explain xkcd - User contributions [en]

Talk:2849: Under the Stars

2023-11-02T09:12:07Z

172.71.242.140:

Reminds me a lot of many of Randall's first few dozen XKCD's that weren't trying to be funny but just kind of sweet and observational. [[User:Laser813|Laser813]] ([[User talk:Laser813|talk]]) 15:32, 1 November 2023 (UTC)
: "Mostly void, partially stars..." [[Special:Contributions/172.71.151.161|172.71.151.161]] 18:07, 1 November 2023 (UTC)

Is the title text trying to relate the black hole to the Star of Bethlehem? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 15:49, 1 November 2023 (UTC)
: No, he's just trying to make you freak out that a black hole is RIGHT ABOVE YOUR HEAD!!! ;) [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 16:31, 1 November 2023 (UTC)
:: Good thing I don't live in Los Angeles :) [[User:Certified_nqh|Me]][[[285: Wikipedian Protester|''citation needed'']]][[Category:Pages using the "citation needed" template]] 16:54, 1 November 2023 (UTC)
::: On the other hand, I live pretty damn near {{w|Atlanta}}, so it's pretty damn close to coming over my head every day... Edit: Just checked the zoomable map... it goes right over my head every day [[User:SomeoneIGuess|someone, i guess]]([[User talk:SomeoneIGuess|talk i guess]]|[[Special:Contributions/SomeoneIGuess|le edit list]]) 17:44, 1 November 2023 (UTC)
:::: Well, I'm 20ish° away from that track (and have never actually been anywhere near that latitude, despite occasional intercontinental travel). Looks like I'm not going to be in danger of hitting a black hole.... [[Special:Contributions/172.70.90.220|172.70.90.220]] 18:48, 1 November 2023 (UTC)

I think we need a category for "comics in full color" since there are 519 with color, but most of those aren't full color [[User:Laser813|Laser813]] ([[User talk:Laser813|talk]]) 18:25, 1 November 2023 (UTC)
: [[Technically]], it's not in full color, because Cueball and Megan's heads are white, not skin tone [[User:SomeoneIGuess|someone, i guess]]([[User talk:SomeoneIGuess|talk i guess]]|[[Special:Contributions/SomeoneIGuess|le edit list]]) 18:48, 1 November 2023 (UTC)
:: As I was thinking. But I was trying to think of a good word (like "photorealistic", though it isn't quite that) to describe significant arty/colourwashed scenic elements. There are a handful of comics (I think, without trawling through the candidates I have in mind, or look for others) that are so coloured. [[Special:Contributions/172.69.194.194|172.69.194.194]] 19:03, 1 November 2023 (UTC)
::Maybe that is their skin tone, though. skin colours in comic strip land don't necessarily correspond to those in human experience land. [[Special:Contributions/172.71.242.140|172.71.242.140]] 09:12, 2 November 2023 (UTC)

Is there something significant about V404-Cygni? Surely there are enough black holes that there's at least one that passes over every line of latitude. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 19:31, 1 November 2023 (UTC)
: My best guess: Randall picked it at random because it's funny. [[User:SomeoneIGuess|someone, i guess]]([[User talk:SomeoneIGuess|talk i guess]]|[[Special:Contributions/SomeoneIGuess|le edit list]]) 23:31, 1 November 2023 (UTC)
:: I'm thinking he chose it because of its number – V404. Isn't '404' the internet error code for something that can't be found... something that has figuratively slipped into a black hole somewhere? [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 07:29, 2 November 2023 (UTC)
:::As I recall, he previously quoted this particular black hole in a prior "passes directly over..." reference, which ''perhaps'' (I can't quite remember how, without searching) tied in with the requirements of that particular comic/article/whatif. And, at some point, you're gonna get yourself a 'favourite' that you'll reference whenever you get a decent chance, right? [[Special:Contributions/172.70.85.28|172.70.85.28]] 08:45, 2 November 2023 (UTC)
: To quote wikipedia: In 2009, the black hole in the V404 Cygni system became the first black hole to have an accurate parallax measurement for its distance from the Solar System. -- [[User:Hkmaly|Hkmosealy]] ([[User talk:Hkmaly|talk]]) 00:10, 2 November 2023 (UTC)
:The Earth wobbles quite a bit. How long will it be pointing close enough (I guess within 1 minute of declination) that V404-Cygni will be over that specific line of latitude? [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 02:30, 2 November 2023 (UTC)

2726: Methodology Trial

2023-01-23T13:02:57Z

172.71.242.140: /* Explanation */ Better in-line wikilinking.

{{comic
| number = 2726
| date = January 18, 2023
| title = Methodology Trial
| image = methodology_trial_2x.png
| imagesize = 339x459px
| noexpand = true
| titletext = If you think THAT'S unethical, you should see the stuff we approved via our Placebo IRB.
}}

==Explanation==
{{incomplete|Created by a PLACEBO RESEARCHER - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

When testing the efficacy of a potential medical treatment, researchers compare subjects who received the treatment against subjects who received a {{w|placebo}}. Usually each subject does not know whether they received the treatment or placebo, and neither do the practitioners, until the end of the trial. This distinguishes the actual effects of the treatment from the effects of simply participating in a study. People who receive a placebo (or an ineffective treatment) often believe their treatment is working due to such causes as paying more attention to one's health or expecting to feel better. This misattribution of effect to a non-treatment is called the "placebo effect".

In this comic a team of researchers appears to have studied some medical treatment, using a placebo controlled test. They present their findings in which a particular subset of participants (out of at least four distinct groups) shows an apparently significant result. The graph shows that three groupings have results whose error-bars indicate that they might easily have zero (or neutral) true effects, if not negative ones. But, even at the lowest extent of the accepted uncertainty, the fourth stands out as definitively having some degree of positive effect (of whatever kind this particular graph is plotting).

However, it is revealed that the 'treatment' they were given was also a placebo. Their own study was the subject of a placebo controlled test conducted on their methodology. They were the placebo group, while a different team presumably used the exact same methodology to study the real treatment. Thus, all of this team's findings were due to the placebo effect, or else the trial size and scope allowed a purely statistical 'blip' to occur, instead of there being any real merit to the "treatment". This indicates that their methodology shouldn't be used for any real world applications. This may be a subtle dig at the recent {{w|aducanumab}} Alzheimer's drug trial controversy, where post-hoc reanalysis of one subgroup of patients revealed a surprising result when the overall trial had otherwise failed.

The particular flaw in the methodology appears to be dividing too few subjects into too many sub-groups, allowing a chance cluster of anomalous results to overly influence an apparent result. The researcher did find significance in one sub-group, even though in reality there was no signal, just noise, since it was all placebo groups. This references the same p-hacking problem as [[882: Significant]]. Only in this case the researcher themself is the subject of the real trial.

If the non-placebo study had the exact same size and design (as it should have, in such a meta-study), it would cast doubt upon whether any similar-looking findings in London were significant. Especially if they also found that the same subgroup were again exhibiting the sole significant effect, which might reveal an inbuilt flaw in the procedure. On the other hand, it could just further show how likely any particular grouping was to falsely show a result; if all groups had apparently benefited, the chances are that most of them were correct, whether or not [[2268: Further Research is Needed]].

Treatments ''can'' be more effective on specific subgroups of the population; for example, an anti-cancer drug might only work against specific mutations that cause cancer. But any such result needs to have appropriate statistical significance and new subjects from that subgroup should be tested to ensure the result is repeated.

The title text points out how the experiment has almost certainly violated some set of ethical standards, because one researcher offers what he believes to be genuine treatment to a large number of participants only for a third party (the offscreen speaker) to replace all his medicine with placebos, ultimately deceiving the patients. The title text implies that it was approved by a genuine Institutional Review Board (IRB), the group which decides whether a proposed experiment is ethical to perform. However they also have a "placebo IRB", presumably made up of people who have no qualifications to make such judgements well, or perhaps not made up of people at all, but simply a mechanism for generating random decisions.

However, such a methodology trial using all placebos wouldn't necessarily be unethical. In addition to using a placebo, most studies are "double blind" meaning neither the patients nor the doctors/nurses treating them know who is getting the placebo and who is not; only the researchers conducting the study know. This is so doctors/nurses cannot inadvertently let the patients know who is getting real medicine (by acting with remorse around patients they know are not being treated, or being more cheerful with patients they know who are). It is considered perfectly ethical for doctors to give patients what they believe is medicine but is not (the placebo). This is because without the double blind procedure it may not be possible to identify real medicines from ones that have no effect, and the impact of preventing real medicine from being used by millions is greater than the deceit towards the small number receiving a placebo in the experiment. By extension it could be ethical to have the researcher conduct a trial with two placebos without knowing it. For instance if the London team and the team in the comic were finding beneficial effects in new drugs that other researchers found had no effect (or finding other drugs didn't work when others had evidence they did) then it may be worth investigating if their shared methodology has the flaw demonstrated in the article. That way regulatory agencies could exclude their flawed data when they make decisions on what drugs to approve, while the two teams could shift to a better methodology and return to contributing to medical science.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball stands in front of a poster holding a pointer. The poster shows a scatter plot with four points and error bars, with one data point labeled "Subgroup" is marked with an asterisk and is placed somewhat higher up than the other three points.]
:Cueball: However, we see clear evidence that the treatment is more effective than the placebo for some subgroups.
:Off-panel voice: Thank you.
:Off-panel voice: However, we can now reveal that the '''''London''''' team was studying the real treatment. Both groups in your study got a placebo.
:Cueball: Aw, '''''maaan...'''''
:[Caption below panel]
:Researchers hate it when you do placebo controlled trials of their methodology.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Scientific research]]

Facebook

2023-01-19T17:20:34Z

172.71.242.140: Undo revision 305021 by AshleeDescoteaux (talk) An undo I'm doing only 'cos theusafBOT has not...

#REDIRECT [[300: Facebook]]

2725: Sunspot Cycle

2023-01-17T16:00:37Z

172.71.242.140: /* Explanation */ tweaks

{{comic
| number = 2725
| date = January 16, 2023
| title = Sunspot Cycle
| image = sunspot_cycle_2x.png
| imagesize = 740x503px
| noexpand = true
| titletext = Who can forget the early 2010s memes? 'You know you're a 90s kid if you remember the feeling of warm sunlight on your face.' 'Only 90s kids remember the dawn.'
}}

==Explanation==
{{incomplete|Created by a NINETIES KID WHO FELT SUN - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic is a reference to the {{w|solar cycle}}, which is a roughly 11-year cycle of changes in the Sun's activity from a period of minimal levels of various related phenomena ({{w|sunspots}}, solar radiation, ejecta, and solar flares) to one of maximum activity in these areas. As the cycle continues, the Sun returns to minimal activity and starts over. Without actually studying the Sun, however, there is no discernable difference to our daily lives here on Earth, and studying the Sun in enough detail is difficult due to its intrinsic and eye-damaging brightness whenever viewed directly.

This comics makes a joke that when the absolute number of sunspots appears to decrease it is not because they disappear, but because they get so crowded that they begin to merge, and thus the number of individual spots decreases whereas the area of the sun covered by sunspots continues to increase to near total 'darkness'. This causes there to be a completely dark Sun after 11 years, at which point any new sunspots are ''bright'' patches, and the next 11-year cycle repeats the process but accumulating bright spots until eventually it is all bright once more, giving a total bright/dark cycle of 22 years.

The curve showing the number of differentiable sunspots in this 22 year cycle would follow the curves for two whole cycles of our normal Sun, as the number of distinct spots (of either kind) decreases down to practically just one Sun-enveloping spot. The change in brightness over the cycle, however, repeats only over the full 22 years, darkening and then being made to shine bright once more as the other type of spot appears and begins to dominate once more.

Below is a graph showing the number of sunspots as a function of time from around 1965 to 2025. Periods where the sun is dark are shown with black under the curve, and in transition periods with lines of darkness getting closer together on the way to 'fully' dark area plus vals of light reinserting themselves in the lightening part of the cycle. Also for clarity the troughs are labeled with the sun being bright or dark. It is always when there are few spots that the sun is either completely free from spots and thus bright, or completely covered and thus dark. The maxima are always during the height of the transition between the two extremes, with a wide swathe of the time around the minima being mostly light or mostly dark, alternating at around a decade of each predominating.

At times, this closely synchronises with the calendar decades. From this curve it can be seen that the Sun was bright in the nineties, but not in the dark eighties or the dark time from around 2001 to 2014. This fact is mentioned in the title text (see below). Similarly the seventies were mostly bright, after the largely dark sixties, the width of the transition periods covering the marked decade-defining years in slightly offset ways compared to the neighbouring ones. After the darkness began around 2000, the shift was such that it finally got bright again around 2014, with darkness returning around 2024. This is because of the sunspot cycles are 11 years (making the illumination cycle 22 years) and eventually it no longer credibly meshes with the arbitrary decadal cut-offs.

All this would obviously be catastrophic if it happened in our version of the universe, as during a dark phase unsufficient light would be coming from the Sun, and the Earth could freeze if all the energy from the Sun was reduced. If the spots only affect light in the visible spectrum, then Earth would not freeze but plants would have trouble with photosynthesis and other natural processes would be interrupted. In our universe sunspots cool the area of the Sun where they appear, relative to the rest of the surface (50-75% of the nearly 6000K 'norm'), but they are far from being actually dark; [https://image.gsfc.nasa.gov/poetry/workbook/sunspot.html NASA says] that each sunspot on its own would glow orange, brighter than the Moon is when it is full (with a typically bright Sun illuminating it). So even in a completely sunspot-covered Sun, the Sun would still be brighter than the Moon ought to be. It would be possible to see it (and see by it) even if the heat delivered were very low and even at noon it would seemn to be {{wiktionary|crepuscular}} by our normal expectations. See more in the title text explanation.

These problems are obviously not a serious threat in the reality of the comic, as the Sun is truly dark and yet people and natural systems have long survived these dark periods and adapted accordingly. This becomes clear in the title text where internet memes indicate that people lived fine through the dark periods, although they obviously did not 'properly' see the Sun, as kids, if they were born during the early start of a 'dark decade'.

The title text indicates the effect on internet memes that the special solar cycle has had. During the 2010s in our universe there were many '90s kid' memes. Those were also popular in this universe, but they reflect that the Earth had at that time been dark since the 2000s, and thus only those born in the 90s and before would remember dawn or the feeling of the warm sun on their faces.

This of course indicates that the Sun is actually dark and gives no warmth. Thus it is a mystery how life on Earth prevails, but given that there were kids from the 1990s that made memes twenty years after, life does work in this strange alternate universe.

==Transcript==
:[This comics shows two graphs, one also with several images of the Sun in different times in the solar cycle. The top graph is much larger than the bottom graph, and above them is a explanation of what the graphs shows:]
:Ever wonder why the sun disappears for about 10 years every other decade? This terrifying period of worldwide darkness is a natural consequence of the 11-year sunspot cycle:

:[A graph is shown with a label above the arrow on the Y-axis and a label written above the left part of the X-axis with an arrow pointing from it to the right (there is not arrow on the X-axis line). The graph shows a sine curve with a dashed line. It starts close to the bottom and then increases, then decreases before i finally slightly increases again. Above the dashed line are eight circles representing the sun with various levels of sunspots, with an arrow between each circle pointing to the next to the right. All circles are just above the dashed curve and the small arrows between them also follow the curvature of the line, so this string makes the same shape as the curve. along the eight representation of the sun there are five labels. The eight Suns will be described below with labels given when relevant.]
:Y-Axis: Sunspot number
:Y-Axis: Time

:[The first Sun's circle is completely white]

:[The second Sun's circle has a few sunspots. A label is written to the left of it:]
:Dark sunspots appear

:[The third Sun's circle has several sunspots. A label is written to the left of it:]
:Sunspot number rises

:[The fourth Sun's circle is half covered in sunspots.]

:[The fifth Sun's circle is mostly black with a few lines of white dots. Between the fourth and fifth circle is a label:]
:Number falls as sunspots merge.

:[The sixth Sun's circle is almost completely black with just a few small white spots. A label is written above it:]
:Sunspots envelop sun, Earth enters years of darkness.

:[The seventh Sun's circle is mostly black with a few light areas.]

:[The eighth Sun's circle is still mostly black but with some larger white areas. A label is written above and left of it:]
:Bright sunspots appear, cycle reverses.

:[Below is a second graph with a label written near the top of the Y-axis which is otherwise not labeled. The X-axis also has no label, but six years are written beneath at equal intervals. The graph shows a similar sine curve as the one above, but with almost five cycles shown. Also each cycle is not close to being a perfect sine curve, but has the property with a peak followed by a trough. The five troughs are labeled. The area beneath the curve alternates from being black and white when there is a trough, with the peak in between having several vertical lines, indicating transfer from black to white and vise versa. There are not same distance between peaks and there are also features on the graphs, for instance the two peaks in the middle has a drop, so they look like volcanoes. And the last full peak has a clear outlier year with many sunspots.]
:Label: History:
:X-axis labels: 1970 1980 1990 2000 2010 2020
:Through 1970-1980: Sun is bright
:Through 1980-1990: Sun is dark
:Through 1990-2000: Sun is bright
:Through 2000-2010: Sun is dark
:Through 2010-2020: Sun is bright

{{comic discussion}}

[[Category:Astronomy]]
[[Category:Timelines]]
[[Category:Line graphs]]
[[Category:Internet]]

2725: Sunspot Cycle

2023-01-17T10:33:53Z

172.71.242.140: /* Explanation */ Skipped the erroneous "2000's". And correcting the comma/Citation Needed order. (Two CNs in one article looks too many, but not sure which I would excise.)

User talk:ColorfulGalaxy

2023-01-12T23:26:21Z

172.71.242.140: /* This is probably the first numbered comic whose title... */ ...missed an apostrophe.

==12==
Hi, what happens in [https://www.explainxkcd.com/wiki/index.php?title=User:ColorfulGalaxy&curid=25508&diff=301086&oldid=292141 12 edits]? Have a life-changing day in a good way! —[[User:While False|While False]] ([[User:While False/explain xkcd museum|'''museum''']] | [[User talk:While False|talk]] | [[special:Contributions/While_False|contributions]] | [[special:Log/While_False|logs]] | [[Special:UserRights/While_False|rights]] | [https://www.explainxkcd.com/wiki/index.php?title=User:While_False&printable=yes printable version] | [https://www.explainxkcd.com/wiki/index.php?title=User:While_False&action=info page information] | [https://www.explainxkcd.com/wiki/index.php/Special:WhatLinksHere/User:While_False what links there] | [https://www.explainxkcd.com/wiki/index.php?title=Special:RecentChangesLinked&days=30&from=&target=User%3AWhile_False related changes] | [https://www.google.com Google search] | current time: {{CURRENTTIME}}) 21:56, 11 December 2022 (UTC)

: I meant that I need 12 more edits to get [[explain_xkcd:Autoconfirmed_users|autoconfirmed]] so I can create more pages in my user page. The computer that I'm using runs awfully slow. My other computer blocks CAPTCHA automatically. [[User:ColorfulGalaxy|ColorfulGalaxy]] ([[User talk:ColorfulGalaxy|talk]]) 07:51, 13 December 2022 (UTC)

::Cool —[[User:While False|While False]] ([[User:While False/explain xkcd museum|'''museum''']] | [[User talk:While False|talk]] | [[special:Contributions/While_False|contributions]] | [[special:Log/While_False|logs]] | [[Special:UserRights/While_False|rights]] | [https://www.explainxkcd.com/wiki/index.php?title=User:While_False&printable=yes printable version] | [https://www.explainxkcd.com/wiki/index.php?title=User:While_False&action=info page information] | [https://www.explainxkcd.com/wiki/index.php/Special:WhatLinksHere/User:While_False what links there] | [https://www.explainxkcd.com/wiki/index.php?title=Special:RecentChangesLinked&days=30&from=&target=User%3AWhile_False related changes] | [https://www.google.com Google search] | current time: {{CURRENTTIME}}) 07:58, 13 December 2022 (UTC)

::: I just made it! Thanks for confirming my account! Now I can stop using that slow computer. --[[User:ColorfulGalaxy|ColorfulGalaxy]] ([[User talk:ColorfulGalaxy|talk]]) 09:08, 13 December 2022 (UTC)

== Google search link ==

A couple of times, recently, you provided a Google search link to something. I don't like following those (with their "q=..." stuff and hangover metadata in other POST data) when you could perhaps give the direct link you intend instead?

i.e. right-clicking on the Google page's item and copying that link is wasteful (and not ''always'' correct), you should instead follow the link you intend and then copy the true address (if proven to be what you wish) from the address-bar. And, even then, best to cut away any "&referer=..." type stuff (and restest the cut down link!) so that everyone who follows you has a bare-bones link that works without having to mess with reconstructing the metadata that means "<nowiki>http://whatever.com/foo/bar/baz.html#indexpoint</nowiki>", or howsoever it should resolve.

Just a tip. To streamline and not unneccessarily obfuscate the use of your contributions... [[Special:Contributions/172.70.91.77|172.70.91.77]] 15:15, 15 December 2022 (UTC)

== This is probably the first numbered comic whose title... ==

''Probably'' you could just confirm these claims, ''before'' making them? It seems easy enough to do, and you seem to have the time to do it. [[Special:Contributions/172.71.242.141|172.71.242.141]] 23:25, 12 January 2023 (UTC)

Talk:1882: Color Models

2023-01-07T16:08:56Z

172.71.242.140: Possibly over-the-top counterponderings...

For those who want to know a bit more about color, [https://www.handprint.com/LS/CVS/color.html this site] is a good start. [[User:Zmatt|Zmatt]] ([[User talk:Zmatt|talk]]) 15:08, 28 August 2017 (UTC)

This comic shows the trend of having a simple and satisfactory explanation for something, and the exasperation with repeatedly realizing the inadequacy of the explanation, making revisions, and having a more complex yet still inadequate model.

As Randall began his schooling, he learned that mixing the primary colours of pigment (red, blue, and yellow) together he could create almost any colour, so colour must be a combination of those 3 colours.

He also learned about rainbows, and that the colours in the rainbow were just different wavelengths of light. Somehow these different wavelengths created unique colours.

As Randall got older, philosophy and a discussion on perception came into play, and Randall came to the realization that his experiences are analogous to but not necessarily the same as his peers.

As he got older, Randall learned about colour spaces as used in pigments, light, and printing, possibly from computer science (Red, Green, Blue; Red, Yellow, Blue; Cyan, Magenta, Yellow, Key) as well as the physics of electromagnetic rays and the biology of vision, understanding that visible light is a small portion of the electromagnetic spectrum - one crudely interpreted by the 3 types of cones in our eyeballs.

Randall then learned about the opponent process model, wherein the signal from cones are not interpreted individually, but in difference to one another. "Responses to one color of an opponent channel are antagonistic to those to the other color. That is, opposite opponent colors are never perceived together – there is no "greenish red" or "yellowish blue"." (from wikipedia)

After that, Randall comes to understand the modeling of colour spaces and the design and limits of human visual perception - despite only having three cones, color space cannot be made into a triangle and still cover the gamut of human colour experience.

Klein manifolds are beyond me, you'll have to fill in something about that.

Eventually, the modeling becomes so complex (and yet still unsatisfactory) that Randall hopes it becomes someone else's problem. [[Special:Contributions/108.162.238.5|108.162.238.5]] 15:50, 28 August 2017 (UTC)MagnusVortex

I'm familiar with klein manifolds, they're peculiar 4D dimensional topological objects related to mobius strips. I have no Idea how they might relate to color, and doing a search for "a hyperdimensional four-sided quantum Klein manifold" returned pictures of bicycles...

It might be good to point out in the explaination that he progresses from a dual nature of color (light, and paint) at the beginning and then trends to a unified explaination of color. [[Special:Contributions/172.68.142.179|172.68.142.179]] 18:27, 28 August 2017 (UTC) Sam

: Yes those are great looking bikes and are called Klein Quantum racing bikes... so Google did its job of keyword matching. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 20:40, 28 August 2017 (UTC)

;The beauty of explainxkcd
The explanation of this comment is a great example of why this site is delightful — and nigh-invaluable! Thanks, regulars, for doing the work to help us understand all this.{{unsigned ip|108.162.246.101}}

----

Text explanation

I think the explanation of the text is missing an important point. It starts like it's about the philosophal question of "the same color for everybody", but ends with a very mundane explanation, which I think quite funny.

[[Special:Contributions/141.101.69.9|141.101.69.9]] 21:18, 28 August 2017 (UTC) Loïc

Yes, the description needs to include the fact that the top reference to color being unknowable is a reference to [https://en.wikipedia.org/wiki/Qualia qualia]. The brain of one individual may interpret colors differently than the brain of another individual, but since we would all use the same words for our interpretations of the same wavelengths, we can't really know if how I see blue is the same as how you see blue, hence that reference. But then in the tag, he has swapped out the reason for our different interpretations for the same color, blaming our browsers instead of our brains.

[[User:DarkJMKnight|DarkJMKnight]] ([[User talk:DarkJMKnight|talk]]) 11:14, 29 August 2017 (UTC)

Exactly this. Although really that only relates to our experience of colour, so I'm not sure how much relevance it has to the colour mixing track, despite the arrow. [[Special:Contributions/141.101.98.106|141.101.98.106]] 13:11, 29 August 2017 (UTC)

I added a comment about qualia, which could probably be improved upon. --[[Special:Contributions/172.68.47.66|172.68.47.66]] 14:52, 30 August 2017 (UTC)

----

"As the 4th dimension is time, the color space would probably change all the time."

...no. No. I'm removing that. Just... no.

[[User:Hakr14|Hakr14]] ([[User talk:Hakr14|talk]]) 23:03, 28 August 2017 (UTC)
:Just to explain to the people that aren't engineers, physicists, or mathematicians; while "the three dimensions" are commonly thought of as height/width/depth, with time often used as the 4th dimension, there is nothing that requires "dimensions" to refer to those properties. For example: a flat plane with a temperature distribution could be said to have three dimensions (height/width/temperature), or a cube could be said to have four (height/width/depth/temperature)[[Special:Contributions/108.162.237.100|108.162.237.100]] 17:00, 6 September 2017 (UTC)
::Much better in this context: Red/Green/Blue (RGB) is known by everybody as the basis to represent color mixtures, the fourth dimension is simply the brightness. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:37, 9 September 2017 (UTC)

Isn't the title text a reference to [https://bugs.chromium.org/p/chromium/issues/detail?id=44872 that pretty old Chromium bug]? [[Special:Contributions/162.158.22.4|162.158.22.4]] 13:53, 29 August 2017 (UTC)

I don't think Randall even scratched the surface. Ask "What is Yellow?"...it's the almost pure frequency of light given off by a sodium lamp at 589nm wavelength. Then, take a digital photo of a sodium lamp and look at the picture on an LED monitor. The color looks the same...but now you're looking at a mixture of red and green LED's - so you're seeing two frequencies at 660nm and 530nm...there is no yellow light. So, you ask yourself - is it the case that mixing two frequencies that the eye can see creates the illusion of a colour between the two?

Well, what color do you see when you mix red and blue? Magenta...right? But what color is midway between red and blue? That's Green. So the difference between Magenta and Green *should* be about the same as the difference between "Sodium lamp yellow" and "Picture of sodium lamp yellow".

The Mantis Shrimp can see 12 'primary colors' and is sensitive to the plane of polarization of the light. We see 3 primaries and have no clue about polarization.

: That's not true. We can see Haidinger's Brush. See https://en.wikipedia.org/wiki/Haidinger%27s_brush . [[Special:Contributions/198.41.238.34|198.41.238.34]] 10:09, 30 August 2017 (UTC)

Humans are all essentially color blind.
[[User:SteveBaker|SteveBaker]] ([[User talk:SteveBaker|talk]]) 16:55, 29 August 2017 (UTC)

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There is no mention of the RGB/RYB/CYMK issue in the explenation [[Special:Contributions/162.158.111.211|162.158.111.211]] 06:13, 30 August 2017 (UTC)

What if, what you see as blue when you look at the sky in real life, I see as a slightly different blue, because the different web browsers we've been using have retrained our eyes to perceive meatspace differently? [[User:Promethean|Promethean]] ([[User talk:Promethean|talk]]) 20:57, 2 September 2017 (UTC)

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For what it's worth, the most natural way to describe color exactly is as an infinite-dimensional Hilbert space. Each pure frequency is a dimension, so a color is a vector with |R|-many elements, each representing the intensity of a different frequency. The inner product induces a norm that represents the brightness of the color. The sensitivities of the cone cells are basically encoded in the definition of the inner product.
[[Special:Contributions/108.162.237.59|108.162.237.59]] 20:01, 26 August 2022 (UTC)

:Depends on what you mean by ''color''. I don't think eyes (or digital sensors) can perceive an '''infinite''' range of frequencies. Referring to high-energy gamma rays as "colors" and then trying to distinguish between colors based on their energy difference would be to distort the meaning of the term. Same for radio at the other end. Even in the visual range, can the eye distinguish between 660nm and 660.1nm light? I very much doubt it. In any practical sense, then, there are not "infinite" colors. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 12:52, 7 January 2023 (UTC)

::I'm not sure what the qualification is for "colour", but if it's based upon a particular sensing creature/aparatus, then there is a degree of finiteness tied to how many chromatic detection ranges it employs (and the response curve each is informed by, and then further by the perception resolution of the near neighbouring frequencies). It could be quite tight, and it would be fully calculable if it involved digital encoding (less sure in analogue scenarios and, e.g., human vision is tricksy... as can be seen in the {{w|Checker shadow illusion}}, and similar) so properly finite. Even for a given {{w|Hyperspectral imaging|hyperspectral camera}}.
::But if you want to cover [i]any[/i] observation(/-device) that can be made then you're effectively unbounded by the possibilities of 'spectral resolution'. Can your eye differentiate between 660nm and 660.1nm? Probably not. But you cannot say that no eye does (and we can and do build sensors that would do so).
::Possibly physical laws intervene at one point though. Effectively a "Planck spectral-separation", as the limited number of elements compounded into a (very large but still finite...ish) number of receptive materials, setting an upper bound of direct response to bits of any spectra. Or, if prism-split and projected, the limit to which the resulting smear of rainbow light can be spread out and then having the limit of assessing a thin enough wedge of it. But, with always the possibility of finding a trick to go beyond the current level chromatic differentiation (applying an oscillating reflector, LIGO-like, to alternate the very slightest red-/blue-shifts back and forth across the existing threshold in a detectable way?), its as near as dammit an infinitely detailed continuum, probably even beyond what useful detail might be usefully presented by the otherwise sane bit of the universe that is blithely transmitting whatever light we are so interested in receiving for analysis. [[Special:Contributions/172.71.242.140|172.71.242.140]] 16:08, 7 January 2023 (UTC)