https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=Helloworld&feedformat=atomexplain xkcd - User contributions [en]2024-03-28T17:02:31ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=2119:_Video_Orientation&diff=1705052119: Video Orientation2019-03-04T21:12:15Z<p>Helloworld: Undo revision 170504 by 162.158.106.6 (talk)</p>
<hr />
<div>{{comic<br />
| number = 2119<br />
| date = March 4, 2019<br />
| title = Video Orientation<br />
| image = video_orientation.png<br />
| titletext = CIRCULAR VIDEO - PROS: Solves aspect ratio problem. CONS: Never trust anyone who talks to you from inside a circle.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|This was created by a TRUSTWORTHY CIRCULAR VIDEO. Nothing about Bold and Dynamic. Bad dubious template. Better explanation on horizontal and vertical needed. DO NOT DELETE THIS TOO SOON (It already was once.)}}<br />
<br />
This comic compares different pros and cons of 3 video angles, one of which entirely made-up.<br />
<br />
Horizontal angling is: <br />
<br />
1. Good for people not used to phones, and has been used for centuries. (True)<br />
<br />
2. Not the best at capturing a human's entire body, without also capturing much of their surroundings. (True)<br />
<br />
3. Potentially uncomfortable for the one making the recording to maintain over a long period of time, as most phones were designed for vertical holding. (True)<br />
<br />
4. A more accurate visualization of the way humans view the world; we view approximately 150 degrees horizontally and only 50 degrees vertically. (Not stated in the comic)<br />
<br />
Vertical angling is: <br />
<br />
1. The norm for most users capturing video on their smartphone. (Questionable)<br />
<br />
2. Not ideal for capturing the background. (True, when not used in panoramic view)<br />
<br />
3. Better at capturing the whole body of a human subject. (True)<br />
<br />
4. Is less stressful on the hands of the one holding the mobile recording device. (Questionable)<br />
<br />
[[Randall]] does love a good [https://explainxkcd.com/690/ compromise], so he suggests "Diagonal Angling" as a third option to satisfy the needs of both types of user.<br />
<br />
Diagonal angling is: <br />
<br />
1. Not a standard format of video.{{Citation needed}} (True)<br />
<br />
2. Equally annoying to all viewers. (Almost certainly true)<br />
<br />
3. Flawless, as in perfect in every way.{{Dubious}} (False)<br />
<br />
The issue with this is that diagonal angling fails to fully capture the benefits of either horizontal or vertical angling.<br />
<br />
The titletext quip about circular video would be a reference to having a demon trapped inside a summoning circle, hence not trusting anything that would be said to you.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[The image shows three columns by three rows with the following headers:]<br />
:'''Video Orientation'''<br />
:'''Pros'''<br />
:'''Cons'''<br />
<br />
:[First row:]<br />
:[A wide picture with a text above:]<br />
:Horizontal<br />
:[Pros are:]<br />
:*Looks normal to old people<br />
:*Format used by a century of cinema<br />
:[Cons are:]<br />
:*Humans are taller than are wide<br />
:*I'm not turning my phone sideways<br />
<br />
:[Second row:]<br />
:[A high picture with a text above:]<br />
:Vertical<br />
:[Pros are:]<br />
:*How most normal people shoot and watch video now so we may as well accept it<br />
:[Cons are:]<br />
:*Human world is mostly a horizontal plane<br />
<br />
:[Third row:]<br />
:[A picture rotated by 45 degrees with a text above:]<br />
:Diagonal<br />
:[Pros are:]<br />
:*Bold and dynamic<br />
:*Equally annoying to all viewers<br />
:*Good compromise<br />
:[Cons are:]<br />
:*None<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Compromise]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=2119:_Video_Orientation&diff=1705032119: Video Orientation2019-03-04T21:06:53Z<p>Helloworld: Undo revision 170502 by 162.158.106.6 (talk) Stop trolling</p>
<hr />
<div>{{comic<br />
| number = 2119<br />
| date = March 4, 2019<br />
| title = Video Orientation<br />
| image = video_orientation.png<br />
| titletext = CIRCULAR VIDEO - PROS: Solves aspect ratio problem. CONS: Never trust anyone who talks to you from inside a circle.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|This was created by a TRUSTWORTHY CIRCULAR VIDEO. Nothing about Bold and Dynamic. Bad dubious template. Better explanation on horizontal and vertical needed. DO NOT DELETE THIS TOO SOON (It already was once.)}}<br />
<br />
This comic compares different pros and cons of 3 video angles, one of which entirely made-up.<br />
<br />
Horizontal angling is: <br />
<br />
1. Good for people not used to phones, and has been used for centuries. (True)<br />
<br />
2. Not the best at capturing a human's entire body, without also capturing much of their surroundings. (True)<br />
<br />
3. Potentially uncomfortable for the one making the recording to maintain over a long period of time, as most phones were designed for vertical holding. (True)<br />
<br />
4. A more accurate visualization of the way humans view the world; we view approximately 150 degrees horizontally and only 50 degrees vertically. (Not stated in the comic)<br />
<br />
Vertical angling is: <br />
<br />
1. The norm for most users capturing video on their smartphone. (Questionable)<br />
<br />
2. Not ideal for capturing the background. (True, when not used in panoramic view)<br />
<br />
3. Better at capturing the whole body of a human subject. (True)<br />
<br />
4. Is less stressful on the hands of the one holding the mobile recording device. (Questionable)<br />
<br />
[[Randall]] does love a good [https://explainxkcd.com/690/ compromise], so he suggests "Diagonal Angling" as a third option to satisfy the needs of both types of user.<br />
<br />
Diagonal angling is: <br />
<br />
1. Not a standard format of video.{{Citation needed}} (True)<br />
<br />
2. Equally annoying to all viewers. (Almost certainly true)<br />
<br />
3. Flawless, as in perfect in every way.{{Dubious}} (False)<br />
<br />
The issue with this is that diagonal angling fails to fully capture the benefits of either horizontal or vertical angling.<br />
<br />
The titletext quip about circular video would be a reference to having a demon trapped inside a summoning circle, hence not trusting anything that would be said to you.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
:[The image shows three columns by three rows with the following headers:]<br />
:'''Video Orientation'''<br />
:'''Pros'''<br />
:'''Cons'''<br />
<br />
:[First row:]<br />
:[A wide picture with a text above:]<br />
:Horizontal<br />
:[Pros are:]<br />
:*Looks normal to old people<br />
:*Format used by a century of cinema<br />
:[Cons are:]<br />
:*Humans are taller than are wide<br />
:*I'm not turning my phone sideways<br />
<br />
:[Second row:]<br />
:[A high picture with a text above:]<br />
:Vertical<br />
:[Pros are:]<br />
:*How most normal people shoot and watch video now so we may as well accept it<br />
:[Cons are:]<br />
:*Human world is mostly a horizontal plane<br />
<br />
:[Third row:]<br />
:[A picture rotated by 45 degrees with a text above:]<br />
:Diagonal<br />
:[Pros are:]<br />
:*Bold and dynamic<br />
:*Equally annoying to all viewers<br />
:*Good compromise<br />
:[Cons are:]<br />
:*None<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Compromise]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=2119:_Video_Orientation&diff=1704812119: Video Orientation2019-03-04T17:43:48Z<p>Helloworld: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 2119<br />
| date = March 4, 2019<br />
| title = Video Orientation<br />
| image = video_orientation.png<br />
| titletext = CIRCULAR VIDEO - PROS: Solves aspect ratio problem. CONS: Never trust anyone who talks to you from inside a circle.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|This was created by a TRUSTWORTHY CIRCULAR VIDEO. Nothing about Bold and Dynamic. Bad dubious template. Better explanation on horizontal and vertical needed. DO NOT DELETE THIS TOO SOON (It already was once.}}<br />
<br />
This comic compares different pros and cons of 3 video angles.<br />
<br />
Horizontal angling <br />
1. Good for people not used to phones and has been used for centuries. (True)<br />
2. Humans can’t be captured as well. (True if a full body shot is desired)<br />
3. Can be uncomfortable to hold the smartphone when recording and viewing. (True)<br />
4. It more accurately displays the way humans view the world: we view approximately 150 degrees horizontally and only 50 degrees vertically. (not stated in the comic)<br />
<br />
Vertical angling <br />
1. Is normal for most smartphone users. (True)<br />
2. Can’t capture the background well. (True, when not used in panoramic view)<br />
3. When the subject of the video is a human, it captures more of their body. (True)<br />
4. Is less stressful on the hands of the one holding the mobile recording device. (True)<br />
<br />
[[Randall]] does love a good [https://explainxkcd.com/690/ compromise], so he suggests the following angle:<br />
<br />
Diagonal angling <br />
1. Not a standard format of video {{Citation needed}} (True)<br />
2. Equally annoying to all viewers (Almost certainly true)<br />
3. Diagonal angling has no flaws, and is perfect in every way {{Dubious}}. (False)<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
Video Orientation<br />
{| class="wikitable"<br />
|-<br />
! Video Orientation<br />
! PROs<br />
! CONs<br />
|-<br />
| Horizontal<br />
| Looks normal to old people<br />
Format used by a century of cinema<br />
| Humans are taller than are wide<br />
I'm not turning my phone sideways<br />
|-<br />
| Vertical<br />
| How most normal people shoot and watch video now so we may as well accept it<br />
| Human world is mostly a horizontal plane<br />
|-<br />
| Diagonal<br />
| Bold and dynamic<br />
Equally annoying to all viewers<br />
<br />
Good compromise<br />
| None<br />
|}<br />
Title text: CIRCULAR VIDEO - PROS: Solves aspect ratio problem. CONS: Never trust anyone who talks to you from inside a circle.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Compromise]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=754:_Dependencies&diff=164171754: Dependencies2018-10-13T16:09:11Z<p>Helloworld: /* Transcript */ Space</p>
<hr />
<div>{{comic<br />
| number = 754<br />
| date = June 16, 2010<br />
| title = Dependencies<br />
| image = dependencies.png<br />
| titletext = The prereqs for CPSC 357, the class on package management, are CPSC 432, CPSC 357, and glibc2.5 or later.<br />
}}<br />
<br />
==Explanation==<br />
A compiler is a program that converts code, written in a particular programming language, into an executable program. A section of code is said to be dependent on a second segment of code if the results of the first segment are potentially impacted by the second segment. Dependency resolution is part of compiler design, and is the study of determining and correcting dependencies which result in an unwanted, ambiguous, or impossible definition of the dependent section. Requiring that an action occurs if and only if the action has already occurred, like the prerequisite in this comic, is one type of potentially unwanted dependency.<br />
<br />
The comic envisions a college computer science course (CPSC432) focusing on "compiler design with dependency resolution" which has itself as a prerequisite. The joke is that the prerequisite is an unresolved dependency, as you must complete this course before you can enroll in it, a phenomenon called {{w|Catch-22 (logic)|Catch-22}}.<br />
<br />
This dependency would send a poorly designed compiler into an infinite loop. In real life, the problem is solved by allowing an object to satisfy itself as a prerequisite. This stops the compiler's infinite loop, but may not produce the desired functionality in the program. Another layer of the joke may be that any student who successfully enrolls in the class already knows this solution because they must have employed it in order to get past the apparent infinite recursion in the class prerequisites.<br />
<br />
Managing dependencies is useful in other areas of computer science, e.g. {{w|package management}}. Collections of files are known as "packages". A software package might require that a particular operating system patch (a type of package) be installed first. That package might in turn require other packages be installed, and so on. Therefore, a package installer must know the dependencies of a package, and be able to figure out whether any required packages are missing before continuing with the installation. <br />
<br />
The title text envisions a course on package management which has itself as a prerequisite, as well as the compiler design course with the impossible prerequisite presented in the main comic (CPSC 432), and glibc2.5 or greater. By looking at the course number it can be observed that CPSC 432 is a fourth year course, and this package management course (CPSC 357) is a third year course. Glibc is a commonly used package on Unix systems, and therefore should be taught in the course. This continues the joke since this course has the following unresolved dependencies:<br />
*Requiring that the course be a prerequisite to itself (CPSC 357).<br />
*Requiring that a course with an unresolved dependency (CPSC 432) be a prerequisite, as CPSC 432 can not be taken.<br />
*Requiring that a fourth year course (CPSC 432) be a prerequisite to a third year course (CPSC 357), as the student should be in their fourth year while taking CPSC 432, and should be in their third year while taking CPSC 357. This is analogous to a lower-numbered package requiring a higher-numbered package.<br />
*Requiring that the student knows part or all of the course material (glibc2.5 or greater) before taking the course, as the student is supposed to learn this information from the course.<br />
<br />
==Transcript==<br />
:[A portion of a page from an imaginary course catalog.]<br />
:Page 3<br />
<br />
:[A table with four columns]<br />
<br />
:;Department<br />
::Computer Science<br />
<br />
:;Course<br />
::CPSC 432<br />
<br />
:;Description<br />
::Intermediate compiler design, with a focus on dependency resolution.<br />
<br />
:;Prereqs<br />
::CPSC 432<br />
<br />
:[The very top of the text for the next course in the table is visible but unreadable.]<br />
<br />
==Trivia==<br />
The letter code "CPSC" is the letter code Christopher Newport University, [[Randall]]'s alma mater, uses for Computer Science.<br />
<br />
{{comic discussion}}<br />
[[Category:Programming]]<br />
[[Category:Recursion]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=424:_Security_Holes&diff=164170424: Security Holes2018-10-13T15:33:28Z<p>Helloworld: /* Transcript */</p>
<hr />
<div>{{comic<br />
| number = 424<br />
| date = May 16, 2008<br />
| title = Security Holes<br />
| image = security_holes.png<br />
| titletext = True story: I had to try several times to upload this comic because my ssh key was blacklisted.<br />
}}<br />
<br />
==Explanation==<br />
The "Debian-OpenSSL fiasco" was a major security problem discovered in the {{w|Debian}} {{w|Linux distribution}} and its version of the {{w|Cryptography|cryptographic}} library called {{w|OpenSSL}}. With just a tiny change in the software, which was intended to have no effect on security, its {{w|Random number generation|random number generator}} was completely crippled, as was the security of all cryptographic keys generated by the system. The problem was created when a Debian developer removed one line of code which was crucial, even though it could seem like it did nothing useful. More detail about the fiasco: [http://trailofbits.files.wordpress.com/2008/07/hope-08-openssl.pdf ''Crippling Crypto: The Debian OpenSSL Debacle''], [http://wiki.debian.org/SSLkeys Debian's information page about the problem].<br />
<br />
The title text refers also to this issue: After the security problem was found, all cryptographic keys generated or used on the broken operating system needed to be replaced. Many systems introduced special checks for such weak keys, adding the keys to {{w|Blacklisting|blacklists}}, thereby preventing their use and forcing users to create new keys. [[Randall]] claims he was affected by that when uploading this comic to the server.<br />
<br />
The comics on the left presents Cueball as a programmer who, on a whim, removes pieces of code ([[156: Commented|commenting out]] the code by prepending the line with two slashes), presumably thinking they are not necessary. The first removed line, <code>MD_update(&m, buf, j);</code> is the exact piece of code which [http://svn.debian.org/viewsvn/pkg-openssl/openssl/trunk/rand/md_rand.c?rev=141&view=diff&r1=141&r2=140&p1=openssl/trunk/rand/md_rand.c&p2=/openssl/trunk/rand/md_rand.c was removed] in the Debian fiasco. The next panels show him commenting out fictitious lines of code apparently preventing bad things from happening.<br />
<br />
The other part of the comic lists "security problems" which were allegedly discovered in other Linux variants afterwards:<br />
<br />
Cryptographic software in {{w|Fedora Core}} was allegedly not secure against {{w|Secret decoder ring|toy decoder rings}}. <br />
<br />
{{w|Xandros}} (used in {{w|Asus Eee PC}} netbooks) gave superuser privileges to anybody "if asked in a stern voice". This is likely a reference to fact that the preinstalled Xandros OS did not require a password for root privileges by default.<br />
<br />
{{w|Gentoo}} would succumb to flattery, which may be a reference to Gentoo's notorious difficulty to manage. Any user who is capable of understanding it, might have a large ego, and therefore be susceptible to flattery.<br />
<br />
{{w|One Laptop per Child|OLPC}} OS could have been attacked using {{w|Jeff Goldblum}}'s laptop computer, which refers to a scene in the {{w|Independence Day (film)|''Independence Day'' movie}}, where Jeff Goldblum's character was able to hack into an alien spaceship using his Apple {{w|PowerBook}} computer - which is a topic of [http://www.cracked.com/article_18720_7-famous-movie-flaws-that-were-explained-in-deleted-scenes.html great contempt] by geeks who point to the absurdity of such a construction.<br />
<br />
{{w|Slackware}} gave superuser privileges to anybody who "says Elvish word for 'friend'", which refers to a scene in ''{{w|The Lord of the Rings}}'', where the entrance door to {{w|Moria}} could have been opened using a password ''mellon'', the Elvish word for "friend", as indicated on the door itself.<br />
<br />
And {{w|Ubuntu}}, which is another Linux distribution, was allegedly found to be actually {{w|Windows Vista}}, the latest version of {{w|Microsoft Windows}} at this time in 2008. This may be a reference to Ubuntu being developed with non-advanced users in mind, with many fail-safes and additional features being turned on by default, which had more in common with Windows than any other Linux-based operating system at the time.<br />
<br />
==Transcript==<br />
:[Cueball sitting at computer.]<br />
:Cueball: I'll just comment out these lines...<br />
<br />
:<code>// MD_update(&m, buf, j);</code><br />
<br />
:<code>// do_not_crash();</code><br />
<br />
:<code>// prevent_911();</code><br />
<br />
:In the rush to clean up the debian-openssl fiasco, a number of other major security holes have been uncovered:<br />
<br />
:[A two column table is shown:]<br />
<br />
:;Affected System<br />
::<b>Security problem</b><br />
<br />
----<br />
<br />
:;Fedora Core<br />
::Vulnerable to certain decoder rings<br />
<br />
:;Xandros (EEE PC)<br />
::Gives root access if asked in a stern voice<br />
<br />
:;Gentoo<br />
::Vulnerable to flattery<br />
<br />
:;OLPC OS<br />
:: Vulnerable to Jeff Goldblum’s PowerBook<br />
<br />
:;Slackware<br />
::Gives root access if user says Elvish word for “friend”<br />
<br />
:;Ubuntu<br />
::Turns out distro is actually just Windows Vista with a few custom themes<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Computers]]<br />
[[Category:Linux]]<br />
[[Category:Programming]]<br />
[[Category:LOTR]]<br />
[[Category:Cryptography]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=424:_Security_Holes&diff=164169424: Security Holes2018-10-13T12:45:55Z<p>Helloworld: /* Transcript */ Fix typos</p>
<hr />
<div>{{comic<br />
| number = 424<br />
| date = May 16, 2008<br />
| title = Security Holes<br />
| image = security_holes.png<br />
| titletext = True story: I had to try several times to upload this comic because my ssh key was blacklisted.<br />
}}<br />
<br />
==Explanation==<br />
The "Debian-OpenSSL fiasco" was a major security problem discovered in the {{w|Debian}} {{w|Linux distribution}} and its version of the {{w|Cryptography|cryptographic}} library called {{w|OpenSSL}}. With just a tiny change in the software, which was intended to have no effect on security, its {{w|Random number generation|random number generator}} was completely crippled, as was the security of all cryptographic keys generated by the system. The problem was created when a Debian developer removed one line of code which was crucial, even though it could seem like it did nothing useful. More detail about the fiasco: [http://trailofbits.files.wordpress.com/2008/07/hope-08-openssl.pdf ''Crippling Crypto: The Debian OpenSSL Debacle''], [http://wiki.debian.org/SSLkeys Debian's information page about the problem].<br />
<br />
The title text refers also to this issue: After the security problem was found, all cryptographic keys generated or used on the broken operating system needed to be replaced. Many systems introduced special checks for such weak keys, adding the keys to {{w|Blacklisting|blacklists}}, thereby preventing their use and forcing users to create new keys. [[Randall]] claims he was affected by that when uploading this comic to the server.<br />
<br />
The comics on the left presents Cueball as a programmer who, on a whim, removes pieces of code ([[156: Commented|commenting out]] the code by prepending the line with two slashes), presumably thinking they are not necessary. The first removed line, <code>MD_update(&m, buf, j);</code> is the exact piece of code which [http://svn.debian.org/viewsvn/pkg-openssl/openssl/trunk/rand/md_rand.c?rev=141&view=diff&r1=141&r2=140&p1=openssl/trunk/rand/md_rand.c&p2=/openssl/trunk/rand/md_rand.c was removed] in the Debian fiasco. The next panels show him commenting out fictitious lines of code apparently preventing bad things from happening.<br />
<br />
The other part of the comic lists "security problems" which were allegedly discovered in other Linux variants afterwards:<br />
<br />
Cryptographic software in {{w|Fedora Core}} was allegedly not secure against {{w|Secret decoder ring|toy decoder rings}}. <br />
<br />
{{w|Xandros}} (used in {{w|Asus Eee PC}} netbooks) gave superuser privileges to anybody "if asked in a stern voice". This is likely a reference to fact that the preinstalled Xandros OS did not require a password for root privileges by default.<br />
<br />
{{w|Gentoo}} would succumb to flattery, which may be a reference to Gentoo's notorious difficulty to manage. Any user who is capable of understanding it, might have a large ego, and therefore be susceptible to flattery.<br />
<br />
{{w|One Laptop per Child|OLPC}} OS could have been attacked using {{w|Jeff Goldblum}}'s laptop computer, which refers to a scene in the {{w|Independence Day (film)|''Independence Day'' movie}}, where Jeff Goldblum's character was able to hack into an alien spaceship using his Apple {{w|PowerBook}} computer - which is a topic of [http://www.cracked.com/article_18720_7-famous-movie-flaws-that-were-explained-in-deleted-scenes.html great contempt] by geeks who point to the absurdity of such a construction.<br />
<br />
{{w|Slackware}} gave superuser privileges to anybody who "says Elvish word for 'friend'", which refers to a scene in ''{{w|The Lord of the Rings}}'', where the entrance door to {{w|Moria}} could have been opened using a password ''mellon'', the Elvish word for "friend", as indicated on the door itself.<br />
<br />
And {{w|Ubuntu}}, which is another Linux distribution, was allegedly found to be actually {{w|Windows Vista}}, the latest version of {{w|Microsoft Windows}} at this time in 2008. This may be a reference to Ubuntu being developed with non-advanced users in mind, with many fail-safes and additional features being turned on by default, which had more in common with Windows than any other Linux-based operating system at the time.<br />
<br />
==Transcript==<br />
:[Cueball sitting at computer.]<br />
:Cueball: I'll just comment out these lines...<br />
<br />
:<code>// MD_update(&m, buf, j);</code><br />
<br />
:<code>// do_not_crash();</code><br />
<br />
:<code>// prevent_911();</code><br />
<br />
:In the rush to clean up the debian-openssl fiasco, a number of other major security holes have been uncovered:<br />
<br />
:[A two column table is shown:]<br />
<br />
:;Affected System<br />
::<b>Security problem</b><br />
<br />
----<br />
<br />
:;Fedora Core<br />
::Vulnerable to certain decoder rings<br />
<br />
:;Xandros (EEE PC)<br />
::Gives root access if asked in a stern voice<br />
<br />
:;Gentoo<br />
::Vulnerable to flattery<br />
<br />
:;OLPC OS<br />
:: Vulnerable to Jeff Goldblum’s PowerBook<br />
<br />
:;Slackware<br />
::Gives root access If user says Elvish word for “friend”<br />
<br />
:;Ubuntu<br />
::Turns out distro is actually just Windows Vista with a few custom themes<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Computers]]<br />
[[Category:Linux]]<br />
[[Category:Programming]]<br />
[[Category:LOTR]]<br />
[[Category:Cryptography]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&diff=1613712034: Equations2018-08-17T12:13:05Z<p>Helloworld: /* Explanation */ Looks better without allcaps</p>
<hr />
<div>{{comic<br />
| number = 2034<br />
| date = August 17, 2018<br />
| title = Equations<br />
| image = equations.png<br />
| titletext = All electromagnetic equations: The same as all fluid dynamics equations, but with the 8 and 23 replaced with the permittivity and permeability of free space, respectively.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by an EQUATION - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
This comic gives a set of equations supposedly from different areas of mathematics and physics. To anyone not familiar with the field in question they look pretty similar to what you might find in research papers or on the relevant Wikipedia pages. To someone who knows even a little about the topic, they are clearly very wrong and only seem even worse the more you look at them.<br />
{| class="wikitable"<br />
!style="width:20%"|Equation<br />
!style="width:20%"|Field<br />
!style="width:60%"|Explanation<br />
|-<br />
|<math>E = K_0t + \frac{1}{2}\rho vt^2</math><br />
|All kinematics equations<br />
|This equation literally states: "Energy equals a constant <math>K_0</math> multiplied by time, plus half of density multiplied by speed multiplied by time squared". The first term here is hard to interpret: it could be correct if <math>K_0</math> is a constant power applied to the system, but this symbol would more normally be used to denote an initial energy, in which case so multiplying by <math>t</math> would be wrong. The second term looks similar to the traditional kinetic energy formula <math>\frac{1}{2}mv^2</math> but with a density instead of the mass. This is then wrong without some accompanying volume term (on either side of the equation). This appears to be a play on the forumula: <math>s = ut + \frac{1}{2}\ at^2</math> where s (distance) travelled in a constantly accelerating environment, is determined by initial velocity (u), time (t) and acceleration (a)<br />
|-<br />
|<math>K_n = \sum_{i=0}^{\infty}\sum_{\pi=0}^{\infty}(n-\pi)(i-e^{\pi-\infty})</math><br />
|All number theory equations<br />
|Taken literally the equation says: "The nth K-number is equal to: for all i in 0 to infinity, for all pi in 0 to infinity; subtract pi from n, and multiply it with i minus e to the power of pi minus infinity". A twofold misconception can be seen here. The first is the reassignment of pi as a variable instead of the constant (3.14...). This might be a jab at how in number theory letters and numbers are used interchangeably, but where some letters are all of a sudden fixed constants. The second misconception is the use of infinity in the latter part of the formula. Naively this would signify that (with the reassigned pi values) the part in the power would range from minus infinity to zero. However, infinity is not a number and cannot be used as one without using a limit construct.<br />
|-<br />
|<math>\frac{\partial}{\partial t}\nabla\cdot \rho = \frac{8}{23}<br />
<br />
\int\!\!\!\!\!\!\!\!\!\;\;\bigcirc\!\!\!\!\!\!\!\!\!\;\;\int<br />
\rho\,ds\,dt\cdot \rho\frac{\partial}{\partial\nabla}<br />
</math><br />
|All fluid dynamic equations<br />
|Fluid dynamics describes the movement of non-solid material. In particular for gases, the density <math>\rho</math> is often the most interesting quantity (for liquids, this is actually just constant). A unique feature of fluid-dynamic equations is the presence of [https://en.wikipedia.org/wiki/Advection advection terms], which take the form of often strange-looking spatial derivatives. This equation turns this up to a new level by differentiating with respect to a differential operator <math>\nabla</math>, which does not make any sense at all. Also it has a contour integral which seems reminiscent to a closed-circle process like in a piston engine, but this does not really fit in the context (differential description of a gas), and it has a pair of [https://en.wikipedia.org/wiki/Magic_number_(programming) unexplained numbers] <math>8</math> and <math>23</math>, probably alluding to the [https://en.wikipedia.org/wiki/Heat_capacity_ratio specific heat ratio] which is often written out as the fraction <math>\tfrac{7}{5}</math>, whereas most other physics equations [https://www.explainxkcd.com/wiki/index.php/899:_Number_Line avoid including any plain numbers higher than 4].<br />
<br />
|-<br />
|<math>|\psi_{x,y}\rangle = A(\psi) A(|x\rangle \otimes |y\rangle)</math><br />
|All quantum mechanic equations<br />
|This equation takes a state psi in the dimensions of x and y and equates it to an operator A performed on psi multiplied by the same operator performed on the tensor product of x and y. Seeing as the state psi is already the tensor product of the states x and y, this is equivalent to performing the same unknown operator twice on psi, and unless this operator is its own inverse such as a bit-flip or Hermitian operator, this equation is therefore incorrect.<br />
<br />
|-<br />
|<math>\mathrm{CH}_4 + \mathrm{OH} + \mathrm{HEAT} \rightarrow \mathrm{H}_2\mathrm{O} + \mathrm{CH}_2 + \mathrm{H}_2 \mathrm{EAT}</math><br />
|All chemistry equations<br />
| A modification of the combustion of methane. The correct form is often taught and a good example problem but obviously there are more chemistry problems.<math>\mathrm{HEAT}</math> is normally shorthand for {{w|activation energy}}, but in Randall's version it's jokingly used as a chemical ingredient and becomes <math>\mathrm{H}_2\mathrm{EAT}</math>, taking the hydrogen atom freed by the combustion equation shown. To deliver the punchline while maintaining proper stoichiometry, <math>\mathrm{OH}</math> (which should be <math>\mathrm{OH}^-</math>, since the oxygen keeps a free electron when it combines with a single hydrogen) is shown instead of <math>\mathrm{O}_2</math>. The proper methane combustion equation would be: <math>\mathrm{CH}_4 + 2 \mathrm{O}_2 \rightarrow 2 \mathrm{H}_2\mathrm{O} + \mathrm{CO}_2</math><br />
|-<br />
|<math>\mathrm{SU}(2)\mathrm{U}(1) \times \mathrm{SU}(\mathrm{U}(2))</math><br />
|All quantum gravity equations<br />
|This is more similar to experessions which appear in {{w|Grand_Unified_Theory|Grand Unified Theory}} (GUT) than general quantum gravity. Unlike some of the other equations, this one has no interpretation which could make it mathematically correct. This is similar to the notations used to describe the symmetry group of a particular phenomena in terms of mathematical {{w|Lie_Group|Lie Groups}}. A real example would be the Standard Model of particle physics which has symmetry according to <math>\rm{SU(3)\times SU(2) \times U(1)}</math>. Here, <math>\rm{SU}</math> and <math>\rm{U}</math> denote the special unitary and unitary groups respectively with the numbers indicating the dimension of the group. Loosely, the three terms correspond to the symmetries of the strong force, weak force and electromagnetism although the exact correspondence is muddied by symmetry breaking and the Higgs mechanism.<br />
<br />
Of course, an expression missing an "=" sign, is difficult to interpret as an "equation", because equations normally express an "equality" of some kind. Nobody knows whether Randal refers to a horse here (equidae) <br />
<br />
Randall's version clearly involves some similar groups although without the <math>\times</math> symbol it is hard to work out what might be happening. A term like <math>\rm{SU(U(2))}</math> has no current interpretation in mathematics, if anyone thinks otherwise and possibly has a solution to the quantum gravity problem they should probably get in touch with someone about that.<br />
|-<br />
|[[File:All gauge theory equations.png]]<br />
|All gauge theory equations<br />
||This equation looks broadly similar to the sorts of things which appear in gauge theory such as the equations which define {{w|Yang–Mills_theory#Quantization|Yang-Mills Theory}}. By the time physics has got this far in, people have normally run out of regular symbols making a lot of the equations look very daunting. The actual equations in this field rarely go far beyond the Greek alphabet though and no-one has yet to try putting hats on brackets. The appearance of many sub- and superscripts is normal (this links to the group theory origins of these equations) and for the layperson it can be impossible to determine which additions are labels on the symbols and which are indices for an {{w|Einstein_notation|Einstein Sum}}.<br />
<br />
The left-hand side <math>S_g</math> is the symbol for some {{w|Action_(physics)|action}}, in Yang-Mills theory this is actually used for a so-called "ghost action". On the right-hand side we have a large number of terms, most of which are hard to interpret without knowing Randall's thought processes (this is why real research papers should all label their equations thoroughly). The <math>\frac{1}{2\bar{\varepsilon}}</math> looks like a constant of proportionality which often appears in gauge theories. The factor of <math>i = \sqrt{-1}</math> is not unusual as many of these equations use complex numbers. The <math>\eth</math> symbol looks similar to a <math>\partial</math> partial derivative symbol especially as the {{w|Dirac_equation#Covariant_form_and_relativistic_invariance|Dirac Equation}} uses a slashed version as a convenient shorthand. <br />
<br />
The rest of the equation cannot be mathematically correct as the choice of indices used does not match that on the left-hand side (which has none). In particle physics subscripts (or superscripts) of greek letters (usually <math>\mu</math> or <math>\nu</math>) indicate terms which transform nicely under Lorentz transformations (special relativity). Roman indices from the beginning of the alphabet relate to various gauge transformation propetries, the triple index seen on <math>p^{abc}_v</math> would likely come from some <math>\rm{SU(3)}</math> transformation (related to the strong nuclear force). Since <math>S_g</math> has none of these (and is thus a scalar which remains constant under these operations), we would need the right-hand side to behave in the same way. Most of the indices which appear are unpaired and so will not result in a scalar making the equation very wrong. For those not familiar with this type of equation, it is a similar mistake messing up units and setting a distance equal to a mass.<br />
|-<br />
|<math>H(t) + \Omega + G \cdot \Lambda \, \dots \begin{cases} \dots > 0 & \text{(Hubble model)} \\ \dots = 0 & \text{(Flat sphere model)} \\ \dots < 0 & \text{(Bright dark matter model)} \end{cases}<br />
</math><br />
|All cosmology equations<br />
|This is a parody of equations defining the {{w|Hubble's_law#Derivation_of_the_Hubble_parameter|Hubble Parameter}} <math>H(t)</math> although it looks like Randall has become bored and not bothered to finish his equation. Such equations usually have several <math>\Omega</math> terms representing the contributions of different substances to the energy-density of the Universe (matter, radiation, dark energy etc.). In this context <math>G</math> could be Newton's constant and <math>\Lambda</math> is something dark energy related although seeing them appear multiplied and on the same footing as <math>H</math> is unusual (the dot is entirely unnecessary). Choosing to make <math>H</math> a function of time <math>t</math> and not of redshit <math>z</math> is also unusual.<br />
<br />
The second section looks like the inequalities used to show how what shape the Universe, based on the value of the curvature parameter <math>\Omega_k</math>. A value of 0 indicates a flat Universe (this more or less what we observe) whilst a positive /negative value indicates an open /closed curved Universe. Randall's choice of labels further makes fun of the field as both a flat sphere and bright dark matter are oxymoronic terms which would involve some rather strange model universes.<br />
|-<br />
|[[File:All truly deep physics equations.png]]<br />
|All truly deep physics equations<br />
|<math>\hat H</math> is the Hamiltonian operator, which when applied to a system returns the total energy. In this context, U would usually be the potential energy. However, there is also a subscript 0 and a diacritic making indicating some other variable. Much of physics is based on Lagrangian and Hamiltonian mechanics. The Lagrangian is defined as <math>\hat L = \hat K - \hat U </math> with K being the kinetic energy and U the potential. Hamiltonian mechanics uses the equation <math>\hat H = \hat K + \hat U </math>. The Hamiltonian must be conserved so taking the time derivative and setting it equal to zero is a powerful tool. The principle of least action says allows most modern physics to be derived by setting the time derivative of the Lagrangian to zero.<br />
|}<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon. And a reminder: Do NOT use math markup in a transcript!}}<br />
:[Nine equations are listed and labeled as followed:]<br />
<br />
:E = K<sub>0</sub>t + 1/2 pvt<sup>2</sup><br />
:All kinematics equations<br />
<br />
:K<sub>n</sub> = &sum;<sub>i=0</sub><sup>&infin;</sup>&sum;<sub>&pi;=0</sub><sup>&infin;</sup>(n-&pi;)(i-e<sup>&pi;-&infin;</sup>)<br />
:All number theory equations<br />
<br />
:&#x2202;/&#x2202;t &nabla; &sdot; p = 8/23 (&#x222F; &rho; ds dt &sdot; &rho; &#x2202;/&#x2202;&nabla;)<br />
:All fluid dynamic equations<br />
<br />
:|&psi;<sub>x,y</sub>&#x232a; = A(&psi;) A(|x&#x232a;&#x2297; |y&#x232a;)<br />
:All quantum mechanic equations<br />
<br />
:CH<sub>4</sub> + OH + HEAT &rarr; H<sub>2</sub>O + CH<sub>2</sub> + H<sub>2</sub>EAT<br />
:All chemistry equations<br />
<br />
:SU(2)U(1) &times; SU(U(2))<br />
:All quantum gravity equations<br />
<br />
:S<sub>g</sub> = (-1)/(2&epsilon;&#x0304;) i &eth; (&#x302; &xi;<sub>0</sub> +&#x030a; p<sub>&epsilon;</sub> &rho;<sub>v</sub><sup>abc</sup> &eta;<sub>0</sub> )&#x302; f<sub>a</sub><sup>0</sup> &lambda;(3&#x0306;) &psi;(0<sub>a</sub>)<br />
:All gauge theory equations<br />
<br />
:H(t) + &Omega; + G&sdot;&Lambda; ... > 0 (Hubble model) ... = 0 (Flat sphere model) ... < 0 (Bright dark matter model)<br />
:All cosmology equations<br />
<br />
:&#x0124; - u&#x0327;<sub>0</sub> = 0<br />
:All truly deep physics equations<br />
<br />
{{comic discussion}}<br />
[[Category:Science]]<br />
[[Category:Math]]<br />
[[Category:Physics]]<br />
[[Category:Astronomy]]<br />
[[Category:Chemistry]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=2008:_Irony_Definition&diff=1594482008: Irony Definition2018-06-29T16:15:46Z<p>Helloworld: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 2008<br />
| date = June 18, 2018<br />
| title = Irony Definition<br />
| image = irony_definition.png<br />
| titletext = Can you stop glaring at me like that? It makes me feel really ironic.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete| the prose is terrible and unnecessary for this wiki, this does not fit the standards of our explanations, most of it is quotes from another place. It is not our job to exhaustively present the arguments around the uses of the word ironic, merely to give as much information as is needed to understand the comic. - Do NOT delete this tag too soon.}}<br />
<br />
Blackhat is deliberately using his ignorance of language to mock Cueball by stating the that it is "ironic" that he is using the word "Irony" without knowing what it means, but is still the happy one. This is both the grammatically correct use of the word "Ironic" and arguably itself an ironic situation.<br />
<br />
Cueball is depicted as annoyed, however it is unclear if it is because of the over use of the hard to define concept of irony being abused, or the meta level of this joke. <br />
<br />
The title text is contradictory in tone, clearly using "ironic" incorrectly, suggesting that the panel is infact a snapshot of a much longer conversation where Blackhat has been consistently abusing the word in an attempt to annoy Cueball.<br />
<br />
==Transcript==<br />
:[Black Hat and Cueball are walking together, with Black Hat walking behind Cueball with his arms out and palms up. Cueball is visibly upset, as evidenced by the squiggle floating above his head and his balled up fists.]<br />
:Black Hat: It's ironic how '''''you''''' know the definition of irony, yet '''''I'm''''' the one in this conversation who's happy.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Black Hat]]<br />
[[Category:Comics featuring Cueball]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=1676:_Full-Width_Justification&diff=1572891676: Full-Width Justification2018-05-19T17:23:41Z<p>Helloworld: Undo revision 157287 by 141.101.88.166 (talk) Vandalism</p>
<hr />
<div>{{comic<br />
| number = 1676<br />
| date = May 4, 2016<br />
| title = Full-Width Justification<br />
| image = full_width_justification.png<br />
| titletext = Gonna start bugging the Unicode consortium to add snake segment characters that can be combined into an arbitrary-length non-breaking snake.<br />
}}<br />
<br />
==Explanation==<br />
The comic refers to an irritating problem in laying out text to fit from margin to margin, the problem of {{w|justification (typesetting)|justification}}, where you want multiple-line text to line up on the left side (common), the right side (less common), or both sides, which is commonly called full justification. This strip is dealing with how to make text fit such that it lines up on both sides while still looking good. Sometimes, as before a long word like "[[:wikt:deindustrialization|deindustrialization]]," there's no universal good way to make the typography work. It is a difficult problem to make text look good and be easily legible especially in a narrow space, with the biggest issue being how to handle words that are too long to fit nicely.<br />
<br />
The comic shows several solutions to this problem, some realistic and others less so, but each partly or wholly unsatisfying.<br />
<br />
"'''Giving up'''" essentially means not attempting full justification for a particular line, which means it will not fit with the rest of the layout.<br />
<br />
"'''Letter spacing'''" involves an conspicuously large amount of whitespace between letters, suggesting a reading where each letter is a word until the reader recognizes what is intended. This method is in somewhat common use in newspaper and magazine layout, where it is generally known by the name "tracking" (distance between all letters) and "kerning" (distance between particular pairs of letters that fit together easily). However, letter spacing is unavailable for justification purposes in some languages (such as German), in which it is used for emphasis, as italics are in English.<br />
<br />
"'''Hyphenation'''" is confusing because it requires suspended recognition of the full word, confusing the eye into seeing, in the given case, the non-words "deindus" and "trialization". This creates difficulty in both pronouncing and parsing the word. Moreover, the decision of when and where to hyphenate is non-trivial, particularly for automated text layout; for example, breaking a word and leaving only two "orphaned" letters on the following line is generally considered an illegal hyphenation. Nevertheless, hyphenation is a very common means of handling extreme cases.<br />
<br />
"'''Stretching'''" appears visually unnatural and unfamiliar, and may present technical difficulties in rendering.<br />
<br />
Adding "'''filler'''" words is generally undesirable: in the worst case, the meaning may be unintentionally altered, or the tone might be rendered too informal, as in the given example, and even in the best case, the text becomes less concise and potentially more difficult to read. Automation is also difficult. However, filler words added by a human, especially the original author of the text, are the least visually conspicuous, and may be the most practical solution in some scenarios.<br />
<br />
Finally, adding a decorative image like "'''snakes'''" (but not necessarily snakes in particular) to fill the extra space is a justification practice of significant historical interest (it was particularly common for illuminated manuscripts in the medieval era and remained prominent until the invention of the printing press) but little modern relevance. There may be a particular absurdity to using a snake as it can be read as a word, such as "the relationship between snake deindustrialization" as would be done similar to a {{w|rebus}}.<br />
<br />
In modern text layout programs, some combination of the above strategies may be used to achieve the most visually consistent effect. For example, in one case, hyphenation might be the best option to split a very long word, while another line might be too long by only one or two letters, in which case the program could apply a very slight degree of extra letter spacing, too small for the average reader to notice.<br />
<br />
The title text suggests that in order to facilitate the "snakes" method of "solving" the problem, the {{w|Unicode Consortium}}, the organization in charge of the common text standard {{w|Unicode}}, should add "snake-building characters" (similar in concept to the existing {{w|Box Drawing}} block), to allow variable-length snake images to be used as filling. Currently, there are at least six snake characters in Unicode, not including at least ten more Egyptian hieroglyphs that represent specific snakes, some in specific combination with other hieroglyphs: [http://unicode-search.net/unicode-namesearch.pl?term=SNAKE]<br />
*[https://codepoints.net/U+1DC2 U+1DC2] &nbsp; <big>&#x1DC2;</big> &nbsp; <big>[S&#x1DC2;]</big><br />
**A diacritical {{w|combining character}} used in Americanist phonetic notation to indicate lenis (weak) articulation.<br />
*[https://codepoints.net/U+2E92 U+2E92] &nbsp; <big>&#x2E92;</big><br />
**A {{w|CJK character}} which might be interpreted as "snake".<br />
*[https://codepoints.net/U+8675 U+8675] &nbsp; <big>&#x8675;</big><br />
**Another CJK character meaning "snake".<br />
*[https://codepoints.net/U+86C7 U+86C7] &nbsp; <big>&#x86C7;</big><br />
**Another CJK character meaning "snake".<br />
*[https://codepoints.net/U+1D9DC U+1D9DC] &nbsp; <big>&#x1D9DC;</big><br />
**One of the poorly-supported characters in the {{w|signWriting|signwriting block}}.<br />
*[https://codepoints.net/U+1F40D U+1F40D] &nbsp; <big>&#x1F40D;</big><br />
**An {{w|emoji}} snake.<br />
<br />
One of the hieroglyphs ([https://codepoints.net/U+13192 U+13192 EGYPTIAN HIEROGLYPH I009A]) is described in [https://mjn.host.cs.st-andrews.ac.uk/egyptian/unicode/tablemain.html source documents] as HORNED VIPER CRAWLING OUT OF ENCLOSURE, so it is literally a snake-building character.<br />
<br />
"Non-breaking" in the title text refers to a similar process as zero-width joiners and no-break HTML and CSS; the whole snake would shift down if it were too wide to fit on a given line. This suggestion would likely be rejected; the Unicode consortium is very specific about which characters are added{{Citation needed}}, and always require a good reason{{Citation needed}} before adding a character or set of characters to the standard. Strange decisions by the consortium have previously been referenced in [[1253: Exoplanet Names]], [[1513: Code Quality]], and [[1525: Emojic 8 Ball]].<br />
<br />
Within an hour or two of this comic being published, a thread on the subject started on the Unicode Consortium’s official Unicode Mailing List. As of two days later, it’s still running.<br />
<br />
==Transcript==<br />
:Strategies for full-width justification<br />
<br />
:[Below the caption is a column with six boxes, each showing a different "strategy" for justification which is annotated beside it. Here the annotation is written at the top and the text below. The top and bottom of the text is cut of in the middle, but as it can be "read" this is written anyway. Only for hyphenation does an extra word appear at the end. In the last with snakes, a snake is drawn to cover the entire space from the end of between to the right border.]<br />
<br />
:Giving up<br />
::their famous paper<br />
::on the relationship<br />
::between<br />
::deindustrialization<br />
::and the growth of<br />
<br />
:Letter spacing<br />
::their famous paper<br />
::on the relationship<br />
::b &nbsp;e &nbsp; t &nbsp; w &nbsp; e&nbsp; e &nbsp; n<br />
::deindustrialization<br />
::and the growth of<br />
<br />
:Hyphenation<br />
::their famous paper<br />
::on the relationship<br />
::between deindus-<br />
::trialization and the<br />
::growth of ecological<br />
<br />
:Stretching<br />
::their famous paper<br />
::on the relationship<br />
::<big><big><big>between</big></big></big><br />
::deindustrialization<br />
::and the growth of<br />
<br />
:Filler<br />
::their famous paper<br />
::on the relationship<br />
::between crap like<br />
::deindustrialization<br />
::and the growth of<br />
<br />
:Snakes<br />
::their famous paper<br />
::on the relationship<br />
::between 🐍 [a snake filling the gap]<br />
::deindustrialization<br />
::and the growth of<br />
<br />
==Trivia==<br />
*The full text (with alternate changes) reads:<br />
::''...their famous paper on the relationship between [crap like]/[ 🐍 ] deindustrialization and the growth of [ecological]...''<br />
*An approach not depicted is to treat justification as part of a global typesetting strategy which allows words to move between lines even where this is not locally optimal. Its net effect in a case like this is to pull words from the previous line for use as filler. This approach is used by {{w|TeX}}.<br />
*In Arabic, it is common to stretch the lines connecting letters as a relatively elegant and satisfying resolution to this problem. This trick is called "{{w|kashida}}" (كشيدة). There does in fact exist a Unicode character, U+0640: (ـ), to help with this: using it to extend "كشيدة" would result in something like "كـــــشـــيـــدة" (which, incidentally, looks a lot like a snake).<br />
*Jim Chapman, developer of Windows 10 e-reader app Freda, has implemented snake-justification in the app, now available on the [https://www.microsoft.com/store/apps/9wzdncrfj43b Windows Store]. For best results, use the 'settings' screen to switch 'hyphenation' to 'no', 'use snakes' to 'yes', and choose a large font size (33 or so). Then pick a book with long words and justified text, and read it in a narrow window.<br />
*The comic has been discussed on the [http://www.unicode.org/mail-arch/unicode-ml/y2016-m05/0004.html Unicode Mailing List].<br />
*The typesetting system [http://www.sile-typesetter.org/ SILE] implemented snake justification on the same day the comic was published.<br />
*"Line Fillers" depicting animals (including snakes) were widely used in [http://www.medievalcodes.ca/2016/04/line-fillers.html medieval book art].<br />
<br />
{{comic discussion}}<br />
[[Category:Animals]]<br />
[[Category:Unicode]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=404:_Not_Found&diff=154534404: Not Found2018-03-19T17:24:06Z<p>Helloworld: Added transcript; Randall considers it an actual comic</p>
<hr />
<div>{{comic<br />
| number = 404<br />
| date = April 1, 2008<br />
| title = Not Found<br />
| image = not found.png<br />
}}<br />
<br />
==Explanation==<br />
There is no xkcd comic numbered 404. Randall did not skip a day, however; he put [[405: Journal 3|405]] up on April 2 (2008), which leads some to see the 404 as an April Fool's joke.<br />
<br />
"404" is the HTTP Response Code for "{{w|HTTP 404|Not Found}}". [[Randall]] deliberately skipped comic number 404 in xkcd. Therefore, when people go to {{xkcd|404}} they get a "404 Not Found" error page. (This does not work in all browsers. In newer versions of Internet Explorer a message about the link being broken occurs without the 404 code.)<br />
<br />
[[Randall]] has stated that he considers 404 [http://plus.google.com/111588569124648292310/posts/j6w9DkYApya an official, actual comic, albeit a rather avant-garde one], and that for a time he made it possible to find it using the "random" button on xkcd.com.<br />
<br />
It may seem like a random coincidence that {{xkcd|403}} came out the day before April 1st 2008. And for sure it must have been by chance that it would come out close to that date when Randall began posting on xkcd. But when Randall noticed this fact, at some point prior to that date, he would, however, have had a chance to influence the release date. In November 2007, less than half a year before this April 1st, he released the [[:Category:1337|1337 series]] over five consecutive days. That would have moved the release date of 403 from Friday the 4th of April to the Monday it was actually released - making it possible to skip comic 404 as if it came out on April 1st without skipping a comic on a normal release day. There was at least one other series in 2007 to use all five days of a week ([[:Category:Choices|Choices]]), so maybe he had this planned for a long time?<br />
<br />
It is perhaps an interesting point that the very next comic, {{xkcd|405}} includes the line "So, you found me after all."<br />
<br />
==Transcript==<br />
:<big><big><span style="font-family:timesnewroman;">'''404 Not Found'''</span></big></big><br />
<br />
<div style="border-bottom: 1px solid #000000"></div><br />
<br />
:::<span style="font-family:timesnewroman">nginx</span><br />
<br />
==Trivia==<br />
*The web comic Comic JK made this spoof of this missing comic in total xkcd style:<br />
**The [https://web.archive.org/web/20100925103935/http://comicjk.com/comic.php/404 comic 404] that could have been.<br />
<br />
{{comic discussion}}<br />
[[Category:April fools' comics]]<br />
[[Category:No title text]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=1923:_Felsius&diff=1486221923: Felsius2017-12-02T00:57:18Z<p>Helloworld: /* Implementations */ Added more details how it works after seeing it on reddit</p>
<hr />
<div>{{comic<br />
| number = 1923<br />
| date = December 1, 2017<br />
| title = Felsius<br />
| image = felsius.png<br />
| titletext = The symbol for degrees Felsius is an average of the Euro symbol (&#8364;) and the Greek lunate epsilon (&#1013;).<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Explanation seems fine but maybe some comment on why the chosen labels is not very relevant for a temperature scale . Fahrenheit 0 is not interesting for instance compared to 0 Celsius. Brief mention in explanation and a new column with notes in the table.}}<br />
<br />
Just like in [[1292: Pi vs. Tau]], [[Randall]] tries to unify two measurement systems by averaging both values, assumably with little success.<br />
<br />
There are several {{w|Scale_of_temperature|temperature scales}} actively used in different parts of the world of for different purposes, including {{w|Celsius}} and {{w|Fahrenheit}}, but e.g. also {{w|Kelvin}} and {{w|Rankine_scale|Rankine}}.<br />
<br />
The debate on whether to use Fahrenheit or Celsius is, just like the one between {{w|Imperial_units|imperial}} and {{w|Metric system|metric}} units, one that is mostly restricted to the US. Most other countries have already switched from Fahrenheit to Celsius or have always used Celsius. In scientific circles, even in the US, only Celsius (and Kelvin) are used.<br />
<br />
The conversion factors between Celsius and Fahrenheit are:<br />
:°C = (°F − 32) * 5 / 9<br />
:°F = °C * 9 / 5 + 32<br />
<br />
which indeed make the average value of °C and °F:<br />
:°ϵ = °C * 7 / 5 + 16 = (°F * 7 - 80) / 9<br />
<br />
[[Randall]] choose to name his new unit of temperature Felsius (a {{w|portmanteau}} of Fahrenheit and Celsius).<br />
<br />
The title text states that the symbol he chose to represent this unit also is the average of two other symbols. Visually, it is assumed to be a combination of Celsius and Fahrenheit (a C with a crossbar), but it is actually the unrelated symbols for the {{w|Euro sign|euro}} (€) and the Greek lunate {{w|epsilon}} (ϵ). We have used the latter (which, like Randall's symbol and unlike the Euro symbol, has a single crossbar) in this explanation and transcript, but the crossbar in the symbol as actually drawn by Randall continues to the left (like the Euro symbol and unlike the lunate Epsilon).<br />
<br />
{|class="wikitable"<br />
!Symbol!!Number of crossbars!!Length of crossbar(s)<br />
|-<br />
||Euro||2||Long<br />
|-<br />
||Epsilon||1||Short<br />
|-<br />
||Felsius||1||Long<br />
|-<br />
||[not used]||2||Short<br />
|}<br />
<br />
In doing all this, Randall has fallen into the trap of creating a new temperature scale/standard: see [[927|927: Standards]].<br />
<br />
Randall has also compared Celsius and Fahrenheit scales earlier in [[1643: Degrees]].<br />
<br />
=== Table of Given Conversions & Additional ===<br />
{| class="wikitable"<br />
!°ϵ!!°C!!°F!!Note<br />
|-<br />
| style="text-align:right;" |156.0<br />
| style="text-align:right;" |100.0<br />
| style="text-align:right;" |211.9<br />
||Water boils at sea level (1 atmosphere)<br />
|-<br />
| style="text-align:right;" |91.6<br />
| style="text-align:right;" |54.0<br />
| style="text-align:right;" |129.2<br />
||World heat record (per [https://en.wikipedia.org/wiki/Highest_temperature_recorded_on_Earth Wikipedia])<br />
|-<br />
| style="text-align:right;" |67.8<br />
| style="text-align:right;" |37.0<br />
| style="text-align:right;" |98.6<br />
||Body temperature (accepted average)<br />
|-<br />
| style="text-align:right;" |46.8<br />
| style="text-align:right;" |22.0<br />
| style="text-align:right;" |71.6<br />
||Room temperature (maximum per [https://ahdictionary.com/word/search.html?q=room+temperature American Heritage Dictionary])<br />
|-<br />
| style="text-align:right;" |16.0<br />
| style="text-align:right;" |0.0<br />
| style="text-align:right;" |32.0<br />
||Water freezes on Earth (1 atmosphere); 0°C reference<br />
|-<br />
| style="text-align:right;" |0.0<br />
| style="text-align:right;" |−11.4<br />
| style="text-align:right;" |11.4<br />
||0°ϵ reference<br />
|-<br />
| style="text-align:right;" |−8.9<br />
| style="text-align:right;" |−17.8<br />
| style="text-align:right;" |0.0<br />
||0°F reference<br />
|-<br />
| style="text-align:right;" |−40.0<br />
| style="text-align:right;" |−40.0<br />
| style="text-align:right;" |−40.0<br />
||Equivalence point (exactly −40)<br />
|-<br />
| style="text-align:right;" |−366.4<br />
| style="text-align:right;" |−273.2<br />
| style="text-align:right;" |−459.7<br />
||Absolute zero (exactly −273.15°C)<br />
|}<br />
<br />
==Transcript==<br />
:[A thermometer is shown where the temperature is indicated, with a red column of liquid, to be just above room temperature. This can be seen from the five labels belonging to five lines pointing at the scale. None of these coincide with the 14 ticks on the actual scale for the thermometer. Below the last label is the formula for calculating the temperature on this scale.]<br />
:92°ϵ world heat record<br />
:68°ϵ body temperature<br />
:47°ϵ room temperature<br />
:16°ϵ water freezes<br />
:–9°ϵ 0°F<br />
:°ϵ=7×°C/5+16=(7×°F–80)/9<br />
<br />
<br />
:[Caption below the panel:]<br />
:Since the Celsius vs Fahrenheit debate has proven surprisingly hard to resolve, as a compromise I've started using Felsius (°ϵ), the average of the two.<br />
<br />
<br />
==Implementations==<br />
An implementation of Felsius is available at [http://www.weatherinfelsius.us Weather In Felsius], using a location based on user's IP address and accepting US ZIP codes.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics with color]]<br />
[[Category:Portmanteau]]<br />
[[Category:Math]]<br />
[[Category:Physics]]<br />
[[Category:Compromise]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=1923:_Felsius&diff=1486211923: Felsius2017-12-02T00:54:20Z<p>Helloworld: Nvm, removing own request</p>
<hr />
<div>{{comic<br />
| number = 1923<br />
| date = December 1, 2017<br />
| title = Felsius<br />
| image = felsius.png<br />
| titletext = The symbol for degrees Felsius is an average of the Euro symbol (&#8364;) and the Greek lunate epsilon (&#1013;).<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Explanation seems fine but maybe some comment on why the chosen labels is not very relevant for a temperature scale . Fahrenheit 0 is not interesting for instance compared to 0 Celsius. Brief mention in explanation and a new column with notes in the table.}}<br />
<br />
Just like in [[1292: Pi vs. Tau]], [[Randall]] tries to unify two measurement systems by averaging both values, assumably with little success.<br />
<br />
There are several {{w|Scale_of_temperature|temperature scales}} actively used in different parts of the world of for different purposes, including {{w|Celsius}} and {{w|Fahrenheit}}, but e.g. also {{w|Kelvin}} and {{w|Rankine_scale|Rankine}}.<br />
<br />
The debate on whether to use Fahrenheit or Celsius is, just like the one between {{w|Imperial_units|imperial}} and {{w|Metric system|metric}} units, one that is mostly restricted to the US. Most other countries have already switched from Fahrenheit to Celsius or have always used Celsius. In scientific circles, even in the US, only Celsius (and Kelvin) are used.<br />
<br />
The conversion factors between Celsius and Fahrenheit are:<br />
:°C = (°F − 32) * 5 / 9<br />
:°F = °C * 9 / 5 + 32<br />
<br />
which indeed make the average value of °C and °F:<br />
:°ϵ = °C * 7 / 5 + 16 = (°F * 7 - 80) / 9<br />
<br />
[[Randall]] choose to name his new unit of temperature Felsius (a {{w|portmanteau}} of Fahrenheit and Celsius).<br />
<br />
The title text states that the symbol he chose to represent this unit also is the average of two other symbols. Visually, it is assumed to be a combination of Celsius and Fahrenheit (a C with a crossbar), but it is actually the unrelated symbols for the {{w|Euro sign|euro}} (€) and the Greek lunate {{w|epsilon}} (ϵ). We have used the latter (which, like Randall's symbol and unlike the Euro symbol, has a single crossbar) in this explanation and transcript, but the crossbar in the symbol as actually drawn by Randall continues to the left (like the Euro symbol and unlike the lunate Epsilon).<br />
<br />
{|class="wikitable"<br />
!Symbol!!Number of crossbars!!Length of crossbar(s)<br />
|-<br />
||Euro||2||Long<br />
|-<br />
||Epsilon||1||Short<br />
|-<br />
||Felsius||1||Long<br />
|-<br />
||[not used]||2||Short<br />
|}<br />
<br />
In doing all this, Randall has fallen into the trap of creating a new temperature scale/standard: see [[927|927: Standards]].<br />
<br />
Randall has also compared Celsius and Fahrenheit scales earlier in [[1643: Degrees]].<br />
<br />
=== Table of Given Conversions & Additional ===<br />
{| class="wikitable"<br />
!°ϵ!!°C!!°F!!Note<br />
|-<br />
| style="text-align:right;" |156.0<br />
| style="text-align:right;" |100.0<br />
| style="text-align:right;" |211.9<br />
||Water boils at sea level (1 atmosphere)<br />
|-<br />
| style="text-align:right;" |91.6<br />
| style="text-align:right;" |54.0<br />
| style="text-align:right;" |129.2<br />
||World heat record (per [https://en.wikipedia.org/wiki/Highest_temperature_recorded_on_Earth Wikipedia])<br />
|-<br />
| style="text-align:right;" |67.8<br />
| style="text-align:right;" |37.0<br />
| style="text-align:right;" |98.6<br />
||Body temperature (accepted average)<br />
|-<br />
| style="text-align:right;" |46.8<br />
| style="text-align:right;" |22.0<br />
| style="text-align:right;" |71.6<br />
||Room temperature (maximum per [https://ahdictionary.com/word/search.html?q=room+temperature American Heritage Dictionary])<br />
|-<br />
| style="text-align:right;" |16.0<br />
| style="text-align:right;" |0.0<br />
| style="text-align:right;" |32.0<br />
||Water freezes on Earth (1 atmosphere); 0°C reference<br />
|-<br />
| style="text-align:right;" |0.0<br />
| style="text-align:right;" |−11.4<br />
| style="text-align:right;" |11.4<br />
||0°ϵ reference<br />
|-<br />
| style="text-align:right;" |−8.9<br />
| style="text-align:right;" |−17.8<br />
| style="text-align:right;" |0.0<br />
||0°F reference<br />
|-<br />
| style="text-align:right;" |−40.0<br />
| style="text-align:right;" |−40.0<br />
| style="text-align:right;" |−40.0<br />
||Equivalence point (exactly −40)<br />
|-<br />
| style="text-align:right;" |−366.4<br />
| style="text-align:right;" |−273.2<br />
| style="text-align:right;" |−459.7<br />
||Absolute zero (exactly −273.15°C)<br />
|}<br />
<br />
==Transcript==<br />
:[A thermometer is shown where the temperature is indicated, with a red column of liquid, to be just above room temperature. This can be seen from the five labels belonging to five lines pointing at the scale. None of these coincide with the 14 ticks on the actual scale for the thermometer. Below the last label is the formula for calculating the temperature on this scale.]<br />
:92°ϵ world heat record<br />
:68°ϵ body temperature<br />
:47°ϵ room temperature<br />
:16°ϵ water freezes<br />
:–9°ϵ 0°F<br />
:°ϵ=7×°C/5+16=(7×°F–80)/9<br />
<br />
<br />
:[Caption below the panel:]<br />
:Since the Celsius vs Fahrenheit debate has proven surprisingly hard to resolve, as a compromise I've started using Felsius (°ϵ), the average of the two.<br />
<br />
<br />
==Implementations==<br />
An implementation of Felsius is available at [http://www.weatherinfelsius.us Weather In Felsius].<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics with color]]<br />
[[Category:Portmanteau]]<br />
[[Category:Math]]<br />
[[Category:Physics]]<br />
[[Category:Compromise]]</div>Helloworldhttps://www.explainxkcd.com/wiki/index.php?title=1923:_Felsius&diff=1486151923: Felsius2017-12-01T23:52:38Z<p>Helloworld: Added an incomplete reason related to implementations</p>
<hr />
<div>{{comic<br />
| number = 1923<br />
| date = December 1, 2017<br />
| title = Felsius<br />
| image = felsius.png<br />
| titletext = The symbol for degrees Felsius is an average of the Euro symbol (&#8364;) and the Greek lunate epsilon (&#1013;).<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Explanation seems fine but maybe some comment on why the chosen labels is not very relevant for a temperature scale . Fahrenheit 0 is not interesting for instance compared to 0 Celsius. Brief mention in explanation and a new column with notes in the table.<br />
''Also, if there should be a link to a Felsius weather implementation, preferably it should not rely on US ZIP codes only.''<br />
}}<br />
<br />
Just like in [[1292: Pi vs. Tau]], [[Randall]] tries to unify two measurement systems by averaging both values, assumably with little success.<br />
<br />
There are several {{w|Scale_of_temperature|temperature scales}} actively used in different parts of the world of for different purposes, including {{w|Celsius}} and {{w|Fahrenheit}}, but e.g. also {{w|Kelvin}} and {{w|Rankine_scale|Rankine}}.<br />
<br />
The debate on whether to use Fahrenheit or Celsius is, just like the one between {{w|Imperial_units|imperial}} and {{w|Metric system|metric}} units, one that is mostly restricted to the US. Most other countries have already switched from Fahrenheit to Celsius or have always used Celsius. In scientific circles, even in the US, only Celsius (and Kelvin) are used.<br />
<br />
The conversion factors between Celsius and Fahrenheit are:<br />
:°C = (°F − 32) * 5 / 9<br />
:°F = °C * 9 / 5 + 32<br />
<br />
which indeed make the average value of °C and °F:<br />
:°ϵ = °C * 7 / 5 + 16 = (°F * 7 - 80) / 9<br />
<br />
[[Randall]] choose to name his new unit of temperature Felsius (a {{w|portmanteau}} of Fahrenheit and Celsius).<br />
<br />
The title text states that the symbol he chose to represent this unit also is the average of two other symbols. Visually, it is assumed to be a combination of Celsius and Fahrenheit (a C with a crossbar), but it is actually the unrelated symbols for the {{w|Euro sign|euro}} (€) and the Greek lunate {{w|epsilon}} (ϵ). We have used the latter (which, like Randall's symbol and unlike the Euro symbol, has a single crossbar) in this explanation and transcript, but the crossbar in the symbol as actually drawn by Randall continues to the left (like the Euro symbol and unlike the lunate Epsilon).<br />
<br />
{|class="wikitable"<br />
!Symbol!!Number of crossbars!!Length of crossbar(s)<br />
|-<br />
||Euro||2||Long<br />
|-<br />
||Epsilon||1||Short<br />
|-<br />
||Felsius||1||Long<br />
|-<br />
||[not used]||2||Short<br />
|}<br />
<br />
In doing all this, Randall has fallen into the trap of creating a new temperature scale/standard: see [[927|927: Standards]].<br />
<br />
Randall has also compared Celsius and Fahrenheit scales earlier in [[1643: Degrees]].<br />
<br />
=== Table of Given Conversions & Additional ===<br />
{| class="wikitable"<br />
!°ϵ!!°C!!°F!!Note<br />
|-<br />
| style="text-align:right;" |156.0<br />
| style="text-align:right;" |100.0<br />
| style="text-align:right;" |211.9<br />
||Water boils at sea level (1 atmosphere)<br />
|-<br />
| style="text-align:right;" |91.6<br />
| style="text-align:right;" |54.0<br />
| style="text-align:right;" |129.2<br />
||World heat record (per [https://en.wikipedia.org/wiki/Highest_temperature_recorded_on_Earth Wikipedia])<br />
|-<br />
| style="text-align:right;" |67.8<br />
| style="text-align:right;" |37.0<br />
| style="text-align:right;" |98.6<br />
||Body temperature (accepted average)<br />
|-<br />
| style="text-align:right;" |46.8<br />
| style="text-align:right;" |22.0<br />
| style="text-align:right;" |71.6<br />
||Room temperature (maximum per [https://ahdictionary.com/word/search.html?q=room+temperature American Heritage Dictionary])<br />
|-<br />
| style="text-align:right;" |16.0<br />
| style="text-align:right;" |0.0<br />
| style="text-align:right;" |32.0<br />
||Water freezes on Earth (1 atmosphere); 0°C reference<br />
|-<br />
| style="text-align:right;" |0.0<br />
| style="text-align:right;" |−11.4<br />
| style="text-align:right;" |11.4<br />
||0°ϵ reference<br />
|-<br />
| style="text-align:right;" |−8.9<br />
| style="text-align:right;" |−17.8<br />
| style="text-align:right;" |0.0<br />
||0°F reference<br />
|-<br />
| style="text-align:right;" |−40.0<br />
| style="text-align:right;" |−40.0<br />
| style="text-align:right;" |−40.0<br />
||Equivalence point (exactly −40)<br />
|-<br />
| style="text-align:right;" |−366.4<br />
| style="text-align:right;" |−273.2<br />
| style="text-align:right;" |−459.7<br />
||Absolute zero (exactly −273.15°C)<br />
|}<br />
<br />
==Transcript==<br />
:[A thermometer is shown where the temperature is indicated, with a red column of liquid, to be just above room temperature. This can be seen from the five labels belonging to five lines pointing at the scale. None of these coincide with the 14 ticks on the actual scale for the thermometer. Below the last label is the formula for calculating the temperature on this scale.]<br />
:92°ϵ world heat record<br />
:68°ϵ body temperature<br />
:47°ϵ room temperature<br />
:16°ϵ water freezes<br />
:–9°ϵ 0°F<br />
:°ϵ=7×°C/5+16=(7×°F–80)/9<br />
<br />
<br />
:[Caption below the panel:]<br />
:Since the Celsius vs Fahrenheit debate has proven surprisingly hard to resolve, as a compromise I've started using Felsius (°ϵ), the average of the two.<br />
<br />
<br />
==Implementations==<br />
An implementation of Felsius is available at [http://www.weatherinfelsius.us Weather In Felsius].<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics with color]]<br />
[[Category:Portmanteau]]<br />
[[Category:Math]]<br />
[[Category:Physics]]<br />
[[Category:Compromise]]</div>Helloworld