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

October 1

Are dyslexia and nonverbal atavisms, and why do/don't they count as such?

Around a year or two ago, I discovered the term "atavism" – the state in which a trait (e.g. a tail or hind limbs) that have been lost through evolutionary pressures reappear in an individual. This made me wonder – can the two aforementioned disabilities count? Goats 601 (talk) 20:29, 1 October 2026 (UTC)

This is a popular pop science topic. Not to say that its wrong. Rick Riordan made Percy Jackson have ADHD and dyslexia for the benefit of his son's self-esteem, and suggested that these are traits and that they would have been adaptive in the past. There is this hypothesis of self-domestication in humans. Certain issues come to mind; there is basically no genetics for these disorders, and natural selection in humans is incredibly weak in general, and in particular for behaviors. The whole field of evolutionary psychology is a scam and a joke. But don't rule out the possibility that some disorders might be atavistic. Just be unbiased. Abductive (reasoning) 00:09, 2 October 2026 (UTC)

October 4

The purple slime of twelve thousand snails

Tyrian purple#Production from sea snails has the quote "twelve thousand snails of Murex brandaris yield no more than 1.4 grams (22 grains) of pure dye, enough to colour only the trim of a single garment", from I think fr:David Jacoby, a historian. I just edited this to include the source's source, Paul Friedländer (chemist). But something smells fishy. This 1925 Introduction To Organic Research speaks of Friedlander's isolation of 1.5 grams of 6,6'-dibromindigo. I am not worried about where the 0.1 gram went missing, but I wonder how Jacoby concluded that this was "enough to colour only the trim". Is it possible that Friedlander's experiment was not representative of an efficient industrial method of harvesting dye, but was in fact quite destructive in the course of seeking purity? Furthermore, might the very pure dye that resulted have been powerful enough to dye a whole lot of cloth? The legend of the discovery of purple is that a dog bit a snail and got a purple mouth - from chewing on one snail, not several thousand.  Card Zero  (talk) ※ 00:34, 4 October 2026 (UTC)

This Worst Jobs in History video says 1,000 shells for one whole cloak. The process is demonstrated for real. Taste-testing fermenting snail goo. Eww. Abductive (reasoning) 19:41, 5 October 2026 (UTC)

October 6

Artificial stomachs

Will science ever be able to produce an artificial stomach just like it has been able to produce an artificial heart? Especially only using machinery? Or is that impossible, with one needing actual enzymes to properly digest food, which machinery can never, ever replicate? ~2026-53159-81 (talk) 02:22, 6 October 2026 (UTC)

We don't answer requests for predictions. Note that current artificial hearts can only temporarily stand in for natural hearts. Note also that the power source of current artificial hearts is an internal battery that needs to be recharged from an external power source. There is no reason to think developing a fully functional artificial replacement is impossible in principle. But it will be incredibly difficult.  ​‑‑Lambiam 03:51, 6 October 2026 (UTC)

Enzymes can be synthesized, no? —Antonissimo (talk) 04:11, 7 October 2026 (UTC)

Important enzymes needed for breaking down the nutrients and allowing them to be absorbed are pepsin and intrinsic factor. They could be produced by genetically modified bacteria, which may be more doable than synthesizing them in a portable miniature laboratory.

There is a US patent for an artificial stomach, using which these enzymes would need to be supplied externally ("a chemical food handling system may be adapted to release various chemicals into the food reservoir for treating the food, e.g. by releasing digestion-facilitating chemicals (e.g. an enzyme, an acid, etc.) ... Furthermore, an injection port connected to the special container is also provided to enable filling or re-filling of chemicals to the special container."). I don't think embodiments of this or similar inventions have been tested on actual patients.

Within the scope of futuristic scenarios, having patients regrow biological stomachs may be more promising than developing functional artificial ones.  ​‑‑Lambiam 07:48, 7 October 2026 (UTC)

That's my point, though! You'd need to supply biological enzymes externally, not produce enzymes made from machine parts. ~2026-53159-81 (talk) 23:16, 7 October 2026 (UTC)

Artificial digestion is related to what you're asking about, and its references might lead you further, if the references have enough references once you track them down.Rich (talk) 00:47, 10 October 2026 (UTC)

illicit antidepressants

News reports that Sean "Diddy" Combs has been getting illicit goodies in prison, including Hennesey's liquor, cellular phones, and Remeron (Mirtazapine). I can understand the prison being upset about the first two, but the last is a tricyclic antidepressant with annoying side effects. It doesn't sound like a recreational drug. If it's helping him (prison has to be conducive to mental health issues) shouldn't he be able to get a prescription? Or is this actually a drug that people take for fun? The article doesn't say anything about abuse potential and it's not the type of thing I'd expect drug dealers to have on offer. Thanks. ~2026-53423-74 (talk) 07:37, 6 October 2026 (UTC):

<- LLM-generated reply removed. Wikipedia does not permit the use of Chatbots on talk pages -> AndyTheGrump (talk) 17:51, 6 October 2026 (UTC)

Heidi Krauth CEO of Audria recently announced a AI startup serving dementia patients .Is the above post from the same AI ? ~2026-39925-22 (talk) 16:43, 6 October 2026 (UTC)

 Courtesy link:  doi:10.1080/10550887.2025.2514287, doi:10.1371/journal.pone.0340092 and doi:10.1001/jamapsychiatry.2026.0159 all seem to be genuine, so we just need to teach the AI to create links.... Mike Turnbull (talk) 17:25, 6 October 2026 (UTC)

Thanks but those links are about using mirtazapine to treat drug withdrawal and about its safety profile, i.e. useless from the perspective of the original question, which was about abuse potential. I also wonder how Diddy managed to pay for stuff while in prison. ~2026-53423-74 (talk) 19:47, 6 October 2026 (UTC)

Presumably he has friends, employees, etc., on the outside who are willing to pay for things on his behalf? His being in a low-security correctional institution may also have some bearing on what he is allowed to receive from outside. {The poster formerly known as 87.81.230.195} ~2026-41275-62 (talk) 06:51, 7 October 2026 (UTC)

"Despite its potential benefits, mirtazapine can be addictive and lead to abuse, mainly when it is used recreationally."  ​‑‑Lambiam 07:54, 7 October 2026 (UTC)

October 7

What is the evolutionary reason behind the somatosensory cortex for the genitals and feet neighbouring each other? What clade is this a synapomorphy of?

Ditto, but I learned this is one of the main reasons for the evolution behind the prevalence of foot kinks. Goats 601 (talk) 11:34, 7 October 2026 (UTC)

Perhaps it was purely accidental. After all, the regions involved had to neighbour some area. What is the reason a lowercase h looks like a horse? More seriously, why are the regions of the cortex involved in the identification of letters and numbers adjacent to a region involved in colour-processing? (See Synesthesia § Mechanism.) I doubt this has an evolutionary reason.  ​‑‑Lambiam 16:37, 7 October 2026 (UTC)

All are innervated from the Sacral plexus. Abductive (reasoning) 08:21, 8 October 2026 (UTC)

And what's the evolutionary reason for the pelvis and feet belonging to the same nerve plexus?

Furthermore, why are the genital and pelvis sensory nerves not in the same plexus? Goats 601 (talk) 11:38, 8 October 2026 (UTC)

You asked what clade. It's Vertebrata or Chordata, which are characterized by having a spinal cord, or a tail. The wiring is adjacent, the brain regions are adjacent. Abductive (reasoning) 18:29, 8 October 2026 (UTC)

You remind me of a book of my childhood, in which h was a lady with a bustle. —Antonissimo (talk) 05:04, 8 October 2026 (UTC)

Holy Toledo. How old are you? :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:24, 8 October 2026 (UTC)

Older than I look (it seems), but not nearly old enough to have seen bustles in real life! —Antonissimo (talk) 19:02, 8 October 2026 (UTC)

October 8

flag of Mars

I was wondering whether a cloth flag would even be able to get up a decent flutter in the thin atmosphere of Mars. (I tried to calculate it myself before but gave up.) — Arlo James Barnes (pro-∪nion) 21:06, 8 October 2026 (UTC)

There are windstorms on Mars from time to time. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:22, 8 October 2026 (UTC)

True, and some of them seem persistent: — Arlo James Barnes (pro-∪nion) 21:50, 9 October 2026 (UTC)

You might be interested in Lunar Flag Assembly - no wind but it looked good anyway being a bit like a curtain rather than stretched and flat. I guess one could stick usa a motor but that would be extra weight. NadVolum (talk) 22:20, 8 October 2026 (UTC)

Calculations by Google AI (not Wiki-Reliable and possibly wrong) indicate that the Wind Power Density (a common measure of "wind power") at the Martian surface can rise as high as 911 Watts per square metre (in a dust/wind storm), while the average WPD required to make a flag flutter is 25–75 Watts per square metre.

It therefore appears that a flag would, some of the time, flutter satisfactorily on Mars, though intuition suggests to me that the flutter would be slower than typical on Earth (am I wrong?). Using the lightest possible flag fabric would obviously help. {The poster formerly known as 87.81.230.195} ~2026-41275-62 (talk) 07:52, 9 October 2026 (UTC)

More important than wind speed is the low (~1% of Earth) density of the atmosphere. There is very little air pressure to move a flag. --mikeu ^talk 17:37, 9 October 2026 (UTC)

The value quoted is wind power density, not wind speed.  ​‑‑Lambiam 02:22, 11 October 2026 (UTC)

References

The start of crossdressing

An unbreeched 2-year-old FDR in 1884 is NOT what I'm asking about here!

Is there any data as to what percentage of crossdressers (transvestites) begin crossdressing in which stages of their life (early childhood, onset of puberty, late adolescence, early adulthood, mid-adulthood, late adulthood, old age, et cetera)? ~2026-53159-81 (talk) 22:39, 8 October 2026 (UTC)

It may have started with Jefferson Davis. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:50, 8 October 2026 (UTC)

I don't see any mention of him crossdressing on his article! ~2026-53159-81 (talk) 23:06, 8 October 2026 (UTC)

Read it more closely. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:42, 9 October 2026 (UTC)

If any such data exists, it can only do so in relation to a specific society and time period. What might be considered 'crossdressing' could only be answered in relation to social norms: and in many societies, young children were dressed identically regardless of assigned gender anyway. See e.g. Breeching (boys). AndyTheGrump (talk) 23:00, 8 October 2026 (UTC)

I meant voluntary crossdressing, not little boys wearing dresses because their parents forced them to, as was actually historically a thing in the West with unbreeched boys. ~2026-53159-81 (talk) 23:06, 8 October 2026 (UTC)

Boys were no more 'forced to wear dresses' than girls were, in societies where dresses for boys were the norm. Nobody is born with a need to wear a particular item of clothing. In as much as 'transvestism' means anything at all, beyond being a pseudomedical label, it can only describe a desire to wear clothing considered gender-inappropriate in one's own society. AndyTheGrump (talk) 23:43, 8 October 2026 (UTC)

There is a bunch of data on this from the late 1900s. Their data and analysis are very flawed, so I would take it several heavy handfuls of salt, but Karl Freund and Ray Blanchard both developed scales that asked questions like this. I believe Jaimie Veale has done some more rigorous research using some of these scales, but her research focuses on transgender people, not crossdressers. Katzrockso (talk) 03:54, 9 October 2026 (UTC)

Children dressing up without being 'forced' is very common indeed! What the question seems to be asking is about people who later identify as transvestites and who see the clothes as part of their identity. My guess is there wouldn't be much difference between that and when people start identifying as transvestites in the first place. NadVolum (talk) 09:45, 9 October 2026 (UTC)

Some transvestites, such as F1NN5TER (who now identifies as genderfluid), begin crossdressing later in life, so I was wondering just how frequent this vs. an early start to crossdressing was. ~2026-53159-81 (talk) 19:29, 9 October 2026 (UTC)

Cross dressing was mandatory in Elizabethan theater where, for example Juliet in Shakespeare's Romeo and Juliet (1597) would have to be acted by a boy. The image shows the confusion arising in the parody comedy Shakespeare in Love where the anachronistically actual female Juliet is played convincingly by Gwyneth Paltrow. ~2026-39925-22 (talk) 22:39, 10 October 2026 (UTC)

Amyloidosis and extreme longevity

Not a forum The following discussion has been closed. Please do not modify it.

Will curing amyloidosis allow many more centenarians and supercentenarians to reach age 120+? ~2026-53159-81 (talk) 23:08, 8 October 2026 (UTC)

October 9

Dual-role transvestites

Is dual-role transvestite essentially just the historical term for genderfluid people? ~2026-54446-24 (talk) 22:49, 9 October 2026 (UTC)

I would distinguish the two. What 20th century sexologists called dual-role transvestism mostly seems to describe being closeted (as either a cross-dresser or a trans woman) in some parts of one's life, not freely arising fluidity of one's gender.

The ICD-10 diagnosis allegedly referred to cis male crossdressers who sometimes adopted a female persona but had no desire to transition full-time. In practice, the label could be applied to deny gender-affirming treatment to anyone who gatekeeping practitioners deemed sort-of-trans (compared to fetishists) but still not trans enough. –RoxySaunders 🏳️‍⚧️ (talk • stalk) 04:24, 10 October 2026 (UTC)

October 11

rationalization of electromagnetic systems

Dear sirs, please excuse my poor english. I would desire on-line references to two sentences about the rationalization of the electromagnetic systems.

I have recovered an old diskette (probably written around 1980) with notes on metrology. It is written in italian and what follows is my translation, but for the part in "" of the first sentence that is in english and seems taken verbatim from the source.

--- 1st sentence

Indeed, in 1890 Oliver Heaviside wrote: "the unnatural suppression of 4pi in the formulas of central force, where it has a right to be, drives it in the blood, there to multiply itself, and afterward break out all over the body of the electromagnetic theory" (EB57:17/879).

I guess that EB57:17/879 means Encyclopedia Britannica, 1957 edition, volume 17, page 879.

--- 2nd sentence

In 1902 Fitzgerald said that [dealing with the unrationalized systems then in general use] the only rule is to consider carefully whether 4pi should be in an equation and, after concluding that it should not, put it in (P60:42).

I guess that P60:42 is page 42 of a book written in 1960 by an author whose name starts by P, probably italian.

Thanks ~2026-53216-61 (talk) 10:47, 11 October 2026 (UTC)

The quote can be found in a book by J. R. Partington. However, this book is from 1953 and the page is 677.  ​‑‑Lambiam 22:27, 11 October 2026 (UTC)

Interestingly, the citation given in that text (FitzGerald 1902, Scientific Writings) is dated after FitzGerald's death. (fugues) (talk) 23:58, 11 October 2026 (UTC)

The first quote is from Heaviside's Electromagnetic theory, first published in 1893. It can be found on pp. 121 of this edition on archive.org. The second quote is more challenging. After some research, it seems very likely to have originated in one of the many letters written between Fitzgerald and Heaviside, collated across various collections such as the Royal Dublin Society Digital Archive; however, I can't find a single primary or secondary source with this particular line, nor which directly states that FitzGerald ever challenged Heaviside on his desire to popularise rationalised units for Maxwell's equations. The subject apparently isn't covered in The Maxwellians by Bruce J. Hunt, which seemed to be the most likely possible source given its coverage of said correspondence, but the only copy I have access to is an early preprint and it seems to have been extensively edited since then. (fugues) (talk) 23:53, 11 October 2026 (UTC)

Thanks to all, excellent answers.

So excellent, that I have printed the screen into a pdf. Then I have copied the screen in a file using the mouse to use it in my ASCII files. Finally I have tried the same action with the text appearing in the edit page. But here the mouse does not work. The evidenced text is not recovered inside a terminal. Is this action possible? Thanks again ~2026-53216-61 (talk) 07:26, 12 October 2026 (UTC)