Wikipedia:Reference desk/Science

The Wikipedia Reference Desk covering the topic of science.

Welcome to the science reference desk.
Want a faster answer?

Main page: Help searching Wikipedia

How can I get my question answered?

  • Provide a short header that gives the general topic of the question.
  • Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
  • Post your question to only one desk.
  • Don't post personal contact information – it will be removed. All answers will be provided here.
  • Specific questions, that are likely to produce reliable sources, will tend to get clearer answers.
  • 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.



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.
 
Choose a topic:
 
See also:
Help desk
Village pump
Help manual


December 1Edit

Why is isospin separated in Gell-Mann–Nishijima?Edit

In the Gell-Mann–Nishijima formula, isospin is separated out:  .

Wouldn't it be simpler to write it as:   (where U is Upness and D is Downness).

In fact, why does isospin exist at all? Shouldn't we just talk about Up/Down same as the other quark flavors?

Ariel. (talk) 18:43, 1 December 2019 (UTC)

You're looking back at some of the history that led to the quark model. At the time, there was just a "particle zoo" with some observed patterns but no unifying model. The Gell-Mann–Nishijima formula is one of the stepping-stones that got us to the quark model and to electroweak unification. The term inside the parentheses gets labeled "hypercharge", and these two terms later lead to weak isospin and weak hypercharge, which have a more fundamental role in the standard model. The original up-down isospin can still be practically useful because there's an approximate symmetry between up and down quarks, which have very similar mass. --Amble (talk) 20:21, 2 December 2019 (UTC)

December 3Edit

atmospheric mercuryEdit

[1] Atmospheric mercury in the fog is poisoning pumas in the Santa Cruz mountains. "The neurotoxin [mercury] is coming out of the ocean through a process that happens in the deep ocean involving mercury."

What is this process dumping mercury into the air from the ocean? Is it a natural and steady process, industrial, natural and worsening from global warming, or what? Does the mercury concentrate in water vapor like fog? Will it get strong enough to affect humans, if it's not affecting us already? This is the first I've heard of this. Thanks. 67.164.113.165 (talk) 06:20, 3 December 2019 (UTC)

The mercury that this is about is not in the air itself (although air can contain elemental mercury); it's organic mercury compounds in the water droplets making up the fog. Here is the original paper from Nature. If the paper talks about the details of formation of contaminated droplets, I missed it on a quick skim. Anyway, Figure 5 may be of particular interest. --76.69.116.4 (talk) 07:24, 3 December 2019 (UTC)

Genetics and probabilityEdit

Given two female cousins - who have only one common grandfather yet no common grandmothers - and who have only uncles yet no aunts, what's the probablity of those cousins to be genetically "unrelated", if neither cousin's mother nor cousin's father's mother are genetically "related" to each other (as far as women of Homo-sapiens can be genetically "unrelated")?

By the way, of course we can disregard the allosomes (gonosomes), because those of the cousins - are genetically "unrelated" - necessarily (per the given data). 87.70.13.99 (talk) 16:13, 3 December 2019 (UTC)

If they truly have one grandfather in common, then basically zero. Are you under the mistaken impression chromosomes are inherited intact or as a whole unit? They are not. See genetic recombination. Nil Einne (talk) 17:27, 3 December 2019 (UTC)
If by "basically" (zero) you mean "almost" (zero), then I agree, but I'm asking about this low probability that is - very close to zero - yet not absolutely zero. 87.70.13.99 (talk) 17:48, 3 December 2019 (UTC)
See the definition of basically zero ? --Askedonty (talk) 18:49, 3 December 2019 (UTC)
Your link doesn't mention the term "basically zero". Anyway, I'm speaking about a probability that is - very close to zero - yet not absolutely zero (just as the rest mass of electron is - very close to zero - yet not absolutely zero, as opposed to the rest mass of photon that is absolutely zero). 87.70.13.99 (talk) 19:04, 3 December 2019 (UTC)
Precisely: "extremely low (but technically not zero)". Read the article. --Askedonty (talk) 19:15, 3 December 2019 (UTC)
The term you have just used, is by no means more precise than the term I had used ("very close to zero"). Anyway, I had been referring to the term "basically zero", rather than to the other term you have just used. 87.70.13.99 (talk) 19:24, 3 December 2019 (UTC)
Actually, the better link from a probability standpoint is almost never, which is a precisely defined term in probability theory. It includes any result which real results, but none-the-less will never happen. For example, there is a real result in the above scenario has real solutions. It is technically possible to build two identical genomes from first principles. You simply need to order the nucleotides of the DNA the same way in both people. That is a real thing; the probability of which is happening is so functionally low as to be almost never happening. What this means is not "this might actually happen" what it means is, although there are real solutions that have this result, it actually never happens from a probabilistic standpoint. Terms like "basically zero" are also used for "almost never" and mean the same thing. In simplest terms, something can re a real result, and still have a probability of almost never happening. The result described by the OP fits that definition. The link provided by Askedonty is a similar concept, but was too oblique a relationship. Almost never is the correct concept from statistics. --Jayron32 20:44, 3 December 2019 (UTC)
I don't disagree with anything you said but note that the OP was asking about 2 genomes being "unrelated" not identical. I guess in the context of their question, this would imply every part of their genome just happened to come from one of their other grandparents by chance. Nil Einne (talk) 21:08, 3 December 2019 (UTC)
Yeah, sorry I wasn't clear. It almost never will happen that two such cousins will have completely dissimilar genetic codes. They will almost surely have genetic codes which are very close to the predicted relatedness; and will almost never have DNA which shows any significant variation from that, almost surely not zero relatedness. In terms of statistics, the terms "almost never" and "almost surely" means that, while the result of "zero relatedness" is a real result, there is no chance of it happening, indeed there is very slim chance of any result outside of some small window around the predicted statistics. That is because the law of large numbers is at play here. There are a stupidly large number of genes and a stupidly large number of chromosomal crossover events that actual offspring basically almost surely match the predicted results. --Jayron32 21:24, 3 December 2019 (UTC)
I guess the hypothesis of the OP could be elaborated on the Law of independent assortment but I'm leaving it there as to putting numbers behind the number of characters to be slalomed between within the course of four generations, to try getting at the hypothesis. --Askedonty (talk) 21:59, 3 December 2019 (UTC)
See user:eric's comment below, followed by my response. 87.70.13.99 (talk) 23:34, 3 December 2019 (UTC)
On my part the avantage of my link is that it deals with text strings and that's reputedly very similar to DNA. --Askedonty (talk) 21:11, 3 December 2019 (UTC)
(ec) Doesn't that article say that the probability has to equal 0 to be "almost never"? An infinite number of coin flips will "almost never" be all tails? A finite number of coin flips being all tails has a probability greater than 0, and is not "almost never".—eric 21:17, 3 December 2019 (UTC)
Correct, and that's why I (the OP) asked my question, which is more analogous to a question about a finite (rather than an infinite) number of coin flips being all tails. 87.70.13.99 (talk) 23:34, 3 December 2019 (UTC)
Is this even getting into the territory of "virtually zero" or "basically zero"? Based on a less than high school understanding of genetics and the premises there is a fairly high probability that any one pair will be unrelated. And can you just raise that to the power of 22? Anyone who knows more got a napkin handy?—eric 15:53, 4 December 2019 (UTC)
The point is, there isn't much use in entertaining the possibility of events where the math makes it clear that there is not an expected result to occur like that until long after the heat death of the universe. Anyone with a modicum of understanding of the fantastically large numbers involved doesn't spend the intellectual energy necessary to consider such "probabilities" as worth the time and energy to compute, let alone consider a real chance. You can get a number, if you wanted to. I'll concede that the number you get is more "not meaningfully enough larger than zero without invoking false precision to be useful to draw conclusions with" rather than "honest-to-god-actually zero", though the former can be safely called "zero" without any meaningful difference to understanding the concepts at hand. Just because you can do math and get a number doesn't make it a useful number. --Jayron32 16:30, 4 December 2019 (UTC)
Sorry for hijacking the thread, but let me try and ask another way. If crossover happens all the time, or almost all the time, chances are in the "heat death of the universe" range. If crossover happens only most of the time, chances start to get better. Almost all search results are for genetic algorithms, not genetics, and can give some pretty low values. Is it as this page from Stanford implies: "You didn't get any whole chromosomes from either parent", or maybe say a 20% chance you end up getting a whole chromosome? Crossover value and Chiasma (genetics) don't help much.—eric 19:43, 4 December 2019 (UTC)
Ah, nevermind: "This “obligatory CO rule” reflects the fact that at least one crossover is required to ensure correct chromosome segregation at meiosis"[2]eric 20:10, 4 December 2019 (UTC)

December 4Edit

What building collapses resembled the WTC towers collapses?Edit

What kind of dynamic loads were the most responsible for bring them down? Thank you. 104.162.197.70 (talk) 01:37, 4 December 2019 (UTC)

The parts of the buildings above where the planes hit. ←Baseball Bugs What's up, Doc? carrots→ 02:25, 4 December 2019 (UTC)
The collapses were examples of progressive collapse; see that article for other instances. (Collapse of the World Trade Center could maybe use a little editorial work.) --47.146.63.87 (talk) 04:58, 4 December 2019 (UTC)
  • Not many. The WTC (also the Aon Center in Chicago and an IBM building in Seattle) are examples of Fazlur Rahman Khan's framed tube construction. These are efficient structures at providing large clear floor areas, because they concentrate much of their structural strength into the outside wall. This is a strong structure, but it also means that any large impact is also likely to damage more of it than a more traditional structure where the framing is distributed across the plan. Thus any collapse would be of a different nature. See Construction of the World Trade Center and Collapse of the World Trade Center. Fortunately no other such buildings have suffered an attack like that.
Even the Sears Tower, which uses a bundled framed tube structure, would have less such dependency on its outside layer. Andy Dingley (talk) 18:51, 4 December 2019 (UTC)
I'm not much of an expert on skyscraper architecture, but are you saying that the World Trade Center, unlike many other skyscrapers, used Load-bearing walls in a way that made them uniquely susceptible to the kind of collapse that occurred after the towers were struck by the planes? --Jayron32 19:03, 4 December 2019 (UTC)
No, I said that the WTC (also the Aon Center in Chicago and an IBM building in Seattle) are examples of Fazlur Rahman Khan's framed tube construction. Andy Dingley (talk) 19:11, 4 December 2019 (UTC)
Yeah, I read that, but I was asking instead about your statement "they concentrate much of their structural strength into the outside wall". Is that what is meant by a load-bearing wall or is that something else entirely? I apologize that the source of my confusion wasn't clear. --Jayron32 19:15, 4 December 2019 (UTC)
It's a framed tube. It's regarded as innovative. Now in some ontological sense, it's a wall and it's load-bearing. But you won't learn much from that article, you'd be better at the linked one. Load-bearing walls have been around nearly as long as walls, and this is unlike most others. Andy Dingley (talk) 19:19, 4 December 2019 (UTC)
Got it. Thanks for clarifying. --Jayron32 19:20, 4 December 2019 (UTC)

Twins versus conjoined twinsEdit

Why do we often see twins of the opposite sex (i.e., a brother and a sister) ... but we never see conjoined twins of the opposite sex? Every time I see conjoined twins, they are of the same sex. Also, is there such a thing as conjoined triplets (or a higher number, besides twins)? My guess is "no" ... but, why not? Thanks. Joseph A. Spadaro (talk) 18:01, 4 December 2019 (UTC)

By the same reason that you will never see identical twins of the opposite sex. You can also see Twin#Degree_of_separation. As to identical triplets or conjoined triplets, they are also possible. Ruslik_Zero 18:40, 4 December 2019 (UTC)
Just to add a little more to Ruslik0's excellent response; the term twins actually refers only to two individuals who are gestated at the same time; but there are actually many different types of twins based on how there came to be two individuals in that womb together. Twin#Types and zygosity discusses all of these in some detail, but perhaps goes a bit too deep in the weeds. We usually think of twins coming in two main types, identical twins and fraternal twins, with identical twins being formed by a single zygote and fraternal twins being formed by two different zygotes. Fraternal twins are, except for being gestated at the same time, otherwise just like non-twin siblings. The share a 50% relationship in genetics, for example. Also, the chance of two fraternal twins being of the same or different biological genders are exactly the same for any other sibling pairs: 50% of them will be one of each, 25% of the time they will both be boys, and 25% of the time they will both be girls. Fraternal twins cannot be conjoined because at no point in their development were they ever the same individual. Identical twins, on the other hand begin as a single individual zygote that splits early in development into to identical, but separate, individual zygotes. Conjoined twins happen basically because this "splitting" process is incomplete. Because identical twins are genetically identical, they are always the same biological sex at birth. (as an aside, this does not preclude one of a set of identical twins from having a different gender at a later point in their life.) Because conjoined twins are always identical twins, and because identical twins are always the same biological sex as each other, conjoined twins are always of the same biological sex. --Jayron32 18:54, 4 December 2019 (UTC)
Nitpick: the more standard terminology today (as used by bodies such as the WHO) is to use "sex" to refer to a person's sex chromosome genotype. See sex and gender distinction. --47.146.63.87 (talk) 20:02, 4 December 2019 (UTC)
Good point. Thank you for bringing that up. So corrected.--Jayron32 23:08, 4 December 2019 (UTC)
Just because nature can do funky things, separate zygotes can fuse, meaning a fertilization event that would normally lead to fraternal twins can instead lead to a single chimeric offspring. And there are rare cases of sesquizygotic twins, where what starts as a single ovum is fertilized by two separate sperm, with the resulting [blastomere]] later separating into twins. Apparently there's an increased likelihood that the cells with the two different paternal generic lineages form separate clusters rather than being homogeneously mixed. If one of the two involved sperm were genetically X and the other Y and the two parts of the blastomere had different relative amounts of these lineages, they can lead to twins with different sexes. Doi:10.1056/NEJMoa1701313 and refs therein is an interesting read! "All it takes" is for the twinning event to be incomplete in this case, and you have conjoined twins of opposite sex. DMacks (talk) 05:03, 5 December 2019 (UTC)
Indeed, edge cases and oddities do exist, and thank you for bringing that up. "All it takes" is some actual examples; though. We can hypothesize all day, but of the billions of births in history, do we have examples of mixed-sex conjoined twins? --Jayron32 12:20, 5 December 2019 (UTC)
No examples yet known for humans (and apparently armadillos are the only other placental species to have monozygotic twinning). There is one report of conjoined phenotypically different twins,(doi:10.1002/ccr3.2113) but not developmentally oppositely sexed. DMacks (talk) 15:08, 5 December 2019 (UTC)

Thanks! Makes sense. But, back to my question about conjoined triplets, etc. The example that an editor gave above was about three children (triplets), but only two of the three were conjoined. My original question was asking about all three triplets (or more) being conjoined. Does this happen? Why not? Thanks. Joseph A. Spadaro (talk) 04:29, 5 December 2019 (UTC)

[3]. Found on a first-page google search. --Jayron32 12:20, 5 December 2019 (UTC)
The part unsaid is that there is a difference between what is possible and what is likely to survive to birth. Multiple births greater than twins are relatively rare in the first place, so you'd be multiplying one unlikely occurence against another unlikely occurence just to have conjoined triplet or quads develop at all. Combine that un-likelihood with the risks associated with multiple births and it's no wonder you don't hear about them being born. Matt Deres (talk) 14:30, 6 December 2019 (UTC)
@Matt Deres: Yes, excellent points! Exactly what I was thinking. Joseph A. Spadaro (talk) 04:50, 7 December 2019 (UTC)

Best tree for carbon captureEdit

Which is the best species of tree for carbon capture? Evergreen or deciduous? Broad-leaved or narrow-leaved? Larger or smaller? Or is it just the species that grows fastest, i.e. the first to reach maturity? Am not sure if any species have been named in the various election manifestos from the political parties currently published in the UK. Perhaps they would all just go for the cheapest one? 86.190.108.100 (talk) 18:59, 4 December 2019 (UTC)

There is a variety of sources here where you can research some of the answers for your question; I will note as an aside that I would think that the best kind of tree to plant would be the ones that are native to, and thus would grow best in, the particular area where you live, and thus there isn't a "one tree fits all" answer for every ecosystem in the world; the world already has a problem with monocultures and loss of biological diversity, and I would think that the proper response in terms of which plants to encourage to grow would be different (for some places, trees may not even be the correct response). But on the narrow nature of the original question, there's several sources in my link for them to choose from. --Jayron32 19:09, 4 December 2019 (UTC)
Is the best carbon capturer even neccessarily a tree? Perhaps there are grass or even algae species that outperform trees. Roger (Dodger67) (talk) 19:14, 4 December 2019 (UTC)
This source gives some analysis of the promises - [4]: Tories 30 million a year, LibDems 60 million, Labour 60 million until 2025, then 140 million 2025-2030, and 100 million 2030-2040, Greens 70 million. But there's not much detail on types there. Labour says in its Plan for Native "We will plant mixed native woodlands". But I don't think the others don't give much detail. 86.190.108.100 (talk) 20:11, 4 December 2019 (UTC)
  • One thing that many politicians get wrong is that when a tree (or some algae or grass) captures some carbon, when it dies and either rots or is burned it releases all of that carbon right back into the atmosphere. What you really want to do is to grow something and them bury it, make furniture or houses out of it, create a new forest and keep the forest in place so that when trees die new trees replace them, or figure out some other way to keep the carbon from going back into the environment. --Guy Macon (talk) 20:35, 4 December 2019 (UTC)
    While a tree may die and return its carbon to the atmosphere, a healthy, mature, permanent forest would become an essentially permanent store of carbon. Planting a tree in your front yard is not a permanent solution; allowing and encouraging fallow land to be reclaimed by the local ecosystem (which may be a forest) would. Increasing population density (building up rather than out) would. Etc. --Jayron32 12:10, 5 December 2019 (UTC)
Maybe the homes of the future will be made of grass and algae? But that doesn't sound like such a vote-winner. Martinevans123 (talk) 20:47, 4 December 2019 (UTC)
Straw-bale construction is already a thing, with somewhat more success these days than the first little pig had. HiLo48 (talk) 04:08, 5 December 2019 (UTC)
For "carbon capture", the role of phytoplankton in the carbon cycle can't be beat -- but political parties can't get votes and greenies can't get taxpayer funding from them. 107.15.157.44 (talk) 04:56, 5 December 2019 (UTC)
AIUI plankton that manages to avoid being eaten eventually becomes sludge on the sea floor. (Some of) this sludge in turn becomes petroleum after spending some millenia in a geological pressure cooker. Roger (Dodger67) (talk) 08:34, 5 December 2019 (UTC)

Tangent Alert:
Whereas trees often vote for their favorites. ←Baseball Bugs What's up, Doc? carrots→ 06:12, 5 December 2019 (UTC)
...Thus explaining the Green party. --Guy Macon (talk) 06:15, 5 December 2019 (UTC)
Some trees seem decidedly opposed to elections at all.[5] DMacks (talk) 06:27, 5 December 2019 (UTC)
The headline "Tree falls on polling site, still able to vote" suggests that although the tree fell, it was still able to cast a vote. A feel-good story! ←Baseball Bugs What's up, Doc? carrots→ 06:42, 5 December 2019 (UTC)
Some trees try to get elected to Congress: [6]  107.15.157.44 (talk) 06:46, 5 December 2019 (UTC)
Some have been: Fernando Wood William B. Pine. And going the other way, The Senator (tree). DMacks (talk) 07:05, 5 December 2019 (UTC)

Back to the point: “With increased species richness, more carbon is stored both above and below ground – in trunks, roots, deadwood, mould and soil. You can roughly say that a diverse forest stores twice the amount of carbon as the average monoculture.” From Forests containing several tree species could store twice as much carbon as the average monoculture plantation, research finds. Alansplodge (talk) 17:44, 5 December 2019 (UTC)
And from a UK perspective: Trees as carbon stores lists species with high, medium and low carbon sequestration rates. Only three in the "high" category are native to Britain, so I suspect that the Labour Party's emphasis on native species is more to do with improving wildlife habitat than with carbon capture. One of the trees listed as "high" is the dreadful Leyland cypress, a forest of these things would be a wildlife desert. Alansplodge (talk) 17:50, 5 December 2019 (UTC)

December 5Edit

Question of history: 1939 Standard E1 typeEdit

During WWII, from 1939 to 1945, Wilhelm Gutbrod produced in his Standard Fahrzeugfabrik, the freight three-wheeler type E1. According to forum entries, the design changed from a RR-layout to a FF chain-driven front wheel, like Oscar Vidal & Sons Tempo company did on their vehicles. As the forum user also "renewed" the nameplate, I really get doubt about the design change. [7] As I don't get access to the book, https://books.google.de/books?id=7VGfvgEACAAJ or similar, I would like to ask, is there a reliable book source, confirming this change. --Hans Haase (有问题吗) 11:26, 5 December 2019 (UTC)

A relevant courtesy link for those interested. {The poster formerly known as 87.81.230.195} 2.217.209.178 (talk) 19:05, 5 December 2019 (UTC)
@Hans Haase: Since you already have a precise idea of the source you want, you might want to ask that question at WP:RX. TigraanClick here to contact me 10:42, 6 December 2019 (UTC)
Thx, at the moment I am not sure if the book really has information about and further research leaded me o the word "Einheits-Dreirad-Lieferwagen" as meaning of a design-standardisized three-wheeler delivery-vehilce. These innovation minimizing plans remembers to an unique design-standardisized truck, like Borgward produced, also Opel, a later GM subsidiary. Whats there about? --Hans Haase (有问题吗) 11:49, 6 December 2019 (UTC)

December 6Edit

New organic chemistry 3D resourcesEdit

What other wikiprojects than WT:CHEM should I tell about https://qrchem.net and https://rschemistry.com which were just announced. EllenCT (talk) 06:15, 6 December 2019 (UTC)

There is also the Wikipedia talk:WikiProject Chemicals which is more specific for the stuff at https://qrchem.net, but the PubChem site itself has more info. Our articles usually have the link to the same 3D manipulable image already. Graeme Bartlett (talk) 11:05, 6 December 2019 (UTC)

Nonhuman aesthetic responses to natural phenomenaEdit

Is there any evidence that nonhuman species show an aesthetic interest in natural phenomena (e.g. rainbows) as humans do? 188.74.64.13 (talk) 21:14, 6 December 2019 (UTC)

No.[8]Baseball Bugs What's up, Doc? carrots→ 21:23, 6 December 2019 (UTC)


After a quick search through the online archives of the journal Ethology, I found:
  • Gordon M. Burghardt, Alumni Distinguished Professor in Psychology and in Ecology and Evolutionary Biology at the University of Tennessee
This author has written peer-reviewed works and full-length books, such as The Genesis of Animal Play and The Cognitive Animal: Empirical and Theoretical Perspectives on Animal Cognition.
You probably aren't going to find satisfaction from a very succinct "yes"/"no" answer; but at least you can see how one expert in a relevant field has framed some of the issues.
Nimur (talk) 21:30, 6 December 2019 (UTC)
Somewhat related:

Darwin hypothesized that a female “aesthetic faculty”—literally an evolved “taste for the beautiful” that is exercised during mate choice—constitutes a distinct evolutionary force that leads to the evolution of ornamental traits in animals.

Prum, Richard O. (2013). "Coevolutionary aesthetics in human and biotic artworlds". Biology & Philosophy. 28 (5): 811–832. doi:10.1007/s10539-013-9389-8. ISSN 0169-3867.
2606:A000:1126:28D:E579:84AC:9408:ADE (talk) 22:07, 6 December 2019 (UTC)
 
Oh! What a sexy web she weaves!
What "aesthetics" would factor into a tarantula's choice for a mate? ←Baseball Bugs What's up, Doc? carrots→ 22:53, 6 December 2019 (UTC)
Don't know about tarantulae, but Cyrtophora citricola males evidently consider the aesthetics of a female's web when selecting a mate (who then eats him during or after mating): [9]. 2606:A000:1126:28D:E579:84AC:9408:ADE (talk) 00:39, 7 December 2019 (UTC)


December 7Edit

No hair conjecture for black holes, locationEdit

Doesn’t the statement that black holes can be distinguished only by mass, charge, and angular momentum neglect the fact that they are also distinguished by different locations and linear momentums?Rich (talk) 08:54, 7 December 2019 (UTC)

How does hair figure into it? ←Baseball Bugs What's up, Doc? carrots→ 13:14, 7 December 2019 (UTC)
Our article on the no-hair theorem describes what it means, and the metaphorical origins of its name. For the OP, the speed and location of an object doesn't affect its behaviour, so isn't considered by the theorem. LongHairedFop (talk) 15:00, 7 December 2019 (UTC)
To answer the OPs question: As LHF above cites the correct article, you can read in that article how the choice of reference frame can eliminate things like position and linear momentum by setting them to zero. The three measurements that remain in any reference frame, even one comoving with the black hole itself, are the angular momentum scalar, the electric charge, and the mass. All other measurements are either frame-dependent or are lost when the in-falling matter crosses the event horizon.--Jayron32 06:19, 8 December 2019 (UTC)

Power of SiberiaEdit

The Power of Siberia article says:

1. Deliveries to China started on 2 December 2019.

2. The pipeline's working pressure is ensured by nine compressor stations[18][12] with a total capacity of 1,200 MW. Construction of compressor stations will be completed by 2022.

So the pipeline is currently delivering gas, but some compressor stations have not finished construction yet. My guess is that the pipeline is currently operating at lower pressures, and thus not using its full possible capacity yet. And when all compressor stations are completed, it will operate at higher pressure and thus have greater capacity. Is my guess correct? Mũeller (talk) 11:03, 7 December 2019 (UTC)

Couldn't find exact confirmation but A huge Siberian pipeline binds Russia and China, as gas flows for the first time (Washington Post, 12/02/2019) says: "In the coming year, the gas flow in the Power of Siberia pipeline to China will be limited, amounting to 4.6 billion cubic meters in 2020, according to Gazprom, and rising to 10 billion cubic meters in 2021. But Gazprom has declared its ambition to provide 38 billion cubic meters to China by 2025 and to supply a quarter of China’s liquefied natural gas imports by 2035". Alansplodge (talk) 14:47, 7 December 2019 (UTC)
Thank you for the input. I'll keep digging.Mũeller (talk) 11:41, 8 December 2019 (UTC)

conservation status of plantsEdit

Why do some entries for plants include conservation status and others do not?

It is solely due to discretion of editors. Ruslik_Zero 20:49, 7 December 2019 (UTC)
Because we are not yet perfect? Feel free to add it where you can. HiLo48 (talk) 20:51, 7 December 2019 (UTC)

December 8Edit