explain xkcd - User contributions [en]

Talk:3087: Pascal's Law

2025-05-10T11:57:01Z

172.68.55.47:

I remember learning about this and thinking it was intuitive, but I didn't really think of these consequences. Maybe everybody is making powerful lifting machines for lifting cars and houses with your bare hands, rather than explaining the article, that there isn't one yet. Pascal's law basically says that if you make one end of a container of fluid X times larger, then any force exerted on the small end is multiplied by X on the large end, so you can make it near-infinite by making the small end very small. But you'll need a little more machinery added (like a gear system) if you want the distance actually moved to be higher. Actually I think that might undo the gains in force entirely. That might be how it happens, it might swap distance for force so the same work is performed.

Hey, remember that comic where Randal challenged people to fold a paper too small? This hand-makeable device could get farther on that!
[[Special:Contributions/172.70.111.110|172.70.111.110]] 21:46, 9 May 2025 (UTC)
: yes, that's how it works; the total work is constant and the hydraulic system is converting a small force over a long distance to a large force over a small distance. if you additionally want the force to be over a larger distance, you need to put more energy into the system or else you could push this machine with its own output and get free energy from nothing. really though hydraulics are just smoother, backlashless, equivalents to a gear train in the first place so you generally wouldnt need to use both. - [[User:Vaedez|Vaedez]] ([[User talk:Vaedez|talk]]) 23:37, 9 May 2025 (UTC)
:: Small tube needs to be X times as long to get same displacement. Good for linear force rather than torque. Fluid's own pressure can be the force if tube is long enough. [[Special:Contributions/172.68.55.33|172.68.55.33]] 11:41, 10 May 2025 (UTC)

As someone old enough to remember the [https://en.m.wikipedia.org/wiki/Slashdot_effect slashdot effect], I wonder if XKCD comics generate a similar effect on search engines. Though I doubt they would buckle under the weight these days. [[Special:Contributions/172.69.60.148|172.69.60.148]] 22:00, 9 May 2025 (UTC)

To whoever wrote the initial transcript, remember that we don't include the title text. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 22:06, 9 May 2025 (UTC)

I have to wonder whether he has the same disbelief of, say, levers... which allow one to move the Earth. [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 23:34, 9 May 2025 (UTC)

Although some laws of physics are absolute and lead to extreme consequences, others are taught in a simplified form that can lead to wrong conclusions. For example, "Light and heavy objects fall at the same rate" can be used to prove that objects fall at the same rate on the Earth and the Moon - which is far from correct. If the Moon were somehow dropped onto the Earth, it would fall at a certain rate. The Earth dropped on the Moon would necessarily fall at the same rate. So if the Moon falling on the Earth fell at the same rate as a bowling ball, then the bowling ball would have to fall at the same rate on the Moon. When I read Heinlein's _The Rolling Stones_ as a pre-teen, where he describes things falling slower on the Moon, I applied this reasoning and concluded that Heinlein must have made a mistake. The solution to this paradox is that something as big as the Moon will not only accelerate toward the Earth, it will significantly accelerate the Earth toward it, so the Moon does not actually fall at the same rate as a bowling ball. [[User:Cphoenix|Cphoenix]] ([[User talk:Cphoenix|talk]]) 01:01, 10 May 2025 (UTC)
: I think if you stand at the shared center of mass of the Earth and Moon, that then you see the Moon falling toward the Earth according to its constant field of gravitational acceleration, as well as the Earth falling toward the Moon according to its constant field of acceleration. It was indeed confusing for me to realize this, involving visit to pages such as https://en.wikipedia.org/wiki/Gravitational_acceleration . F=Gm1m2/r^2 so if m1 is taken out you get a constant F=m1 a2 and vice versa. But I think the page says this only holds if the masses are far enough from each other to be treatable as points. [[Special:Contributions/172.68.55.47|172.68.55.47]] 11:57, 10 May 2025 (UTC)

Besides, isn't it better to just ''believe'' in Pascal's Law if it offers a reward of near-infinite force?
[[User:StapleFreeBatteries|StapleFreeBatteries]] ([[User talk:StapleFreeBatteries|talk]]) 04:58, 10 May 2025 (UTC)

Could this be referencing or inspired by this recent paper talking about the use of hydraulics to build pyramids? https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0306690 [[Special:Contributions/172.68.234.169|172.68.234.169]] 08:52, 10 May 2025 (UTC)

3085: About 20 Pounds

2025-05-08T03:17:16Z

172.68.55.47: Added note in comment about how a 20-pound fundamental particle cannot actually exist - should probably get merged into article.

{{comic
| number = 3085
| date = May 5, 2025
| title = About 20 Pounds
| image = about_20_pounds_2x.png
| imagesize = 666x278px
| noexpand = true
| titletext = In addition to gravity, burritos interact through the strong, weak, and electromagnetic forces, which is believed to be a major contributor to their popularity.
}}

==Explanation==
{{incomplete|Created by a £20 20-LB PARTICLE. In ludicrous units. Are any categories missing? Don't remove this notice too soon.}}

The nature of {{w|dark matter}} is a significant unsolved problem in physics. We observe that galaxies spin faster than we expect based on the nearby observable matter. Likewise galactic motions indicate additional mass that we have not observed in other ways. Dark matter is the name we give to this mass. In the comic, [[Cueball]] and [[Ponytail]] consult an {{w|oracle}} to learn about dark matter.

The pentacle and candles suggest that the oracle is supernatural, summoned by an occult ritual; something which would present its own challenges to our understanding of the physical world. There may be a pun here, in that they may be using 'dark magic' to communicate with something from the 'dark realm' on the assumption that it will know about dark matter. However, the word 'dark' in dark matter simply means that we do not know how to observe it; we have no evidence that dark matter is evil or satanic (though [[Randall]] may consider it [[:Category:Comics with cursed items|cursed]]). The oracle is used very similarly to how people have been using and customizing {{w|large language model|large language models}}.

In general, not all forces interact with all particles; indeed, {{w|gravity}} is believed to be the only force that interacts with everything we have observed. If a force doesn't interact with a particle, then the particle's existence cannot be directly observed via disturbances in that force. In particular, something that doesn't interact with electromagnetism cannot be 'seen', as photons will pass through it relatively unaffected, and likewise cannot be felt, because collision is a side effect of the {{w|Pauli exclusion principle}}.

Even {{w|neutrino}}s — famous for {{what if|73|interacting with ''almost'' nothing}} — still interact via the {{w|weak force}}, allowing them to be detected with sufficiently large tanks of dense material (as most atoms interact with the weak force, however weakly). This is in fact the main reason neutrinos cannot be the dark matter: they interact far too much to be a viable option. A particle that interacts with ''nothing'' except gravity could only be detected by a {{w|LIGO|gravitational telescope}}.

Dark matter is infered from its interaction gravitationally with other matter (the evidence for it is in the relative rates of rotation of galaxies, for which no visible evidence of mass is in evidence). While no other form of interaction has yet been observed, terrestrial dark matter experiments are looking for all possible variations of the 'missing mass' that might be detectable by other means. For example, a popular dark matter candidate is a WIMP, or {{w|weakly interacting massive particle}}, which interacts via the {{w|weak nuclear force}}. Dark matter experiments such as XENON build large tanks of liquid xenon with a gaseous top, keep them extremely dark, and look for some way in which passing particles might interact and produce electroluminescent scintilations. There are good theoretical reasons to expect some interaction (ie, to expect that the oracle in the comic is lying), but there are no sufficiently conclusive results as yet. The most important is the observational fact that dark matter exists (assuming it does) throughout the universe, and would be six times more abundant than baryons (which make up almost all the weight of known matter in the universe). 

There is one dark matter candidate where the only interaction is overhwhelmingly gravitational: black holes formed through collapse in the early Universe. These primordial black holes may not be detectable through any terrestrial experiment. However, even these objects can be found through their lensing effects if they are sufficiently large and common in order to account for the 'missing mass' we are looking for. Black holes of around 10 kg would also (most likely) quickly evaporate through Hawking radiation and are thus not a good dark matter candidate. Black holes of around asteroid mass would be extremely hard to detect and are a good dark matter candidate given current information.

The particle's mass is described vaguely as ''about twenty pounds'' (roughly 10 kilograms), in line with how apparently all-knowing oracles legendarily avoid unambiguous statements. This is an absolutely ludicrous amount of energy for particle physics. Any interaction would have to involve an equally ludicrous amount of other particle mass being in exactly the right place and time, a coincidence that might be so rare that one would not expect it to occur ever in the history of the universe. By comparison, the {{w|top quark}}, the heaviest single particle we have observed, with a mass over a hundred times that of the proton, is around a tenth of a trillionth of a trillionth of a pound.

Under more normal circumstances, we might still hope to observe the properties of the particle via creating it ourselves under controlled laboratory conditions. But again, there is no reasonable way to focus the energy required into a single particle interaction. The {{w|Large Hadron Collider|most powerful particle accelerator in the world}}, for example, peaks at about ten thousand times the mass of the proton — a solid billion times less energy than required — so it's out too.

Despite all this, twenty pounds is also much too ''small'' to be detectable via gravitational interaction — its {{w|Perturbation (astronomy)|influence on the orbits of planets}}, say, or the strength of its {{w|gravitational lensing}} effect, would be entirely negligible. Thus in the scenario posed by the comic, there is no plausible way to observe more about dark matter while on Earth. Even if we did find some such particles naturally occurring, and had instruments that could measure such small gravitational forces, since it would interact only via gravity, the only properties it could have other than mass would be its decay rates from other particles — which, again, would all be essentially nil due to its mass.

The oracle proceeds to break expectations by suggesting that Ponytail and Cueball go out for {{w|burrito}}s, something not considered scientific. When faced with the apparent futility of continuing to try to investigate dark matter, the oracle predicts that going out for burritos is precisely as productive as any other approach — i.e., not at all. It justifies the suggestion by burritos being "pretty" good, again neither exactly quantifying the oracularity, and likely not even giving the optimal idea (for choice of food, or of any other "what now?" diversion that it might give).

The title text observes that burritos interact through all four known {{w|fundamental interactions}}, making burritos popular. The electromagnetic force mediates the chemical reactions leading to a burrito's taste, the strong force keeps atomic nuclei together, and gravity gives burritos heft, all of which are helpful for enjoying them. It's hard to see how the weak force, which takes part in radioactive decay, helps with burrito enjoyment or popularity, but the weak force is responsible for the nuclear fusion that allowed the complex elements of the burrito to exist in the first place.

The previous comic [[3084: Unstoppable Force and Immovable Object]] dealt with particles which do not even interact with gravity.
In [[2035: Dark Matter Candidates]] these 20 lb dark matter particles fit between magic 8 balls and space cows. The squirrels that make up [[2186: Dark Matter]] near the earth must be pretty chunky.

==Transcript==
:[Cueball and Ponytail are standing in front of a pentacle with lit candles at the corners. A black sphere, the oracle, is floating above the middle of the pentacle.]
:Ponytail: Dear oracle,
:Ponytail: What is the nature of dark matter?
:Oracle: It's about 20 pounds.

:[Close up of oracle]
:Off-panel: What?
:Oracle: Dark matter is a particle. It weighs about 20 pounds.
:Oracle: It only interacts through gravity.

:[Same view as first panel]
:Cueball: Only gravity, huh?
:Cueball: So none of our experiments are really going to tell us any more about it, then.
:Oracle: Afraid not.

:[Same view as first and third panels, except Cueball lifted his forearm.]
:Cueball: So what do we do?
:Oracle: You should go out for burritos.
:Ponytail: How will that help?
:Oracle: Well
:Oracle: Burritos are pretty good.

{{comic discussion}}<noinclude>
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Physics]]
[[Category:Cosmology]]
[[Category:Food]]

2998: Ravioli-Shaped Objects

2024-10-15T00:42:08Z

172.68.55.47: /* Explanation */

{{comic
| number = 2998
| date = October 14, 2024
| title = Ravioli-Shaped Objects
| image = ravioli_shaped_objects_2x.png
| imagesize = 608x569px
| noexpand = true
| titletext = It's a real accomplishment to mess up a ravioli recipe badly enough that the resulting incident touches all four quadrants of the NFPA hazard diamond.
}}

==Explanation==
{{incomplete|Created by a BULGING LITHIUM BATTERY THROW PILLOW - Ideally the article would contain grounded explanations of both of the views that bulging lithium batteries are either dangerous or safe. What gas builds up? How would an explosion happen, or why would it not? Please change this comment when editing this page. Do NOT delete this tag too soon.}}
{{w|Ravioli}} are a kind of stuffed pasta comprising a filling enveloped in thin pasta dough, commonly square shaped, and serving as the object of this comic's confusion matrix. This comic compares 4 'ravioli-shaped' objects (square shaped objects with bulging cross-sections due to their filling) with common actions associated with them.

{| class="wikitable" | style="background:#E6C3C3;"
! Ravioli-Shaped Objects
! scope="col"| Eat with a fork
! scope="col"| Rest your head on
! scope="col"| Puncture and slurp
! scope="col"| Install in your phone
|-
! scope="row"| {{w|Ravioli}}
| style="background:#C5E6C3;"|Ravioli pasta would indeed be suitable to be eaten with a fork, as shown.
|Ravioli pasta is not structurally strong enough to support the weight of a human head while reclining and would break and spill its filling over your head and the object one is resting on.
|style="background:#FBF8CE;"|If the ravioli filling is thin enough, one could slurp it out with a straw.
|Phones are not meant to run on raviolis{{citation needed}}. Stuffing a phone with a ravioli would cause it to break as shown, spilling the filling through the phone, which is a terrible idea.
|-
! scope="row"| {{w|Throw Pillow}}
|Throw pillows are made of cloth and are inedible{{citation needed}}, whether one uses a fork or not.
| style="background:#C5E6C3;"|A throw pillow is meant to be used as head support while reclining on furniture.
|Throw pillows do not have liquids inside them. Hence, Cueball finds, to his dismay, that they're empty.
|Throw pillows are significantly bigger than phones and as such can't fit inside them, nor power them.
|-
! scope="row"| {{w|Capri Sun}}
|Eating a Capri Sun, a pouch of sweetened juice, with a fork would most likely simply pierce the pouch and spill the liquid all over Cueball.
|style="background:#FBF8CE;"|A Capri Sun would serve as a waterbed of sorts, and wouldn't be unduly uncomfortable in a pinch. Its still likely that the pouch could rupture however.
|style="background:#C5E6C3;"|Capri Suns are meant to be drunk like this, and are enjoyed by many.
|The Capri Sun shown is surrounded by spilled Capri Sun, implying that the installation punctured the pouch. Needless to say, this would be a terrible item to install in place of a phone battery.
|-
! scope="row"| Bulging {{w|Lithium Battery}}
|Bulging lithium batteries are explosive hazards and should not be punctured lest they explode. Additionally the contents of the battery are toxic if one were to somehow manage to eat the burning bits of the battery.
|A lithium battery is a small, hard object, and a bulging one is no exception. Since the bulging comes from a buildup of heat and gas, it would also be a constant fire hazard, which would not be conducive to relaxation.{{cn}} Lithium battery themed throw pillows, which bulge similarly to such batteries, do exist as a novelty item.
|Similarly to the 'eat with a fork' example, puncturing a bulging lithium battery is a bad idea.
|style="background:#C5E6C3;"|A bulging lithium battery could be installed in a phone, if one is willing to break the phone a bit (like the screen in the comic) to accommodate the bulging of the battery. Also a terrible idea, as operating the lithium battery in this condition may result in the battery [https://www.reading.ac.uk/health-safety-services/fire-safety/lithium-battery-information/i-have-a-swollen-lithium-ion-battery-what-should-i-do catching fire or worse]. More commonly, bulging batteries form inside the phone itself, causing it to bulge outwards. Surprisingly, this square is marked in green rather than red or yellow, as the first thing one should do on noticing bulging of the battery is to uninstall it from the device.
|}

The title text refers to the {{w|NFPA 704}} diagram for hazardous materials, a diamond figure put out by the {{w|National Fire Protection Association}} showing four kinds of fire hazards. A ravioli that touched all four quadrants would be a health hazard, fire hazard, and chemical hazard, and have some other miscellaneous hazard(s).

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

:[A 4x4 grid of squares. The columns are labeled: Eat with a fork, rest your head on, puncture and slurp, install in your phone. The rows are: Ravioli, throw pillow, Capri Sun, bulging lithium battery. Each row has an image of each respective item above the title, with the words “Home Sweet Home” on the throw pillow, and “Fruit” on the Capri Sun.]

:Ravioli, eat with a fork: [green]
::[Cueball sits on a chair in front of a table with a jar of sauce on it. He is eating from a plate from ravioli.]
::Cueball: ''Nom Nom Nom''

:Ravioli, Rest your head on: [red]
::[Cueball is lying down on a couch with ravioli smooshed on his head and the couch. Ravioli bits can be seen on the ground]
::Cueball: Eww.

:Ravioli, puncture and slurp: [yellow]
::[Cueball is slurping from a ravioli through a straw. In front of him is table with two plates, presumably with ravioli on them.]
::''Slurp''

:Ravioli, Install in your phone: [red]
::[A phone is shown with bits of ravioli sticking out and tomato sauce is dripping out.]

:Throw pillow, eat with a fork: [red]
::[Cueball sits on a chair in front of a table with a jar of sauce on it. He is poking with a fork at a throw pillow covered in tomato sauce.]
::''Poke poke''

:Ravioli, rest your head on: [green]
::[Cueball is looking at his phone and is lying on a couch. His head is resting on a throw pillow.]

:Throw pillow, puncture and slurp: [red]
::[Cueball is sucking on a straw that is inserted in a pillow.]
::Cueball: Aw man, this one is empty.

:Throw pillow, install in your phone: [red]
::[A phone is shown on a throw pillow that has the words “Home Sweet Home” partially obscured.]

:Capri Sun, eat with a fork: [red]
::[Cueball sits on a chair in front of a table with a jar of sauce on it. He has stabbed a Capri Sun on a plate and is now splattered with juice.]

:Capri Sun, rest your head on: [yellow]
::[Cueball is looking at his phone and is lying on a couch. His head is resting on a Capri Sun.]
::Cueball: Honestly kind of comfortable.

:Capri Sun, puncture and slurp: [green]
::[Cueball is drinking from a Capri Sun through a straw.]
::''Sluuurp''

:Capri Sun, Install in your phone: [red]
::[A phone is shown to be squishing a Capri Sun. Juice is trickling out.]

:Bulging lithium battery, eat with a fork: [red]
::[An explosion bordered by 4 skull and crossbones.]

:Bulging lithium battery, rest your head on: [red]
::[Cueball is looking at his phone and lying on his couch. His head is resting on a smoldering battery.]
::Cueball: This fire hazard is uncomfortable.

:Bulging lithium battery, puncture and slurp: [red]
::[An explosion bordered by 4 skull and crossbones.]

:Bulging lithium battery, install in your phone: [green]
::[A phone with a bulging back, presumably from the bulging lithium battery. The phone’s screen is cracked in the center.]

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Confusion matrices]]
[[Category:Comics featuring Cueball]]
[[Category:Food]]
[[Category:Phones]]