explain xkcd - User contributions [en]

3015: D&D Combinatorics

2024-11-23T02:51:13Z

108.162.216.214: /* Transcript */

{{comic
| number = 3015
| date = November 22, 2024
| title = D&D Combinatorics
| image = dnd_combinatorics_2x.png
| imagesize = 328x446px
| noexpand = true
| titletext = Look, you can't complain about this after giving us so many scenarios involving N locked chests and M unlabeled keys.
}}

==Explanation==
{{incomplete|Created by a BOT THAT GRABBED A CURSED ARROW - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

Dungeons and Dragons (D&D) is a role-playing game that usually has a "Dungeon Master" (narrator) that takes a team of players through scenarios where they attack monsters and go on quests.

Often, there will be semi-random events: e.g., when attacking a monster, often, a player would roll a die and deal damage based on what that die returns. D&D also uses a variety of dice, from regular d6 (6-sided, cubic dice) to other polyhedral dice, with the number of faces denoted by dX (e.g., d10 is a 10-sided die, with numbers from 1 to 10 on it). Common sets include: d4, d6, d8, d10, d12, d20, and occasionally d100 (typically not, however, the [[2626:_d65536|d65536]]).

With these, you can simulate events with a wide variety of denominators. In this case, Cueball gives a combinatorial problem:

* There are 10 arrows.
* 5 arrows are cursed.
* You randomly take two.
* What are the odds that neither of them are cursed?

There are: "10 choose 2" (45) ways to choose two arrows, of which there are "5 choose 2" (10) ways to choose 2 arrows that are non-cursed. As a result, the odds of taking all non-cursed arrows is 2/9.

The Dungeon Master in this case has to map that probability into rolling multiple dice, whose sums are also not evenly distributed: i.e. if rolling 3D6 (3 six-sided dice) and a D4 (1 four-sided die), the sums can range from 4 to 22. It's pretty hard to do this in one's head, but it does happen that the odds of rolling 16 or more with this combination is 2/9, matching the probability that we want to simulate.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball, Megan, Ponytail, White Hat, and Knit Cap are sitting at a table. Everyone is looking at Cueball. Ponytail is facepalming. The table is covered in sheets of paper and assorted dice.] 
:Cueball: I grab 2 of the 10 arrows without looking and fire them, hoping I didn't grab one of the 5 cursed ones. Did I?
:Ponytail: Sigh. Umm. Okay.
:Ponytail: Roll... Uh... Hang on...
:Ponytail: Roll 3d6 and a d4. You need... 16 or better to avoid the cursed arrows.

:[Caption below the panel:]
:I got '''''way''''' more annoying to play D&D with once I learned that our DM has a combinatorics degree and can't resist puzzles.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Knit Cap]]
[[Category:Games]]
[[Category:Math]]

3015: D&D Combinatorics

2024-11-23T02:48:46Z

108.162.216.214: /* Transcript */

Talk:2398: Vaccine Tracker

2020-12-16T23:45:36Z

108.162.216.214:

🎵 A B C D E F G H I've got a cure! 🎶
[[Special:Contributions/162.158.74.85|162.158.74.85]] 02:53, 15 December 2020 (UTC)
:...In Kalamazoo-zoo-zoo-zoo-zoo! [[Special:Contributions/108.162.216.214|108.162.216.214]] 23:45, 16 December 2020 (UTC)
Maybe he needs a [[2382: Ballot Tracker Tracker|vaccine tracker tracker]] [[Special:Contributions/162.158.78.40|162.158.78.40]] 03:24, 15 December 2020 (UTC)
:And if that goes missing, a vaccine tracker tracker finder? Then a—[[952: Stud Finder|shut up]].
:Or a [[2376: Curbside|vaccine tracker tracker]], but then if he loses it [[1504: Opportunity|AAAAAAAAAAAAAAAAA]] and that transmission, at 05:52, 15 December 2020 (UTC) was the last we ever heard from Sonata. [[User:Bubblegum|bubblegum]]-[[User_talk:Bubblegum|talk]]|[[Special:Contributions/Bubblegum|contribs]]

And this on a day when I was mindlessly updating the pointless Electoral College votes just to double check that there were no faithless voters throwing the thing into more confusion. And I am not even American. Iam in priority group eight. My wife is in group nine - but might be in group eight before they get to her. The only things I know about kalamazoo are payroll and guitars - but I believe one is long superceded and the other left. [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]]) 12:29, 15 December 2020 (UTC)

Just learnt that Kalamazoo Payroll is owned by Dominion, the plot deepens. They were not corrupting the election, they were messing with the vaccine trackers. [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]]) 12:31, 15 December 2020 (UTC)

:What, they are owned by {{w|Dominion (Star Trek)|Dominion}}? Does Tal Shiar already know that? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 00:11, 16 December 2020 (UTC)

"*refresh* Aww, still in Kalamazoo, *refresh* Yay, 'A connection could no..' .. oh." [[User:Ocæon|ocæon]] ([[User talk:Ocæon|talk]]) 13:25, 15 December 2020 (UTC)

I knew my choice to live in Kalamazoo would be validated eventually. [[Special:Contributions/162.158.74.31|162.158.74.31]] 14:49, 15 December 2020 (UTC)

I nearly put that Cueball should just get on with his attenuated life while he waits for the attenuated vaccine, but that only describes some of the possible candidates he could (eventually) be given, so isn't a brilliant pun... Also, I did computer training (Novell server administration, to be precise) at Kalamazoo, but I have no idea why they called the company that (no geographic connection, and the song lyrics I know from the Goon Show half-time version seem hardly linkable at all) and I think they went bust/changed name again not long after I 'graduated'. [[Special:Contributions/162.158.155.78|162.158.155.78]] 21:22, 15 December 2020 (UTC)

2394: Contiguous 41 States

2020-12-04T23:54:58Z

108.162.216.214: transcript

{{comic
| number = 2394
| date = December 5, 2020
| title = Contiguous 41 States
| image = contiguous_41_states.png
| titletext = Linguists, settling some inscrutable grudge, have been steadily sneaking more backdated synonyms for 'sharing borders' into the dictionary. They've added 'contiguous,' 'coterminous,' 'conterminous,' and next year they're adding 'conterguous.'
}}

==Explanation==
{{incomplete|Created by a BOT. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

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

The Contiguous 41 States

[A map of the United States, missing Delaware, Kansas, New Mexico, Nebraska, North Dakota, Pennsylvania, and South Dakota, along with Alaska and Hawaii]

Tired of being left off maps of the US, Alaska and Hawaii begin producing maps with ''other'' states missing, too.

{{comic discussion}}

Talk:529: Sledding Discussion

2018-02-01T15:44:51Z

108.162.216.214: /* pancakes or waffles? */ new section

I am convinced there is also a subtle reference to one of Calvin's gags, regarding a toboggan's "model year". I'm a little too lazy to delve back into an archives site and cite it though, so have fun looking for it! Anonymous 04:06, 4 December 2013 (UTC)

I believe that the initial conversation of the loss of language opportunity refers to a theory in Language Acquisition called Critical Period Hypothesis[http://en.wikipedia.org/wiki/Critical_period_hypothesis]. [[Special:Contributions/108.162.216.32|108.162.216.32]] 23:47, 6 September 2014 (UTC)

If it wasn't for the titletext I would've thought Megan to be referring to the lost freedom of being a single. Only after that I understood the "failed metaphor" part. [[Special:Contributions/162.158.90.212|162.158.90.212]]

Except it's not closed to you. Plenty of people learn languages later in life that they end up being completely fluent in. [[User:Benjaminikuta|Benjaminikuta]] ([[User talk:Benjaminikuta|talk]]) 03:50, 26 March 2016 (UTC)

== pancakes or waffles? ==

Tell me what you think.

1862: Particle Properties

2017-07-12T17:39:17Z

108.162.216.214: explained alignment (and then there was a merge conflict)

{{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 (maxmium 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 sugests, but after failing to provide a good indication of {{w|Flavour (particle physics)|flavor}}, quickly devolves to other domains, such as role playing games (such as D&D) and sports.

{| class=wikitable
! Property
! Scale
! Explanation
|-
| Electric charge
| [-1,1]
| A particle can either have a negative charge (noted by -1), a positive charge (noted by +1), or no (neutral) charge (noted by 0). Subatomic particles (quarks) have charges of ± ⅓ or ± ⅔, but cannot exist on their own (they must be combined to create a particle with integer charge).
The charge is shown in increments of a third from -1 to +1 which are the only know charges of the fundamental particles; however there are some exotic particles with twice integer charge e.g. the recently discovered double charmed Xi baryon with charge of +2.
|-
| Mass
| [0,∞) in kg
| Mass is the measure of an object or particle's resistance to force, as well as its ability to distort 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.
|-
| Spin number
| (-∞,∞) (Intervals of ½)
| Spin is an intrinsic properties of particles, Spin is 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, this is 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 identical fermions (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 axis
|-
| Color charge
| 3D 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.
|-
| 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
|
|-
| Batting average
| [0,100) in %
| In baseball, a players batting average is calculated by dividing their hits by their at-bats.
|-
| Proof
| [0,200)
| This refers to {{w|alcohol proof}}, which is the measure of the amount of ethanol in a beverage by volume. The proof of a beverage is two times the percentage of ethanol, so the maximum value is 200.
|-
| Heat
| No jalapeños - 3 jalapeños, 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]]

1824: Identification Chart

2017-04-14T13:36:58Z

108.162.216.214: Added some background related to the origin of charts like this.

{{comic
| number = 1824
| date = April 14, 2017
| title = Identification Chart
| image = identification_chart.png
| titletext = Be careful-it's breeding season, and some of these can be *extremely* defensive of their nests.
}}

==Explanation==
{{incomplete|Created by a BOT - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
General military training often includes aircraft identification. [http://en.wikipedia.org/wiki/Aircraft_recognition Silhouette charts] are given to ground observers for memorization and reference so that friend or foe can be determined in the field.
Some aircraft are named after animals, including {{w|bird of prey|birds of prey}}, other birds, and insects. This comic presents an "identification guide" of silhouettes, each with the {{w|fuselage}} of an aircraft and the wings of the flying animal from which the aircraft gets its name. All are birds with the exception of the {{w|hornet|hornet}} which is an insect. This would be absurd if it was a plane with the feathers designed, as bird wings are usually made to support the lightweight structure of a bird and supporting the parts of a plane with its human pilot would be impossible.{{Citation needed}} Alternatively, it could hint at a universe where the air force uses cyborg flying animals.

The comic highlights not only the various designs of aircraft tails, but also bird wings. Some wings are highly adapted for soaring (eagle), speed (falcon), as well as rapid acceleration and short flights (blackbird).

{| class="wikitable"
!Name
!Plane
!Explain
|-
|{{w|Osprey|Osprey}}
|{{w|Bell_Boeing_V-22_Osprey|V-22 Osprey}}
|The tilt-rotor V-22 Osprey has been in development since the 1980s, and was introduced to the U.S. Armed Forces in 2007.
|-
|{{w|Hornet|Hornet}}
|{{w|McDonnell_Douglas_F/A-18_Hornet|F/A-18 Hornet}}
|A design stemming from the 1970s, the U.S. Navy now flies an updated and larger version, the F-18E/F.
|-
|{{w|Falcon|Falcon}}
|{{w|General_Dynamics_F-16_Fighting_Falcon|F-16 Falcon}}
|A smaller, more versatile fighter jet. Has been sold to many foreign air forces.
|-
|{{w|Harrier|Harrier}}
|{{w|Harrier_Jump_Jet|AV-8B Harrier}}
|The first operational STOL/VTOL fighter. They are known for their use in the Falklands War (1982), where they operated from converted cargo ships as well as aircraft carriers.
|-
|{{w|Eagle|Eagle}}
|{{w|McDonnell_Douglas_F-15_Eagle|F-15 Eagle}}
|Introduced in 1976, other jets like F-16 have filled its role. The U.S. Air National Guard is the largest operator as of now.
|-
|{{w|Kestrel|Kestrel}}
|{{w|Kestrel_K-350|Kestrel_K-350}}
|The Kestrel is a single-engine, proof-of-concept aircraft, similar to the {{w|Pilatus PC-12}}.
|-
|{{w|Hawk|Hawk}}
|{{w|BAE_Systems_Hawk|Hawk T1}}
|A trainer aircraft. {{w|T-45 Goshawk}} is the U.S. designation of a variant of this aircraft. The fuselage silhouette is of a BAe Hawk, although other aircraft have also had Hawk-related names, for example the Hawker [https://en.wikipedia.org/wiki/Hawker_Sea_Hawk Sea Hawk] and the Douglas [https://en.wikipedia.org/wiki/Douglas_A-4_Skyhawk A-4 Skyhawk]
|-
|{{w|Blackbird|Blackbird}}
|{{w|Lockheed_SR-71_Blackbird|SR-71 Blackbird}}
|A Mach 3+ spy aircraft, known for its speed and engine concept (which works both as a turbine and a ramjet).
|}

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

{{comic discussion}}

54: Science

2017-01-27T23:53:39Z

108.162.216.214: Fixed syntax error to wiki page

{{comic
| number = 54
| date = January 18, 2006
| title = Science
| image = science.jpg
| titletext = Bonus points if you can identify the science in question
}}

==Explanation==
The solid line represents the theoretical {{w|blackbody radiation|radiation for a blackbody}} at 2.73 K according to {{w|Planck's Law}} (derived as early as 1900 by {{w|Max Planck}}). The formula, almost as written in the graph, can be found {{w|Black-body radiation#Planck's law of black-body radiation|here}}. The only changes are that on Wikipedia, the frequency f is represented by the Greek letter ν (nu) and the temperature T is included as an independent variable, so I(f) becomes I(v,T). However, I(v,T) still represents the {{w|Radiance#Spectral radiance|spectral radiance}} (similar to energy density). In this formula, h is the Planck constant, c is the speed of light in a vacuum and k is the Boltzmann constant. The frequency (f or v) along the X-axis is measured in {{w|GHz}} (Giga (or billion) Herz). The curve peaks at 160.4 GHz. There is no scale or unit on the {{w|energy density}} on the Y-axis.

The theory is that the blackbody in question was in fact the universe at the point when it had cooled down enough {{w|Decoupling (cosmology)|to allow photons to escape}}, {{w|Chronology of the universe|0.38 million years}} into the universe's {{w|Big Bang|13.8 billion years}} history. The photons that reach us today are the ones that have been travelling to us at lightspeed since then. As the light from astronomical objects suffers from {{w|redshift}} due to the expansion of the universe, and this shift becomes more pronounced with distance from the observer, this light displays in the infrared range.

The title text praises viewers who can identify where this equation and corresponding graph come from (without consulting this wiki, of course).

===Official T-shirt explanation===
This comic was made into a T-shirt.

On the xkcd store there is both an '''explanation for the title:'''

Science: We finally figured out that you could separate fact from superstition by a completely radical method: observation. You can try things, measure them, and see how they work! {{w|Bitch (insult)|Bitches}}.


And specifically an '''explanation for the graph:'''

The graph on the back of the shirt is data from the{{w|COBE|COBE mission}} which looked at the background microwave glow of the universe and found that it fit perfectly with the idea that the universe used to be really hot everywhere. This strongly reinforced the Big Bang theory and was one of the most dramatic examples of an experiment agreeing with a theory in history -- the data points fit perfectly, with error bars too small to draw on the graph. It's one of the most triumphant scientific results in history.


The above is a direct copy paste, with errors. The current wiki page of the COBE mission can be found at {{w|Cosmic Background Explorer|http://en.wikipedia.org/wiki/Cosmic_Background_Explorer}}

This comic is available on a T-shirt from the [http://store-xkcd-com.myshopify.com/products/science-works xkcd stores].

==Transcript==
:[A graph with a curve that begins at zero, then peaks at a given frequency, indicated via a thin vertical line, and then fades down towards zero. It is possible to see the data point, which the curve fits perfectly. The Y-axis is labeled. Along the X-axis the zero point and the frequency where the peak has its maximum are labeled and close to the arrow the unit of this axis is written.]
:Y-axis: Energy Density
:Along the X-axis:
::0
::160.4
::GHz
:[Above the graph to the right is the following formula, with the last inner parentheses only included to make the formula clear, since in the drawing the fractions are written above and below horizontal lines:]
:I(f) = (2hf3/c2)(1/(ehf/kT-1))
:[Below the graph is written the following:]
:'''Science.'''
:It works, bitches.

==Trivia==
*This was the 48th comic originally posted to [[LiveJournal]].
**The previous was [[50: Penny Arcade]].
**The next was [[51: Malaria]].
*This comic kept its original title: "Science"
**It is part of the last six comics on LiveJournal which all had a title without the word "Drawing" in it.
**Five of these had exactly the same title on both sites.
**Only 11 comics have the same title on both sites.
**Apart from the [[:Category:First day on LiveJournal|thirteen first comics]] posted to LiveJournal, there were only three other comics without the word "Drawing" in the title before these last six.
*Original [[Randall]] quote: "Bonus points if you can identify the science in question."
**Only difference between this and the title text on xkcd is the last period: "."
**It was rare that these two texts were so similar.
*This comic was one of the last 11 comics posted on LiveJournal.
**These 11 comics were [[:Category:Posted on LiveJournal after xkcd|posted both on LiveJournal and xkcd]] after the [[xkcd]] site opened on the 1st of January 2006.
**The first six comics were posted on both sites on the same day. But not this one.
*For some reason this comic was first posted a week later on xkcd (25 January 2006), on the day that [[53: Hobby]] was released on LiveJournal.
**On the day 54: Science was released on LiveJournal (18 January 2006), another comic ([[51: Malaria]]) was released on xkcd.
**[[51: Malaria]] also became the next comic released on LiveJournal, but this meant that three comics in a row were posted a release day earlier on xkcd than on LiveJournal.
**Only with the last comic released on LiveJournal, [[55: Useless]], did the two sites release the same comic on the same day again.

{{comic discussion}}

[[Category:Comics posted on livejournal| 48]]
[[Category:Posted on LiveJournal after xkcd]]
[[Category:Line graphs]]
[[Category:Math]]
[[Category:Physics]]
[[Category:Science]]

54: Science

2017-01-27T23:52:23Z

108.162.216.214: Added reference to supporting Wiki page

{{comic
| number = 54
| date = January 18, 2006
| title = Science
| image = science.jpg
| titletext = Bonus points if you can identify the science in question
}}

==Explanation==
The solid line represents the theoretical {{w|blackbody radiation|radiation for a blackbody}} at 2.73 K according to {{w|Planck's Law}} (derived as early as 1900 by {{w|Max Planck}}). The formula, almost as written in the graph, can be found {{w|Black-body radiation#Planck's law of black-body radiation|here}}. The only changes are that on Wikipedia, the frequency f is represented by the Greek letter ν (nu) and the temperature T is included as an independent variable, so I(f) becomes I(v,T). However, I(v,T) still represents the {{w|Radiance#Spectral radiance|spectral radiance}} (similar to energy density). In this formula, h is the Planck constant, c is the speed of light in a vacuum and k is the Boltzmann constant. The frequency (f or v) along the X-axis is measured in {{w|GHz}} (Giga (or billion) Herz). The curve peaks at 160.4 GHz. There is no scale or unit on the {{w|energy density}} on the Y-axis.

The theory is that the blackbody in question was in fact the universe at the point when it had cooled down enough {{w|Decoupling (cosmology)|to allow photons to escape}}, {{w|Chronology of the universe|0.38 million years into the universe's {{w|Big Bang|13.8 billion years}} history. The photons that reach us today are the ones that have been travelling to us at lightspeed since then. As the light from astronomical objects suffers from {{w|redshift}} due to the expansion of the universe, and this shift becomes more pronounced with distance from the observer, this light displays in the infrared range.

The title text praises viewers who can identify where this equation and corresponding graph come from (without consulting this wiki, of course).

===Official T-shirt explanation===
This comic was made into a T-shirt.

On the xkcd store there is both an '''explanation for the title:'''

Science: We finally figured out that you could separate fact from superstition by a completely radical method: observation. You can try things, measure them, and see how they work! {{w|Bitch (insult)|Bitches}}.


And specifically an '''explanation for the graph:'''

The graph on the back of the shirt is data from the{{w|COBE|COBE mission}} which looked at the background microwave glow of the universe and found that it fit perfectly with the idea that the universe used to be really hot everywhere. This strongly reinforced the Big Bang theory and was one of the most dramatic examples of an experiment agreeing with a theory in history -- the data points fit perfectly, with error bars too small to draw on the graph. It's one of the most triumphant scientific results in history.


The above is a direct copy paste, with errors. The current wiki page of the COBE mission can be found at {{w|Cosmic Background Explorer|http://en.wikipedia.org/wiki/Cosmic_Background_Explorer}}

This comic is available on a T-shirt from the [http://store-xkcd-com.myshopify.com/products/science-works xkcd stores].

==Transcript==
:[A graph with a curve that begins at zero, then peaks at a given frequency, indicated via a thin vertical line, and then fades down towards zero. It is possible to see the data point, which the curve fits perfectly. The Y-axis is labeled. Along the X-axis the zero point and the frequency where the peak has its maximum are labeled and close to the arrow the unit of this axis is written.]
:Y-axis: Energy Density
:Along the X-axis:
::0
::160.4
::GHz
:[Above the graph to the right is the following formula, with the last inner parentheses only included to make the formula clear, since in the drawing the fractions are written above and below horizontal lines:]
:I(f) = (2hf3/c2)(1/(ehf/kT-1))
:[Below the graph is written the following:]
:'''Science.'''
:It works, bitches.

==Trivia==
*This was the 48th comic originally posted to [[LiveJournal]].
**The previous was [[50: Penny Arcade]].
**The next was [[51: Malaria]].
*This comic kept its original title: "Science"
**It is part of the last six comics on LiveJournal which all had a title without the word "Drawing" in it.
**Five of these had exactly the same title on both sites.
**Only 11 comics have the same title on both sites.
**Apart from the [[:Category:First day on LiveJournal|thirteen first comics]] posted to LiveJournal, there were only three other comics without the word "Drawing" in the title before these last six.
*Original [[Randall]] quote: "Bonus points if you can identify the science in question."
**Only difference between this and the title text on xkcd is the last period: "."
**It was rare that these two texts were so similar.
*This comic was one of the last 11 comics posted on LiveJournal.
**These 11 comics were [[:Category:Posted on LiveJournal after xkcd|posted both on LiveJournal and xkcd]] after the [[xkcd]] site opened on the 1st of January 2006.
**The first six comics were posted on both sites on the same day. But not this one.
*For some reason this comic was first posted a week later on xkcd (25 January 2006), on the day that [[53: Hobby]] was released on LiveJournal.
**On the day 54: Science was released on LiveJournal (18 January 2006), another comic ([[51: Malaria]]) was released on xkcd.
**[[51: Malaria]] also became the next comic released on LiveJournal, but this meant that three comics in a row were posted a release day earlier on xkcd than on LiveJournal.
**Only with the last comic released on LiveJournal, [[55: Useless]], did the two sites release the same comic on the same day again.

{{comic discussion}}

[[Category:Comics posted on livejournal| 48]]
[[Category:Posted on LiveJournal after xkcd]]
[[Category:Line graphs]]
[[Category:Math]]
[[Category:Physics]]
[[Category:Science]]

54: Science

2017-01-27T23:49:47Z

108.162.216.214: Corrected 0.38 BILLION with 0.38 MILLION YEARS, per https://en.wikipedia.org/wiki/Chronology_of_the_universe

{{comic
| number = 54
| date = January 18, 2006
| title = Science
| image = science.jpg
| titletext = Bonus points if you can identify the science in question
}}

==Explanation==
The solid line represents the theoretical {{w|blackbody radiation|radiation for a blackbody}} at 2.73 K according to {{w|Planck's Law}} (derived as early as 1900 by {{w|Max Planck}}). The formula, almost as written in the graph, can be found {{w|Black-body radiation#Planck's law of black-body radiation|here}}. The only changes are that on Wikipedia, the frequency f is represented by the Greek letter ν (nu) and the temperature T is included as an independent variable, so I(f) becomes I(v,T). However, I(v,T) still represents the {{w|Radiance#Spectral radiance|spectral radiance}} (similar to energy density). In this formula, h is the Planck constant, c is the speed of light in a vacuum and k is the Boltzmann constant. The frequency (f or v) along the X-axis is measured in {{w|GHz}} (Giga (or billion) Herz). The curve peaks at 160.4 GHz. There is no scale or unit on the {{w|energy density}} on the Y-axis.

The theory is that the blackbody in question was in fact the universe at the point when it had cooled down enough {{w|Decoupling (cosmology)|to allow photons to escape}}, 0.38 million years into the universe's {{w|Big Bang|13.8 billion years}} history. The photons that reach us today are the ones that have been travelling to us at lightspeed since then. As the light from astronomical objects suffers from {{w|redshift}} due to the expansion of the universe, and this shift becomes more pronounced with distance from the observer, this light displays in the infrared range.

The title text praises viewers who can identify where this equation and corresponding graph come from (without consulting this wiki, of course).

===Official T-shirt explanation===
This comic was made into a T-shirt.

On the xkcd store there is both an '''explanation for the title:'''

Science: We finally figured out that you could separate fact from superstition by a completely radical method: observation. You can try things, measure them, and see how they work! {{w|Bitch (insult)|Bitches}}.


And specifically an '''explanation for the graph:'''

The graph on the back of the shirt is data from the{{w|COBE|COBE mission}} which looked at the background microwave glow of the universe and found that it fit perfectly with the idea that the universe used to be really hot everywhere. This strongly reinforced the Big Bang theory and was one of the most dramatic examples of an experiment agreeing with a theory in history -- the data points fit perfectly, with error bars too small to draw on the graph. It's one of the most triumphant scientific results in history.


The above is a direct copy paste, with errors. The current wiki page of the COBE mission can be found at {{w|Cosmic Background Explorer|http://en.wikipedia.org/wiki/Cosmic_Background_Explorer}}

This comic is available on a T-shirt from the [http://store-xkcd-com.myshopify.com/products/science-works xkcd stores].

==Transcript==
:[A graph with a curve that begins at zero, then peaks at a given frequency, indicated via a thin vertical line, and then fades down towards zero. It is possible to see the data point, which the curve fits perfectly. The Y-axis is labeled. Along the X-axis the zero point and the frequency where the peak has its maximum are labeled and close to the arrow the unit of this axis is written.]
:Y-axis: Energy Density
:Along the X-axis:
::0
::160.4
::GHz
:[Above the graph to the right is the following formula, with the last inner parentheses only included to make the formula clear, since in the drawing the fractions are written above and below horizontal lines:]
:I(f) = (2hf3/c2)(1/(ehf/kT-1))
:[Below the graph is written the following:]
:'''Science.'''
:It works, bitches.

==Trivia==
*This was the 48th comic originally posted to [[LiveJournal]].
**The previous was [[50: Penny Arcade]].
**The next was [[51: Malaria]].
*This comic kept its original title: "Science"
**It is part of the last six comics on LiveJournal which all had a title without the word "Drawing" in it.
**Five of these had exactly the same title on both sites.
**Only 11 comics have the same title on both sites.
**Apart from the [[:Category:First day on LiveJournal|thirteen first comics]] posted to LiveJournal, there were only three other comics without the word "Drawing" in the title before these last six.
*Original [[Randall]] quote: "Bonus points if you can identify the science in question."
**Only difference between this and the title text on xkcd is the last period: "."
**It was rare that these two texts were so similar.
*This comic was one of the last 11 comics posted on LiveJournal.
**These 11 comics were [[:Category:Posted on LiveJournal after xkcd|posted both on LiveJournal and xkcd]] after the [[xkcd]] site opened on the 1st of January 2006.
**The first six comics were posted on both sites on the same day. But not this one.
*For some reason this comic was first posted a week later on xkcd (25 January 2006), on the day that [[53: Hobby]] was released on LiveJournal.
**On the day 54: Science was released on LiveJournal (18 January 2006), another comic ([[51: Malaria]]) was released on xkcd.
**[[51: Malaria]] also became the next comic released on LiveJournal, but this meant that three comics in a row were posted a release day earlier on xkcd than on LiveJournal.
**Only with the last comic released on LiveJournal, [[55: Useless]], did the two sites release the same comic on the same day again.

{{comic discussion}}

[[Category:Comics posted on livejournal| 48]]
[[Category:Posted on LiveJournal after xkcd]]
[[Category:Line graphs]]
[[Category:Math]]
[[Category:Physics]]
[[Category:Science]]

Talk:1776: Reindeer

2016-12-23T14:32:50Z

108.162.216.214: CAPTCHA works for me

Captcha does not work on mobile browser. (Android Firefox) Had to switch over to laptop to make edit. Also, it's two words, not one as the thing above implies ("To help protect against automated edit spam, please type the word you see in the box below:") ~Dartania [[Special:Contributions/162.158.74.141|162.158.74.141]] 14:03, 23 December 2016 (UTC)

: This post was made with Firefox on Android. Are you sure you didn’t just get a difficult CAPTCHA? [[Special:Contributions/108.162.216.214|108.162.216.214]] 14:32, 23 December 2016 (UTC)