explain xkcd - User contributions [en]

3230: Overton

2026-04-08T21:24:05Z

Gardener: /* Explanation */ clarify that it is *in the drawing* that Overton's gravestone changes

{{comic
| number = 3230
| date = April 8, 2026
| title = Overton
| image = overton_2x.png
| imagesize = 242x268px
| noexpand = true
| titletext = I think I accidentally installed an Overton window in my bedroom. A few months ago, the sun wasn't in my face in the morning, but now it is.
}}

==Explanation==
{{incomplete|This page was created by JOSEPH PAUL OVERTON, BACK FROM THE DEAD. Don't remove this notice too soon.}}

{{w|Joseph Paul Overton}} was a political scientist who created the concept of the {{w|Overton Window}}, which is the range of subjects that are politically appropriate to raise during a period of time. The first set of dates, 1960 and 2003, are the years that Joseph Paul Overton was born and died.

It is common for political commentators to state that the Overton window has "moved," meaning that the standard for which political positions are "moderate" or "extreme" changes, and in either direction. In the comic, the "Overton window" instead refers to the time span in which Joseph Paul Overton was alive. In the drawing Overton's gravestone has the dates repeatedly crossed out as the Overton window moves. This creates the ridiculous implication that Overton had multiple lives (4 in the comic), which is impossible{{cn}}.

The title text refers to the seasonal movement of sunlight, where the sun's path rises and sets further north or south over months, known as seasonal sun path changes. This shift, caused by Earth's tilt, moves between the summer solstice (highest/northernmost arc) and winter solstice (lowest/southernmost arc.) However, the character in the text believes that rather than being a natural phenomenon, the sunlight is now being let in by a literal window, which, since it is an Overton window, is capable of gradual movement.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[A gravestone is shown on some grass. On the inscription, all of the years except the last one are crossed out in red, and all except the first pair of years have the years themselves in red. The inscription is as follows:]
:Joseph Paul Overton
:<s>1960</s> - <s>2003</s>
:<s>1965</s> - <s>2011</s>
:<s>1973</s> - <s>2018</s>
:1982 -

{{comic discussion}}<noinclude>

3213: Dental Formulas

2026-03-03T15:26:42Z

Gardener: Undo revision 407374 by This isn't a good name (talk)

{{comic
| number = 3213
| date = February 27, 2026
| title = Dental Formulas
| image = dental_formulas_2x.png
| imagesize = 212x337px
| noexpand = true
| titletext = I mean, half of these are undefined. And your multiplication dots are too low; they look like decimal points.
}}

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

A {{w|dental formula}} specifies the typical number and location of teeth of each type for a given species. There are two rows, representing the upper and lower jaw, separated by a horizontal line. On each row, the number of each type of tooth is given for one side of the jaw, with dots separating the numbers. The number of {{w|incisors}} is indicated first, {{w|canine teeth|canines}} second, {{w|premolars}} third, and finally {{w|molars}}. The formula in the comic would represent 3 incisors, 1 canine, 3 premolars, and 1 molar on each side of the upper jaw, and equal numbers in the lower jaw, with the exception that there are only 2 premolars; this is the dental formula for the {{w|Felidae|cat family}}. The adult human dental formula is 2.1.2.3 for both the upper and lower jaw.

Cueball is mistakenly treating a dental formula as an arithmetic expression, with the line indicating division and the dots indicating multiplication: 3⋅1⋅3⋅1 divided by 3⋅1⋅2⋅1, giving 9/6 = 3/2. Since the numbers involved are always small natural numbers, calculating the results when treating them this way would be fairly trivial, which is why he is surprised at the effort given to studying them.

In the title text, his statement that half the formulae are undefined refers to animals that lack one of the four types of teeth in the lower jaw, leading to a zero in the lower part of the dental formula. Cueball is attempting to multiply all terms in that lower part, giving a result of zero, and then treat that as a mathematical denominator, resulting in an {{w|Division_by_zero|undefined division expression}}. He also notes that the "dots are too low", as the dots in a dental formula are {{w|Full stop|period characters}}, whereas multiplication in mathematical formulae uses {{w|Interpunct#In_mathematics_and_science|middle dot}} characters (except in the Commonwealth, where this is sometimes reversed).

The word '{{wiktionary|mammologist}}' is an alternate spelling of '{{wiktionary|mammalogist}}', meaning one who studies {{w|mammals}} (or, in some cases, specifically studying the mammaries (i.e. breasts) which mark out mammals in general). Unlike odontology (dentistry, not to be confused with {{w|odonatology}}), which studies the ''health'' of a patient's teeth, mammalogy studies teeth as a means to identify species and what they eat.

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

:[Cueball and Megan are standing in front of a whiteboard, on which is written
::<u>3.1.3.1</u><br>3.1.2.1
:along with a drawing of a tooth and some other scribbles.]

:Cueball: Do mammologists think these are hard?
:Cueball: I mean this one just evaluates to 3/2.

:[Caption below the panel:]
:Mathematicians encounter dental formulas

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Biology]]
[[Category:Math]]

3214: Electric Vehicles

2026-03-03T14:53:20Z

Gardener: /* Explanation */ link to {{w | Battery swapping}}, plus minor copy-edits

{{comic
| number = 3214
| date = March 2, 2026
| title = Electric Vehicles
| image = electric_vehicles_2x.png
| imagesize = 209x389px
| noexpand = true
| titletext = Now that I've finally gotten an electric vehicle, I'm never going back to an acoustic one.
}}

==Explanation==
{{incomplete|This page was created by an EV WITH A NON-RECHARGEABLE BOT-TERY. Don't remove this notice too soon.}}

[[Cueball]] has somehow misunderstood the way {{w|electric vehicle}}s work to be that they have one single-use battery, presumably with a vast capacity sufficient to run them for years. He should indeed feel incredibly silly about this, given the ubiquity of rechargeable batteries in other devices (including {{w|internal combustion engine}} vehicles), and the large amounts of recharging infrastructure springing up to support the running of such vehicles. His objection makes about as much sense as saying he'd never buy a gas-powered car because eventually he'd use up all the gas.

A modern electric car commonly has [https://www.iea.org/data-and-statistics/charts/evolution-of-average-range-of-electric-vehicles-by-powertrain-2010-2021 a range above 300 km/200 miles ]. By contrast, combustion engine cars usually reach at least twice this range on a full fuel tank.{{Actual citation needed}} Nevertheless, no kind of car can be driven very far or for very long without refilling its energy storage, be it liquid fuel or electrochemical potential. Many countries now have vast networks of public charging infrastructure, often for fast charging of 400kW and more, and their spacing in the all but the most sparsely populated areas usually permits any electric vehicle (even one with an unusually low range of <100km) to recharge before it runs out of energy.

Nevertheless, though not (yet) widespread, approaches for {{w | Battery_swapping | swapping batteries}} in EVs [https://www.youtube.com/watch?v=hNZy603as5w have been commercialized]. In these cases, replacing the battery does not substitute charging it, but it can potentially reduce the “refill” time from over 30 minutes to a few minutes (the time needed to pull out the discharged battery pack from the vehicle and put in a fully charged one). The batteries are charged while uninstalled and used to replace some other vehicle’s depleted battery later on.

The title text is comparing electric vehicles to electric instruments (particularly {{w|Electric_guitar|guitars}}), which are contrasted with {{w|acoustic guitar|non-electric (aka acoustic) ones}}. In the case of instruments, this doesn't refer to how they're powered, but how their sound is transmitted from the strings and amplified. There's no such thing as an acoustic vehicle, though sound ''can'' be used to [https://hackaday.com/2025/02/21/acoustic-engine-harnesses-the-power-of-sound/ generate propulsion] [https://www.youtube.com/watch?v=je7eLZS6GG0 on a small scale][https://www.youtube.com/watch?v=xCnxsoXtlmY in a variety of ways]. It has become a common practice to refer to ''bicycles'' without a motor by the misnomer 'acoustic bicycle', but this does not seem to be much the case with cars. (Bicycles are sometimes also referred to as 'analog bicycles' — this is even more of a misnomer, being borrowed from the distinction between mechanical and digital devices, where the latter are sometimes misnamed as 'electric'.)

Though it is not their intended use,{{Citation needed}} motorised vehicles can be used as music instruments. Composer Ryoji Ikeda has composed a [https://www.dazeddigital.com/music/article/37885/1/building-a-synth-orchestra-out-of-one-hundred-cars symphony for 100 thermal (acoustic) cars]. Electric vehicles are commonly designed to emit sound, sometimes like an electronic instrument, to give an audible warning of their presence for the purpose of safety. Several jurisdictions around the world require electric vehicles to emit a minimum sound level for the safety of pedestrians.{{Actual citation needed}} Above a certain speed (around 30 km/h),{{Actual citation needed}} the noise produced by wheel-to-road friction outweighs any potential engine sounds from combustion vehicles, eliminating any difference in audible noise and derived safety properties, and electric vehicles usually no longer generate artificial sound. In some cases, electric vehicle sounds are designed by [https://abcnews.com/Business/famed-composer-hans-zimmers-score-giving-sound-electric/story?id=69242502 renowned composers].

==Transcript==
:[Cueball is standing to the left side of the panel, and [[Megan]] and [[White Hat]] are standing to his right, facing him.]

:Cueball: I would never get an electric vehicle.
:Cueball: Sure, they sound great, but what do you do if the battery runs out of charge?

:[Caption below the image:]
:I felt pretty silly when someone finally explained to me that EVs are rechargeable.

{{comic discussion}}<noinclude>
[[Category: Comics featuring Cueball]]
[[Category: Comics featuring White Hat]]
[[Category: Comics featuring Megan]]

3214: Electric Vehicles

2026-03-03T10:39:13Z

Gardener: add source for electric car range

{{comic
| number = 3214
| date = March 2, 2026
| title = Electric Vehicles
| image = electric_vehicles_2x.png
| imagesize = 209x389px
| noexpand = true
| titletext = Now that I've finally gotten an electric vehicle, I'm never going back to an acoustic one.
}}

==Explanation==
{{incomplete|This page was created by an EV WITH A NON-RECHARGEABLE BOT-TERY. Don't remove this notice too soon.}}

[[Cueball]] has somehow misunderstood the way {{w|electric vehicle}}s work to be that they have one single-use battery, presumably with a vast capacity sufficient to run them for years. He should indeed feel incredibly silly about this, given the ubiquity of rechargeable batteries in other devices (including gas vehicles), and the large amounts of recharging infrastructure springing up to support the running of such vehicles. His objection makes about as much sense as saying he'd never buy a gas-powered car because eventually he'd use up all the gas.

A modern electric car commonly has [https://www.iea.org/data-and-statistics/charts/evolution-of-average-range-of-electric-vehicles-by-powertrain-2010-2021 a range above 300km]. By contrast, combustion engine cars usually reach at least 2 times this range on a full fuel tank.{{Actual citation needed}} Nevertheless, no kind of car can be driven very far or for very long without refilling its energy storage, be it gasoline or electrochemical. Many countries now have vast networks of public charging infrastructure, often for fast charging of 400kW and more, and their spacing usually permits any electric vehicle (even ones with unusually low ranges of <100km) to recharge before it runs out of energy.

Nevertheless, though not (yet) widespread, approaches for replacing batteries in EVs [https://www.youtube.com/watch?v=hNZy603as5w have been commercialized]. In these cases, replacing the battery does not substitute charging it, but it permits the “charging” time to be reduced from often over 30 minutes to a few minutes (the time needed to pull out the discharged battery pack from the vehicle and put in a fully charged one). The batteries are charged in-situ and used to replace some other car’s depleted battery later on.

The title text is comparing electric vehicles to electric instruments (particularly {{w|Electric_guitar|guitars}}), which are contrasted with {{w|acoustic guitar|acoustic ones}}. In the case of instruments, this doesn't refer to how they're powered, but how their sound is transmitted from the strings and amplified. There's no such thing as an acoustic vehicle, though sound ''can'' be used to [https://hackaday.com/2025/02/21/acoustic-engine-harnesses-the-power-of-sound/ generate propulsion] [https://www.youtube.com/watch?v=je7eLZS6GG0 on a small scale][https://www.youtube.com/watch?v=xCnxsoXtlmY in a variety of ways]. It has become a common practice to refer to ''bicycles'' without a motor by the misnomer 'acoustic bicycle', but this does not seem to be much the case with cars. (Bicycles are sometimes also referred to as 'analog bicycles' — this is even more of a misnomer, being borrowed from the distinction between mechanical and digital devices, where the latter are sometimes misnamed as 'electric'.)

Though it is not their intended use {{Citation needed}}, motorised vehicles can be used as music instruments. Composer Ryoji Ikeda has composed a [https://www.dazeddigital.com/music/article/37885/1/building-a-synth-orchestra-out-of-one-hundred-cars symphony for 100 thermal (acoustic) cars]. Electric vehicles are commonly designed to emit sound, sometimes like an electronic instrument, to give an audible warning of their presence for the purpose of safety. Several jurisdictions around the world require electric vehicles to emit a minimum sound level for the safety of pedestrians.{{Actual citation needed}} Above a certain speed (around 30 km/h){{Actual citation needed}}, the noise produced by wheel-to-road friction outweighs any potential engine sounds from combustion vehicles, eliminating any difference in audible noise and derived safety properties, and electric vehicles usually no longer generate artificial sound. In some cases, electric vehicle sounds are designed by [https://abcnews.com/Business/famed-composer-hans-zimmers-score-giving-sound-electric/story?id=69242502 renowned composers].

==Transcript==
:[Cueball is standing to the left side of the panel, and [[Megan]] and [[White Hat]] are standing to his right, facing him.]

:Cueball: I would never get an electric vehicle.
:Cueball: Sure, they sound great, but what do you do if the battery runs out of charge?

:[Caption below the image:]
:I felt pretty silly when someone finally explained to me that EVs are rechargeable.

{{comic discussion}}<noinclude>
[[Category: Comics featuring Cueball]]
[[Category: Comics featuring White Hat]]
[[Category: Comics featuring Megan]]