Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

May 25

Is aabec real?

Today I read _The Diary of Adrian Mole, Age 13 3/4_, and got to the part where Adrian is learning words from a dictionary. Adrian writes, for his first new word, aabec: "How interesting it is that Aabec should be an Australian bark used for making sweat." This word appears in some old dictionaries, including one Australian English compendium, but is there any real surviving evidence that the bark and the word were ever really used in Australia, or is this just a ghost word like "esquivalience"? If aabec is real, which species of Australian tree does it come from? ~2026-31003-95 (talk) 00:33, 25 May 2026 (UTC)

Well the word is not in the Australian Collins or Macquarie dictionary. The first word is "a" but I suppose that was not new. "aabec" does appear to be used eg see https://trove.nla.gov.au/newspaper/article/157910185?searchTerm=aabec . But I also see misscans of "aspect", "ashes", "aches". Here it is used to get the first position in the column, and a second entry under EXPLANATION: https://trove.nla.gov.au/newspaper/article/110874422?searchTerm=aabec . Trove is a good place to look up old Australian references. Graeme Bartlett (talk) 09:58, 25 May 2026 (UTC)

John Shaw Billings thought so: In 1876 what Billings called a “Specimen Fasciculus’ was printed. It was a momentous event—the beginning of an era in medicine. ... This volume was but seventy-two pages and began with AABEC, a bush as useless as its name would suggest — how mysterious. In fact here's that Specimen Fasciculus, where the entry in full is AABEC. See Morton (M. K.) Aabec bush. Med. and Surg. Reporter, Phila., 1875, xxxii, p. 425. (That's the thing Lambiam found, below.)  Card Zero  (talk) 11:16, 25 May 2026 (UTC)

Here, a 19th-century lexicographer, lamenting his ignorance of words contributed by Australian informers, writes:

For instance—
    “Aabec. An Australian medicinal bark said to promote perspiration.”
I have never heard of it, and my ignorance is shared by the greatest Australian botanist, the Baron von Müller.

There are plenty of (mainly 19th-century) mentions, but here are actual uses:

I refer to an alcoholic extract of an Australian bark, called the Aabec bush. ... As the captain has no interest in the value of this bark to the profession, any further than the scientific interest any educated person would naturally feel, there are considerable hopes felt in the efficacy of Aabec.

 ​‑‑Lambiam 12:14, 25 May 2026 (UTC)

Also:

NEW DIAPHORETIC. This is the Aabec bark, and is used in the form of fl. ext. or infusion. Of the fluid extract a teaspoonful is given every hour. It is under trial.

The Medical Record: Volume X (p. 536). New York, July 31, 1875.

Alansplodge (talk) 21:31, 27 May 2026 (UTC)

A search of Australian newspapers reveals only "Dragoman's Quiz" (syndicated in several newspapers)

Aabec is an Australian bark used medically to produce: (choose one) Blue blood; sweat; delirium; convulsions.|Dragomans Quiz

and a sterling effort in 1977 by a Canberra locksmith to have his advertisement "first in this book". Doug butler (talk) 22:46, 27 May 2026 (UTC)

I've found a few tradesmen and small companies calling themselves Aabec in old British newspaper adverts, presumably to get near the top of the Yellow Pages listing. And of course there was Aabec in Antrim County, Michigan. DuncanHill (talk) 23:03, 27 May 2026 (UTC)

Pepper mills and microplastics

Supermarkets sell bottles of pepper corns with caps that contain a grinder. The grinder is made of plastic. I worry this can introduce microplastics into our food. Has any scientific research been done on this subject? Thank you. Hevesli (talk) 22:50, 25 May 2026 (UTC)

It will, and people increasingly believe it will harm health. Stanleykswong (talk) 23:03, 25 May 2026 (UTC)

I found one scientific paper and a couple of blogs that are most likely correct:

• Investigating microplastic release from plastic grinder heads during salt grinding
• How FDA-Compliant Pepper Grinders Enhance Tabletop Experience in US Restaurants
• Are Disposable Salt and Pepper Grinders Bad? The Hidden Costs of Convenience

If anyone finds more or better sources, please post them. --Guy Macon (talk) 23:31, 25 May 2026 (UTC)

Zbucki, Ł. and Plażuk, E., 2024. Mechanical grinding of spices in grinders with polymeric burrs and transfer of microplastics to food. Health Problems of Civilization, 18(3), pp.339-353. Available at: https://bibliotekanauki.pl/articles/55790756.pdf

Yang C, Li K, Gowen A, Xu JL. Investigating microplastic release from plastic grinder heads during salt grinding. Sci Total Environ. 2026 Mar 15;1021:181608. doi: 10.1016/j.scitotenv.2026.181608. Epub 2026 Feb 24. PMID: 41740354. Available at: https://pubmed.ncbi.nlm.nih.gov/41740354/

Schymanski D, Humpf HU, Fürst P. Determination of particle abrasion through milling with five different salt grinders - a preliminary study by micro-Raman spectroscopy with efforts towards improved quality control of the analytical methods. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2020 Aug;37(8):1238-1252. https://doi.org/10.1080/19440049.2020.1748724. Epub 2020 May 19. PMID: 32428414. Available at: https://pubmed.ncbi.nlm.nih.gov/32428414/

Yinai Liu, Yu Cao, Huiqi Li, Huanpeng Liu, Liuliu Bi, Qianqian Chen, Renyi Peng, A systematic review of microplastics emissions in kitchens: Understanding the links with diseases in daily life, Environment International, Volume 188, 2024, 108740, ISSN 0160-4120, https://doi.org/10.1016/j.envint.2024.108740. Available at: https://www.sciencedirect.com/science/article/pii/S016041202400326X Stanleykswong (talk) 07:24, 26 May 2026 (UTC)

May 26

Heat armoured car heist

In the movie Heat, after an armoured car is knocked over by a semi truck, the thieves need to force it open. As the armoured truck was already lying on its side, would another semi travelling at full speed along the armoured truck's route and ramming just the armoured truck's windscreen and roof hypothetically suffice to shear the entire roof off, thus not needing any tools? cmɢʟee τaʟκ (please add {{ping|cmglee}} to your reply) 19:50, 26 May 2026 (UTC)

A sequel film Heat 2 has a 77-day shoot planned in Los Angeles this year. The production company might appreciate your idea. ~2026-21660-55 (talk) 21:57, 26 May 2026 (UTC)

There are plenty of videos of trucks hitting a low underpass, resulting in the roof being sheared off, so this is within the realm of physical plausibility, probably enough for the suspension of the whole scene also to enable suspension of disbelief. To assist in maintaining belief, the side of the semi in the scenario hitting the overturned truck should be reinforced in advance of the operation; otherwise it would just be sheared off itself first. The semi should also have sufficient momentum to shear off a substantive amount of the roof before the force gets too low, so it must be loaded up with heavy stuff, and the semi must accelerate in advance to reach top speed in time. (It is more believable if the semi decelerates and halts during the operation, before the whole roof is opened up.) The initial impact with the windscreen will tend to deflect the trajectory of the semi, so considerable skill of the driver is required to hit at just the right spot and the right angle, and to keep the semi on track, parallel to the roof, during the actual shearing. Finally a word of caution: do not try this in reality, kids.  ​‑‑Lambiam 09:16, 27 May 2026 (UTC)

Normal cargo trucks have very thin, unreinforced roofs, which is why they peel off so easily in low-bridge strikes. An armored vehicle would likely have a much stronger, reinforced roof, but that roof is designed to resist bullets and blasts, not sideways shearing from hitting a rigid bridge. In that kind of impact, the armor plate itself might stay mostly intact, but the mounting points, welds, or supporting structure could fail. So it’s feasible that a heavily armored roof would be torn off more as a single solid unit than crumpled, even though the vehicle as a whole would still be severely damaged. ~2026-16820-81 (talk) 11:21, 27 May 2026 (UTC)

I feel we also have to consider what happens to the semi. Lambian has touched on this but are we sure it will stay upright and actually be able to travel past the armoured truck? If it doesn't it might simply end up blocking the shear-off hole. The point about the driver is another interesting one. Frankly you'd need someone either real crazy or terminal to be willing to be the driver IMO. Nil Einne (talk) 15:16, 27 May 2026 (UTC)

AI drives all the cars because why not? AI drives the armored truck. AI drives the semi. Waymo vs Tesla star in "Waymo Money." The problem is it turns out that all the money was in virtual coins and the armored truck was just carrying encrypted thumb drives. ~2026-16820-81 (talk) 16:41, 27 May 2026 (UTC)

It would be very hard for the thieves to plan this. It's almost impossible to predict the exact orientation in which the armoured truck comes to rest after it's knocked over, as this depends chaotically on its position, velocity, rotational inertia, the impact point et cetera. Hitting the armoured truck with another vehicle at the right angle to tear off the roof might proof difficult if it's inconveniently oriented. PiusImpavidus (talk) 17:05, 27 May 2026 (UTC)

In other words, because this is an action movie script we are talking about, surprisingly easy. Barely an inconvenience. :) --Guy Macon (talk) 23:32, 27 May 2026 (UTC)

@Cmglee: So maybe, or no, or yes.  ​‑‑Lambiam 06:26, 29 May 2026 (UTC)

The average action movie is obviously a documentary. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:25, 29 May 2026 (UTC)

Thanks, everyone. Great points about the unpredictability of how the truck lands, and the semi blocking the gap. I'd better not try it at home then :-D cmɢʟee τaʟκ (please add {{ping|cmglee}} to your reply) 20:03, 1 June 2026 (UTC)

Four out of five armored car robbers recommend you chew sugarless gum instead. Clarityfiend (talk) 06:11, 4 June 2026 (UTC)

May 30

What about the application of the Solomonoff induction to the person to person information exchange?

No information is being asked for. Instead, we are being asked to respond to nonsensical and almost incomprehensible posts based on spurious assumptions. Such discussions do not belong here, or anywhere else on Wikipedia, according to long-established Wikipedia policies. Closing per WP:NOTFORUM The following discussion has been closed. Please do not modify it.

It seems it adds some principial boottleneck to the human to human communications. You have to guess what the other person mean.

More details here in russian: https://transitional-writes.dreamwidth.org/41031.html It seems it is proof of the famous Mises calculation argument theorem. The only mean to circumvent this bottleneck is to use physically preserve money like gold, uran, platinum.

Can we discuss this topic at least? It is totally related to the natural science methodology. ~2026-32197-56 (talk) 10:12, 30 May 2026 (UTC)

Mises calculation argument: Economic calculation problem

Solomonoff induction: Solomonoff's theory of inductive inference

human to human communications: Human communication

Google Translate of Russian source:

Well, yes—Galois theory applied to state governance. If we set aside decentralized governance—the kind based on a currency whose value is preserved by the laws of physics: gold, platinum, uranium—

It becomes a special case of Mises's theorem applied to a vertical structure. "The Battle for the Bloody Bridge"—that, I believe, is how the Anglo-Saxons described it, drawing on their experience in the Anglo-Boer War. Then all that remains is the vertical hierarchy of power.

1. Kolmogorov complexity and *a priori* triangles used to compress a bitstream representing *N* actions with parameters X, Y, and Z (something like this: [website: research.swtch.com/zip]. Whether for a lieutenant or for Comrade Stalin, this complexity is bounded—and roughly equal.

2. Moving vertically upward through the hierarchy, a game of "telephone" ensues due to the inherent difficulty in interpreting signals—a difficulty stemming from [wikipedia: Solomonoff's theory of inductive inference]

3. Ultimately, everything hinges on the actions of the lieutenants—those who understand the specific local conditions — and on the actions of Comrade Stalin, who knows nothing of the specific local parameters, yet possesses knowledge of fundamental *a priori* principles. Or perhaps he does not. The intermediate links in the chain are merely gambling at the casino.

The author appears to not understand currency, economics, information theory, or human communication. Decentralized governance has very little overlap with currency. Ancient China had an extremely centralized government and used copper coins as the main currency, to take one example. See Metallism and Fiat money.

The author also appears to be using Solomonoff's theory and Galois theory as hand waving -- claiming that his political and economic claims are based upon those theories without explain how. --Guy Macon (talk) 13:00, 30 May 2026 (UTC)

Thank you for you answer.

Could we discuss this topic step by step?

1. First question is the inductive bottleneck in the human to human communications caused by the

properties of the inductive inference and perception per se.

See https://en.wikipedia.org/wiki/Solomonoff%27s_theory_of_inductive_inference

If we apply this theory to the "bitstream" that is seen by the peers in the human communccation

we can infer that there is fundamental uncertainty that we get all information right from the peer.

2. The second question is the application of the first step to the problem of the economic calculation.

If we can not trust peers we have to use something that we can trust.

Some primitives of the decentralized control that could be trust like gold. ~2026-32197-56 (talk) 13:15, 30 May 2026 (UTC)

No, the first question is the variation if the frequency of a cat's purr caused by the diamagnetic properties of subduction zones on the sea floor. Then we can apply this theory to the melting point of candlewax as the first step to the Birch and Swinnerton-Dyer conjecture as it relates to Cockcroft–Walton generators.

You can pick your unrelated subjects that you try to tie together with no explanation as to why you think they are related, and I will pick mine. --Guy Macon (talk) 15:04, 30 May 2026 (UTC)

[NB: Also posted on the Mathematics Reference desk. {The poster formerly known as 87.81.230.195} ~2026-27434-43 (talk) 14:42, 30 May 2026 (UTC)]

That will be fun to watch. I will make popcorn. --Guy Macon (talk) 15:04, 30 May 2026 (UTC)

This is a reference desk. And given that no reliable source is likely to have ever discussed 'the application of the Solomonoff induction to the person to person information exchange', we aren't going to be able to give any response appropriate to a reference desk, rather than a forum. This is not a forum. AndyTheGrump (talk) 15:34, 30 May 2026 (UTC)

But anyway. It seems this is totally correct question.

There is no obstacles to discuss this topic.

And there is no obstacles to apply the results to other problems like economic calculation argument.

So we see open and correct scientific topic.

What can we do with that?

Assuming this is one of the most important problems for the humanity. ~2026-32028-60 (talk) 15:46, 30 May 2026 (UTC)

No, we are under no obligation to assume that this is 'one of the most important problems for the humanity'. Or even that it is a rational question at all, given that it has been posted by someone who seems to think (amongst other things) that 'value' is a physical property of matter, rather than a social construct. If you want to engage in facile debate about gibberish, you will have to find somewhere else to do it. AndyTheGrump (talk) 15:51, 30 May 2026 (UTC)

Please see the box at the top of this page. A reference desk just looks up things in a library and tries to point you to a suitable reference if they can find one. It doesn't engage in opinions or predictions or debates or original research about even the most important problems for humanity. Perhaps X or Reddit do that, I've never used them but I hear they host lots of debates. NadVolum (talk) 16:28, 30 May 2026 (UTC)

Just to defend myself: at least everyone knows now that this question wasn't discussed anywhere.

How can I get this information without the question to the reference desk?

So my question is justified.

Also I think the wikipedia Talk page may be the correct place to discuss such things.

Even it is the original research it may lead to the formally acceptable outcome.

https://en.wikipedia.org/wiki/Talk:Solomonoff%27s_theory_of_inductive_inference ~2026-32028-60 (talk) 16:33, 30 May 2026 (UTC)

June 3

Biology behind Teenage Brain Development

For this reasoning, why does the teenager's brain function differently, than the adult brains, and what is behind the biology and psychology? I remember on the example on how the teenager's brain process differently.

For these extra hints, I have learned some information in 2019. According to this books, named "How Psychology Works: The Facts Visually Explained" by DK, explain the concepts and the reasoning of the psychology. In page 22-23, the scanage has revealed that adolescent brains process to utilize information differently than adult brains, and "These differences help to offer a biological explanation for why teenagers can be impulsive, sometimes lack good judgement, and can become overly anxious in social situations." in "What is it?" section. Of course, there are some different approaches about what the body and biological process shape human behavior, and what is determined by individual genetics in some specific areas. I would like to go more in-depth about the evolutionary psychology, including natural selection, individual differences, information processing, and psychological adaptations.

Link to this Book:

• https://dk.com/en-us/products/9781465468611-how-psychology-works

• https://www.goodreads.com/book/show/36747292-how-psychology-works

• https://www.penguinrandomhouse.com/books/600739/how-psychology-works-by-dk/

~2026-33106-46 (talk) 22:02, 3 June 2026 (UTC)

Already at a young age, there is a large variation among children of the same age in how impulsively they act and how risk-averse they are. While adults tend to exercise more self-control than their younger selves, it is methodologically very difficult to determine how much of this is due to greater physiological maturity of the brain and how much can be ascribed to having learned more about the potential consequences of one's actions, whether through actual experience or through reflection.

Myelination of the brain commences before birth and progresses well into adulthood; see Timeline of human brain development. The regions of the prefrontal cortex are the last in which this maturation process reaches its completion. Since this brain region is involved in a wide range of higher-order cognitive functions, including risk processing, and its basic activity is considered to be the orchestration of thoughts and actions in accordance with internal goals, it is plausible that this plays a role in observed age-related behavioural differences. But, as said, the extent to which this physiological aspect explains these differences is very hard to assess.  ​‑‑Lambiam 05:43, 4 June 2026 (UTC)

A lot of synaptic pruning happens during adolescence. I wonder how that impacts brain function. Sean.hoyland (talk) 07:54, 4 June 2026 (UTC)

Youth often behave as if they think they're immortal. That's been true forever. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:04, 4 June 2026 (UTC)

@Baseball Bugs @Lambiam @Sean.hoyland How could this be definitely true forever? I could learn this in a book. ~2026-33106-46 (talk) 22:33, 4 June 2026 (UTC)

References

June 5

Cheap vacuum pump

Can a thing like that be any good? Purpose is evacuating those compression storage bags (plastic bag that you put around pillows and stuff to make them smaller), and similarly with a foam insulated camping pad. I tried a vacuum cleaner and that doesn't generate nearly enough vacuum. But other vac pumps e.g. at Harbor Freight cost a lot more. This would be for occasional use so I'm not too worried about durability as long as it basically works. Also it says 28.3" Hg which is about 0.94 atmosphere (i.e. all but 0.06 atm is removed). That should be plenty for the purpose, right? thx. ~2026-33254-93 (talk) 04:31, 5 June 2026 (UTC)

That pump appears to be air driven. That means you need a decent compressed-air source to drive it. An Amazon search for what you are trying to do, for low cost, gave me lots of cheap electric and hand-operated options: . DMacks (talk) 04:42, 5 June 2026 (UTC)

Thanks and good catch on the compressed air, I better look omre closely. But the devices you linked to say things like "6000 Pa vacuum" which is like 1 psi, comparable to a vacuum cleaner, and I found that using a hand vac (dustbuster style) didn't generate anywhere near enough suction. I guess I could consider a web-dry shop vac as those claim around 40 inches of water lift which is around 2 psi. But I would have thought I needed actual vacuum (say 90% rather than 10%) to really compress the stuff in the bag. I'll try some more tests I guess. (This is OP). ~2026-33680-75 (talk) 20:02, 6 June 2026 (UTC)

I recently used an Amazon-purchased bag+pump combination to reduce the volume of goods (mainly clothes). The electric pump was definitely cheap in price and construction, but managed a satisfactory result in turning a floppy bag into a fairly rigid item that could be stacked on edge without collapsing. But the thing is, this doesn't require a vacuum. All it is doing is removing the air from the bag, assisted by normal atmospheric pressure on the outside. Most of the work is done by the valve, which stops any air removed from returning. All the pump has to do is lower the pressure outside the valve to slightly less than the pressure inside the valve, which (given the bag is not a rigid container) continues to be atmospheric pressure. The result is not a vacuum, but a bag with very little air between the other contents. What that pump could not possibly do is reduce the pressure within a rigid vessel to anywhere close to a vacuum. -- Verbarson  ^talk_edits 21:28, 6 June 2026 (UTC)

When compressing things like clothes. pillows, goosedown items, etc., the limit is when the item pushes back as hard as the plastic is pushing in. Things like folded canvas pretty much resist further squeezing no matter how hard you squeeze them. Foam pillows, on the other hand, keep getting smaller as you add more force.

Another gotcha is this: sometimes "2 psi of vacuum" means "2 PSI away from 0 PSI" and other times it means "2 PSI away from 14.7 PSI". Vacuum pumps and vaccuum cleaners are especially likely to use different definitions. An engineer would say "2 PSI absolute" or "2 PSI delta".

Your best bet to get the lowest absolute pressure in the bag at a reasonable cost is a sous vide pump ( https://www.amazon.com/s?k=sous+vide+pump&s=price-asc-rank ) but be aware that if it is a hand pump you are going to do a lot of pumping and if it is electric it may be slow and you may have to stop partway through to let the pump cool down. --Guy Macon (talk) 21:53, 6 June 2026 (UTC)