Wikipedia:Reference desk/Archives/Science/2022 October 8

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October 8

Transgender children and suicide

It seems that transgender identity has risen sharply among minors in recent years. It has been argued by many that this huge increase is a result of the notion that this many trans people have always existed but they simply were not comfortable coming out as trans in the past. Transgender advocates and many medical professionals have also argued that if transgender children do not receive gender affirming care such as surgeries, hormone therapy, and puberty blocker, they will end up committing suicide. However, gender affirming care is relatively new meaning there were million of unaffirmed trans kids for decades and centuries before this. Is there any evidence that there was an epidemic of suicide across the world due to lack of affirmation? StellarHalo (talk) 02:46, 8 October 2022 (UTC)

You can take a look at this report: https://williamsinstitute.law.ucla.edu/wp-content/uploads/Suicidality-Transgender-Sep-2019.pdf "Suicide Thoughts and Attempts Among Transgender Adults" but this is not about children. 19.9% rate of attempted suicide per year, but this will be in those that have identified as trans. The report has far more detail on things that affect that rate. Graeme Bartlett (talk) 06:27, 8 October 2022 (UTC)

Nit: 19.9% is of the subset who are in "poor general health", which does not seem to mean "lack of affirmation". The overall rate reported in that study is "only" 7.3% in the year. The "Unique Risk Factors" summary starting on page 2 indeed does have lots of good breakdowns of it. DMacks (talk) 19:49, 8 October 2022 (UTC)

This increase of course also coincides with a huge rise in anti-trans bigotry in politics in many countries. Yes, correlation does not imply causation, but it's not going to help. Fgf10 (talk) 08:45, 9 October 2022 (UTC)

Berries

Would like help in identifying the species of these berries. I want to pick them, but make sure they are not poisonous. 212.180.235.46 (talk) 11:35, 8 October 2022 (UTC)

It looks like a Pyracantha of some sort: The pulp [of the berries] is safe for human consumption, but it is insipid, and the seeds are mildly poisonous... AndrewWTaylor (talk) 17:28, 8 October 2022 (UTC)

I would like to suggest those berries may be Sea buckthorn. Superficially similar to pyracantha but sea buckthorn have greyer leaves. Information about its edibility is in the link. Richard Avery (talk) 14:34, 11 October 2022 (UTC)

And of course, we're not telling you it's OK to eat them. EEng 20:08, 14 October 2022 (UTC)

Detecting alien spaceships

Some days ago I had a discussion with someone. He said that he once saw an alien spaceship in the sky, and I rejected the notion: I have no idea what was the thing he saw, but if an alien spaceship came all the way to Earth, enter into planetary atmosphere, made a passing-by fly and then fly away, it would have been detected and seen by all the satellites out there. And the usual "the military concealed it all" excuses would not work, we are talking about satellites from many countries, and some of them belonging to the private sector. Even without a proper first contact, it would be the event of the century, all the world would be talking about it and there's just no way to stop something like that.

But then I thought: am I right? do satellites work that way, would they detect a spaceship out there? There are space telescopes, but are they on the look for something unexpected, or stay focused on whatever they are studying right now? Considering that a spaceship would be a tiny object (compared with other celestial bodies) and not following a known orbit, how far away would we be able to detect it? Cambalachero (talk) 15:50, 8 October 2022 (UTC)

Considering that there are approximately 9,000 items larger than a softball orbiting the Earth, all of which are tracked and monitored by the Department of Defense,[1] it seems unlikely that an "alien spaceship" could sneak by. Of course, in the realm of science fiction, sneaky sentient aliens (or time travelers, alternate universe jumpers, etc.) could use any of a variety of methods to troll your friend. 136.56.52.157 (talk) 17:03, 8 October 2022 (UTC)

Or cloaking devices, momentarily disabled when the aliens spot someone who seems like a good target for such trolling. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:16, 8 October 2022 (UTC)

(edit conflict)One should also consider that just because an observer cannot identify something witnessed in the sky, it is not necessarily an "alien spacecraft". I personally had a fairly close encounter with 3 UFOs that flew directly over me in the desert near Yuma, AZ. Although they were "unidentified" (by me) and were "objects" that were "flying", I did not assume they were alien spacecrafts. A year or so later when the F-117 was publicly disclosed, they became identifiable to me. 136.56.52.157 (talk) 17:03, 8 October 2022 (UTC)

They were not sufficiently stealthy? ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:28, 8 October 2022 (UTC)

I have a pair of organic orbital photon sensor arrays that were able to detect them. 136.56.52.157 (talk) 17:50, 8 October 2022 (UTC)

Remember the sticker at the back of each Nighthawk: "If you can read this sign, we wasted US$ 111 million of taxpayer money." ;-) --Stephan Schulz (talk) 00:13, 11 October 2022 (UTC)

Satellites don't scan for UFOs. There are telescopes scanning for asteroids that could hit earth and a big alien spaceship would be picked up by those if it was close enough, but only if it passed through their field of view. Those telescopes only scan the entire sky once every few days. Military radar systems designed to detect strategic nuclear missiles would also detect alien spaceships close to earth, but only cover some parts of the world. Only when it flies in the lower atmosphere it would be picked up by ordinary military radar systems, except when it flies over some remote ocean or Antarctica – and even if detected, only one country's military would know about it. Earth observing radar satellites would detect it if the UFO flies beneath them, but they too only scan the entire earth once a week or so – and would automatically flag it as an aeroplane. Radars tracking orbital debris don't keep the full sky in view permanently; they target the known objects to refine their orbits once every few weeks and occasionally scan for new objects in such a a way that anything orbiting Earth should have passed through their beam. Remember: every sensitive detector has a small field of view. I'm quite sure an alien ship could sneak through if they wanted and carefully planned to avoid such radar beams. PiusImpavidus (talk) 20:24, 8 October 2022 (UTC)

The 900 yard wide asteroid Hermes was discovered 2 to 3 million miles out in 1937 when it was way too dim for the naked eye. Maybe even cats couldn't see it? It was getting 11 miles closer every second and finally reached closest approach 2 days later (still billions of feet above sea level though at least some cats could now see it). Sagittarian Milky Way (talk) 22:54, 8 October 2022 (UTC)

The number of times the planet Venus is mistaken for an unidentified flying object would surprise you. Reports of a strange light in the sky are sometimes traced back to the full moon. 2A00:23D0:6D1:2301:9D6B:19E5:3932:5A51 (talk) 12:49, 9 October 2022 (UTC)

Years ago, my father, who was the secretary of the local astronomy club, got a phone call from the police station in a different city. Apparently the police had been unable to contact the public observatory there after being called by many people who had seen something strange in the sky: two bright dots very close together. Had two planets collided? An alien ship? It turned out to be a conjunction of Jupiter and Venus. PiusImpavidus (talk) 09:13, 10 October 2022 (UTC)

• Detection of intelligent extraterrestrial life is something that try to do, the SETI Institute is one of the more famous organizations that perform and fund this kind of research, but see also Search for extraterrestrial intelligence for more information. If we were to detect an alien civilization capable of interstellar flight, it's going to be one of those studies that does so, not some yahoo in New Mexico probably blitzed on peyote and cheap beer... --Jayron32 18:20, 11 October 2022 (UTC)

self-unscrewing screws

I have a desk at home made partially from glass. They probably stopped making such. My desk is probably 25 years old. There is a glass surface on the top and a metal surface below where you can reasonably place your keyboard and the mouse. The metal surface can telescopically be moved back and forth. It is a computer desk.

Recently while I was working and needed to finish a letter quickly, the metal surface collapsed on to my knees. It turned out this surface rests on a metal rod, and the rod is attached to a metal leg with a screw. I found this screw on the floor. The screw had been sitting there probably for 20 years. Why did it come out? Over the years it unscrewed itself for a tiny angle counterclockwise. And finally my desk dropped. I could describe many similar episodes with other screws and with other mechanisms or constructions. And why do the screws always unscrew themselves, never tighten themselves up? And why does the screw is given this push which is circular although I don't see anywhere rotating parts in my desk? AboutFace 22 (talk) 21:28, 8 October 2022 (UTC)

When the screw was originally screwed in, force was applied, compressing the wood around the screw to make place for the screw. The compressed wood is pushing back. Almost all force is orthogonal to the axis of the screw, but a tiny amount has a net component pushing the screw out. In a world without friction the screw would come out immediately, but the tiny force pushing the screw out cannot overcome the (static) friction. However, occasionally some other force, like when the desk is moved or bumped into, for a brief moment of time exceeds the friction. This causes a microscopic rotation of the screw with a bias towards getting it out. I suppose that 20 years of such microscopic rotations can add up to a very macroscopic one.  --Lambiam 21:57, 8 October 2022 (UTC)

The desk joint is described as all-metal, not metal-into-wood. Presumably the leg is more like a nut (pre-formed threads) than your description as a wood-screw. Bolted joint is our main article. It has a ton of technical engineering and math detail. DMacks (talk) 05:45, 9 October 2022 (UTC)

Why does vibration loosen screws?. Alansplodge (talk) 11:33, 9 October 2022 (UTC)

I have a metal chair. The legs are kept from splaying out (and depositing me on the floor) by two horizontal bars which screw into the legs at either end. Once the screws have loosened a little the legs will splay out a bit. Any tightening vibration will not tighten them because it would have to overcome the weight of the structure acting to move the legs outwards. Any loosening vibration is aided by this and eventually the screws would disengage. However, before this happens a wobbling of the chair warns me to retighten the screws. All this could be avoided by having the screws protrude beyond the channel in the leg which they screw into and placing a nut on the exposed end, but then you would have the problem of hands coming into contact with sharp pieces of metal. 2A00:23D0:6D1:2301:9D6B:19E5:3932:5A51 (talk) 12:46, 9 October 2022 (UTC)

The general problem of loosening bolts and nuts can be obviated by the use of Thread-locking fluid. {The poster formerly known as 87.81.230.195} 90.193.128.129 (talk) 16:01, 9 October 2022 (UTC)

• Screws fall out all the time. The world is an imperfect place... --Jayron32 18:22, 11 October 2022 (UTC)