explain xkcd - User contributions [en]

1837: Rental Car

2017-05-16T08:17:00Z

Archon 2488: leading zero

{{comic
| number = 1837
| date = May 15, 2017
| title = Rental Car
| image = rental_car.png
| titletext = Technically, both cars are haunted, but the murder ghosts can't stand listening to the broken GPS for more than a few minutes.
}}

==Explanation==
{{incomplete|Work in progress}}

In this comic the couple [[Megan]] and [[Cueball]] want to rent a car. The [[:Category:Multiple Cueballs|Cueball-like guy]] from the {{w|car rental}} agency tells them they only have two vehicles available:
* One car that puts its occupants into mortal danger, so much so that it is called ''The Murder Car''. The danger, however, is abstract – the car is haunted by a {{w|ghost}}, and actual death befalls only "maybe one in six". (That is the equivalent of a round of {{w|Russian Roulette}}.) This is the fatality rate for drivers (in this case, Megan), while the rate for passengers is not mentioned.
* The other car, a regular {{w|Sedan (automobile)|sedan}}, has a defective {{w|GPS}} that incessantly gives instructions to go specifically to {{w|Seattle}}, regardless of the driver's intention to go there. And it cannot be turned off.

Megan believes she can ignore this and accepts the least lethal car. The comic suggests that driving with a GPS that tries to guide you to a different destination than that which you wish to visit – so it is always recalculating and asking you to do U-turns – is incredibly annoying. So annoying that given the choice between the persistent low-level annoyance of the GPS on one hand, and the ("low") probability of being murdered on the other, most people will choose the latter option. After all, they might survive murderous ghosts but they feel they will not survive long having to listen to the broken GPS.

According to the title text, the murderous ghosts haunt both cars, but as soon as the car starts driving and the GPS begins to drone on, even the ghost cannot stand listening to the broken GPS and stops possessing it. It is possible that the title text is implying that the ghosts are actually responsible for the defective GPS, and by doing this, draw people into the only non-defective car available, the murder car.

Apart from the joke about GPS, there is also a joke on the horrible cars one might get at a car rental service...

==Trivia==
*With an estimated 1.25 million vehicular deaths globally in 2013[http://www.who.int/gho/road_safety/mortality/traffic_deaths_number/en/] and approx 53.7 million cars sold in the same year [https://www.statista.com/statistics/200002/international-car-sales-since-1990/], the number of fatalities per vehicle sold comes to be around 2.3% or about 1 in 43.5.
** The above number is an intentionally misleading statistic. See [[1102: Fastest-Growing]]
** (i.e. As of 2014, there were 253 million cars on the road in the US [http://www.latimes.com/business/autos/la-fi-hy-ihs-automotive-average-age-car-20140609-story.html] and only 32,675 deaths [https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/812246], giving a rate of fatalities per car of slightly over 0.01%, or 1 in 10,000)
***That equates to a reduction in risk by a factor of 99.56% over the course of a single year, perhaps due to the development of several new collision-avoidance systems in 2013. [https://www.forbes.com/sites/jimgorzelany/2012/05/03/hottest-new-car-features-for-2013/]

*The global number of haunted cars those with faulty GPS/Sat Navs is not available, but believed to be at least five in number. [http://www.autoblog.com/2014/10/31/five-cursed-haunted-cars/]

*There are records of several {{w|Death by GPS | deaths resulting from following faulty GPS directions or maps}}, particularly while traveling in unfamiliar or difficult terrain. [http://www.newser.com/story/214008/woman-killed-after-gps-takes-her-to-wrong-street.html] [http://www.npr.org/2011/07/26/137646147/the-gps-a-fatally-misleading-travel-companion] [https://arstechnica.com/cars/2016/05/death-by-gps/]

==Transcript==
:[A Cueball-like guy standing behind a desk looking at a computer screen services Megan and Cueball on the other side of the desk.]
:Guy: We have two rental cars left.
:Guy: One is the murder car. But don't let the name scare you!
:Guy: It's definitely haunted. But most drivers don't get murdered.
:Guy: Maybe one in six.

:[The guy lifts his hand and looks at Megan and Cueball.]
:Guy: The other is a regular Sedan.
:Guy: But it has a GPS that's stuck trying to navigate to Seattle.
:Megan: ...I can ignore it, right? That's fine.

:[In a frame-less panel Megan and Cueball drive in the Sedan.]
:GPS: Turn left
:GPS: Recalculating
:GPS: Make a U-Turn
:GPS: Recalculating
:GPS: Turn right
:GPS: Make a U-Turn
:GPS: Recalculating

:[Megan and Cueball walk back into the agency with the guy behind his desk. Megan holds out the car keys in one hand.]
:Guy: Back already?
:Megan: We'll take the murder car.
:Guy: Popular choice.

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Multiple Cueballs]]

1799: Bad Map Projection: Time Zones

2017-02-15T13:00:17Z

Archon 2488: grammar

{{comic
| number = 1799
| date = February 15, 2017
| title = Bad Map Projection: Time Zones
| image = bad_map_projection_time_zones.png
| titletext = This is probably the first projection in cartographic history that can be criticized for its disproportionate focus on Finland, Mongolia, and the Democratic Republic of the Congo.
}}
*A [http://imgs.xkcd.com/comics/bad_map_projection_time_zones_2x.png double sized version] of this image can be found by clicking the image at xkcd.com - the comic's page can also be accessed by clicking on the comic number above.
*Recent comics always have a larger (often the original) drawing using ''_2x'' added to the file name to indicate a different size. Modern browsers decide which resolution is shown. But at this comic the larger version is also clickable on the image. See much more details on this under the expanded explanation for the [[:Category:Large drawings|large drawings category]].

==Explanation==
{{incomplete|[[#Table of countries and their timezones|Table]] needs to be filled out for each country, both named and unnamed that are shown in the map with explanation of its timezone and why it looks as it does on the map. (Especially Russia, China and Greenland as well as those from title text needs explanation like that). Some of the info already given in the explanation could be moved to the table. Finally all labeled countries should be listed in the transcript as well.}}

This is the second comic in the series of [[:Category:Bad Map Projections|Bad Map Projections]]. The first was released just over a month before this one and was called [[1784: Bad Map Projection: Liquid Resize]].

Notably, "Liquid Resize" was #107, while this comic features #79, so either [[Randall]] has put them in a new arbitrary order or he is counting down from least to most terrible.

Conceptually, the series is a comment on the fact that there is no perfect way to draw a map of the world on a flat piece of paper. Each one will introduce a different type of distortion, and the best projection for a given situation is sometimes very disputed. Randall previously explored 12 different projections in [[977: Map Projections]], and expressed his disdain for some types he sees as less efficient but whose users feel superior. None of them are really good as any 2D map projection will always distort in a way the spherical reality, and a map projection that is useful for one aspect (like navigation, geographical shapes and masses visualization, etc.) will not be so for all the others. Local maps of smaller areas can be quite accurate, but the idea of both these map projection comics is to map the entire globe on a flat surface.

Randall, being Randall, runs with the idea. Has made yet another map projection that is not only inaccurate, but utterly unusable, though less so than the previous one.

This comic shows a {{w|Map projection|map projection}} in which countries are placed according to the {{w|Time zone|time zones}} that they fall under. Based on the way the Sun shines on the Earth, these time zones, which are based on the sun's position in the sky, would best be divided by roughly longitudinal (North-to-South Pole) lines.

However, this is not the case in practice, as the defined time zones tend to have very jagged boundaries. Since [[Randall]] knows he cannot fix the boundaries of the time zones, he instead "fixes" the world by making a map appear to match up with the time zone system. This results in bizarre distortions such as the large, gum-like strands of Greenland and enormous gulfs in parts of northern Russia.

The effect of this map is "punish" large countries with a single time zone - for instance, China, which uses UTC+8 across the whole country - and countries that share large time zones - for instance, almost all of Europe is packed into the Central European UTC+1 zone - by shrinking these down. Conversely, countries that span multiple time zones are stretched out - for example, the Democratic Republic of the Congo, as pointed out in the alt-text - as are those that belong to very small time zones - Finland and the Baltic states look huge because they are the only countries using the UTC+2 Eastern Europe time.

Other map projections distort countries this way as well, but based on their actual physical location as opposed to their position on imaginary time zones. The {{w|Mercator projection}} is infamous for distorting Greenland in this way, to the point that it appears to be larger than Africa despite being nowhere near the same size.

The title text lampoons the fact that the same phenomenon occurs on Randall's bad map projection, but for countries that do not tend to experience this on typical projections. Several smaller countries such as Finland, Mongolia, and the DRC, appear much larger than their actual size due to being stretched across time zone boundaries.

See the [[#Table of countries and their timezones|table]] below for lots more information on the comic, but here are some further details.

Some countries look especially odd. Greenland gets some jutting out points - these are the towns of {{w|Danmarkshavn}} (UTC) and {{w|Ittoqqortoormiit}} (UTC-1), which use different time zones to the rest of the island - while Russia gets big holes in it in places where there is a 2 hour time zone difference between states. For instance, in reality {{w|Komi}} and {{w|Khanty-Mansi}} touch each other. However, Komi uses Moscow time (UTC+3) and Khanty-Mansi uses Yekaterinburg Time (UTC+5). There is no state between them using UTC+4, so Randall draws a big gap in northern Russia here.

The map is imperfect since it doesn't allow for half-hour time zones (India, for instance, is on UTC+5.5). Instead, countries that use fractional time zones are shifted so they straddle the two time zones, and are then marked with an asterisk (*). There's also no mention of daylight savings - all countries shown are given the base winter time. Depending on the time of year, countries will shift around - around June, many northern hemisphere countries will move east, while some southern hemisphere countries will move east around December. Randall attempts to preserve adjacencies where possible - for instance, Chad and Sudan are neighbors even though Chad uses West Africa Time (UTC+1) and Sudan uses East Africa Time (UTC+3). Randall draws an extremely thin strand connecting the countries though Central/South Africa Time (UTC+2), even though no part of Chad or Sudan uses this time. Similarly, a thin strand of Kazakhstan and Turkmenistan is shown projecting into the UTC+4 time zone in order to separate Russia and Iran, which do not really share a border.

Australia has most of these peculiar timezone as there is a section in the center of Australia with half hour time zone, so it's marked with the *, but it is not the entire country, so the * is not behind the name as it is for instance with India. also the only extra detail mentioned in the map is for Australia. It is the {{w|UTC%2B08:45|UTC+8:45}} time zone that are listed. It is used only by 5 roadhouses in South Australia and Western Australia covering a population of only a few hundred people.

There are several labeling errors in the map. See [[#Errors|below]].

==Table of countries and their timezones==
*This table should include all countries not just those labeled.
**Also continents should be mentioned as they are also more or less distorted not necessarily depending on the distortion of the countries within.
*The labels used should be noted first, and the full country name (with wiki link) should be mentioned if abbreviations has been used in a bracket after.
*Timezone(s) for the country should be listed.
*Clear distortion shown in the image should be described
*Explanation for that based on timezone as well as other interesting details can be noted.

{| class="wikitable"
! Country/Continent
! Timezone(s)
! Distortions
! Explanation
|-
| Add more - just several examples made so far: || || ||
|-
| {{w|Europe}} (not labeled) || UTC+0 – UTC+3 || Compressed with the countries of central and western Europe pressed closer in east-west direction while eastern countries are stretched in all directions. ||
Portugal is the only country in mainland Europe which uses UTC+0 – that's why it sticks out a bit towards the British Isles which use UTC+0 as well. Iceland is here, too.

Most of Europe uses UTC+1 but these countries in reality spread over a much larger area than just one zone. This is why central and western countries are so compressed.

The eastern countries (except Belarus and the European part of Russia but not the Kaliningrad enclave) use UTC+2. These are: Finland, Latvia, Estonia, Lithuania, Belarus, Moldova, Ukraine, Bulgaria, Romania and Greece. In reality, they occupy a smaller area on the map, but on Randall's map they are stretched to fill the UTC+2 zone strip.

Belarus, most of the European part of Russia and Crimea use UTC+3. See below for peculiarities regarding Russia and Ukraine.

Finland looks specifically distorted, partly because in reality it borders with Norway on the north, and Norway uses UTC+1. On Randall's map Norway is compressed into UTC+1 strip and Finland suddenly got some coast on Barents Sea. Poland (abbreviated ''POL.'' on the map) and Belarus (''BEL'') have common border but differ by two time zones, Poland uses UTC+1 but Belarus uses UTC+3 (Moscow time). Therefore on the map they have protruding 'tongues', touching one another, squeezed between Lithuania and Latvia on the north and Ukraine on the south.

Randall got Turkey a bit wrong, however: its European part is stretched into UTC+2 zone, but in reality Turkey uses UTC+3 on its whole territory.
|-
| {{w|Greenland}}|| UTC-4 – UTC+0 || Two landmasses strechted from the rest of the country || Greenland stretches from UTC-4 to UTC+0 with most of the country being UTC-3. UTC-4 is only applicable to Thule Air Base in the southern part of the Hayes-Peninsula, UTC-1 and UTC+0 is used in smaller areas on the east coast of Greenland. Even though UTC-2 is not used in Greenland at all, the country is depicted as a single landmass with two small strips of land connecting the UTC-1 and UTC+0 landmasses. These two strips should be considered infinitesimally thin but depicted to clarify the two areas are not separate islands but connected with the rest of Greenland.
|-
| {{w|Iceland}} || UTC+0 || No shape distortions, but different location. || Iceland, even if it geographically lies mostly within the UTC-1 tome zone, uses UTC+0. It is therefore moved east on Randall's map.
|-
| {{w|Russia}} || UTC+2 – UTC+12 || Three deep troughs almost cutting Russia into pieces, but not quite, also eastern parts stick out of proportion relative to Eastern Asian countries. ||
Russia has {{w|Time_in_Russia|a peculiar}} usage of time zones, therefore it is the most distorted country on Randall's map. It covers eleven time zones but uses them very unevenly. Each of {{w|Federal subjects of Russia|federal subjects of Russia}} uses a specific time zone throughout its territory, but the assignments are somewhat arbitrary.

* UTC+2
* UTC+3
* UTC+4
* UTC+5
* UTC+6

|-
| UK ({{w|United Kingdom}}) || UTC+0 || None || The country is fully within the single time zone used for the country. UK defined the timezones so their time zone is by definition the one with UTC+0 (or GMT).
|-
| {{w|Ukraine}} || UTC+2 (UTC+3 in disputed regions) || Crimea stretched from the rest of the country || Since the {{w|annexation of Crimea by the Russian Federation}}, the peninsula has used Moscow time (UTC+3). The sovereignty of Crimea is disputed, but it is currently ''de facto'' controlled by Russia, and Randall colors it like Russia. Two breakaway provinces in the east, Donetsk and Luhansk, also use Moscow time. These are not shown.
|-
| Copy this line and the line above and set in directly under another entry || || ||
|}

==Transcript==
{{incomplete transcript|All the names on the countries}}
:[This transcript will note everything readable from the 2x zoom version found by clicking the comic on xkcd.]

:[Caption at the top of the panel:]
:Bad map projection #79:
:<big>Time Zones</big>
:Where each country '''''should''''' be, based on its time zone(s)

:[Below the caption there is a map of the world divided and colored by political boundaries, with outlines around each continent in black and around each country in dark gray. Antarctica is not included. Bodies of water are white, and countries in pale shades of red, orange, yellow, green, blue, and purple. The map is clearly distorted, with Europa and Africa in the center, but not all continents or countries looks wrong. Africa, Australia and North America seems least distorted. But the bottom part of of South America is very slim, Greenland has two chewing gum like blobs stretched away from it to the right, Iceland is over the UK, and most of Europe has been compressed. Finland though is too large. In Africa especially Dem. Rep. the Congo has been enlarged. The worst distortion is in Asia, where especially Russia looks weird with three deep troughs down the length of the country and the end to the right seems to be much longer than usually. But also China is completely wrong as it has been compressed, Mongolia taking up most of its usual position.]

:[Most countries over a certain size have their name listed in a gray font. Small countries like Ireland and Haiti has their name listed because it can be noted in the oceans around them. Most other countries have the name inside the country, but if there is not enough room abbreviation are used like Germany which has Ger. noted. There are though several small countries in the middle of Europa which has no name, as there are simply not enough space for even an abbreviation. This is countries like Belgium, The Netherlands and Denmark a long the coast towards England (with not enough Ocean space either for the name) and the small central countries like Austria, Switzerland and Luxembourg. There are also a few specialties mentioned when time zones are not divided in full hours, for instance a foot note regarding half hour time zones. Below all the mentioned countries will be listed starting from the left, going through each (political) continent from top left and down, and the same for each country in the continent:]

:[North America:]
:Canada
:United States
:Mexico
:Cuba
:Haiti
:Jam.
:D.R

:[Central America:]
:Gua.
:Hon.
:Nic.
:CR.
:Pan.

:[South America:]
:Columbia
:...
:
:Argentina

:[Europa:]
:Greenland
:Iceland
:Ireland
:UK
:Norway
:...
:
:
:Bulgaria

:[Africa:]
:W.S.
:Algeria
:Tunis
:...
:
:
:
:South Africa
:Madagascar

:[Asia:]
:Russia
:
:
:...
:Iran*
:Afghanistan*
:...
:
:...
:Russia
:...
:
:...
:India*
:Nepal*
:...
:Bur*
:...
:
:
:...
:China
:N.K*
:S.K.
:Japan

:[Oceania:]
:Malaysia
:Indonesia
:Philippines
:Papua New Guinea

:[Australia. In the country there is a star * in the middle of it above the name:]
:<nowiki>*</nowiki>
:Australia
:New Zealand

:[Below Australia there is an arrow pointing to a pointing the south cost and below that a foot note for the stars * used above:]
:UTC +8:45
:(One small area)
:<nowiki>*</nowiki>=Half-hour offset

===Errors===
* Randall mixes up Morocco and Western Sahara (a disputed territory)
* {{w|East Thrace}}, the European portion of Turkey, is shown in Eastern European time (UTC+2). Actually, like the rest of Turkey, it uses UTC+3

{{comic discussion}}

[[Category:Large drawings]]
[[Category:Comics with color]]
[[Category:Maps]]
[[Category:Bad Map Projections]]

1700: New Bug

2016-06-29T15:26:16Z

Archon 2488: caps

{{comic
| number = 1700
| date = June 29, 2016
| title = New Bug
| image = new_bug.png
| titletext = There's also a unicode-handling bug in the URL request library, and we're storing the passwords unsalted ... so if we salt them with emoji, we can close three issues at once!
}}

==Explanation==
{{incomplete|What is a resolvable URL? what is salting of passwords? Explain why the three issues can be closed with emoji salting}}

[[Cueball]] asks if an off-panel character can look at his bug report. The person asks if it's a "normal one" and not a "horrifying" one which "proves that the whole project is broken beyond repair and should be burnt to the ground". This implies that there have been reports of the "horrifying" variety in the past.

Cueball promises that it is a normal one but it turns out that the server crashes when a user's password is a resolvable URL, which implies that the server is in some way attempting to resolve passwords as if they were URLs. A resolvable URL is one that is syntactically correct and in particular includes a valid IP address or name, for instance "www.explainxkcd.com", in the <server-name> field; some might claim that it should also have a <path> field that is recognised by the server.

There is no reason for the code that processes passwords to attempt to resolve the input string as a URL, so any bug provoked by such input suggests a fundamental error in the way the server handles passwords. Realizing this, the off-panel person resigns and decides that burning the project to the ground is the only solution, telling Cueball ''I'll get the {{w|Butane|lighter fluid}}''.

In the title text another two issues with Cueballs program are mentioned together with a possible solution that would fix all three problems at once. The second problem is unicode-handling bug in the URL request library, and the third is that the passwords are stored unsalted. {{w|Salt (cryptography)|Salting}} passwords increases security by adding random data to the passwords which primarily helps defend against dictionary attacks.

The proposed solution is to salt the passwords with {{w|emoji}}, which is claimed to solve all three issues at once.

When the passwords are salted with emoji, the URL request library will fail to resolve any (salted) passwords due to its lack of unicode support. Since the server only crashes on ''resolvable'' URLs, this should mean the server won't crash anymore. In addition, the passwords will now be salted. Finally, emoji will often include unicode characters, which means that, if one can effectively salt passwords with emoji, then the passwords should be able to be stored in unicode (although that *probably* doesn't require anything outside the Base Multilingual Plane, so that might not need full unicode support after-all).

Given that this comic comes only five comics after [[1695: Code Quality 2]] is seems likely that the off-panel person is [[Ponytail]] and as could be seen in the first of those two comics, [[1513: Code Quality]], the perpetrator is indeed Cueball. In the title text of this first one, using emoji in variable names is mentioned.

In [[1349: Shouldn't Be Hard]] Cueball is also programming and finding it very difficult in-spite that he thinks is should be easy. An off-panel person suggest burning the computer down with a blowtorch much like the off-panel person in this one suggest burning the whole project (including the computer) to the ground with lighter fluid. In the very next comic, the multi storyline [[1350: Lorenz]], one [http://xkcd.com/1350/#p:2ed958de-badf-11e3-8001-002590d77bdd story line] results in a computer being [http://www.explainxkcd.com/wiki/images/a/a6/lorenz_-_laptop_9.png burned with a blow torch].

==Transcript==
:[Cueball sits at his desk in front of his computer leaning back and turning away from it to speak to a person off-panel.]
:Cueball: Can you take a look at the bug I just opened?
:Off-panel voice: Uh oh.

:[Zoom out and pan to show only Cueball sitting on his chair facing away from the computer, which is now off-panel. The person speaking to him is still of panel even though this panel is much broader.]
:Off-panel voice: Is this a '''normal''' bug, or one of those horrifying ones that prove your whole project is broken beyond repair and should be burned to the ground?

:[Zoom in on Cueballs head and upper torso.]
:Cueball: It's a normal one this time, I promise.
:Off-panel voice: OK, what's the bug?

:[Back to a view similar to the first panel where Cueball has turned towards the computer and points at the screen with one hand.]
:Cueball: The server crashes if a user's password is a resolvable URL.
:Off-panel voice: I'll get the lighter fluid.

{{comic discussion}}

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

1692: Man Page

2016-06-10T10:41:34Z

Archon 2488: /* Explanation */ grammar

{{comic
| number = 1692
| date = June 10, 2016
| title = Man Page
| image = man_page.png
| titletext = For even more info, see blarbl(2)(3) and birb(3ahhaha I'm kidding, just Google it like a normal person.
}}

==Explanation==
{{incomplete|The two synopsis lines has not been explained, including the fact that there seems to be missing ending "]" and "}" in both lines (although taken together as one line they actually have the correct amount of brackets, but that would not make sense - I guess?) Someone seems to think the explanation for the copyright is lacking and has left a [text in square bracket] above that explanation. Please imrpove of delete that text if explanation now OK. Needs fact-checking of the table etc.}}

This comic shows a {{w|Unix}} manual page, i.e. a ''{{w|man page}}'' (hence the title), for a fictional program called "blerp". It details the command line options for this program, many of which are strange, annoying, or even impossible. These options are in alphabetical order (putting lower case before upper case and with an em-dash inserted between b and c the only exception to this order).

Unix man pages are meant to provide a brief reference on the usage of a command, not verbose and well-written explanations as you may find in manuals which is another common type of documentation. This fictional man page seems to exaggerate its crypticness, thus making fun of a common trait that many man pages have.

{{w|Command-line_interface#Command-line_option|Command-line options}}, also known as flags, are typed following a program name to change how the program runs. The following is an example usage.

<code>blerp -a -d -t -p "AVIGNON"</code>

This would run blerp in attack mode, outputting to DEBUG.EXE, with tumble dry, and with POPE set to AVIGNON. In most cases, any number of flags can be used in any order, and applicable flags can be followed by arguments (such as "AVIGNON" in this example).

For a walk through of all possible flags see the [[#Table|table]] below.

Below the flags there are a ''see also'' list with other stupid program names. Apart from two more blerbs there is also blirb, blarb and blorb, with chapter references. The last blorp(501)(c)(3) is not a valid chapter reference for a man page, it is however a slightly covert reference to {{w|501(c)_organization|501(c)(3)}} which is an organization that is tax-exempt.

Then follows a bug report site. inaturalist.org is a site working to extend biological research, and http://www.inaturalist.org/taxa/47744-Hemiptera points to the same page as http://www.inaturalist.org/taxa/Hemiptera. {{w|Hemiptera}} is the order classifying True Bugs, making it the perfect place to report any new bug you have discovered...

[Copyright is a mishmash, "or best offer" is humorous, needs better explanation of individual parts.]

Finally there is a "{{w|copyright}}" line which references several variously open-source content licenses which is also a recurring theme on xkcd (see [[225: Open Source]]). For instance GPL references {{w|GNU General Public License}} and the (2) and (3+) refers to {{w|GNU_General_Public_License#Version_2|GPL 2}} and {{w|GNU_General_Public_License#Version_3|GPL 3 or higher}}. ''CC'' refers to {{w|creative commons}} where ''BY'' is the {{w|Creative_Commons_license#Types_of_licenses|type of license}}, ''5.0'' refers to the attribution and ''RV 41.0'' refers to revision 41.0. However there were no higher attribution than [https://creativecommons.org/licenses/by/4.0/legalcode 4.0] at the time of this comics release. xkcd is released under [http://creativecommons.org/licenses/by-nc/2.5/ CC BY-NC 2.5] as can be seen at the bottom of the {{xkcd}} homepage. A few comics have been released under the [[:Category:CC-BY-SA comics|CC-BY-SA license]] or [http://creativecommons.org/licenses/by-sa/3.0/ 3.0]. BSD refers to {{w|BSD licenses}} a [[:Category:BSD|recurring theme]] in xkcd . "LIKE GECKO" is a reference to a web browser user-agent string; modern user-agent strings include a lot of text designed to let the browser pretend to be several different browsers/renderers, and "(like Gecko)" is the standard text for a browser that wants to be treated as if it were {{w|Gecko (software)|Gecko}} while admitting, if you look closely, that it isn't really Gecko. This copyright line, which includes a lot of mashed-together text that might appear to match any of several different licenses, resembles a user-agent string.

"OR BEST OFFER" is a reference to an auction where the person who bids the highest gets to buy the item. In context, it suggest the person who has the highest offer for blerp will be sold the rights to the program. Since the other licenses mentioned would allow for free usage without paying royalties, it would usually be pointless to buy the rights to the program.

In the title text there is a list with even more info, again with crazy names like blarbl and birb. Again there are page references, but for the last the person writing this stops writing the reference and begins to laugh at who ever still reads this man page and telling them that he is kidding and suggest that they ''just Google it like a normal person''. Seems like [[Randall]] does not believe much in man pages anymore... The writer of this text thus also stops finishing the brackets as the ending ")" for the last chapter is missing.

Man pages were part of the subject of [[293: RTFM]] and were mentioned in [[456: Cautionary]].

===Table===
{| class="wikitable"
!Flag!!Description!!Explanation
|-
| -a||ATTACK MODE||This sounds like a command for a robot or something similar. Strange for a command line program. Possibly this is designed to break something?
|-
| -b||SUPPRESS BEES||Nonsensical option. This is a word play, meaning either to suppress {{w|Bee|Bees}} (the insects) or the letter '''B'''.
|-
| -—||FLAGS USE EM DASHES||Command line options (flags) typically use {{w|Hyphen|hyphens}} (short horizontal lines largely used within words). {{w|Dash#Em_dash|Em dashes}} (longer, with the same length as the letter "m") can't easily be typed into a command line interface, so switching flags from hyphens to em dashes is excessively difficult and nonsensical.
Also implies a paradox where if flags were to use em dashes, this flag itself would be invalid.
|-
| -c||COUNT NUMBER OF ARGUMENTS||Most likely not useful.
|-
| -d||PIPES OUTPUT TO DEBUG.EXE||{{w|DEBUG.EXE}} is the old 16-bit debugger that came with MS-DOS. On a Unix system it is much more likely that one would use the {{w|GNU Debugger}} (GDB). A debugger is usually called by calling the debugger with the program (or script) to be debugged as parameter.
{{w|Pipeline (Unix)|Piping}} in Unix means that the output of one program serves as input for another program.
|-
| -D||DEPRECATED||Many programs contain legacy options to avoid breaking scripts that use them. While the option should still work, the documentation is changed to say "deprecated" to discourage further use. Eventually such options usually get removed.
|-
| -e||EXECUTE SOMETHING||Vague. Also a possible pun on a kill-switch.
|-
| -f||FUN MODE||Strange and slightly ominous, given some of the other options. See under -O.
|-
| -g||USE GOOGLE||As an actual program flag, a bit hackjob-ish, but it is possible it is telling the user to use Google to find out what this tag does.
|-
| -h||CHECK WHETHER INPUT HALTS||Completely impossible, by the {{w|Halting problem}} which is the problem of determining, from a description of an arbitrary computer program and an input, whether the program will finish running or continue to run forever. {{w|Alan Turing}} proved in 1936 that a general algorithm to solve the halting problem for all possible program-input pairs cannot exist.
|-
| -i||IGNORE CASE (LOWER)||Usually, ignoring case means that a program will run without differentiating between upper- and lowercase. This flag suggests that blerp will run ignoring all the lowercase characters completely, or ignoring all the uppercase characters with the next flag "-I". Note that using this may make it ignore the difference for flags like -i and -I...
|-
| -I||IGNORE CASE (UPPER)||See above. Also possible that all text is converted to upper case, or that upper-case requirements only are ignored
|-
| -jk||KIDDING||A common acronym for [http://www.urbandictionary.com/define.php?term=jk Just Kidding], not a program flag. Also note that standard behavior of Unix command line options is that a single "-" can be followed by multiple one-letter options, making -jk equivalent to -j -k.
|-
| -n||BEHAVIOR NOT DEFINED||Possibly mathematically ominous? Otherwise useless.(Possible debug/unstable feature flag)
|-
| -o||OVERWRITE||Standard program flag, usually meaning that the program will overwrite a file rather than make a new one when data is output.May work strangely with -d.
|-
| -O||OPPOSITE DAY||Strange flag, possibly means that all other flags (or maybe even including this one!) have the opposite effects - if so, a lot of strange things would happen. (Especially with -b, -e, -f, -jk, -O...)
|-
| -p||SET TRUE POPE; ACCEPTS "ROME" OR "AVIGNON"||This refers to a {{w|Western_Schism|historical schism}} in the {{w|Catholic Church}}. In the 14th century, the Pope briefly ruled from Avignon, France, instead of Rome. After the Papacy was returned to Rome in 1377, the Church split (the so-called Western Schism) as not everyone accepted the move and the Pople who ordered it. This flag apparently allows the user to select a preferred Pope. There is actually a possible feature request here, as "PISA", a third Pope, should also be an option.
|-
| -q||QUIET MODE; OUTPUT IS PRINTED TO STDOUT INSTEAD OF BEING SPOKEN ALOUD||In most cases, a program will output basic information to the console, and running it in quiet mode will make it run without outputting anything. Blerp, on the other hand, outputs information through audio, and the quiet flag causes it to run like a normal program. "STDOUT" is short for "standard output".
|-
| -r||RANDOMIZE ARGUMENTS||Pointless and possibly damaging.
|-
| -R||RUN RECURSIVELY ON <nowiki>http://*</nowiki>||The star (*) symbol is often used as a wildcard to match any string of characters. "<nowiki>http://*</nowiki>" suggests that blerp will be run on every webpage on the internet, or on each page recursively. What it might do in order to make this valid is also ominous.
|-
| -s||FOLLOW SYMBOLIC LINKS SYMBOLICALLY||[Needs explanation of symbolic links] Many commands offer an option to follow filesystem links, this option however seems to suggest that it will only politely pretend to do so.
|-
| -S||STEALTH MODE||Similar to -a, in that it sounds more like an option for some kind of robot.
|-
| -t||TUMBLE DRY||Perhaps useful for a program that runs on a clothes dryer. Refers to [https://img1.etsystatic.com/000/0/5254504/il_570xN.184726893.jpg directions like these]. Many clothing items are marked "do not tumble dry" in the care instructions, but this would be extremely difficult to make relevant to a program. Given the other flags, this may be less nonsensical than it would first appear..
|-
| -u||UTF-8 MODE; OTHERWISE DEFAULTS TO ANSEL||{{w|ANSEL}} is an old and obscure character encoding that predates ASCII. Using ANSEL as a default would be strange and largely incompatible with most modern systems. On the other hand, UTF-8 is rather standard. Similar in this regard to -q, blerp does something non-standard by default. The problem with using different modes (where the original was also UTF-8) is shown in the title text of [[1683: Digital Data]].
|-
| -U||UPDATE (DEFAULT: FACEBOOK)||Update usually refers to replacing an old software with a newer version. The default here suggests posting a status update to Facebook, sourcing an update form Facebook, or updating Facebook itself.
|-
| -v||VERBOSE; ALIAS TO find / -exec cat {}||Almost standard flag, in ordinary programs the opposite of -q - instead of silencing output, it makes it more specific, usually to help with debugging. Instead, this flag gets replaced with a command that prints the contents of all files in the filesystem tree. However, it will never complete, as certain device files never end (/dev/urandom contains random bytes). Note that the "find" command is missing <code>\;</code> and will not run, instead complaining <code>find: missing argument to `-exec'</code> .
|-
| -V||SET VERSION NUMBER||Many programs will have a flag to view the version number. This flag changes the version number instead.
|-
| -y||YIKES||[[wiktionary:yikes|yikes]] is an interjection which can express fear or empathy with unpleasant or undesirable circumstances. It is unclear how this would influence the program.
|}

==Transcript==
:[A terminal screen; the background is black and the text is white.]
:{| class="wikitable"
|style="background-color:black;"|
;NAME
:blerp

;SYNOPSIS
:blerp {[ OPTION | ARGS ]...[ ARGS ... -f [FLAGS] ...}
:blerp {... DIRECTORY ... URL | BLERP} OPTIONS ] -{}

;DESCRIPTION
:blerp FILTERS LOCAL OR REMOTE FILES OR RESOURCES USING PATTERNS DEFINED BY ARGUMENTS AND ENVIRONMENT VARIABLES. THIS BEHAVIOR CAN BE ALTERED BY VARIOUS FLAGS.

;OPTIONS
:{|
! scope="row" | -a
| ATTACK MODE
|-
! scope="row" | -b
| SUPPRESS BEES
|-
! scope="row" | -—
| FLAGS USE EM DASHES
|-
! scope="row" | -c
| COUNT NUMBER OF ARGUMENTS
|-
! scope="row" | -d
| PIPES OUTPUT TO DEBUG.EXE
|-
! scope="row" | -D
| DEPRECATED
|-
! scope="row" | -e
| EXECUTE SOMETHING
|-
! scope="row" | -f
| FUN MODE
|-
! scope="row" | -g
| USE GOOGLE
|-
! scope="row" | -h
| CHECK WHETHER INPUT HALTS
|-
! scope="row" | -i
| IGNORE CASE (LOWER)
|-
! scope="row" | -I
| IGNORE CASE (UPPER)
|-
! scope="row" | -jk
| KIDDING
|-
! scope="row" | -n
| BEHAVIOR NOT DEFINED
|-
! scope="row" | -o
| OVERWRITE
|-
! scope="row" | -O
| OPPOSITE DAY
|-
! scope="row" | -p
| SET TRUE POPE; ACCEPTS "ROME" OR "AVIGNON"
|-
! scope="row" | -q
| QUIET MODE; OUTPUT IS PRINTED TO STDOUT INSTEAD OF BEING SPOKEN ALOUD
|-
! scope="row" | -r
| RANDOMIZE ARGUMENTS
|-
! scope="row" | -R
| RUN RECURSIVELY ON <nowiki>http://*</nowiki>
|-
! scope="row" | -s
| FOLLOW SYMBOLIC LINKS SYMBOLICALLY
|-
! scope="row" | -S
| STEALTH MODE
|-
! scope="row" | -t
| TUMBLE DRY
|-
! scope="row" | -u
| UTF-8 MODE; OTHERWISE DEFAULTS TO ANSEL
|-
! scope="row" | -U
| UPDATE (DEFAULT: FACEBOOK)
|-
! scope="row" | -v
| VERBOSE; ALIAS TO find / -exec cat {}
|-
! scope="row" | -V
| SET VERSION NUMBER
|-
! scope="row" | -y
| YIKES
|}

;SEE ALSO
:blerp(1), blerp(3), blirb(8), blarb(51) blorp(501)(c)(3)

;BUG REPORTS
:<nowiki>http://www.inaturalist.org/taxa/47744-Hemiptera</nowiki>

;COPYRIGHT
:GPL(2)(3+) CC-BY/5.0 RV 41.0 LIKE GECKO/BSD 4(2) OR BEST OFFER

|}

{{comic discussion}}

[[Category:Programming]]
[[Category:Computers]]
[[Category:BSD]]
[[Category:Animals]]

1489: Fundamental Forces

2015-02-20T12:16:14Z

Archon 2488: /* Explanation */ fix

{{comic
| number = 1489
| date = February 20, 2015
| title = Fundamental Forces
| image = fundamental_forces.png
| titletext = "Of these four forces, there's one we don't really understand." "Is it the weak force or the strong--" "It's gravity."
}}

==Explanation==
[[Cueball]] is acting here as someone teaching physics at a basic level, perhaps a high school science teacher. He seems to understand the general idea of the {{w|Fundamental interaction#Overview of the fundamental interaction|four fundamental forces}}, but his understanding gets progressively more sketchy about the details. The off-panel audience, probably a student or class, is interested, but quickly begins to realize Cueball's lack of understanding. Instead of acknowledging the problem directly, Cueball simply blusters onwards.

The comic also outlines how difficult to describe the forces progressively get. {{w|Gravitation|Gravity}} was first mathematically characterized in 1686 as {{w|Newton's law of universal gravitation}}, which was considered an essentially complete account until the introduction of {{w|general relativity}} in 1915. The {{w|Electromagnetism|electromagnetic force}} does indeed give rise to {{w|Coulomb's law}} of {{w|electrostatics|electrostatic}} interaction (another {{w|inverse-square law}}, proposed in 1785), but a much more comprehensive description, covering full {{w|Classical electromagnetism|classical electrodynamics}}, was only given in {{w|Maxwell's equations}} around 1861. The {{w|strong interaction|strong}} and {{w|weak interaction|weak}} forces cannot easily be summarized as comparably simple mathematical equations. It's possible that Cueball does understand the strong and weak interactions, but is completely at a loss when he tries to describe them.

The strong force doesn't act directly between protons and neutrons but between the quarks that form them. Unlike gravity and electromagnetism, the strong force grows ''stronger'' with distance. Between protons and neutrons there is a residual strong force, analogous in some ways to the Van der Waals force between molecules. This residual strong force is carried by pions and does decrease rapidly and exponentially with distance due to the pions having mass.

The weak force is much weaker than electromagnetism at typical distances within an atomic nucleus, and has a short range, so has very little effect as a ''force'', but has the property of changing one particle into another. It can cause an up quark to become a down quark, and in the process release a high energy electron and neutrino. This is known as beta decay, a form of radioactivity. Over even shorter distances the weak interaction and electromagnetism are essentially the same.

The title text refers to the fact that it is gravity that appears to be the simplest and easiest to understand of the four forces, but turns out to be the {{w|Graviton|hardest}} to reconcile with a coherent (quantum) understanding of all four forces together.

==Transcript==
Cueball: There are four fundamental forces between particles. (1) Gravity, which obeys the inverse square law, F_gravity=G(m_1 m_2/d^2)

Off panel audience: OK...

Cueball: (2) Electromagnetism, which obeys this inverse-square law: F_static = K_e (q_1 q_2 / d^2)
...and also Maxwell's Equations

Off panel audience: Also what?

Cueball: (3) The Strong Nuclear Force which obeys, uh ...
...well, umm...
...it holds protons and neutrons together.

Off panel audience: I see.

Cueball: It's strong.

Cueball: And (4) the Weak Force It [mumble mumble] radioactive decay [mumble mumble]

Off panel audience: That's not a sentence. You just said "Radio-

Cueball: –and those are the four fundamental forces!

{{comic discussion}}

[[Category:Physics]]