explain xkcd - User contributions [en]

1944: The End of the Rainbow

2018-01-19T17:02:46Z

172.68.11.41: /* Explanation */ water in the oceans

{{comic
| number = 1944
| date = January 19, 2018
| title = The End of the Rainbow
| image = the_end_of_the_rainbow.png
| titletext = The retina is the exposed surface of the brain, so if you think about a pot of gold while looking at a rainbow, then there's one at BOTH ends.
}}

==Explanation==
{{incomplete|Edited by a leprechaun. We are here. We are watching. The bit about percentages of the mass of the Sun should be made more readable. Also need to explain title text.}}
[[Cueball]] and [[Megan]] are having a discussion. Megan brings up the myth that at the end of every {{w|rainbow}} lies a {{w|leprechaun}}'s pot of gold. Instead of claiming that leprechauns and their gold don't exist, Cueball refutes that technically, rainbows are circles, so they do not have an end.

However, Megan then expands on the scientific explanation Cueball is stating. She states that if one considers the path light takes to form a rainbow, then it forms a two-cone structure, where the Sun (the vertex of the outer cone) emits light rays that move towards the Earth (forming the faces of the outer cone), then reflect off of water droplets located at just the right angle (the circular base) to reach our eyes (the vertex of the inner cone ). Thus, such a rainbow structure ''can'' be said to have "ends", represented by the vertices of the two cones: one at the eye of the viewer, and another at the light source.

Megan then says that the Sun is indeed a pot of gold. The Sun is approximately 1.989 × 10^30 (1 nonillion 989 octillion) kilograms, and its abundance of gold is approximately 0.3 parts per trillion. Based on these numbers, the sun contains 5.967 × 10^17 (596 quadrillion 700 trillion) kilograms of gold. This equates to 5.967 × 10^14 (596 trillion 700 billion) metric tons of gold. As such, Megan's statement that the sun contains "quintillions of tons of gold" is off by a factor of roughly 4000. But the amount of gold within the sun is far more than a pot's worth nonetheless.

The amount of water in the oceans is about 1.35 × 10^18 (1 quintillion 350 quadrillion) metric tons. This means that Megan's next statement (that there is more gold in the sun than water in the oceans) is off by a factor of roughly 2300 (though it would have been true if the previous one was).

As of January 19, 2017, the value of gold is 42,692.98 USD per kilogram. Based on this, all of the gold in the sun is worth 2.5474901 × 10^22 (25 sextillion 474 quintillion 901 quadrillion) USD.

Cueball then asks about leprechauns. Megan replies that the leprechauns all died when the Sun formed, implying all the gold in the Sun is actually the remnants of leprechaun gold. However, she does not consider the explanation where the leprechaun is on the other end of the rainbow...

The title text suggest that since the pot of gold exists in the brains of people thinking about it, and the retina is the foremost part of the brain for the light perception, it can be argued that, in addition to existing in the sun as the comic explains, the gold (and leprechauns) also exist at the other end, in the retina and brain of the person seeing the rainbow.

==Transcript==

:[Megan and Cueball are walking.]
:Megan: There's a pot of gold at the end of the rainbow.
:Cueball: Rainbows are circles. They have no end.
:Megan: Not quite!

:[In a borderless panel, a multi-part graphic is shown depicting what Megan is describing off-panel: a short cone inside a longer cone, with the longer cone having its point starting at the Sun, the shorter cone having its point at a miniature Cueball's head, and both cones sharing the same circular base. The diagram is repeated from 3 different perspectives to make the structure easier to grasp.]
:Megan (off-panel): A '''rainbow''' is light leaving the Sun, bouncing off the clouds, and converging on your eye. It's an inside-out two-ended cone.

:[Megan and Cueball are still walking.]
:Megan: One end of that cone is your retina.

:[A wider view of the same scene, with Megan and Cueball walking on a dark ground.]
:Megan: The other end is the Sun—which contains quintillions of tons of gold. There's more gold in the Sun than water in the oceans.
:Cueball: So there ''is'' a pot of gold!
:Cueball: What about leprechauns?
:Megan: All incinerated as the sun formed. Very sad.

{{comic discussion}}
[[Category:Comics_featuring_Megan]]
[[Category:Comics_featuring_Cueball]]

1810: Chat Systems

2017-03-15T09:17:55Z

172.68.11.41: /* Chat systems */ original Unix wall didn't accept message as an argument

{{comic
| number = 1810
| date = March 13, 2017
| title = Chat Systems
| image = chat_systems.png
| titletext = I'm one of the few Instagram users who connects solely through the Unix 'talk' gateway.
}}

==Explanation==
{{incomplete|More info needed?}}
The comic shows an {{w|Euler diagram}} with many different {{w|Online chat|chat systems}} connection possibilities and their overlaps. This is used to explain the relationship between social networks and [[Randall|Randall's]] acquaintances who use them. (Euler diagrams should not be confused with {{w|Venn diagram}}s, see more on this [[:Category:Venn diagrams|here]]).

In the world of {{w|social media}} and [[:Category:Social networking|social networking]], it is extremely easy to communicate with people through the various messaging systems provided. Unfortunately, this can also become very confusing when one (such as Randall in this comic) knows many people who use various combinations of the different chat systems.

Below is a [[#Chat systems|table]] with explanation for all 24 mentioned chat systems and below that a list of each systems [[#Euler intersections|intersections]] with the other systems. Several of the systems are already considered old but, like ''The "chat" tab in an old {{w|Google Doc}}'', but some people keep using them, which is part of the joke. There only seems to be one "chat" system which could in no way be said to be an on-line chat system, and that is the ''Wall (bathroom)'' at the bottom, which refers to how people writes notes on public bathroom walls, making it the only extra joke apart from the mess in the main diagram. It may be a reference to [[229: Graffiti]].

In the title text, Randall explains how he is one of the only few {{w|Instagram}} users to use the {{w|Unix}} {{w|Talk_(software)|'talk' gateway}} an old peer-to-peer chat system whereby users logged into the same UNIX system could privately communicate with each other in a full-screen interface. This implies that he also uses a complicated system of communication.

The ubiquity of standards - here, of messaging systems - was already covered in [[927: Standards]] and people's hesitation to switch off IRC was mentioned in [[1782: Team Chat]]. The same point about people using various chat systems was used in [[1254: Preferred Chat System]]. And famously the hidden chat room mentioned in [[1305: Undocumented Feature]], was later created by Randall through the [[:Category:April fools' comics|April fools' comic]] [[1506: xkcloud]] - see the [[1506:_xkcloud#Don.27t_contact_us|Don't contact us]] section.

===Chat systems===
*The 24 chat systems are listed with the systems having most people at the top, and that number is also listed before the explanation.
**Notice there are only 23 real systems, as one of the systems is a bathroom wall.
*See below for each systems [[#Euler intersections|intersections]] with the other systems.
{| class="wikitable"
!System
!Number of people in group
!Explanation
|-
| {{w|SMS}}
|39
|Short Message System; a text-based messaging system connecting most worldwide phone systems that had its beginnings in the 1980s and has since represented the most common form of data transmission for most people. It is principally used to send short text messages between mobile phones, but most phone carriers provide facilities to send-to-email or send-to-voice (for use with landline phones). Most major phone carriers also provide support for email-to-SMS.
|-
| {{w|Email}}
|35
|A popular form of electronic communication that saw first widespread use in the 1960s. It allows you to send electronic "letters" to people using pre-exchanged email addresses. Many people use this platform, hence the large size of the corresponding circle.
|-
| {{w|Hangouts}}
|9
|Google Hangouts is Google's instant messaging system. It can be used to share data and for video chat.
|-
| {{w|Signal_(software)|Signal}}
|8
| An app used for encrypted communications.
|-
| {{w|iMessage}}
|6
|Apple's SMS service
|-
| {{w|IRC}}
|5
|Internet Relay Chat; a chat protocol from the late 1980's that still sees considerable but declining use today. It is an open, freely available protocol with many free client apps available. Communications are principally in text and users typically use an app to connect to an IRC server, which may in turn be connected to other IRC servers. Many clients also provide for file sharing. There are many client and server plugins that provide access to other protocols (such as IRC-Hangouts, etc).
|-
| {{w|Slack_(software)|Slack}}
|5
|A team instant messaging service
|-
| {{w|Twitter|Twitter DM}}
|4
| "Direct messages" between users on Twitter.
|-
| {{w|AOL Instant Messenger|AIM}}
|2
|AOL Instant Messaging service; a popular messaging system from the 1990s that suffered a severe decline in 2005 upon the release of Gmail and Google Chat. It is based on the closed source OSCAR protocol, but AOL created the TOC/TOC2 protocol specifications, and made specifications openly available, for third parties to connect to their service. There have been short-lived dalliances with other protocols since 2008; it has never had direct support for the other widely used protocols here.
|-
|The "chat" tab in an old {{w|Google Doc}}
|2
|Google Docs is an online word processor reminiscent of Microsoft Word. One of the notable features is online collaborative editing, with a rudimentary chat feature for communication. Randall apparently communicates with someone using the chat in an old Google Doc.
|-
| {{w|Facebook_Messenger|FB Messenger}}
|2
|Facebook's chat system.
|-
| {{w|Instagram|Instagram DM}}
|2
|Direct Messaging, a feature of Instagram that allows users to post personal messages to each other.
|-
|{{w|Peach_(social_network)|Peach}}
|2
|Peach is a mobile-based social network introduced in January 2016.
|-
| Telegram
|2
|Could refer to a cloud based instant messaging system by this name ({{w|Telegram (software)|Telegram}}), or to actually sending messages using {{w|telegrams}}. Telegrams were messages sent by electric telegraphy, which were often typed out and hand-delivered to the recipient. This was the first system for rapid communication across long distances that was widely available, originally developed in the 19th century. Naturally, telegraphy is now wildly obsolete (though some local services apparently do still exist) which would explain why Randall communicates with so few people that way.
|-
| {{w|Skype}}
|2
|Microsoft's chat client. It offers VoIP video and audio calls, instant messaging and phoning from within the app.
|-
| {{w|WhatsApp}}
|2
|Billed as encrypted end-to-end chat, allows VoIP chats, text chats, video and image sharing. Caters for group chat as well.
|-
| {{w|WeChat}}
|2
| Started off as a Chinese WhatsApp imitation. WeChat has become a full scale social media with its own news, games and payment system.
|-
|{{w|Apache_HTTP_Server|Apache}} Request {{w|Server_log|Log}}
|1
|A file used by Apache HTML server to log page access requests by users, usually stored as access_log. Its use as a communications tool would require the user to embed their messages in URLs and the admin to look for the messages in the logs. It would be inconvenient and time consuming for both parties. It was implemented soon after here: [https://github.com/mdom/smokesignal github]
|-
| {{w|BlackBerry Messenger|BBM}}
|1
|Blackberry message. A chat system available on {{w|BlackBerry}} phones, now largely obsolete.
|-
| {{w|Snapchat}}
|1
|Snapchat is an image messaging app.
|-
|Wall (bathroom)
|1
|This is the only "other" joke in the comic as this is the only "system" not on-line. Apparently it is a chat system based around writing on the wall in the bathroom. Not an electronic system. It may thus be a reference to [[229: Graffiti]]. Leaving messages on public bathroom walls is a common form of {{w|graffiti}}. It may be used as a support for anonymous conversations. Alternatively, this could mean the person is an extreme introvert, and hides in his bathroom instead of interacting with others, by talking through the wall. It could also be a pun on "communicating through _____" as a bathroom wall is a physical object rather than an interface. It could also refer to someone who has a habit of talking through the wall to people in adjacent stalls of a public bathroom.
|-
|{{w|Wall (Unix)}}
|1
|Short for "write all", the "wall" command copies its input to every user logged into the same Unix system, and so can be used as a primitive chat system.
|-
| {{w|Zephyr (protocol)}}
|1
| Zephyr was designed as an instant messaging protocol and application-suite with a heavy Unix background.
|-
| {{w|ICQ}}
|1
|An older open-source instant messaging application.
|}

===Euler intersections===
Here is a list of each item and its intersections from left top to right bottom is:
*Skype - none, Email
*Email - none, Skype, SMS, Slack, Hangouts, IRC, ICQ, iMessage, Signal, WhatsApp, Zephyr, FB Messenger, Instagram DM, BBM, Telegram, Twitter DM
*SMS - none, Email, Slack, Hangouts, IRC, Snapchat, iMessage, Signal, WeChat, WhatsApp, Zephyr, FB Messenger, Instagram DM, Peach, BBM, Twitter DM
*AIM - none
*Slack - Email, SMS, Hangouts, IRC, Signal
*Hangouts - Email, SMS, Slack, IRC, Signal
*IRC - Email, SMS, Slack, Hangouts, Signal
*Snapchat - SMS
*ICQ - Email
*iMessage - Email, SMS, Signal, FB Messenger
*Signal - Email, SMS, Slack, Hangouts, IRC, iMessage, Zephyr, Instagram DM
*WeChat - SMS
*WhatsApp - Email, SMS
*Zephyr - Email, SMS, Signal
*FB Messenger - Email, SMS, iMessage
*Instagram DM - Email, SMS, Signal
*Peach - SMS
*BBM - Email, SMS
*Telegram - none, Email
*Twitter DM - none, Email, SMS
*The "chat" tab in an old Google Doc - none
*Apache Request Log - none
*Wall (Unix) - none
*Wall (bathroom) - none

==Transcript==
:[A large panel with a complicated Euler diagram with 24 circle like drawings representing various chat systems. Most circles are embedded into others as two of the circles (SMS and Email) are much larger than all the others and many of the circles are overlapping each other in complicated ways. But five circles are single separate circles with no connections to others, and three more of the smaller circles are partly outside all others circles. Seven are fully embedded inside one or more circles without crossing any of the circles around them. Those five that do not overlap in any way with the two large circles do also not overlap with each other or any of the other circles. Inside all circles there are at least one character, but the two large circles have 39 (SMS) and 35 (Email) characters. All other have between one and nine characters. In total there are 57 characters. The characters are mainly standard characters like Cueball, Megan, Ponytail and Hairy. But also others are present. There is only one Blondie, and some with a white hair bun (but none drawn like Hairbun). It is noticeable that there are no characters with hats of any kind.]

:[Here follows a list of each chat systems name, the names are written on a break in the lines at the top of their circles. They are from left top to right bottom:]
:Skype
:Email
:SMS
:AIM
:Slack
:Hangouts
:IRC
:Snapchat
:ICQ
:iMessage
:Signal
:WeChat
:WhatsApp
:Zephyr
:FB Messenger
:Instagram DM
:Peach
:BBM
:Telegram
:Twitter DM
:The "chat" tab in an old Google Doc
:Apache Request Log
:Wall (Unix)
:Wall (bathroom)

:[Caption below the panel:]
:I have a hard time keeping track of which contacts use which chat systems.

==Trivia==
*There are 57 characters in the comic. Here is a version of the comic with numbered characters for reference:
[[File:1810 Chat System numbered.PNG]]

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Blondie]]
[[Category:Multiple Cueballs]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Blondie]]
[[Category:Multiple Cueballs]]
[[Category:Charts]]
[[Category:Social networking]]

Talk:1784: Bad Map Projection: Liquid Resize

2017-01-24T09:33:57Z

172.68.11.41:

I'm not too experienced with PhotoShop, but I think that the tool is a selective delete that he used on water bodies, so removing most of the water while maintaining relative shapes and sizes?
:Mostly just from the fact that India looks desiccated.
[[Special:Contributions/162.158.166.197|162.158.166.197]] 05:06, 11 January 2017 (UTC)Girish
::Australia is pretty mutilated, so I think the tool was used on land too [[Special:Contributions/162.158.178.111|162.158.178.111]] 05:55, 11 January 2017 (UTC)

Where are Laos and Cambodia missing? [[Special:Contributions/108.162.246.11|108.162.246.11]] 06:14, 11 January 2017 (UTC)
:It seems that Laos and Burma have been merged into one big county, as well as Cambodia and Thailand. Maybe they are just unnecessary details according to this map projection. [[Special:Contributions/162.158.238.22|162.158.238.22]] 16:39, 11 January 2017 (UTC)

The tool removes spaces of uniform color automagically. If you have big countries like India or Australia, they get caught by the algorithm as well. [[Special:Contributions/162.158.69.9|162.158.69.9]] 06:16, 11 January 2017 (UTC)

Can anybody figure out the projection before the application of the tool? [[Special:Contributions/108.162.219.232|108.162.219.232]] 06:58, 11 January 2017 (UTC)
:I think it is a Mercator projection that got mutilated. [[Special:Contributions/141.101.104.239|141.101.104.239]] 07:50, 11 January 2017 (UTC)
::I agree, it looks like a Mercator that Freddy Kruger got at.
Girish, [[Special:Contributions/162.158.166.197|162.158.166.197]] 09:02, 11 January 2017 (UTC)
:::I think if it was a Mercator, the bottom of Antarctica would be flat. To me, it looks like Winkel Tripel, with the odd angles in Alaska and the Russian Far East. [[User:Schroduck|Schroduck]] ([[User talk:Schroduck|talk]]) 15:02, 11 January 2017 (UTC)

I feel like there is some part of sarcasm in "unused blank spaces", as if it was Randall saying "You're right, why would anyone care about the oceans? There, I have removed them, problem solved.". Can anyone tie this to a recent event? Or maybe the joke is about improperly handling data, where you use a tool just because it's known to work well and for the sake of processing data, even if using in a given context doesn't make much sense. [[Special:Contributions/141.101.69.213|141.101.69.213]] 10:14, 11 January 2017 (UTC)
:I'm not sure about recent events, but "removing oceans" features prominently in one of Randall's [https://what-if.xkcd.com/53/ What If?] articles. {{unsigned ip|108.162.241.130}}

This map proves, once again, that it's good to be an archipelago. Philippines, FTW! [[Special:Contributions/172.68.54.58|172.68.54.58]] 13:59, 11 January 2017 (UTC)
:Hold your patriotic horses there, where did Palawan go? --[[Special:Contributions/162.158.138.10|162.158.138.10]] 12:24, 12 January 2017 (UTC)

Comics like these make me wonder how Randall preserves the XKCD visual style when working with content that is clearly not hand-drawn. <span style="background:#0064de;font-size:12px;padding:4px 12px;border-radius:8px;">[[User talk:AgentMuffin|<span style="color:#f0faff;">~AgentMuffin</span>]]</span>

"This is a play on the common advice to young children to refrain from "running with scissors" to avoid physical accidents." <-- Does anyone else thing this is a bit of a stretch? {{unsigned ip|108.162.245.130}}
:Yes, I do :) [[User:Luckykaa|Luckykaa]] ([[User talk:Luckykaa|talk]]) 15:46, 12 January 2017 (UTC)
: absolutely. Running just refers to the algorithm. It's not meta in any way.[[Special:Contributions/162.158.58.45|162.158.58.45]] 16:29, 12 January 2017 (UTC)

This map centres on Africa, which has survived the distortion relatively unscathed. Might this be a dig at other projections that exaggerate the relative size of Africa? For example, Gall-Peters is called out in {{xkcd|977}} with a simple "I hate you".
--[[Special:Contributions/108.162.241.130|108.162.241.130]] 15:47, 13 January 2017 (UTC)
:Maybe but I think it is because all landmasses are more or less centered around Africa. By putting this center there is not need to show any of the Earths half-sphere with the paccific Ocean, which would anyway disappear completely. I think it would be more difficult for people to relate to a map that shows USA up Against China, than US up against Europe. And that may be an important factor when making such a comic. People need to know what they see and what has happened to appreciate the comic. But I'm sure he appreciated that it keeps Greenland and Australia much smaller then Africa, which is not the case for the mercator projection. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 20:46, 17 January 2017 (UTC)

It seems to me that this comic is inspired by {{xkcd|1685}}, once again making humorous reference to using a Photoshop tool to accomplish an unrelated task. {{unsigned ip|108.162.215.130}}
:Agree. Will add [[1685: Patch]] to the explanation. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 20:46, 17 January 2017 (UTC)

Can someone please explain the relevance of "political" in the title? Because I understood the resizing of the map to be related to unused blank political space, so that areas with little or no political "content" were cut away, which seems to run counter to what everyone else thinks. But then again, I know absolutely nothing about actual map resizing.
:"Political" is a type of map which focuses on showing locations of countries, usually by painting neighbouring ones in different colors.[[Special:Contributions/172.68.11.41|172.68.11.41]] 09:33, 24 January 2017 (UTC)