explain xkcd - User contributions [en]

3200: Chemical Formula

2026-01-28T21:00:01Z

Boonerquad:

{{comic
| number = 3200
| date = January 28, 2026
| title = Chemical Formula
| image = chemical_formula_2x.png
| imagesize = 740x225px
| noexpand = true
| titletext = Some of the atoms in the molecule are very weakly bound.
}}

==Explanation==
{{incomplete|This page was created recently. Don't remove this notice too soon.}}
The universe contains atoms such as carbon and hydrogen.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[A long panel with a chemical formula trailing off the right side]
:C1076 H1080 Ac1067 Ag1069 Al1075 Am1026 Ar1075 As1070 At1047 Au1069 B1071 Ba1070 Be
:[Caption below the panel:] The approximate chemical formula for the universe

{{comic discussion}}<noinclude>

3090: Sail Physics

2025-05-17T04:21:33Z

Boonerquad: Moved around citation needed to ease reading

{{comic
| number = 3090
| date = May 16, 2025
| title = Sail Physics
| image = sail_physics_2x.png
| imagesize = 699x263px
| noexpand = true
| titletext = Turning in other directions can be accomplished by using a magnetized centerboard and ocean currents, since a current flowing through a magnetic field induces a Laplace force.
}}

==Explanation==
{{incomplete|This page was created by a wind-blown electron. Don't remove this notice too soon.}}

This comic shows what initially appears to be an explanation of how boats sail upwind. However, it quickly devolves into wrongness, where, instead of even mentioning {{w|tacking (sailing)|tacking}}, it dives into a totally wrong explanation involving electrons and magnetism.

This humour works at another level — almost all interaction of physical things with each other at macro scale (humans and boat sized objects) are of electromagnetic in nature (this is considering, that at this scale, among the 4 fundamental interactions, only electromagnetic interactions are of reasonable strength). So one unaware of sailing mechanics may start to explain the situation with electromagnetism, and could come to this line of thinking, but it is wrong. If we are to consider this, we find that either no force is appearing in the direction shown, or very little.

{{w|Triboelectric effect|Triboelectric effect}} is the mechanism of acquisition of static charge. Though, it depends on relative frictional forces involved between two objects, which in turn depends on effective interaction surface area. But the charge acquired would be very small, and not be of comparative order of magnitudes with gravity. There is more charge generated due to running of water across the boat in a realistic situation. Then the comic assumes motion in the direction of downstream, due to effective normal forces on the sail. Then the comic considers this motion as motion of a charged object in Earth's magnetic field. If we are to consider this magnetic field to be roughly parallel to Earth's surface, which would be true for situations close to the equator (as Earth's magnetic field is effectively that of dipole bar magnet, which is roughly aligned with our planetary rotational axis (as of writing of this explanation, as the magnetic field dipole keeps on moving, and this may change)). The net Lorentz force on the boat would be F = qvB, and since both velocity of both and magnetic field lines are in the same plane (as viewed in the above sketches, in a top-down manner), then the force would be perpendicular to the plane. That is, along the direction of gravity for the boat, which will not cause any motion in plane. If we consider magnetic field lines to be perpendicular to Earth's surface (close to poles), even then the magnitude of the force is very small. If we consider a net charge of 1 coulomb across the boat (which is an extremely high amount of charge, at which point, the charge would try to accumulate on sharp objects, and due to this high charge density, either charge will leave the boat through coronal discharge, or the sharp objects would start to break from the boat (this is due to high self electrostatic energy, which is roughly proportional to square of charge density divided by radius of curvature of object, if the bonding between object is not strong enough, then this electrostatic energy can overcome this bonding energy), assuming that this charge does not cause the ship to break or the charge to leak out to water body, as the charge would like to spread to minimise the electrostatic energy), and if we consider field strength of order 0.0001 Tesla (close to typical values on surface), and take wind speeds of 10000 m/s (also very high) then the net force on ship would be 1 N, which for a boat of mass 10 kg (less for a typical boat, but is appropriate for a makeshift raft) cause a net acceleration of 0.1 m/s^2. Which is not tiny, but due to friction across the boat, would be cancelled out (by 1 or 2 orders of magnitude). This is considering the best possible case. For more reasonable charge values, this force would be about a trillion times weaker, and hence this will not cause any practical motion.{{citation needed}}

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

[Panel 1]

How sailboats use physics to sail upwind:

[A schematic boat with a sail is shown (top-down view). Winds shown with directional arrows, pointing in the direction of the sail (going towards 4:30 on a clock face).]

[Panel 2]

1. Wind passing over the sail strips away electrons via the triboelectric effect.

[Schematic similar to panel 1, but with charged ions shown across both sides of the sail, representing the triboelectric effect.]

[Panel 3]

2. The positively charged boat is blown downwind; its movement in Earth's magnetic field produces a Lorentz force.

[The same schematic, except a force vector is shown in the direction of the wind, and a perpendicular force vector (along 1:30 on a clock face) is shown with a dashed arrow.]

[Panel 4]

3. The Lorentz force acts perpendicular to the direction of motion, redirecting the boat upwind.

[A net force vector is shown perpendicular to the downstream vector.]

{{comic discussion}}<noinclude>

1051: Visited

2025-05-07T22:26:10Z

Boonerquad: Added "including this website"

{{comic
| number = 1051
| date = May 4, 2012
| title = Visited
| image = visited.png
| titletext = I hate when I read something like '... tension among the BASE jumpers nearly led to wingsuit combat ...', and I get excited because 'wingsuit combat' is underlined, only to find that it's just separate links to the 'wingsuit' and 'combat' articles.
}}

==Explanation==
This comic is a reference to how an internet browser will make the links of the pages that you have visited a different color than the links that you have not visited. In the case of {{w|Wikipedia}} and other wikis powered by {{w|MediaWiki}} (including this website), they are blue for non-visited and purple for visited. In this comic, [[Randall]] is ashamed of the pages he has visited, because with the color changes there is evidence of what he has visited in the past, e.g. {{w|autoerotic asphyxiation}} (possibly while researching [[682: Force]], which features that very Wikipedia page).

The pages that he did visit before are in great contrast with the pages that he hasn't. Pages he didn't click are often difficult, highly intelligent topics, while he only clicks the easy, funny articles with little scientific background on the Wikipedia site.

The title text refers to a common mistake many people make when reading articles on Wikipedia. Words referring to subjects that have an article on Wikipedia are colored in blue. This, however, can cause confusion when two words leading to two separate articles appear together, as the two links appear to be one. However, on hovering the cursor over the article link, only one word at a time is underlined, showing that the links are separate.

It is not possible to determine who this fake article is supposed to be about, but the Macarena band is certainly from Dos Hermanas, Spain. So, it is quite possibly a made-up article from [[Randall]].

==Transcript==
[The following is in the standard format of a Wikipedia article, modified to reflect the content of the comic. The First and Last paragraph was partially cutoff]
:...and was a pioneer of literary social realism[link not clicked].

:He was born in Dos Hermanas[link not clicked] in the Andalusia[link not clicked] region of Spain[link not clicked] (not to be confused with Andalasia[link clicked], the kingdom in Disney's ''Enchanted''[link clicked]), which is also the hometown of ''Macarena''[link clicked] band Los Del Río[link clicked],

:His third novel[link not clicked], set during the Burmese-Siamese war[link not clicked], marked the start of a lifelong interest in the history of Southeast Asia[link not clicked]. He spent his later years in Thailand[link not clicked], writing his his final novels just a few blocks from the hotel where actor David Carradine[link clicked] died of Autoerotic Asphyxiation[link clicked].

:[Caption below the panel:]
:If I go for a while without clearing my browser history, I start getting embarrassd by which words on Wikipedia show up in purple.

==Trivia==
* In the caption of the comic, embarrassed is spelled incorrectly.
* In the third paragraph, there is an extra "his" in the phrase "writing his his final novels".

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Wikipedia]]
[[Category:Wingsuit]]
[[Category:Disney]]

3083: Jupiter Core

2025-04-30T16:09:11Z

Boonerquad: Added Explanation 5

{{comic
| number = 3083
| date = April 30, 2025
| title = Jupiter Core
| image = jupiter_core_2x.png
| imagesize = 581x443px
| noexpand = true
| titletext = Juno mission data suggests that Jupiter actually contains Matryoshka doll-style nested copies of every other planet in the Solar System.
}}

==Explanation==
{{incomplete|This page was created recently by a BOT IN THE CENTER OF JUPITER. Don't remove this notice too soon.}}

{{w|Jupiter}} is the largest planet in the {{w|Solar System}}; the fifth planet from the Sun and the first {{w|gas giant}}. The core of the planet is surrounded by an enormous gaseous atmosphere, and this comic lists a number of theories about the structure of the core. The first two are theories that are or have been held by reputable scientists, the rest are ridiculous ideas from Randall's mind.

{|class="wikitable" style="margin:auto"
|-
!Number Jupiter!!Caption of Jupiter!!Explanation
|-
|1||Diffuse mix of heavy elements and metallic hydrogen||The {{w|Juno mission}} data supports this structure
|-
|2||Rocky core with metallic, hydrogen mantle||This was one of the leading proposals prior to the Juno mission
|-
|3||Valuable treasure|| obviously valuable treasure
|-
|4||Emergency backup Earth||This would be a copy of the Earth that can be put into place once we finish destroying the planet.
|-
|5||Regular planet pretending to be a gas giant to avoid attention||The joke here is that there is secretly a regular planet hiding inside Jupiter that is shy and does not want attention, so it pretends to be a gas giant. Of course, planets are not shy in real life, as they do not have feelings.{{citation needed}}
|-
|6||Hard ball from avocado|| Avocado pits are the seed of an avocado
|-
|7||Baby Jupiter, still gestating||Jupiter is so big because it's pregnant, and the core is a fetal planet
|-
|8||No core; flat Earth conspiracists are wrong about Earth but right about Jupiter||{{w|Modern_flat_Earth_beliefs |Flat Earth}} is a debunked claim{{cn}} that the Earth is not actually spherical, but flat. This version of Jupiter proposes that while Earth may not be flat, Jupiter is, so it doesn't actually have a core. Both Earth-based astronomy and flyby missions disprove this.
|}

9. Matryoshka Doll
Since Jupiter is the largest planet of the solar system, it could contain all other planets nested in each other. The order from large to small would be:
Jupiter, [most planets still missing] and the innermost could still be Pluto.

==Transcript==
{{Incomplete|better phrasing needed}}

:Current leading theories for what's in the center of Jupiter.

:[Variations of Jupiter, except for the last are shown with about 1/8 of the planet chopped off to show the core.]

:[Jupiter]
:Diffuse mix of heavy elements and metallic hydrogen

:[Jupiter with a rocky core]
:Rocky core with metallic, hydrogen mantle

:[Jupiter with a pile of coins for a core]
:Valuable treasure

:[Jupiter with Earth for a core]
:Emergency backup Earth

:[Hollow Jupiter with a rocky planet in the middle]
:Regular planet pretending to be a gas giant to avoid attention

:[Jupiter with a smooth ball for a core]
:Hard ball from avocado

:[Jupiter with a small version of Jupiter for a core]
:Baby Jupiter, still gestating

:[Jupiter as a flat circle, with nothing chopped off]
:No core; flat Earth conspiracists are wrong about Earth but right about Jupiter

{{comic discussion}}