https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=173.245.54.190&feedformat=atomexplain xkcd - User contributions [en]2024-03-29T12:57:50ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=1313:_Regex_Golf&diff=889561313: Regex Golf2015-04-08T01:31:45Z<p>173.245.54.190: /* Regular expressions */</p>
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<div>{{comic<br />
| number = 1313<br />
| date = January 6, 2014<br />
| title = Regex Golf<br />
| image = regex_golf.png<br />
| titletext = <nowiki>/bu|[rn]t|[coy]e|[mtg]a|j|iso|n[hl]|[ae]d|lev|sh|[lnd]i|[po]o|ls/ matches the last names of elected US presidents but not their opponents.</nowiki><br />
}}<br />
<br />
==Explanation==<br />
The comic talks about {{w|regular expressions}}, which are a way to specify textual patterns. Given a regular expression, one can search for the pattern it specifies inside a text string. If the pattern is found, it's said that the pattern "matches" the string; if it's not found, it's said they do not match.<br />
<br />
The title of the comic and the first panel is based on "[http://regex.alf.nu/ regex golf]", which is a discipline of "{{w|code golf}}", a game in which programmers attempt to solve a given programming problem using as few characters as possible, analogous to the number of {{w|golf}} shots it takes to reach the goal. In regex golfing, the programmer is given two sets of text fragments, and he/she tries to write the shortest possible regular expression which would match all elements of one set, while at the same time not matching any element from the other set.<br />
<br />
The regex golf challenge Megan faces consists of matching all subtitles of ''{{w|Star Wars}}'' episodes, while not matching any subtitle of ''{{w|Star Trek}}'' episodes. {{w|Subtitle (titling)|Subtitles}} are the secondary titles of the movies, after the ''"Star Trek: "'' or ''"Star Wars Episode N: "''. For example, in ''Star Wars Episode I: The Phantom Menace'', the subtitle is ''The Phantom Menace''. In the first panel, she created a 12-character regex solving the challenge.<br />
<br />
Then she moved on to building a tool which would automatically build such a regex for arbitrary lists of text, which could be described as {{w|meta}}- regex golfing. But as she has lost this tool, she needs to search through her files and chooses a tool called "{{w|grep}}" to find it. This implies that she needs a regular expression that would find any code that appears to be a regex golf generator, which leads to another "meta-" layer of abstraction. At the end, Megan notes this sequence of meta-meta-... might go to infinity and Cueball quips that she now has "infinite problems" as a result of her efforts; Megan retorts that she already had "infinite problems" because she's geeky enough to run meta-versions of programs on themselves, and stubborn enough to continue on until she fails, to the exclusion of all else. This also seems to be a reference to a famous quote (see also ''[[1171: Perl Problems]]''):<br />
<br />
<blockquote>''Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems.''</blockquote><br />
<br />
===Regular expressions===<br />
The first regex Megan uses is <code>/m | [tn]|b/</code>, said to match ''Star Wars'' subtitles but not ''Star Trek''.<br />
<br />
The forward slashes <code>/</code> just mark the start and end of the regex. The <code>|</code> character means "or", so the regex matches any string that contains the patterns "<code>m </code>", "<code> [tn]</code>" or "<code>b</code>" (including the spaces). The square brackets match one of the enclosed characters, meaning that "<code> [tn]</code>" matches either "<code> t</code>" or "<code> n</code>". The regex is apparently case-insensitive, because it wouldn't work otherwise.<br />
<br />
The Star Wars subtitles match the parts of the regex in the following way:<br />
*"The Phanto<u>m </u>Menace" is matched by "<code>m </code>".<br />
*"Attack of<u> t</u>he Clones" is matched by "<code> [tn]</code>".<br />
*"Revenge of<u> t</u>he Sith" is matched by "<code> [tn]</code>".<br />
*"A<u> N</u>ew Hope" is matched by "<code> [tn]</code>".<br />
*"The Empire Strikes <u>B</u>ack" is matched by "<code>b</code>".<br />
*"Return of<u> t</u>he Jedi" is matched by "<code> [tn]</code>".<br />
Note that if one included the animated film "Star Wars: The Clone Wars" it would not be matched by "<code> [tn]</code>" because the T is the start of the subtitle and is not preceded by a space.<br />
<br />
On the other hand, none of the Star Trek subtitles contains an M followed by a space, a T or an N preceded by a space, or any B, so the regex does not match any of them. Note that in the original series all subtitles start with a "T" but it's the first character so it's not preceded by a space.<br />
<br />
Here is the list that Megan probably used:<br />
*Original series:<br />
**The Motion Picture<br />
**The Wrath of Khan<br />
**The Search For Spock<br />
**The Voyage Home<br />
**The Final Frontier<br />
**The Undiscovered Country<br />
*The Next Generation:<br />
**Generations<br />
**First Contact<br />
**Insurrection<br />
**Nemesis<br />
*Reboot series:<br />
**''the one without a subtitle''<br />
**Into Darkness<br />
<br />
In the last panel "and beyond" Megan uses the regular expression <code>/(meta-)*regex golf/</code> to describe her problem. <code>*</code> means "zero or more" of the preceding character/group (parentheses <code>()</code> group characters). So this regex matches "regex golf", "meta-regex golf", "meta-meta-regex golf", etc. In a way this is regex golf in itself, matching all levels of meta-regex golf while not matching anything else.<br />
<br />
In the title text, there is a long regex that is the solution of another regex golf challenge: matching the last names of all elected US presidents but not their opponents. Note that the list of opponents include some people who were previously or later became presidents, so taken literally this is impossible. To make this work the list of opponents must exclude anyone who was also president. The regular expression itself works in a very similar way to the Star Wars/Trek one, including several different patterns separated by <code>|</code>. Each elected president matches one pattern while each opponent matches none.<br />
<br />
Here is a list of elected president and the patterns they match:<br />
{| class="wikitable"<br />
!Number<br />
!President<br />
!Matched expression<br />
|-<br />
|1<br />
|{{w|George Washington|George Wa<u>sh</u>ington}}<br />
|<code>sh</code><br />
|-<br />
|2<br />
|{{w|John Adams|John <u>Ad</u>ams}}<br />
|<code>[ae]d</code><br />
|-<br />
|3<br />
|{{w|Thomas Jefferson|Thomas <u>J</u>efferson}}<br />
|<code>j</code><br />
|-<br />
|4<br />
|{{w|James Madison|James <u>Ma</u>dison}}<br />
|<code>[mtg]a</code><br />
|-<br />
|5<br />
|{{w|James Monroe|James Monr<u>oe</u>}}<br />
|<code>[coy]e</code><br />
|-<br />
|6<br />
|{{w|John Quincy Adams|John Quincy <u>Ad</u>ams}}<br />
|<code>[ae]d</code><br />
|-<br />
|7<br />
|{{w|Andrew Jackson|Andrew <u>J</u>ackson}}<br />
|<code>j</code><br />
|-<br />
|8<br />
|{{w|Martin Van Buren|Martin Van <u>Bu</u>ren}}<br />
|<code>bu</code><br />
|-<br />
|9<br />
|{{w|William Henry Harrison|William Henry Harr<u>iso</u>n}}<br />
|<code>iso</code><br />
|-<br />
|11<br />
|{{w|James K. Polk|James K. <u>Po</u>lk}}<br />
|<code>[po]o</code><br />
|-<br />
|12<br />
|{{w|Zachary Taylor|Zachary <u>Ta</u>ylor}}<br />
|<code>[mtg]a</code><br />
|-<br />
|14<br />
|{{w|Franklin Pierce|Franklin Pier<u>ce</u>}}<br />
|<code>[coy]e</code><br />
|-<br />
|15<br />
|{{w|James Buchanan|James <u>Bu</u>chanan}}<br />
|<code>bu</code><br />
|-<br />
|16<br />
|{{w|Abraham Lincoln|Abraham <u>Li</u>ncoln}}<br />
|<code>[lnd]i</code><br />
|-<br />
|17<br />
|{{w|Andrew Johnson|Andrew <u>J</u>ohnson}}<br />
|<code>j</code><br />
|-<br />
|18<br />
|{{w|Ulysses S. Grant|Ulysses S. Gra<u>nt</u>}}<br />
|<code>[rn]t</code><br />
|-<br />
|19<br />
|{{w|Rutherford B. Hayes|Rutherford B. Ha<u>ye</u>s}}<br />
|<code>[coy]e</code><br />
|-<br />
|20<br />
|{{w|James A. Garfield|James A. <u>Ga</u>rfield}}<br />
|<code>[mtg]a</code><br />
|-<br />
|22<br />
|{{w|Grover Cleveland|Grover C<u>lev</u>eland}}<br />
|<code>lev</code><br />
|-<br />
|23<br />
|{{w|Benjamin Harrison|Benjamin Harr<u>iso</u>n}}<br />
|<code>iso</code><br />
|-<br />
|24<br />
|{{w|Grover Cleveland|Grover C<u>lev</u>eland}}<br />
|<code>lev</code><br />
|-<br />
|25<br />
|{{w|William McKinley|William McKi<u>nl</u>ey}}<br />
|<code>n[hl]</code><br />
|-<br />
|26<br />
|{{w|Theodore Roosevelt|Theodore R<u>oo</u>sevelt}}<br />
|<code>[po]o</code><br />
|-<br />
|27<br />
|{{w|William Howard Taft|William Howard <u>Ta</u>ft}}<br />
|<code>[mtg]a</code><br />
|-<br />
|28<br />
|{{w|Woodrow Wilson|Woodrow Wi<u>ls</u>on}}<br />
|<code>ls</code><br />
|-<br />
|29<br />
|{{w|Warren G. Harding|Warren G. Har<u>di</u>ng}}<br />
|<code>[lnd]i</code><br />
|-<br />
|30<br />
|{{w|Calvin Coolidge|Calvin Coo<u>li</u>dge}}<br />
|<code>[lnd]i</code><br />
|-<br />
|31<br />
|{{w|Herbert Hoover|Herbert H<u>oo</u>ver}}<br />
|<code>[po]o</code><br />
|-<br />
|32<br />
|{{w|Franklin D. Roosevelt|Franklin D. R<u>oo</u>sevelt}}<br />
|<code>[po]o</code><br />
|-<br />
|33<br />
|{{w|Harry S. Truman|Harry S. Tru<u>ma</u>n}}<br />
|<code>[mtg]a</code><br />
|-<br />
|34<br />
|{{w|Dwight D. Eisenhower|Dwight D. Eise<u>nh</u>ower}}<br />
|<code>n[hl]</code><br />
|-<br />
|35<br />
|{{w|John F. Kennedy|John F. Kenn<u>ed</u>y}}<br />
|<code>[ae]d</code><br />
|-<br />
|36<br />
|{{w|Lyndon B. Johnson|Lyndon B. <u>J</u>ohnson}}<br />
|<code>j</code><br />
|-<br />
|37<br />
|{{w|Richard Nixon|Richard <u>Ni</u>xon}}<br />
|<code>[lnd]i</code><br />
|-<br />
|39<br />
|{{w|Jimmy Carter|Jimmy Ca<u>rt</u>er}}<br />
|<code>[rn]t</code><br />
|-<br />
|40<br />
|{{w|Ronald Reagan|Ronald Rea<u>ga</u>n}}<br />
|<code>[mtg]a</code><br />
|-<br />
|41<br />
|{{w|George H. W. Bush|George H. W. <u>Bu</u>sh}}<br />
|<code>bu</code><br />
|-<br />
|42<br />
|{{w|Bill Clinton|Bill Cli<u>nt</u>on}}<br />
|<code>[rn]t</code><br />
|-<br />
|43<br />
|{{w|George W. Bush|George W. <u>Bu</u>sh}}<br />
|<code>bu</code><br />
|-<br />
|44<br />
|{{w|Barack Obama|Barack Oba<u>ma</u>}}<br />
|<code>[mtg]a</code><br />
|}<br />
<br />
Note that some presidents are missing because they weren't elected but became presidents after the resignation/death of their formers.<br />
<br />
Note also that Randall's regular expression must be modified slightly, because it also matches {{w|John C. Fremont|John C. Fremo<u>nt</u>}}, the runner-up to James Buchanan in 1856, as discussed by {{w|Peter Norvig}} at [http://nbviewer.ipython.org/url/norvig.com/ipython/xkcd1313.ipynb xkcd 1313: Regex Golf]. Note that Norvig provides a small amount of Python code which actually plays regex golf with arbitrary lists, and found a shorter solution than Randall's for the ''Star Wars'' vs ''Star Trek'' game.<br />
<br />
==Transcript==<br />
:Regex golf:<br />
:[Megan is sitting at a laptop. Cueball is standing behind her.]<br />
:Megan: You try to match one group but not the other.<br />
:Megan: /m | [tn]|b/ matches ''Star Wars'' subtitles but not ''Star Trek''.<br />
:Cueball: Cool.<br />
<br />
:Meta-regex golf:<br />
:[A close-up of Megan at her laptop.]<br />
:Megan: So I wrote a program that plays regex golf with arbitrary lists...<br />
:Cueball (offscreen): Uh oh...<br />
<br />
:Meta-meta-regex golf:<br />
:[Megan typing at her laptop.]<br />
:Megan: ...But I lost my code, so I'm grepping for files that look like regex golf solvers.<br />
:[Cueball facepalming.]<br />
<br />
:...And beyond:<br />
:[Another closeup of Megan at her laptop.]<br />
:Megan: Really, this is all /(meta-)*regex golf/.<br />
:Cueball: Now you have ''infinite'' problems.<br />
:Megan: No, I had those already.<br />
<br />
==Trivia==<br />
*There are now at least four comics that references regular expressions. The other three are: [[208: Regular Expressions]], [[224: Lisp]] and [[1171: Perl Problems]].<br />
*Additionally, regular expressions are mentioned in title text of [[1277: Ayn Random]].<br />
*A regular expression is used in the [http://what-if.xkcd.com/75/ 75th] episode of [[what if?]] to calculate the answer that week's question.<br />
*Also, Randall mentions [http://regex.alf.nu/ a website with a regexp golf game] he got distracted by while researching for the [http://what-if.xkcd.com/78/ 78th] episode of [[what if?]] (which was published one day after this comic).<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Regex]]</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:1494:_Insurance&diff=88244Talk:1494: Insurance2015-04-03T13:33:31Z<p>173.245.54.190: Fire Insurance joke</p>
<hr />
<div>Well...suck for you.<br />
[[Special:Contributions/108.162.215.57|108.162.215.57]] 05:17, 4 March 2015 (UTC) RobotGoggles<br />
<br />
<br />
'''Incomplete tag?'''<br />
I know it's pretty early, and the explanation is bound to be rewritten, but the current explanation is a little confusing, and makes a couple jumps that I wouldn't necessarily make. Maybe the incomplete tag shouldn't be removed yet? I'd do it, but I don't really know enough about actually editing the explanations to feel comfortable doing it yet.<br />
[[User:ARoseByAnyOtherName|ARoseByAnyOtherName]] ([[User talk:ARoseByAnyOtherName|talk]]) 08:52, 4 March 2015 (UTC)<br />
<br />
: I mean, I had written an explanation I'd say was a bit clearer (if a bit more complicated), but some unregistered user removed most of it... Makes me a bit grumpy. The newly added ''Lifehacks vs. IT hacks'' section brings up most of the things that person removed, though, so this should be complete enough. [[User:Obskyr|Obskyr]] ([[User talk:Obskyr|talk]]) 09:44, 4 March 2015 (UTC)<br />
<br />
:: Well, for what it's worth, I liked your version better. --[[User:RenniePet|RenniePet]] ([[User talk:RenniePet|talk]]) 10:47, 4 March 2015 (UTC)<br />
:::Not only that. The new version was so bad I decided to revert to Obskyr's. [http://www.explainxkcd.com/wiki/index.php?title=1494%3A_Insurance&diff=85633&oldid=85624] [[Special:Contributions/108.162.221.201|108.162.221.201]] 13:54, 4 March 2015 (UTC)<br />
<br />
;Any meaning to conveyer?<br />
<br />
The spelling error in the alt text seems like a simple typo.<br />
<br />
Lawyer? I assumed it was a salesman or HR guy. --[[User:RenniePet|RenniePet]] ([[User talk:RenniePet|talk]]) 08:50, 4 March 2015 (UTC)<br />
:: Insurance agent. Not exactly a salesman; agents have multiple hats. You don't get fire insurance from HR.[[User:Taibhse|Taibhse]] ([[User talk:Taibhse|talk]]) 09:34, 4 March 2015 (UTC)<br />
:::So you're saying the agents are TF2 players. [[Special:Contributions/108.162.237.161|108.162.237.161]] 04:45, 6 March 2015 (UTC)<br />
<br />
This is probably a reference to those youtube videos of ''life hacks'' of questionable legality. Eg signing up for one flight to take another[[Special:Contributions/108.162.219.100|108.162.219.100]] 16:44, 4 March 2015 (UTC)<br />
<br />
I guess this might also relate to that (from my experience) programmers tend to like to break things (anything claimed to be "secure" seems to attract lots of people wanting to test out how secure) or find workarounds for things? [[User:Pinkishu|Pinkishu]] ([[User talk:Pinkishu|talk]]) 10:11, 4 March 2015 (UTC)<br />
<br />
;Hacking<br />
<br />
Please read [https://stallman.org/articles/on-hacking.html On Hacking]. I think the term you're looking for is cracking, or at least black hat hacking. Hacking a system would mean getting a system to do something unique and/or interesting. Or interacting with the system in a way that wasn't predicted. [[Special:Contributions/108.162.238.191|108.162.238.191]] 10:19, 4 March 2015 (UTC)<br />
:You're right. But there is at least a second common usage for the word hack that is described by wikipedia as "an inelegant but effective solution to a computing problem". When the insurance guy speaks about "cool hacks", he's probably not refering to Stallman's definition. [[User:Nytux|Nytux]] ([[User talk:Nytux|talk]]) 09:41, 5 March 2015 (UTC)<br />
<br />
;Hard hacks<br />
Things like lock-picking is often also seen as physical equivalents of hacking, not necessarily illegal but still something most people would look on with suspicion.[[Special:Contributions/108.162.254.98|108.162.254.98]] 10:21, 4 March 2015 (UTC)<br />
<br />
:Agree, this is excellent example on "hacking the computer": there is nothing illegal on lock-picking itself. Even if you use it on someone's else door without permission, it would not be crime unless you actually ENTER the door (or damage the lock). Locksmiths MUST know how to do it. But ... first thing you think about when hearing lock-picking is that thiefs do it. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 11:37, 4 March 2015 (UTC)<br />
::Before coming down into the comments, and seeing the last set of comments, I felt it necessary to make an edit to highlight just such an issue regarding the confusion about 'hacking'. As a historical sideline, note also the term "cracksman" as used for those who illegally open safes (and others skilled with locks and barred entranceways, in a criminal manner), which predates all the above computer-era terminology. But I didn't want to add ''too'' much more to the explanation. [[Special:Contributions/141.101.98.181|141.101.98.181]] 17:25, 4 March 2015 (UTC)<br />
<br />
I think part of the point of today's comic is to point that contracts are somewhat similar to a computer program (both have definitions and rules by which the system must abide), but lack the strict rigor of the latter. So, when programmers read a legal contract they immediately start searching for bugs or vulnerabilities or even syntax optimizations. {{unsigned ip|188.114.98.29}}<br />
<br />
;Why is it illegal to do things allowed by the contract?<br />
Why is it illegal if the insurance company agreed that the "fraudulent" maneuver was accepted, by signing the contract allowing it?<br />
[[Special:Contributions/199.27.128.172|199.27.128.172]] 23:22, 4 March 2015 (UTC)<br />
<br />
The contract doesn't have a section that says "and fraud is prohibited" because fraud is already prohibited by criminal law; thus, no need to spell it out. It turns out that contracts will have many terms added by implication, particularly commercial contracts.<br />
<br />
:If you buy a shiny new gun, the instruction manual probably doesn't say "Oh, and by the way, if you point this thing at someone and pull the trigger while it's loaded, you may be charged with a crime." You're supposed to know that this is true BEFORE you buy a gun. That's part of the joke... normal people know that looking for ways to get the insurance to pay out more than it should is insurance fraud. People who think like programmers think they've found a loophole they can exploit. {{unsigned ip|108.162.237.170}}<br />
<br />
::Still, it's fraud to deliberately lie to the insurance company to make more money. I still don't see how taking advantage of the insurance company's mistakes is fraud, especially when you're just following the contract. Do companies have special privileges and entitlements to profit? --[[Special:Contributions/199.27.128.172|199.27.128.172]] 01:09, 11 March 2015 (UTC)<br />
<br />
::Another problem with your analogy is that shooting someone with a gun is a crime against a person, not the gun seller, while fraud is a crime against the other party. --[[Special:Contributions/199.27.128.172|199.27.128.172]] 01:21, 11 March 2015 (UTC)<br />
<br />
; ...<br />
<br />
Uh, why doesn't it mention life hacks at all in the "lifehacks vs IT hacks" section? Especially since I remember some lifehacks actually advocate for plain fucking stealing, like e.g. one which suggested that if you need a free umbrella, go to a restaurant and say you lost a black umbrella. [[Special:Contributions/141.101.89.224|141.101.89.224]] 01:56, 5 March 2015 (UTC)<br />
:I absolutely agree with this point. The comic appears to suggest that programmers apply the conditioning that comes from their jobs (that code exploits are cool, and that the system must be designed to prevent exploits) to life (where exploiting a system's vulnerabilities may look cool but is very probably illegal). The airport luggage registration and screening system allows anyone to walk out the door with any item of luggage, but it is quite simply theft to do so. Likewise, exploiting a loophole in a contract is generally acceptable in order to avoid work or liability, but when you do it to obtain material gain then it is quite simply fraud. It would appear that much of the explanation currently misses the point... [[Special:Contributions/108.162.229.50|108.162.229.50]] 13:35, 5 March 2015 (UTC)<br />
<br />
;Checking the luggage<br />
<br />
Seems like someone already tried this.<br />
I flew to Saigon last week and they check your luggage against your lost&found tag, before you may leave.<br />
--[[Special:Contributions/108.162.222.156|108.162.222.156]] 15:54, 5 March 2015 (UTC)<br />
: Correct. Most airports don't check the luggage tags, but I've been to some that do. Don't remember which. May have been South Asia too. [[User:Chrisahn|Chrisahn]] ([[User talk:Chrisahn|talk]]) 14:20, 8 March 2015 (UTC)<br />
<br />
I disagree that this is a sequel to ''UV'', it may relate, but as mentioned in that comment it's not even close to legal to burn a house then get fire insurance. [[User:Djbrasier|Djbrasier]] ([[User talk:Djbrasier|talk]]) 19:24, 5 March 2015 (UTC)<br />
<br />
Also, isn't [[Hairy]] the insurance agent? Should the transcript be updated to name him? [[User:Djbrasier|Djbrasier]] ([[User talk:Djbrasier|talk]]) 19:29, 5 March 2015 (UTC)<br />
<br />
;reminds me of an old joke<br />
I'm surprised that no one here has mentioned this joke, so I'll tell it (I think I read it in Reader's Digest back in my childhood): A farmer has just signed a fire insurance contract and as he hands the first premium payment to the salesman asks, "So how much will I get if the barn were to burn down tonight?" to which the salesman replies, "Oh, probably 10 to 20." [[Special:Contributions/173.245.54.190|173.245.54.190]] 13:33, 3 April 2015 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:167:_Nihilism&diff=88064Talk:167: Nihilism2015-04-02T10:37:00Z<p>173.245.54.190: </p>
<hr />
<div>That's his logic for dong random stuff?[[User:Guru-45|Guru-45]] ([[User talk:Guru-45|talk]]) 16:33, 10 March 2013 (UTC)<br />
<br />
:He is saying that climbing a tree is as reasonable a response to nihilism as acting all mopey and depressed. [[Special:Contributions/184.66.160.91|184.66.160.91]] 03:21, 27 August 2013 (UTC)<br />
<br />
And he is soooo correct. I wish I knew now what a waste of time worrying about certain things happening or not happening would wind up being. I wish I'd spent more time climbing trees or doing other things that made me feel happy or that I had fun doing instead of worrying about how I would look to others doing so. Life should come with a users manual or at least a FAQ or something. I know, I know there's lots of books out there that attempt to do that but I mean one that you KNOW is true because it was written for YOU. [[Special:Contributions/173.245.54.190|173.245.54.190]] 10:37, 2 April 2015 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:162:_Angular_Momentum&diff=88059Talk:162: Angular Momentum2015-04-02T10:19:37Z<p>173.245.54.190: </p>
<hr />
<div>The issue date is not given, as i don't have a clue about it. Could someone fix this? [[User:Rikthoff|Rikthoff]] ([[User talk:Rikthoff|talk]]) 19:30, 3 August 2012 (EDT)<br />
<br />
:When the page was updated to the new comic template by [[User:Bpothier]] he fixed the date. [[User:Lcarsos|lcarsos]] ([[User talk:Lcarsos|talk]]) 20:48, 28 August 2012 (UTC)<br />
<br />
That actually is a neat physics puzzle, which has probably (i.e. certainly) been addressed somewhere on the net. I may incorporate that some day. --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 05:58, 24 August 2013 (UTC)<br />
<br />
I tried to calculate the change in Earth's period, assuming that she was standing in the north pole (latitude = 90º N), where her spinning would have more effect. I either did something wrong, or my TI-84 Plus is not capable of detecting the very small effect her spinning would have on the Earth's rotation. I assumed the Earth had a period of exactly 24 hours, and got the same value to the second, even if she was spinning at 1000 turns per second, which seems like a lot.<br />
<br />
Here's the formula:<br />
<br />
L_Earth_i = L_Earth_f + L_spinner <=><br />
<br />
I_Earth * (2*PI)/T_Earth_i = I_Earth * (2*PI)/T_Earth_f + I_spinner* (2*PI) * f_spinner <=><br />
<br />
(1/T_Earth_f) = (1/T_Earth_i) - (I_spinner/I_Earth)*f_spinner <=><br />
<br />
T_Earth_f = 1/((1/T_Earth_i) - (I_spinner/I_Earth)*f_spinner)<br />
<br />
<br />
Where the variables have names in the format:<br />
<br />
[variable name]_[object it refers to]_[situation (i or f stand for initial and final)]<br />
<br />
<br />
L = Angular Moment<br />
<br />
I = Moment of Inertia<br />
<br />
T = Period of rotation about one's axis<br />
<br />
f = frequency<br />
<br />
<br />
I used as values:<br />
<br />
T_Earth_i = 86400 seconds (24 hours exactly)<br />
<br />
I_spinner = 62,04 Kg.m^2 (Found on Wolfram|Alpha, for a 62Kg adult human being)<br />
<br />
I_Earth = 8,03e+37 Kg.m^2 (http://scienceworld.wolfram.com/physics/MomentofInertiaEarth.html)<br />
<br />
f_spinner = the frequency of the woman's spinning in complete turns per second. {{unsigned ip|2.82.142.28}}<br />
<br />
:Taking that a bit further, the relative decrease is:<br />
<br />
(T_Earth_f - T_Earth_i)/T_Earth_i = 1 / (I_Earth/(I_spinner*T_Earth_i*f_spinner) - 1)<br />
= 1 / ( 1.5 e+28 - 1) ~= 67 e-30<br />
<br />
:Fwiw, the absolute value is 5.767 yocto-seconds. If the ''entire'' world population would spin at that 1000 turns per second (and at favourable locations as in your assumptions), the effect will still be a measly 0.041 pico-seconds. So T_Earth_f = 86 399.999 999 999 999 958 ... But the TI-84 only has about 14 digits precision, i believe, so even that won't show up. -- [[Special:Contributions/173.245.51.210|173.245.51.210]] 22:46, 30 October 2013 (UTC)<br />
<br />
Is it possible for someone to write an equation that factors in latitude (and, if relevant, longitude) that we could plug our locations into and get a value from? That would be awesome. Thanks. [[Special:Contributions/108.162.250.208|108.162.250.208]] 02:48, 23 February 2014 (UTC)<br />
<br />
The visual style and theme of this comic is clearly referencing the 'Spinning Ballerina Optical Illusion' (evidenced by the grey-to-white gradient 'glow', as well as her arm and leg positions).<br />
[[Special:Contributions/108.162.249.231|108.162.249.231]] 03:03, 30 September 2014 (UTC)<br />
<br />
The 'Spinning Ballerina' optical illusion does not apply here, Megan clearly stated that she was spinning 'counterclockwise' and due to the fact that she is drawn with hair (not a silhouette) lets you know where she is facing. Therefore the bent leg on the right of the image is her left leg. Plus there aren't many ways to draw a stick figure 'spinning'. Now if it were Cueball doing the spinning THEN I would agree with you because there would not be a reference point to make any type of judgement and therefore a point could be made that could be a reference Randall was trying to make.<br />
[[User:Nexxuz|Nexxuz]] ([[User talk:Nexxuz|talk]])<br />
<br />
The momentum of Megan is in fact one order of magnitude smaller than what appeared in above calculation, so the dilation effect is still smaller.<br />
<br />
http://www.wolframalpha.com/input/?i=moment+of+inertia+of+solid+cylinder+for+a%3D0.25m%2Cmass%3D62kg {{unsigned ip|173.245.50.90}}<br />
<br />
After reading this comics, I got one question. I thought one cant change the total momentum of a closed system of bodies. I mean, from the point of view outside of Earth, she would be spinning, but the momentum which Megan, or whatever her name is, gained in counter-clock-wise direction would also show in Earth clock-wise direction (positively). Basically I am referring to a situation of a man walking on a boat. (the boat moves, the man moves, but the position man-lake is still the same). So I figured it should be in this way. She spins, yeah, but the Earth now spins in opposite direction a little more, so in the end it is still the same.<br />
Now, she could totally delay time by approaching light speed as she spins, which would be weird though as her head (closer to rotational axis) would have smaller velocity than her hands (and thus faster time flow) resulting in, hmm, her body parts getting lost in time? {{unsigned ip|141.101.97.220}}<br />
<br />
Wouldn't she have to be spinning at the Geographic North Pole to have any effect? As it is she's spinning with her axis of rotation at some angle (depending on latitude ) to the Earth's axis of rotation so she's not having much of any effect at all. [[Special:Contributions/173.245.54.190|173.245.54.190]] 10:15, 2 April 2015 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:162:_Angular_Momentum&diff=88056Talk:162: Angular Momentum2015-04-02T10:15:32Z<p>173.245.54.190: </p>
<hr />
<div>The issue date is not given, as i don't have a clue about it. Could someone fix this? [[User:Rikthoff|Rikthoff]] ([[User talk:Rikthoff|talk]]) 19:30, 3 August 2012 (EDT)<br />
<br />
:When the page was updated to the new comic template by [[User:Bpothier]] he fixed the date. [[User:Lcarsos|lcarsos]] ([[User talk:Lcarsos|talk]]) 20:48, 28 August 2012 (UTC)<br />
<br />
That actually is a neat physics puzzle, which has probably (i.e. certainly) been addressed somewhere on the net. I may incorporate that some day. --[[User:Quicksilver|Quicksilver]] ([[User talk:Quicksilver|talk]]) 05:58, 24 August 2013 (UTC)<br />
<br />
I tried to calculate the change in Earth's period, assuming that she was standing in the north pole (latitude = 90º N), where her spinning would have more effect. I either did something wrong, or my TI-84 Plus is not capable of detecting the very small effect her spinning would have on the Earth's rotation. I assumed the Earth had a period of exactly 24 hours, and got the same value to the second, even if she was spinning at 1000 turns per second, which seems like a lot.<br />
<br />
Here's the formula:<br />
<br />
L_Earth_i = L_Earth_f + L_spinner <=><br />
<br />
I_Earth * (2*PI)/T_Earth_i = I_Earth * (2*PI)/T_Earth_f + I_spinner* (2*PI) * f_spinner <=><br />
<br />
(1/T_Earth_f) = (1/T_Earth_i) - (I_spinner/I_Earth)*f_spinner <=><br />
<br />
T_Earth_f = 1/((1/T_Earth_i) - (I_spinner/I_Earth)*f_spinner)<br />
<br />
<br />
Where the variables have names in the format:<br />
<br />
[variable name]_[object it refers to]_[situation (i or f stand for initial and final)]<br />
<br />
<br />
L = Angular Moment<br />
<br />
I = Moment of Inertia<br />
<br />
T = Period of rotation about one's axis<br />
<br />
f = frequency<br />
<br />
<br />
I used as values:<br />
<br />
T_Earth_i = 86400 seconds (24 hours exactly)<br />
<br />
I_spinner = 62,04 Kg.m^2 (Found on Wolfram|Alpha, for a 62Kg adult human being)<br />
<br />
I_Earth = 8,03e+37 Kg.m^2 (http://scienceworld.wolfram.com/physics/MomentofInertiaEarth.html)<br />
<br />
f_spinner = the frequency of the woman's spinning in complete turns per second. {{unsigned ip|2.82.142.28}}<br />
<br />
:Taking that a bit further, the relative decrease is:<br />
<br />
(T_Earth_f - T_Earth_i)/T_Earth_i = 1 / (I_Earth/(I_spinner*T_Earth_i*f_spinner) - 1)<br />
= 1 / ( 1.5 e+28 - 1) ~= 67 e-30<br />
<br />
:Fwiw, the absolute value is 5.767 yocto-seconds. If the ''entire'' world population would spin at that 1000 turns per second (and at favourable locations as in your assumptions), the effect will still be a measly 0.041 pico-seconds. So T_Earth_f = 86 399.999 999 999 999 958 ... But the TI-84 only has about 14 digits precision, i believe, so even that won't show up. -- [[Special:Contributions/173.245.51.210|173.245.51.210]] 22:46, 30 October 2013 (UTC)<br />
<br />
Is it possible for someone to write an equation that factors in latitude (and, if relevant, longitude) that we could plug our locations into and get a value from? That would be awesome. Thanks. [[Special:Contributions/108.162.250.208|108.162.250.208]] 02:48, 23 February 2014 (UTC)<br />
<br />
The visual style and theme of this comic is clearly referencing the 'Spinning Ballerina Optical Illusion' (evidenced by the grey-to-white gradient 'glow', as well as her arm and leg positions).<br />
[[Special:Contributions/108.162.249.231|108.162.249.231]] 03:03, 30 September 2014 (UTC)<br />
<br />
The 'Spinning Ballerina' optical illusion does not apply here, Megan clearly stated that she was spinning 'counterclockwise' and due to the fact that she is drawn with hair (not a silhouette) lets you know where she is facing. Therefore the bent leg on the right of the image is her left leg. Plus there aren't many ways to draw a stick figure 'spinning'. Now if it were Cueball doing the spinning THEN I would agree with you because there would not be a reference point to make any type of judgement and therefore a point could be made that could be a reference Randall was trying to make.<br />
[[User:Nexxuz|Nexxuz]] ([[User talk:Nexxuz|talk]])<br />
<br />
The momentum of Megan is in fact one order of magnitude smaller than what appeared in above calculation, so the dilation effect is still smaller.<br />
<br />
http://www.wolframalpha.com/input/?i=moment+of+inertia+of+solid+cylinder+for+a%3D0.25m%2Cmass%3D62kg {{unsigned ip|173.245.50.90}}<br />
<br />
After reading this comics, I got one question. I thought one cant change the total momentum of a closed system of bodies. I mean, from the point of view outside of Earth, she would be spinning, but the momentum which Megan, or whatever her name is, gained in counter-clock-wise direction would also show in Earth clock-wise direction (positively). Basically I am referring to a situation of a man walking on a boat. (the boat moves, the man moves, but the position man-lake is still the same). So I figured it should be in this way. She spins, yeah, but the Earth now spins in opposite direction a little more, so in the end it is still the same.<br />
Now, she could totally delay time by approaching light speed as she spins, which would be weird though as her head (closer to rotational axis) would have smaller velocity than her hands (and thus faster time flow) resulting in, hmm, her body parts getting lost in time? {{unsigned ip|141.101.97.220}}<br />
<br />
Wouldn't she have to be spinning at the Geographic North Pole to have any effect? As it is she's spinning with her axis of rotation perpendicular to the center of mass (assumed to be the center of rotation) so she's not having any effect at all. [[Special:Contributions/173.245.54.190|173.245.54.190]] 10:15, 2 April 2015 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:161:_Accident&diff=88036Talk:161: Accident2015-04-02T04:32:37Z<p>173.245.54.190: </p>
<hr />
<div>The issue date of the comic is not given. Can someone add this? [[User:Rikthoff|Rikthoff]] ([[User talk:Rikthoff|talk]]) 18:53, 3 August 2012 (EDT)<br />
<br />
http://xkcd.com/851/ - more katamari damacy shenanigans {{unsigned ip|128.237.217.152}}<br />
<br />
In guitar hero you tilt the controler to active star power.<br />
If you did so with steering wheel you would crash. 21:47, 10 January 2014 (UTC) {{unsigned ip|173.245.52.205}}<br />
Any reason for an incomplete? [[Special:Contributions/199.27.128.144|199.27.128.144]] 06:29, 16 January 2014 (UTC)<br />
<br />
I have changed the last part about the title text, as it referred to playing the games while driving, rather than listening to the music. Although the idea is that you then think you are playing! I hope my wording makes more sense. I have never played either of the two games, and cannot say if the explanation for driving poorly while listening to guitar hero music makes sense. But if it does, I would say it was OK to remove the incomplete tag now! [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 13:45, 16 January 2014 (UTC)<br />
:I have never played guitar hero either, but I believe the game shows a series of objects approaching you to represent the notes. The point is then to "hit" large objects, much like the point of Katamari Damacy is to hit small objects. This makes more sense since otherwise any game music could simply distract you from driving.<br />
:Is there a guitar hero player reading this who could make a final edit?--[[Special:Contributions/108.162.242.8|108.162.242.8]] 00:45, 17 January 2014 (UTC)<br />
::I don't think guitar hero has to do with hitting things, as much as doing sudden turns and hitting your horn on certain notes..[[Special:Contributions/108.162.216.79|108.162.216.79]] 14:24, 19 May 2014 (UTC)<br />
<br />
After I play a lot of Mario Kart, I feel urges to run over boxes, and to shake the steering wheel on top of speed bumps. - [[Special:Contributions/173.245.54.90|173.245.54.90]] 15:06, 14 May 2014 (UTC)<br />
<br />
After playing a lot of Elder Scrolls, I find myself wanting to harvest all the flowers I see. How else am I going to become an expert alchemist? {{unsigned ip|108.162.216.96}}<br />
<br />
After playing an rpg for hours then going out into public, I find myself scanning windows, doors, vehicles. Staying close to the edges with my head on a swivel, eyes moving like turrets focusing on any one who gets within "range" and IFF them. Walk into a room and move to the corners scanning for targets. I can see the attraction to paintball and laser tag.04:32, 2 April 2015 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=150:_Grownups&diff=88008150: Grownups2015-04-01T23:26:57Z<p>173.245.54.190: /* Transcript */</p>
<hr />
<div>{{comic<br />
| number = 150<br />
| date = August 30, 2006<br />
| title = Grownups<br />
| image = Grownups.png<br />
| titletext = I've looked into this, and I can't figure out a way to do it cheaply. And I guess it wouldn't be sanitary.<br />
}}<br />
<br />
==Explanation==<br />
[[Randall]] is playing with the child/grownup setup again. During childhood, adults ("grownups") make most of the decisions and put constraints on what their children do. As children age and eventually become grownups, there are some things that they do not do anymore, as they see them as childish. <br />
<br />
[[Megan]] has taken these thoughts seriously, and realizes that with her newfound freedom as a grownup, she gets to define what her adulthood means. Free from constraints, she goes ahead and creates a {{w|ball pit|playpen}} in her apartment of colored plastic balls. [[Cueball]] admires this spirit and enters the playpen. It is difficult to decipher Randall's true intent behind this somewhat cryptic comic, but it seems from the heart that the two are making love in the balls.<br />
<br />
The title text reveals that [[Randall]] also would like to make his own playpen, but he finds it [http://playpenballs.com/index.php?route=product/category&path=60 expensive to buy] and also hard to [http://www.reddit.com/r/mildlyinteresting/comments/1q6bru/this_is_how_they_clean_the_plastic_balls_from_the/ keep clean]. Both of these are true - see links. Most public playpens can easily become very dirty as many children and toddlers play in them.<br />
<br />
This is one of the five comics linked at the bottom part of the xkcd.com website.<br />
<br />
==Transcript==<br />
:[Cueball is talking to Megan who is behind a waist-high screen across a doorway with colorful playpen balls behind her.]<br />
:Cueball: Hey, I was wondering if you had plans for-- holy crap, what happened to your apartment?<br />
:Megan: I filled it with playpen balls!<br />
:Cueball: I... what? Why?<br />
:Megan: Because we're grown-ups now, and it's our turn to decide what that means.<br />
:[Both vanish into the apartment, balls spilling out into the corridor. A love heart drifts out the door, indicating you-know-what.(I think the heart might mean they're loving the nostalgia and how it felt to be a kid playing in a ball pit.)]<br />
<br />
==Trivia==<br />
*[[Randall]], author of the comic, actually built one in his apartment, which he talks about and shows pictures of at [http://blog.xkcd.com/2007/11/19/growing-up/ here] and [http://blog.xkcd.com/2008/02/27/ballpit-phase-ii/ here]. Speaking of cost, [http://www.chiliahedron.com/ballroom/ chiliahedron.com] has a calculator for how much it would cost to make your own ball pit.<br />
<br />
*China takes the cake for this, though. China currently holds the record for the worlds largest ballpit: a [http://www.mymodernmet.com/profiles/blogs/china-worlds-largest-ball-pit swimming pool filled with 1 million balls].<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics with color]]<br />
[[Category:Romance]]<br />
[[Category:Sex]]<br />
[[Category:Playpen balls]]<br />
[[Category:Footer comics]]</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=482:_Height&diff=84489482: Height2015-02-14T04:43:28Z<p>173.245.54.190: /* Objects */</p>
<hr />
<div>{{comic<br />
| number = 482<br />
| date = September 29, 2008<br />
| title = Height<br />
| before = [[#Explanation|↓ Skip to explanation ↓]]<br />
| image = height.png<br />
| titletext = Interestingly, on a true vertical log plot, I think the Eiffel Tower's sides would really be straight lines.<br />
}}<br />
<br />
==Explanation==<br />
The comic is a companion piece to [[485: Depth]]. Where ''Depth'' uses a {{w|logarithmic scale}} to depict the Earth at progressively greater magnification, from Earth's surface to the interior of a single proton, ''Height'' uses a logarithmic scale to depict the contents of the universe at progressively smaller distances, from the edge of the observable universe to the grass beneath our feet.<br />
<br />
Starting from the top, as one often does when reading comics, we begin with the top of the observable universe, described as being 46 billion {{w|light years}} out from the Earth. This is the longest distance that a ray of light has ever traveled to reach Earth. To the right of the text, [[Black Hat]] stands atop the comic, having just dropped a cat off the edge; he may be testing if cats always land on their feet, or may just be being a jerk, per his usual character. As one scrolls down, the depicted distances become less compressed, until arriving at the surface of Earth, all the while approaching a 1:1 scale with real-life distances. As shown in [[1162: Log Scale]], if Randall didn't do this, the comic would be much, MUCH longer.<br />
<br />
In this comic, most objects that are grounded on Earth are scaled logarithmically on the vertical axes and linearly on the horizontal axes (some are scaled linearly on both axes). Displaying objects in this manner noticeably distorts their shape; the Great Pyramid, for instance, looks not like a pyramid but like a bullet. In the title text, Randall muses on how the inwardly-curved sides of the Eiffel Tower might actually become perfectly straightened when subjected to this logarithmic distortion (although it is shown to bulge in the comic proper, meaning Randall probably doesn't fully believe his own musings).<br />
<br />
Outside of the Earth's atmosphere, the objects are placed at their actual distances from Earth on the log scale, but their shapes are not subjected to the logarithmic scaling of Earth objects, instead appearing as they would be seen (otherwise, round objects like the sun would appear more egg shaped, with the flatter side facing upward). However, objects are still much larger or much smaller than they would be in real life, in order to allow them to be properly seen.<br />
<br />
===Objects===<br />
All objects are sorted from bottom to top by their maximum distance from earth for objects in a solar orbit, and their current distance for others.<br />
<br />
{| class="wikitable"<br />
|-<br />
! Distance<br />
! Object<br />
! Description<br />
|-<br />
| 435&nbsp;×10<sup>24</sup>m<br />
| Black Hat and cat<br />
| Black Hat kicking a cat off the top of the comic, presumably to determine whether it will land on its feet.<br />
|-<br />
| 435&nbsp;×10<sup>24</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | Top of observable universe<br />
|-<br />
| 11.3&nbsp;×10<sup>24</sup>m<br />
| {{w|Hubble Deep Field}} objects<br />
| Objects of extremely distant galaxies found in a long-exposure photograph by of the Hubble telescope, 12 billion light-years away. The right most object is probably intended to be a pulsar, schematically shown from the side.<br />
|-<br />
| 9.46&nbsp;×10<sup>24</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | One billion light years<br />
|-<br />
| 3.1&nbsp;×10<sup>24</sup>m<br />
| {{w|Pulsar}}<br />
| A highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation.<br />
|-<br />
| 2.36&nbsp;×10<sup>24</sup>m<br />
| {{w|Great Attractor}}<br />
| An unusual concentration of intergalactic mass.<br />
|-<br />
| 425&nbsp;×10<sup>21</sup>m<br />
| {{w|Antennae Galaxies}} (colliding)<br />
| A pair of colliding galaxies.<br />
|-<br />
| 23.6&nbsp;×10<sup>21</sup>m<br />
| {{w|Andromeda Galaxy}}<br />
| A sibling to our Milky Way. It is the nearest spiral galaxy to ours.<br />
|-<br />
| 9.46&nbsp;×10<sup>21</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | One million light years<br />
|-<br />
| 2.38&nbsp;×10<sup>21</sup>m<br />
| [http://knowyourmeme.com/memes/cat-on-a-keyboard-in-space Cat on a keyboard in space]<br />
| An internet meme featuring a picture of a cat sitting on a musical keyboard, superimposed on an image of space.<br />
|-<br />
| 1.56&nbsp;×10<sup>21</sup>m<br />
| {{w|Magellanic Clouds}}<br />
| These clouds are a pair of nearby dwarf galaxies.<br />
|-<br />
| 263&nbsp;×10<sup>18</sup>m<br />
| Edge of Galaxy<br />
| The edge of the {{w|Milky Way}} galaxy, the galaxy in which we reside.<br />
|-<br />
| 245&nbsp;×10<sup>18</sup>m<br />
| {{w|Galactic Center}}<br />
| The center of the Milky Way galaxy.<br />
|-<br />
| 61.5&nbsp;×10<sup>18</sup>m<br />
| {{w|Crab Nebula}}<br />
| Nebula are supernova remnants<br />
|-<br />
| 14.2&nbsp;×10<sup>18</sup>m<br />
| {{w|Horsehead Nebula}}<br />
| A dark nebula that is part of the Orion Constellation.<br />
|-<br />
| 12.7&nbsp;×10<sup>18</sup>m<br />
| {{w|Orion Nebula}}<br />
| A nebula that is part of the Orion Constellation, just south of Orion's Belt.<br />
|-<br />
| 8.14&nbsp;×10<sup>18</sup>m<br />
| {{w|Rigel}}<br />
| The brightest star in the Orion Constellation it is actually a triple star system known alternatively as Beta Orionis<br />
|-<br />
| 6.08&nbsp;×10<sup>18</sup>m<br />
| {{w|Betelgeuse}}<br />
| The star Betelgeuse is displayed along with the location of {{w|Ford_Prefect (character)|Ford Prefect}} on his home planet which orbits Betelgeuse. Ford Prefect is a fictional character from the science fiction parody {{w|The Hitchhiker's Guide to the Galaxy}}.<br />
|-<br />
| 4.20&nbsp;×10<sup>18</sup>m<br />
| {{w|Pleiades}}<br />
| The Pleiades also have a derogatory remark, as per [[66: Abusive Astronomy]]<br />
|-<br />
| 2.90&nbsp;×10<sup>18</sup>m<br />
| The [http://en.memory-alpha.org/wiki/Romulan_Neutral_Zone Romulan Neutral Zone]<br />
| This marks the edge of the {{w|Star Trek}} Federation.<br />
|-<br />
| 931&nbsp;×10<sup>15</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | The first radio broadcast was in January 1910. Since radio waves travel at the speed of light, and this was published in September of 2008 this the radio waves traveled about 98.5 light years. See {{w|Contact (1997 film)}} for a depiction of this. This is also referenced in [[1212: Interstellar Memes]].<br />
|-<br />
| 350&nbsp;×10<sup>15</sup>m<br />
| {{w|Arcturus}}<br />
| An orange giant star that is part of the Boötes constellation.<br />
|-<br />
| 320&nbsp;×10<sup>15</sup>m<br />
| {{w|Pollux}}<br />
| One of the most distinct stars in the Gemini Constellation it is large Orange Giant with an apparent visual magnitude of 1.1<br />
|-<br />
| 242&nbsp;×10<sup>15</sup>m<br />
| The edge of {{w|Federation Sector 0-0-1}}<br />
| The sector of space assigned to Earth in {{w|Star Trek}}.<br />
|-<br />
| 224&nbsp;×10<sup>15</sup>m<br />
| {{w|Iraq and weapons of mass destruction|"missing WMDs"}}<br />
| A reference to the alleged weapons of mass destruction that were used as a pretence to mobilize the world population against Iraq, and start the Iraq war.<br />
|-<br />
| 81.3&nbsp;×10<sup>15</sup>m<br />
| {{w|Sirius}}<br />
|Also known as Alpha Canis Majoris, the Dog Star, or the North Star it is actually a binary system of Stars consisting of a main sequence white star and a small white dwarf.<br />
|-<br />
| 56.6&nbsp;×10<sup>15</sup>m<br />
| {{w|Barnard's Star}}<br />
| Barnards star is a very small red giant that is of great interest to astronomers as an achievement in the SIM (Space Interforometry Mission) to find a celestial object out of solar system that is a s small as 3 earth masses<br />
|-<br />
| 41.3&nbsp;×10<sup>15</sup>m<br />
| {{w|Alpha Centauri}}<br />
| Alpha Centauri is the closest star system to our planet.<br />
|-<br />
| 30.9&nbsp;×10<sup>15</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | One parsec.<br />
|-<br />
| 9.46&nbsp;×10<sup>15</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | One light-year.<br />
|-<br />
| 15.0&nbsp;×10<sup>15</sup>m<br />
| {{w|Oort cloud}}<br />
| A halo of ice balls surrounding our solar system, but missing the {{w|Kupier belt}} between Neptune and the Oort cloud.<br />
|-<br />
| 350&nbsp;×10<sup>12</sup>m<br />
| {{w|Bupkis}}<br />
| Yiddish for "nothing". Only a handful of objects are known to orbit between the Kuiper Belt and the Oort Cloud.<br />
|-<br />
| 55.0&nbsp;×10<sup>12</sup>m<br />
| A comet which will destroy earth in late 2063 <br />
| To coincide with the latest biblicaly based prophesy for the [http://www.askelm.com/prophecy/p971105.htm end of the world].<br />
|-<br />
| 19.5&nbsp;×10<sup>12</sup>m<br />
| {{w|Voyager 1}}<br />
| An early space probe. Distance correct as of 20th Nov 2014, click [http://voyager.jpl.nasa.gov/where/ here] to see NASA's live distance counter.<br />
|-<br />
| 16.7&nbsp;×10<sup>12</sup>m<br />
| {{w|Pioneer 10}}<br />
| Listed distance is an estimate based on {{w|Pioneer_10#Current_status|this information}}.<br />
|-<br />
| 17.7&nbsp;×10<sup>12</sup>m<br />
| {{w|Pioneer 11}}<br />
| By the similarity in appearance to Pioneer 10 this unlabeled probe must be Pioneer 11. Listed distance is an estimate based on {{w|Pioneer_11#Current_status|this information}}.<br />
|-<br />
| 14.5&nbsp;×10<sup>12</sup>m<br />
| {{w|Eris (dwarf planet)|Eris}}<br />
| One of a pair of {{w|Trans-Neptunian object}}s now classified as {{w|dwarf planet}}s. The "All hail Discordia!" after Eris is a reference to {{w|Discordianism}}, a somewhat tongue-in-cheek religion based around the goddess Eris. The distance is the maximum distance from earth.<br />
|-<br />
| 7.50&nbsp;×10<sup>12</sup>m<br />
| {{w|Pluto}}<br />
| One of a pair of {{w|Trans-Neptunian object}}s now classified as {{w|dwarf planet}}s. Pluto was originally classified as the 9th planet of the Solar system. Many people was appalled when it was suddenly degraded to dwarf planet. Obviously Randall does not think much of these people thus the comment: ''Not a planet. Neener neener''. The distance is the maximum distance of Pluto from Earth.<br />
|-<br />
| 4.70&nbsp;×10<sup>12</sup>m<br />
| {{w|Neptune}} <br />
| Neptune is displayed here with its moons. Neptune is the eighth and final planet in our solar system.<br />
|-<br />
| 3.20&nbsp;×10<sup>12</sup>m<br />
| {{w|Uranus}} <br />
| Uranus is dispayed here with its moons. Uranus is the seventh planet in our solar system.<br />
|-<br />
| 1.67&nbsp;×10<sup>12</sup>m<br />
| {{w|Saturn}} <br />
| Saturn is displayed along with its moons. One of Saturn's moons, most likely Titan, is labeled as a potential location to find life. Titan is the only known moon to have an atmosphere and oceans. The oceans cannot be filled with liquid water, as it is far too cold, but are instead filled with liquid methane and ethane. Some hypothisize that life could have formed in such oceans.<br />
|-<br />
| 928&nbsp;×10<sup>9</sup>m<br />
| {{w|Jupiter}} <br />
| Jupiter is displayed along with its moons. One of Jupiter's moons, most likely Europa, is labeled as a potential location to find life. Europa may be covered by a deep ocean of water found under a layer of ice many kilometers thick. Some hypothisize that life could have formed in such oceans.<br />
|-<br />
| 222&nbsp;×10<sup>9</sup>m<br />
| Asteroids<br />
| The {{w|Asteroid|Asteroid belt}} contains a spaceship from {{w|Asteroids (video game)}}<br />
|-<br />
| 133&nbsp;×10<sup>9</sup>m<br />
| {{w|Mars}}<br />
| Note the path, reflecting the fact that their distances from Earth vary as the planets move in their orbits with a maximum distance of 261 million km and a minimum of 54.6 million km.<br />
|-<br />
| 114&nbsp;×10<sup>9</sup>m<br />
| {{w|Venus}}<br />
| Note the path, reflecting the fact that their distances from Earth vary as the planets move in their orbits with a maximum distance of 401 million km and a minimum of 37.7 million km.<br />
|-<br />
| 138&nbsp;×10<sup>9</sup>m<br />
| {{w|Mercury}}<br />
| Mercury is the first planet in out solar system. The distance shown is the maximum distance from Earth.<br />
|-<br />
| 149&nbsp;×10<sup>9</sup>m<br />
| {{w|Sun}}<br />
| The Sun is the star at the center of our solar system, around which the Earth orbits.<br />
|-<br />
| 16.3&nbsp;×10<sup>9</sup>m<br />
| {{w|Discovery One}}<br />
| The Discovery One from {{w|2001: A Space Odyssey}}, referring to the quote "open the pod bay door, HAL." Also may be a reference to [[375: Pod Bay Doors]].<br />
|-<br />
| 9.43&nbsp;×10<sup>9</sup>m<br />
| Planet Express<br />
| The spaceplane is most likely the Planet Express from {{w|Futurama}}, where Fry once discussed "a big heaping bowl of salt." <br />
|-<br />
| 400&nbsp;×10<sup>6</sup>m<br />
| Human Altitude Record <br />
| Achieved by the team of {{w|Apollo 13}} approximately 100km higher than the remaining Apollo missions.<br />
|-<br />
| 384&nbsp;×10<sup>6</sup>m<br />
| {{w|Moon}} <br />
| The Moon is the Earth's only natural satellite.<br />
|-<br />
| 90.4&nbsp;×10<sup>6</sup>m<br />
| {{w|Snoop Dogg}}<br />
| A tongue-in-cheek reference to a rapper notorious for smoking marijuana, shown as having the second-highest altitude record. Someone who is taking drugs is said to be getting high.<br />
|-<br />
| 60.5&nbsp;×10<sup>6</sup>m<br />
| {{w|Space elevator}}<br />
| A proposed method of transporting cargo or people into orbit, consisting of a large mass beyond geosynchronous orbit, a station at the geosynchronous point, a cable connecting it to the Earth, and a climber that can scale the cable. Space elevators are also seen in [[697: Tensile vs. Shear Strength]] and [[536: Space Elevators]].<br />
|-<br />
| 42.1&nbsp;×10<sup>6</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | {{w|Geosynchronous orbit|Geosynchronous Orbit}}<br />
|-<br />
| 20.2&nbsp;×10<sup>6</sup>m<br />
| {{w|GPS (satellite)|GPS Satellites}}<br />
| GPS satellites are used for global positioning.<br />
|-<br />
| 3.94&nbsp;×10<sup>6</sup>m<br />
| {{w|Lunar Lander}} <br />
| The quote is a reference to {{w|Contact (1997 film)}} where the main character Ellie Arroway after witnessing a celestial light show up close says "Poetry! They should've sent a poet.".<br />
|-<br />
| 800&nbsp;×10<sup>3</sup>m<br />
| {{w|Space debris|Space Junk}}<br />
| There is a large quantity of defunct objects in orbit around the earth. Amongst other things, this includes old satellites, rocket stages and fragments from collisions or disintegration. Space junk is also referenced in [[1242: Scary Names]] under the title {{w|Kessler syndrome}}<br />
|-<br />
| 422.5&nbsp;×10<sup>3</sup>m<br />
| {{w|International Space Station}}<br />
| The ISS (International Space Station) is a multinational effort to put a research vessel in space. It is currently the largest artifical object in Earth's orbit, as well as the location of the longest continuous human presence in space.<br />
|-<br />
| 100&nbsp;×10<sup>3</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | The {{w|Edge of space|official edge of space}} as defined by the {{w|Kármán line}}<br />
|-<br />
| 76.0&nbsp;×10<sup>3</sup>m<br />
| {{w|Meteors}}<br />
| Meteors are chunks of rock (usually asteroids) that burn up in the atmosphere, producing the bright light associated with them. If the are large enough to hit the ground, they become meterorites, which is why Munroe labeled them only in the upper atmosphere.<br />
|-<br />
| 25.0&nbsp;×10<sup>3</sup>m<br />
| {{w|High-altitude balloon|High-altitude balloons}}<br />
| Unmanned balloons, typically filled with helium or hydrogen. The current altitude record was set in 2002 by a balloon named BU60-1 which reached 53,000m.<br />
|-<br />
| 16.1&nbsp;×10<sup>3</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 1/10 ATM = 0.1 {{w|Atmospheric pressure|atmosphere of pressure}}<br />
|-<br />
| 12.0&nbsp;×10<sup>3</sup>m<br />
| {{w|Airliner|Airliners}}<br />
| This is a typical cruising altitude of jet aircraft, equating to roughly 40,000 feet. (Aircraft altitude tends to be specified in feet rather than metres (yay!) ) <br />
|-<br />
| 8.84&nbsp;×10<sup>3</sup>m<br />
| {{w|Mount Everest}} <br />
| The Earths highest mountain, located in the {{w|Himalayas|Himalayan mountain range}} in South Asia.<br />
|-<br />
| 8.00&nbsp;×10<sup>3</sup>m<br />
| {{w|Cory Doctorow}} <br />
| Cory Doctorow in a balloon, a reference to comic [[239: Blagofaire]].<br />
|-<br />
| 6.34&nbsp;×10<sup>3</sup>m<br />
| {{w|Space Shuttle Columbia disaster}} <br />
| The {{w|Space Shuttle Columbia}} and its seven crew were lost when it disintegrated at [http://books.google.co.uk/books?id=6v16AgAAQBAJ&lpg=PA7&ots=LDKQ3nsNHs&dq=shuttle%20columbia%20altitude&pg=PA7#v=onepage&q=shuttle%20columbia%20altitude&f=false approximately 63,400m] in 2003. This number is inconsistent with the height of the graph by a factor of 10 probably a mistype by Randall.<br />
|-<br />
| 6.00&nbsp;×10<sup>3</sup>m<br />
| {{w|Helicopter}} <br />
| Though the record for helicopter altitude (without payload) is 12,442m, normal flying is usually performed much lower. In the US, 6000m is into {{w|Class A airspace}}, which is restricted and requires flight under {{w|Instrument Flight Rules}}.<br />
|-<br />
| 6.00&nbsp;×10<sup>3</sup>m<br />
| {{w|Cloud}} <br />
| Though not actually labelled there are a couple of clouds shown. While different cloud types vary in height, 6000m is roughly in the middle of the height range for clouds in temperate regions [http://weatherfaqs.org.uk/node/21]<br />
|-<br />
| 5.49&nbsp;×10<sup>3</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 1/2 ATM = 0.5 {{w|Atmospheric pressure|atmosphere of pressure}}<br />
|-<br />
| 1.78&nbsp;×10<sup>3</sup>m<br />
| [[Cueball]] <br />
| Apparently still using Python as shown in comic [[353: Python]].<br />
|-<br />
| 800&nbsp;×10<sup>0</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 800 meters<br />
|-<br />
| 800&nbsp;×10<sup>0</sup>m<br />
| {{w|Burj Khalifa|Burj Dubai}} <br />
| Now known as the Burj Khalifa, is the tallest building in the world.<br />
|-<br />
| 500&nbsp;×10<sup>0</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 500 meters<br />
|-<br />
| 400&nbsp;×10<sup>0</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 400 meters<br />
|-<br />
| 325&nbsp;×10<sup>0</sup>m<br />
| {{w|Eiffel Tower}} <br />
| A famous landmark in Paris, France.<br />
|-<br />
| 300&nbsp;×10<sup>0</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 300 meters<br />
|-<br />
| 200&nbsp;×10<sup>0</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 200 meters<br />
|-<br />
| 150&nbsp;×10<sup>0</sup>m<br />
| Kite <br />
| Kite string is commonly sold in large spools; a nice thick spool will probably hold 150 meters.<br />
|-<br />
| 140&nbsp;×10<sup>0</sup>m<br />
| {{w|Great Pyramid of Giza}} <br />
| One of the Seven Wonders of the Ancient World. It is located in Egypt.<br />
|-<br />
| 120&nbsp;×10<sup>0</sup>m<br />
| {{w|Baseball|Pop Fly}} <br />
| In Baseball a 'Pop Fly' is when the batter mis-hits the baseball, which then follows a tall arc deep into the infield where it's easy picking for the other team to catch on its way down. The highest recorded pop fly, not including those that landed in foul territory, was 172 meters.<br />
|-<br />
| 115&nbsp;×10<sup>0</sup>m<br />
| {{w|Redwood Tree|Redwood trees}} <br />
| The tallest trees in the world. At 115.61m (379.3ft) {{w|Hyperion (tree)|Hyperion}}, a Coast Redwood, holds the record for the tallest tree in the world.<br />
|-<br />
| 100&nbsp;×10<sup>0</sup>m<br />
| colspan="2" align="center" style="background: #ffdead;" | 100 meters<br />
|-<br />
| 20.0&nbsp;×10<sup>0</sup>m<br />
| {{w|Oak}} <br />
| While oaks may grow to be in excess of 40m in height, heights of around 20m are more typical. The person in the tree saying, "Hey, squirrels!" is a reference to [[167: Nihilism]].<br />
|-<br />
| 16.4&nbsp;×10<sup>0</sup>m<br />
| Tallest stilts <br />
| The tallest {{w|stilts}} recorded by the Guinness Book of World Records (as of November 2006) were 16.4 meters, or nearly 54 feet.<br />
|-<br />
| 13.0&nbsp;×10<sup>0</sup>m<br />
| {{w|Brachiosaurus|Brachiosaur}}<br />
| A large genus of dinosaur.<br />
|-<br />
| 8.00&nbsp;×10<sup>0</sup>m<br />
| {{w|Giraffe}} <br />
| The the tallest living terrestrial animal, with fully grown adults reaching in excess of 5m. While labelled 8m in the comic, the [http://www.big-animals.com/the-giraffe-the-worlds-tallest-animal/ record] for height is reported at 5.8m.<br />
|-<br />
| 1.70&nbsp;×10<sup>0</sup>m<br />
| {{w|Human height|Folks}}<br />
| Determining an average height of the world population is fraught with complications, but as a ballpark figure 1.7m is fairly accurate.<br />
|}<br />
<br />
==Transcript==<br />
:'''Top of observable universe'''<br />
:[Black Hat is standing on top, throwing a black kitty down.]<br />
:Black Cat: Mrowl!<br />
:[Map of the universe from observable universe to Earth. Each area of item is labeled. Labels left to right, up to down:]<br />
:(46 billion light years up)<br />
::Hubble Deep Field Objects<br />
:-One billion light years-<br />
::Great Attractor<br />
::Antennae Galaxies (colliding)<br />
::Andromeda<br />
::Holy crap lots of space<br />
:-One million light years-<br />
::Magellanic Clouds<br />
::Edge of galaxy<br />
::Galactic center<br />
::Crab Nebula<br />
::Orion Nebula<br />
::Horsehead Nebula<br />
::Romulan neutral zone<br />
::The Pleiades, duh!<br />
::Rigel<br />
::Betelgeuse<br />
::Ford Prefect<br />
:[Three arrows are pointing up above three lines with the following label:]<br />
:-Expanding shell of radio transmissions-<br />
::[Above a dotted line:]<br />
::Edge of federation sector 0-0-1<br />
::Pollux<br />
::Arcturus<br />
::Missing WMDs<br />
::Sirius<br />
::Barnard's Star<br />
::Alpha Centauri<br />
:-One parsec-<br />
:-One light year-<br />
::Oort Cloud (?)<br />
::Bupkis<br />
::Comet which will destroy Earth in late 2063<br />
::Pioneer 10<br />
::Voyager I<br />
::Eris (All hail Discordia!)<br />
::Pluto (Not a planet. Neener neener.)<br />
::Neptune<br />
::Uranus<br />
::Saturn<br />
::[Two arrows point to two moons, one next to each of the planets aboe and below.]<br />
::<-- Life --><br />
::Jupiter<br />
::Asteroids<br />
::Mars<br />
::Venus<br />
::Sun<br />
::Mercury<br />
::Spaceship Planet Express: Hey, a heaping bowl of salt!<br />
::Spaceship Discovery One: Open the fridge door, Hal.<br />
::Moon<br />
::Human altitude record (Apollo 13)<br />
::2nd place: Snoop Dogg<br />
::Space elevator - One of these days, promise!<br />
::Geosynchronous Orbit<br />
::GPS satellites<br />
::Lunar lander: In retrospect, they <u>shouldn't</u> have sent a poet. I have no idea how to land.<br />
::International Space Station<br />
::Space junk<br />
:-Official edge of space (100 km)-<br />
::Meteors<br />
:-1/10 ATM-<br />
::High altitude balloons<br />
::Airliners<br />
::Shuttle Columbia lost<br />
:-1/2 ATM-<br />
::Cory Doctrow<br />
::Everest<br />
::Helicopters (6000 m)<br />
::Cueball: Woo Python!<br />
::[A vertical scale is drawn along the right side of the picture, starting at 1 km and getting progressivly smaller and smaller.]<br />
:1 km<br />
:-800 m-<br />
::Burj Dubai (~800 m)<br />
:500<br />
:400<br />
::Eiffel Tower (325 m)<br />
:200<br />
::Kites<br />
::Great Pyramid (140 m)<br />
::Pop fly<br />
::Redwood (115 m)<br />
:100m<br />
::Oak (20 m)<br />
::A person in the oak: Hey squirrels!<br />
::Tallest stilts<br />
::Brachiosaur (13 m)<br />
::Giraffe (8 m)<br />
::[Megan and Cueball holding the kite are labeled:] <br />
::Folks<br />
:'''The observable universe, from top to bottom''''<br />
::~On a log scale~<br />
::Sizes are not to scale, but heights above the Earth's surface are accurate on a log scale (that is, each step up is double the height.)<br />
<br />
{{comic discussion}}<br />
[[Category:Charts]]<br />
[[Category:Large drawings]]<br />
[[Category:Comics featuring Cory Doctorow]]<br />
[[Category:Comics featuring Black Hat]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:278:_Black_Hat_Support&diff=74488Talk:278: Black Hat Support2014-08-28T18:18:25Z<p>173.245.54.190: </p>
<hr />
<div>select() calls are used to poll sockets for activity (read, write and exceptions), and I suspect the issue was that the timeout value (which is specified as part of select()'s parameters) was set too high judging from the overall content; Web servers and clients alike would suffer considerable latency as a result of waiting too long for I/O ports to activate. Thus it's likely the Apache install was misconfigured somehow, since the default settings should be sufficient for most purposes (in my limited experience since I work solely with nginx these days).<br />
<br />
I had this problem writing a server in PHP, and it took a while to get PHP (under Win32) to stop hogging my precious CPU cycles by successful application of nonblocking sockets and a short timeout parameter. [[User:Thokling|Thokling]] ([[User talk:Thokling|talk]]) 15:24, 20 September 2013 (UTC)<br />
<br />
:You are correct and I have modified the explanation. It could also be due to a loop polling a socket that will never be freed(a deadlock), this was my interpretation. [[Special:Contributions/108.162.246.117|108.162.246.117]] 07:05, 1 November 2013 (UTC)<br />
<br />
The explanations above don't seem to match "the load climbing out of control". The load typically means the CPU load, not latency. If the server is stuck on reading from a socket, the latency will grow but the load will plunge, since it's _waiting_ and thus not consuming the CPU cycles. Two typical problems connected with select() are: (1) As the number of sockets polled grows, the overhead of select() grows, so it uses more and more CPU just to go through all the sockets and check them all for readiness. (2) If some socket reports readiness through select() and then the program does not handle that readiness but keeps including this socket into the following select() calls, it will be stuck in a tight loop retrying select() and using all the available CPU of one processor. A less extreme variety of this case is the program being notified of multiple sockets being ready but handling only one socket before repeating select(). In this case the program will continue making progress but with the increased overhead of the unnecessary select() calls. [[Special:Contributions/108.162.246.5|108.162.246.5]] 21:07, 30 January 2014 (UTC)<br />
<br />
The start of the explanation refers to "black hat hackers" which doesn't seem relevant to the comic. I would have guessed that it relates to Red Hat, the company that sells and supports an enterprise Linux distribution (but becomes "Black Hat" because it is drawn in black and white). {{unsigned ip|108.162.208.155}}<br />
<br />
What about the sideways reference to "hang" in the title-text? Shouldn't _something_ be said about that in the explanation? [[Special:Contributions/173.245.54.190|173.245.54.190]] 18:18, 28 August 2014 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:1410:_California&diff=74021Talk:1410: California2014-08-20T12:54:55Z<p>173.245.54.190: Added a comment.</p>
<hr />
<div>''and remark that "They've gone plaid!"''<br />
I heard them say: <br />
"They've gone Plait!"<br />
I think it was "They've gone to plaid!" [[User:Chrullrich|Chrullrich]] ([[User talk:Chrullrich|talk]]) 08:16, 20 August 2014 (UTC)<br />
:Correct, the [http://sfy.ru/?script=spaceballs script] contains: They've gone to plaid. [[User:Condor70|Condor70]] ([[User talk:Condor70|talk]]) 08:36, 20 August 2014 (UTC)<br />
<br />
Spaceballs was parodying the use of surreal colours and patterns and the like when travelling at high speeds (ludicrous speed in the movie, hence its use in the legend of the graph) in older science fiction movies like 2001 a space odyssey. Plaid refers to the common textile pattern see:http://en.wikipedia.org/wiki/Plaid_(pattern). Also see: https://www.youtube.com/watch?v=ygE01sOhzz0. [[Special:Contributions/141.101.99.186|141.101.99.186]] 09:30, 20 August 2014 (UTC)<br />
:Spaceballs is really full of movie references! I originally saw the movie on BBC1, so I was surprised to see the Alien reference in the restaurant when I bought the DVD, because the BBC decided to cut the sequence for being distasteful! [[User:Condor70|Condor70]] ([[User talk:Condor70|talk]]) 11:36, 20 August 2014 (UTC)<br />
<br />
And here we have evidence of global warming. [[Special:Contributions/173.245.54.190|173.245.54.190]] 12:54, 20 August 2014 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=Talk:823:_Guest_Week:_David_Troupes_(Buttercup_Festival)&diff=73684Talk:823: Guest Week: David Troupes (Buttercup Festival)2014-08-14T16:20:49Z<p>173.245.54.190: Added a comment.</p>
<hr />
<div>Could the 'Woman' be Megan? [[Special:Contributions/173.245.54.190|173.245.54.190]] 16:20, 14 August 2014 (UTC)</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=734:_Outbreak&diff=73683734: Outbreak2014-08-14T16:19:07Z<p>173.245.54.190: /* Transcript */ Changed 'Cueball and Megan' to 'Ryan and Laura'.</p>
<hr />
<div>{{comic<br />
| number = 734<br />
| date = April 30, 2010<br />
| title = Outbreak<br />
| image = outbreak.png<br />
| titletext = Let's get dinner after we promptly destroy all the X-7 we've manufactured.<br />
}}<br />
<br />
==Explanation==<br />
Patient Zero is the usual terminology for the first patient tested or infected with an outbreak-style infection.<br />
<br />
Also, it seems every zombie movie is rife with terrible mistakes which allow the slowly lurching zombies (or outbreak) to escape and spread. For example, the nurse will look at the chart and not look at the patient and then walk away. The security guard will cross the hall 2 seconds after the zombie has left the doorway.<br />
<br />
The situation in the comic sounds more realistic; blast the zombie, destroy the toxin and then go on a date.<br />
<br />
==Transcript==<br />
:[Two scientists, Ryan and Laura, stand outside a lab. A zombie is visible through the window.]<br />
:The outbreak started with Patient Zero...<br />
:Ryan: He was exposed to toxin X-7—now he's a bloodthirsty monster!<br />
:Laura: Has he been in isolation?<br />
:Zombie: Braaains!<br />
<br />
:Ryan: Yes, but I can't hold this door for long!<br />
:Laura: Hang on, I've got a gun in my truck.<br />
:[She runs off.]<br />
:''wham''<br />
<br />
:[Ryan opens the door as Laura shoots through it.]<br />
:''BLAM''<br />
<br />
:And ended with Patient Zero five minutes later.<br />
:Ryan: So, I never got your name. I'm Ryan.<br />
:Laura: Laura.<br />
:The remaining 90 minutes of the movie will be a romantic comedy.<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics with color]]<br />
[[Category:Zombies]]</div>173.245.54.190https://www.explainxkcd.com/wiki/index.php?title=1204:_Detail&diff=726211204: Detail2014-07-31T14:25:17Z<p>173.245.54.190: /* Explanation */ Corrected 'exponentially' to 'linearly'.</p>
<hr />
<div>{{comic<br />
| number = 1204<br />
| date = April 26, 2013<br />
| title = Detail<br />
| image = detail.png<br />
| titletext = 2031: Google defends the swiveling roof-mounted scanning electron microscopes on its Street View cars, saying they 'don't reveal anything that couldn't be seen by any pedestrian scanning your house with an electron microscope.'<br />
}}<br />
<br />
==Explanation==<br />
{{w|Google Earth}} is a mapping software service provided by Google that allows people to view the Earth from above. If zoomed in to maximum magnification, one can obtain clear views of individual streets and homes.<br />
<br />
An image's {{w|Optical resolution|resolution}} is the smallest length detectable in that image. In terms of Google Earth, this refers to the real-life distance corresponding to one pixel in an aerial image. [[Randall]] points out that the level of detail in Google Earth's images has been increasing linearly since its introduction, as aerial imaging technology improves and better ways of collecting the data are found. Each tick in the scale represents a resolution improvement by 1000 times.<br />
<br />
In {{w|quantum mechanics}}, the {{w|Planck length}} is (in layman's terms) the smallest measurable distance, defined as approximately 1.6×10<sup>−35</sup> meters, or around 10<sup>20</sup> times smaller than the diameter of a proton. As the graph indicates, this may be called the "resolution" of the universe.<br />
<br />
Randall extrapolates the exponential trend of Google Earth's increasing resolution, 'revealing' that by the year 2120 or so, Google Earth's resolution will approach and even possibly exceed the Planck length, an obviously fanciful and impossible idea. Current laboratory instruments cannot even get close to measuring the Planck length, barely able to reach the level of the atom.<br />
<br />
Other comics exploring unwarranted extrapolation include [[605: Extrapolating]], [[1007: Sustainable]] and [[1281: Minifigs]].<br />
<br />
The title text refers to controversy that Google received at one point regarding their use of vehicle-mounted {{w|Google Street View|Street View}} cameras to take images of streets and houses, and how such photography could constitute an invasion of privacy. Google defended itself by stating that the cameras can see nothing more than a pedestrian walking by. Given the trendline in this comic however, Google would need to produce resolution in the nanometer range by 2031, which (using today's technology) would require the use of {{w|scanning electron microscope}}s. The same 'invasion of privacy' defense would obviously not work here, as 1) current scanning electron microscopes in labs can only be used with small specimens at very close range, and are completely unsuitable for observing something as large as a house or for observations from a passing car, and 2) it is probably not too likely for the average pedestrian to be equipped with such a microscope.<br />
<br />
==Transcript==<br />
:My Neighborhood's Resolution in:<br />
:[A two-axis graph with years from 2000 to 2100 plotted on the x-axis and resolution from 1 meter to the Planck length plotted on a logarithmic scale on the y-axis. Three points in a line close to (~2010, 1 meter) are plotted at the bottom left of the graph; they have a strong positive correlation. Two trendlines are drawn on the graph; one is labeled "Earth" and remains constant at the Planck length over time; the other is labeled "Google Earth" and connects the aforementioned three points, extending upward in a straight line and approaching the Planck length around 2100. Both trendlines break up into question marks before the point they would intersect.]<br />
<br />
==Trivia==<br />
* An earlier version of this comic misspelled "neighborhood" as "neghborhood". This has since been corrected<!-- could someone update the image please?-->.<br />
<br />
{{comic discussion}}<br />
[[Category:Charts]]<br />
[[Category:Extrapolation]]<br />
[[Category:Google Maps]]</div>173.245.54.190