explain xkcd - User contributions [en]

3242: Aperiodic Table

2026-05-06T23:57:20Z

LandmineFlipFlop:

{{comic
| number = 3242
| date = May 6, 2026
| title = Aperiodic Table
| image = aperiodic_table_2x.png
| imagesize = 740x464px
| noexpand = true
| titletext = Scientists occasionally invent alternative periodic table layouts, which is usually a sign that they don't have enough enrichment in their enclosures.
}}

==Explanation==
{{incomplete|This page was created APERIODICALLY. Don't remove this notice too soon.}}
The {{w|Periodic Table of the Elements}} is a diagram often used to show the properties of the elements that make up the world. Its structure represents several properties of the elements- for example, all elements in a single column will have similar chemical properties, and the elements increase in size when reading it left-to-right and top-to-bottom (like a book).

Randall spoofs this concept by creating a similar, but useless, diagram. The original table is "periodic" because it has consistent, repeating patterns that are represented by the horizontal position of the elements. Randall's table is "aperiodic", meaning it has no consistent, repeating patterns. Instead, it is just a line in order by {{w|atomic number}}. To fit in the same space as a normal periodic table, the sequence snakes back and forth and down the page in a space-filling manner. The diagram is not actually helpful, since it contains next-to-no information other than the atomic number of each element, plus faint colouring on each box to show its category, though due to the dull colours that is also quite inconvenient to use, and it depicts this information in an unnecessarily unhelpful and hard-to-read format.

Chemistry and the periodic table is a periodic theme on xkcd, with there being many comics featuring humorous variations and "fixes" of it, such as [[2639: Periodic Table Changes]] and [[2975: Classical Periodic Table]].

The title text might be a reference to [[3052: Archive Request]], or maybe some real attempts at inventing actual 'non-grid' linear versions of the periodic table, such as the {{w|File:Elementspiral_(polyatomic).svg|'periodic snail'}} that was created by {{w|Otto Theodor Benfey}}. It is also likely joking by relating scientist to household pets, from the reference to not having enough enrichment in their enclosures.

Thallium’s symbol is incorrectly given as Ti in this comic; its actual symbol is Tl.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

The Aperiodic Table of the Elements

[Rectangles showing the atomic symbols and atomic numbers from H 1 through Og 118 are arranged in a serpentine chain. The color of each rectangle matches the the pattern of a standard periodic table. For example, the noble elements all have a red background.]

{{comic discussion}}<noinclude>

3227: Creation

2026-04-23T15:04:55Z

LandmineFlipFlop: a line to make it more clear where the april fools settings were and are available

{{comic
| number = 3227
| date = April 1, 2026
| title = Creation
| image = creation_2x.png
| imagesize = 567x198px
| noexpand = true
| titletext = This xkcd.com update introduces a variety of new reading modes which can be activated through the menu.
}}
{{series
| series = April
| number = 18
| date = April 1, 2026
| days_late =
| day_category = Wednesday
| prev_title = 3074: Push Notifications
| prev_date = April 9, 2025
| next_title =
| next_date =
}}
To experience the interactivity of the web page, visit the {{xkcd|3227|original comic}}!

==Explanation==
In this {{w|April Fool's Day}} comic, several new viewing modes have been added to the xkcd website, accessible through a {{w|drop-down list}} beneath the comic (not visible on Explain xkcd). This was the first time in 15 years that the xkcd site itself had been redesigned, with the previous site redesign coming in 2011 with [[880: Headache]]. This allows various different viewing experiences for the entire website (this included other comics until 15 April 2026; since then it only works on this comic). Some are "normal" viewing modes, like the typical "light" and "dark" modes, but others take such things further and/or in more esoteric ways. This includes an "airplane mode" (see below) that parodies and subverts the {{w|Airplane mode|normal implementation}}.

The accompanying comic references one of the first lines of the {{w|Bible}} (Genesis 1:3), wherein God creates light. Here, though, before God has a chance to fully appreciate their work, a person on Earth immediately requests an implementation of {{w|dark mode}}. Dark mode is a feature on many websites and devices which displays text in white against a black background instead of the default black text on a white background. In low ambient light this makes for a less intense viewing experience that is easier on the eyes, so many people who spend a lot of time looking at screens prefer dark mode (whereas casual users often find light mode easier to read). On OLED screens, another benefit is that less battery life is consumed because of the primarily low brightness of the screen, which makes it useful for those who want to be energy-efficient or extend their battery life.

This demand represents a common experience for web and app designers, who spend a lot of time creating something that looks beautiful to them, and in their particular use case, only to find when it is put out into the wild that it doesn't suit the needs of many of their actual users, who don't particularly care about the effort they've put in.

Dark mode is not usually implemented on planets,{{cn}} although one could argue that night-time is effectively Earth's "dark mode", which could have been created by God as a response to the person. (That seems likely, in fact, given that the very next words in Genesis 1:4 are "and he separated the light from the darkness".) The comic deviates somewhat from traditional Judeo-Christian theology, as in Genesis the day/night cycle was created on the first day, but humans were created on the sixth day - thus, the "dark mode" (night-time) would already have been implemented by the time humans existed. Possibly the person is actually requesting a dark mode that can be toggled at will, rather than one which occurs automatically each day.

Unlike most comics, the title text contains no jokes, but rather explains the update and gives basic instructions.

The comic credits the "Excellent Design Team", consisting of Amber, Benjamin Staffin, and Kevin who helped create the modes.

This credit was also implemented as the new [[Header text]], so that the explanation for the new mode would be visible when viewing all other comics on xkcd, as well as the credit to the design team, see more details [[Header_text#2026-04-07_-_Reading_Modes|here]].

When the comic first released the veiwing modes were available on every comic, but currently the settings are only available on the original comic.

===List of Modes===
; Light Mode
: The usual site experience. Typically, where sites have light and dark modes, light is the default option, so as to mimic ink on paper (such as printed {{w|newspaper comic strip}}s).

; Lighter Mode
: The entire web page is filtered to look {{w|Exposure (photography)#Overexposure and underexposure|overexposed}}, making colors wash out and reducing the contrast.

; Dark Mode
: A standard "white content on black background" dark mode. Specifically, Dark Mode inverts the colors of the page (which makes a {{w|Negative (photography)|colour-negative}} and then hue-rotates it by 180 degrees (to make hue return to normal, only brightness-reversed. (For example, see comic [[556: Alternative Energy Revolution|556]], with dark mode enabled, to see how the hue is maintained.) The background of the page, normally light blue, becomes a dark blue; (near-)whites become (near-)blacks, and vice-versa, only mid-tones staying the same. This inversion makes the content of this particular comic, with the original transition from a dark pane to "let there be light" panes and the subsequent request for this very feature, particularly nonsensical, as it seems to start fully bright, then darken as God creates light.

; Darkest Mode
: Everything on the webpage turns completely black (severely 'underexposed', in effect, the opposite to "Lighter mode" but also even more extreme). The exception is the drop-down menu widget, which may appear as merely a dark gray — and depending upon the browser itself, the dropped-down menu may be its 'natural' appearance when it becomes fully active — which is of course extremely helpful for navigating back out of this mode or onward onto others.

; Blurry Mode
: {{w|Blur (photographic effect)|Blurs}} the entire webpage. This is not conventionally desirable as it makes it harder to read text and interpret visuals. Whereas light and dark mode support can improve {{w|Web accessibility|accessibility}} for certain vision conditions, this mode makes already poor vision even worse.

; Grayscale Mode
: Applies a standard {{w|grayscale}}/{{w|Colorfulness#Saturation|desaturation}} conversion filter to the entire webpage. Many devices provide a grayscale mode as one of their color filter settings, which can simulate different {{w|color vision deficiencies}}. Grayscale specifically can also help improve focus by preventing colors from catching the eye and making distractions less visually appealing.

; Greyscale Mode
: Operates identically to Grayscale Mode, but also changes the spelling of "math" in the slogan at the top of the page to "maths" (to go along with the respective {{w|American and British English spelling differences|British English}} use of ''{{wiktionary|gray}}/{{wiktionary|grey}}'').

; Dorian Greyscale Mode
: Makes the webpage slowly turn grey, including darkening/fading-to-grey 'white' areas. This refers to ''{{w|The Picture of Dorian Gray}}'', in which the titular character has a portrait that slowly ages and fades out while the character stays young and handsome. The transformation finishes after 5 minutes.

: Of note is that the surname of the titular character is "{{w|Grey (disambiguation)#People|Gray}}" (as is still common, if not dominant, in Britain), but the mode itself is named for the primary British/non-American standard English version of the word for such a hueless shade.

: No relation to the {{w|Dorian mode}}, a musical scale.

; Space Opera Mode
: Turns the entire page into a ''{{w|Star Wars}}''-style opening scroll, which loops round until you change the mode. Scrolling the mouse scrolls up or down through the page content. {{w|Space opera}} is a genre of sci-fi that ''Star Wars'' falls under. Opera is the name of a web browser, though it does not usually display content in this way.

; 3D Mode
: Makes the comic render in {{w|Anaglyph 3D|anaglyphic stereoscopy}}. [[Randall]] has used 3D space before for [[848|another joke comic]]. He has also utilized a similar joke for the 2011 xkcd redesign, which was released along with [[880: Headache]].

; Origami Mode
: Rotates and folds various pieces of the webpage, as if it were {{w|origami}}-folded.

; Ink Mode
: Recolors the webpage as if drawn in blue ink, which is often used for the initial roughing-out of a drawing.

; Spring Mode
: Gives the comic a simple physics simulation, making it slightly rotate around an axis when the page is scrolled, and giving it a {{w|springboard}} look, hence the name. The axis around which the page precesses is perpendicular to the axis the user scrolls on. This means that when the page is scrolled vertically (the usual direction), the comic wobbles around a horizontal axis, but when scrolled horizontally (if your screen size or zoom allows it), the comic precesses about the vertical axis.

; Antipodes Mode
: Turns the entire webpage upside down. An {{w|antipodes|antipode}} is the point on the Earth's surface directly opposite of another, but "The Antipodes" is also a term used to refer to {{w|Australia}} and {{w|New Zealand}} by inhabitants of the northern hemisphere. Note: When the comic was first published this was labeled "Southern Hemisphere Mode".

; Hacker Mode
: Recolors the entire webpage in the stereotypical green-on-black coding environment color scheme often used by {{w|hacker}}s in film and TV. This visual shorthand is a holdover from early {{w|monochrome monitor}}s that used P1 phosphor. (Modern terminal software has no such limitations, and many programmers today use {{w|syntax highlighting}} to color-code operators and keywords.)

; Screensaver Mode
: Makes the comic float around on the webpage, bouncing as it hits the edges. A common type of {{w|screensaver}} has some text or other element drifting around the screen in this way. Many people ended up watching such screensavers, waiting for the bouncing graphic to hit the corner of the screen. Like with Hacker Mode, there is an element of nostalgia to this; screensavers are less necessary on modern LCD screens, so fewer setups use them.

; Modem Mode
: Slowly reveals the comic from top to bottom, as if slowly loading (but [[598: Porn|only in approximation]]) the way images often used to have to be progressively rendered from a low-rate stream of image data in the days of more limited dial-up connections and also a lower-performance {{w|internet backbone}} in general. This is accompanied by audio of the sound of a {{w|modem}} communicating over such a connection. NB - this mode does not appear to function correctly/reliably for some viewers.

; Stained Glass Mode
: Fills each closed area of the comic with a separate color to mimic the look of {{w|stained glass}} imagery. The colors vary each time this mode is selected or the page is reloaded in this mode, which works by flooding a single pseudorandom hue over all areas of near-white, each flood bounded only by any sufficiently dark or saturated drawn line/border. Strangely enough, on this mode you can't see the title text. This is because the canvas used to apply the hues is functionally covering the image: the javascript used to do this should have been made to copy the comic image's title attribute and make it apply to the overlaid canvas for the benefit of the browser.

; Airplane Mode
: Makes the comic fly around on the page, with the {{w|onomatopoeia}} "NYOOM!" written next to it, as if it were an {{w|airplane}}. This is unlike the usual use of {{w|airplane mode}} to refer to disabling the cellphone (or all {{w|radio frequency}}) features of a mobile device, as required on most flights. Of course, the website's "Airplane Mode" does no such thing, and would be pointless to enable on an airplane.{{cn}}

; Boat Mode
: Makes the entire webpage tilt back and forth, emulating the way a boat rolls on the water. While [[165: Turn Signals|extremely unlikely]], this could theoretically counteract the rocking motion of a boat, stabilizing the page content. In practice, it is unlikely to help with {{w|seasickness}}. (As of 2024, some smart devices started offering a "vehicle motion cues" feature that is meant to reduce motion sickness, although it is designed for road vehicles rather than watercraft.)

: This mode is a reference to the longstanding mention of a Boat Mode in the [[footnote]], which says "Remove your device from Airplane Mode and set it to Boat Mode".

==Transcript==
:[Black background with white caption boxes.]
:Caption: And God said,
:Caption:"Let there be light,"

:[A bright explosion of light from a star in the center, with a white caption box.]
:Caption: And there was light.

:[The star with bright rays of light is shown against the horizon of a planet.]
:[The same planet horizon is shown with a clear sky above.]
:Caption: God saw that the light was-
:Voice from the planet: Can you add support for dark mode?

<noinclude>{{comic discussion}}
[[Category:Interactive comics]]
[[Category:Dynamic comics]]
[[Category:April Fools' Day comics]]
[[Category:Religion]]
[[Category:Comics with custom header texts]]
</noinclude>

3229: Grammar

2026-04-07T01:19:55Z

LandmineFlipFlop:

{{comic
| number = 3229
| date = April 6, 2026
| title = Grammar
| image = grammar_2x.png
| imagesize = 227x312px
| noexpand = true
| titletext = Communication is one of the most popular ways to transmit information, ahead of rivals such as
}}

==Explanation==
{{incomplete|This page was created recently by a EEEEEEEEEEEEEEEEEEEEE. Don't remove this notice too soon.}}

[[Miss Lenhart]] is shown teaching a classroom about {{w|grammar}}. Grammar is a system and set of rules to describe how a certain language is structured. This is useful to make communication standardized and clear with little to no difficulty for parsing. In this comic, Miss Lenhart claims that grammar is "''one'' of the most popular ways to structure a language". She also presents two alternative methods (though it could be interpreted as a list of 4 items without commas to split it up) that competed to substitute grammar, yet evidently never took off to be implemented in common speech, and also appear to be nonsensical in nature. Despite this, they've gained their own endonyms:

;Words order words random words words random good
:This form of alternative grammar arbitrarily consists of words that vaguely help understanding the overall sentence.

;EEEEEEEEEEEEEEEEEEE
:This is the strangest of the two. It might be referencing a scream as a form of communication (albeit an unreliable one)

The title text seems to continue Lenhart's lecture, as she moves to {{w|communication}}. Similar to the subject of grammar, she begins to pose some rival methods thereof, but seems to cut off before naming the first one. This may reference {{w|nonverbal communication}} (which is communication without oral means) but this is a subset of communication. Either Miss Lenhart has transferred into another mode of transmitting information to self-demonstrate (that may be impossible to render textually) or lack thereof, as the sudden stop in the middle of the sentence could be a joke for how there no other ways to convey information without communication. Still, this doesn't rule out other possible alternatives to communication, as Lenhart implies that other methods exist. Nonetheless, self-demonstrating lack of communication would not be useful here without further explanation, as abruptly ceasing to provide more information could instill confusion in her students.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

:[Miss Lenhart is teaching in a classroom. Two students can be seen sitting at desks in front of her, [[Cueball]] in the first row and [[Megan]] in the second row.]
:Miss Lenhart: '''Grammar''' is one of the most popular ways to structure a language, ahead of rival methods such as '''words order words random words words random good''' and '''EEEEEEEEEEEEEEEEEEE'''.

{{comic discussion}}<noinclude>

[[Category:Comics featuring Miss Lenhart]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Language]]

3212: Little Red Dots

2026-02-26T05:13:28Z

LandmineFlipFlop: fixed formatting from last edit

{{comic
| number = 3212
| date = February 25, 2026
| title = Little Red Dots
| image = little_red_dots_2x.png
| imagesize = 634x306px
| noexpand = true
| titletext = After a lot of analysis, I've determined that they're actually big red dots; they're just very far away.
}}

==Explanation==
{{incomplete|This page was created by a LITTLE RED BOT. Don't remove this notice too soon.}}

Cueball asks researchers in different subjects to identify "little red dots" in an image from the {{w|James Webb Space Telescope}} (referred to in the caption as "JWST").

The little red dots that the comic refers to are actually young black holes from 500-700 million years after the Big Bang in the JWST telescope, the comic instead jokingly asks several different experts their thoughts

According to the Entomologist they are: {{w|Clover mite | Clover mites}} (Bryobia praetiosa) are very small [[Red Spiders]].

According to the Computer Scientist they are: {{w|Defective pixel|Stuck pixels}}, pixels that do not work properly, and are stuck to one single color.

According to the Dermatologist they are: {{w|Cherry angioma|Cherry angiomas}}, harmless, non-cancerous skin growths made of clusters of dilated capillaries, appearing as bright red, smooth, or slightly raised spots.

According to the Graphic Designer they are: Colors of type Jasper (#d73b3e) and Vermillion (#e34234, sometimes called Cinnabar)

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

:[Caption above all the panels:]
:Astronomers asking researchers from different departments to help them identify the "little red dots" in JWST images:

:[In each panel, Cueball stands at the left of an easel. The easel is shown each time as having a black image with three red dots on it. At the right of the easel in each panel is a different character looking at the image on the easel and commenting on it. At the top of each panel is a caption indicating the type of researcher commenting on the image.]

:Caption: Entomologists
:Megan: Clover mites.

:Caption: Computer scientists
:Knit Cap: Stuck pixels.

:Caption: Dermatologists
:Ponytail: Cherry angiomas.

:Caption: Graphic designers
:Hairy: No, those are vermillion, or maybe jasper.
:Hairy: Can I see your color settings?

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Knit Cap]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Comics with color]]
[[Category:Astronomy]]
[[Category:Telescopes]]
[[Category:Biology]]
[[Category:Computers]]
[[Category:Medicine]]
[[Category:Graphic designers]]

3212: Little Red Dots

2026-02-26T05:05:17Z

LandmineFlipFlop:

{{comic
| number = 3212
| date = February 25, 2026
| title = Little Red Dots
| image = little_red_dots_2x.png
| imagesize = 634x306px
| noexpand = true
| titletext = After a lot of analysis, I've determined that they're actually big red dots; they're just very far away.
}}

==Explanation==
{{incomplete|This page was created by a LITTLE RED BOT. Don't remove this notice too soon.}}

Cueball asks researchers in different subjects to identify "little red dots" in an image from the {{w|James Webb Space Telescope}} (referred to in the caption as "JWST").

The little red dots that the comic refers to are actually young black holes from 500-700 million years after the Big Bang in the JWST telescope, the comic instead jokingly asks several different experts their thoughts

According to the Entomologist they are: {{w|Clover mite | Clover mites}} (Bryobia praetiosa) are very small [[Red Spiders]].

According to the Computer Scientist they are: Stuck pixels, pixels that do not work properly, and are stuck to one single color.

According to the Dermatologist they are: Cherry angiomas, harmless, non-cancerous skin growths made of clusters of dilated capillaries, appearing as bright red, smooth, or slightly raised spots.

According to the Graphic Designer they are: Colors of type Jasper (#d73b3e) and Vermillion (#e34234, sometimes called Cinnabar)

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

:[Caption above all the panels:]
:Astronomers asking researchers from different departments to help them identify the "little red dots" in JWST images:

:[In each panel, Cueball stands at the left of an easel. The easel is shown each time as having a black image with three red dots on it. At the right of the easel in each panel is a different character looking at the image on the easel and commenting on it. At the top of each panel is a caption indicating the type of researcher commenting on the image.]

:Caption: Entomologists
:Megan: Clover mites.

:Caption: Computer scientists
:Knit Cap: Stuck pixels.

:Caption: Dermatologists
:Ponytail: Cherry angiomas.

:Caption: Graphic designers
:Hairy: No, those are vermillion, or maybe jasper.
:Hairy: Can I see your color settings?

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Knit Cap]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Comics with color]]
[[Category:Astronomy]]
[[Category:Telescopes]]
[[Category:Biology]]
[[Category:Computers]]
[[Category:Medicine]]
[[Category:Graphic designers]]

3209: Plums

2026-02-19T06:13:45Z

LandmineFlipFlop: added a link to its wikipedia page

{{comic
| number = 3209
| date = February 18, 2026
| title = Plums
| image = plums_2x.png
| imagesize = 251x409px
| noexpand = true
| titletext = My icebox plum trap easily captured William Carlos Williams. It took much less work than the infinite looping network of diverging paths I had to build in that yellow wood to ensnare Robert Frost.
}}

==Explanation==
{{incomplete|This page was created by a rebellious icebox. Don't remove this notice too soon.}}
This is a reference to the poem [https://www.poetryfoundation.org/poems/56159/this-is-just-to-say This Is Just to Say](a poem mostly in the sense of {{w|This Is Just to Say | its rhythmic cadence}}), where the narrator is apologizing for eating the plums in the icebox. In this comic, the joke is that Cueball cannot resist eating the plums from the icebox as a reference to the poem.

The title-text is a joke about trapping poets with references to their own poems, referencing another well-known poem, [https://www.poetryfoundation.org/poems/44272/the-road-not-taken The Road Not Taken] by Robert Frost.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[Cueball sitting at a desk with a laptop on it looking backward towards the source of speech off-screen.]
:Out of view: I got you the ingredients for dinner tonight.
:Out of view: Oh, and the plums in the fridge drawer are for my yogurt tomorrow; you should just leave them.
:Out of view: Be back later!
:Cueball, thinking: Oh no.
:Caption: Help. It actually happened. I shouldn't, but how can I not!?
{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]

3206: Installation

2026-02-12T03:39:48Z

LandmineFlipFlop:

{{comic
| number = 3206
| date = February 11, 2026
| title = Installation
| image = installation_2x.png
| imagesize = 740x272px
| noexpand = true
| titletext = Do YOU remember the skylight being this big?
}}

==Explanation==
{{incomplete|This page was created by a house like carpet. Don't remove this notice too soon.}}
This comic refers to wall-to-wall carpeting, also known as {{w|Fitted carpet}}, which usually is carpeting that runs from wall to wall. Usually, the carpeting is on the ''inside''{{citation needed}} of the house where it is installed. However, in this example, Megan and Cueball are installing it on the ''outside'' of the house, walking the entirety of the earth's circumference until the finally finish installing it on the other side of their house. This method would be impractical{{citation needed}}, since it would both cross over oceans and use 40,008 to 40,075 kilometers of carpet, depending on where the house is and where it is facing.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>

2348: Boat Puzzle

2026-01-31T20:16:44Z

LandmineFlipFlop: added a line to explain the trolly into cabbages connection to the "my cabbages" gag in Avatar: The Last Airbender

{{comic
| number = 2348
| date = August 19, 2020
| title = Boat Puzzle
| image = boat_puzzle.png
| titletext = 'No, my cabbage moths have already started laying eggs in them! Send the trolley into the river!' 'No, the sailing wolf will steal the boat to rescue them!'
}}

==Explanation==
This comic is a twist on {{w|Wolf, goat and cabbage problem|an old riddle}}. In the original riddle, a person has to cross a river in a boat that can only hold them and one other object. They have a wolf, a goat, and a cabbage that they need to bring across with them, similar to the first panel. If the wolf is left alone with the goat, however, the wolf will eat the goat; and if the goat and cabbage are alone, the goat will eat the cabbage. (The problem can be solved in seven trips.)

However, the comic quickly devolves into surrealism in the later panels as new characters show up, bringing deviations of the original "cabbage", "goat", and "wolf" that add extra layers of complexity to the riddle. [[White Hat]] brings extra wolves and cabbages. [[Black Hat]], in his traditional [[72:_Classhole|classhole]] style, brings {{w|cabbage moth}}s which will infest unsupervised cabbages with destructive larvae, and boat-destroying {{w|termite}}s. How he intends to bring them across the river (or even if he wants to) is unknown, but it brings to mind the parable of {{w|The Scorpion and the Frog}}, where the scorpion stings (out of instinct) the frog ferrying it across the river. [[Beret Guy]] arrives with a wolf who can operate a boat, who could perhaps serve as a second pilot to expedite the crossing, so long as he is not asked to ferry a goat, and also a goat who eats wolves, possibly in addition to the cabbages. This is unusual,{{cn}} as one would expect from Beret Guy's associates.

The last panel is a reference to the {{w|Trolley_Problem|Trolley Problem}}, a moral test that asks the participant whether they would passively let people in the way of an uncontrollable trolley die or actively divert the trolley to kill a single person standing on a branch of the tracks. The comic gives a twist here too: according to the title text, the characters must choose between stopping the trolley full of wolves with a cushion of cabbages (in which Black Hat's cabbage moths have laid eggs, which he implicitly argues are morally equivalent to "innocent children") or letting it crash into the river (at which point the wolf who can operate a boat will steal the boat to rescue the wolves from the trolley, which will delay the other characters from crossing the river). The cushion of cabbages is also most likely a reference to the {{w|Avatar: The Last Airbender}} gag "my cabbages" in which a cabbage vendor routinely has his cart full of cabbages destroyed as a running joke.

The River Crossing puzzle was also mentioned in [[1134: Logic Boat]] and referenced in [[589: Designated Drivers]] and [[2684: Road Space Comparison]].

The Trolley Problem was also mentioned in [[1455: Trolley Problem]] and referenced in [[1938: Meltdown and Spectre]].

==Solving the problem==

Unlike typical Logic Boat problems the presence of multiple humans makes finding a solution almost trivial, however trying to determine the solution with the least number of trips could still make the somewhat challenging. Because the set of constraints are both ambiguous and incomplete, it requires the reader to make assumptions that, in turn, will lead to different solutions.

===Reasonable Assumptions===

The following assumptions can be made based on the setup of the problem or are necessary to avoid an unsolvable puzzle.

* '''Cueball is an observer.''' He is set up as an observer there to solve the problem, not pilot the boat or "watch" the cargo.
* '''The boat can only hold two items.''' This is standard in logic boat problems. Groups of insects count as one item.
* '''Black Hat and Beret Guy both want to cross the river with their cargo'''. Neither states that they wish to cross the river like Ponytail and White Hat, but it can be inferred from the setup of the scenario.
* '''The termites will destroy the boat ''after'' crossing.''' Otherwise the problem is unsolvable. This is similar to the {{w|Poncelet–Steiner theorem}}, which shows that any compass-and-straightedge construction can be completed with a "rusty compass", so long as the compass works at least once.
* '''The wolf-eating goat also eats cabbage.''' The wolf-eating constraint adds to the goat's existing constraints.
* '''The sailing wolf follows the command of an adjacent human.''' The alternatives require more assumptions for a solvable puzzle.
* '''The sailing wolf returns the trolley wolves to the near shore.''' The trolley wolves show no indication of wanting to cross the river.
* '''Stopping the trolley destroys all the cabbages.''' Otherwise the event does not affect the logic puzzle.
* '''The pack of wolves from the trolley will eat a human or wolf-eating goat left by themselves.''' Aligns with the spirit of the constraints.
** '''A wolf can protect a human from a pack of wolves'''. A human who is accompanied by one of the wolves who want to cross the river should not count as being "alone" for the purpose of getting eaten by the wolves from the trolley; otherwise, there is no way to get everyone across.

===The Trolley===

The trolley problem creates two versions of the puzzle, one where the cabbages are destroyed, the other where they are not and a wolf rescue takes place. The ethical issues associated with the trolley problem are independent from the logic of how to cross the river.

===Solutions===

* General

With four humans involved, the first trip across can bring an extra human who then can guard the cargo as it is brought across in arbitrary order with care being taken not to have predator and prey alone together at the end. The termites must be last cargo ferried across as they will destroy the boat.

* The Trolley is Stopped

The cabbages are destroyed. The second to last trip brings across the last human and the last trip brings across the termites.

* The Trolley is not Stopped

A pack of wolves is now on the near bank. The last human is brought across in the third to last trip, followed by the last wolf and lastly the termites.

===Missing Information===

No information is provided about whether or not the humans all get along with each other and this is left as a possible exercise for the reader given all of the characters' varying personality traits. However the sailing wolf would likely come in handy if certain humans (ex Black Hat, Beret Guy) cannot be left alone. It is also probable that certain characters might not serve in the capacity as a cargo guard.

It is also unclear if humans can leave with their cargo once all the cargo has been brought across. This could complicate matters if a far side "guard" leaves early.

==Transcript==
:[Cueball and Ponytail are standing on the bank of a river. There is a boat in the river. A goat and wolf are also on the riverbank, and Ponytail is holding a cabbage.]
:Ponytail: I need to cross the river. I have a wolf, a goat, and a cabbage.
:Cueball: Hmm.

:[White Hat appears, accompanied by two wolves and pulling a wagon full of cabbages.]
:Cueball: OK, here's what-
:White Hat: Hi, I also need to cross. I have two wolves and 100 cabbages.

:[Black Hat arrives, surrounded by a cloud of flying creatures and carrying a jar of bugs under his arm. Beret Guy follows with another wolf and goat on leashes.]
:Black Hat: I have 50 cabbage moths and 2,000 boat-destroying termites.
:Beret Guy: I have a wolf that can operate a boat, and a goat that eats wolves.

:[The fourth panel is a zoomed-out shot, where everything but the sky appears black.]

:[A trolley speeds in, leaving a trail of dust in its wake. A person is standing on the front, and many ears are barely visible above the seats.]

:Cueball: Hang on, I need to make a spreadsheet.
:Trolley operator: Look out!
:Trolley operator: My wolf-filled trolley is out of control and can only be stopped by a cushion of cabbages!

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Beret Guy]]
[[Category:Logic]]
[[Category:Animals]]
[[Category:Food]]

Knit Cap

2026-01-29T17:46:47Z

LandmineFlipFlop: added a line about her being a chess player

{{Infobox character
| image = Knit_Cap.png
| imagesize = 200px
| caption = '
| first_appearance = [[1037: Umwelt]]
}}

<noinclude>:''For a list of comics, see [[:Category:Comics featuring Knit Cap|Comics featuring Knit Cap]].''</noinclude>

'''Knit Cap''' is a [[stick figure]] character in [[xkcd]]. She is distinguished by her knit cap and the short hair that comes out of it.

Knit Cap was first seen in [[1350: Lorenz]], where the general consensus was that Knit Cap was a girl since she was together with [[Hairy]]. In [[1506: xkcloud]], Knit Cap is used in the [[1506: xkcloud/Transcript#User pictures|first user picture]] and in [[2198: Throw]], she is the default "You" option.

Sometimes, characters such as [[Cueball]] and [[Megan]] are seen wearing knit caps. However, it's easy to distinguish them as separate characters because their hair (if they have it) remains inside the cap and can't be seen. (The difference can be noticed in [[2902: Ice Core]].) For example, in the [[1037#Aurora|aurora story line]] in [[1037: Umwelt]], in [[1321: Cold]], and at the top of [[1732: Earth Temperature Timeline]] there are Cueballs wearing knit caps because they are in a cold environment that requires warm clothes. In [[1141: Two Years]] (and the [[:Category:X_Years|next comics in the series]]), Megan is wearing a knit cap after she lost her hair due to chemotherapy.

Knit Cap is a chess player, as seen in [[3082: Chess Position]] and [[1112: Think Logically]].

{{navbox-characters}}
[[Category:Characters]]
[[Category:Characters with hats| Knit Cap]]
[[Category:Minor characters]]