explain xkcd - User contributions [en]

Talk:381: Mobius Battle

2015-01-13T03:15:11Z

173.245.54.213: This trick is easy to do with 16mm cine film.

The gif should alternate left/right in order to properly portray the battle. [[Special:Contributions/184.66.160.91|184.66.160.91]] 06:48, 8 July 2013 (UTC)

: Look again, it does already! --[[Special:Contributions/83.243.48.2|83.243.48.2]] 08:20, 8 July 2013 (UTC)

Technically, there's only one guy. He passes through the comic twice for every one time the ball passes through. [[Special:Contributions/199.27.128.167|199.27.128.167]] 20:37, 17 December 2013 (UTC)

The explanation says "[the projectionist] would have no way to feed a Mobius strip film reel properly into a normal projector." That depends on how you define "normal". I just tried this on my grandfather's 16mm cine (film) and it worked fine. I cut ~300 frames from the start of a movie, twisted 180°, and spliced. Since my projector loads from the side it went in no problem and I used empty takeup reels to hold the loops. This wouldn't work on 8mm, though, cause the holes are only on one side. Can't speak to 35mm or IMAX film; I suspect not, because they have soundtracks, but I don't know for sure. Oh, I just thought of something to try with my 16mm loop; if I cut it in half lengthwise I should have a 600 half-frame 8mm loop, right? I'm not gonna try 'cause I don't have any way to cut down the middle in an exact enough way but that would be cool to try. Oh, and isn't it spelt Möbius? [[Special:Contributions/173.245.54.213|173.245.54.213]] 03:15, 13 January 2015 (UTC)

1160: Drop Those Pounds

2014-10-21T18:51:50Z

173.245.54.213: /* Explanation */ period used as decimal indicator in most English-speaking countries

{{comic
| number = 1160
| date = January 14, 2013
| title = Drop Those Pounds
| image = drop those pounds.png
| titletext = If the flyers don't work, we'll switch to the LEAST subtle method of informing a town of the existence of a trebuchet club.
}}

==Explanation==
The comic presents a flyer with text typical of a ubiquitous advertisement for a "Weight Loss Program". However, the image at the bottom of the flyer and the text below the flyer make it clear that the flyer is actually an advertisement for a trebuchet club. This unexpected meaning is meant to highlight the ambiguity of the flyer's content. A {{w|trebuchet}} is gravity powered siege engine, which was originally used to attack fortifications. It works by dropping a raised counter weight to rotate a throwing arm, launching a projectile on a ballistic path. The phrase "We'll help you hit your target by dropping 30 pounds FAST" is where the ambiguity is produced. In the context of a weight loss ad, the "target" would be a rhetorical device referring to the weight which one wishes to achieve. In the context of a trebuchet club, the target is a literal location which one is trying to hit with a projectile. Likewise, a weight loss ad may indicate that a client could quickly lose 30 pounds (~13.6 kg). However, in this context, the 30 pounds being dropped is either the counter-weight - which is dropped to provide a trebuchet with its power, implying a rather small trebuchet - or the projectile itself being dropped at the target - it will be slower than the counter-weight but definitely still much faster than any weight loss program.

The only hint that the flyer advertises a trebuchet club is in the drawing at the bottom of the flyer, which appears to show two individuals pondering a ballistic path towards a castle tower, though no trebuchet is shown.

The text below indicates that this flyer "may have been too subtle". The title text suggests that, if the flyer is indeed too subtle a form of advertisement, they will use the LEAST subtle options of announcing their club's existence — likely by using their trebuchet to attack the town.

See also [[382: Trebuchet]].

==Transcript==
:[We see a poster taped to a wall. It has Megan and Cueball in the bottom left, a silhouetted crenellated tower in the bottom right, and a thin arc between them. It reads:]
:Struggling with those 2013 resolutions?
:We'll help you hit your target
:By dropping thirty pounds '''fast'''
:[Small print.]
:WEB: http: [illegible].com
:CALL: (555) 123-4567

:The flyer for our trebuchet–building club may have been too subtle.

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

526: Converting to Metric

2014-10-13T17:32:53Z

173.245.54.213: /* Temperature */

{{comic
| number = 526
| date = January 5, 2009
| title = Converting to Metric
| image = converting to metric.png
| titletext = According to River, "adequate" vacuuming systems drain the human body at about half a liter per second.
}}
==Explanation==
Most people will eventually develop an intuitive feel for how big certain measurements are (e.g., how long an inch or a foot is, how much a pound weighs). This comic points out that people who were brought up using the {{w|Imperial measurement|imperial system}} probably don't have the same intuitive understanding for metric units and attempts to provide some benchmarks for these people. Most of the benchmarks are common sense, highly-useful ones (e.g., if it's 30 degrees centigrade [86 °F], you'd be quite comfortable outside dressed for the beach) but some of the benchmarks are humorous and/or completely useless. Benchmarks include:

===Temperature===
* {{w|Extremes on Earth|Earth's Hottest}}: 60⁠°C [140 °F]: The hottest temperature recorded on earth is actually {{W|List_of_weather_records#Heat|"only" 56.7}}. There have been reports of ten-twenty degrees higher (70-80⁠°C) but these measurments ae not verified or accepted as world records.
* Various heat waves: {{w|Dubai}} is a city in the United Arab Emirates, and is smack-dab in the middle of an equatorial desert, so their heat waves can get ''hot!''. The southern Unites States will typically be a few degrees hotter than the northern United States simply because it's closer to the equator, but as mentioned they're both above "Beach Weather".
*30°C [86 °F]: A little too hot so perfect for a trip to the beach.
*20°C [68 °F]: Is defined as room temperature in many experimental settings. For some this would feel a little cool. But 25°C [77°] would as mentioned be too warm for room temperature...
*10°C [50 °F]: Definitely wear a jacket. Especially if there is just a little breeze.
*0⁠°C [32 °F]: The freezing point of water (32°⁠F)
*-5 to -10°C: In Moscow -10°C is not really that cold - it can go "spit goes clink" cold in {{W|Moscow#Climate|Moscow}}, whereas -5°C [23 °F] in {{W|Boston#Climate|Boston}} may be very cold...
*-20°C: FuckFuckFuckCold and -30°C - Fuuuuuuuuuuuuck!: This is basically what some people would say when they step outside at this temperature. At -30°C, without taking wind chill into account, exposed skin will feel painful in under a minute and frostbite could begin in as little as ten minutes [http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=5FBF816A-1].
*-40⁠°C: Spit goes "clink": As shown in the drawing your spit would freeze ''before'' it hits the ground. This is the crossing point of the two temperature scales i.e. -40°C = -40 °F.

===Length===
*1 cm [.4 inch] : Width of microSD card and 3 cm - Length of SD card: Refers to the {{w|MicroSD card|memory cards}} used in cell phones, digital cameras, etc.
*12 cm [almost 5 inches]: CD rom are a common object so nice to know it is a dozen centimeters.
*14 cm [5 1/2 inches]: Most males would probably exaggerate the size of their penis, but 14–15 cm is very average.
*15 cm [almost 6 inches]: A Bic Pen
*80 cm [31 1/2 inches]: A typical doorway is also of standard size. This is barely over the minimum size typically required by codes for buildings [30 inches or 76.2 cm], but more than 50% over the size required for aircraft emergency exits. (It may seem illogical that larger doors are required in buildings than in airplanes, given airplanes are arguably more dangerous. However, there is no real disadvantage to using larger doors in buildings, which are not significantly pressurized, but using larger doors in aircraft would increase the force on the door caused by cabin pressure proportionally.)
*1 m [39.37 inches]: {{w|Lightsaber|Lightsaber Blade}}: Refers the weapon used in the {{w|Star Wars}} movie franchise. Canonically, the length of a Lightsaber's blade varies greatly depending on the setting of the weapon, but "one meter" is by no means a bad approximation.
*170 cm [5 feet, 7 inches]: {{w|Summer Glau}}: Refers to the height of the actress who portrays the character River Tam on the TV show {{w|Firefly (TV series)|Firefly}}.
*200 cm [6 feet, 6 and 3/4 inches]: Darth Vader: Refers to the height of the main antagonist from Star Wars.
*2.5 m [almost 10 feet]: Ceiling - of course very much depending on which type of building you are in!
*5 m [almost twenty feet]: Car Length - also very much depending on the car...
*16 m 4 cm: Human tower of Serenity crew: Again, this refers to the Firefly TV show, which takes place mostly on a space ship called Serenity.
**Presumably, if all the crew of Serenity were stacked on top of each other, this would be their combined height.
**The comic depicts four characters from the show standing on top of each other; the bottom figure is the crew's captain, {{w|Malcolm Reynolds}} in his signature coat. Judging from the other drawing of Summer Glau from the volume section, she is standing on top of the captain.
**The other five members of the crew should also be stacked on top of these four to reach the 16m height - giving them an average height of 1,82 cm (12 cm more than Summer Glaus height!)

===Speed===
:Here both the SI unit m/s as well as the more used unit kph is given.
*5 kph [3 mph] - 1.5 m/s: Walking at a normal pace
*13-25 kph [8-15 mph]: Jogging to sprinting.
*35 kph [21.75 mph] - 10 m/s: Fastest human: As of 2009, the fastest a human has been recorded to run in a single sprint is actually 45 kph, a record set by {{w|Usain Bolt}}.
*45-55 kph: Both cats and rabbits go much faster than normal people.
*75 kph [46.6 mph] - 20 m/s: Raptor: It's a comic written by Randal, of course a reference to the raptors from ''Jurassic Park'' was going to be here.
*100 kph - 25 m/s: A slow highway (62 MPH).
*110 kph [68.35 mph] - 30 m/s: Interstate (65 MPH): Refers to the {{w|Interstate|American highway system}}. (65 mph would actually be only 104.6 kph.)
*120 kph - 35 m/s: Speed you actually go when it says "65": People routinely break the aforementioned speed limit, and the police typically don't mind as long as it's not posing any danger. For the record, 120 kph is 74MPH.
*140 kph - 40 m/s: Raptor on Hoverboard: The Hoverboard is probably a reference to the ''Back to the Future'' series, though it's a fairly common trope in older science fiction stories.

===Volume===
*3 ml: The amount of blood in a fieldmouse.
*5 ml: A teaspoon - a very common measure.
*30 mL: Nasal Passages and 40mL - Shot Glass: The comic points out that you could just about fill a shot glass using the mucus from your nose. Since shot glasses are usually used for mixed drinks, the comic jokes that this mucus could constitute a new, disgusting drink - and this is depictured in the drawing.
*350 ml: Soda can (this is roughly correct for the cans used in the U.S., which hold 12 fluid ounces; in Europe, soda cans commonly hold 330ml or 500 ml).
*500 ml: Water bottle (this is the also the volume of a European water bottle).
*3 L: Two-liter bottle: Refers to a bottle which contains two liters (in the US usually soda). There is debate as to the reason for the discrepancy in volume.
*5 L: An adult male has about 5 L of blood in his body (An ''adequate'' vacuuming system could drain this blood out in 10 s - as per the title text!)
*30 L: Milk Crate: Refers to a {{w|Milk crate|type of small box}} originally used to transport milk but now often in demand to be used as bicycle basket, storage spaces, etc.
*55 L: Summer Glau: Again, this refers to the actress from Firefly.
*65 L: {{w|Dennis Kucinich}}: An American politician belonging to the {{w|Democratic Party (United States)|Democratic party}}, noted for his relatively strong (for the US) leftist views.
*75 L: {{w|Ron Paul}}: An American politician belonging to the rival {{w|Republican Party (United States)|Republican party}}, noted for his strong rightist views.
*200 L: Volume of refrigerator.
*As shown in the drawing of this part of the comic, the three persons mentioned above - Glau, Kucinich and Paul (summing up to 195 L) - could in principle all fit inside a standard refrigerator. Cueball thus attempts to push them all inside of one - and from the above mentioned political views it would be clear, the two men would not at all get along together trapped inside a fridge.

===Mass===
*3 g: {{w|M&M's|Peanut M&M}}: A small chocolate candy with a peanut inside
*100 g: Cell phone - this very much depends on the age of the cell phone, and the type etc.
*500 g [1 lb.]: A bottle of water contains 500 ml according to the volume section and thus have mass of 500 g.
*1–3 kg: Different types of laptops. The newest and the best is the lightest...
*5 kg [11 lb.]: {{w|Lcd monitor|LCD Monitor}}: A modern flat-screen-style monitor.
*15 kg: {{w|CRT monitor|CRT Monitor}}: An older-style, cathode ray tube-based monitor.
*4 kg: Cat and 4.1 kg - Cat (With Caption): Refers to the internet's love of putting {{w|Lolcat|captions on cats}}. Usually, this is done in a graphics program, but here the cat is actually physically carrying around his caption. The "with caption" part is most likely a reference to [[262: IN UR REALITY|Comic 262]], where [[Black Hat]] glues captions to cats, after running out of staples.
*60 kg [130 lb.]: Lady - for instance if she is Summer Glau - could be her again depicted in the comic - average weight of an adult woman.
*70 kg [150 lb.]: Dude - here depicted as Cueball who is the average guy, and 70 kg is average weight for an adult man.
*150 kg: Shaq: {{w|Shaq|Shaquille O'Neal}}, a famously tall basketball player.
*200 kg [440 lb.]: Your Mom
*220 kg: Your Mom (incl. 20 kg of cheap jewelry) and
*223 kg: Your Mom (also incl. 3 kg of Makeup)
*These last refers to a common type of {{w|Your mom}} joking insult whereby someone insults someone else's mother in a creative way. Here, the comic slyly calls your mom fat, then implies she wears way too much jewelry and finally also almost 7 pounds of makeup. This is a common theme in [[xkcd]].

==Title text==
The title text refers once again to Summer Glau's Firefly character, River, who (after being subjected to a long series of medical experiments) is severely mentally ill and often comes out with macabre — though scientifically accurate — pronouncements.

==Transcript==
:Guide to Converting to Metric
:The key to converting to metric is establishing new reference points. When you hear "26 degrees centigrade", instead of thinking "That's 79 degrees fahrenheit" you should think, "that's warmer then a house but cool for swimming." Here are some helpful tables of reference points:

:Temperature:
:60 degrees centigrade - Earth's Hottest
:45 degrees centigrade - Dubai Heat Wave
:40 degrees centigrade - Southern US Heat Wave
:35 degrees centigrade - Northern US Heat Wave
:30 degrees centigrade - Beach weather
:25 degrees centigrade - Warm Room
:20 degrees centigrade - Room Temperature
:10 degrees centigrade - Jacket Weather
:0 degrees centigrade - Snow!
:-5 degrees centigrade - Cold Day (Boston)
:-10 degrees centigrade - Cold Day (Moscow)
:-20 degrees centigrade - FuckFuckFuckCold
:-30 degrees centigrade - Fuuuuuuuuuuck!
:-40 degrees centigrade - Spit goes "clink"
:[Stick figure next to last three lines.]
:Man: ''Pthoo'' [Man spits.]
:Spit: ''Clink!'' [Spit bounces off ground.]

:Length
:1cm - Width of microSD card
:3cm - Length of SD card
:12cm - CD Diameter
:14cm - Penis
:15cm - BIC pen
:80cm - Doorway width
:1m - Lightsaber Blade
:170cm - Summer Glau
:200cm - Darth Vader
:2.5m - Ceiling
:5m - Car-length
:16m4cm - Human tower of Serenity crew
:[Human tower of Serenity crew stick figures depicted taking up from second line of panel to bottom.]

:Speed
:5 kph - 1.5 m/s - Walking
:13 kph - 3.5 m/s - Jogging
:25 kph - 7 m/s - Sprinting
:35 kph - 10 m/s - Fastest Human
:45 kph - 13 m/s - Housecat
:55 kph - 15 m/s - Rabbit
:75 kph - 20 m/s - Raptor
:100 kph - 25 m/s - Slow Highway
:110 kph - 30 m/s - Interstate (65 MPH)
:120 kph - 35 m/s - Speed you actually go when it says "65"
:140 kph - 40 m/s - Raptor on Hoverboard

:Volume
:3mL - Blood in a fieldmouse
:5mL - Teaspoon
:30mL - Nasal Passages
:40mL - Shot Glass
:So when it's blocked, the mucus in your nose could about fill a shot glass.
:[Image of a shot glass.] Related: I've invented the worst mixed drink ever.
:350mL - Soda Can
:500mL - Water Bottle
:3L - Two-Liter Bottle
:5L - Blood in a Human Male
:30L - Milk Crate
:55L - Summer Glau
:65L - Dennis Kucinich
:75L - Ron Paul
:200L - Fridge
:[Cueball shoving Ron Paul, Summer Glau, and Dennis Kucinich into fridge.]
:[Above fridge, circled, is 55+65+75<200]

:Mass
:3g - Peanut M&M
:100g - Cell Phone
:500g - Bottled Water
:1kg - Ultraportable Laptop
:2kg - Light-Medium Laptop
:3kg - Heavy Laptop
:5kg - LCD Monitor
:15kg - CRT Monitor
:4kg - Cat [Drawing of cat.]
:4.1kg - Cat (With Caption) [Drawing of cat, going "Mrowl?", and holding a caption.]
:60kg - Lady
:70kg - Dude
:150kg - Shaq
:[Stick figure of Megan and Cueball beside previous 3 lines.]
:200kg - Your Mom
:220kg - Your Mom (incl. cheap jewelry)
:223kg - Your Mom (also incl. Makeup)

{{comic discussion}}
[[Category:Charts]]
[[Category:Comics featuring real people]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Velociraptors]]
[[Category:Your Mom]]
[[Category:Firefly]]

720: Recipes

2014-09-29T00:36:52Z

173.245.54.213: /* Explanation */

{{comic
| number = 720
| date = March 29, 2010
| title = Recipes
| image = recipes.png
| titletext = To be fair, the braised and confused newt on a bed of crushed Doritos turned out to be delicious.
}}

==Explanation==
A {{w|genetic algorithm}} starts with a set of candidates and evaluates them. The best candidates are combined and randomly mutated to form the candidates for the next generation. After being allowed to proceed for an extended period, a genetic algorithm can often produce remarkable results. If the initial candidates are randomly-generated (as appears to be the case here), the initial generations are usually horrible.

In the comic, the computer science department is the host of a dinner party based on recipes produces by a genetic algorithm. Based on the remarks of the second diner, this is probably not the first generation, and the results are still horrible. The host of the party is so enamored of the promise of the genetic algorithm that he fails to take into account that it will be several years before the recipes become remotely good.

The title text could make reference to the fact that genetic algorithms will sometimes return results which are highly abnormal and vastly deviate from what we would think to be "selected for," but nonetheless can be quite successful, albeit unorthodox.

==Transcript==
:[Three people, one woman and two men, sit along a table with dishes and drinks in front of them. A fourth man is walking in, a plate with food on it in one hand, a laptop in the other.]

:Woman: I've got... Cheerios with a shot of vermouth.
:Man #1: At least it's better than the quail eggs in whipped cream and MSG from last time.
:Man #2: Are these Skittles ''deep-fried''?

:Cueball: C'mon guys, be patient. In a few hundred more meals, the genetic algorithm should catch up to existing recipes and start to optimize.
:We've decided to drop the CS department from our weekly dinner party hosting rotation.

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