and the thin yellow light cone hits a mirror at the bottom of the telescope and is reflected to the left and out through the eyepiece. Below are the following points:]
:*More expensive
:*Less compact
:*Chromatic aberration
:*Reduced light-gathering

:[Right]
:<big>Reflector</big>

:[A much broader (more than 150% of the first) but also much shorter (66%) telescope design is shown. At the top the light enters shown in a light yellow shade between two thin parallel light gray lines that still just fits inside the opening of the telescope. On it's way down to the bottom of the telescope the light passes by a small mirror turned down towards the bottom. When the hits the curved bottom mirror light is focus on it's way back back and a small light cone hits the small mirror mentioned before sitting almost at the top of the telescope. This mirror reflects the light to the left into an even thinner light cone that goes out through the eyepiece located near the top of the telescope. Below are the following point:]
:*Can't see space vampires

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Telescopes]]
[[Category:Rankings]]
[[Category:Science]]
[[Category:Astronomy]]
[[Category:Space]]
[[Category:Religion]]