explain xkcd - User contributions [en]

2338: Faraday Tour

2020-07-28T02:57:29Z

108.162.237.130: /* Transcript */ tap space bar

{{comic
| number = 2338
| date = July 28, 2020
| title = Faraday Tour
| image = faraday_tour.png
| titletext = I asked them if it was safe to be running tours during the pandemic. They said, "During the what?"
}}

==Explanation==
{{incomplete|Created by a FARADAY SUPERFAN. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

[[Hairy]], addressing an unseen camera (possibly the reader's POV) welcomes viewers to a {{w|Live streaming|livecast}} walk through "the world's largest {{w|Faraday cage}}." A Faraday cage blocks {{w|Electromagnetic field|electromagnetic transmission}} into and out of the cage area. Attempting to broadcast a walk through such a cage with any medium that uses radio waves would (theoretically, at least) cause the transmitter's signal to drop out completely, resulting in the loading wheel shown in panels three and four. Faraday cages do not necessarily have to be dark inside, as this one appears to be, but the darkness visually aligns with the concept of {{w|communications blackout}}, which is what Hairy's viewers experience while Hairy is in the cage.

"Smash that like (or subscribe, etc.) button" is a typical command given by YouTubers to watchers, asking to like the video or subscribe to their channel if they liked the video, ultimately to boost the creator's popularity.

The title text refers to COVID-19 pandemic of 2020. The joke is that, as they don’t get cell service in the cage, the owners would be unaware of global events. This implies for comedic effect that the owners and workers solely live inside the Faraday cage. However, they would still be able to receive news when they step out to welcome visitors or to have printed newspapers or magazines delivered.

==Transcript==
:[Close-up on Hairy]
:Hairy: Hey there superfans, welcome to the livecast!
:[Hairy walks toward an opening in a large building]
:Hairy: Got a real treat for you today: a tour of the world's largest Faraday cage! C'mon, let's check it-
:[two panels of a "loading" spinner]
:[Hairy exits the building]
:Hairy: -was ''so cool!'' Wow!! Thanks for coming along, and don't forget to smash that like button!

{{comic discussion}}

[[Category:COVID-19]]
[[Category:Comics featuring Hairy]]
[[Category:Physics]]

2322: ISO Paper Size Golden Spiral

2020-06-26T16:15:01Z

108.162.237.130: /* Explanation */ used unicode to make text look prettier

{{comic
| number = 2322
| date = June 19, 2020
| title = ISO Paper Size Golden Spiral
| image = iso_paper_size_golden_spiral.png
| titletext = The ISO 216 standard ratio is cos(45°), but American letter paper is 8.5x11 because it uses radians, and 11/8.5 = pi/4.
}}

==Explanation==
{{incomplete|Created by a GRAPHICS DESIGNER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

This comic strip is about how to annoy graphic designers and mathematicians, much like [[590: Papyrus]] and [[1015: Kerning]].

An easy way to annoy many mathematicians is to make fanciful claims about the {{w|Golden Ratio}}. It's been claimed, with varying levels of credibility, to be detectable in many natural and human-made situations, often with the dubious subjective claim that using the ratio in some particular way makes an image more "beautiful". The {{w|Golden Spiral}} is a spiral whose growth factor is this ratio; a common (though slightly geometrically inaccurate) way to illustrate the spiral is to draw curves through a set of squares whose side lengths shrink according to the Golden Ratio. The result looks rather like Randall's drawing here.

However, Randall hasn't used the Golden Ratio at all; he's just drawn a spiral (''not'' the Golden Spiral) through a common diagram showing the {{w|Paper_size#A_series|A Series}} of standard paper sizes, but in landscape instead of portrait (this diagram is commonly drawn in portrait). These papers aren't squares at all, but rectangles whose side lengths shrink by a factor of the square root of 2. Additionally, the paper sizes shrink by a factor of one half, so the area is filled in a geometric series. This is sometimes called a ''silver'' rectangle, although the {{w|Silver ratio}} is actually 1+√2. By mistaking the A Series for something connected with the Golden Ratio, ''and'' perpetuating the tradition of making dubious claims about the Golden Ratio, Randall has successfully annoyed both graphic designers and mathematicians.

The title text is a similarly themed joke, based partly on the fact that the US uses {{w|customary units}} while the vast majority of the rest of the world uses {{w|SI units}}. The 11/8.5 ratio is the length/width ratio of {{w|Letter (paper size)|US Letter}} paper, which is 11 inches by 8.5 inches (another common size in the United States is US Legal, which is 14" by 8.5"). The value of π/4 radians is indeed equal to 45 degrees, although Randall takes the cosine in one case and uses the raw angle in the other case in order to get a close coincidence of values. The width and length of A Series paper ({{w|ISO 216}}) is always given in whole millimeters, and the width/length ratio is very close to cos(45°) (which is 1/√2=0.707…) As for US Letter paper, 11/8.5 is not in fact close to π/4, but it’s possible that Randall meant to write 8.5/11 instead of 11/8.5 (the comic now shows 8.5/11 on xkcd.com -- looks like he corrected the error). To 4 decimal places, 8.5/11 = 0.7727 and π/4 = 0.7854.

In reality, the usage of radians vs. degrees is not a geographic or political decision, but generally is delineated by profession. Most engineering and science fields measure angles in degrees or fractions of degrees (arcseconds, or even milliarcseconds in fields like astronomy), while mathematicians and physicists generally use radians. Civil engineers may refer to the slope of a road by its {{w|Grade (slope)|grade}}, which is commonly expressed in terms of the tangent of the angle to the horizontal (either as a percentage or a ratio); for angles up to ~10°, this is close to the value of the angle in radians.

The difference between the "real" Golden Spiral squares and Randall's version is approximately either .2038 (for √2-1.6180…) or .08907 ((1/√2)-1.6180…), depending on which way you're counting. Either way, the difference would be very noticeable.)

The spiral shown is approximately a logarithmic spiral with a growth factor of √2, although it has been edited slightly to make it fit neatly inside the rectangles.
If the center of the spiral is at the origin, it may be graphed with r = C*2^(θ/π), for any positive constant C.

In [[1488: Flowcharts]] a golden spiral has been laid in over the chart. That {{xkcd|1488|comic}} is a link that goes to the [https://xkcd.com/spiral/ spiral] page on xkcd.

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

:[Caption inside panel:]
:The golden ratio is everywhere!

:[Picture of the ISO standard paper sizes (i.e. A1, A2, etc.) placed so that they fit together perfectly, overlaid with a spiral resembling that of the golden ratio]
:[A rectangle in landscape orientation with width= height*sqrt(2) is divided into two halves by a vertical line. The left half, a rectangle in portrait orientation, with height=width*sqrt(2), is labeled "A1". The right half (also portrait) is divided into two halves by a horizontal line; the rectangle above this horizontal line (landscape) is labeled "A2". Below this horizontal line there is a landscape rectangle which is divided into two portrait rectangles by a vertical line. The right half is labeled "A3", the left half is divided into two halves by a horizontal line. The lower half is labeled "A4", the upper half is divided again, with its left half labeled "A5". The series continues like this until "A10". ]
:[Symbolically: A1 -right,up- A2 -down,right- A3 -left,down- A4 -up,left- A5 -right,up- A6 -down,right- A7 -left,down- A8 -up,left- A9 -right,up- A10.]
:[A red spiral starts at the lower left corner of A1, passes through the upper right corner of A1 which is also the upper left corner of A2, continues through the upper right corner of A3, lower right of A4, lower left of A5, etc, and after passing through the lower right corner of A10 continues to what would be the lower left corner of A11 and the upper right corner of A12.]

:[Caption below panel:]
:How to annoy both graphic designers and mathematicians

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Math]]

Talk:2019: An Apple for a Dollar

2018-07-14T18:15:07Z

108.162.237.130:

Is this a reference to how shops in America don't include VAT in price labels?
(It's my first time trying to contribute to this so sorry if I get some format stuff wrong){{unsigned ip|141.101.107.132}}

:Yeah, Randall would love it in Europe! (you should sign your posts with <nowiki>~~~~</nowiki> though) --[[Special:Contributions/172.68.51.22|172.68.51.22]] 15:53, 13 July 2018 (UTC)

:It is a commentary on overly complex taxes and fees on things that really shouldn't have fees applied (I can think of hardly anything that really should have a fee applied, or be taxed really, but that's a political-philosophical discussion for another space-time coordinate) [[Special:Contributions/172.69.70.239|172.69.70.239]] 16:18, 13 July 2018 (UTC) Sam

:We call it sales tax, and it doesn't have the chaining-effect on every stage of production that VAT does, but yeah. It's rarely calculated into the sticker price. [[Special:Contributions/162.158.106.246|162.158.106.246]] 16:27, 13 July 2018 (UTC)

Is food taxed where Randall lives? It's not where I live and I was under the impression that it's not in most of the US. It's not uncommon for me to go to a store after working out and buying a protein bar for exactly $1. {{unsigned ip|162.158.63.22}}

:Living smack-dab in the center of the US and I can tell you that pretty much everything has a sales tax. [[Special:Contributions/172.69.70.239|172.69.70.239]] 16:18, 13 July 2018 (UTC) Sam
::Groceries, such as apples, should not be taxed, but I believe that processed foods are taxed. Actually, nevermind, this is state dependent: [https://blog.taxjar.com/states-grocery-items-tax-exempt/] [[Special:Contributions/172.68.46.137|172.68.46.137]] 16:27, 13 July 2018 (UTC)

:In my experience food is indeed taxed like everything else, but businesses will sometimes set the actual price of the item slightly below $1, such that the tax makes it cost exactly $1. The example that comes to mind is the soft-serve ice cream at IKEA. [[User:PotatoGod|PotatoGod]] ([[User talk:PotatoGod|talk]]) 16:31, 13 July 2018 (UTC)
::That has been my experience as well, although it varies by region. — AfroThundr <sup>([[User:AfroThundr3007730|u]] · [[User talk:AfroThundr3007730|t]] · [[Special:Contributions/AfroThundr3007730|c]])</sup> 16:37, 13 July 2018 (UTC)

The closest thing this can relate to a for a European is buying dinners or hotel rooms if you come from a corrupt East or Southern European country where "tourists tax" is a real thing and added out of nowhere on top of the regular price, because the regular price only have to include regular taxes.[[Special:Contributions/162.158.202.58|162.158.202.58]] 16:39, 13 July 2018 (UTC)

I'm thinking on the analysis I tentatively added to the explanation above. I assumed Megan was an engineer, but re-reading the comic ("Should I solve for something ??") I think it's more possible she no longer has to do math in her career, and is being portrayed as having a flashback to school again when she encounters a similar situation to her education. The examples are common in math and physics in grade school. It's hard for me to figure out in my head how to combine all the different interpretations, or which ones are likely wrong; it would be great if somebody could clean it up. If not, it's just a tiny wiki on the internet. [[Special:Contributions/172.68.54.160|172.68.54.160]] 18:25, 13 July 2018 (UTC)

Is this really a grocery store? I thought of it more as a coffee shop. Minimalist decor and whatnot. It's also one of those places where you would explain introductorily that you want just the apple. --[[Special:Contributions/108.162.237.130|108.162.237.130]] 18:15, 14 July 2018 (UTC)

explain xkcd:Editor FAQ

2018-06-01T17:43:14Z

108.162.237.130: /* How do I embed images here? */ fix typo

'''Frequently Asked Questions for editors'''

This FAQ is a short description about editing pages at this wiki. Please read this careful and when there are further questions do not hesitate to enter them into this [[Talk:Editor FAQ|talk page]].

For general questions please read first the MediaWiki help pages about [[mw:Help:Editing pages|Editing pages]] or look at the full overview here: [[mw:Help:Contents|Help Contents]]. You also can use your preferred search engine by entering "MediaWiki mytopic". Change mytopic to the theme you're searching for, i.e. "MediaWiki tables" will show you many useful sites about editing tables.

This FAQ focuses only on topics related to this specific Wiki.

==What is the general layout of a comic page?==
In general you don't have to care about this because the pages are generated by a bot nearly immediately after a new comic is released. If the bot fails please follow exactly the instructions here [[User:dgbrtBOT]] to do all the needed changes here.

The layout is always this:
*Comic ''picture'' with the ''title text'' below
*''Explanation''
*''Transcript''
*''Trivia'' (optional)
*''Discussion'' (embedded Talk page)
*List of non standard ''categories''

==What shall I write at the explanation?==
Everything is welcome as long as it explains the content of the comic. Everybody can edit here and when others disagree about your contributions they may change it.

==What is the format of the transcript section?==
The transcript should describe the content (think about talking to an impaired person) in a compact manner and all written words. Every line begins with an indent (a simple : at the beginning) and every panel from the comic is separated by a blank line. The transcript must not contain any links. Also tables should be avoided, even when not all transcripts comply with this. Check older comics and you will understand.

==What belongs to the trivia section==
As the word says it's just not important odds-and-ends related to the comic. Since this wiki focuses on explaining this section is not part of the default layout.

==How do I behave at the talk page (discussion)?==
Everybody can add here any thoughts about the comic and more. Please follow the common netiquette and don't be rude. Every comment has to be signed at the end with <nowiki>~~~~</nowiki> or just click the sign button [[File:Button sig.png]] at the top of the editor.

==What does the incomplete tag mean?==
There are two templates to indicate that an explanation or the transcript do need further rework. Just enter <nowiki>{{incomplete|YOUR REASON}}</nowiki> or respectively <nowiki>{{incomplete transcript|YOUR REASON}}</nowiki> and don't forget to enter a proper reason. The reason at the transcript is not shown to the viewer.

==How do I enter links to other pages?==
The three mostly used options are:
*an internal link like <code><nowiki>[[Cueball]]</nowiki></code> which renders like this: [[Cueball]]
*a link to the English Wikipedia should use this template: <code><nowiki>{{w|Page}}</nowiki></code> links to the wikipedia article on "Page" or <code><nowiki>{{w|Page|Display}}</nowiki></code> prints "Display" which links to the wikipedia article on "Page"
*other external links can be done in three ways:
**just write the uri and it will be shown like this: http://www.example.com
**put it into single brackets: <code><nowiki>[http://www.example.com]</nowiki></code> and you will see this [http://www.example.com] (please avoid this)
**and add a text: <code><nowiki>[http://www.example.com Example Homepage]</nowiki></code> everything after the first space is shown: [http://www.example.com Example Homepage]

==Why I can't upload pictures here?==
Only registered and trusted users can create pages or upload images. Trusted means that the user must have done a small amount of edits before.

==How do I embed images here?==
This Wiki isn't a picture book, use this feature only sparingly and reduce the size as much as possible. An example can be seen here: [[1400: D.B. Cooper]]. The syntax in this case is <code><nowiki>[[File:DBCooper.jpg|thumb|150px|Cooper]]</nowiki></code> and the picture is taken from Commons, the main source for Wikipedia images. The full syntax can be found at [[mw:Help:Images|MediaWiki]].

You also can upload pictures directly to this Wiki by using the [[Special:Upload]] link from the menu. But do not violate any copyright rules or it will be deleted. And when the picture is available at Commons there is no need to upload it here.

==The picture at xkcd was updated, how do I upload this here?==
Sometimes the initial picture at [[xkcd]] contains typos or other errors. When that has been fixed the comic picture here should also be updated. Save the picture from xkcd to your local PC but be careful, there are two versions available. We here use only the smaller version ''picture.png'' and not the larger one ''picture_2x.png''. So change <code><nowiki>https://imgs.xkcd.com/comics/picture_2x.png</nowiki></code> to <code><nowiki>https://imgs.xkcd.com/comics/picture.png</nowiki></code> when your browser shows the 2x version.

To update it here just click the image in the comic page and then click "Upload a new version of this file" below the file history. And please be patient, you wont see your upload immediately because it still comes from the cache at the server. But when you see your upload in the file history everything is OK. Just wait...

Talk:1877: Eclipse Science

2017-08-24T21:39:07Z

108.162.237.130:

I'm pretty sure his point was actually that in the modern day eclipses are pretty well understood, easy enough to travel to, and provide very little actually unique circumstances, so in reality there is very little scientific value at all. Just a really cool thing to see

[[Special:Contributions/162.158.75.10|162.158.75.10]] 15:56, 16 August 2017 (UTC)
:Yet still there are some aspects of eclipses such as shadow bands which are unexplained. There are some theories, but eclipses are rare enough, plus shadow bands don't occur with every one, so there is no definitive explanation yet.
:[[User:RChandra|RChandra]] ([[User talk:RChandra|talk]]) 18:56, 16 August 2017 (UTC)
::The explanation of [https://en.wikipedia.org/wiki/Shadow_bands shadow bands] on wikipedia seems pretty solid to me. [[User:Zmatt|Zmatt]] ([[User talk:Zmatt|talk]]) 11:51, 17 August 2017 (UTC)

To me the comic is poking fun at the idea the media (and by extension laypeople in general) perceive eclipses to be of great scientific importance and that scientists are excited about it for that reason. Note how his almost every utterance contains "science". Megan deftly deflects his attempts to put words in her mouth and remains resolute in her stance that eclipses are interesting to everyone on their face value but not necessarily more so to scientists that others. [[Special:Contributions/108.162.216.160|108.162.216.160]] 19:35, 16 August 2017 (UTC)Pat

I guess Randall is sad that people outside the band seem to have less interest in the eclipse, like shown in the previous comic, and that they might not wish to travel a few hours to see a once in a life time spectacle, or as he also feared in the last comic, try too late to get there and get stuck in the trafic jam outside the totality zone. Being in the 99.9999% dark part is nothing compared to being inside the zone being able to see the corona (the ring in the sky). Go and see it if you have any chance of doing so! --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 21:13, 16 August 2017 (UTC)

Should we make a new category for eclipse comics?[[Special:Contributions/162.158.214.58|162.158.214.58]] 11:53, 17 August 2017 (UTC)
:If he continues tomorrow and Monday maybe. There are so far only really two. The other two comics mentioned in the previous comic only briefly mentions the eclipse. So it is really only two comics so far. And they are not related in their individual subject. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:30, 17 August 2017 (UTC)
:: While I agree an Eclipse category would be uncalled for, this is the third comic I can think of without looking back further: 1868, 1876 and now 1877. If Randall continues the theme tomorrow / today and Monday, that's a total of 5. Maybe a post-eclipse comic on Wednesday, then I expect he'll be done on the subject unless something big happens (like a plane crash by the eclipse being in their eyes or something. we can blame Randall for that example coming to my mind, LOL!). 6 and done doesn't seem to warrant a category. :) [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 06:52, 18 August 2017 (UTC)
:::"Puts on sunglasses" got a category after three comics. [[Special:Contributions/162.158.238.11|162.158.238.11]] 09:31, 19 August 2017 (UTC)

The explanation claims, "While some astronomers might be testing elaborate hypotheses during an eclipse, for other scientists (eg. organic chemists and herpetologists) it is just a once in a long time (maybe even once in a lifetime) event which is visually interesting". This is at odds with the existence of several [http://www.reuters.com/article/us-solar-eclipse-usa-projects-idUSKCN1AX100?feedType=RSS&feedName=scienceNews| citizen science projects] encompassing not just astronomy but also atmospheric sciences and animal behaviour. [[Special:Contributions/162.158.111.241|162.158.111.241]] 13:00, 17 August 2017 (UTC)
:There's also a decent number of science experiments that are worth repeating mostly to take advantage of improved instruments and so people get to see them--which can also be considered under 'improved instruments,' if part of what you're doing this time is recording the entire procedure on video. [[Special:Contributions/108.162.237.130|108.162.237.130]] 22:38, 17 August 2017 (UTC)

While the eclipse may not provide very many more opportunities to advance scientific research and knowledge, it is a terrific opportunity for science teachers at the elementary level to demonstrate the basic science of orbits and positions of the Sun, Moon, Planets and Stars.
As well as an opportunity at the secondary level to talk about the laws of gravity and motion and how predictable it all is that we can calculate the exact path of an eclipse hundreds of years in advance. Too bad this is happening during summer vacation.
It is also the kind of event that excites children enough that they might consider pursuing a career in science.
So while astronomers may find it old news and not providing new research opportunities, there is still a lot of science teaching opportunity. [[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 12:36, 18 August 2017 (UTC)

So there's a couple points here:
*Public demonstration of previously performed science is not really the same thing as actual experimentation where the outcome is in doubt, the latter of which advances our understanding. So yes, you can show something to people who haven't observed it directly before, but then you're not using the word "science" in the same way as Megan.
*There actually are new [http://www.cbc.ca/news/world/while-millions-watch-the-eclipse-from-earth-nasa-observes-from-the-sky-1.4255242|new experiments] being performed, not just old experiments with a new audience or improved equipment.
*There is a tendency among non-scientists to underestimate the certainty of scientific or statistical results. Some examples are "you can't teach evolution as settled science because it's only a ''theory''" and more recently "this poll only sampled a thousand adults, which is 0.03% of Americans, so it's meaningless because we have no idea what the other 99.97% think". So scientists are expected to keep verifying and re-verifying fairly basic results. [[User:D5xtgr|D5xtgr]] ([[User talk:D5xtgr|talk]]) 16:29, 21 August 2017 (UTC)
:That last one is hilarious, for reasons I doubt you realize. Some of us here know how to get a proper population sample--and, well, with that poll? I don't even know where to ''start'' on the potential sources of error. 'Too small' should appear on the list several times, though, since a lot of the sources of error can be controlled for by simply adding to your sample. (Yes, yes, changing your sampling techniques will also do it, but it's just plain '''''easier''''' to add more people, so you start there.) This is actually part of why being able to replicate results matter--plus, the training in how to do it properly does give you a pretty good idea how to rig your poll to produce the desired results, and what to watch for when reading others' research. [[Special:Contributions/108.162.237.130|108.162.237.130]] 21:39, 24 August 2017 (UTC)

Talk:1877: Eclipse Science

2017-08-17T22:38:14Z

108.162.237.130:

276: Fixed Width

2017-08-01T00:56:51Z

108.162.237.130: /* Explanation */

{{comic
| number = 276
| date = June 13, 2007
| title = Fixed Width
| image = fixed_width.png
| titletext = I wish I knew how to quit this so I wouldn't have to quit you.
| imagesize =
}}

==Explanation==
Fixed width or {{w|monospaced font}} refers to the font used in old teletype terminals and {{w|instant messaging}} clients (often {{w|Courier (typeface)|Courier}}).

For two text lines to have the same length it's easier if they are in a monospaced font. For example, the following sentences are the same length in a monospaced font, but since we are using a {{w|proportional font}} those lengths are not exact (the third line is noticeably wider):
<font face="Times New Roman, Times">
:<rob> last night was nice
:<emily> the best i've had
:<rob> yeah it was AMAZING
</font>

The title is possibly a double reference, both to a monospaced font and to lines of the same length.

Initially, by mere chance, Emily's and [[Rob]]'s lines were exactly the same length. This made Rob want to continue the pattern.

That Rob feels forced to change what he wants to type to continue the pattern could be a symptom of {{w|obsessive–compulsive disorder}}.

Because of the monospaced font, any reply with 19 characters (including space) would have continued the pattern. In particular, "definitely for real" or "i actually love you!" would have worked.

==Transcript==
:[A man, Rob, is sitting at a computer. The text is an IRC-style transcript of a conversation, in a fixed-width font. He is text-messaging a girl he slept with named Emily; their messages read as follows:]
<pre>
<rob> hi
<emily> hey you
<rob> last night was nice
<emily> the best i've had
<rob> yeah it was AMAZING
<emily> ok, i have to ask
<emily> is this for real?
<emily> or is it just sex
<rob> definitely just sex
<emily> holy shit
<emily> are you serious?
<emily> you don't know how much that made
my stomach hurt
<emily> i want to cry
<rob> i'm sorry
<rob> i wanted to type 'i love you'
<rob> but our line lengths were syncing up
<emily> ...
<rob> and it would have broken the pattern
* emily has disconnected
</pre>

{{Comic discussion}}
[[Category:Comics featuring Rob]]
[[Category:Romance]]
[[Category:Sex]]

1785: Wifi

2017-01-13T14:42:38Z

108.162.237.130: /* Explanation */ Copyedit

{{comic
| number = 1785
| date = January 13, 2017
| title = Wifi
| image = wifi.png
| titletext = Further out to the right, it works correctly, but the reason it works still involves the word 'firmware.'
}}

==Explanation==
{{incomplete|Seems good, but could do with more. The ref to TV Problems title text seems far fetched.}}

The graph shows the supposed probability that a guest will be able to connect to the owner's {{w|Wi-Fi}}. The graph starts with people who cannot find the settings, followed by those who can connect. Finally, the large drop in the graph on the right-hand side is explained by "firmware." Firmware is programming which operates a device at the lowest level, typically stored in a {{w|ROM}} or an EEPROM/flash, but sometimes it is transferred from a CPU to a device at system boot time. In most systems this just works but in the case of more geeky operating systems, like GNU/Linux, or more esoteric hardware, it needs to be installed separately. Therefore there is a group of people who know what they are missing but are unable to overcome the issue to connect. The title text indicates that the curve recovers once users are more experienced, and ''can'' overcome said issue.

These computer issues have previously appeared in several xkcd comics, notably [[456: Cautionary]], where WiFi problems specifically are mentioned in the title text.

The apparent paradox of people knowing more about a subject also having more problems with it is also explored in [[1760: TV Problems]]; in the title text, the ones who are more likely to die from a skydiving accident are the ones who know the more about skydiving safety, but that is of course not because they cannot make it work, but rather because they make many more dives than regular people, thus increasing the overall risk in spite of their competence.

==Transcript==
:[A line graph with a curve that starts just left of the Y-axis above the middle of the axis. Then it increases slightly and stays almost stable on a long flat plateau before it falls off fast towards the right. Each axis ends in an arrow and has a label to the left of the Y-axis and below the x-axis. Over the curve there are three labels, pointing with one arrow to the two rising and falling parts, and three arrows to the center label above the plateau.]
:Y-axis: Probability houseguest will be able to connect to WiFi
:X-axis: Houseguest tech-savviness
:Left label: Can't find wifi settings
:Center label: Works fine
:Right label: Something involving the word "firmware"

{{comic discussion}}

[[Category:Line graphs]]
[[Category:Computers]]

1728: Cron Mail

2016-09-02T16:31:00Z

108.162.237.130: /* Explanation */

{{comic
| number = 1728
| date = September 2, 2016
| title = Cron Mail
| image = cron_mail.png
| titletext = Take THAT, piece of 1980s-era infrastructure I've inexplicably maintained on my systems for 15 years despite never really learning how it works.
}}

==Explanation==
On {{W|Unix}}-like systems, {{W|Cron|cron}} is a system program running in background which allows one to schedule jobs to run at well-defined time slots. It is conceptually the same software which has been used since, at least, the 1980s and is still heavily used in modern operating systems, for example in several {{w|Linux}} distributions. Many administrative tasks on servers can be automated with cron, like monitoring or updates. Most people administrating a server-like system with a UNIX-like operating system will therefore know it, at least the basics.

When one of these jobs produces output, that output is sent as an email to the user, using the {{w|Sendmail|sendmail}} program. A common situation on many Unix-like systems is that sendmail (or another email program) is not configured to send email to the actual email address of the person behind the user account that configured the cron job, and writes the mail in question to the file <code>/var/mail/username</code> (in {{w|Mbox|mbox}} format) instead. Most shells will check that file, and produce a message "You have new mail" when its timestamps have changed, however if a person doesn't know how to check their mail they will likely end up just ignoring that message.

The "/etc" directory is used for configuration files on UNIX-systems, therefore "/etc/crontab" is the main configuration file of cron and is expected to contain lines such as the following:

#m h dom mon dow user command
17 * * * * root cd / && run-parts --report /etc/cron.hourly

Comment lines are designated by a # and are ignored, as are blank lines. On a non-comment non-blank line, the first 5 parameters tell it exactly when that line is supposed to run (in this case every hour on the 17th minute of the hour), the next part is what user the command is supposed to run as (root in this case), and the rest is the actual command that is supposed to run (cd / && run-parts --report /etc/cron.hourly). The 5 time parameters, in order are minutes, hours, day-of-month, month, and day-of-week. A * means everything matches. So something could run as frequently as every minute (* * * * *) or as infrequently as once a year (i.e. January 2nd at 10:20am is 10 20 2 1 *). If a line that doesn't follow the correct format is added to /etc/crontab, it may cause the entire crontab file to be ignored, even those entries that are otherwise valid.

When a cron job runs, it is expected to do something with all text that might normally go to the screen -- a lot of times a command will redirect it to a log file of its own, or deliberately make it go nowhere (/dev/null). If anything does end up "on the screen", cron captures it and sends it as an email to the user, assuming it's data the user wants to view and be aware of. If local email is not configured to go somewhere the user actually knows to check, it usually ends up tacked on to the end of a file in /var/mail/username where it will sit forever, or until the user actually does something with it (either configures a local email program, sets up a forward to an email account they actually check, or deletes the file). Ponytail's suggestion to "fix the cron" means figure out why the cron job is outputting data to the screen, which is thus generating an email, and instead having the cron job handle its own messages in a better way. Once the cron jobs are no longer "talking" all the time, her further suggestion to point the MAILTO= to somewhere else would help Cueball be immediately aware if something goes wrong with a cron job that is normally quiet, so he can address the problem immediately instead of it going on for years undetected.

[[Cueball]] is not aware of all of the above, and expresses surprise at the repeated messages. [[Ponytail]] tells him to check check <code>/var/mail/cueball</code> which contains a lot of messages from cron from all those 15 years he used cron without properly understanding how it works.

When he realizes what has happened, he configures the mail system so that it writes all mail for his user to the <code>/etc/crontab</code> file, which is the main configuration file of cron (the <code>{{W|/etc}}</code> directory is used for configuration files on Unix-like systems), most probably breaking it. Of course, none of the jobs normally scheduled to run will run anymore either, so he will likely be surprised when other things that used to work no longer work. There are a number of system cron jobs that are usually present on Linux and Unix-like systems that one would not want to disable, including checking for updates, rotating log files including deleting old logs files, backups, etc.

In the worst case, cron might actually see the junk that [[Cueball]] is now directing into its configuration as valid configuration data and produce even more mail – resulting in a feedback situation that would eventually fill up the disk partition. It's unclear (especially to [[Cueball]]) whether this is actually possible – but it's certainly a risk.

The Title Text shows that Cueball is somewhat aware of what cron does, including the fact that it's existed pretty much unchanged for several decades, but he hasn't bothered to really get into understanding it, treating it more as a foe to vanquish rather than as a tool to understand and use.

==Transcript==
:[Cueball is sitting at a table in an office chair working on his laptop. Ponytail walks up to him.]
:Cueball: I've been getting these "You have new mail" UNIX notifications for like 15 years, but I've never bothered to figure out what it's talking about.

:[Ponytail has stopped behind Cueball who is typing on his laptop. When Ponytail (and later Cueball) mentions code, the text uses both small and capital letters (as opposed to only capital letters in all other text).]
:Ponytail: Look in /var/mail?
:Cueball: OK...
:Cueball: Oh, wow, there's like a gigabyte of stuff from Cron in here.

:[In a frame-less panel Ponytail is facepalming. Cueball is replying from off-panel with a starburst indicating his position.]
:Ponytail: *Sigh*
:Ponytail: You should fix your Cron, then point "MAILTO=" somewhere you actually see-
:Cueball (off-panel): Better idea:

:[Same setting as panel 2 but Cueball is visibly typing on the laptop as shown with three small curved lines over his hands on the keyboard.]
:Cueball: export MAILTO=/etc/crontab
:Cueball: There. Your move, Cron.
:Ponytail: Wow. Hardball.
:Cueball: Let's see how important it thinks that mail really is.

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Computers]]

Talk:115: Meerkat

2016-08-31T18:57:02Z

108.162.237.130:

"Quuuuiiiiet!! ... Theres NOTHing IN the RULEbook that SAYS an ELephant CAN'T. PLAY! Plllay ball!!!"
- Umpire regarding Bobo playing baseball, "Gone Batty" (1954) Looney Tunes [[Special:Contributions/152.119.255.250|152.119.255.250]] 16:40, 18 September 2013 (UTC)

But - rugby players don't wear helmets! Unlike a certain country's so-called "football" players ;)