explain xkcd - User contributions [en]

Talk:1683: Digital Data

2021-06-09T05:08:44Z

108.162.249.18:

Ewww, Verizon? **** them [[User:International Space Station|International Space Station]] ([[User talk:International Space Station|talk]]) 04:58, 20 May 2016 (UTC)
::Don't forget the whole "Verizon Math" incident and Randall's much passed around check image. I'd be surprised if it isn't on 9GAG somewhere.... [[User:Psu256|Psu256]] ([[User talk:Psu256|talk]]) 17:12, 23 May 2016 (UTC)
:: https://xkcd.com/verizon/ [[Special:Contributions/198.41.238.16|198.41.238.16]] 02:30, 15 July 2017 (UTC)

Ironically, the title text on explainxkcd is different from the one on xkcd.com, demonstrating the reinterpretation of text encoded in UTF-8 as if it were encoded in ISO 8859-1. [[Special:Contributions/162.158.85.231|162.158.85.231]] 05:45, 20 May 2016 (UTC)

-Exactly; this nicely proves Randall's point. On my computer, different characters appear in different browsers, but of course in one browser the characters are reproducible.--[[User:Jkrstrt|Jkrstrt]] ([[User talk:Jkrstrt|talk]]) 07:26, 20 May 2016 (UTC)

Here is the decoded title text:
“If you can read this, congratulations–the archive youʼre you're using still knows about the mouseover text”!
[[Special:Contributions/108.162.229.16|108.162.229.16]] 07:51, 20 May 2016 (UTC)

:Grungy details:
:*â€œ -> ''convert to hex'' -> E2-80-9C -> ''UTF8 decode'' -> 0010-000000-011100 -> [http://www.fileformat.info/info/unicode/char/201C/index.htm U-201C "LEFT DOUBLE QUOTATION MARK"]
:*â€” -> ''convert to hex'' -> E2-80-94 -> ''UTF8 decode'' -> 0010-000000-010100 -> [http://www.fileformat.info/info/unicode/char/2014/index.htm U-2014 "EM DASH"]
:*â€™ -> ''convert to hex'' -> E2-80-99 -> ''UTF8 decode'' -> 0010-000000-011001 -> [http://www.fileformat.info/info/unicode/char/2019/index.htm U-2019 "RIGHT SINGLE QUOTATION MARK"]
:*â€! -> ''convert to hex'' -> E2-80-9D -> ''UTF8 decode'' -> 0010-000000-011101 -> [http://www.fileformat.info/info/unicode/char/201d/index.htm U-201D "RIGHT DOUBLE QUOTATION MARK"]
:[[User:Odysseus654|Odysseus654]] ([[User talk:Odysseus654|talk]]) 17:31, 20 May 2016 (UTC)

::The ''convert to hex'' step is really ''encode with Windows-1252''. Also, in the last sequence, the "!" is not part of the encoded quotation mark. The third byte of the quotation mark comes from an unprintable U-009D between the "â€" and the "!". U-009D isn't a valid Windows-1252 character, so either the encoding is actually a superset of Windows-1252 that includes U-009D, or the encoding process just allowed it.
:: [[Special:Contributions/162.158.255.103|162.158.255.103]] 17:26, 21 May 2016 (UTC)

He's written you're twice, but one is with a curly apostrophe, often favoured by americans (and maybe brits?), possible because of their keyboard. The simple apostrophe is “just” html-formatted, whereas the curly one has been molested by a UTF-8 / ISO-8859-1 misreading.
--[[Special:Contributions/108.162.229.16|108.162.229.16]] 07:51, 20 May 2016 (UTC)
: I'm British, and I don't have the curly apostrophe anywhere on my keyboard. [[User:Enchantedsleeper|Enchantedsleeper]] ([[User talk:Enchantedsleeper|talk]]) 11:01, 20 May 2016 (UTC)

: I'm American, and I also don't have the curly apostrophe anywhere on my keyboard, but word processing programs (like MS-Word) are configured by default to automatically replace an ASCII apostrophe in a conjunction with the fancy right-single-quote mark. Also when using quotation marks around text those programs automatically replace the repeated single ASCII quotation marks with the fancy left and right quotation marks (single if using single quotes, double if using double quotes). Most people don't care enough to disable that "feature"... [[Special:Contributions/162.158.252.143|162.158.252.143]] 15:13, 20 May 2016 (UTC)

:: Ok. I've never experienced that from any text processor (incl. MS Word), so maybe it's dependant on the system locale or another mysterious factor. I've just noticed a prevalence in english language texts online, but an absence in other european languages. Not even french, which has as many or more contractions. [[Special:Contributions/108.162.229.16|108.162.229.16]] 08:11 21 May 2016 (UTC)

This is a phenomenon that has always both fascinated me and frustrated me. I find it fascinating how, even today, data degrades as more and more people copy it (remember the old days when people used to copy VHS tapes, and the further you were from the original tape the more copying artefacts your copy had in it?). It also frustrates me, though, when I'm trying to find an original, undegraded image or video and it seems impossible to find. It's also annoying because it's actually pretty easy to copy something without causing any quality loss, yet practically every copied image on the internet has been degraded in some way or another. [[Special:Contributions/141.101.98.130|141.101.98.130]] 07:08, 20 May 2016 (UTC)

:If you haven't yet, you should check out this guy who ripped and reuploaded his own Youtube video 1000 times: https://www.youtube.com/watch?v=jEIzS_27Vt0 [[Special:Contributions/162.158.222.150|162.158.222.150]] 08:28, 20 May 2016 (UTC)

::...and after 100 iterations https://www.youtube.com/watch?v=k6GMvihskBQ ...and the summary of all of them https://www.youtube.com/watch?v=icruGcSsPp0 [[User:Odysseus654|Odysseus654]] ([[User talk:Odysseus654|talk]]) 16:50, 20 May 2016 (UTC)

:It can be frustrating to try to convince new people drawing schematics on the computer to not use 4-way junctions because they don't expect digital images to degrade over multiple generations of copying. This xkcd demonstrates the way multiple generations can degrade even digital images, potentially making it difficult to differentiate two crossing (but electrically separate) signal lines from a 4-way junction on a schematic. Sorry, I'll get off my soap box now. ;-) [[Special:Contributions/162.158.252.143|162.158.252.143]] 15:13, 20 May 2016 (UTC)

It's also funny because just a few moments ago I was trying to compress some video to send to someone. [[Special:Contributions/141.101.98.130|141.101.98.130]] 07:12, 20 May 2016 (UTC)

http://fotoforensics.com/analysis.php?id=274fcf46426f2da31b057f1652ae5269cfdbd70a.190103 this page highlights the encoding blocks so that the degration of quality can be seen better. [[Special:Contributions/141.101.91.205|141.101.91.205]] 09:42, 20 May 2016 (UTC)

:Nice example. Their picture is already a bad copy. While it's still a PNG, it's already reduced in size (600x228 instead of 720x282, 131381 byte instead of 190103). Btw. the file used in this wiki is also slightly different from what I see on xkcd. It's just 3 minutes older and 308 bytes larger. [[Special:Contributions/162.158.83.48|162.158.83.48]] 01:28, 23 May 2016 (UTC)

The phenomenon that Randall is making fun of in this comic is actually called a "shitpic" http://www.theawl.com/2014/12/the-triumphant-rise-of-the-shitpic The explanation should probably make reference to that. [[User:Enchantedsleeper|Enchantedsleeper]] ([[User talk:Enchantedsleeper|talk]]) 10:57, 20 May 2016 (UTC)

I think the watermarks on the last frame are from an unregistered screenshot tool, not "9gag" or similar. The references to shit pics are interesting, but aren't you over interpreting the whole thing? {{unsigned ip|162.158.83.174}}
: ...You realise that over-interpreting is what this wiki is ''for'', right? Also, not really, since all I said was that a "shitpic" is what this type of degraded image is called. [[User:Enchantedsleeper|Enchantedsleeper]] ([[User talk:Enchantedsleeper|talk]]) 15:03, 23 May 2016 (UTC)

There's a 9gag thing in the image, clean your glasses and look again. --[[Special:Contributions/173.245.54.46|173.245.54.46]] 12:15, 20 May 2016 (UTC)

Both screenshots from iOS definitely. Safari browser and… anybody knows? Some kind of other web browser? Maybe Chrome or Opera? <Need to finally create account> [[Special:Contributions/162.158.202.152|162.158.202.152]] 15:32, 20 May 2016 (UTC)

Apparently Russians have been getting this a lot, as they (up to the point of the existence of UNICODE) have had to deal a lot with people using bad codepages. Example of their post office dealing with a physical package addressed with a bad codepage: http://worldlanguages.wikia.com/wiki/Mojibake?file=Letter_to_Russia_with_krokozyabry.jpg [[User:Odysseus654|Odysseus654]] ([[User talk:Odysseus654|talk]]) 16:54, 20 May 2016 (UTC)

Here is the progression as I see it:
*Frame 1 - The original PNG
*Frame 2 - The PNG converted to a JPEG
*Frame 3 - The JPEG as viewed on a mobile browser (Safari on iOS in this case)
*Frame 4 - A screen-shot of the mobile browser uploaded to Tumblr and then stolen by 9GAG
[[Special:Contributions/173.245.52.62|173.245.52.62]] 19:37, 20 May 2016 (UTC)

Note that while the term "digital" is new, first digital format of information appeared long ago, with the development of standard alphabet. Images hand-drawn on paper can't be copied without loss, but if you write letters in fixed alphabet, it can be copied without errors forever (not counting errors caused by some letters getting out of use through history). Egyptian literature is probably lost due to us not knowing the (very big) full set of hieroglyphs, but [https://el.wikisource.org/wiki/%CE%9F%CE%B4%CF%8D%CF%83%CF%83%CE%B5%CE%B9%CE%B1/%CE%B1 Odyssey] could (and hopefully even was) be stored exactly how it was written. Wouldn't help read it, of course, language changed since then and it would need to be translated which, again, can lose some meaning ... -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 16:16, 21 May 2016 (UTC)

There's a much much older example. RNA and subsequently DNA are digital representations of the protein structures (also digital representations of 3-D molecular shapes). Degradation through copying is 1 source of variation which evolution selects over.[[User:MerlinMM|MerlinMM]] ([[User talk:MerlinMM|talk]]) 11:28, 23 May 2016 (UTC)
:Right. Humans were using digital data for their own reproduction long before they knew what "digital", "data" or even just "letter" is. DNA even uses primitive error correction techniques. Although when humans finally found out about RNA being digital, they already had other digital formats. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 00:21, 15 July 2017 (UTC)
::There's nothing primitive at all about DNA error correction techniques, just some people's understanding of them. [[Special:Contributions/198.41.238.16|198.41.238.16]] 02:35, 15 July 2017 (UTC)

Is it possible that the watermark in the bottom left of the last panel is supposed to read "drama.tumblr.com"?
--[[Special:Contributions/173.245.52.67|173.245.52.67]] 20:42, 23 May 2016 (UTC)

The alt text has been fixed, the second "You're" has been removed. {{unsigned ip|141.101.104.80}}

The phenomenon is related to {{w|Generation loss}} --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 14:50, 27 May 2016 (UTC)

Btw, does anybody know a digital archive that actually "knows about the title-text"? {{unsigned ip|162.158.17.66}}

;Source image updating?

If you look at the comic on the website, the first couple of frames are much more "decayed" than they are on the wiki copy. --[[Special:Contributions/198.41.238.16|198.41.238.16]] 01:47, 19 December 2016 (UTC)
: The source image has definitely been changed. [http:////imgs.xkcd.com/comics/digital_data.png Here's] the original image, and [http:////imgs.xkcd.com/comics/digital_data_2x.png here's] the new one. --[[Special:Contributions/162.158.59.190|162.158.59.190]] 01:13, 23 December 2016 (UTC)
:: Ok, this is weird - earlier today (2018-12-21), I was seeing the low-res version. But this evening, I'm seeing the high-res version. In between, I had linked it from reddit, maybe it switches based on popularity? [[Special:Contributions/172.68.132.95|172.68.132.95]] 07:23, 22 December 2018 (UTC)
:::I don't think so? I just saw the original comic after it was linked from reddit, still the degraded version. It was actually how I found about the degrading image. [[User:Herobrine|Herobrine]] ([[User talk:Herobrine|talk]]) 11:58, 13 March 2019 (UTC)
::::Getting worser [[Special:Contributions/172.69.69.196|172.69.69.196]] 04:49, 13 April 2019 (UTC)
::::As briefly described in the explanation, the high-DPI version of the comic is actually worse than the low-DPI version. Since comic [[1084]], xkcd offers higher-quality images if you're viewing it on a high-DPI screen - a tablet, a smartphone, or a high resolution PC or laptop. In a normal comic, the high-DPI image (twice the width and twice the height in pixels) would be sharper and nicer to look at on such a screen. In this comic, however, randall has deliberately made it ''worse'' than the low-DPI image. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 12:08, 25 December 2020 (UTC)

Ironically, the special characters across xkcd.com appear to be messed up in a the same way the title text of this comic references--including the title text of this comic itself. It now reads, "Ã¢â‚¬Å“If you can read this, congratulationsÃ¢â‚¬â€the archive youÃ¢â‚¬â„¢re using still knows about the mouseover textÃ¢â‚¬Â!"
[[Special:Contributions/162.158.63.124|162.158.63.124]] 01:25, 12 October 2019 (UTC)
: That happens if the page defaults to "Western" encoding. Switch it to UTF-8 and it changes back to the original 'failure'. --[[User:Aaron of Mpls|Aaron of Mpls]] ([[User talk:Aaron of Mpls|talk]]) 05:45, 11 February 2020 (UTC)

It is 2019. Disney+ has launched. It cropped 19 seasons of Simpsons from 4:3 to 16:9, by just getting rid of the top and bottom of the images. It is the official streaming version of the series. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 10:36, 18 November 2019 (UTC)

My laptop shows the 2x image instead of the normal image on this comic. Has it been replaced or does my laptop just use the 2x images for some reason?
[[Special:Contributions/162.158.79.19|162.158.79.19]] 23:26, 25 February 2021 (UTC)

Talk:1683: Digital Data

2021-06-09T05:06:59Z

108.162.249.18:

2469: Astronomy Status Board

2021-06-04T22:09:46Z

108.162.249.18: /* Explanation */ next hundred years -> life of the status board - directly link to the absurdity of using the status board

{{comic
| number = 2469
| date = May 28, 2021
| title = Astronomy Status Board
| image = astronomy_status_board.png
| titletext = Junior astronomers hate getting put on board update duty, but someone's gotta make sure that stuff is still up there.
}}

==Explanation==
[[Ponytail]] is staring at the sky through a telescope while [[Cueball]] is operating a checklist, visible on a large screen on what looks like a large billboard.

Since they are junior astronomers, they appear to have been tasked with simply verifying whether normal celestial objects are still present in the sky, such as the Sun and the Moon. Only large objects that are clear in the sky (at least at night for those not the Sun). Although all of these objects will eventually disappear it is not expected to happen within the life of the status board. {{Citation needed}}

This is likely a reference to the many "status boards" for online services ([https://portal.office.com/ServiceStatus example], [https://status.cloud.google.com/ another example], [https://forum.suprbay.org/status a different example], [http://hasthelargehadroncolliderdestroyedtheworldyet.com/ a funnier example]). The joke is that it would be funny if there was a status board to check that all the celestial bodies are still there, and that with our modern culture few people are looking directly at the real sky, even though anyone with a telescope and an unobstructed view could just look at the sky to verify for themselves without referencing such a status board. This is compounded by the fact that the listed celestial bodies have existed for billions of years, and are expected to last for billions more, leading one to wonder why astronomers would bother checking and rechecking just to see if they're "still there" with any sort of regularity.

This comic may also be an oblique reference to the study of the projected future of celestial objects given our current understanding of physics. At various points in the future the objects on the billboard may become unobservable from Earth. The Moon is gradually receding from Earth, and when the Sun enters its red giant phase the Moon might be broken up.[https://www.space.com/3373-earth-moon-destined-disintegrate.html] Eventually the Sun itself will run out of {{w|Sun#After_core_hydrogen_exhaustion|usable fuel}} and will go dark as will other stars. Moreover, if current theories of dark energy and universal expansion hold, the acceleration of the universe could push galaxies beyond the {{w|Cosmological_horizon#Hubble_horizon|"Hubble Horizon"}}, meaning they would no longer be observable. Matter itself could even cease to exist under some hypothetical scenarios, such as {{w|Proton_decay|proton decay}} or the {{w|Big_Rip|Big Rip}}. The joke of the comic here would be that all these scenarios are only possible in the unimaginably far future (exception: {{w|False_vacuum_decay|False Vacuum Decay}} ) and do not need constant monitoring by astronomers.

==Transcript==
:[Ponytail is looking through a telescope, while Cueball is pressing buttons, which makes noises, on a remote control connected with a wire to a large board to their right. He controls the messages shown on this board.]
:Remote: Beep beep

:[The board has a black screen, with a label in a white section above the screen:]
:Astronomy Status Board:

:[The black screen has five rows with text in three columns. The first column is with white text. The second is in glowing green text and the last are in faded grey red text.]
Moon '''Still there''' Gone
Sun '''Still there''' Gone
Stars '''Still there''' Gone
Planets '''Still there''' Gone
Galaxies '''Still there''' Gone

==Conditions under which celestial objects might be considered "gone"==
Astronomers do regularly observe {{w|occultation}}s of stars by other celestial bodies, and sometimes also search through archived images for missed occultations. This can provide information on the size and orbit of an asteroid too small to observe directly, or other useful scientific knowledge, but occulted stars are not "gone", merely hidden. There are also a few astronomers who are searching image archives for [https://www.space.com/hunt-for-universe-missing-stars-space-mysteries stars that really have completely vanished without a trace] (or suddenly appeared), as this would be a sign of truly novel physics -- perhaps even a sign of extraterrestrial intelligence -- but no such vanishings have yet been identified. This comic appeared at the time the [https://vasconsite.wordpress.com/ VASCO project] is receiving media attention, claiming that [https://iopscience.iop.org/article/10.3847/1538-3881/ab570f 800 stars visible in 70 years old photos are not seen anymore].

Small stars which have exhausted their hydrogen fuel without building enough heat to fuse carbon or oxygen, are theorized to eventually collapse into faint "{{w|white dwarf}} stars" which are of such low luminosity that they are unlikely to remain visible to the naked eye from the Earth's surface except at very close proximities. The Earth's sun, Sol, is generally expected to follow this progression as a low-mass {{w|main sequence}} star, during the latter period of its {{w|stellar evolution}}. Although some stellar models predict that relatively rapid collapses are possible, the long time scale over which stellar evolutions are believed to occur decreases the odds of observing any one specific star both before and after this transition. In this comic, individual stars are not listed; therefore "gone" is unlikely to be useful for the stars, because a great number of stars would be "still there" until well after the expected collapse of our own sun.

One of the proposed outcomes of the ultimate fate of the universe is the {{w|Big Rip}}. If it's correct, all the items on the status board will eventually move from Still There to Gone, beginning with the most distant galaxies and proceeding to the the objects in our own solar system (although there will be hardly any time for the board to show Gone for the closest, especially the Moon). This scenario is dramatized in the short story "{{w|Last Contact}}" by Stephen Baxter.

Collisions between celestial bodies are commonly postulated as a fundamental part of the formation of {{w|planetary nebula}}. Since most mass in the known universe is observed to have a relatively low {{w|albedo}}, the presence of numerous unlit, massy bodies of planetary scale and smaller is strongly indicated. This is corroborated by measurements of orbital deflection detected in many visible stars, hinting at the possibility of large planets orbiting around them, unseen due to distance & low luminosity. The possibility of one or more local planets being "gone" could be attributed to unpredicted collision with another object of similar mass or equivalent velocity. Such a collision is one possible explanation for the sudden & catastrophic disintegration of Earth's moon, Luna, in the novel {{w|Seveneves}} by Neal Stephenson. This hypothetical event forms the premise of this book, during which Earth's whole sky becomes occluded by dust raised by millions of impacts across its surface & eventually by the constant incandescent descent of lunar debris itself. Again however, a single collision with any planet besides the Earth would not remove ''all'' the "Planets" from the Earth's visible night sky, so "gone" remains unlikely to be used for that category of celestial objects.

Occlusion of Earth's entire sky, due to airborne dust, volcanic ash, increased cloud cover, {{w|light pollution}}, or sufficiently dense layers of high-albedo material in orbit, may be the least unlikely potential reason for all of these celestial phenomena to be flagged as "gone". Notably, the phenomena in question would remain; only our view of them would be gone.

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Astronomy]]
[[Category:Comics with color]]

1179: ISO 8601

2021-05-19T00:37:23Z

108.162.249.18: /* Explanation */ Citation needed - as evidence that the format referred to is never used

{{comic
| number = 1179
| date = February 27, 2013
| title = ISO 8601
| image = iso_8601.png
| titletext = ISO 8601 was published on 06/05/88 and most recently amended on 12/01/04.
}}

==Explanation==
When abbreviating the date into numerical form, {{w|Date format by country|various areas of the world}} tend to list the year, month, and day in different orders (as well as with different delimiting symbols), which can cause confusion particularly when the day value is 12 or lower allowing it to be easily interpreted as the month and vice versa. As a {{w|public service announcement}}, this comic states that there is in fact one international standard for writing numeric dates, set by the {{w|International Organization for Standardization}} in its {{w|ISO 8601}} standard: YYYY-MM-DD.

The comic then proceeds to list several discouraged ways of writing out the date of the comic's publication, as they do not match the standard. It begins with several commonly used ones in countries around the world, but then begins to list increasingly uncommon ways, ranging from strange (Roman numerals) to quirky (binary, Unix time) to essentially impossible (painting the numbers onto a black cat).

The title text provides a perfect example of the kind of ambiguity that can arise when non-standard formats are used. The ISO standard was in fact published on 1988-06-05 and amended on 2004-12-01. This is mentioned in the title text in MM/DD/YY format; however, there is no way to naturally figure this out, particularly with the second date. With the year truncated to two digits and all three numbers at 12 or lower, the date referring to December 1, 2004 may well be interpreted as 12 January 2004, or as 2012-01-04.

Date formats were again the subject in [[1340: Unique Date]].

The other mentioned formats are:

{| class=wikitable
! Date !! Explanation
|-
| 02/27/2013
| MM/DD/YYYY, used mostly in the United States.
|-
| 02/27/13
| MM/DD/YY, same as above but with the year shortened to two digits.
|-
| 27/02/2013
| DD/MM/YYYY, used variously in South America, Canada ({{w|Date_and_time_notation_in_Canada|officially uses ISO 8601}}), Australia, New Zealand and Europe.
|-
| 27/02/13
| DD/MM/YY, same as above but with the year shortened to two digits.
|-
| 20130227
| YYYYMMDD, same as ISO 8601 without delimiting punctuation. Allowed by the standard. Technically not ambiguous but is hard to read as a date at first glance.
|-
| 2013.02.27
| YYYY.MM.DD, used in Japan, South Korea and Hungary. Same as ISO 8601 except with different punctuation.
|-
| 27.02.13
| DD.MM.YY, used in Germany, Russia, and others.
|-
| 27-02-13
| DD-MM-YY, used in Denmark, Netherlands, Indonesia, India, Bangladesh, and others.
|-
| 27.2.13
| D.M.YY. It is common in several areas to abbreviate the month or day to a single digit and drop the leading zero when possible.
|-
| 2013. II. 27.
| YYYY. MM. DD., with month as {{w|Roman numerals}}, used in Hungary.
|-
| 27⁄2-13
| D⁄M-YY, traditional format in Denmark, Norway and Sweden
|-
| 2013.158904109
| Year and decimal fraction of year. 0.158904109 is a decimal approximation of 58/365, with February 27 being the 58th day of the year. This format may be easier to read for computers/programs in some contexts, but is difficult for humans to interpret.
|-
| MMXIII-II-XXVII
| The ISO 8601 standard but written in Roman numerals. Never used as a traditional standard anywhere as it is hard to read, parse, and interpret for no benefit.
|-
| MMXIII LVII⁄CCCLXV
| Year followed by its partial fraction 57/365, all in Roman numerals. Equally useless as the above. As a note, apparently this 'standard' is different from the decimal fraction two rows above, as the decimal fraction notation uses the ''end'' of the day (first day of the year is 1/365 while the last is 365/365), while this uses the ''beginning'' (first day is 0/365 and last is 364/365).
|-
| 1330300800
| {{w|Unix time|UNIX Timestamp}}, a standard method of storing absolute time in many computer systems and defined as the number of seconds since 00:00:00 on 1970-01-01 (UTC). The Unix time listed here appears to mistakenly be for '''2012'''-02-27, which is also mentioned by [[Randall]] in the original transcript. The Unix Timestamp for 2013-02-27 would be 1361923200.
|-
| ((3+3)×(111+1)-1)×3/3-1/33
| A useless format where the numbers 2013, 2, and 27 written as needlessly long arithmetic expressions using just the digits 1 and 3. For additional confusion, the values are delimited by slashes, enabling confusion with the fraction bar. (If evaluated literally, the entire expression evaluates to 670.963, or 671 minus 1 divided by 27.)
|-
|    2  272013
| A nearly impossible to read date "format" that can be considered a parody "compromise" between different formats: rather than argue about the order in which the year, month, and day should be, they are simply all written on top of each other. As a "bonus", there is also no arguing over which separator character to use.
|-
| 10/11011/1101
| The US mm/dd/yy format in {{w|Binary number|binary}}, corresponding to 2/27/13. Never used for obvious reasons.
|-
| 02/27/20/13
| MM/DD/CC/YY, where CC stands for century. This format is never used{{Citation needed}}. Note that while months and days count starting from 1, centuries and years in this format count from 0 for extra confusion. But the CC value is widely used on many operating systems to distinguish between the 20th and 21st century, represented by the values "19" and "20" because 1950 belongs to the 20th century.
|-
| <ruby><rb>0</rb><rb>1</rb><rb>2</rb><rb>3</rb><rb>7</rb><rt>2</rt><rt>3</rt><rt>1</rt><rt>4</rt><rtc style="ruby-position: under"><rt>5</rt><rt></rt><rt>67</rt><rt></rt><rt>8</rt></rtc></ruby>
| An obfuscated format where the small numbers indicate the positions where the large digits should be placed. In this reading, 0 is used at positions 2 and 5, 1 is used on position 3, etc.; the result being 20130227
|-
| [A hissing black cat with "2-27-13" painted on it]
| In Western cultures, black cats and the number 13 are associated with bad luck. The cat might also just be angry that someone covered it in paint.
|}

==Transcript==
:Public Service Announcement:

:Our different ways of writing dates as numbers can lead to online confusion. That's why in 1988 ISO set a global standard numeric date format. This is '''''the''''' correct way to write numeric dates:

::2013-02-27

:The following formats are therefore discouraged:
:*02/27/2013
:*02/27/13
:*27/02/2013
:*27/02/13
:*20130227
:*2013.02.27
:*27.02.13
:*27-02-13
:*27.2.13
:*2013. II. 27.
:*27⁄2-13
:*2013.158904109
:*MMXIII-II-XXVII
:*MMXIII LVII⁄CCCLXV
:*1330300800
:*((3+3)×(111+1)-1)×3/3-1/33
:*   2  272013 [the numbers 2013, 02, and 27 written overlapping each other]
:*10/11011/1101
:*02/27/20/13
:*2053112674378
:*[A black cat with 2-27-13 scrawled across its body in dripping white paint.]
:**Cat: ''Hissss''

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

Talk:2463: Astrophotography

2021-05-15T03:46:26Z

108.162.249.18:

So are any of those "balls" actually sunspots or the transit of Venus or something?
[[Special:Contributions/173.245.54.227|173.245.54.227]] 22:47, 14 May 2021 (UTC)

This looks like Destin from Smarter Every Day's lunar eclipse shot

https://youtu.be/Nk0MRxXqo9s?t=610

[[Special:Contributions/108.162.219.78|108.162.219.78]] 23:20, 14 May 2021 (UTC)Yeedle

Destin also caught the ISS transiting during a previous eclipse: https://youtu.be/lepQoU4oek4?t=230
[[User:Astroboy|Astroboy]] ([[User talk:Astroboy|talk]]) 02:11, 15 May 2021 (UTC)

This is actually really cool. [[User:ISaveXKCDpapers|ISaveXKCDpapers]] ([[User talk:ISaveXKCDpapers|talk]]) 02:26, 15 May 2021 (UTC)

It might have been better with two planes that didn't look like they were dangerously within normal flight separation distances. Given they're not obviously 1000ft (300m) vertically apart (and very likely in Opposite Conflict, heading-wise) horizontal separation depthwise to the image should make the two similar models towing (similarly-sized?) banners noticeably off-scale to each other, even with the extreme foreshortening from the much distant cameraman. (Maybe the viewing angle 'up the mountain' would provide sufficient composite diagonal separation to comply with Reduced Flight Levels for two planes obeying hemispherical RVSM, but still with notable off-scaling.) They could be a stunt-pair, of course, asked for and given ATC dispensation (further complicated by the banner-towing) to cross absurdly close (by normal, sane standards) as per a fast-jet criss-cross at an airshow. It might have been even more impressive if one had been a notably 'bigger' class of plane (but silouetted at the same or smaller size) towing a similarly (give or take) rescaled banner. [[Special:Contributions/162.158.158.131|162.158.158.131]] 02:43, 15 May 2021 (UTC)

I am really looking forward to seeing the simultaneous Eclipse and Transit of Venus [[Special:Contributions/108.162.249.18|108.162.249.18]] 03:46, 15 May 2021 (UTC)

135: Substitute

2021-05-14T00:20:50Z

108.162.249.18: /* Trivia */

{{comic
| number = 135
| date = July 31, 2006
| title = Substitute
| image = substitute.png
| titletext = YOU THINK THIS IS FUNNY?
}}

==Explanation==
This comic refers to the film ''{{w|Jurassic Park (film)|Jurassic Park}}'', a 1993 movie based on the 1990 novel by {{w|Michael Crichton}}. The film centers around a billionaire who bought an island and opened a zoo or theme park for dinosaurs that he has cloned from DNA recovered from blood found in fossilized mosquitoes. After a computer programmer shuts down the security systems to steal embryos for a rival company, several of the creatures, among which are the {{w|Velociraptor}}s subject of this comic, run loose and try to devour every human in the theme park.

Velociraptors (often shortened to "raptors") are a species of relatively small, carnivorous {{w|dinosaur}} that play a central role in the original film, as well as its sequels. In the film, herds of Velociraptors antagonize the main characters at various points, even entering buildings. According to newer researches, the Velociraptors in the film were erroneously based on the {{w|Utahraptor}} species of dinosaur. Unlike the movie, in which they are depicted as having a reptilian skin, both species of dinosaur in reality are theorized to have been feathered. The word "raptor" also refers to modern {{w|Bird of prey|birds of prey}}.

[[Randall]] is asked to substitute for [[Miss Lenhart]] in math class. The first page of the test he devises contains three questions, which have the recurring theme of humans running from said velociraptors. For the answers, see the [[135: Substitute #Trivia|trivia section.]] As Randall says in the comic: "This material is more vital than anything you've ever learned," the joke being that Randall is somehow fearful that such a thing could happen.

Velociraptors, and in particular, the irrational fear of being attacked by them in the modern world, [[:Category:Velociraptors|appear several times]] in [[xkcd]]. This is the second such instance; the first is [[87: Velociraptors]]

In the title text, Randall asks the kids whether they find this possibility humorous (and they rightfully should, considering that the chances of such a thing occuring are astronomically low).

==Transcript==
:[In a classroom, the board says "Math" on the top-left corner, and "Mr. Munroe" in the middle. A Cueball portrays Randall, standing in front of it, speaking to the class.]
:Randall: Miss Lenhart couldn't be here today, so she asked me to substitute.
:Randall: I've put out your tests. Please get started.

:[A student in the first row raises the exam paper and says:]
:Student: Mr. Munroe, Miss Lenhart never taught us this.

:Randall: That's because Miss Lenhart doesn't understand how important certain kinds of math are.
:Student: But this just looks--
:Randall: This material is more vital than anything you've ever learned
:Student: But--
:Randall: No buts.

:Randall: This is a matter of life and death.

:[Excerpt from the exam paper.]
:<tt>Name: _________</tt>

:[A stick figure is standing, hands over head. A velociraptor is running towards it.]

:<tt>1. The velociraptor spots you 40 meters away and attacks, accelerating at 4 m/s^2 to its top speed of 25 m/s. When it spots you, you begin to flee, quickly reaching your top speed of 6 m/s. How far can you get before you're caught and devoured?</tt>

:<tt>2. You're at the center of a 20m equilateral triangle with a raptor at each corner. The top raptor has a wounded leg and is limited to a top speed of 10 m/s.</tt>

:[A stick figure is shown in the above situation. The picture has a legend "<tt>(Not to scale).</tt>"]

:<tt>The raptors will run toward you. At what angle should you run to maximize the time you stay alive?</tt>

:<tt>3. Raptors can open doors, but they are slowed by them. Using the floor plan on the next page, plot a route through the building, assuming raptors take 5 minutes to open the first door and halve the time for each subsequent door. Remember, raptors run at 10 m/s and they do not know fear.</tt>

==Trivia==
*Answers to the first two questions can be found in [http://fora.xkcd.com/viewtopic.php?f=7&t=120&start=40 this topic] on the forum board.
**The first is 37.30194339616981 meters.
**The second is 18.6 degrees to either side of the wounded raptor.

{{comic discussion}}
[[Category:Comics featuring Miss Lenhart]]
[[Category:Comics featuring Randall Munroe]]
[[Category:Comics with color]]
[[Category:Velociraptors]]
[[Category:Math]]
[[Category:Physics]]
[[Category:Comics featuring Cueball]]

2455: Virus Consulting

2021-05-06T19:49:02Z

108.162.249.18:

{{comic
| number = 2455
| date = April 26, 2021
| title = Virus Consulting
| image = virus_consulting.png
| titletext = All our teams make an effort to stay optimistic, but I will say that once our virus division saw the vaccine efficacy data, they started asking for payment up front.
}}

==Explanation==
{{incomplete|Created by a COVID virus. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
This comic is another in a [[:Category:COVID-19|series of comics]] related to the {{w|2019–20 coronavirus outbreak|2020 pandemic}} of the {{w|coronavirus}} {{w|SARS-CoV-2}}, which causes {{w|COVID-19}}, specifically regarding the [[:Category:COVID-19 vaccine|COVID-19 vaccine]].

This comic imagines a scenario where [[Ponytail]] works for a {{w|consulting firm}}, which offers advice about viruses, specifically COVID-19. Ponytail tells a panel of people (the government?), consisting of [[Hairbun]], [[Cueball]] and [[Megan]], that though they are worried about COVID-19 variants, the fact that the number of people vaccinated is increasing considerably is a good sign. Hairbun then accuses Ponytail's firm of simply "telling them what they want to hear", accusing her firm of giving them false hope to make them keep retaining her firm.

The punchline comes in the final panel where it turns out that Ponytail's colleague, [[Black Hat]], is consulting a different set of clients, which are the viruses themselves. He presents the exact same graph to the viruses and gives them the opposite message: though COVID-19 variants seem to be exciting to them, vaccination numbers are terrible news to their propagation and survival. This repeats the idea of [[2287: Pathogen Resistance]] where the pandemic is seen from the virus' perspective. As in that previous comic, it is the virus that is in a lot of trouble, which is another way of saying that humanity stands a good chance of surviving this situation. (That humanity will survive is also good for the virus, which needs living humans so that it can spread.)

The fact that another member of Ponytail's firm is telling clients that they should be worried is what Ponytail refers to when claiming that her firm does not simply tell clients what they want to hear.

Secondarily, the comic is making fun of the perception that consulting firms will offer their services to whoever can pay, even if they are harmful to society, a perception with {{w|McKinsey & Company#Controversies|some basis in fact}}

This would not be the first time that Black Hat has given advice to natural disasters that can kill humans, see [[1754: Tornado Safety Tips]].

{{w|Variants of SARS-CoV-2|SARS-CoV-2 variants}}, commonly called "COVID variants", have been in the news. The SARS-CoV-2 virus has mutated into many different strains, some of which spread more easily among humans. It is unknown whether the different variants have a greater individual fatality rate. The current SARS-CoV-2 vaccines from Pfizer-BioNTech and Moderna as well as the Regeneron therapeutic monoclonal
antibodies all effectively protect against at least the New York ({{w|Lineage B.1.526}}), South African ({{w|Lineage B.1.351}}), and U.K. ({{w|Lineage B.1.1.7}}) variants according to [https://www.nytimes.com/2021/04/22/health/covid-ny-variant-vaccine.html two recent study preprints] released April 22, 2021. Further research and peer review is ongoing.

The title text notes that the firm's "virus division" (the group advising the viruses themselves) has started to get worried that their jobs are becoming obsolete, due to vaccine efficacy. Thus, they are demanding to be paid "up front", before consulting/advising services have been rendered to their clients. Dependent upon the expectations of each party, payment can be asked for "up front", deferred for invoicing once services have been rendered, or a combination of the two. The weaker party to a contract may need to submit their transaction, or a guarantor, before the other spends too much effort in fulfilling their side of the contract.

==Transcript==
:[Ponytail stands in front a chart, with a labeled graph with an upward-curving line at the top, and several box-and-whisker plots below, with unreadable text and labels. She is holding a pointer towards the plot while addressing a panel in front of her to the left. The panel is seated behind a desk and is composed of Hairbun, Cueball and Megan. Cueball has one arm on the desk.]
:Ponytail: Now, I know you're worried about the variants, but this graph should be encouraging.
:Ponytail: Your rollout is going well. The vaccines are good. They work.
:Label on graph: Vaccinations

:[Same setting in a narrower panel without the chart. Ponytail has the pointer to her side. Cueball has his arms under the desk as the other two.]
:Hairbun: You're just telling us what we want to hear.
:Ponytail: If you think that, you should see the reports from my colleagues who work for COVID.

:[Close-up of Ponytail in a very narrow panel.]
:Off-screen voice: They work for '''''who??'''''
:Ponytail: Our firm has lots of clients.

:[Black Hat stands in front of an identical chart as in panel one, and points to it with a pointer in the same way as Ponytail did. Only he is looking to the right at his clients. He is speaking to a panel of three large coronaviruses, two of which floats above the desk, the middle one is partly below the desk. Across the top frame of the panel there is a box with a caption:]
:Meanwhile...
:Black Hat: Now, I know you're excited about the variants, but this graph should be terrifying.
:Black Hat: We're in real trouble here.
:Label on graph: Vaccinations

{{comic discussion}}

[[Category:COVID-19]]
[[Category:COVID-19 vaccine]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairbun]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Black Hat]]

2452: Aviation Firsts

2021-04-23T22:00:32Z

108.162.249.18: /* Cultural references */ [Citation needed] about impediments to sex in space

{{comic
| number = 2452
| date = April 19, 2021
| title = Aviation Firsts
| image = aviation_firsts.png
| titletext = Mile High Club membership [✓] [ ] Discovery of parts of Amelia Earhart's skeleton [ ] [ ] Mid-flight incident that results in safe landing on the Hudson River [✓] [ ]
}}

==Explanation==
{{incomplete|Created by D. B. COOPER OF MARS. Put a table detailing all the events of the achievement checklist with an Earth and Mars column. Do NOT delete this tag too soon.}}
This comic reflects the [https://twitter.com/NASAPersevere/status/1384209173924089863 ''Ingenuity'' probe's first flight on Mars]. Now that ''Ingenuity'' has completed its first flight, Mars can be counted among planets with controlled powered flight. The preceding categories in the list were completed by the first space probes to reach and then land on Mars. Flight, landing and controlled landing were variously achieved by some or all of the prior landers, depending upon your definition of flight, but certainly by the {{w|Mars_Science_Laboratory#Sky_crane_landing|Skycrane}} element used in landing both ''Curiosity'' and ''Perseverance'' rovers. These may not have qualified as controlled powered flight as they only used their power to control the landing, before flying off again under power without any more precise control than that needed to intentionally crash elsewhere.

The remaining have only been completed on Earth, if at all. A {{w|Aerobatic_maneuver|loop}} does not yet seem to be practical or necessary to attempt over Mars, and the rest grow more bizarre and more specific further down the comic and extending into the title text.

Planetary circumnavigation has been achieved by {{w|List_of_Mars_orbiters|many Mars orbiters}} but this is a list of ''aviation'' firsts, which would require controlled flight within an atmosphere.

===Cultural references===
* The {{w|Hughes H-4 Hercules}} (the "Spruce Goose") was a prototype wooden airplane, known for being the largest flying boat ever constructed. The Hercules was designed by aviation pioneer (and, latterly, famed recluse) Howard Hughes. The design was intended as a lightweight transoceanic transport for the the military, but the prototype, built out of wood because of aluminum shortages during World War II, was not completed until well after the end of the war and flew only a single time in 1947. Since 1991, it has been on permanent display at the {{w|Evergreen Aviation & Space Museum}} in McMinnville, Oregon, USA.

* In 1971, Northwest Orient Airlines Flight 305 was famously hijacked by a man who bought a ticket under the pseudonym "{{w|D. B. Cooper|Dan Cooper}}" (but popularly known as D. B. Cooper). After being given a $200,000 ransom by the plane's crew, Cooper proceeded to parachute jump out of the plane using the rear {{w|airstair}} and was never confirmed to have been heard from again; many experts agree that the parachute jump was very risky and it's unlikely that Cooper survived. (Cooper was previously mentioned in [[1400: D.B. Cooper]] and [[1501: Mysteries]].)

* The "{{w|mile high club}}" is a slang term for people who have had sexual intercourse while onboard an airplane in flight. Although the notion of {{w|sex in space}} is understood to be severely hampered by the limited life support and the complete lack of natural gravity,{{Citation needed}} it's not certain whether Mars's low gravity (compared to Earth) would make it similarly challenging to have intercourse within the planet's atmosphere.

* {{w|Amelia Earhart}} was an aviator who, along with her navigator {{w|Fred Noonan}}, went missing over the Pacific Ocean in 1937 while attempting a global circumnavigation flight and has never been found. While there's some possibility that some of Earhart and Noonan's remains will eventually be discovered somewhere in the Pacific, the notion of them somehow ending up on the surface of Mars is practically impossible outside the remit of certain conspiracy theories. (Earhart was previously mentioned in [[1501: Mysteries]], [[950: Mystery Solved]], and [[2197: Game Show]].)

* The {{w|US Airways Flight 1549|Miracle on the Hudson}} was a 2009 aviation incident in which a US Airways airliner struck a flock of geese shortly after takeoff from LaGuardia Airport in New York City. Despite the plane losing all its engine power as a result of the bird strike, Captain Chesley Sullenberger successfully crash-landed in the nearby Hudson River with minimal injuries to the passengers onboard. Of course, it would be highly impractical for a powered flight that encounters a problem in the sky above Mars to then fly all the way to Earth just for an emergency landing in the New York area (assuming the "Hudson River" in question wouldn't instead refer to a similarly-named river on a terraformed Mars).

==Transcript==
:[A chart is shown with nine items. To the right of each item there are two check boxes. Above the top row of check boxes are two underlined labels for the two columns. The first four rows have both boxes checked, and the last five have only the first box checked. The last two items are so long that they take up three and four rows of text. The first seven items are written on one line each.]

Earth Mars
Flight <big>[✓]</big> <big>[✓]</big>

Landing <big>[✓]</big> <big>[✓]</big>

Controlled landing <big>[✓]</big> <big>[✓]</big>

Controlled powered flight <big>[✓]</big> <big>[✓]</big>

Loop <big>[✓]</big> <big>[ ]</big>

In-flight meal <big>[✓]</big> <big>[ ]</big>

Planetary circumnavigation <big>[✓]</big> <big>[ ]</big>

Enormous wooden aircraft
built by a reclusive billionaire <big>[✓]</big> <big>[ ]</big>
that flies exactly once

Hijacking by someone dubbed
"D.B. Cooper" who demands <big>[✓]</big> <big>[ ]</big>
money and then jumps out
mid-flight to an unknown fate

{{comic discussion}}
[[Category:Mars rovers]]
[[Category:Charts]]
[[Category:Comics featuring real people]]