explain xkcd - User contributions [en]

461: Google Maps

2013-10-15T07:39:30Z

Jc86035: /* Transcript */

{{comic
| number = 461
| date = August 11, 2008
| title = Google Maps
| image = google_maps.png
| titletext = Apparently Google assumes you're traveling during the ferry's normal operating hours. We lost two hours circling that damn lake (to say nothing of the Straw Man).
}}

==Explanation==
{{w|Google Maps}} is a web mapping service application, which among other things, offers a route planner. The comic pokes fun at Google Maps for occasionally giving suboptimal directions, taking it to the logical extreme of giving directions that resemble the plot of a badly-scripted horror/action movie.

Luckily Cueball's brother realizes that the directions are weird when he notices that they're supposed to take a ferry after midnight. However, the title text implies that despite the bizarreness of the directions, the brothers still took them.

==Transcript==
:My road trip with my brother ran into trouble around page three of the Google Maps printout
:Google Maps Printout:
:<- 70. SLIGHT LEFT AT RT-22 -- GO 6.8 MI
:-> 71. TURN RIGHT TO STAY ON RT-22 -- GO 2.6 MI
:<- 72. TURN LEFT AT LAKE SHORE RD GO -- 312 FT
:-> 73. TURN RIGHT AT DOCK ST -- GO 427 FT
:[Water replaces an arrow.] 74. TAKE THE FERRY ACROSS THE LAKE -- GO 2.8 MI
:[A car is driving in the dark.]
:Cueball: Okay, now take dock st toward the ferry
:Brother: We're supposed to take a ferry? It's past midnight, and these woods are creepy.
:Cueball: Google maps wouldn't steer us wrong.
:[Cueball and brother stand outside the car. The ferry has a sign on it reading CLOSED.]
:[Cueball stands holding the google map print out next to brother in the dark]
:[Still standing in the dark]
:Cueball: Let me see those directions.
:Google Maps Printout:
:[Water replaces an arrow] 74. TAKE THE FERRY ACROSS THE LAKE -- GO 2.8 MI
:[A diagonal upward arrow] 75. CLIMB THE HILL TOWARD HANGMAN'S RIDGE, AVOIDING ANY MOUNTAIN LIONS -- UP 1,172 FT
:[A "u-turn" arrow] 76. WHEN YOU REACH AN OLD BARN, GO AROUND BACK, KNOCK ON THE SECOND DOOR, AND ASK FOR CHARLIE -- GO 52 FT
:[A van] 77. TELL CHARLIE THE DANCING STONES ARE RESTLESS. HE WILL GIVE YOU HIS VAN. -- CAREFUL
:[A picture of the straw man] 78. TAKE CHARLIE'S VAN DOWN OLD MINE ROAD. DO NOT WAKE THE STRAW MAN. -- GO π MI
:<- 79. TURN LEFT ON COMSTOCK. WHEN YOU FEEL THE BLOOD CHILL IN YOUR VEINS, STOP THE VAN AND GET OUT. -- GO 3.2 MI
:[Down arrow] 80. STAND VERY STILL. EXITS ARE NORTH, SOUTH, AND EAST, BUT ARE BLOCKED BY A SPECTRAL WOLF. -- GO 0 FT
:[A picture of a spectral wolf] 81. THE SPECTRAL WOLF FEARS ONLY FIRE. THE GOOGLE MAPS TEAM CAN NO LONGER HELP YOU, BUT IF YOU MASTER THE WOLF, HE WILL GUIDE YOU. GODSPEED. -- GO ?? MI.

{{comic discussion}}
[[Category:Comics featuring Cueball]]

1224: Council of 300

2013-10-15T07:33:38Z

Jc86035: /* Transcript */

{{comic
| number = 1224
| date = June 12, 2013
| title = Council of 300
| image = council_of_300.png
| titletext = 'And hypnotize someone into thinking they've uploaded it and passed it around.' 'But then won't the uploader get suspicious that it pauses at 301+ for a while? Why don't we just forge the number entirel--' ::BLAM:: 'The Council of 299 is adjourned.'
}}

==Explanation==
{{incomplete}}
{{w|YouTube}} (a video sharing site) has an odd quirk in its view counter. When a video hits 301 views, the view counter briefly stops updating. This means that YouTube is checking the views to make sure that no foul play is going on. (The choice of the number 301 is due to a harmless off-by-one error; Numberphile produced a [http://www.youtube.com/watch?v=oIkhgagvrjI video] that explains all this very well.) At times the number 301 catches some YouTubers off guard — for very popular videos, it may appear that the video has more likes than views!

More recently YouTube added a "301+" to indicate that the video has reached the 301 point and is awaiting review.

The author plays with the near coincidence of this number, and a conspiracy theory entity known as "The Committee of 300". "''The Committee of 300 aka The Olympians is a conspiracy theory which alleges the existence of a group founded by the British aristocracy in 1727. Proponents believe the Committee to be an international council which organizes politics, commerce, banking, media, and the military for centralized global efforts.''" [http://en.wikipedia.org/wiki/Committee_of_300 Wikipedia Article]

==Transcript==
:[A secret society meets in a darkened chamber; a kitschy video involving two people and an RC helicopter is projected onto the background.]
:Master: ..then it is settled. We the 300 members of the Secret Council decree that this video meets our standards and shall "go viral".
:Master: send it to one of our agents to be leaked to the common folk.
:Steward: Some of them are noticing the number.
:Master: ..add a plus sign to throw them off.
:Steward: very well.
:Soon...
:[A communication sent to Cueball, one of the many unsuspecting plebeians of the world.]
:Email: Ooh! check out this great video I found!
:[Zoom in on the viewer count of a YouTube video.]
:301+

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Internet]]
[[Category:YouTube]]

977: Map Projections

2013-10-15T07:27:40Z

Jc86035: /* Explanation */

{{comic
| number = 977
| date = November 14, 2011
| title = Map Projections
| image = map_projections.png
| titletext = What's that? You think I don't like the Peters map because I'm uncomfortable with having my cultural assumptions challenged? Are you sure you're not ... ::puts on sunglasses:: ... projecting?
}}

==Explanation==
{{w|Map projection}}, or how to represent the spherical Earth surface onto a flat support (paper, screen...) to have a usable map, is a long-time issue with very practical aspects (navigation, geographical shapes and masses visualization, etc.) as well as very scientific/mathematical ones, involving geometry or even abstract algebra among other things. There is no universal solution to this problem, any 2D map projection will always distort in a way the spherical reality; many projections have been proposed in various contexts, each intending to minimize distortions for specific uses (for nautical navigation, for aerial navigation, for landmass size comparisons, etc.) but having drawbacks from other points of view. Some of them are more frequently used than other in mass media and therefore more well-known than others, some are purely historical and now deprecated, some are really obscure, etc.

[[Randall]] suggests here the idea that someone's "favorite" map projection can reveal aspects of their personality, and goes through a series of them and what they can mean:

;Mercator
:The {{w|Mercator projection}} was introduced by Flemish cartographer Gerardus Mercator in 1569. The main purpose of this map is that at any point the vertical and horizontal scales are the same, so locally i.e. considering only a small part of the map, geographical features (shapes, angles) are well represented, which helps a lot in recognizing them on-the-field, or for local navigation in that small part only. For this reason that projection (or a close variant) is used in several online mapping services such as Google Maps, which means that people commonly see it nowadays. No angle distortion also means that a straight line on the map corresponds to a course of constant bearing (direction), which was very useful for nautical navigation in the past (and thus made that projection very well-known).

:However from a global point of view, this projection is radically incorrect in how it shows the size of landmasses (for instance Antarctica or Greenland seem gigantic), and furthermore, it always excludes a small region around each pole (otherwise the map would be of infinite height), so it doesn't provide a complete solution for the problem of map projection. The comic implies that people who like that projection aren't very interested with map issues, and typically use what they are offered without thinking a lot about it.

;Van der Grinten
:The {{w|Van der Grinten projection}} is not much better than the Mercator. It was adopted by {{w|National Geographic}} in 1922 and was used until they updated to the Robinson projection in 1988.

:The Van der Grinten projection is circular as opposed to the Mercator projection. Circles look happier than squares, leading to the conclusion that people who like the projection are optimistic.

;Robinson
:The {{w|Robinson projection}} was developed by {{w|Arthur H. Robinson}} as a map that was supposed to look nice. National Geographic moved to this projection in 1988, and used it for ten years, moving to the Winkel-Tripel in 1998.

:{{w|The Beatles}} was a rock band that enjoyed great commercial success in the 1960s. The Beatles, coffee, and running shoes suggest an ordinary, easygoing lifestyle paralleled by the projection.

;Dymaxion
:Also called the Fuller Map, the {{w|Dymaxion Map}} takes a sphere and projects it onto an icosahedron, that is a polyhedron with 20 triangular faces. It is far easier to unwrap an icosahedron than it is to unwrap a sphere into a 2D object and has very little skewing of the poles.

:Randall associates the projection to geek subculture and niche markets:
:*{{w|Isaac Asimov}} was an American science-fiction writer, that (as well as publishing many textbooks) is considered the father of the modern concept of robots. He invented the {{w|Three Laws of Robotics}}. He also worked on more than 500 books throughout his career.
:*{{w|XML}} is the eXtensible Markup Language. It is used to represent data in a format that machines can read and understand, as well as being human-readable. In practice, XML is cumbersome to read.
:*{{w|Vibram FiveFingers|Toed-Shoes}} are a [[1065|favorite]] of Randall's to pick on. In society they are seen as a {{w|geek}} clothing item.
:*Brought to the world by {{w|Dean Kamen}}, the {{w|Segway PT}} was supposed to be a device that changed the way cities were built. In reality, most principalities have put in place rules specifically against Segways, making them a frustration to own and use within the law (in some states in Australia, it is illegal to use them on public footpaths or roads). Also, the former owner of {{w|Segway Inc.}}, the late {{w|Jimi Heselden}}, accidentally rode his Segway off a cliff in 2010.
:*{{w|Virtual reality|3D goggles}} are a very niche market only pursued by enthusiasts. In the 1990s the promise of virtual realities was very tantalizing; many companies attempted to perfect it, but fell short of the mark. Also, the phrase "The grass is always greener on the other side of the fence." is relevant.
:*{{w|Dvorak Simplified Keyboard|Dvorak}} is an alternate keyboard layout to QWERTY. Where QWERTY was invented to help keep manual typewriters from jamming (by placing the most used keys further away from each other), Dr. {{w|August Dvorak}} performed many studies and found the mathematically optimal keyboard layout to reduce finger travel for right handed typists. While technically better than QWERTY, QWERTY had become the standard. All the keyboards were laid out in QWERTY format, and retraining the brain after becoming a touch typist is extremely difficult.

;Winkel Tripel
:Proposed by {{w|Oswald Winkel}} in 1921, this map tried to reduce the three (German: tripel) main problems with map projections: area, direction, and distance. The {{w|Kavrayskiy VII projection|Kavrayskiy projection}} is very similar to the Winkel Tripel and was used by the USSR, but very few in the Western world know of it.

:The comic links this projection to {{w|hipster}} subculture. The whole point of hipsters is to avoid conforming to mainstream fashions. "Post-" refers to a variety of musical genres such as {{w|post-punk}}, {{w|post-grunge}}, {{w|post-minimalism}}, etc. that branch off of other genres.

;Goode Homolosine
:The {{w|Goode homolosine projection}} takes a different approach to skewing a sphere into a roughly circular surface. An orange peel can be taken off of an orange and flattened with fair success; this is roughly the procedure that {{w|John Paule Goode}} followed in creating this projection.

:Common people make arguments that if normal people would run the United States, then the US wouldn't be in the trouble it is. This is from the belief that career politicians are simply out to make money and will only act in the interest of their constituency when their continued easy life is threatened (usually around election time).

:Airline food is another, much maligned, problem. How do you store enough food to feed people on long airplane trips? The common solution is to use some kind of sub-standard microwaveable dinner. Randall is saying that the people in favor of the Goode Homolosine wonder why the airlines don't simply order meals from the restaurants in the airport, store that food, and serve it, rather than using frozen and microwaved food.

:Older cars burned oil like mad fiends and oil back then would become corrosive to the innards of an engine, so oil had to be changed often. But, with the introduction of synthetic motor oil and better designed engines, new cars only need their oil changed about ever 10,000 to 15,000 miles. Allegedly. Perhaps this is a conspiracy built by the collusion of the car manufacturers and big oil companies!

:All of these references suggest that people who like the Goode Homolosine projection are fans of easy solutions to problems. However, the solutions would not necessarily work in practice. For instance, the restaurants might have trouble making enough food for the whole plane, and it could get cold before being served. Also, the air conditions [http://www.nbcnews.com/health/one-reason-airline-food-so-bad-your-own-tastebuds-6C10823522 aboard planes] can affect taste, so airlines say they optimize for this.

;Hobo-Dyer
:The {{w|Hobo–Dyer projection}} was commissioned by Bob Abramms and Howard Bronstein and was drafted by Mick Dyer in 2002. It is a modified {{w|Behrmann projection}}. The goal was to be a more visually pleasing version of the Gall-Peters.

:As is discussed in the Gall-Peters explanation, the Gall-Peters was developed to be equal area, so that economically disadvantaged areas can at least take comfort in the fact that their country is represented correctly by area on maps.

:Randall associates the Hobo-Dyer projection to "crunchy granola" — a stereotype associated with vegetarianism, environmental activism, anti-war activism, liberal political leanings, and some traces of {{w|hippie}} culture.

:With the new general acceptance of homosexual, bisexual, and transgendered persons, some have begun to invent gender-neutral pronouns so that when referring to a person whose gender is not known they cannot be offended by being referred to by the wrong pronouns. In old English 'they' and 'their' were accepted gender-less pronouns that could replace 'he', 'she' as well as be used to represent a crowd. This usage is now considered archaic, so, a whole host of new pronouns are being invented in an attempt to keep from ever offending anyone ever again.

;Plate Carrée
:Also known as the {{w|Equirectangular projection}} that has been in use since, apparently, 100 AD. The benefit of this projection is that latitude and longitude can be used as x,y coordinates. This makes it especially easy for computers to graph data on top of it.

:According to the comic, the projection appeals to people who find much beauty in simplicity.

;A Globe!
:In any good discussion there has to be at least one smart-ass. This is a comic about map projections, that is, the science of taking a sphere and flattening it into 2 dimensions. The smart-ass believes that we shouldn't even try: a sphere is, in fact, the perfect representation of a sphere.

:To quote ''{{w|The Princess Bride}}'': "Yes, you're very smart. Shut up."

;Waterman Butterfly
:Similar to the Dymaxion, the {{w|Waterman butterfly projection}} turns a sphere into an octahedron, and then unfolds the net of the octahedron, which was devised by mathematician {{w|Waterman polyhedron|Steve Waterman}} based upon the work of {{w|Bernard J.S. Cahill}}

:Bernard Cahill published a [http://www.genekeyes.com/B.J.S._CAHILL_RESOURCE.html butterfly map] in 1909. Steve Waterman probably has the only extant "ready to go" map following the same general principles, though Gene Keys may not be far behind. Waterman has a poem with graphics in a similar vein to this xkcd comic that is worth reading.[http://watermanpolyhedron.com/worldmap.html]

:The Cahill/Keyes/Waterman projections are arguably the only map projections, thus far, that more or less equally balance the inevitable “all maps lie” distortions in size, shape and area.

:The joke is that the person responding deeply understands map projections; anyone who knows of this projection is a person that Randall would like to get to know.

;Peirce Quincuncial
:The {{w|Pierce quincuncial projection}} was devised by {{w|Charles Sanders Peirce}} in 1879 and uses {{w|complex analysis}} to make a {{w|conformal mapping}} of the Earth, that conforms except for four points which would make up the south pole.

:{{w|Inception}} was a 2010 movie about {{w|meta}} {{w|lucid dream}}ing. It has a complex story that is difficult to follow and leaves the viewer with many questions at the end, and almost needs to be watched multiple times to be understood.

:The human brain is not well developed to deal with oddly obvious things. One example is that everyone has a skeleton, but everyone is surprised when a bone pokes through the skin after it has been broken. Another is the fascinating complexity of the human hand, a machine that is amazingly complex driven by a complex interplay of electrical and chemical signals and yet is the size of the hand and is so useful.

;Gall-Peters
:The {{w|Gall-Peters projection}} is mired in controversy, surprising for a map. {{w|James Gall}} a 19th century clergyman presented this projection in 1855 before the {{w|British Association for the Advancement of Science}}. In 1967, the filmmaker {{w|Arno Peters}} created the same projection and presented it to the world as a "new invention" that put poorer, less powerful countries into their rightful proportions (as opposed to the Mercator). Peters played the marketing game and got quite a few followers of his map by saying it had "absolute angle conformality," "no extreme distortions of form," and was "totally distance-factual" in an age when society was very concerned about social justice. All of these claims were in fact false. The polar regions are horribly distorted, and south of the Mediterranean Sea is "taller" than it should be.

:Anyone who loves such a politically charged map that has become popular by way of marketing stunts, Randall would rather not have anything to do with.

The title text makes a joke that goes to the familiar meme from ''{{w|CSI: Miami}}'', in which the star, David Caruso starts on sentence, then [[:Category:Puts on sunglasses|puts on his sunglasses]] and then ends it with a corny pun. In this case the pun is on {{w|map projection}} and {{w|projection (psychology)|projection}} in psychology This internet meme has been mentioned previously by xkcd in comic [[626]] and possibly others.

==Transcript==
:What your favorite
:'''Map Projection'''
:says about you
:[All of these are organized as Title, a copy of the particular projection underneath, and what it says about you under that]

:*Mercator
:**You're not really into maps.
:*Van der Grinten
:**You're not a complicated person. You love the Mercator projection; you just wish it weren't square. The Earth's not a square, it's a circle. you like circles. Today is gonna be a good day!
:*Robinson
:**You have a comfortable pair of running shoes that you wear everywhere. You like coffee and enjoy The Beatles. you think the Robinson is the best-looking projection, hands down.
:*Dymaxion
:**You like Isaac Asimov, XML, and shoes with toes. You think the Segway got a bad rap. you own 3D goggles, which you use to view rotating models of better 3D goggles. you type in Dvorak.
:*Winkel-Tripel
:**National Geographic adopted the Winkel-Tripel in 1998, but you've been a W-T fan since ''long'' before "Nat Geo" showed up. You're worried it's getting played out, and are thinking of switching to the Kavrayskiy. You once left a party in disgust when a guest showed up wearing shoes with toes. Your favorite musical genre is "Post–".
:*Goode Homolosine
:**They say mapping the Earth on a 2D surface is like flattening an orange peel, which seems enough to you. You like easy solutions.You think we wouldn't have so many problems if we'd just elect ''normal'' people to Congress instead of Politicians. You think airlines should just buy food from the restaurants near the gates and serve ''that'' on board. You change your car's oil, but secretly wonder if you really ''need'' to.
:*Hobo-Dyer
:**You want to avoid cultural imperialism, but you've heard bad things about Gall-Peters. You're conflict-averse and buy organic. You use a recently-invented set of gender-neutral pronouns and think that what the world needs is a revolution in consciousness.
:*Plate Carrée (Equirectangular)
:**You think this one is fine. You like how X and Y map to latitude and longitude. The other projections overcomplicate things. You want me to stop asking about maps so you can enjoy dinner.
:*A Globe!
:**Yes, you're very clever.
:*Waterman Butterfly
:**Really? You know the Waterman? Have you seen the 1909 Cahill Map it's based— ...You have a framed reproduction at home?! Whoa. ...Listen, forget these questions. Are you doing anything tonight?
:*Peirce Quincuncial
:**You think that when we look at a map, what we really see is ourselves. After you first saw ''Inception'', you sat silent in the theater for six hours. It freaks you out to realize that everyone around you has a skeleton inside them. You ''have'' really looked at your hands.
:*Gall-Peters
:**I ''hate'' you.

{{comic discussion}}
[[Category:Charts]]
[[Category:Puts on sunglasses]]

857: Archimedes

2013-10-15T04:49:50Z

Jc86035: Someone has been using spell check on proper nouns...

{{comic
| number = 857
| date = February 7, 2011
| title = Archimedes
| image = archimedes.png
| titletext = Give a man a fish, or he will destroy the only existing vial of antidote.
}}

==Explanation==
This comic references a famous quote made by {{w|Archimedes}}: "Give me a place to stand on, and I will move the Earth". Here, [[Cueball]] starts off the quote, but then he turns this into a hostage situation, announcing to kill a hostage every hour until he got the equipment to move the Earth. His hostages are the entire population of the Earth.

The title text references a famous proverb, "Give a man a fish, and you feed him for a day. Teach a man to fish, and you feed him for a lifetime." But also here we have a hostage situation; if you do not give a fish to the man, he will destroy the only existing vial of antidote, which could stop Cueball's actions.

==Transcript==
:Cueball: In the words of Archimedes,

:Cueball: Give me a long enough lever and a place to rest it,

:[Cueball pulls out a gun.]
:Cueball: Or I will kill one hostage every hour.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Physics]]

305: Rule 34

2013-10-14T09:43:37Z

Jc86035: /* Trivia */ Well... !!!NSFW!!!

{{comic
| number =305
| date =August 20, 2007
| title =Rule 34
| image =rule 34.png
| titletext =Okay, Lance. For entry into the college bowl, spell 'Throbbing'
}}

==Explanation==
[[Cueball]] is rather surprised to find {{w|slash fiction}} (same-sex erotic fiction) featuring characters from the {{w|Thomas the Tank Engine}} television series, but [[Megan]] isn't remotely surprised, citing {{w|Rule 34 (meme)|Rule 34}}: "If it exists, there is porn of it. No exceptions."

Cueball denies the truism of the rule, coming up with several examples of porn that doesn't exist yet, until he comes across one that they both agree would be pretty hot: Women playing electric guitar in the shower. Megan proceeds to get ahead of the curve by registering [http://WetRiffs.com WetRiffs.com] ({{w|NSFW}}).
By doing this, Megan invoked {{w|Rule 35 (meme)|Rule 35}}, an amendment on rule 34. Rule 35 states: 'If there is not porn of it, porn will be made of it'.

==Transcript==
:Cueball: Huh-- Thomas the Tank Engine slash fiction.
:Megan: It's rule 34 of the internet. If you can imagine it, there is porn of it.
:Cueball: Nah. The web is freaky, but it can't begin to have everything.
:Cueball: There's no porn set atop storm-chasing vans. No homoerotic spelling bees. No women playing electric guitar in the shower.
:Megan: Actually, that last one would look pretty hot. As long as they were unplugged or waterproofed...
:Megan: Rivulets of water run down her chest, the smooth body of the guitar firm against her hips.
:Megan: She twangs the E-string and it shakes off tiny droplets in all directions.
:[She rises into a crouch.]
:Megan: You're sure it doesn't exist?
:Cueball: Not yet.
:Megan: I'm registering WetRiffs.com. Let's get on this.

==Trivia==
*Randall actually ''did'' register [http://wetriffs.com Wetriffs.com] (archive [http://web.archive.org/web/20130518191217/http://wetriffs.com/ here]), and people submitted pictures of themselves in the shower holding electric guitars. Randall would later create a tumblr page called "[http://raccoonsexdungeon.tumblr.com Raccoon Sex Dungeon]" to coincide with Cueball referencing it in [[1025: Tumblr]].
*When referencing a fictional website on a webcomic, TV series or other form of media, it's generally a good idea to create the website yourself so that you can control the content and protect yourself from getting sued because someone got there first and flooded it with inappropriate, even harmful material.
*There is a comic about [https://inkbunny.net/submissionview.php?id=8430 homoerotic spelling bees].

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]

Template:LATESTCOMIC

2013-10-14T08:27:35Z

Jc86035: Little bit too much?

{{ #ifexist:1290|1290| {{ #ifexist:1289|1289| {{ #ifexist:1288|1288| {{ #ifexist:1287|1287| {{ #ifexist:1286|1286| {{ #ifexist:1285|1285| {{ #ifexist:1284|1284| {{ #ifexist:1283|1283| {{ #ifexist:1282|1282| {{ #ifexist:1281|1281| {{ #ifexist:1280|1280| {{ #ifexist:1279|1279| {{ #ifexist:1278|1278| {{ #ifexist:1277|1277| {{ #ifexist:1276|1276| {{ #ifexist:1275|1275| {{ #ifexist:1274|1274| {{ #ifexist:1273|1273| {{ #ifexist:1272|1272| {{ #ifexist:1271|1271|1270}} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }} }}

1047: Approximations

2013-10-11T16:56:45Z

Jc86035: /* Explanation */ No guitar strings then...

{{comic
| number = 1047
| date = April 25, 2012
| title = Approximations
| image = approximations.png
| titletext = Two tips: 1) 8675309 is not just prime, it's a twin prime, and 2) if you ever find yourself raising log(anything)^e or taking the pi-th root of anything, set down the marker and back away from the whiteboard; something has gone horribly wrong.
}}

==Explanation==
{{incomplete}}
This comic lists some approximations for numbers, most of them mathematical and physical constants. All of them work astonishingly well. There are reoccurring math jokes along the lines of, “3/5 + π/(7 – π) – √2 = 0, but your calculator is probably not good enough to compute this correctly”, which are mainly used to troll geeks. Those interested in number theory may easily compute that sqrt(2) is not even algebraic in the quotient field of Z[pi], which disproves the equality.

Furthermore, there are some useful approximations (which were even more useful in times before calculators) such as “pi is approximately equal to 22/7”.

[[Randall]] makes fun of both of these, using rather strange approximations (honestly: you may handle 22/7, but who can calculate in a sensible way with 99^8, let alone 30^(pi^e)?) to calculate some constants that are easy enough to handle in the decimal system, and stating such “slightly wrong” trick equations, one of which ''is'' actually correct (which may astonish only those who are not familiar with cosines).

There are a few cultural references in this comic:

* 998 and 698 are sexual references.
* “Rent Method” refers to the song “Seasons of Love” from the musical “{{w|Rent (musical)|Rent}}.” The song asks, “How do you measure a year?” One line says “525,600 minutes” while most of the rest of the song suggests the best way to measure a year is moments shared with a loved one.
* (202) 456-1415 was (at least during the Bush administration) the phone number for the White House switchboard. Randall's formula gives approximately 0.2024561415.
* Jenny's constant comes from Tommy Tutone's tune {{w|867-5309/Jenny}}. Randall's formula gives approximately 867.530901981685.
* {{w|42 (number)|42}} is, according to Douglas Adams' ''The Hitchhiker's Guide to the Galaxy'', the Answer to Life, the Universe, and Everything.

And here are some of the mathematical and physical ones, with Wikipedia links.

* Informally, the {{w|Planck constant}} is the smallest action possible in quantum mechanics.
* The {{w|fine structure constant}} indicates the strength of electromagnetism. It is unitless and around 0.007297, close to 1/137. At one point it was believed to be exactly the reciprocal of 137, and many people have tried to find a simple formula explaining this (with a pinch of {{w|numerology}} thrown in at times).
* In {{w|mathematics}}, the {{w|Euler-Mascheroni constant}} (Euler gamma constant) is a mysterious number describing the relationship between the {{w|Harmonic series (mathematics)|harmonic series}} and the {{w|natural logarithm}}.
* The {{w|gravitational constant}} relates to, uh, gravity.
* The {{w|gas constant}} relates energy to temperature in physics.
* ϕ is the {{w|golden ratio}}, or (1 + √5)/2. It has many interesting geometrical properties.
* The ruby laser wavelength varies because “ruby” is not clearly defined.
* The {{w|Earth radios#mean radii|mean earth radius}} varies because there is not one single way to make a sphere out of the earth. Randall's value lies within the actual variation of Earth's radius.

The correct equation in the "Pro tip - Not all of these are wrong" section is cos(pi/7) + cos(3pi/7) + cos(5pi/7) = 1/2 as [http://math.stackexchange.com/questions/140388/how-can-one-prove-cos-pi-7-cos3-pi-7-cos5-pi-7-1-2 shown here].

The number 8675309 at the title text refers to the song 867-5309/Jenny as mentioned above, causing a fad of people dialing this number and asking for "Jenny". The number is in fact a {{w|twin prime}} because 8675311 is also a prime. Twin primes have always been a subject of interest, because they are comparatively rare, and because it is not yet known whether there are infinitely many of them.

{{w|Pi}} is a natural constant that arises in describing circles or ellipses. As such, useful as it may be, it really shouldn't occur anywhere in an exponent (unless you deal with complex numbers).

Same goes for the e-th power: e typically appears in the basis of a power (forming the {{w|exponential function}}), not in the exponent.

==Transcript==
A table of slightly wrong equations and identities useful for approximations and/or trolling teachers. (Found using a mix of trial-and-error, Mathematica, and Robert Munafo's Ries tool.) All units are SI MKS unless otherwise noted.

*Relation: One light year(m) ~= 99^8
Accurate to within: one part in 40

*Relation: Earth Surface(m^2) ~= 69^8
Accurate to within: one part in 130

*Relation: Ocean's volume(m^3) ~= 9^19
Accurate to within: one part in 70

*Relation: Seconds in a year ~= 75^4
Accurate to within: one part in 400

*Relation: Seconds in a year (rent method) ~= 525,600 x 60
Accurate to within: one part in 1400

*Relation: Age of the universe (seconds) ~= 15^15
Accurate to within: one part in 70

*Relation: Planck's constant ~= 1/(30^pi^e)
Accurate to within: one part in 110

*Relation: Fine structure constant ~= 1/140
Accurate to within: [I've had enough of this 137 crap]

*Relation: Fundamental charge ~= 3/(14 * pi^pi^pi)
Accurate to within: one part in 500

*Relation: White House Switchboard ~= 1/(e^((1 + 8^(1/(e-1)))^(1/pi)))

*Relation: Jenny's Constant ~= (7^(e/1 - 1/e) - 9) * pi^2

----
Intermission: World Population Estimate which should stay current for a decade or two:

Take the last two digits of the current year

Example: 20[14]

Subtract the number of leap years since hurricane Katrina

Example:14 (minus 2008 and 2012) is 12

Add a decimal point

Example: 1.2

Add 6

Example: 6 + 1.2

7.2 ~= World population in billions.

Version for US population:

Example: 20[14]

Subtract 10

Example: 4

Multiply by 3

Example: 12

Add 10

Example: 3[22] million
----

*Relation: Electron rest energy ~= e/7^16 Joules
Accurate to within: one part in 1000

*Relation: Light-year(miles) ~= 2^(42.42)
Accurate to within: one part in 1000

*Relation: sin(60 degrees) = (3^(1/2))/2 ~= e/pi
Accurate to within: one part in 1000

*Relation: 3^(1/2) ~= 2e/pi
Accurate to within: one part in 1000

*Relation: gamma(Euler's gamma constant) ~= 1/(3^(1/2))
Accurate to within: One part in 4000

*Relation: Feet in a meter ~= 5/(pi^(1/e))
Accurate to within: one part in 4000

*Relation: 5^(1/2) ~= 2/e + 3/2
Accurate to within: one part in 7000

*Relation: Avogadro's number ~= 69^pi^(5^(1/2))
Accurate to within: one part in 25,000

*Relation: Gravitational constant G ~= 1/(e^((pi - 1)^(pi + 1)))
Accurate to within: one part in 25,000

*Relation: R(gas constant) ~= (e+1) * (5^(1/2))
Accurate to within: one part in 50,000

*Relation: Proton-electron mass ratio ~= 6*pi^5
Accurate to within: one part in 50,000

*Relation: Liters in a gallon ~= 3 + pi/4
Accurate to within: one part in 500,000

*Relation: g ~= 6 + ln(45)
Accurate to within: one part in 750,000

*Relation: Proton-electron mass ratio ~= (e^8 - 10)/phi
Accurate to within: one part in 5,000,000

*Relation: Ruby laser wavelength ~= 1/(1200^2)
Accurate to within: [within actual variation]

*Relation: Mean Earth Radius ~= (5^8)*6e
Accurate to within: [within actual variation]

----
Protip - not all of these are wrong:

*2^(1/2) ~= 3/5 + pi/(7-pi)

*cos(pi/7) + cos(3pi/7) + cos(5pi/7) ~= 1/2

*gamma(Euler's gamma constant) ~= e/3^4 + e/5

*5^(1/2) ~= (13 + 4pi)/(24 - 4pi)

*sigma(1/n^n) ~= ln(3)^e

{{comic discussion}}
[[Category:Charts]]
[[Category:Math]]
[[Category:Physics]]
[[Category:Protip]]

Template:LATESTCOMIC

2013-10-11T11:05:58Z

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