explain xkcd - User contributions [en]

2781: The Six Platonic Solids

2023-05-27T07:52:11Z

Qha: Fix typo

{{comic
| number = 2781
| date = May 26, 2023
| title = The Six Platonic Solids
| image = the_six_platonic_solids_2x.png
| imagesize = 368x370px
| noexpand = true
| titletext = Plato made the solids, and five were gifted to the mathematicians. But in secret Plato forged a sixth solid to rule over all the others.
}}

==Explanation==
{{incomplete|Created by a JORB WELL DONE - Why call it Jorb? Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic imagines an alternate reality where mathematicians discover a new {{w|Platonic solid}}. There are five Platonic solids, and it has been [https://sites.math.washington.edu/~julia/teaching/445_Spring2013/Paper_Euler.pdf mathematically proven] that there are exactly five in three-dimensional space. However, in 4 dimensions there exist 6 regular polytopes, 5 which are analogous to the 5 in 3d space, and a sixth which is analogous to the Rhombic dodecahedron. In the comic, Randall proposes a new Platonic solid, called the jorb, which appears to be a roughly conical shape with a round base, a triangular tip, and a rectangular extension at the bottom. Its surface also seems to have parallel grooves or ribs. The jorb does not fit the criteria for a Platonic solid, since a Platonic solid's faces have to be regular polygons and also all have to be the same shape. Furthermore, each vertex of the solid must be formed out of the same number of faces as the other vertices.

The title text references {{w|Lord of The Rings}}, in which the One Ring was forged in secret to rule the three given to the elves, the 7 given to the dwarfs and and the nine given to the humans. Sauron could in principle control these other 19 rings with his master ring, the One Ring to rule them all. The joke is that Plato forged a sixth platonic solid (the Jorb) to rule the five he gave to the mathematicians, just like Sauron ruled the three species from Middle Earth with his one ring.

==Transcript==
:[Six geometrical shapes are shown. All have gray surface areas with different shading to reflect their orientation. There is one shape in the middle with the other five arranged around it roughly in a pentagon. With two at the top, two just below the central and one directly below the central shape. Each shape has a label. The five above the bottom one are names after the platonic solids, and are drawn to look like them. The last one at the bottom has a roughly conical shape with a round base, a triangular tip, and a rectangular extension at the bottom. It surface also seems to have parallel grooves or ribs. Here the labels in reading order with the four rows mentioned above used.]
:Cube
:Dodecahedron
:Icosahedron
:Octahedron
:Tetrahedron
:Jorb

:[Caption below the comic:]
:Mathematicians long believed there were only five platonic solids, all regular polyhedra, until this year's discovery of the Jorb.

{{comic discussion}}

[[Category:Geometry]]
[[Category:Math]]
[[Category:LOTR]]
[[Category:Comics featuring real people]]

2367: Masks

2020-10-02T20:51:38Z

Qha: /* Explanation */ syntax

{{comic
| number = 2367
| date = October 2, 2020
| title = Masks
| image = masks.png
| titletext = Haunted Halloween masks from a mysterious costume shop that turn you evil and grow into your skin score a surprisingly high 80% filtration efficiency in R. L. Stine-sponsored NIOSH tests.
}}

==Explanation==
{{incomplete|Created by a BATMAN WEARING A N95 MASK. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

This comic is a line from top to bottom explaining how good different types of masks are at preventing respiratory virus transmission. As with many comics in 2020, it was made with Coronavirus strain 2019 (COVID-19) in mind, a virus that primarily transmits through air droplets expelled from the human nose and mouth.

*'''Lone Ranger''' and '''Zorro''': A strip of cloth around the eye-level. Does not cover the mouth and nose, the main ways the virus enters the body.
*'''{{w|Batman}}''': Batman's iconic headgear has gone through many revisions, and consists either of a simple cloth cowl or a helmet and visor. Does not cover the mouth, but may cover the nose.
*'''Theater masks''': A pair of {{w|Sock and buskin}} masks, traditionally used as a symbol of performance theater since ancient Greece. The eye and mouth holes are often open, thus exposing the wearer.
*'''Skincare''': A layer of mud or moisturizer. By nature, it does not cover the mouth or nostrils, but it may keep the wearer from touching their face and is usually worn by someone sitting in a chair or lying back on a bed, not out getting in other people's personal space.
*'''Scarecrow''': A burlap sack. While it provides some cover to the mouth and nose, it is heavily porous.
*'''Guy Fawkes''': A plastic mask. Most Guy Fawkes masks provide small holes in the front for comfort, thus facilitating spread of the virus.
*'''Cloth''': A cloth mask that blocks most large particles, like virus-laden saliva. To be most effective, it must cover nose as well as the mouth. These are much cheaper than N95 masks, and can be reused by washing. Not all cloth masks are created equal, some designs and materials are more effective than others at holding back contagious particles, but Randall lists them under "Effective" on the whole.
*'''{{w|Spiderman}}''': A full face covering of spandex-like material. Would block most virus particles.
*'''{{w|N95 mask}}''': A surgical mask. The name "N95" signals that it is not resistant to oil, but successfully filters 95% of airborne particles. It has proven to be one of the more successful masks during the 2020 pandemic.
*'''{{w|Scuba_Diving|SCUBA}}''': A '''S'''elf-'''C'''ontained '''U'''nderwater '''B'''reathing '''A'''pparatus. Most SCUBA equipment used an open-circuit design allowing exhaled air to vent to the atmosphere. Underwater, this would not be a threat to other divers who would also be breathing air from their tanks. However, on land a typical SCUBA regulator would expose others to virus particles. Closed-circuit SCUBA apparatus recirculate the user’s gas supply but they still contain a means of venting extra gas into the atmosphere. Neither system contains expiratory HEPA filters making both ineffective at preventing virus transmission. That all said, SCUBA equipment still covers the face and nose, rather than directly exposing others to unshielded breathing and coughing.
*'''Vader''': A suit of armor with a built-in rebreather. Similar to SCUBA gear, circulates air back to the user, preventing spread of the virus to anyone else.
*'''Mysterio''': A glass helmet. In the comics Mysterio often uses mind-altering chemicals, and his suit is designed to shield himself from his own weapons. By the same design, it would shield himself and others from the spread of viral infection.
*'''Haunted Halloween Masks''': A reference to {{w|The Haunted Mask}} by {{w|R. L. Stine}}. The mask transforms the wearer into a monster, with an open (uncovered) nose and mouth, but apparently R. L. Stine had them tested and found that the wearer is still somehow substantially protected against infection (in spite of the other negative side effects of being cursed).

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

[Title at top]
:'''Masks'''
:By effectiveness at preventing respiratory virus transmission

[Vertical Line going top to bottom. At the top: Not effective. In the middle: Effective. On the bottom. Extremely Effective. From top to bottom:]

:[Approx. 2%]Zorro/Lone Ranger
:[Approx. 3%]Batman
:[Approx. 7%]Theater
:[Approx. 10%]Skincare
:[Approx. 15%]Scarecrow
:[Approx. 18%]Guy Fawkes
:[Approx. 48%]Cloth
:[Approx. 52%]Spiderman
:[Approx. 68%]N95
:[Approx. 71%]Scuba
:[Approx. 80%]Vader
:[Approx. 90%]Mysterio



{{comic discussion}}

2367: Masks

2020-10-02T20:46:58Z

Qha: /* Transcript */ Typo

{{comic
| number = 2367
| date = October 2, 2020
| title = Masks
| image = masks.png
| titletext = Haunted Halloween masks from a mysterious costume shop that turn you evil and grow into your skin score a surprisingly high 80% filtration efficiency in R. L. Stine-sponsored NIOSH tests.
}}

==Explanation==
{{incomplete|Created by a BATMAN WEARING A N95 MASK. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

This comic is a line from top to bottom explaining how good different types of masks are at preventing respiratory virus transmission. As with many comics in 2020, it was made with Coronavirus strain 2019 (COVID-19) in mind, a virus that primarily transmits through air droplets expelled from the human nose and mouth.

*'''Lone Ranger''' and '''Zorro''': A strip of cloth around the eye-level. Does not cover the mouth and nose, the main ways the virus enters the body.
*'''{{w|Batman}}''': Batman's iconic headgear has gone through many revisions, and consists either of a simple cloth cowl or a helmet and visor. Does not cover the mouth, but may cover the nose.
*'''Theater masks''': A pair of {{w|Sock and buskin}} masks, traditionally used as a symbol of performance theater since ancient Greece. The eye and mouth holes are often open, thus exposing the wearer.
*'''Skincare''': A layer of mud or moisturizer. By nature, it does not cover the mouth or nostrils, but it may keep the wearer from touching their face and is usually worn by someone sitting in a chair or lying back on a bed, not out getting in other people's personal space.
*'''Scarecrow''': A burlap sack. While it provides some cover to the mouth and nose, it is heavily porous.
*'''Guy Fawkes''': A plastic mask. Most Guy Fawkes masks provide small holes in the front for comfort, thus facilitating spread of the virus.
*'''Cloth''': A cloth mask that blocks most large particles, like virus-laden saliva. To be most effective, it must cover nose as well as the mouth. These are much cheaper than N95 masks, and can be reused by washing. Not all cloth masks are created equal, some designs and materials are more effective than others at holding back contagious particles, but Randall lists them under "Effective" on the whole.
*'''{{w|Spiderman}}''': A full face covering of spandex-like material. Would block most virus particles.
*'''{{w|N95 mask}}''': A surgical mask. The name "N95" signals that it is not resistant to oil, but successfully filters 95% of airborne particles. It has proven to be one of the more successful masks during the 2020 pandemic.
*'''{{w|Scuba_Diving|SCUBA}}''': A '''S'''elf-'''C'''ontained '''U'''nderwater '''B'''reathing '''A'''pparatus. Most SCUBA equipment used an open-circuit design allowing exhaled air to vent to the atmosphere. Underwater, this would not be a threat to other divers who would also be breathing air from their tanks. However, on land this a typical SCUBA regulator would expose others to virus particles. Closed-circuit SCUBA apparatus recirculate the user’s gas supply but they still contain a means of venting extra gas into the atmosphere. Neither system contains expiratory HEPA filters making both ineffective at preventing virus transmission. That all said, SCUBA equipment still covers the face and nose, rather than directly exposing others to unshielded breathing and coughing.
*'''Vader''': A suit of armor with a built-in rebreather. Similar to SCUBA gear, circulates air back to the user, preventing spread of the virus to anyone else.
*'''Mysterio''': A glass helmet. In the comics Mysterio often uses mind-altering chemicals, and his suit is designed to shield himself from his own weapons. By the same design, it would shield himself and others from the spread of viral infection.
*'''Haunted Halloween Masks''': A reference to {{w|The Haunted Mask}} by {{w|R. L. Stine}}. The mask transforms the wearer into a monster, with an open (uncovered) nose and mouth, but apparently R. L. Stine had them tested and found that the wearer is still somehow substantially protected against infection (in spite of the other negative side effects of being cursed).

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

[Title at top]
:'''Masks'''
:By effectiveness at preventing respiratory virus transmission

[Vertical Line going top to bottom. At the top: Not effective. In the middle: Effective. On the bottom. Extremely Effective. From top to bottom:]

:[Approx. 2%]Zorro/Lone Ranger
:[Approx. 3%]Batman
:[Approx. 7%]Theater
:[Approx. 10%]Skincare
:[Approx. 15%]Scarecrow
:[Approx. 18%]Guy Fawkes
:[Approx. 48%]Cloth
:[Approx. 52%]Spiderman
:[Approx. 68%]N95
:[Approx. 71%]Scuba
:[Approx. 80%]Vader
:[Approx. 90%]Mysterio



{{comic discussion}}

2367: Masks

2020-10-02T20:43:11Z

Qha: /* Explanation */

{{comic
| number = 2367
| date = October 2, 2020
| title = Masks
| image = masks.png
| titletext = Haunted Halloween masks from a mysterious costume shop that turn you evil and grow into your skin score a surprisingly high 80% filtration efficiency in R. L. Stine-sponsored NIOSH tests.
}}

==Explanation==
{{incomplete|Created by a BATMAN WEARING A N95 MASK. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

This comic is a line from top to bottom explaining how good different types of masks are at preventing respiratory virus transmission. As with many comics in 2020, it was made with Coronavirus strain 2019 (COVID-19) in mind, a virus that primarily transmits through air droplets expelled from the human nose and mouth.

*'''Lone Ranger''' and '''Zorro''': A strip of cloth around the eye-level. Does not cover the mouth and nose, the main ways the virus enters the body.
*'''{{w|Batman}}''': A helmet and visor. Does not cover the mouth, but may cover the nose.
*'''Theater masks''': A pair of {{w|Sock and buskin}} masks, traditionally used as a symbol of performance theater since ancient Greece. The eye and mouth holes are often open, thus exposing the wearer.
*'''Skincare''': A layer of mud or moisturizer. By nature, it does not cover the mouth or nostrils, but it may keep the wearer from touching their face and is usually worn by someone sitting in a chair or lying back on a bed, not out getting in other people's personal space.
*'''Scarecrow''': A burlap sack. While it provides some cover to the mouth and nose, it is heavily porous.
*'''Guy Fawkes''': A plastic mask. Most Guy Fawkes masks provide small holes in the front for comfort, thus facilitating spread of the virus.
*'''Cloth''': A cloth mask that blocks most large particles, like virus-laden saliva. To be most effective, it must cover nose as well as the mouth. These are much cheaper than N95 masks, and can be reused by washing.
*'''{{w|Spiderman}}''': A full face covering of spandex-like material. Would block most virus particles.
*'''{{w|N95 mask}}''': A surgical mask. The name "N95" signals that it is not resistant to oil, but successfully filters 95% of airborne particles. It has proven to be one of the more successful masks during the 2020 pandemic.
*'''{{w|Scuba_Diving|SCUBA}}''': A '''S'''elf-'''C'''ontained '''U'''nderwater '''B'''reathing '''A'''pparatus. Most SCUBA equipment used an open-circuit design allowing exhaled air to vent to the atmosphere. Underwater, this would not be a threat to other divers who would also be breathing air from their tanks. However, on land this a typical SCUBA regulator would expose others to virus particles. Closed-circuit SCUBA apparatus recirculate the user’s gas supply but they still contain a means of venting extra gas into the atmosphere. Neither system contains expiratory HEPA filters making both ineffective at preventing virus transmission.
*'''Vader''': A suit of armor with a built-in rebreather. Similar to SCUBA gear, circulates air back to the user, preventing spread of the virus to anyone else.
*'''Mysterio''': A glass helmet. In the comics Mysterio often uses mind-altering chemicals, and his suit is designed to shield himself from his own weapons. By the same design, it would shield himself and others from the spread of viral infection.
*'''Haunted Halloween Masks''': A reference to {{w|The Haunted Mask}} by {{w|R. L. Stine}}. The mask transforms the wearer into a monster, with an open (uncovered) nose and mouth, but apparently R. L. Stine had them tested and found that the wearer is still somehow substantially protected against infection (in spite of the other negative side effects of being cursed).

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

[Title at top]
:'''Masks'''
:By effectiveness at preventing respiratory virus transmission

[Vertical Line going top to bottom. At the top: Not effective. In the middle: Effective. On the bottom. Extremely Effective. From top to bottom:]

:[Approx. 2%]Zorro/Lone Ranger
:[Approx. 3%]Batman
:[Approx. 7%]Theater
:[Approx. 10%]Skincare
:[Approx. 15%]Scarecrow
:[Approx. 18%]Guy Fawkes
:[Approx. 48%]Cloth
:[Approx. 52&]Spiderman
:[Approx. 68%]N95
:[Approx. 71%]Scuba
:[Approx. 80%]Vader
:[Approx. 90%]Mysterio



{{comic discussion}}

1264: Slideshow

2013-09-15T19:07:13Z

Qha: Spelling

{{comic
| number = 1264
| date = September 13, 2013
| title = Slideshow
| image = slideshow.gif
| titletext = Points to anyone who hacks the Flickr devs' computers to make their text editors do this when you click on anything.
}}

==Explanation==
{{incomplete}}
It is very common for websites to feature a gallery of images – a website for a school, for example, might feature pictures of the students and teachers. Some websites display images in the form of a slideshow like this comic, with slow zoom and pan effects and fades between the images. This effect has been dubbed the {{w|Ken Burns effect}} after documentary filmmaker {{w|Ken Burns}} who popularized the effect. In many cases, the slideshow is a fixed element, and can't be controlled by the user. This prevents the user from navigating through the images at their own pace or viewing any one image for an extended period, and can be distracting. Randall, through [[Cueball]], expresses frustration at this.

The title text suggests points will be awarded to whoever can add that annoying effect to the text editors of the developers of {{w|Flickr}} (a photo-hosting website), so they can be subjected to the same thing to which they are subjecting Cueball. This may be a response to recent changes to Flickr's website that includes such slideshows as one option; that said, Flickr has always allowed (and seems to continue to allow) users to browse galleries in a normal grid layout and with user-controlled photo-by-photo full-window layout.

==Transcript==

:Dear website operators,
:[Animation of Cueball saying these three things with fading and zooming effects.]
:Cueball: I will ''never''...
:Cueball: ...want to browse a series of images...
:Cueball: ...like this.

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

1196: Subways

2013-04-08T17:38:32Z

Qha: /* Explanation */ reduce redundancy

{{comic
| number = 1196
| date = April 8, 2013
| title = Subways
| image = subways.png
| titletext = About one in three North American subway stops are in NYC.
}}

The xkcd page links to [http://xkcd.com/1196/large/ a much larger version], which has another text added:
<blockquote style="font-style:italic">
For the pedantic rail enthusiasts, the definition of a subway used here is, with some caveats, "a network containing high capacity grade-separated passenger rail transit lines which run frequently, serve an urban core, and are underground or elevated for at least part of their downtown route." For the rest of you, the definition is "a bunch of trains under a city."
</blockquote>

==Explanation==
The comic shows the maps of all North American {{w|subway}} networks. In reality, none of these systems are interconnected, but in the diagram subways from different cities that have the same color on the official subway map are whimsically connected (for example, the "Ohio-California Tunnel" connecting the Green Lines of Cleveland and Los Angeles). The "Springfield Monorail" is fictional, from the animated series "{{w|The Simpsons}}" (see {{w|Marge vs. the Monorail}}), but its approximate location on this map would suggest the [http://www.seattlemonorail.com/ Seattle Monorail]. And the San Francisco line to Sunnydale is the setting for {{w|Buffy the Vampire Slayer (TV series)}}.

The networks on the map are displayed in (relatively) geographic position, with {{w|Vancouver}} being the most North-West, and {{w|Mexico City}} being the most South – East/West and North/South order are correct, but distances are not (in reality, Vancouver is closer to Chicago than to Toronto for example).

The "Graveyard for passengers killed by closing doors" refers to the warning played in the Washington DC Metro system advising passengers that the subway doors are "not like elevator doors" and will close on your limbs or belongings rather than opening when contact with an object is detected.

Here are some official subway maps:
* Boston - http://www.mbta.com/schedules_and_maps/subway/
* Chicago - http://www.transitchicago.com/assets/1/maps/P19_2012_CTA_Rail_Map.pdf
* Cleveland - http://www.riderta.com/pdf/maps/System_Map_Rapid_Connect.pdf
* Montreal - http://www.stm.info/english/metro/images/plan-metro.jpg
* New York City - http://www.mta.info/maps/submap.html
* Toronto - http://tourbytransit.com/toronto/images/Toronto-Subway-Map.png
* Vancouver - http://mapa-metro.com/mapas/Vancouver/mapa-metro-vancouver.png
* San Francisco - http://www.bart.gov/images/global/system-map.gif
* Mexico city - http://www.metro.df.gob.mx/imagenes/red/redinternet.pdf

==Transcript==
:

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Charts]]
[[Category:Large drawings]]