Wikipedia:Reference desk/Archives/Science/2022 December 13

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December 13

Starting the engine of military vehicles

Random thing that someone was wondering about in the bar tonight. Do tanks, fighter planes and attack helicopters have a set of keys for the doors and the ignition? — Preceding unsigned comment added by 146.200.126.234 (talk) 00:04, 13 December 2022 (UTC)

I don't have a general authoritive answer, but keys have long been used in private ownership vehicles because of theft. Industrial vehicles such as bulldozers have traditionally needed no key for starting, as practically nobody wanted to steal them.

My father bought a World War 2 surplus British made tank. There was no key - anybody could enter and start it. It had an aircraft-style ignition lever switch - off/one/two/both (the engine had 2 spark plugs per cylinder- you are supposed to test running on one set of plugs at a time, to prove both work) and a push-button to crank it.

Last year, a former iron curtain country had some sort of celebration in which their state museum supplied a restored Russian made tank (T54 or similar). Leaving it on public display, they took the battery out, thinking this would immobilise it. A couple of old guys, probably a somewhat drunk, showed up and they had served years before in the same sort of tank. They knew it had an emergency air start system in case of a dead battery. So they started the tank using the air system and drove off with it.

Our army sold of a few old Armoured Personnel Carriers (APC). I inspected one (M113 or similar) at the dealer's yard. They invited me to start it - it needed no key. It had a simple lever on/off switch for electrical power, and a push-button to activate the starter motor.

There are a number of military aircraft start procedure videos on YouTube. There's no key.

One can imagine a scenario: "We are under overwhelming fire. Quick, corporal, start the truck and let's get out of here!" "Uh, sorry Sarge, I dropped the keys in the mud. Can't find them now." Dionne Court (talk) 00:54, 13 December 2022 (UTC)

This article in ARMY Magazine, criticising the US Commercial Utility Cargo Vehicle or M880 (a military pick-up truck), cites the provision of a common ignition key as a disadvantage; "Imagine trying to bug out and having to fumble for a key to start the truck". Alansplodge (talk) 22:21, 13 December 2022 (UTC)

Hello user with IP 146.200.126.234, nope, most military vehicles and airplanes in general (not just military) don't use keys, i've heard that humvees don't use keys, nor do tanks, as shawn nelson proved, most aircraft don't use keys, aside from smaller GA aircraft like the Cessna 172 and bushplanes that have a keyed magneto switch, as those aircraft are more likely to be kept in an unsecure airport, military and civil aircraft are always always kept in very secure airports, often having more then a few hundred CCTV and thermal CCTV cameras, these aircraft also relies on a rather complex procedure to start and prep for take off, people have stolen unkeyed aircraft before, but it's often a little twin prop, not sure if anyone has ever stolen a 737 for instance.

Military aircraft are the same, no keys, but good luck getting into a military base, and then there's starting it.

Vintage fighters like the spitfire had their own security feature, huge prop torque that even experienced pilots have trouble handling. OGWFP (talk) 21:59, 16 December 2022 (UTC)

Exactly what I was going to say -- there's no need for military vehicles to have keys to get in and/or to start, because these vehicles are (supposed to be) guarded whenever not in use! 2601:646:8A81:6070:CC33:2635:A453:3355 (talk) 06:31, 19 December 2022 (UTC)

Examples Where Genetics was used to determine definitions of genus and species

I recall that there were examples where the definition of a species, genus, etc. were redefined based on genetic analysis. E.g., we thought that Chimp was a species but we changed it to be a genus or we thought a Sea Horse was a fish but we changed it to an Anthropod (I'm making that last one up but I think the first one might be true). I can't remember where I read this though and I've looked through Wikipedia and my books and can't find anything. Would appreciate any examples and refs. MadScientistX11 (talk) 00:59, 13 December 2022 (UTC)

Here are some examples; there are probably countless more.

• The Arctic warbler was formerly thought to include various populations that breed in Asia, but these are all now considered distinct species.
• The black Sumatran langur was formerly considered a subspecies of the brown long-eared bat, but is now treated as a separate species.
• The black-and-white langur was formerly considered a subspecies of the black-crested Sumatran langur, but is now treated as a separate species.
• The Calabria pine vole was formerly considered a subspecies of Savi's pine vole, but is now treated as a separate species.
• The East Sumatran banded langur was formerly considered a subspecies of the Raffles' banded langur, but is now treated as a separate species.
• The European green toad was formerly thought to include various mainly Asian populations, but these are now considered distinct species; together they have been assigned a new genus, Bufotes.
• Imaizumi's red-backed vole was formerly considered a subspecies of the Japanese red-backed vole, but is now provisionally treated as a separate species.
• The Japanese long-eared bat was formerly considered a subspecies of the Sumatran surili, but is now treated as a separate species.
• The Siberut langur was formerly considered a subspecies of the Mentawai langur, but is now treated as a separate species.

 --Lambiam 07:56, 13 December 2022 (UTC)

@Lambiam Thank you those are fantastic!!! Sorry for the late reply. I got busy and only just remembered that I asked this question now. MadScientistX11 (talk) 18:59, 19 December 2022 (UTC)

For an example regarding some species of gulls, see Larus#Ring species. Long story short – we thought they were a Ring species, but a recent genetic study (linked as a reference) has shown that it's even more complicated than that. {The poster formerly known as 87.81.230.195} 90.213.188.15 (talk) 14:21, 13 December 2022 (UTC)

Thanks. That is very helpful as well. I was actually going to use that Gull example as part of my argument. It's good to know that it is more complicated... I mean I wish it wasn't but I'm glad I know now rather than after I submit the paper. Thanks! MadScientistX11 (talk) 19:02, 19 December 2022 (UTC)

Metallising fluorine

Resolved

Has anyone ever measured the pressure necessary to form an expected high-pressure metallic phase of F₂? Or calculated what it theoretically ought to be? Double sharp (talk) 03:07, 13 December 2022 (UTC)

According to this 2020 paper, it apparently has never been experimentally found (well, no surprise given that it seems like a safety nightmare), but that doesn't exclude it having been calculated. Double sharp (talk) 04:14, 13 December 2022 (UTC)

Per this 2020 paper there have been experiments (with inconclusive results) and the theoretical metallisation pressure for fluorine is 2500 GPa (with a novel tetragonal P4₂/mmc structure). So I've once again answered my own question. Double sharp (talk) 04:18, 13 December 2022 (UTC)

Updated metallization pressure (and also the French article). Don't think anyone has calculated it for radon. Double sharp (talk) 04:35, 13 December 2022 (UTC)

Scientific articles about beef versus Impossible Burger that are not commissioned by the latter?

I've been seeing a lot of the 89% statistic about "global warming potential" from the life cycle analysis that Impossible Foods commissioned from Quantis. This number seems to be repeated commonly, and so I was looking for other studies/scientific articles about the same topic that were not commissioned by Impossible Foods so I could further evaluate the claim. 777burger ^{user talk contribs} 03:49, 13 December 2022 (UTC)

Producing an adequate life-cycle assessment of a product in conformance with the ISO 14040 and 14044 framework and guidelines is a substantive effort of a type that does not help one to earn scientific brownie points. Such a study is unlikely to be undertaken by a scientific establishment unless specifically commissioned. Prior to publication, the LCA was reviewed by an independent panel of academic experts, who found no major issues. In particular, it found that that the methods used are scientifically and technically valid. The report produced by Quantis can be downloaded from the Web,^[1] and is detailed enough that anyone who is interested can check that data from other studies have been properly cited and reproduced and can check the computations. It would be interesting to make a comparison with other "fake meat" products, but I bet that for most one would find very similar results. The report can be read more as an indictment of run-away meat production than as an ad for specifically Impossible Foods. One might even say that beef is the more impossible food.  --Lambiam 07:26, 13 December 2022 (UTC)

What is thirtylone?

Transferred from Computing desk

i wanna do some research about What is thirtylone?if you have the idea about you can help me in my research Elsiewright343 (talk) 13:44, 13 December 2022 (UTC) — Preceding unsigned comment added by 95.145.0.90 (talk)

As far as I can tell, it's whatever anyone wants it to be. There doesn't seem to be any single real chemical compound with that name, and nothing recognized as such with a CAS number. It seems to usually be used for various forms of amphetamines or analogs of MDMA, but basically as a name it gets used by the illicit designer drug community for whatever new compound they come up with in these families as existing compounds get banned. Don't buy it, don't do research on using it, as you have literally no idea what you are getting. You don't know what compound they are even promising, let alone whether it is actually containing that compound, in what purity, what else it is mixed with, and I guarantee zero research or testing on safety. --OuroborosCobra (talk) 15:52, 13 December 2022 (UTC)

@Elsiewright343 It is here on Chemspider and here on wikipedia. I wouldn't touch it with the proverbial barge-pole. Mike Turnbull (talk) 16:18, 13 December 2022 (UTC)

I found this and am providing this as is, no comment. --Ouro (blah blah) 04:57, 17 December 2022 (UTC)

Help

What was the most recent common ancestor of dinosaurs and mammals? Allaoii ^talk 19:31, 13 December 2022 (UTC)

It would have been whatever animal existed when Sauropsids (reptiles, dinosaurs, and birds) and Synapsids (mammals and their reptile-like ancestors) diverged, probably living sometime in the Pennsylvanian, likely earlier than 306 million years ago, when the oldest known synapsid evolved. --Jayron32 19:39, 13 December 2022 (UTC)

You are looking for a basal amniote. -- Verbarson  ^talk_edits 19:43, 13 December 2022 (UTC)

i remember reading something that named a specific creature, im trying to find its name Allaoii ^talk 20:01, 13 December 2022 (UTC)

I'm not sure we know it down to that level of precision. The vast majority of species have been unidentified. It seems unlikely in the extreme that the specific species that was the MRCA is known. --Jayron32 21:11, 13 December 2022 (UTC)

well it was star trek... Allaoii ^talk 21:27, 13 December 2022 (UTC)

Ah, the Voyager episode "Distant Origin." It claimed that MRCA to be eryops, which is probably not correct, since it is an amphibian that lived after the first reptiles evolved, and so isn't an ancestor of either dinosaurs or us. Also, the organism they pictured in the episode is not an eryops at all. According to Memory Alpha, the pictured animal is likely a gorgonops, which is already a mammal like reptile. It might be among our ancestors, as a stem group leading to all mammals, but that would already put it after the split between sauropsids and synapsids. So, yeah, Star Trek got this wrong in a lot of ways. --OuroborosCobra (talk) 21:35, 13 December 2022 (UTC)

...wanna be nerd friends? Allaoii ^talk 21:37, 13 December 2022 (UTC)

that reminds me, is the "most evolved dinosaur" they showed real, and if so, what is it? Allaoii ^talk 20:38, 14 December 2022 (UTC)

"Most evolved" is meaningless. All organisms alive on Earth at the same time are equally evolved. --User:Khajidha (talk) (contributions) 16:52, 16 December 2022 (UTC)

in the episode im talking about they showed a dinosaur that was "most evolved" toward humanoidness Allaoii ^talk 20:15, 16 December 2022 (UTC)

well most evolved before they died off Allaoii ^talk 20:16, 16 December 2022 (UTC)

The idea that dinosaurs would evolve toward "humanoidness" reminds me of an ecology concept that is being reevaluated called monoclimax, which I apparently need to write a page for now. Anyways, the idea seems to ignore the value of biological diversity. Etippins (talk) 16:30, 18 December 2022 (UTC)

I think here on the Reference desk we're required to say seagulls. – b_jonas 15:30, 19 December 2022 (UTC)

??? Allaoii ^talk 19:43, 19 December 2022 (UTC)

you realize this is star trek we're talking about here, and that question is a question about an in-world element that was presented a science, im asking how acurate it is. Allaoii ^talk 19:46, 19 December 2022 (UTC)

Try this. Alansplodge (talk) 22:39, 13 December 2022 (UTC)

read the other replies before commenting Allaoii ^talk 22:51, 13 December 2022 (UTC)

Yes. I was providing a reference, this being a reference desk. Alansplodge (talk) 15:07, 14 December 2022 (UTC)

one of the other replies already answered my question. Allaoii ^talk 17:17, 14 December 2022 (UTC)

This is the reference desk, not the answer desk. Alansplodge did exactly what they were supposed to. --Jayron32 19:52, 14 December 2022 (UTC)