explain xkcd - User contributions [en]

2440: Epistemic Uncertainty

2021-08-04T00:39:52Z

108.162.246.17: I think that the explanation is done.

{{comic
| number = 2440
| date = March 22, 2021
| title = Epistemic Uncertainty
| image = epistemic_uncertainty.png
| titletext = Luckily, unlike in our previous study, we have no reason to believe Evangeline the Adulterator gained access to our stored doses.
}}

==Explanation==

This comic is a comparison of two different research studies. One of these studies shows "regular uncertainty". One of these studies shows "epistemic uncertainty." In both panels, the core data is the same. The drug in question is 74% effective. However, the uncertainty qualities are different. The first is straightforward. The confidence interval (the error bars on the chart) is from 63 to 81%. The second panel includes the additional wrinkle of "George the Data Tamperer, whose whims are unpredictable."

In statistics, a {{w|confidence interval}} is an estimate which provides a range of values. These values are based on the statistical probability that the data collected represents a certain result. The confidence interval is a reflection on the uncertainty imposed by the limits of study sample sizes. No study will ever have an infinite data set.{{Citation needed}} As a result, it is possible for different studies to give slightly different results. Averaging the results of multiple studies can give a result that is probably more accurate. The result given may still be skewed. A small skew is more probable than a large one, though. For example, if a drug was 80% effective it would be possible for several small studies to show a spread of different results with an average of 74% effectiveness. If the drug was 99% effective it would still be possible to randomly end up with the same data. However, this would be highly unlikely. This gives us a spread of "likely" predictions. Predictions outside a certain interval are considered too unlikely to be realistic.

George the Tamperer and Evangeline the Adulterator (from the title text) are analogous to the characters from {{w|Alice and Bob}} cryptography thought experiments. In the most basic examples, Alice and Bob are communicating. A third party, Eve the Eavesdropper, is spying on them. Both George and Evangeline have the ability to alter the study's results. George and Evangeline add uncertainty to the final data product. Specifically, they add ''epistemic'' uncertainty.

{{w|Epistemology}} – unlike {{w|epidemiology}} – is the branch of philosophy related to knowledge. Thus epistemic uncertainty is the ultimate impossibility to be sure that what we know is accurate. We are not unsure what is accurate beause of failures in measurement. We are unsure what is accurate because of the intrinsic limits of knowledge. It seems that the "epistemic uncertainty" data has a 25% chance of data {{w|tampering}} by George. In the previous study, the data is known but its reflection of the general case is uncertain to an extent. In contrast, in this study even the knowledge of whether any single data point is correct is uncertain. Thus, their data has a 25% chance of being incorrect. There is no possible statement about how incorrect it may be.

The title text mentions an individual called "Evangeline the Adulterator." She [https://www.dictionary.com/browse/adulterate adulterates] their drug doses. If this happened, the researchers would not even be sure the patients received the dosages (or exacting medicines/placebos) as prescribed. The study methodology itself would be in doubt.

==Transcript==
:[Two panels are shown with labels above them.]
:Regular Uncertainty
:Epistemic Uncertainty

:[In both panels Megan stands in front of a data presentation on a slide behind her. She is pointing at the slide with a stick.]

:[In the left panel titled 'Regular Uncertainty'. Megan standing in front of a presentation of a graph showing, from top to bottom, the number 74%, a horizontal line with a small black diamond near the middle representing an average with error bars, and a line of dots representing data in a horizontal scatter plot.]
:Megan: Our study found the drug was 74% effective, with a confidence interval from 63% to 81%.
:74%

:[In the right panel titled 'Epistemic Uncertainty'. Megan stands in front of a presentation of data with a silhouette of a man with a hat labelled with a white question mark. Above this are three guesses of the "real" result and its relation to the study result.]
:Megan: Our study found the drug to be 74% effective.
:Megan: However, there is a 1 in 4 chance that our study was modified by George the Data Tamperer, whose whims are unpredictable.
:73 -> 74??
:47 -> 74??
:0 -> 74??
:?

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Statistics]]
[[Category:Research Papers]]
[[Category:Biology]]

1994: Repairs

2019-11-25T18:43:48Z

108.162.246.17: /* Explanation */

{{comic
| number = 1994
| date = May 16, 2018
| title = Repairs
| image = repairs.png
| titletext = I was just disassembling it over the course of five hours so it would fit in the trash more efficiently.
}}

==Explanation==
This graph depicts the sentiment created by the act of repairing something, depending on the time it took (x-axis) and ensuing result (y-axis). The degree of triumph and exultation (expressed in sentences in quotes inside the graph) is strongly enhanced by the time the operation takes, and is also positively correlated with the result (if any). Actions during the repair process are described in sentences without quotes.
The conclusions are rather optimistic; the most negative feeling expressed (after the maximum time of repair with minimum degree of success) is a threat against other objects that might have plans to break.

The graph shows a main path most of his fixes apparently usually take (solid line) along with some variations they sometimes take (dotted lines). Projects usually start out with items that mostly work, but have minor problems. Occasionally they just need a cleaning (first dotted line). If that doesn't work, he takes them partly apart, and then there are times he's able to put them back together and get them to either work completely (one branch of a dotted line) or get it back to the condition it started out in (other branch of a dotted line), at which point he doesn't tempt fate by continuing, knowing what's likely to happen if he continues messing with it. When it's still not working, he takes it apart more completely, starts doing less reversible things like cutting wires, and finally starts watching {{w|YouTube}} videos hopefully showing the right way to fix it, or at least how others fixed it. This takes it to a state just one step above "Will never work again", after which there can be several results: One dotted line shows it's restored to being fully fixed and he feels victorious and proud that all the hard work paid off, and he thinks he deserves a {{w|Nobel Prize}} for his efforts. The next dotted line is when he gets it partially working again, and gives up, satisfied to at least not have completely destroyed it even though it's a little worse than before. The third, main path result is total failure, which he could take as a personal failure but to which he instead responds with humor by admonishing the rest of his possessions not to develop minor problems otherwise the same total destruction might happen to them. This path ends up a partial step below "Will never work again" so it's unclear what that state is... maybe that's the "throw it away" state.

The title text shows another excuse for failure. Nobody would spend five hours being a trash compactor. One could however claim to be separating the different parts for sorting into recycling bins, or separating the parts that aren't themselves damaged by the process from those that will no longer be of use to anyone. This still doesn't have any tangible benefits for the one doing the sorting (although it might earn them points with the recipient).

A similar sentiment was expressed in [[349: Success]]. However, in [[349: Success]] the computer would keep developing new problems and putting Cueball in worse and worse situations while in this comic it is just that Randall has increasing trouble fixing the issue as time wears on.

==Transcript==
:[Caption above the diagram:]
:'''<big>How well something works</big>'''
:After I decide to fix it

:[The comic shows a graph with a solid curve that decreases in 8 different sized steps from the top left to the bottom right. The X-axis shows time passes and gives the time from zero to five hours with 6 ticks with labels beneath. The Y-axis shows how well something works with 8 ticks, but only four of them labeled.]

:Works great
:Has minor problems
:Doesn't work

:Will never work again

:0 hours   1 hour   2 hours   3 hours   4 hours   5 hours

:[The solid line has six labels with eight arrow pointing to different sections, two times the same label has two arrows pointing to different sections the first two places where the lines takes a step down, and the second to two plateaus on either side of a step. In total the arrows point four times on both steps and plateaus. Both the first and final plateau has a dot has added to the line, and the arrows point to those. Above the solid line there are three dotted lines going up from three plateaus just before the solid line takes a step down, the last two of these lines split up in two, with one going higher. At the end of each of these five dotted lines there is a sentence spoken. The solid line begins at the 2nd tick on the Y-Axis and finishes at the last. The three dotted lines going up ends up at the 1. tick on the Y-axis, for the last two there are also a line ending at the 2nd tick and 3rd tick respectively. Only the first label being above the first tick on the X-axis but the last three labels are all above the last tick on the X-Axis. Here is a list of all the labels in chronological order according to the position on the X-axis. For those that has the same time stamp the top one will be mentioned first. Those at the end of a line are indented:]
:I start trying to fix it
::"It just needed cleaning!"
:Take it apart
::"Fixed it!"
::"Well, at least it's not ''more'' broken than when I started."
:Take it apart more
:Watch YouTube instructional videos
:Take a deep breath and cut wires
::"That was heroic and I deserve a Nobel prize."
::"Well, it ''sort'' of works now."
:(Turn to other possessions)
::"...And let that be a lesson to you."

==Trivia==
*The initial version of the normal sized image at [[xkcd]] was [http://www.explainxkcd.com/wiki/images/archive/d/de/20180516052839%21repairs.png broken]. This was later repaired.

{{comic discussion}}

[[Category:Line graphs]]

1011: Baby Names

2019-08-26T02:51:52Z

108.162.246.17: Noticed a joke I never noticed before, but I don't know any specific movie with a record scratch. Someone who knows what they are talking about should probably rewrite the sentence I added.

{{comic
| number = 1011
| date = February 1, 2012
| title = Baby Names
| image = baby names.png
| titletext = I've been trying for a couple years now but I haven't been able to come up with a name dumber than 'Renesmee'.
}}

==Explanation==

This comic is a list of comically terrible baby names invented by Randall. It may relate to his other comics about why he shouldn't be allowed to have access to babies.

This is a list of the names with a short description:
* Ponzi - An Italian surname, most often associated with "{{w|Ponzi scheme}}".
* Eeemily - A corruption of "Emily". May also be a marketing plug for the {{w|Asus Eee}} brand.
* Fire Fire - Even a single "Fire" would be odd as a name, at least in the American dialects. It would also not be a good idea to call your child's name in a crowded place.
* Chipotla - A frequent mispronounciation of {{w|Chipotle|chipotle}} chili or the popular {{w|Chipotle Mexican Grill}} restaurant chain. Many people would readily attempt to correct you when you called your child's name.
* Astamouthe - Could be pronounced "Ass to mouth".
* Eggsperm - A child is conceived by combining an egg and a sperm, this child's name is conceived by combining the names of the two things.
* [sound of record scratch] - This cannot be spelled or reliably pronounced. Likely a reference to any movie where a record scratch plays and the protagonist says "that's me".
* Parsley - {{w|Parsley}} is an herb and is not commonly used as a name unlike other herbs like {{w|Rosemary}} and {{w|Sage}}.
* Hot'n'Juicy Ann - "Ann" is a normal name. Prefacing it with the sexual "Hot'n'Juicy" would not be appropriate for a child's name.
* Ovari - Female reproductive organ, {{w|Ovary|misspelled}}.
* Friendly - Odd enough on its own, but when referring to her possessions it would create confusion with the restaurant {{w|Friendly's}}. Can also be humorous in introductions - "Hi I'm Friendly and I hate you."
* Sean (pronounced "seen") - While this isn't an incorrect pronunciation, the more common pronunciation would be "Shawn". Very likely a reference to the name of the actor Sean Bean (whose name is pronounced Shawn Been), which uses the exact same pairing of letters for two pronunciations.
* Joyst - Corruption of "Joyce". May also refer to the term "joist", which is a beam used in construction to support ceilings or floors, or the first part of the word "joystick", a video game controller.

A further analysis of baby names is presented by Randall in the [[Blag]] post "[http://blog.xkcd.com/2014/01/31/the-baby-name-wizard/ The Baby Name Wizard]".

Renesmee (from the title text) is the name of {{w|Renesmee Cullen#Renesmee Cullen|Renesmee Cullen}}, who is the baby born in the book and movie {{w|Breaking Dawn}} to parents Edward and Bella. Edward and Bella get "Renesmee" from an amalgamation of the names of Bella's mother, Renée, and Edward's adoptive mother, Esme. [[Randall]]'s point is that all those names are terrible, but (arguably) not nearly as terrible as the name Renesmee.

==Transcript==
:[Cueball sits at a desk, thinking with his hand on his chin, his other hand holding a pen over a piece of paper. Megan stands behind him, looking over his shoulder, also with her hand on her chin.]

:[Above the drawing is the list they are writing by hand.]

:Names for daughter

:# Ponzi
:# Eeemily
:# Fire Fire
:# Chipotla
:# Astamouthe
:# Eggsperm
:# [sound of record scratch]
:# Parsley
:# Hot'n'Juicy Ann
:# Ovari
:# Friendly
:# Sean (pronounced "seen")
:# Joyst

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

2045: Social Media Announcement

2018-09-12T13:58:17Z

108.162.246.17:

{{comic
| number = 2045
| date = September 12, 2018
| title = Social Media Announcement
| image = social_media_announcement.png
| titletext = Why I'm Moving Most of My Social Activity to Slack, Then Creating a Second Slack to Avoid the People in the First One, Then Giving Up on Social Interaction Completely, Then Going Back to Texting
}}

==Explanation==
{{incomplete|Please edit the explanation and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

In 2018, especially after {{w|Facebook}} privacy abuses were revealed in the Cambrige Analytica scandal, many individuals began seeking alternatives. The #deletefacebook hashtag peaked around April 2018, and in some communities, this type of "why I'm leaving Facebook" announcements were popular.

{{w|Mastodon (software)|Mastodon}}, misspelled by [[Cueball]] as ''Mastadon'', is a distributed, federated social network with microblogging features similar to {{w|Twitter}}. "Federated" means that there is one app hosted in many places, so users can choose a host that meets their needs, but everyone can still talk to each other, similar to email. Near the peak of #deletefacebook, mastodon became trending as a [https://motherboard.vice.com/en_us/article/783akg/mastodon-is-like-twitter-without-nazis-so-why-are-we-not-using-it twitter alternative with less nazis].

{{w|Wil Wheaton}} famously moved to Mastodon from Twitter, [https://news.avclub.com/wil-wheaton-on-quitting-social-media-i-don-t-deserve-1828743467 but was ultimately disappointed by the experience], because while Mastodon's community is generally less toxic, it does not yet have the tools to handle the kind of targeted harassment that a celebrity might face.

{{w|Microsoft}} has been buying up professional-themed social media platforms lately, such as {{w|LinkedIn}}, intending to integrate them more fluidly with their enterprise software suite. Mastodon seems an unlikely target for an acquisition, since its decentralized nature means that one corporate entity can't control it, and the culture there is decidedly unprofessional as of this comic.

The title text presents an alternative approach by moving most social activities to the cloud-based proprietary team collaboration platform {{w|Slack (software)|Slack}}, whose one important paid feature is the ability to search through archived messages without any limit (Wikipedia is wrong here, only free users are limited.), and probably because there were too many annoying communications he then creates a new account to get rid of the old messages. This also didn't last long and he stops interacting on social media entirely. As a result he just writes texts and probably not showing it to anyone.

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

:[Cueball sitting in front of a laptop typing.]
:Why I'm quitting Facebook, joining LinkedIn, deleting my LinkedIn, rejoining Facebook, quitting Twitter, getting locked out of Facebook, moving to Mastadon, and lobbying Microsoft to take over Mastadon and merge it with LinkedIn: A manifesto.

==Trivia==
Mastodon is misspelled as "Mastadon".

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Social networking]]

2039: Begging the Question

2018-08-29T17:26:28Z

108.162.246.17: /* Explanation */ Initial draft

{{comic
| number = 2039
| date = August 29, 2018
| title = Begging the Question
| image = begging_the_question.png
| titletext = At least we can all agree on the enormity of this usage.
}}

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

This comic makes fun of the constant battle between those who maintain a prescriptive view of language and those who have a descriptive view. In the prescriptive view, language has fixed rules and fixed usage, and any usage that does not adhere to established rules is incorrect. In the descriptive view however, language is malleable and any usage can be correct if it is common and understood by most people.

The comic specifically calls out two phrases which are commonly misused in the prescriptive sense, and whose meanings have changed in modern usage in the descriptive sense:
*Nauseous
*Begging the question

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

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Language]]

Talk:866: Compass and Straightedge

2018-08-08T16:26:24Z

108.162.246.17: Suggested reference

No, the comic is funny because many geometrical theorems prove something along the lines of "With a compass and straightedge you cannot construct..." (e.g. a square and a circle with the same area) If you have knowledge of this type of proof, the humor is that you think he's about to talk about something that is impossible in geometry, but really he's talking about the inapplicability of geometry to real life. This is often a difficulty with nerds and brainy people, they try to apply their theoretical knowledge to human relationships and fail. [[Special:Contributions/75.103.23.206|75.103.23.206]] 19:53, 13 December 2012 (UTC)
:And then there's the converse: people who are able to apply theoretical knowledge and succeed. [[Special:Contributions/76.106.251.87|76.106.251.87]] 04:33, 5 June 2013 (UTC)

The explanation mentions that there are "three such constructions", but doesn't go any further. What they are should at least be addressed (or linked to), even if we're not going to elaborate on the "why" of their impossibility. For the uninitiated, they are squaring the circle, trisecting any angle, and doubling the cube. [[Special:Contributions/76.106.251.87|76.106.251.87]] 04:33, 5 June 2013 (UTC)

If such constructions are "impossible with the use of modern algebraic techniques," then why don't we just use older algebraic techniques? ;){{unsigned ip|213.203.138.251}}
:Those "modern algebraic techniques" just did prove that you can't solve this constructions by using only "classical geometry".--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 18:14, 29 June 2013 (UTC)

I tried forming a club for compasses and straight edges but no one signed up :( ~JFreund

Could the “most awsome birthday party“ bear another deeper meaning, for example be analogue to the rational polynom with rational coefficients?
[[Special:Contributions/162.158.202.100|162.158.202.100]] 04:30, 9 April 2017 (UTC)

Could this "most awesome birthday party" be a reference to Stephen Hawking's party for time travelers?
[[User:Spagovir|Spagovir]] ([[User talk:Spagovir|talk]]) 18:33, 10 August 2017 (UTC)
: I'm pretty sure you're right, it sounds like a Hawking party reference to me too. - [[User:CRGreathouse|CRGreathouse]] ([[User talk:CRGreathouse|talk]]) 06:17, 8 August 2018 (UTC)

Anyone think of adding a reference to 710 Collatz Conjecture? Where in a similar vein, he begins by explaining the steps for applying the conjecture, then finishes up by losing all his friends. [[Special:Contributions/108.162.246.17|108.162.246.17]] 16:26, 8 August 2018 (UTC)

2022: Sports Champions

2018-07-20T05:33:17Z

108.162.246.17: /* Explanation */

{{comic
| number = 2022
| date = July 20, 2018
| title = Sports Champions
| image = sports_champions.png
| titletext = For a long time, people thought maybe Usain Bolt was the one for running, until the 2090s and the incredible dominance of Derek Legs.
}}

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

In an example of {{w|Nominative determinism}}, the cartoon lists people whose surname relates to their participation in various sports.

{| class="wikitable"
!style="width:20%"|Name
!style="width:10%"|Year
!style="width:70%"|Explanation
|-
|Margaret Court
|1960s
|{{w|Margaret Court}} is a real Australian tennis player, former world number 1, who won many competitions in the 1960s and 70s. A {{w|tennis court}} is the playing arena used in that sport.
|-
|Gary Player
|1970s
|{{w|Gary Player}} is a real South African golf player who won nine major championships in the 1960s and 70s. Game contestants are often known as "players".
|-
|Lonzo Ball
|2020s
|Lonzo Anderson Ball is a real American professional basketball player for the Los Angeles Lakers. Basketball is played with a ball.
|-
|Jake Halfpipe
|2030s
|Jake Halfpipe is a fictitious professional snowboarder. A half-pipe is a structure used in gravity extreme sports such as snowboarding.
|-
|Sarah Goggles
|2030s
|
|-
|Julia Chairlift
|2050s
|
|-
|Dwight Shuttlecock
|2060s
|
|-
|Brandon Sponsorship
|2060s
|
|-
|Kate Dopingscandal
|2070s
|
|-
|Jebediah Disasterous Postgame PressConference
|2080s
|
|}

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

{{comic discussion}}

2022: Sports Champions

2018-07-20T05:30:42Z

108.162.246.17: /* Explanation */

{{comic
| number = 2022
| date = July 20, 2018
| title = Sports Champions
| image = sports_champions.png
| titletext = For a long time, people thought maybe Usain Bolt was the one for running, until the 2090s and the incredible dominance of Derek Legs.
}}

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

In an example of {{w|Nominative determinism}}, the cartoon lists people whose surname relates to their participation in various sports.

{| class="wikitable"
!style="width:20%"|Name
!style="width:10%"|Year
!style="width:70%"|Explanation
|-
|Margaret Court
|1960s
|{{w|Margaret Court}} is a real Australian tennis player, former world number 1, who won many competitions in the 1960s and 70s. A {{w|tennis court}} is the playing arena used in that sport.
|-
|Gary Player
|1970s
|{{w|Gary Player}} is a real South African golf player who won nine major championships in the 1960s and 70s. Game contestants are often known as "players".
|-
|Lonzo Ball
|2020s
|Lonzo Anderson Ball is a real American professional basketball player for the Los Angeles Lakers. Basketball is played with a ball.
|-
|Jake Halfpipe
|2030s
|
|-
|Sarah Goggles
|2030s
|
|-
|Julia Chairlift
|2050s
|
|-
|Dwight Shuttlecock
|2060s
|
|-
|Brandon Sponsorship
|2060s
|
|-
|Kate Dopingscandal
|2070s
|
|-
|Jebediah Disasterous Postgame PressConference
|2080s
|
|}

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

{{comic discussion}}

1061: EST

2018-06-11T22:33:10Z

108.162.246.17: /* Length of year */

{{comic
| number = 1061
| date = May 28, 2012
| title = EST
| image = est.png
| titletext = The month names are the same, except that the fourth month only has the name 'April' in even-numbered years, and is otherwise unnamed.
}}

==Explanation==
This comic pokes fun of attempts to "fix" the calendar by making it simpler or more rational, which inevitably result in a system just as complicated. This is an example of the paradox in complexity theory that if you attempt to simplify a system of problems by creating a new system of evaluation for the problems you often have instead made the problem more complex than it was originally.

[[Randall]] advertises his idea for a "Universal Calendar for a Universal Planet". He combines {{w|calendar#Calendars in use|calendar}} definitions with {{w|Time zone|time zone}} definitions. The abbreviation '''EST''' in this comic stands for ''Earth Standard Time'' (hence the title), but it is in itself a joke on the American {{w|Eastern Time Zone|Eastern Standard Time}}. In the rest of the explanation EST refers to the comic's Earth Standard Time!

===Length of year===
Because there are approximately 365.2422 days in a {{w|solar year}}, various calendars use different means to keep the calendar year in sync with the solar year and the seasons. The Julian Calendar, for example, has leap days every four years, giving it an average year length of 365.25 days. The most widely used system is the {{w|Gregorian Calendar|Gregorian Calendar}}, which also has leap days every four years, but skips leap days in years divisible by 100 unless the year is also divisible by 400, the latter additions come from Earth's {{w|axial precession}}. This gives it an average year length of 365.2425 days, which is very close to the length of a solar year (see detailed explanation in this video: ''[https://www.youtube.com/watch?v=82p-DYgGFjI Earth's motion around the Sun, not as simple as I thought]''.)
{{w|Calendar reform|Other calendars}} have been proposed, such not counting leap days and special "festival days" as a day of the week, in order to make every date fall on the same day of the week every year.

*At "24 hours 4 minutes", EST days are longer, though there are only 360 of them in the year. The extra 4 minutes over the course of 360 days adds up to one standard day, so Randall's EST calendar would at this point have a year that is 361 standard days long. The 24 hours plus 4 minutes length may be a reference to {{w|sidereal day}}, whose duration is 24 hours ''minus'' 4 minutes.

*Running the clock backwards for 4 hours after every full moon gives 8 additional hours at each full moon, twelve or thirteen times in a year. Because a thirteenth full moon will occur once every 2.7 solar years on average, this modification adds 4.1228 standard days to an EST year, bringing it to 365.1228 days.

*The doubling of the non-prime numbers of the first non-reversed hour after each solstice and equinox is a final, very complicated way to bring Randall's EST year in extremely close sync with the solar year. There are 17 prime numbers between 0 and 59 and 43 non-primes. There are 2 equinoxes and 2 solstices each year, so a total of 4x43 = 172 minutes will occur twice. This brings the average length of Randall's EST year to 365.2422 standard days, equal to the solar year to four decimal places.

===Claimed benefits===
Many of the claimed benefits for the calendar are highly dubious:
*While it is fairly ''simple'' to describe, EST is far from simple to understand or put in practice. Clocks in particular would have to regularly undertake very complicated processes like running backwards or duplicating non-prime minutes.
*EST does appear to be fairly ''clearly defined''.
*EST fails completely to be ''unambiguous''. Following each full moon, four hours occur three times, twice forward and once backward. Several minutes are also duplicated, making times during those periods ambiguous.
*The only way EST is ''free of historical baggage'' is that it breaks free of any sensible bits of historical baggage; it keeps such things as the 30-day month and 12-month year, but adopts a different (and variable) length of day that would make it wildly out of sync with the Earth's day-night cycle.
*EST is ''compatible with old units'', as far as seconds, minutes, and hours are concerned, though not for days, months, or years.
*EST is indeed very ''precisely synced with the solar cycle''. The joke is that this has nothing to do with the day/night cycle or the Earth's yearly orbital cycle; the {{w|solar cycle}} is a period of magnetic fluctuation within the sun, lasting 11 Earth years.
*EST is ''free of leap years'', though some EST years are 8 hours longer than others on account of having an extra full moon.
*A calendar ''amenable to date math'' makes it easy to find the length of time between two dates and times by having standardized periods of time. The complex variability of the length of EST years, days, and hours mean it is only ''intermittently'' amenable to date math, which is to say not at all.

===Other features===
The features of the calendar get increasingly bizarre as the description proceeds:

*The {{w|Epoch (reference date)|Epoch}} for EST is set by reference to the {{w|Julian calendar}}, which was superseded by the {{w|Gregorian calendar}}. The Julian calendar is currently 13 days behind the Gregorian calendar.

*The different zone for the United Kingdom is a reference to 1 yard being equal to 0.9144 meters, a pun on using {{w|imperial units}} instead of the {{w|metric system}}. This has been the joke before in [[526: Converting to Metric]] and is also mentioned in [[1643: Degrees]].

*Randall does not like {{w|Daylight saving time}} (DST) very much, as has been made clear in [[:Category:Daylight saving time|several comics]] both before and after this one. See Narnian time below.

*Narnian time is a reference to the fictitious world of {{w|Narnia (world)|Narnia}} in {{w|CS Lewis|CS Lewis'}} book {{w|The Lion, The Witch and The Wardrobe}} and its sequels. In Narnia, time passes much more quickly than in the real world. You could be in Narnia for several days and only a few minutes would have passed in the real world. However, synchronizing this effect would be impossible because it is not a consistent rate; it fluctuates wildly based on the whims of drama and magic. This and the DST mentioned above should be seen as a pair. Because when a country goes into DST time may not pass, which is basically what happens (more or less) when a child enters into Narnia. Whereas in EST Narnian time is synchronized to normal time, which DST is but for the one hour difference in the real calender. Using the weird Narnian time was used as the plot in the bottom left drawing in [[821: Five-Minute Comics: Part 3]].

*The Gregorian calendar does not include the year "0"; after "1" BC the next year is "1" AD. Randall's invention fixes this according to correct Mathematics, only to reintroduce the problem immediately by arbitrarily omitting the year 1958. The year 1958 is significant because January 1, 1958 is the epoch (time zero) in {{w|International Atomic Time}} (TAI), which is part of the basis for {{w|Coordinated Universal Time}} (UTC). (The main difference is that TAI doesn't add leap seconds.)

*The title text's concept of only naming the fourth month ''April'' in the even numbered years, and then leave it unnamed the other years, may be a reference to the ancient (Pre-Babylonian Exile) [http://www.jewfaq.org/calendar.htm Jewish Calendar], which did not name the months, rather assigning them numbers from 1 to 12 (or 13 in leap years, where an extra month was added instead of an extra day). The names used by Jews today are the names of the Babylonian months, derived from various Babylonian deities or events in Jewish history or on the calendar.

==Transcript==
:[Caption and text above the main panel:]
:xkcd presents
:<big>Earth Standard Time</big>
:(EST)
:A universal calendar for a universal planet
:EST is...
:Simple • Clearly defined • Unambiguous
:Free of historical baggage • Compatible with old units
:Precisely synced with the solar cycle • Free of leap years
:Intermittently amenable to date math

:[A list of the details concerning EST:]
:Units
:{|
|-
| style="text-align:right;" | Second:
| 1 S.I. second
|-
| style="text-align:right;" | Minute:
| 60 seconds
|-
| style="text-align:right;" | Hour:
| 60 minutes
|-
| style="text-align:right;" | Day:
| 1444 minutes (24 hours 4 minutes)
|-
| style="text-align:right;" | Month:
| 30 Days
|-
| style="text-align:right;" | Year:
| 12 months
|}

:Rules
:For 4 hours after every full moon, run clocks backward.
:The non-prime-numbered minutes of the first full non-reversed hour after a solstice or equinox happen twice.

:{|
|-
| style="text-align:right;" | Epoch
|    
| Time Zones
|-
| style="text-align:right;" | 00:00:00 EST
|
| The two EST time zones are
|-
| style="text-align:right;" | January 1, 1970 = 00:00:00 GMT
|
|   ''EST'' and ''EST (United Kingdom)''
|-
| style="text-align:right;" | January 1, 1970 (Julian calendar)
|
| These are the same except that the UK second is 0.9144 standard seconds
|}

:{|
|-
| style="text-align:right;" | Daylight saving:
| Countries may enter DST, but no time may pass there.
|-
| style="text-align:right;" | Narnian Time:
| Synchronized✔
|-
| style="text-align:right;" | Year Zero:
| EST ''does'' have a year 0. (However, there is no 1958.)
|}

{{comic discussion}}

[[Category:Time]]
[[Category:Daylight saving time]]
[[Category:Astronomy]]
[[Category:Chronicles of Narnia]]

Talk:1922: Interferometry

2017-11-30T04:49:51Z

108.162.246.17: comment

Newbie here just added the explanition and transcript, so will need editing.[[Special:Contributions/172.68.34.106|172.68.34.106]] 16:25, 29 November 2017 (UTC)
:I think we both added it at the same time; when I submitted mine it showed normally in the edit box with the captcha, but when I pressed save it spliced your explanation and mine together. Think yours is probably better researched (I was typing off the top of my head), so I reverted it again. -- [[Special:Contributions/162.158.89.25|162.158.89.25]] 16:43, 29 November 2017 (UTC)
Why is there a period after Interferometry in the first panel?[[Special:Contributions/172.68.34.106|172.68.34.106]] 19:04, 29 November 2017 (UTC)

I really like the [citation needed] on whether dogs can interfere with each other. I want it to stay! --[[Special:Contributions/162.158.89.61|162.158.89.61]] 20:05, 29 November 2017 (UTC)

Beret guy is back ! I like it... [[Special:Contributions/172.69.23.51|172.69.23.51]] 00:05, 30 November 2017 (UTC)

I feel it should be noted that these are good dogs, Brent. --[[Special:Contributions/108.162.246.17|108.162.246.17]] 04:49, 30 November 2017 (UTC)

1826: Birdwatching

2017-04-21T00:25:47Z

108.162.246.17: /* Transcript */ Added apostrophes.

{{comic
| number = 1826
| date = April 19, 2017
| title = Birdwatching
| image = birdwatching_small.png
| titletext = No, tell the park rangers to calm down, it's fine--I put a screen on the front. I just want to get the birds a little closer.
}}

==Explanation==
{{incomplete|Needs more information on birdwatching specifically about using binoculars vs. a superzoom (or just large zoom) camera, and if it is correct how the explanation say it is more difficult with the camera or if it is just an inexperienced Cueball that is the reason for the trouble.}}
In this comic [[Cueball]] and his [[1350:_Lorenz#Knit_Cap_Girl|friend with a knit cap]] are out birdwatching (hence the title). {{w|Birdwatching}} is an activity to observe birds. Usually this is done at a distance, as birds are flying in the air, and are far away. It is thus helpful to use {{w|binoculars}}.

Cueball's friend uses binoculars and manages to spot a {{w|hawk}} a mile up. Cueball, however, has brought his camera, probably his superzoom camera from [[1719: Superzoom]]. But it is very difficult to find anything in such a camera if you zoom in first. And maybe Cueball is with his trained friend, out birdwatching for the first time. Cueball is frustrated and comments on the difficulty and is amazed his friend can spot birds over such distances.

Frustrated with his camera Cueball comes up with a solution, which is to use a {{w|vacuum cleaner}}, specifically a {{w|shop vac}}, to pull the birds in closer so he won't need the superzoom camera to see them (this he has just left on the ground next to the shop vac). This is physically impossible with such a small device. Even if the shop vac created a perfect vacuum, it can only pull out air at the speed of sound, which amounts to approximately 1 cubic meter per second considering the apparent size of the hose. This is not enough to create a significant amount of wind or affect the atmosphere. (Of course he may have borrowed it from his other friend [[Beret Guy]] who has many [[:Category:Strange powers of Beret Guy|strange powers]] that also extends to improving vacuum cleaners, which Cueball knows about as seen in [[1486: Vacuum]]).

The title text refers to {{w|park ranger}}s, who would naturally be distressed by birds being forced to coalesce via an extremely powerful vacuum. If such a vacuum were created and used for this purpose, it probably would pose a threat to said birds. Cueball says he has solved this problem by placing a perforated screen in front. In doing so, he can safely attract the birds without trapping them inside the vacuum. He implies that this should remove the danger to the birds, which is not the case. While the birds can no longer enter the vacuum itself, having a large number of birds pulled into a (presumably small) screen would probably fare poorly for the birds, so Cueball's solution is rather poor.

When out birdwatching it is a great idea to have a silhouette chart to be able to recognize the birds by the shadow they make against the sky. Two comics before this one [[Randall]] made a comic with just such a chart, [[1824: Identification Chart]], although that was for combinations of birds and planes...

==Transcript==
:[Cueball and his friend with a knit cap are standing together looking up in the sky. Cueball holds a camera with a large lens down in front of him, and his friend holds binoculars down in front of him.]
:Cueball: Birdwatching is hard.
:Cueball: They're all way too small and far away.

:[In a frame-less panel they both raise their tool eyepieces to their eyes.]
:Cueball: That hawk is over a mile up! How did you even spot it?

:[Both lower their eyepiece again. The friend still looks up while Cueball looks down on his camera which he holds up in front of him. A black squiggly line above his head indicates that he is fuming over his camera's abilities.]

:[Cueball now has a vacuum cleaner with a big body and a large hose which he is pointing towards the sky, as air is visibly sucked in to the hose and the vacuum cleaner is making a very loud noise which extends beyond the frame of the panel.Cueball is holding one hand on the vacuum cleaner which has a label with its brand on it. Cueball's camera lies on the ground in front of the vacuum cleaner. The friend looks back at Cueball.]
:Vacuum cleaner: <big>'''''Whrrrrr'''''</big>
:Label: Shop Vac

==Trivia==
*This comic was originally published with a very large picture, much larger than the standard screen.
**The original image was named [https://imgs.xkcd.com/comics/birdwatching_huge.png birdwatching_huge.png]
**The image at that location has also been downsized to normal dimensions.
**It was later updated to use an image without the "_huge" in its name, at the usual size.
*The unexpected size was at first interpreted as being part of the joke, see the [[#Discussion|discussion page]].
**The idea was that the reader was only seeing an inconvenient subset of the magnified image on the screen, just like Cueball was experiencing an inconvenient subset of the magnified sky through the zoom of his camera lens.
**It seems, however, that it wasn't meant to be like this, as both the size and name of the image were later corrected.
*Alternatively the size gave people trouble with reading the page, and made Randall change his mind and reset it to normal size.
**It seems weird he would make a "_huge" version by mistake?

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Characters with Hats]]
[[Category:Animals]]

1788: Barge

2017-01-20T15:27:27Z

108.162.246.17: Fixed typos and added explanation for title text

{{comic
| number = 1788
| date = January 20, 2017
| title = Barge
| image = barge.png
| titletext = My life goal is to launch a barge into the air and have it land on one of Elon Musk's rockets.
}}

==Explanation==
{{incomplete|Needs more information on the title text}}

This is another one of the "my hobby" series, where someone, it is assumed Cueball, tells about a strange hobby. This is probably the most destructive one so far, where Cueball empties out a barge, puts on a sheet of paper with the spaceEx logo, and floats it near launch sites. The goal of that hobby is to get SpaceEx rockets to land on the barge, causing them to crash through the paper and fall into the sea. Careful logic brings up the idea that this particular entry in the "my hobby" series in not made by Cueball at all, but instead has been sneaked into Cueball's diary by Black Hat. However, even if it is Black Hat has done this, it would still be his most destructive idea of all time.

The title text takes this idea further by making the barge into a rocket and then having the barge land of one of Elon Musk's rockets. Because of this, the rocket may be bent or dented on the top.

==Transcript==
{{incomplete transcript}}

{{comic discussion}}

1247: The Mother of All Suspicious Files

2017-01-13T21:33:25Z

108.162.246.17: /* Explanation */ "The mother of all (item)" is a common phrase and not a known reference to any other example.

{{comic
| number = 1247
| date = August 5, 2013
| title = The Mother of All Suspicious Files
| image = the_mother_of_all_suspicious_files.png
| titletext = Better change the URL to 'https' before downloading.
}}

==Explanation==
The save dialogue shows a download from [http://en.utrace.de/?query=65.222.202.53 65.222.202.53], an IP address that hosted JavaScript malware during a recent attack on the Tor anonymity network, with a very long file title. Many of the extensions used inside there indicate executable code; multiple file extensions are sometimes used to disguise a trojan program as a document.

You also see common download syntax for a pirated movie, {{w|Hackers (film)|Hackers}}, likely included to appear malicious to anyone skimming but is actually a movie about hackers, making it a benign reference rather than malicious. It is described as "_BLURAY_CAM", which contradicts itself ("_BLURAY" would mean it was ripped from a copy on Blu-ray Disc, while "_CAM" would mean it was copied by pointing a camera at the screen in the cinema). "_BLURAY_CAM" would probably indicate a search-keyword-stuffed fake copy; fake pirated media often contain viruses (although this is more likely to be a problem with newer media, before the first real pirated copy appears).

The {{w|URL}} contains the path "~tilde/pub/cia-bin/etc". The first part is a public folder of a user named tilde (which is also the name for the ~ symbol), "cgi-bin" is a common folder on a Web-Server for server side executables ([[Randall]] changes the name to [[CIA]]-bin), and "etc" is a standard folder for configuration files – normally never accessible through a webserver. The program "init.dll" isn't executable at all, it's a {{w|Windows Dynamic Link Library}} which can't be run standalone, and is rarely referenced in URLs (even though such syntax is still being employed, even on [https://www.google.com/search?q=site:edu+filetype:dll reputable websites (Google search)] or here at [https://signin.ebay.com/ws/eBayISAPI.dll eBay], indicating the webserver is a Microsoft {{w|Active Server Pages|ASP}} server). The question mark indicates the start of a parameter list, and in this case we have only one named "FILE".

The "Save" button is disabled; you can only click the "Cancel" button. This can be different when the server detects that you are using a secure (https) connection.

The complete content sent to the server, starting with "/~TILDE..." and ending with "...OUT.EXE", is exactly 256 characters long. On {{w|HTML 3}} specifications you have a limitation of 1024 characters, whereas later HTML specifications don't have this limit; it just depends on the web server's capabilities. But posting parameters directly at the URL is still a worse choice.

The content of the parameter is shown here:
*__ (underscore underscore) — used in the C programming language to denote that a symbol is really not for public consumption.
*{{w|AUTOEXEC.BAT}} — a file which is automatically run during startup on Windows/DOS operating systems, and was often modified by viruses, which added malicious code to be run on each boot.
*MY%20OSX%20DOCUMENTS — referencing the {{w|OSX}} operating system ({{w|URL encoding#Character data|%20}} is a representation of a space in a URL, i.e. it reads as "MY OSX DOCUMENTS").
*INSTALL.EXE — a typical {{w|Installer#Installer|installer}}.
*{{w|RAR}} — a compressed archive file type.
*{{w|INI file|INI}} — a configuration file type.
*{{w|Tar (computing)|TAR}} — a file archive popular in UNIX and UNIX-like operating systems. TAR has been mentioned [[1168: tar|before]].
*DOÇX — {{w|docx}} is an Office Open XML file, i.e. a word processing format used by Microsoft Word 2007 and above, but has no cedilla (¸). The addition of a cedilla may be a reference to exploits that rely on rare characters being mistaken for more common ones that look similar, such as the {{w|IDN homograph attack}}.
*PHPHPHP — a play on {{w|PHP}} files, a kind of server-based web page file type. PHP originally stood for "Personal Home Page" but was later redefined as the recursive abbreviation "PHP: Hypertext Preprocessor".
*{{w|XHTML}} — another web page file type.
*{{w|TransducerML|TML}} — stands for Transducer Markup Language, an XML based markup language that specifies how to capture, time-tag and describe sensor data.
*XTL — possibly a play on XHTML.
*TXXT — a play on {{w|Text file|TXT}} file types.
*0DAY.HACK — a reference to a {{w|zero-day exploit}}. (overlaps with the next entry)
*HACK.ERS_(1995)_BLURAY_CAM-XVID — a reference to the 1995 {{W|Hackers (film)|''Hackers''}} movie, but pirated movies would either be a BlurayRIP/DVDRIP or CAM, but not both at the same time unless you used a camera to record the Blu-ray movie as it played.
*{{w|EXE}} — an executable file type used by Microsoft Windows.
*[SCR] — a tag used by movie pirates to denote a '{{w|Screener}}', the DVD copy of films given to critics prior to theater release. Usually the highest quality available at the time, rare, and thus good bait for a virus-laden download. "{{w|.scr}}" is also the extension for screensaver files, really just an exe file with a different extension and one of the classical ways to distribute infected files.
*{{w|Lisp (programming language)|LISP}} — programming language.
*{{w|Windows Installer|MSI}} — an installation file used by Microsoft Installer.
*{{w|.lnk|LNK}} — an extension used by Microsoft Windows for shortcuts. The extension is normally hidden to the user.
*LNK, ZDA, GNN — references to {{w|Link (The Legend of Zelda)|Link}}, {{w|Princess Zelda|Zelda}}, and {{w|Ganon}}, important characters from ''{{w|The Legend of Zelda}}'' video game franchise.
*{{w|White Rabbit#Television and films|WRBT.OBJ}} — A reference to the line of code Dennis Nedry used in {{w|Jurassic Park (film)|Jurassic Park}} to shut down key systems.
*{{w|Object file|O}} — The extension for a linker file, an intermediary created when compiling C code.
*{{w|Header file|H}} — The file extension of a header file in C code.
*{{w|SWF}} — Shockwave Flash file type.
*{{w|Dpkg|DPKG}} — The Debian package management, although the package files use the file suffix ''.deb''.
*APP — an application on Mac OS X operating system.
*{{w|ZIP (file format)|ZIP}} — compressed archive file type.
*CO — the {{w|List of Internet top-level domains|top-level domain (TLD)}} for Colombia, but marketed as a global domain. Some countries use .co.''TLD'' for general use, e.g. ''.co.uk'' in the United Kingdom. But the TLD ''.gz'' does not exist and thus ''.co.gz'' is invalid.
*{{w|Gzip|GZ}} — a compressed file using GNU zip.
*{{w|A.out|A.OUT}} — Default filename when creating an executable on Linux or other UNIX-like operating systems if none was specified for the compiler.

The title text suggests changing from ''http'' to ''https'', as if encrypting a suspicious file before downloading it is somehow better than downloading it unencrypted. http (Hyper Text Transfer Protocol) and https (Hyper Text Transfer Protocol - Secure) are the two common protocols for getting web pages and web downloads. http is the simple download, whereas https adds an SSL encryption layer so the item being downloaded cannot be viewed unencrypted by anyone except the end recipient. Changing ''http'' to ''https'' is a common suggestion to improve security when browsing the web from an insecure network (such as a public WiFi hotspot) to avoid surveillance or hijacking to a malicious website; Google automatically switches to https for all mail accounts and is starting to do so with searches. The end recipient will still get whatever nasties were in the original, however — encrypting it doesn't change the content at all.

The IP address referenced in the comic, 65.222.202.53, is currently being used by the shellcode of a JavaScript 0-day exploit for the Tor Browser Bundle being run by the FBI to phone home over the clearnet [http://thehackernews.com/2013/08/Firefox-Exploit-Tor-Network-child-pornography-Freedom-Hosting.html] and de-anonymize visitors to websites on Freedom Hosting that are serving child pornography. [http://www.reddit.com/r/onions/comments/1jmrta/founder_of_the_freedom_hosting_arrested_held/]

==Transcript==
:[Browser download warning box containing the following text.]
:WARNING!
:This type of file can harm your computer! Are you sure you want to download:
:<nowiki>http://65.222.202.53/~TILDE/PUB/CIA-BIN/ETC/INIT.DLL?FILE=__AUTOEXEC.BAT.MY%20OSX%20DOCUMENTS-INSTALL.EXE.RAR.INI.TAR.DOÇX.PHPHPHP.XHTML.TML.XTL.TXXT.0DAY.HACK.ERS_(1995)_BLURAY_CAM-XVID.EXE.TAR.[SCR].LISP.MSI.LNK.ZDA.GNN.WRBT.OBJ.O.H.SWF.DPKG.APP.ZIP.TAR.TAR.CO.GZ.A.OUT.EXE</nowiki>
:[Cancel and Save buttons (Save button disabled)]

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]
[[Category:Video games]]