explain xkcd - User contributions [en]

1659: Tire Swing

2026-03-31T21:29:00Z

Boilersuit: /* Explanation */

{{comic
| number = 1659
| date = March 23, 2016
| title = Tire Swing
| image = tire_swing.png
| titletext = If we find one of those tire dumps, the next time he tries to get his truck back we can just retreat and let him have it.
}}

==Explanation==
In this comic, [[Jill]] and another girl have just completed a {{w|tire swing}}, a common makeshift {{w|swing (seat)|swing}} created by hanging a car {{w|tire}} from a length of rope, typically tied to the branch of a tree as in the comic. The other girl might at first look like she has hair like [[Megan]] but not quite as she is revealed upon zoom in to have curly hair. That they are rather small kids can be seen from the size of the tire compared to them. (They could be the same as the girls in the last panel of [[1580: Travel Ghost]]).

In the second panel of this comic Jill muses that there are huge tire dumps filled with nothing but old tires that have no use. In the last panel, Jill continues that maybe they should use a tire from such a dump next time they make a tire swing. The presumption is that perhaps they used a brand-new tire, or a tire from some other source. This is confirmed by the other girl's response (and also by the title text, see below) which makes it clear that the tire they used was in fact stolen from a guy's vehicle. The last reply from Jill suggests the victim put up a fight and they had to take the tire by force. So, these two small girls actually fought an adult man over his truck and won the fight.

Vehicle tires have a limited lifespan. The natural end of their life is when the pattern of raised treads on the circumference of the tire, which promote traction on wet roads, are worn down to a point where they are no longer effective enough, or after 6-10 years (sunlight causes the rubber to degrade, so the tire becomes prone to cracking and unsafe, even if it appears to be in good condition). Tires can also become damaged in other ways, such as puncture.

{{w|Tire recycling|Used tires}} are a notable ecological problem for a number of reasons (e.g., their size, the quantity produced, their relatively short lifespan, and the fact that they are difficult and slow to break down and contain a number of components that are ecologically problematic). A tire swing represents a functional use for otherwise useless old tires. The number of tires (it is estimated that 259 million tires are discarded annually) makes them attractive targets for recycling. More than half of used tires are ultimately simply burned for their fuel value (which prevents them from sitting in landfills indefinitely, but this may even be worse as it releases otherwise locked up carbon thus releasing this into the atmosphere and making {{w|global warming}} even worse). Some steel mills that use electric arc furnaces will mix shredded tires with their scrap when charging the furnace for both the carbon value and fuel value, in place of the coal that would otherwise be used.

The comic is thus clearly [[Randall|Randall's]] attempt to draw attention to this huge ecological problem, as he so often before has done with other climate change/global warming related comics. (Climate change, especially global warming, is a [[:Category:Climate change|recurring theme]] in xkcd). So while this is not the joke of the comic, it could be the point of it.

He also suggests another way to use old tires. It should be noted that used tires are not necessarily safe to use as a kids' toy as they could become sharp/frayed along the edges and stones and other hard/sharp objects may have become stuck in the tires (even going all the way through), during its life span, or worn thin enough to tear apart mid-swing (when the stresses on the swing material would be at their peak). So, tires bought for use as a swing may even be made from a new tire, but not necessarily of the same solid type as those used for cars. Used tires reused for a swing should be inspected for the problems mentioned above.

The title text goes further, suggesting that they actually stole the victim's entire truck - possibly just to harvest the tire needed for the swing - and that he unsuccessfully attempted to recover the truck, so they probably did fight him. He put up enough of a fight that they do not wish to fight him again (so he at least survived). Further, since the girls expect him to try again (maybe recovering the truck without all its tires), they apparently still have the truck. One of the girls suggests that if they could find one of these tire dumps, then they could take a tire from there, make a new swing, and then just walk or run away from the truck when the guy comes back, letting him have it if he really wants it so bad.

The reason Jill made this swing could be that she wishes to become a {{w|cosmologist}} as a reference back her meeting a cosmologist on a tire swing in [[1352: Cosmologist on a Tire Swing]].

Note that {{w|Calvin and Hobbes}}, which has often been [[:Category:Calvin and Hobbes|referenced in xkcd]], has done the same to Calvin's father as the girls did to the guy (though without the violence) in a [http://assets.amuniversal.com/bcb737d0b98e013340c2005056a9545d similar comic].

This was the first of two Wednesdays in a row where Randall used two children to make a reference to an environmental issue, the second being [[1662: Jack and Jill]] about {{w|hydraulic fracturing|fracking}} also with Jill.

==Transcript==
:[Jill and a girl with long curly hair, are standing under a large leafless tree as Jill adjusts a tire swing hanging from the largest of the branches of the tree. The tire hangs so high that the small girls only reach up to just above the center of the tire which has a diameter of more than half the height of the girls.]
:Jill: OK, looks good.

:[Zoom in on the girls so only the tire swing can be seen, and nothing of the tree. They both look at the tire.]
:Jill: I read that there are these huge dumps everywhere full of millions of old tires that no one knows what to do with.

:[Same setting but Jill looks up at the tree (outside the frame).]
:Jill: We should use one of those next time.
:Curly haired girl: Yeah. That guy was real mad.
:Jill: I would ''not'' want to fight him again.

{{comic discussion}}

[[Category:Comics featuring Jill]] 
[[Category:Climate change]]
[[Category:Comics featuring children]]

1660: Captain Speaking

2026-03-30T21:38:02Z

Boilersuit: /* Explanation */

{{comic
| number = 1660
| date = March 25, 2016
| title = Captain Speaking
| image = captain_speaking.png
| titletext = Oh dang, you have to pay? Hey, has anyone else paid already? If so, can I borrow your phone for a sec?
}}

==Explanation==
At periodic intervals on a commercial flight, the captain of the plane will address the passengers with information about the flight. Typically this will begin with "This is your captain speaking..." and go on to describe the progress of the flight, expected arrival time and other information about the flight such as if or when refreshments will be brought to passengers.

This comic takes this cliché and inverts it. Instead of the captain providing information, the captain tells the passengers that he has apparently forgotten everything about the flight, even down to what kind of plane he is supposed to be flying – although he does think it is a {{w|Boeing}}. He at least discovers the flight number and then plans to use the consumer app {{w|Flightaware}} that is made for tracking flights. He thus hopes to be able to find out what the destination of “his” plane is. But Flightaware requires {{w|Wi-Fi}} access, so he goes on to ask the passengers if anyone know how to access the Wi-Fi. This app was earlier referenced in [[1363: xkcd Phone]].

This even gets worse in the title text where he realizes that you have to pay for using the on-board Wi-Fi, which means he is trying to access the same Wi-Fi that the passengers have access to instead of using the on-board Wi-Fi that must be in the cockpit (to which he is supposed to have free access). Instead of just paying he then asks the passengers if someone has already paid, because then he would like to borrow their smartphone so he can check the Flightaware app to find out where they are going.

Options for explaining this scenario are:
#The "captain" is not a genuine pilot, but has somehow found himself in the position of being in charge of an airplane (this could be a reference to this earlier comic: [[726: Seat Selection]]).
#The captain has genuinely fallen asleep and has forgotten what plane he is on...but he has thus also forgotten how to navigate, determine his flight plan, or communicate with air traffic control. In the USA (where xkcd cartoons are normally set), there is normally at least a first officer and a flight attendant on the plane to support the captain.
#The captain has been drugged and shanghaied onto the plane. He is now expected to fly and land it for his "employer", but he has chosen to disclaim this fact to his passengers in the least reassuring manner possible.
#After taking-off, the captain enters a {{w|dissociative fugue}} state losing his personal identity.
#The captain has been possessed by some external entity, such as {{w|Sam Beckett}}, who arrives without the necessary knowledge to operate in the captain's original capacity.
#*The converse version would be that the “captain” is a completely normal civilian (without flying experience) who had been possessed by an entity bringing its own knowledge and intent to fly a plane. If the entity loses its hold, it therefore leaves them in a similar state of 'acquired' inexperience.
#This may be in the future, where auto-pilot is so smart and does so much of the previous job of the pilot that future pilots might forget how to fly altogether.
#The captain knows exactly where he is and where they are going, and is playing a [[Black Hat]]-style prank on his passengers.

Seeing as how planes cannot take off on {{w|auto-pilot}} (nor can they taxi, but some can actually land), and require a skilled, awake human at the controls, it is unlikely that this captain was responsible for take-off; which must mean this auto-pilot is much more advanced than current models, likely a future model, or that their first officer took off and then went away or asleep. In the event a pilot falls asleep, on medium sized planes, ground- or proximity-radar would set off an alarm waking the captain if they are on a collision course.

It is normal for the captain to sleep part of a long flight, but this can only occur if there are multiple pilots on the plane. Most flights are on auto-pilot for hours at a time, and the pilots serve primarily for takeoff, landing and emergencies. Here they are completely clueless, having to use a consumer app and asking the passengers to get flight details, instead of radioing for help as he probably should. They would easily be able to get the information of where they are going by just asking any of the passengers though.

The fact that the captain is not sure of the flight number is not hard to imagine. Commercial pilots fly multiple flights per day and the numbers all run together after a while. Every radio communication starts with the flight number, but if the captain has been out of commission for some time, the flight number could easily be forgotten. However he would probably know the aircraft type, as commercial pilots are type-rated for a specific aircraft type and with rare exceptions (e.g. Boeing 757/767) the type is specific to an airframe type. This makes it more likely that he is not professionally qualified, although he could just be rated for so many types of aircraft that it takes him a moment to determine which one is at hand (though such a veteran pilot would be unlikely to have slept through takeoff or forget how to look up flight information from the cockpit).

Three weeks later another plane related joke was released with [[1669: Planespotting]] where it is also an open question if the plane in the comic is actually a Boeing plane...

==Transcript==
:[The text is written above a Boeing 737 Next Generation seen from below as it turns left. The text emanates from the cockpit.]
:Captain: This is your captain speaking.
:Captain: Gonna be honest-I just woke up and have no idea where I am. Looks like a Boeing of some kind?
:Captain: Oh, hey, it says the flight number here.
:Captain: Okay, I'm gonna check FlightAware to figure out where we're going.
:Captain: Anyone know how to get on the wifi?

==Trivia==
*Real World Parallels:
**This comic coincided with [http://www.independent.co.uk/news/uk/home-news/british-man-goes-out-for-quiet-drink-in-essex-wakes-up-in-barcelona-a6951756.html a newspaper story] of British man, Alex Caviel, who after a night out had a vivid dream of being on a plane only to wake up to find himself on a plane landing in Barcelona.
**The comic was also published shortly after the [https://www.rt.com/news/337113-flydubai-scandal-leaks-fatigue/ Flydubai scandal], in which many pilots and former pilots accused the airline of overworking its pilots and causing massive fatigue and stress, shortly after the crash of the flight FZ981. These claims were later waged against the FlyDubai airline. The comic could portray a scenario in which one of the fatigued pilots wake up mid-flight, still suffering from lack of sleep.
**The comic was released a year and a day after the {{w|Suicide by pilot|suicide by pilot}} crash of {{w|Germanwings Flight 9525}} on 2015-03-24. This is probably a coincidence as there is no real relation to a pilot that forgets where he is, and then one that deliberately decides to crash a passenger plane killing 150 people, himself included. But for this particular flight the first officer, who crashed the plane, was left alone in the cockpit by the captain, and this was what enabled him to commit the deed. This event thus lead many companies to adopt a rule that there should always be at least two people in the cockpit at all times. But this was not always the case before, and this could explain the situation of the captain in this comic being alone in the cockpit when he "wakes" up.
**Though rare, pilots [https://www.bbc.co.uk/news/business-47691478 sometimes may not (correctly) know where they are going].
{{comic discussion}}
[[Category:Aviation]]

1660: Captain Speaking

2026-03-30T21:34:19Z

Boilersuit: /* Explanation */

{{comic
| number = 1660
| date = March 25, 2016
| title = Captain Speaking
| image = captain_speaking.png
| titletext = Oh dang, you have to pay? Hey, has anyone else paid already? If so, can I borrow your phone for a sec?
}}

==Explanation==
At periodic intervals on a commercial flight, the captain of the plane will address the passengers with information about the flight. Typically this will begin with "This is your captain speaking..." and go on to describe the progress of the flight, expected arrival time and other information about the flight such as if or when refreshments will be brought to passengers.

This comic takes this cliché and inverts it. Instead of the captain providing information, the captain tells the passengers that he has apparently forgotten everything about the flight, even down to what kind of plane he is supposed to be flying – although he does think it is a {{w|Boeing}}. He at least discovers the flight number and then plans to use the consumer app {{w|Flightaware}} that is made for tracking flights. He thus hopes to be able to find out what the destination of “his” plane is. But Flightaware requires {{w|Wi-Fi}} access, so he goes on to ask the passengers if anyone know how to access the Wi-Fi. This app was earlier referenced in [[1363: xkcd Phone]].

This even gets worse in the title text where he realizes that you have to pay for using the on-board Wi-Fi, which means he is trying to access the same Wi-Fi that the passengers have access to instead of using the on-board Wi-Fi that must be in the cockpit (to which he is supposed to have free access). Instead of just paying he then asks the passengers if someone has already paid, because then he would like to borrow their smartphone so he can check the Flightaware app to find out where they are going.

Options for explaining this scenario are:
#The "captain" is not a genuine pilot, but has somehow found himself in the position of being in charge of an airplane (this could be a reference to this earlier comic: [[726: Seat Selection]]).
#The captain has genuinely fallen asleep and has forgotten what plane he is on...but he has thus also forgotten how to navigate, determine his flight plan, or communicate with air traffic control. In the USA (where xkcd cartoons are normally set), there is normally at least a first officer and a flight attendant on the plane to support the captain.
#The captain has been drugged and shanghaied onto the plane. He is now expected to fly and land it for his "employer", but he has chosen to disclaim this fact to his passengers in the least reassuring manner possible.
#After taking-off, the captain enters a {{w|dissociative fugue}} state losing his personal identity.
#The captain has been possessed by some external entity, such as {{w|Sam Beckett}}, who arrives without the necessary knowledge to operate in the captain's original capacity.
#*The converse version would be that the “captain” is a completely normal civilian (without flying experience) who had been possessed by an entity bringing its own knowledge and intent to fly a plane. If the entity loses its hold, it therefore leaves them in a similar state of 'acquired' inexperience.
#This may be in the future, where auto-pilot is so smart and does so much of the previous job of the pilot that future pilots might forget how to fly altogether.
#The captain knows exactly where he is and where they are going, and is playing a [[Black Hat]]-style prank on his passengers.

Seeing as how planes cannot take off on {{w|auto-pilot}} (nor can they taxi, but some can actually land), and require a skilled, awake human at the controls, it is unlikely that this captain was responsible for take-off; which must mean this auto-pilot is much more advanced than current models, likely a future model, or that their first officer took off and then went away or asleep. In the event a pilot falls asleep, on medium sized planes, ground- or proximity-, radar would set off an alarm waking the captain if they are on a collision course.

Whilst it is normal for the captain to sleep part of a long flight, this can only occur if there are multiple pilots on the plane. Most flights are on auto-pilot for hours at a time, and the pilots serve primarily for takeoff, landing, and emergencies. They are completely clueless, having to use a consumer app and asking the passengers to get flight details, instead of radioing for help as he probably should. They would easily be able to get the information of where they are going by just asking any of the passengers though.

The fact that the captain is not sure of the flight number is not hard to imagine. Commercial pilots fly multiple flights per day and the numbers all run together after a while. Every radio communication starts with the flight number, but if the captain has been out of commission for some time, the flight number could easily be forgotten. However, he would probably know the aircraft type, as commercial pilots are type-rated for a specific aircraft type and with rare exceptions (e.g. Boeing 757/767) the type is specific to an airframe type. This makes it more likely that he is not professionally qualified, although he could just be rated for so many types of aircraft that it takes him a moment to determine which one is at hand (though such a veteran pilot would be unlikely to have slept through takeoff or forget how to look up flight information from the cockpit).

Three weeks later another plane related joke was released with [[1669: Planespotting]] where it is also an open question if the plane in the comic is actually a Boeing plane...

==Transcript==
:[The text is written above a Boeing 737 Next Generation seen from below as it turns left. The text emanates from the cockpit.]
:Captain: This is your captain speaking.
:Captain: Gonna be honest-I just woke up and have no idea where I am. Looks like a Boeing of some kind?
:Captain: Oh, hey, it says the flight number here.
:Captain: Okay, I'm gonna check FlightAware to figure out where we're going.
:Captain: Anyone know how to get on the wifi?

==Trivia==
*Real World Parallels:
**This comic coincided with [http://www.independent.co.uk/news/uk/home-news/british-man-goes-out-for-quiet-drink-in-essex-wakes-up-in-barcelona-a6951756.html a newspaper story] of British man, Alex Caviel, who after a night out had a vivid dream of being on a plane only to wake up to find himself on a plane landing in Barcelona.
**The comic was also published shortly after the [https://www.rt.com/news/337113-flydubai-scandal-leaks-fatigue/ Flydubai scandal], in which many pilots and former pilots accused the airline of overworking its pilots and causing massive fatigue and stress, shortly after the crash of the flight FZ981. These claims were later waged against the FlyDubai airline. The comic could portray a scenario in which one of the fatigued pilots wake up mid-flight, still suffering from lack of sleep.
**The comic was released a year and a day after the {{w|Suicide by pilot|suicide by pilot}} crash of {{w|Germanwings Flight 9525}} on 2015-03-24. This is probably a coincidence as there is no real relation to a pilot that forgets where he is, and then one that deliberately decides to crash a passenger plane killing 150 people, himself included. But for this particular flight the first officer, who crashed the plane, was left alone in the cockpit by the captain, and this was what enabled him to commit the deed. This event thus lead many companies to adopt a rule that there should always be at least two people in the cockpit at all times. But this was not always the case before, and this could explain the situation of the captain in this comic being alone in the cockpit when he "wakes" up.
**Though rare, pilots [https://www.bbc.co.uk/news/business-47691478 sometimes may not (correctly) know where they are going].
{{comic discussion}}
[[Category:Aviation]]

1921: The Moon and the Great Wall

2026-01-20T17:20:23Z

Boilersuit: /* Explanation */

{{comic
| number = 1921
| date = November 27, 2017
| title = The Moon and the Great Wall
| image = the_moon_and_the_great_wall.png
| titletext = And arguably sunspots, on rare occasions. But even if they count, it takes ideal conditions and you might hurt your eyes.
}}

==Explanation==
This is a reference to the myth that the {{w|Great Wall of China}} is the only man-made object that can be seen from the {{w|Moon}} (or from space) with the naked eye. {{w|Great Wall of China#Visibility_from_space|Sadly, it cannot}}. In fact, it's barely visible from the orbit of low satellites. Not only that, even if it were visible from space, it wouldn't be alone with that title. There are {{w|Artificial structures visible from space|plenty of objects visible from space}}; the {{w|Chernobyl Nuclear Power Plant}} is one, and so are the clusters of greenhouses in Almería Spain.

This comic mocks the myth by conflating it with another saying about the Moon, and how the Moon's craters and valleys are visible to the naked human eye. Indeed, the Moon is the only {{w|Astronomical object|celestial body}} for which this is true, as all other bodies (with the potential exception of the Sun, see the title text) can only be seen as tiny points of light by the unaided human eye. There is nothing special about the Great Wall of China in this factoid, though; the Moon’s features can be seen equally well from practically any place on Earth with a view of the Moon.{{Citation needed}}

The title text states that one is sometimes able to see large {{w|sunspots}} if any are present and conditions are ideal. However, looking directly at the sun with the naked eye risks extensive damage to the eye and should NEVER be done. It could, however, be possible to see them when the Sun is seen through a thin cloud cover or maybe at sunset/sunrise. (It's possible to see very large sunspots with {{w|solar eclipse}} {{w|Solar viewer|glasses}} or other adequate {{w|Eye protection#Protection against light|protection}}, but that's not unaided human eye.)

==Transcript==
:[Megan is holding her arm up towards Ponytail as they stand atop a large brick wall with {{w|Merlon|merlons}} along the top. They are standing to the left of a tower with three small windows as well as merlons on the top.]
:Megan: Did you know that the moon's craters and plains are the only structures on the surface of a celestial body that can be seen with the naked eye from the Great Wall of China?

{{comic discussion}}

[[Category: Comics featuring Megan]]
[[Category: Comics featuring Ponytail]]
[[Category: Astronomy]]

2823: Fossil

2025-12-17T08:04:17Z

Boilersuit: /* Explanation */

{{comic
| number = 2823
| date = September 1, 2023
| title = Fossil
| image = fossil_2x.png
| imagesize = 428x246px
| noexpand = true
| titletext = The two best reasons to get into fossils are booping trilobites and getting to say the word "fossiliferous" a lot.
}}

==Explanation==

{{w|Trilobite}}s are an extinct group of species of marine animal, one of the earliest known groups of arthropods. The first appearance of trilobites in the fossil record is from about 521 million years ago and last from about 252 million years ago. They were very common and had easily fossilized exoskeletons, so their fossils can be found very often.

In the comic, [[Cueball]] is digging at a site with [[Megan]], [[Ponytail]], and [[White Hat]] visible in the background. He finds and digs up a trilobite fossil and proceeds to {{wiktionary|boop#Verb|boop}} it (possibly because he thinks it’s cute?). "Booping" is when someone lightly taps another person, or sometimes an animal, on the nose while saying "boop", typically to annoy or as a form of endearment. In panel 2, the fossil is shown with the trilobite head pointed away from Cueball. In panel 3 he boops the head section, likely aiming for where the nose would be, if one were to imagine a trilobite having a nose. The anatomical part of the trilobite being "booped" is referred to as the glabella by palaeontologists. The glabella is located in the center of the cephalon (head), where one would expect a nose to be located.

An off-screen character yells at him for doing this, probably because fossils are often fragile and excessive touching may cause it to break, or because doing so is not showing the due respect for a once-living being that is much older than Cueball, or because Cueball might contaminate the sample, or because overly strict rules are funny.

Fossiliferous (of a rock or stratum) means containing fossils or organic remains, and [[Randall]] implies that it is a fun word to say (it really is!).

==Transcript==

:[Cueball is holding two halves of a rock in a paleontological site. Megan, Ponytail, and White Hat are working in the background.]
:Cueball: It's weird to pry open a rock and see an animal that no one has laid eyes on for 400 million years.

:[Zoom in on Cueball looking at the fossil he is holding.]

:[Cueball pokes the fossil.]
:Cueball: ''Boop!''
:Off-panel voice: Hey! Don't boop the trilobites!
{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring White Hat]]
[[Category:Animals]]

2913: Periodic Table Regions

2025-11-20T08:21:09Z

Boilersuit: /* Table Sections */

{{comic
| number = 2913
| date = March 29, 2024
| title = Periodic Table Regions
| image = periodic_table_regions_2x.png
| imagesize = 740x501px
| noexpand = true
| titletext = Cesium-133, let it be. Cesium-134, let it be even more.
}}

==Explanation==
The {{w|periodic table}} is used to arrange {{w|chemical element}}s based on their properties. This comic groups them together into regions with labels humorously reflecting their properties, characteristics, or uses.

=== Table Sections ===

{| class=wikitable
! scope="col" | Section
! scope="col" | Real table
! scope="col" | Elements contained
! scope="col" | Explanation
|-
| Slightly fancy protons || Hydrogen || Hydrogen || Most hydrogen atoms (specifically of the isotope H-1, making up 99.9844% of all hydrogen on Earth) are a proton and an electron. Since the electron can be removed (so only a proton remains) and you can call that an H+ ion, [[Randall]] calls hydrogen atoms "slightly fancy protons".
|-
| Weird dirt || Lighter alkali and alkaline earth metals || Lithium, Beryllium || Lithium and beryllium, as some of the lightest elements, have unusual properties compared to heavier metals. Lithium, for instance, is the least dense metal on the periodic table and is used in applications such as [https://www.rsc.org/periodic-table/element/3/lithium rechargeable batteries] and as a {{w|Lithium_(medication)|psychiatric medication}}. Beryllium is both toxic and transparent to X-rays, but also keeps its shape and stiffness over a wide range of temperatures, leading to its use in the primary mirrors of the [https://webb.nasa.gov/content/observatory/ote/mirrors/index.html#3 James Webb Space Telescope]. It was also used in F1, both in brake calipers and {{w|Beryllium#Applications|internal engine parts}}, before being outlawed (due to its toxicity). Also, {{w|Beryllium#Nuclear_applications|both}} {{w|Lithium#Nuclear|elements}} have nuclear applications.
|-
| Regular dirt || Middle alkali and alkaline earth metals || Sodium, Magnesium, Potassium, Calcium || Despite being metals, these are listed as "dirt" rather than "metal." Perhaps this is because they are commonly found in dirt, as they are essential nutrients for plant life and for many other forms of life, including humans.
|-
| Ends in a number, let it slumber. Ends in a letter, not much better. || Heavier alkali and alkaline earth metals || Rubidium, Strontium, Cesium, Barium, Francium, Radium || Highly reactive metals, some of which are commonly used as radioactive isotopes (which are known by a number; e.g. radium-223). The title text mentions cesium-133 and cesium-134, with the former being the only stable isotope of cesium. The phrase, "cesium-133, let it be," in the title text is a reference to the mnemonic used to remind one how to identify and to avoid {{w|poison ivy}}: "leaves of 3, let it be". The joke is that these elements are so aggressively reactive that even where stable isotopes exist, they're incredibly dangerous to handle (ie, "not much better" than the radioactive ones).
|-
| Boring alloy metals. It's probably crucial to the spark plug industry or something. (But one of them is radioactive so stay on your toes.) || The left transition metals || Scandium, Titanium, Vanadium, Chromium, Manganese, Yttrium, Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Hafnium, Tantalum, Tungsten, Rhenium, Osmium || These elements tend not to be very well known to the general public, since they're rarely primary components in anything a typical person would encounter. Nonetheless, they're used as constituents (sometimes as a small but vital trace) in alloys with specific uses, including {{w|stainless steel}}, {{w|Electric light|bulb filaments}} and {{w|Superconductivity|superconductors}}. A {{w|spark plug}} may use {{w|austenitic stainless steel}}, which includes chromium and (in some cases) molybdenum, for heat and oxidation resistance. {{w|Technetium}} is the lightest element that has no stable isotope and is thus radioactive. Technetium is commonly used in medical imaging.
|-
| Regular metals || The top transition metals || Titanium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Aluminum, Silicon || Commonly known metals (and one metalloid, silicon). These all have important uses in construction and other major industries. Titanium is extremely lightweight and creates bright white sparks. Iron is a common building material. It is used in almost everything from bridges to buildings. Nickel and Zinc are both found in American coins (Zinc makes up 97.5% of the {{w|Penny (United States coin)|penny}}). Copper is part of Gold's family and is used mostly in wires because of its conducting properties. Aluminum is also extremely lightweight like Titanium. It is used in high-stress but lightweight applications such as bike frames and airplanes.
|-
| $$$$ || The platinum group || Rhodium, Palladium, Silver, Osmium, Iridium, Platinum, Gold || Rare and highly prized metals. The most expensive of these, osmium, is worth about $1,600 per gram as of when the comic was posted. Gold, silver, and platinum are famous for being precious metals, and are commonly used in jewelry.
|-
| Weird metals || The "ordinary metals" and some transition metals || Gallium, Germanium, Cadmium, Indium, Tin, Mercury || These are more obscure than the other metals (except tin and mercury) and tend to have fewer or more specialized uses. Mercury is also the only metal that is liquid at room temperature, and gallium melts just above that at 30 °C (86 °F). Indium is one of the only metals that can be chewed like bubble gum. This is because it is non-toxic and extremely soft.
|-
| Boron (fool's carbon) || Boron || Boron || Just as {{w|pyrite}} is commonly called "fool's gold", Randall calls {{w|boron}} "fool's carbon" due to its similarities in the way both elements can make stable {{w|covalently bonded}} molecules. Many of {{w|allotropes of boron|boron’s allotropes}} are also analogous with those of carbon.
|-
| You are here || Nonmetals || Carbon, Nitrogen, Oxygen, Phosphorus || Other than hydrogen, these are all the elements required to make {{w|DNA}}, and they make up the majority of atoms in other biological molecules, thus placing you over here.
|-
| Murder weapons || Ordinary metals and metalloids || Arsenic, Antimony, Tellurium, Thallium, Lead, Bismuth, Polonium || Arsenic, thallium, lead, and polonium are highly toxic and have notorious histories as poisons. Arsenic, specifically, was a frequently used poison for murders in the 19th century. A radioactive isotope of polonium has been used for clandestine state-sponsored murders, due to the tiny amount needed for a lethal dose. Antimony and tellurium are also hazardous, though to a lesser degree. Lead is also the primary metal used for making bullets, making it a potential tool for murder in a different way. Bismuth is the odd one out, having little toxicity at all, but it is used in lead-free bullets.
|-
| Safety goggles required || The lighter halogens + some of group 16 || Fluorine, Sulfur, Chlorine, Selenium, Bromine || These elements are highly reactive, so safety goggles are required. Randall has previously mentioned the nasty properties of {{w|bromine}} at room temperature in [https://what-if.xkcd.com/50/ Extreme Boating] and the awful things you can do with {{w|fluorine}} in [https://what-if.xkcd.com/40/ Pressure Cooker].
|-
| Very specific health problems || Iodine and Radon || Iodine, Radon || {{w|Radon}} gas is formed in the radioactive decay series of uranium and thorium, which occur in trace levels in many common minerals. The gravel and concrete used in construction include such minerals, and the radon is released into the air via pores and cracks in the stone and concrete. The relatively poor ventilation in underground spaces such as basements and cellars can cause the radon to accumulate rather than be released into the environment. Eventually, the radon itself decays into other elements, which are also radioactive. Radon is chemically very inert and doesn't bind to anything, but it can still be inhaled, and its daughter elements can bind to dust particles. The radioactive materials, when inhaled, can cause damage to cells, especially in the lungs, with lung cancers as a possible long-term consequence. Iodine is a required nutrient that humans need in trace amounts to remain healthy, with an iodine deficiency typically causing thyroid problems such as goiter. Radioactive iodine is easily taken into the body, deliberately to counteract hyperthyroidism (by giving the thyroid gland radiation damage) or uncontrollably due to exposure to material in nuclear fallout/accidents. Giving high doses of 'normal' iodine would ideally flush out the problematic isotope. Even comparing the two radioactive effects, these two specific health problems are entirely unrelated, and it is only by coincidence that they are corner-to-corner on the periodic table.
|-
| Lawful Neutral || Noble gases || Helium, Neon, Argon, Krypton, Xenon || These elements are mostly non-reactive and are referred to as 'noble' as they typically do not associate with other elements. (The first three don't form chemical compounds at all, apart from things like unstable ionic complexes. The other two do form a few compounds, but these are rather difficult to synthesize and are quite reactive.)
Lawful Neutral is a reference to the {{w|Dungeons & Dragons}} alignment chart, which gives moral categories for characters. The chart goes from Lawful to Chaotic on one axis, and Good to Evil on another. Lawful Neutral means following the law without any bias towards Good or Evil, which could be exemplified by the unreactivity of noble gases. See also: [[2251: Alignment Chart Alignment Chart]].
|-
| Don't bother learning their names – they're not staying long || Astatine and Period 7 from Rutherfordium onwards || Astatine, Rutherfordium, Dubnium, Seaborgium, Bohrium, Hassium, Meitnerium, Darmstadtium, Roentgenium, Copernicum, Nihonium, Flerovium, Moscovium, Livermorium, Tennessine, Oganesson || These elements are hard to produce in large quantities and decay within hours or less... in some cases, milliseconds. (Their names haven't exactly been stable, either, with previous multiple systems of placeholder names. For example, dubnium has been called nielsbohrium, hahnium, joliotium, unnilpentium, and eka-tantalum.)
|-
| Whoever figures out a better way to fit these up there gets the next Nobel Prize || The internal transition metals || Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium|| The {{w|lanthanide}}s and {{w|actinide}}s are usually placed disconnected from the main periodic table, largely because putting them where they "should" be would [https://ptable.com/image/periodic-table-wide.svg make the chart very long]. Other {{w|types of periodic tables}} that arrange the elements exist; with the seventh period filled out the hunt is on for the eighth period which is expected to {{w|Extended periodic table|contain an extra 18 groups (columns)}}, making a redesign even more prudent than ever.
|}

The periodic table of elements has previously been the subject in [[2214: Chemistry Nobel]], [[2639: Periodic Table Changes]], and [[2723: Outdated Periodic Table]]. It is also referred to or indirectly referenced in a number of other comics, such as [[18: Snapple]], [[821: Five-Minute Comics: Part 3]], and [[1052: Every Major's Terrible]].

==Transcript==

:[A periodic table with regions labeled. Regions are marked with shapes that have rounded edges and sometimes a chemical element can be partially in two regions.]

:[Hydrogen:]
:Slightly fancy protons
:[Lithium and beryllium:]
:Weird dirt
:[4 elements below:]
:Regular dirt
:[6 elements further below:]
:Ends in a number, let it slumber
:ends in a letter, not much better
:[Left side of the transition metals group:]
:Boring alloy metals
:Probably critical to the spark plug industry or something
:(but one of them is radioactive so stay on your toes)
:[Most of the top row of the transition metals + aluminum:]
:Regular metals
:[Below the rightmost "regular metals":]
:Weird metals
:[Between "boring alloy metals" and "weird metals":]
:$$$$
:[Boron:]
:Boron (fool's carbon)
:[Top-center of p-block:]
:You are here
:[Top-right of p-block, excluding the rightmost column:]
:Safety goggles required
:[5 uppermost elements of the rightmost column:]
:Lawful neutral
:[Iodine and radon:]
:Very specific health problems
:[Below and to the right of "weird metals":]
:Murder weapons
:[Bottom row from the fourth column onwards:]
:Don't bother learning their names—they're not staying long
:[The lanthanides and actinides below the rest of the table, two rows of fifteen elements, arrow pointing to a conspicuous gap in the third column of the main table where the fifteenth would ordinarily be:]
:Whoever figures out a better way to fit these up there gets the next Nobel Prize

{{comic discussion}}

[[Category:Chemistry]]
[[Category:Nobel Prize]]
[[Category:Periodic table]]
[[Category:Dungeons & Dragons]]

2948: Electric vs Gas

2025-11-07T14:51:10Z

Boilersuit: /* Explanation */ Changed 'impractical' to 'impracticable'

{{comic
| number = 2948
| date = June 19, 2024
| title = Electric vs Gas
| image = electric_vs_gas_2x.png
| imagesize = 284x385px
| noexpand = true
| titletext = An idling gas engine may be annoyingly loud, but that's the price you pay for having WAY less torque available at a standstill.
}}

==Explanation==
{{w|Internal combustion engine|Internal combustion engines}} (ICEs) have long been the most common technology used to propel motor vehicles (usually in the specific form of reciprocating "piston" engines). In US vernacular, the most common vehicle fuel is known as "{{w|gasoline}}", or "gas" for short, leading to these engines being referred to as "gas engines". Gasoline is a product of petroleum refinement, leading to the name "petrol" being used in other dialects.

{{w|Traction motor|Electric motors}} would seem the more well-suited method for propelling a vehicle, and as early as 1885 were an actual form of motor car engine with which the fledgling internal combustion engine had to compete. Despite this early popularity, over most of the 20th century electric motors were sidelined in everyday car design, as supplying the electricity was considered to be impracticable for most forms of transportation. Modern forms are rapidly rising in popularity, and [https://www.iea.org/reports/global-ev-outlook-2024/trends-in-electric-cars now constitute 18% of all global vehicle sales]. [[Randall]] is a strong proponent of {{w|electric vehicle}}s (EVs).

In this strip, [[White Hat]] claims to be comparing the pros and cons of electric motors and gas engines. The joke is that every point he makes goes in favor of electric motors. Despite it being posed as a dilemma, it may be very clear which side of the debate White Hat is promoting. On the other hand, it may indicate that one of the things we might consider a pro in electric motors (the instantaneous power now available, exceeding that of many non-electric engines) he would consider a problem — perhaps more accurately, a problem with the ''drivers'' of such vehicles — recklessly using the enhanced capabilities to accelerate to high speeds at all opportunities, whether safe to do so or not.

The strip offers the following points in favor of electric motors:

* "Cleaner and more efficient". ICEs produce and vent harmful combustion products and toxic chemicals, while electric motors produce no emission byproducts at the point of use. The efficiency of both gas and electric motors vary, but the typical ICE vehicle in the US converts around 25% of available energy into motion, while the typical electric vehicle is in the neighborhood of 80%. Even when considering inefficiencies in the source production and transmission and storage and release of energy, battery-driven electric vehicles are generally more efficient than internal combustion propelled vehicles[https://www.factcheck.org/2024/02/electric-vehicles-contribute-fewer-emissions-than-gasoline-powered-cars-over-their-lifetimes/].
** It should be noted that all of this refers to the motors only, and ignores how the fuel and electricity are produced, or the wider environmental impact of the vehicle. Determining the overall environmental advantages of electric vehicles is a much more complex and involved calculation.

* "More powerful". Electric motors are able to deliver a lot of power from a small motor ''if'' an ample energy supply is available, and can do so 'on demand', often far quicker than a fuel-powered engine that has to put its power through a gearbox in order to service a wide range of road velocities, from standstill to the eventual top speed. Due to battery limitations, short or partial runtime use cases (such as dragsters, hand tools, yard tools, toys and electric scooters) net the most benefit from the small size of a high-powered electric motor.

* "Annoyingly loud". ICEs, by their nature, produce significant noise. Despite noise attenuation measures such as mufflers, they contribute significantly to urban noise. Properly designed electric motors are nearly silent (even if the rest of the vehicle is not). In particular, {{w|blowoff valve|turbocharger blowoff valves}} make particular noises that are completely lacking in an all-electric vehicle being driven at a similar performance level. This might legitimately be considered a problem, though, when everyone is used to a rapidly approaching vehicle providing a very noisy warning of its approach. EV makers have sometimes added [https://www.businessinsider.com/electric-car-ev-fake-engine-sound-hyundai-dodge-toyota-2023-7 fake ICE noises] to appeal to older drivers, and in the U.S. and some other countries, EVs are required to have {{w|Electric vehicle warning sounds|warning sounds}} at low speeds for pedestrian safety.
** At highway speeds, the noise of tires against the road is much louder than a properly muffled ICE, so the intrinsic quietness of an EV's motor is close to irrelevant in that context.

* "WAY less {{w|torque}} available at standstill". ICEs need to continually operate within a specific range of rotational speeds for best power and fuel efficiency (although the reciprocating engines used in most motor vehicles are still better than some others, such as {{w|gas turbine}} engines, in this regard), which means that a complex system of {{w|transmission|transmission gearing}} is needed to convert this motion into the specific speeds needed at the wheels. When starting from a standstill, this means that torque must be applied to the wheels relatively gradually to avoid stalling the engine. In addition, when a vehicle is standing still, the motor is typically idling at (very) low speed and must be sped up before it produces significant acceleration. Electric motors, in contrast, generally produce their peak torque when at a standstill. This results in electric vehicles having significantly better acceleration and engine responsiveness. Again, this could cause a legitimate problem with drivers changing from ICE to electric motors, because the new cars accelerate more than the driver is used to and provide different feedback. The audible clues of gear changes, whether from automatic or manual systems, are part and parcel of what many people have grown up with and come to rely on in anticipating what might need paying attention to.

It should be noted that White Hat is deliberately confining his arguments to electric vs gas ''motors'' rather than electric or gas-powered ''vehicles''. Doing so ignores the basic reason why internal combustion vehicles have long been the dominant form of personal, motorized transportation: hydrocarbon fuels are a very dense and fairly easy to handle form of energy ''storage''. Providing electrical power to a moving vehicle requires either that the vehicle remain in contact with a power line (as with an electric train or a tram) or else to carry a high-capacity battery (and the ability to recharge that battery in a reasonable amount of time, while stationary). More popular in the USA is a hybrid system, where a combustion engine provides at least some of the power to an electric motor, which was impractical until comparatively recently. Other methods, such as hydrogen fuel cells (a form of "combustion" that can be used more directly to form electricity), have been proposed, but remain experimental or niche, due to various barriers to adoption.

A more comprehensive comparison would include many more factors, both against and in favor of electric cars.

Issues raised with electric vehicles typically include:
* Higher cost of purchase (primarily due to the cost of batteries and, in the USA, now a 100% tariff on Chinese EVs), although partially offset by lower costs of operation
* Long charging times compared to refilling a gas tank (there are some approaches which mitigate this by operating either very high-powered chargers or a battery swap model, rather than charging in-car, but these are not widely adopted)
** The significance of this depends on individual situations. Most EV drivers charge primarily at night, and many drivers don't mind a charging break on long trips.
* Relatively limited range. This is less of an issue in modern times, as many modern EVs have ranges of ([https://ev-database.org/compare/electric-vehicle-longest-range 200-500 miles per charge] as of 2024, similar to the range of a typical ICE vehicle.
* Shortened range in hot weather and significantly shortened range in cold weather (while all vehicles have this problem, it's more pronounced in EVs compared to ICEs)
* Limited charging infrastructure compared to the prevalence of fuel stations
** Because many drivers can charge at home, fewer public chargers are needed than for gas cars.
* Higher vehicle weight, and resulting higher particulate emissions (from tires, but not brakes, because EVs' use of regenerative braking reduces wear on their traditional brakes)
* Reliance on some mineral and metal extraction industries (e.g., lithium) with capacity that lags the recent increased demands for EVs
* Increased demand on electricity production
* [https://archive.is/6xmJV Lower reliability](data possibly skewed by the [https://community.cartalk.com/t/should-i-still-avoid-the-first-model-year-of-a-new-vehicle/118110 newness of EV models]).

Other real pros of electric cars are also not mentioned:
* Lower total cost of ownership (TCO), due to cheaper fuel and lower maintenance costs. [https://www.edf.org/sites/default/files/2023-0/WSP%20Total%20Cost%20of%20Ownership%20Analysis%20July%202023.pdf]
* Can potentially "fill" them at home or while parked without having to stay with them (partially negates the issue of "long charging times".)
* Lower carbon footprint, and reduced dependence on the fossil fuel industry

Rapidly evolving technologies, government policies, and economic realities are changing the relevance and seriousness of these points over time. As of the publication of this strip, the "pros" of EVs do not seem to be universally convincing, as ICEs remain far more popular than EVs in most countries (EVs constitute a majority of new vehicle sales in only four countries: Norway, Iceland, Sweden and Finland). That said, EVs didn't exist as a viable industry 20 years ago, so the current reality reflects rapid and ongoing growth, suggesting that the advantages of EVs are gaining increasing recognition and understanding.

The degree of adoption is also likely to impact the viability of different vehicle types. Infrastructure in most countries has long been built around an assumption of ICEs, so things like fueling stations and ICE-qualified mechanics have traditionally been widely accessible. As EVs becoming increasingly dominant, this could shift, with EV charging infrastructure becoming easier to find than ICE fueling stations, and ICE mechanics potentially becoming more difficult to find. There's typically a certain level of inertia in the adoption of any new technology.

In the EU, [https://www.europarl.europa.eu/topics/en/article/20221019STO44572/eu-ban-on-sale-of-new-petrol-and-diesel-cars-from-2035-explained the sale of new ICE cars is banned from 2035] in an effort to move to EVs, and other jurisdictions are adopting similar policies.

Especially in the United States, this topic is highly contentious for political, economic, engineering, and {{w|Rolling coal|tribal}} reasons (as a quick look at the edit history of this page will confirm).

==Trivia==
The etymology of "gasoline" (commonly abbreviated to "gas") is disputed: it may refer to the gaseous {{w|state of matter}} as, though gasoline itself is generally liquid, it readily emits volatile vapours. Otherwise, it has been suggested to have derived from "Cazelin"/"Cazelline", originally a lamp-oil, sold by a man called {{w|John Cassell}} in the 19th century and much copied (including by the "Gazeline" brand) as the market and supply of such fuels expanded. In non-American english, the octane form of motor-fuel (i.e. non-diesel and excluding aviation fuel) is called "petrol" (derived from "petroleum", or 'oil of the rock'), with similar "electric vs petrol (vs {{w|Hybrid electric vehicle|hybrid}})" comparisons. The registered brand name "Petrol" (sold as a solvent, before being repurposed for use as vehicle fuel) could not be trademarked as it was already the common generic term for equivalent products. The unrefined crude mineral oil from which many different hydrocarbon products can be refined is still more widely known as petroleum. Vehicle fuel may now be partly or wholly composed of non-fossil-fuels to distance them from some of the traditional arguments against petrol/gas consumption, leave other considerations unchanged but possibly introduce {{w|Biofuel#Issues|further issues}}.

While ICE vehicles have, to date, proven more popular than electric equivalents, worldwide, bicycles have been outselling cars [https://www.bikeradar.com/features/bike-vs-car-the-sales-race since at least WWII].

==Transcript==
:[White Hat, with his palm raised, is talking to Cueball.]
:White Hat: Electric motors and gas engines each have their pros and cons.
:White Hat: On one hand, electric motors are cleaner and more efficient. On the other hand, electric motors are more powerful.
:White Hat: So it's hard to say which is better overall.

{{comic discussion}}

[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Engineering]]
[[Category:Climate change]]

3087: Pascal's Law

2025-09-16T09:21:51Z

Boilersuit: /* Trivia */ corrected spelling of 'ruina'

{{comic
| number = 3087
| date = May 9, 2025
| title = Pascal's Law
| image = pascals_law_2x.png
| imagesize = 400x459px
| noexpand = true
| titletext = Reductio ad absurdum fails when reality is absurd.
}}

==Explanation==
{{w|Pascal's law}} states that when a change in pressure occurs in a static incompressible fluid, it is transmitted throughout the fluid and the same change occurs everywhere. That same pressure is applied outward to the walls of the container. It was discovered by mathematician {{w|Blaise Pascal}} in 1653. This principle has significant implications. Because force is a product of pressure times area, static pressure can be used to exert arbitrarily large (or small) forces by using larger or smaller pistons. This is the principle underlying {{w|hydraulics}}. Also, when under gravity, liquids exert greater pressure at greater depths, but Pascal's law means that the pressure will be the same at any given depth. Consequently, even a narrow column of water, if it's tall enough, will result in high pressure at the bottom of the column. If the bottom of the column spreads out over a huge area, that pressure will remain high, exerting tremendous force.

[[Randall]] muses that, when he first heard of this law, he found it implausible, because it would be able to do things that, on the surface, appear "absurd". He then realized that, not only are these things possible, they either are or have been regularly used for practical purposes.

The strip shows a classroom in which a character (presumably Randall) is sitting, being shown an image of a simple {{w|hydraulic press}}, which demonstrates the first "absurd" concept. In the image, a large cylinder, fitted with a large piston, is weighed down by a person and a weight labeled "1000 kg". The bottom of this piston is fed by a narrow tube which rises to an opening, which contains a smaller piston which is being pushed down by hand. The notion that simply pushing a small piston down, by hand, would be able to lift over a tonne of weight seems absurd, but the very large surface of the platform means that even a relatively small pressure is able to exert large amounts of force.

The trade-off is that the cylinder has a huge volume, so any movement in the small piston would raise the platform only by a minuscule distance. The effect is an example of mechanical advantage: a small force applied over a relatively large distance is converted into a much larger force exerted over a much smaller distance. This principle is the basis of hydraulic machinery: a pressurized fluid is used to drive a piston, and the pressure is multiplied by the area of the piston to determine how much force is exerted. A relatively small pump can exert almost arbitrarily large forces with a large enough piston (with the tradeoff that it takes more time to exert that force).

A second objection Randall raises is that this principle would allow the destruction of entire mountains, with the very low-tech solution of digging tunnels and filling them with water, a technique that would have been available to ancient peoples. By digging even narrow vertical cavities with enough height, the pressure exerted by water at the bottom could become very high. If these channels feed into larger cavities, that pressure would exert across the entire area, creating forces that are potentially enough to shatter the rock face of the mountain. He points out that he later learned of the practice of ''{{w|Ruina montium}}'' ("wrecking of mountains" in Latin), which used exactly this principle. This was an ancient Roman mining technique in which small tunnels were dug into the side of a mountain. When the tunnels were filled with water, the rock adjacent to the tunnels would fracture, making it significantly easier to remove.

In both cases, Randall's attempts to disprove this law by pointing out consequences that he considers implausible fail to work, because those consequences are exactly what are observed (and can be used) in real life.

''{{w|Reductio ad absurdum}}'' ("reduction to absurdity" in Latin) in the title text is a form of argument in which something is assumed to be true and then the logic is followed until it results in an absurdity or obvious falsehood, which is taken as evidence that the original premise cannot, therefore, be true. In mathematics it's called {{w|proof by contradiction}}. In the title text, however, it is pointed out that some things that happen in the real world {{tvtropes|RealityIsUnrealistic|''are'' (or at least ''seem'') absurd}}, so it would be wrong to rely upon this method to {{tvtropes|AluminumChristmasTrees|conclude that they don't occur}}.

==Transcript==
:[At the left, a teacher is holding a pointer, pointing at a picture on the screen.]

:[The picture shows a hydraulic lift, with a small fluid vessel on the left connected to a tube at the bottom, which connects to a large vessel on the right. On top of the large vessel is a weight labeled 1000 and a Cueball. The fluid in the large vessel is labeled with an upward arrow. Megan's hand is over the small vessel, with a downward arrow indicating that she's pressing on it.]

:[Cueball, Hairbun, and Blondie are sitting at school desks going left to right.]
:Cueball: No, that can't be right.
:Cueball: If hydrostatic pressure worked that way, then you could use it to make machines that exert near-infinite force.
:Cueball: And ancient people could have demolished entire mountains just by drilling small tunnels and filling them with water.

:[Caption below comic:]
:When I first learned about Pascal's law, I tried to disprove it by showing that it would lead to absurd consequences, but it turns out hydraulic presses and ''ruina montium'' are both real things.

==Trivia==

In the image, assuming a 2,200 lb weight (1000 kg) and an adult who weighs around 200 lb, both on a circular piston with a 6-foot diameter, the water pressure would need to be about 0.6 psi to lift them. How easy that would be to hold in place depends entirely on the area of the piston that was being pushed down (the proportions in the drawing are likely off, as the piston size shown there would take more force to push down than most people could easily hold). An alternate demonstration would be to have no piston in the tube, and simply have the tube extend higher than the platform, so that the water column in the tube could exert enough pressure to keep the platform up. A tube around 16 inches higher than the bottom of the piston would be adequate to hold the entire massive weight in place.

The concept of "ruina montium" is similar to a demonstration which was attributed to Pascal himself, in which he supposedly inserted a tall, thin tube into an otherwise sealed barrel full of water. By adding water to the top of the tube, increasing pressure would be exerted inside the barrel, until it burst. This story may be apocryphal (all surviving accounts were written centuries after Pascal's death), but [https://www.youtube.com/watch?v=EJHrr21UvY8 the demonstration works], if you can get enough height.

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Jill]]
[[Category:Comics featuring Blondie]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Donald Knuth]]
[[Category:Physics]]
[[Category:Engineering]]

3087: Pascal's Law

2025-09-16T09:19:09Z

Boilersuit: /* Explanation */ corrected spelling of 'minuscule'

{{comic
| number = 3087
| date = May 9, 2025
| title = Pascal's Law
| image = pascals_law_2x.png
| imagesize = 400x459px
| noexpand = true
| titletext = Reductio ad absurdum fails when reality is absurd.
}}

==Explanation==
{{w|Pascal's law}} states that when a change in pressure occurs in a static incompressible fluid, it is transmitted throughout the fluid and the same change occurs everywhere. That same pressure is applied outward to the walls of the container. It was discovered by mathematician {{w|Blaise Pascal}} in 1653. This principle has significant implications. Because force is a product of pressure times area, static pressure can be used to exert arbitrarily large (or small) forces by using larger or smaller pistons. This is the principle underlying {{w|hydraulics}}. Also, when under gravity, liquids exert greater pressure at greater depths, but Pascal's law means that the pressure will be the same at any given depth. Consequently, even a narrow column of water, if it's tall enough, will result in high pressure at the bottom of the column. If the bottom of the column spreads out over a huge area, that pressure will remain high, exerting tremendous force.

[[Randall]] muses that, when he first heard of this law, he found it implausible, because it would be able to do things that, on the surface, appear "absurd". He then realized that, not only are these things possible, they either are or have been regularly used for practical purposes.

The strip shows a classroom in which a character (presumably Randall) is sitting, being shown an image of a simple {{w|hydraulic press}}, which demonstrates the first "absurd" concept. In the image, a large cylinder, fitted with a large piston, is weighed down by a person and a weight labeled "1000 kg". The bottom of this piston is fed by a narrow tube which rises to an opening, which contains a smaller piston which is being pushed down by hand. The notion that simply pushing a small piston down, by hand, would be able to lift over a tonne of weight seems absurd, but the very large surface of the platform means that even a relatively small pressure is able to exert large amounts of force.

The trade-off is that the cylinder has a huge volume, so any movement in the small piston would raise the platform only by a minuscule distance. The effect is an example of mechanical advantage: a small force applied over a relatively large distance is converted into a much larger force exerted over a much smaller distance. This principle is the basis of hydraulic machinery: a pressurized fluid is used to drive a piston, and the pressure is multiplied by the area of the piston to determine how much force is exerted. A relatively small pump can exert almost arbitrarily large forces with a large enough piston (with the tradeoff that it takes more time to exert that force).

A second objection Randall raises is that this principle would allow the destruction of entire mountains, with the very low-tech solution of digging tunnels and filling them with water, a technique that would have been available to ancient peoples. By digging even narrow vertical cavities with enough height, the pressure exerted by water at the bottom could become very high. If these channels feed into larger cavities, that pressure would exert across the entire area, creating forces that are potentially enough to shatter the rock face of the mountain. He points out that he later learned of the practice of ''{{w|Ruina montium}}'' ("wrecking of mountains" in Latin), which used exactly this principle. This was an ancient Roman mining technique in which small tunnels were dug into the side of a mountain. When the tunnels were filled with water, the rock adjacent to the tunnels would fracture, making it significantly easier to remove.

In both cases, Randall's attempts to disprove this law by pointing out consequences that he considers implausible fail to work, because those consequences are exactly what are observed (and can be used) in real life.

''{{w|Reductio ad absurdum}}'' ("reduction to absurdity" in Latin) in the title text is a form of argument in which something is assumed to be true and then the logic is followed until it results in an absurdity or obvious falsehood, which is taken as evidence that the original premise cannot, therefore, be true. In mathematics it's called {{w|proof by contradiction}}. In the title text, however, it is pointed out that some things that happen in the real world {{tvtropes|RealityIsUnrealistic|''are'' (or at least ''seem'') absurd}}, so it would be wrong to rely upon this method to {{tvtropes|AluminumChristmasTrees|conclude that they don't occur}}.

==Transcript==
:[At the left, a teacher is holding a pointer, pointing at a picture on the screen.]

:[The picture shows a hydraulic lift, with a small fluid vessel on the left connected to a tube at the bottom, which connects to a large vessel on the right. On top of the large vessel is a weight labeled 1000 and a Cueball. The fluid in the large vessel is labeled with an upward arrow. Megan's hand is over the small vessel, with a downward arrow indicating that she's pressing on it.]

:[Cueball, Hairbun, and Blondie are sitting at school desks going left to right.]
:Cueball: No, that can't be right.
:Cueball: If hydrostatic pressure worked that way, then you could use it to make machines that exert near-infinite force.
:Cueball: And ancient people could have demolished entire mountains just by drilling small tunnels and filling them with water.

:[Caption below comic:]
:When I first learned about Pascal's law, I tried to disprove it by showing that it would lead to absurd consequences, but it turns out hydraulic presses and ''ruina montium'' are both real things.

==Trivia==

In the image, assuming a 2,200 lb weight (1000 kg) and an adult who weighs around 200 lb, both on a circular piston with a 6-foot diameter, the water pressure would need to be about 0.6 psi to lift them. How easy that would be to hold in place depends entirely on the area of the piston that was being pushed down (the proportions in the drawing are likely off, as the piston size shown there would take more force to push down than most people could easily hold). An alternate demonstration would be to have no piston in the tube, and simply have the tube extend higher than the platform, so that the water column in the tube could exert enough pressure to keep the platform up. A tube around 16 inches higher than the bottom of the piston would be adequate to hold the entire massive weight in place.

The concept of "runia montium" is similar to a demonstration which was attributed to Pascal himself, in which he supposedly inserted a tall, thin tube into an otherwise sealed barrel full of water. By adding water to the top of the tube, increasing pressure would be exerted inside the barrel, until it burst. This story may be apocryphal (all surviving accounts were written centuries after Pascal's death), but [https://www.youtube.com/watch?v=EJHrr21UvY8 the demonstration works], if you can get enough height.

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Jill]]
[[Category:Comics featuring Blondie]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Donald Knuth]]
[[Category:Physics]]
[[Category:Engineering]]

1516: Win by Induction

2025-08-26T12:52:19Z

Boilersuit: /* Explanation */

{{comic
| number = 1516
| date = April 24, 2015
| title = Win by Induction
| image = win by induction.png
| titletext = This would be bad enough, but every 30th or 40th pokéball has TWO of them inside.
}}
==Explanation==
In the ''{{w|Pokémon}}'' franchise, human characters called Trainers capture fantastical creatures from the wild, the titular Pokémon (a shortened form of "Pocket Monsters"), and train them to battle one another. Pokémon are captured and stored in devices called Poké Balls, which shrink the creatures down to pocket size (hence "Pocket Monsters"). The anime's English dub has enshrined the phrase "''<Pokémon's name>'', I choose you!" into popular culture memory in english-speaking countries. When Trainers do battle, they often shout this phrase while throwing the ball to the ground, releasing the Pokémon at full size.

In this comic, a Pokémon chosen at some point was a {{w|Pikachu}} (the "poster child" for Pokémon, and the most publicly known type), which does not intend to engage in the battle itself. Instead, the Pikachu chooses another Pikachu to fight for it. This process then repeats itself. Behind the Pikachu with the Pokéball is a long line of other Pikachu, suggesting that this process has been going on for a while.

Nearby stands [[Cueball]], holding a closed Pokéball, and [[Megan]], looking at her watch. This suggests that Cueball intends to have his own Pokémon fight the Pikachu, but is waiting to see which enemy his Pokémon must face before the battle can actually begin (waiting in vain, if the above described process repeats indefinitely), while Megan is growing impatient with the delay. Given that Cueball is holding a closed Pokéball he has not deployed yet, Megan cannot herself be his Pokémon. She could be his opponent, a spectator, or teammate.

The joke in this comic comes from analogy with the mathematical {{w|proof by induction}}, which is a proof about a base case, followed by a never ending sequence of steps, each step leading to the next. Induction proves an assertion is true for one case, and then infers that it must also be true for all related cases. The title suggests that the process of Pikachu choosing Pikachu will never end, effectively postponing the battle indefinitely. But the title is '''win''' by induction, by which Randall implies that we have been given enough information to reason logically whether Megan or Cueball will win. We have here turned mathematical induction on its head: part of the humor in the comic is that the logic of induction doesn't work in reverse. We cannot reason about an initial case by inferring something from a related case whose proof is dependent on knowledge about the initial case. Or perhaps the "win" referred to is precisely that the battle is indefinitely postponed.

The name "induction" comes from logic and discrete mathematics, and is thus unrelated to the physical phenomena of {{w|electromagnetic induction}}; but the fact that Pikachu is an "Electric-type" Pokémon could be word play connecting the two ideas.

If there were always only a single Pikachu in each Pokéball, this would spawn an unlimited number of Pikachu growing at a constant rate. Since, as the title text notes, there are occasionally two of them in a Pokéball, this would lead to exponential growth assuming each of the spawned Pikachu in this case is bearing a Pokéball! This may be a reference to the rate of twins, which is approximately 1/30 in humans.

Pikachu was used in one of the storylines of [[1350: Lorenz]]. See all the attack moves it made [[1350: Lorenz#Pok.C3.A9mon|here]].

==Transcript==
:[There is a long queue of Pikachu extending out of the frame to the left. They are all just out from their ball, at least the last eight Pikachu's open balls lie in two parts on the ground at their feet. They are standing in front of Megan and Cueball. Cueball is holding a closed pokéball while Megan checks the time on her watch. The frontmost Pikachu, holding a closed pokéball, speaks.]

:Pikachu at the front: Pikachu, I choose ''you!''

==Trivia==
*For some reason Pikachu is drawn without its lightning shaped tail. Pikachu is also drawn rather stocky; this was common in early Pokémon media, but in recent times Pikachu's official design is much slimmer.
*In Pokémon canon, Pokémon are only allowed to hold on to an ''empty'' Pokéball when stored in a Pokéball.
*In Pokémon canon, only one Pokémon can exist in a Pokéball, contrary to the title text.
*Randall has drawn the Pokéballs with the button that opens them in the middle of the red half. Whereas in actual (modern) Pokéballs the button is located where the two different halves meet. However, in the Pokémon canon, earlier Pokéballs are shown with buttons or timers on top, though it is doubtful this is the intention, unless the infinite line of Pikachus has been continuing for over thirty years.
*The open Pokéballs are shown broken in two. While early Pokémon games occasionally stated Pokéballs could break, they are now always shown to be connected by a hinge. It is an uncommon visualization that the two halves are fully separate.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Math]]
[[Category:Video games]]
[[Category:Pokémon‏‎]]

1520: Degree-Off

2025-08-26T07:26:33Z

Boilersuit: /* Explanation */

{{comic
| number = 1520
| date = May 4, 2015
| title = Degree-Off
| image = degree off.png
| titletext = I'M SORRY, FROM YOUR YEARS OF CONDESCENDING TOWARD THE 'SQUISHY SCIENCES', I ASSUMED YOU'D BE A LITTLE HARDER.
}}
==Explanation==
[[Cueball]] (physics), [[Hairbun]] (biology), and [[Megan]] (chemistry) appear to be on a talk show stylized as a game show called Degree-Off, hosted by [[Hairy]], where representatives of different fields, try to explain why their field is the best and why to get a degree in their field. The title "Degree-Off" is a portmanteau of "{{w|Academic degree|degree}}", as in the recognized completion of studies at a school or university, and "{{w|face-off}}", a direct confrontation between people. A face-off has its roots in combat but does not always involve violence.

The host asks the physicist Cueball to go first. He light-heartedly begins to tell what appears to be long story, beginning with a {{w|Richard Feynman}} anecdote. During the {{w|Manhattan Project}} in Los Alamos, Richard Feynman got bored because of the isolation and started learning {{w|lock picking}} on the secret documents' safes. Using these new skills, he played lots of pranks on his colleagues, like leaving notes and spooking them into believing there was a spy among them (which, of course, {{w|Klaus_Fuchs|there was}}). He finishes his case with [http://en.wikiquote.org/wiki/Ernest_Rutherford a quote] from {{w|Ernest Rutherford}}, implying that his speech was quite long and winding. The quote communicates the idea that physics is the only fundamental framework, so that the job of chemists, biologists and other scientists is simply to catalog and systematize observations ("collect stamps") on phenomena too complicated to presently be fully described in terms of physics. This idea was earlier lampooned by [[Randall]] in [[435: Purity]] (and is also stated in the title text of [[1158: Rubber Sheet]]).

The biologist goes next, showing with a graph (see below) that the field of biology has helped reduce disease. She then goes on to claim that the heroes in biology (the part known as Medicine) have even "{{w|Eradication_of_infectious_diseases|slain}}" one of the {{w|Four Horsemen of the Apocalypse}}. Different traditions designate the Four Horsemen differently, but it is common for their number to include Plague or Pestilence. Hairbun claims that the field of biology has eliminated widespread {{w|Four_Horsemen_of_the_Apocalypse#As_infectious_disease|Pestilence}}. The imagery of Pestilence being thwarted by modern medicine was also used in the book {{w|Good Omens}}, by {{w|Terry Pratchett}} (of whom Randall is a fan, see [[1498: Terry Pratchett]]) and {{w|Neil Gaiman}}, where Pestilence has retired after the discovery of {{w|Penicillin}}, and been replaced by {{w|Pollution}}.

The graph shows the death rate from infectious disease in the USA with the range of 1900-2000. The spike is attributable to the {{w|1918 flu pandemic}}. It has been published in the paper [http://jama.jamanetwork.com/article.aspx?articleid=768249 Trends in Infectious Disease Mortality in the United States During the 20th Century].

The woman then goes on to directly accuse Cueball (i.e. physicists) of creating a new Horseman to replace the one slain by the biologists. She refers to the development of the {{w|atomic bomb}}, which was built and tested in the {{w|New Mexico desert}}. The new horseman is therefore the atomic bomb, or the various perils associated with it.

The woman's implied condemnation of the physics community has been echoed by some of the scientists involved in the project itself. After the test detonation of the first nuclear weapon on July 16, 1945, {{w|J. Robert Oppenheimer}}, the director of the {{w|Los Alamos National Laboratory}}, found himself inwardly quoting the {{w|Bhagavad Gita}}: "Now I am become Death, the destroyer of worlds." {{w|Kenneth Bainbridge}}, the organizer of the actual Trinity test (which he called a "foul and awesome display"), remarked more prosaically to Oppenheimer that day, "Now we are all sons of bitches."

This harsh moral judgement shocks Cueball, who exclaims "I thought this was supposed to be fun and lighthearted!" While the set-up is of a frivolous friendly competition, the woman's presentation is surprisingly dark. Her retort in the final panel reveals that she was angered by the off-hand dismissal of 'soft' sciences as "stamp-collecting" and turned the game from a light-hearted fun into something more serious.

In the title text the biologist goes on to declare in {{w|All caps}} that she is surprised a physicist isn't "harder", after all their condescending towards the "squishy" sciences. The use of 'hard' and 'squishy' is a play on the colloquial division between the so-called 'hard' sciences (such as physics and chemistry) and 'soft' sciences (such as biology and geology). 'Hard' sciences usually refer to the perception that in fields like physics, precisely repeatable experiments and measurements are possible, as opposed to 'soft' sciences seen as placing less emphasis on precisely quantifiable predictability - however Hairbun is extending 'hard' to its meaning of 'stoic', mocking Cueball for not being able to weather a personal moral attack. Again, she is indicating that she's upset by directly referencing a mocking portrayal of other fields allegedly made by Cueball.

To be fair to Cueball, the outbreak of disease is more a topic for epidemiology, and biology has spawned multiple diseases, atrocities, and bad movies. However, the Manhattan Project marked the first time in history that humanity possessed the ability to destroy itself — and shortly thereafter humanity got {{w|Cold War|perilously close to doing so}}.

In [[520: Cuttlefish]] Randall shows that he personally respects biologists — or at least fears them.

Within a year Randall has made several other comics about nuclear weapons, this one was the first of these the second, [[1539: Planning]], came out just 1½ month after this one and after that these two were released early in 2016: [[1626: Judgment Day]] and [[1655: Doomsday Clock]]. Nuclear weapons are also mentioned twice in ''[[Thing Explainer]]'', specifically they are explained in the explanation for ''Machine for burning cities'' about {{w|Thermonuclear weapon|thermonuclear bombs}}, but they are also mentioned in ''Boat that goes under the sea'' about a submarine that carries nuclear missiles. All three comics and both explanations in the book, does like this comic, comment on how insane it is that we have created enough firepower to obliterate Earth several times (or at least scourge it for any human life).

==Transcript==
:[Hairy is acting as the host of a TV talk show, ''Degree-Off'' holding a microphone up. Cueball, Hairbun, and Megan are acting as representatives of physics, biology, and chemistry, respectively. They each stand behind their own lectern with the respective subject label.]
:Hairy: Welcome to the '''''Degree-Off''''', where we determine which field is the best! Physics, wanna go first?
:Cueball (Phys): Sure! I'd like to tell the story of Richard Feynman's Manhattan project lockpicking pranks...
:Labels: Phys Bio Chem

:[Zoom in so Megan is no longer visible. Cueball lifts his hand]
:Cueball (Phys): ...and as he said, "all science is either physics or stamp collecting."
:Cueball (Phys): Thank you.
:Hairy: ''Great!'' Bio, you wanna go next?
:Hairbun: Okay.
:Labels: Phys Bio

:[Zoom in on Hairbun so only she and her lectern are shown. A graph is shown above her. There is a label for the y-axis to the left of the axis which has four ticks with numbers. The x-axis is a timeline without ticks but three years indicating the start center and end of the axis. The graph shows a curve falling off, with one great spike up around 1920.]
:Y-axis label: Per 100,000
:Y-axis:
::800
::600
::400
::200
:X-axis: 1900 1950 2000
:Hairbun (Bio): This is a graph of the death rate from infectious disease in this country.
:Labels: Bio

:[Zoom back to original scene with Hairy holding the microphone down and Hairbun raising her left hand, while Cueball looks at her.]
:Hairbun (Bio): The heroes of my field have '''''slain''''' one of the four horsemen of the apocalypse.
:Labels: Phys Bio Chem

:[Zoom in on only Cueball and Hairbun who is pointing aggressively at Cueball who leans away from her one hand on his lectern for support.]
:Hairbun (Bio): While the heroes of '''''your''''' field gathered in the desert to create a new one.
:Labels: Phys Bio

:[Zoom back to previous scene all are holding their hands down.]
:Cueball (Phys): ...Jeez, what the hell? I thought this was supposed to be fun and lighthearted!
:Hairbun (Bio): '''''You must have been thinking of stamp collecting.'''''
:Labels: Phys Bio Chem

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Hairy]]
[[Category:Science]]
[[Category:Timelines]]
[[Category:Line graphs]]
[[Category:Physics]]
[[Category:Biology]]
[[Category:Portmanteau]]
[[Category:Nuclear weapons]]

1521: Sword in the Stone

2025-08-26T07:21:31Z

Boilersuit: /* Explanation */

{{comic
| number = 1521
| date = May 6, 2015
| title = Sword in the Stone
| image = sword in the stone.png
| titletext = That seems like an awful lot of hassle when all I wanted was a cool sword.
}}

==Explanation==
In this comic, [[Megan]] pulls a sword out of a stone. A flash of light comes down and music plays, and a heavenly voice tells her she has ascended to the {{w|throne of England}}. Megan then pulls out her phone and searches on Wikipedia for {{w|England}}. After having read for a while, she decides she does not want the throne of England and slowly places the sword back into the rock, without taking her eyes off the text.

The comic references the fables of {{w|King Arthur}} and the {{w|Knights of the Round Table}}. In Arthurian legend, whoever can remove {{w|Excalibur#Excalibur and the Sword in the Stone|The Sword in the Stone}} is the lawful king of Britain (although this comic, as some versions of the legend, refers incorrectly to England). Arthur is an orphan being raised in secret; he notices the sword, removes it, and is proclaimed king. The sword is sometimes identified as {{w|Excalibur}}, although in other versions Excalibur was acquired by King Arthur from the {{w|Lady of the Lake}}. The most familiar version of this story is {{w|The Sword in the Stone (novel)|The Sword in the Stone}} by {{w|T. H. White}} which is based on {{w|Le Morte d'Arthur}} by {{w|Sir Thomas Malory}}. The animated {{w|The Sword in the Stone (film)|musical}} by Walt Disney is a well-known version of this fairytale based on White's book.

A key element in the joke is that as Megan begins to read about England, especially information concerning being an English ruler, she quickly thinks better of this and begins to put the sword back in its place. The punchline that Megan puts the sword back after reading about England suggests that the "gift" of being the leader of England is not worth the risk and/or work associated. British history is rife with monarchic strife, and a brief inquiry into their {{w|List of monarchs of the British Isles by cause of death|causes of death}} will show that almost one in three {{w|British rulers}} have died either in battle or from murder, etc: Queen Elizabeth II, who was alive at the time of the comic's release, is the only English monarch to die of (exclusively) old age. This would quickly lead most people to conclude that the risks associated with ruling England far outweigh the benefits.

The title text furthers this plot, having Megan comment on the hassle when the only thing she was interested in was the cool sword. Apparently, Megan is not enthusiastic about power, and her choice is made when she sees how problematic it could be to reign over the country of England. There is also a subtle play on the fact that in the T. H. White version, Arthur likewise is unaware of the significance of pulling the sword from the stone - he is simply looking for a sword to replace the one belonging to his step-brother Kay that was stolen under his watch, to avoid embarrassment and reproach.

From the time of the {{w|Roman Empire}} all the way up to {{w|Charles II of England|Charles II's}} reclamation of the throne, the area now known as England has seen {{w|Invasions of the British Isles|several migration waves, Viking raids, invasions}} and fierce power struggles among aristocratic families. Besides the constant threat of usurpation, as evidenced by the numerous wars for the crown, such as the {{w|Norman conquest of England|Norman conquest}} and the {{w|War of the Roses}}, there were also constant difficulties in managing the frontier regions. This can be seen from {{w|Hadrian's Wall}}, a creation of the titular Roman Emperor designed to keep the ever-difficult Scots out of the areas of Roman control (the Scots would be a {{w|Anglo-Scottish Wars|constant problem}} for England up until the reign of King {{w|James VI and I}}; think of the movie {{w|Braveheart}} for a good example of the regular headaches they caused, seen from the English point of view), as well as the {{w|List of Anglo-Welsh Wars|Welsh uprisings}} that occurred with such consistency that you could set your watch by them.

It is worth emphasizing that the term "England" is anachronistic in this context. At the time Arthur supposedly existed, there was no England — England was formed by Germanic tribes who {{w|Anglo-Saxon settlement of Britain|settled in Britain between the fifth and seventh centuries}}. In many of the stories, including the earliest, Arthur was in fact depicted as a leader of the native Romano-Britons in their attempts to repel these invaders. England would not exist had Arthur succeeded. The anachronism is not new; it entered Arthurian legend in the Middle Ages. (Thomas Malory's ''Le Morte d'Arthur'', for example, refers to Arthur as King of England.) In Arthurian legend, it was stated that Arthur would return when needed (in some versions he was explicitly associated with the {{w|Mab Darogan}}, a Welsh Messianic figure who would finally drive the English out of Britain and reclaim it for the native Britons). It is possible that Megan in this comic is a 21st-century reincarnation of Arthur.

The timing of this comic might relate to the birth of princess {{w|Princess Charlotte of Cambridge|Charlotte Elizabeth Diana}} on May 2, 2015, just four days before this comic, and the burden of a royal of having a whole life in public shaking hands with strangers. Since {{w|Succession to the Throne Act, 2013|2013}} the {{w|Line of succession to the British throne|line of succession}} was changed to {{w|Primogeniture#Absolute primogeniture|absolute primogeniture}}, meaning that she will keep her current position in the line (3rd after her {{w|Prince George of Wales|older brother}}) even though she now has a {{w|Prince Louis of Wales|little brother}}. Before this year, that would not have been the case, as the male gender took precedence over birth order.

It is also probably not a coincidence that this comic was published the day before the {{w|United Kingdom general election, 2015|UK General Election}}, occurring on May 7, 2015. This election decides the modern-day leader of the UK. And the problems they face today may even be more likely to cause Megan to give away the throne, than the risk of untimely death she would have faced in Arthur's days. A similar Wikipedia gag appears in [[911: Magic School Bus]]. The sword in the stone also appears in [[2578: Sword Pull]].

==Transcript==
:[Megan walks up to a sword in a stone.]

:[Megan attempts to pull the sword out of the stone.]

:[A beam of light and music plays as she removes the sword.]

:[While standing with the swords a voice from the sky speaks in gray shaky letters:]
:Celestial voice: ''The Throne of England is yours''

:[Megan takes out her smart phone and searches:]
:Wikipedia
:England

:[Megan reads on her phone.]

:[Megan, still reading from her phone, starts to replace the sword back into the stone.]

{{comic discussion}}
[[Category:Comics featuring Megan]]
[[Category:Wikipedia]]
[[Category:Fiction]]

1522: Astronomy

2025-08-26T07:13:36Z

Boilersuit: /* Explanation */

{{comic
| number = 1522
| date = May 8, 2015
| title = Astronomy
| image = astronomy.png
| titletext = Astrobiology is held back by the fact that we're all too nervous to try to balance on the ladder while holding an expensive microscope.
}}

==Explanation==
For objects at a great distance one can achieve a better view by using a {{w|telescope}} as it is the typical method in {{w|Astronomy}}. Looking through a lens or a {{w|microscope}} in {{w|biology}} and other disciplines does magnify short distant objects. And a {{w|magnifying glass}} works more like a microscope when your eye lens is close to the {{w|focus}} of the magnifying glass, but when looking at distant objects you have to increase the distance between the glass and your eye where the {{w|focal length}} of your magnifying glass must be increased to meters instead of centimeters or less on a close view. But in general a {{w|Galilean Telescope}} works on the same principle as a magnifying glass together with your eye lens, the magnifying glass only has to have a long focal length which is optimized for far distances.

In the comic, the objects being viewed by Megan could be {{w|stars}}, {{w|galaxies}} and the {{w|planets}} of our {{w|Solar System}}. [[Megan]] is using a telescope. [[Beret Guy]] attempts to view them using a step-ladder to get closer to the stars, and then looking at them through his simple hand-held magnifying glass. This approach could be successful only if the stars were a few meters away, so that the ladder would take him within a few centimeters of the study object. In fact the visible stars are several {{w|light years}} away (typically 18-20 orders of magnitude further away) and getting two meters up on a ladder won't make any perceptible difference.{{Citation needed}} (Unless, of course, you are Beret Guy.)

The title text assumes (for comic effect) that the only thing wrong with Beret Guy's strategy is the instability of the ladder endangering the expensive microscopes used by biologists for {{w|Astrobiology}}. Astrobiology is the study of life (or the possibility thereof) elsewhere in the universe, and here it would be the planets and moons in our Solar System or {{w|exoplanets}} they needed to look at. This is the second comic related to studying exoplanets in two weeks, the first being [[1517: Spectroscopy]] (see more references there).

Since we cannot go there, they do, of course, not use any microscopes in the direct studies. However, one typical magnifier in biology is the {{w|electron microscope}}, used to study {{w|microbiology}}, and they cost a lot and are very heavy. It is therefore inadvisable to carry one up a ladder, and it could possibly become very expensive if you did try it anyway.

==Transcript==
:[In front of a starry black sky, Megan looks at the stars through a telescope about twice her size, touching it at the base. She remains in the exact same position through all four panels.]

:[Beret Guy enters the panel holding a ladder and a magnifying glass.]

:[Beret Guy places the ladder next to Megan and her telescope. The ladder stands like a triangle, is slightly larger than Megan, but smaller than the telescope.]

:[Beret guy climbs to the top of the ladder, and looks at the stars through a magnifying glass.]

==Trivia==
Usually, however, Beret Guy has [[:Category:Strange powers of Beret Guy|strange powers]], so it's quite possible that his method would yield similar or even better results than Megan's approach; see for instance [[1490: Atoms]]. Given his naivety, it's also possible he just doesn't realize they should look any different. His naivety of astronomy is demonstrated in [[811: Starlight]].

The history of astronomy is filled with drastic misunderstanding of distances to celestial bodies, even up to the present day like [[Randall]] has covered in [[1342: Ancient Stars]]. Thus, the comic could be in reference to the general overestimation of distances, albeit taken to the opposite extreme.

{{comic discussion}}
[[Category:Comics with inverted brightness]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Beret Guy]]
[[Category:Strange powers of Beret Guy]]
[[Category:Telescopes]]
[[Category:Science]]
[[Category:Astronomy]]
[[Category:Biology]]

1541: Voice

2025-08-24T16:03:11Z

Boilersuit: /* Non-human entity trying to behave like a human */

{{comic
| number = 1541
| date = June 22, 2015
| title = Voice
| image = voice.png
| titletext = Anyway, we should totally go watch a video story or put some food in our normal mouths!
}}

==Explanation==
During a casual talk with [[Megan]], [[Ponytail]] suddenly interrupts her normal speech stating that she is for some reason only capable of controlling her own voice once every six years. Apparently only for a very brief time since she immediately returns to the casual talk, continuing her previous sentence mid-word before being able to tell Megan how she could help her. Upon Megan's confused request, she denies knowledge of the occurrence, although in a somewhat suspicious way, using possibly fake laughter.

It could be this was just a prank by Ponytail, to tease Megan, but given her fake laughter reply to Megan's inquiry and the continuing comment in the title text it seems most likely that Ponytail is indeed possessed by some sort of entity that prevents her from expressing her own thoughts, except for a very short time every six years. Of course this may just be her way of continuing with the prank; see a previous case of such a prank [[#Voice hijacking|below]].

In case it is not a prank it would thus appear that Ponytail's usual "self" is indeed this possessing entity. Whether this entity is actually aware that the "real" Ponytail did speak, or if it actually does not know that it was interrupted (since it continued mid-word) is not clear from the last response to Megan.

The title text suggests that Ponytail {{tvtropes|BodySnatcher|is possessed by some sort of inhuman entity}} (most likely an alien or {{w|AI}}, or possibly a [[1530: Keyboard Mash|small but intelligent creature]] living in her head) unfamiliar with movies and eating. See below for [[#Related comics|related comics]].

===Related comics===
====Non-human entity trying to behave like a human====
The comic [[1530: Keyboard Mash]] also revolves around the same theme of a non-human entity trying to convince other humans that it is in fact a human. This is most clearly referenced in the title text of this comic. In Keyboard Mash, it is a spider that tries to chat like it was a human, making statements that are true if you are human, but which humans would never utter in a conversation like here - ''put some food in our normal mouths!'' However, the pretended 'human' being (the spider) is not seen by the other person in this comic, as opposed to this one where Megan speaks directly with Ponytail.

====Voice hijacking====
It has already been established recently, in [[1528: Vodka]], that Ponytail's voice can be hijacked by non-human entities. That time it was the vodka she was drinking that took over. It is possible that this is continuing or caused by the same openness to possession as shown here. It is also possible that she simply thinks possession jokes are funny and once again jokes with Megan.

====Six years ago====
Six years to the day before this one, which according to this comic was the last time Ponytail had control of her own voice, this comic [[600: Android Boyfriend]] was posted. Ponytail acquired an android boyfriend. It seems unlikely that this older comic has any relation with this particular episode - except that this comic mentions a six-year period and Ponytail is also in that comic.

====Note on Ponytail====
''Ponytail is mainly a filler character, showing up when two females are needed or when a large group of people are present.''

It is important to note that [[Ponytail]], like most xkcd [[stick figure|stick figures]], usually does not represent the same character in each comic. This Ponytail is likely unrelated to other instances of Ponytail.

==Transcript==
:[Megan and Ponytail are walking.]
:Megan: Are you doing anything later?
:Ponytail: I was th- ''I can only control my voice once every six years. Please, you have to'' -inking of going out, but no real plans.
:Megan: ...What was that?
:Ponytail: Haha, what?

==Trivia==
*{{w|Demonic possession|Possession}} stories are common in films and books. Some recent examples that could have inspired this comic could be one of these (beware of '''spoilers'''):
**In the film {{w|The Host (2013 film)|The Host}} the human race has been taken over by small parasitic aliens called "Souls" that inserts themselves individually into a host body where they are then able to access the host's memories. In the story the main character is the host that controls a body, and then the personality of that body, which is then no longer able to control her body, but can speak to the host. And in a few situations can take over her body for a short period. Very similar to what happens in this comic.
**The Yeerks from the ''Animorphs'' {{w|Animorphs|books}} and {{w|Animorphs (TV series)|TV series}} take humans as a host by entering and merging with their brain through the ear canal. The host can fight to temporarily take back control, but this is very painful. However how many times human can fight back is not as specific as in this comic. Animorphs is referenced in [[:Category:Animorphs|a few other comics]].
**In the movie {{w|Being John Malkovich}} the main character possesses Malkovich, but Malkovich is occasionally able to communicate through the possession.
**In {{w|Warlord (Star Trek: Voyager)|an episode}} of {{w|Star Trek: Voyager}}, Kes is taken over by a warlord who has discovered a means of immortality by using technology to transfer his consciousness to another body. The warlord enters a mental struggle with Kes's latent mind, and as he begins to lose the battle, Kes's personality resurfaces on several occasions.

{{comic discussion}}
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]

1573: Cyberintelligence

2025-08-15T08:33:47Z

Boilersuit: Improved and clarified wording

{{comic
| number = 1573
| date = September 4, 2015
| title = Cyberintelligence
| image = cyberintelligence.png
| titletext = We had gathered that raw information, but had yet to put it all together.
}}

==Explanation==
[[Ponytail]] presents a FY2015 ({{w|Fiscal Year}} for 2015) budget for [https://en.wiktionary.org/wiki/cyberintelligence cyberintelligence], but is then interrupted with a snide remark about the prefix ''{{w|cyber}}''. Although it is not specified what organization the budget is for, the size of the budget ($8.1 Billion) is large enough to suggest that it must be a large government organization such as the United States Department of Defense.

This comic illustrates that some organization spends obscene amounts of money on their "cyberintelligence" budget, yet all that spending appears not to have informed them that the prefix "cyber-" fell out of fashion years ago. The suggestion that the prefix could annoy experts was already used in the title text of [[1084: Server Problem]].

The prefix "cyber" is derived from "{{w|Cybernetic}}," which comes from the Greek word {{w|Cybernetics#Etymology|κυβερνητικός}}, meaning skilled in steering or governing. Cyberintelligence could also be called {{w|cyber spying}} i.e. spying in the digital world, one of many "new" [https://en.wiktionary.org/wiki/Category:English_words_prefixed_with_cyber- words with the cyber- prefix]. Many were invented in the 1980s and 1990s, following the example of "{{w|cyberspace}}", popularized by {{w|William Gibson}} in 1982.

If cyberintelligence departments were given names today, they might be called Internet Intelligence, Virtual Intelligence, Data Intelligence or Online Intelligence departments.

This may be due to the fact that government organizations are typically named by middle-aged or senior officials who are generally less likely to be familiar with the current trends in technology language. They are more likely to stick to the words that were used when they first learned about the technology. Such organizations, being bureaucracies, are also unlikely to change their name.

The title text continues the joke by implying the organization learned about the demise of "cyber-" yet failed to process or analyze that data. It is a common problem among intelligence organizations to gather "raw information" (such as photos, or reports from spies) but be unable to make use of it because there wasn't time to process the information into intelligence by determining what it means. This is particularly true for intelligence gathered by or relating to computers, as they can generate data far faster than people can review it. It may also be a reference to the previous comic, which was a link to a survey for xkcd readers.

"Cyberspace" and "{{w|cybernetics}}", illustrated [https://books.google.com/ngrams/graph?content=cyberspace%2Ccybernetics&year_start=1990&year_end=2008&corpus=15&smoothing=0&direct_url=t1%3B%2Ccyberspace%3B%2Cc0%3B.t1%3B%2Ccybernetics%3B%2Cc0 here], are two of the most common words with that prefix (Cyberspace 6 times as prevalent as cybernetics at their peaks). "Cyberintelligence" is shown [https://books.google.com/ngrams/graph?content=cyberintelligence&year_start=1990&year_end=2008&corpus=15&smoothing=0 here]. Cyberspace was used 4000 times more often, although the more common spelling splitting it in two words "Cyber intelligence" was 1.35 times more [https://books.google.com/ngrams/graph?content=cyber+intelligence&year_start=1990&year_end=2008&corpus=15&smoothing=0 used] than in one word. But even combining these two versions cyberspace is still used more than 1700 times as often.

==Transcript==
:[Ponytail, pointing at a chart to her left, with text and two curves on a graph, is talking to someone off-screen to the right.]
:Ponytail: Our overall FY2015 cyberintelligence budget was $8.1 billion-
:Off-screen voice: -Yet it wasn't enough to pick up on the fact that no one else has used the prefix "cyber-" for like a decade?
:Ponytail: Shut up.

{{comic discussion}}
[[Category:Comics featuring Ponytail]]
[[Category:Computers]]
[[Category:Internet]]
[[Category:Line graphs]]

1573: Cyberintelligence

2025-08-15T08:31:15Z

Boilersuit: Undo revision 384219 by 90.209.85.113 (talk)

{{comic
| number = 1573
| date = September 4, 2015
| title = Cyberintelligence
| image = cyberintelligence.png
| titletext = We had gathered that raw information, but had yet to put it all together.
}}

==Explanation==
[[Ponytail]] presents a FY2015 ({{w|Fiscal Year}} for 2015) budget for [https://en.wiktionary.org/wiki/cyberintelligence cyberintelligence], but is then interrupted with a snide remark about the prefix ''{{w|cyber}}''. Although it is not specified what organization the budget is for, the size of the budget ($8.1 Billion) is large enough to suggest that it must be a large government organization such as the United States Department of Defense.

This comic illustrates that some organization spends obscene amounts of money on their "cyberintelligence" budget, yet all that spending appears not to have informed them that the prefix "cyber-" fell out of fashion years ago. That the prefix could annoy experts were already used in the title text of [[1084: Server Problem]].

The prefix "cyber" is derived from "{{w|Cybernetic}}," which comes from the Greek word {{w|Cybernetics#Etymology|κυβερνητικός}}, meaning skilled in steering or governing. Cyberintelligence could also be called {{w|cyber spying}} i.e. spying in the digital world, one of many "new" [https://en.wiktionary.org/wiki/Category:English_words_prefixed_with_cyber- words with the cyber- prefix]. Many were invented in the 1980s and 1990s, following the example of "{{w|cyberspace}}", popularized by {{w|William Gibson}} in 1982.

If cyberintelligence departments were given names today, they might be called Internet Intelligence, Virtual Intelligence, Data Intelligence or Online Intelligence departments.

This may be due to the fact that government organizations are typically named by middle-aged or senior officials who are generally less likely to be familiar with the current trends in technology language. They are more likely to stick to the words that were used when they first learned about the technology. Such organizations, being bureaucracies, are also unlikely to change their name.

The title text continues the joke by implying the organization learned about the demise of "cyber-" yet failed to process or analyze that data. It is a common problem among intelligence organizations to gather "raw information" (such as photos, or reports from spies) but be unable to make use of it because there wasn't time to process the information into intelligence by determining what it means. This is particularly true for intelligence gathered by or relating to computers, as they can generate data far faster than people can review it. It may also be a reference to the previous comic, which was a link to a survey for xkcd readers.

"Cyberspace" and "{{w|cybernetics}}", illustrated [https://books.google.com/ngrams/graph?content=cyberspace%2Ccybernetics&year_start=1990&year_end=2008&corpus=15&smoothing=0&direct_url=t1%3B%2Ccyberspace%3B%2Cc0%3B.t1%3B%2Ccybernetics%3B%2Cc0 here], are two of the most common words with that prefix (Cyberspace 6 times as prevalent as cybernetics at their peaks). "Cyberintelligence" is shown [https://books.google.com/ngrams/graph?content=cyberintelligence&year_start=1990&year_end=2008&corpus=15&smoothing=0 here]. Cyberspace was used 4000 times more often, although the more common spelling splitting it in two words "Cyber intelligence" was 1.35 times more [https://books.google.com/ngrams/graph?content=cyber+intelligence&year_start=1990&year_end=2008&corpus=15&smoothing=0 used] than in one word. But even combining these two versions cyberspace is still used more than 1700 times as often.

==Transcript==
:[Ponytail, pointing at a chart to her left, with text and two curves on a graph, is talking to someone off-screen to the right.]
:Ponytail: Our overall FY2015 cyberintelligence budget was $8.1 billion-
:Off-screen voice: -Yet it wasn't enough to pick up on the fact that no one else has used the prefix "cyber-" for like a decade?
:Ponytail: Shut up.

{{comic discussion}}
[[Category:Comics featuring Ponytail]]
[[Category:Computers]]
[[Category:Internet]]
[[Category:Line graphs]]