I have been adding data about {{Q|122371999}} (a modern-day fossil-hunter, after whom ''[[Turnersuchus hingleyae]]'' is named) to Wikidata; and found a source that says she also has a gastropod named after her. Can anyone suggest what taxon that might be, please? <span class="vcard"><span class="fn">[[User:Pigsonthewing|Andy Mabbett]]</span> (<span class="nickname">Pigsonthewing</span>); [[User talk:Pigsonthewing|Talk to Andy]]; [[Special:Contributions/Pigsonthewing|Andy's edits]]</span> 15:45, 11 September 2023 (UTC)
I have been adding data about {{Q|122371999}} (a modern-day fossil-hunter, after whom ''[[Turnersuchus hingleyae]]'' is named) to Wikidata; and found a source that says she also has a gastropod named after her. Can anyone suggest what taxon that might be, please? <span class="vcard"><span class="fn">[[User:Pigsonthewing|Andy Mabbett]]</span> (<span class="nickname">Pigsonthewing</span>); [[User talk:Pigsonthewing|Talk to Andy]]; [[Special:Contributions/Pigsonthewing|Andy's edits]]</span> 15:45, 11 September 2023 (UTC)
:My guess is this is sloppy journalism; there was ''another'' person named [https://www.jstor.org/stable/3327 Marjorie R. Hingley] who my google searches are showing was something of an expert in gastropods. I suspect (though cannot find any evidence of either) that the gastropod in question was named for Marjorie and not Lizzie. I can't find ''anything'' else, and the only google results I get that have both the name "hingley" and the word "gastropod" are 1) the specific little factoid on a few articles about Lizzie, and several articles written by Marjorie R. Hingley. --[[User:Jayron32|<span style="color:#009">Jayron</span>]][[User talk:Jayron32|<b style="color:#090">''32''</b>]] 17:55, 11 September 2023 (UTC)
:My guess is this is sloppy journalism; there was ''another'' person named [https://www.jstor.org/stable/3327 Marjorie R. Hingley] who my google searches are showing was something of an expert in gastropods. I suspect (though cannot find any evidence of either) that the gastropod in question was named for Marjorie and not Lizzie. I can't find ''anything'' else, and the only google results I get that have both the name "hingley" and the word "gastropod" are 1) the specific little factoid on a few articles about Lizzie, and 2) several articles written by Marjorie R. Hingley. --[[User:Jayron32|<span style="color:#009">Jayron</span>]][[User talk:Jayron32|<b style="color:#090">''32''</b>]] 17:55, 11 September 2023 (UTC)
Revision as of 17:55, 11 September 2023
Welcome to the science section of the Wikipedia reference desk.
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.
Hi. McMaster-Carr list this ceramic material[1] as having a hardness of "Rockwell 45N 83". I interpreted that to mean that it's on the Rockwell scale, specifically the Superficial 45N scale, and that the score is 83.
However, various online hardness conversion charts[2][3][4] has the Rockwell Superficial 45N scale maxing out at around 75 to 77, and 83 is way over that.
I would not call 83 "way over" 77. With these scales there is no theoretical limit on the hardness, so it is a reasonable assumption this reflects a measurement of a hardness somewhat above the usual range for this specific test. --Lambiam09:04, 6 September 2023 (UTC)[reply]
September 5
Cosmos
Regarding dark matter, Wikipedia, by Ethan Siegel, what we don't know #3., may have been around if there's more than one big bang and if not then the individual particles are made from new matter and continue being produced until all energy has been deleted throughout the cosmos. Jobie Steppe 2600:1702:2EB0:1E80:91AB:7FDA:9AFC:8588 (talk) 00:12, 5 September 2023 (UTC)[reply]
Is xenon-135's 3 megabarns of neutron capture still the strong force?
Even if every neutron that comes within 9,772 femtometers of the center had a 100% chance of absorption that's still a lot further than any strong or weak nuclear force is generally said to reach. Doesn't the nuclear binding force decay very rapidly beyond a handful of proton radii? Sagittarian Milky Way (talk) 02:18, 5 September 2023 (UTC)[reply]
It's worth noting that while the cross section has units of area, it does NOT represent a physical area. So while the mental image of "higher chance of interaction = larger surface area" is simple, it's not always correct. There are other factors that can increase the chance of neutron capture, and those result in a bigger cross section, without changing the physical size of the nucleus.
In the case of xenon-135, it looks like there's still discussion of WHY the cross section is so high. Among other reasons, Xe-136 has 82 neutrons, which is a magic number, thus increasing the likelihood of capture. PianoDan (talk) 18:05, 5 September 2023 (UTC)[reply]
I knew it wasn't physical area but you can't make the cross-section bigger than the furthest possible capture I didn't realize those levels of fuzziness extended to such heavy particles. I suppose the thermal neutron is so slow compared to electron cloud electrons that its wavelength is still huge anyway. Sagittarian Milky Way (talk) 23:35, 5 September 2023 (UTC)[reply]
How did plants even go far as to evolve at an evolutionary pace comparable to such as certain extinct clades?
How did plants even go far as to evolve at an evolutionary pace comparable to such as certain extinct clades? Specifically, is there any basis to the theory that there was ever an alternative pathway through which the most diverse genus would have adapted in terms of different as well? Ассхол МакДелукс (talk) 03:52, 5 September 2023 (UTC)[reply]
I'm not sure there is any belief that plants evolved faster or slower than any other clades. Many plants are annuals, and even large trees can reproduce at a young age, especially if there has been an event that amounts to a selection pressure. Individual ramets or branches can sport at any time. So generation time shouldn't be a concern. Genome size (mostly from polyploidy) allows for "experimentation", so that's a wash too. Differences in mutation rates are a possibility, but those are more or less under the control of the organism, and selection is only purifying in important genes such as housekeeping genes. Abductive (reasoning)04:29, 5 September 2023 (UTC)[reply]
Units
Why does Atlantic and Pacific hurricane articles mostly use imperial units and Fahrenheit first? Why they don't use Celsius first on sea surface temperatures? Could this be changed?--40bus (talk) 15:48, 5 September 2023 (UTC)[reply]
The choice of primary units depends on the circumstances, and should respect the principle of "strong national ties", where applicable: In non-scientific articles with strong ties to the United States, the primary units are US customary.
I have reread Expansion of the universe for the nth time after clumsily trying to explain it to my kid, and realized I had, and have, bigger gaps in my knowledge than I had thought, and my questions make me feel like a child myself.
1. Shape of the universe notes "One of the unanswered questions about the universe is whether it is infinite or finite in extent", but how does this square with "its volume increased by a factor of at least 10^78" in the inflationary epoch? If the universe's spatial extent is infinite now, when was it not infinite such that it had a volume?
2. Shape of the universe also says that if the universe's extent is finite, it doesn't have an edge, because, what would be beyond the edge? It also name-drops maths, but is vague. Is that all we've got to demonstrate that the "raisin loaf" model is incorrect?
3. Expansion of the universe says gravitationally bound objects don't expand. Is this just relative to each other? If we observe from Earth two supergalaxies that are gravitationally bound, at the maximum distance those structures can be bound, and one is farther from us than the other, would we observe the distant one receding from us faster than the nearer one? If so, how do I square that with gravitationally bound structures "not expanding"?
4. Am I correct in believing that a 1-meter rod measured by me a billion years ago is still 1 meter today, and not 1.07 meters (Hubble's law)?
1. Picture a box in the Universe before inflation and watch what it does during inflation. You'll find that the volume of this box increases by 1078. And that is the same for all boxes in the Universe, even in an infinite one. (It would be nice to mark the box by something material. In the modern Universe one could use isolated galaxies or clusters of galaxies for that, but those weren't available during inflation).
2. Not sure what you're asking here, but a finite Universe is an analogue of the surface of a sphere or the surface of a torus (just one dimension higher), neither of which have an edge. Or think of the game pacman where, when you leave the screen at the right you enter the screen from the left. Now imagine the room you're sitting in was like that: you leave through one wall and come in through the opposite wall.
3. A cluster of galaxies is a gravitationally bound object; all galaxies in the cluster have the same cosmological redshift, i.e. recede at the same rate from us. (the measured redshifts differ because the galaxies are moving within the cluster and in addition to the cosmological redshift there is a component due to Doppler shift, but that's not immediately relevant to your question).
4. You're absolutely right. A rod is a bound object, held together by electromagnetic forces, so it is not expanding. To measure the length of the rod I suggest using a laser measurement, not another rod ;-) --Wrongfilter (talk) 22:44, 5 September 2023 (UTC)[reply]
Thank you!
1. I'm still having trouble, probably because the easiest, possibly lazy way to picture the Big Bang is a lot like an explosion. If the universe is infinite in its extent, does this mean upon the Big Bang occurring, suddenly an infinite universe exists, and expands like crazy for a while? Conversely, I had pictured all the universe's infinite matter and energy stuffed into a tiny volume, presumably measurable in its size, which then expanded somehow from a finite size to infinity (if, again, the universe's size is infinite). Lavaship (talk) 16:57, 6 September 2023 (UTC)[reply]
The Big Bang itself is difficult because we don't really know anything about it and we do not have the tools to make any very meaningful inferences about it. The earliest stage accessible to physics as we know it is a very dense, very hot state of the universe, finite or infinite. If it's finite early on it will stay finite forever after. Inflation did not start from the Big Bang but from an existing universe that just expanded very rapidly for a brief period of time. --Wrongfilter (talk) 17:54, 6 September 2023 (UTC)[reply]
:Regarding #1) the way to think of it is that the infinite universe began in a hot, dense state (not necessarily "smaller" just "everything packed closer together") and "expanding" means "space between the parts of the universe increases". The thought experiment known as Hilbert's infinite hotel is one way to imagine how an infinite, and densely packed, space can still expand to accomodate more space.
Regarding #2) In three dimensions, a sphere is finite in surface area, and yet has no edge. It's perfectly geometrically consistent to take that type of structure up a dimension. In 4-dimensional space-time, similar to a sphere being finite in 2D surface area, and yet edgeless, you can have a 4D hypersphere which is finite in 3D space, and yet edgeless.
Regarding #3) Metric expansion of space is only observable on the scale of galactic clusters. If a group of galaxies are close enough to each other to experience mutual gravitational attraction, the expansion of space happens through them, without affecting their distance. You only see the effect of the metric expansion of space larger than galactic clusters.
Regarding #4) Absolutely; gravity (the weakest of the fundamental forces) is already strong enough to overcome the forces exerted by the metric expansion of space. Thus, any objects held together by stronger forces (like the electromagnetic force which holds together solid objects) is definitely strong enough to overcome the paltry, weak force of the metric expansion of space. A solid rod will remain the same length forever. --Jayron32 13:13, 6 September 2023 (UTC) edit: Please ignore this answer. See below. --Jayron3215:21, 6 September 2023 (UTC)[reply]
It would be nice of you to acknowledge my responses instead of largely repeating them. We could have a discussion on the points where we differ (I think the statement "space expands through them" is meaningless, although that might be a philosophical point. In a fully relativistic treatment, the expansion does not exert a force; you could describe it as such if you use a Minkowski background metric.) but I ain't got no time for that. --Wrongfilter (talk) 13:57, 6 September 2023 (UTC)[reply]
No, you were correct to raise an objection. Clearly my links to other articles and additional information on matters such as 4D geometry and the nature of infinity were at best a distraction, and in most cases were legitimately incorrect. I thank you for setting me straight, and I apologize again for taking away from your otherwise sufficient answer. I will try to do better in the future. --Jayron3218:17, 6 September 2023 (UTC)[reply]
There are (deep breath) an infinite number of infinities. Further, those different infinities have different sizes; one infinity can be smaller that than another. I know, sounds wild but it's completely true. Good video on the subject on YouTube. So there's actually nothing weird at all about saying, the universe (maybe) is infinite in volume, and, this volume grew enormously. Yeah doesn't that stretch yer noggin a little? Reality is under no obligation to obey our human intuition, which is designed for surviving as subtropical/tropical plains apes.
A surface can be finite in extent, but have no "edge" or boundary. One of these is the thing we are both resting on right now: the surface of Earth. The Earth's surface is finite in area, but there is no edge of the Earth; it's the surface of a(n) (approximate) sphere. If you pick a direction and travel that way in a "straight line"—a great circle route, the route aircraft and ships attempt to stick to on long distance routes because this is the shortest distance between two points on the surface of a sphere, the curved surface equivalent of the notion of a straight line on a flat plane—eventually you come right back to the place you set out from. Really think about that for a moment. (Also no Columbus didn't prove this that is an 18th-century myth)
Yep, gravitationally-bound structures don't expand due to the expansion of the universe. Because, gravity binds them and holds them together, and completely overpowers this expansion. The expansion is observable in the huge intergalactic voids devoid of nearly all matter. Being almost entirely empty space, nothing there to resist the expansion. Not much matter to speak of, so not much gravity either.
So the further back in time we look—every telescope is a time machine, because light has only a finite speed and thus takes time to traverse space, so when we look across great distances we're looking back in time—the faster that galaxies are moving away from us, relative to ones closer in distance and thus time. Or restated, if space wasn't continuing to expand, all galaxies ought to be moving away from us at the same rate.
We really have no clue at present what exactly happened at the Big Bang itself. People have all kinds of hypotheses, but, they're just that, guesses basically, until we have ways to test and attempt to falsify them, because that's how we Do Science. All we can confidently say At The Very Beginning is, the universe was in a very (very) hot, very (very) dense state, and then expanded to a cooler, less dense state, thus eventually producing the state we observe it in today.
Chronology of the universe § The early universe: Once we reach a universe a mere 10−22 seconds (or, 0.000 000 000 000 000 000 001 s, please double-check me there) young, we start to understand things better, because the energies reach ones low enough that we can reach them in our biggest baddest particle accelerators, where we can make testable predictions using our physics theories and math and analyzing those predictions.
"a great circle route, the route aircraft and ships attempt to stick to on long distance routes" attempt is the keyword here. Defending upon a number of factors such as the jet stream and number of planes aircraft transatlantic routes vary day-by-day. Prevailing winds, meteorological conditions and ocean currents affect shipping to varying extents. so do landmasses and reefs, but that's blindingly obvious! Martin of Sheffield (talk) 17:20, 8 September 2023 (UTC)[reply]
At least, they do not need to factor in the expansion of the universe. This may become an issue in determining the optimal flight path in any future intergalactic exploration ventures. --Lambiam08:05, 9 September 2023 (UTC)[reply]
I've found this sentence here, "The tawa forest is affected by a cloud cap that forms above c. 400 m, causing increased precipitation" but I cannot seem to figure out what this 'c.' means. My first guess was sea level, but I can't find any evidence supporting this. I also thought that it could mean "cubic", but it doesn't seem to make any sense in this sentence. What does the 'c.' stand for?
MOS:CIRCA is about dates. And my experience ("in the wild", if you will) with "circa" has also been mostly (nearly entirely, actually) in reference to dates. This usage with a measurement seems decidedly weird to me. I would suggest changing to "approximately" in this case. --User:Khajidha (talk) (contributions) 14:05, 7 September 2023 (UTC)[reply]
I'm trying to find the original source of a physics thought experiment. That's the one in which two cars, same mass, same speed, collide frontally, compared to a car that collides with an unmovable, indeformable block. Somehow it seems pretty common among students of physics, but does not appear to have a name. Bumptump (talk) 16:51, 7 September 2023 (UTC)[reply]
It is an accurate model of a collison between two identical cars, and has been used since 1959 if not before. I'm not quite sure why a bog standard bit of Newtonian physics would have a name. Greglocock (talk) 22:43, 7 September 2023 (UTC)[reply]
Per Head-on_collision#Road_transportWhile it is true (via Galilean relativity) that a head-on crash between two vehicles traveling at 50 mph is equivalent to a moving vehicle running into a stationary one at 100 mph, it is clear from basic Newtonian Physics that if the stationary vehicle is replaced with a solid wall or other stationary near-immovable object such as a bridge abutment, then the equivalent collision is one in which the moving vehicle is only traveling at 50 mph., except for the case of a lighter car colliding with a heavier one.Shantavira|feed me08:27, 8 September 2023 (UTC)[reply]
The equivalence only holds perfectly if the cars are each other's mirror image, so if one has the steering wheel on the left, the other has it on the right. An observer should be unable to tell if there are two cars or one car and a gigantic mirror showing the mirror image. The equivalence then follows from the preservation of symmetry. We see the same with animals fighting their own mirror images. The animal cannot sense the difference between hitting an immovable mirror and each of its moves being perfectly copied and thereby parried by an opponent. --Lambiam07:40, 9 September 2023 (UTC)[reply]
A true mirror-image replica of the car you plan to crash is probably available at a high price and a long delivery time, mainly due to the unusual need for reversed items such as brand badge castings, contra-rotating engine parts and all the dashbord instruments including mirrored lettering on the retemodeeps. Philvoids (talk) 16:58, 10 September 2023 (UTC)[reply]
So which directions increase number and which decrease? Does Jupiter have so many cause it's big or has high Coriolis force or is hot inside or cold outside or thick skinned or some combination of that? Sagittarian Milky Way (talk) 12:31, 8 September 2023 (UTC)[reply]
I suspect that such convection cells are likely complex and chaotic behavior, likely obeying something akin to the Logistic map in terms of having islands of stability in the midst of otherwise chaotic behavior. --Jayron3213:29, 8 September 2023 (UTC)[reply]
I think that the number of cells is primary determined by ratio of the Coriolis force to the gravity acceleration. So, the fast rotators like Jupiter have many convective cells, while slow rotators like Venus and Titan have only one convective cell. Earth is somewhere in the middle. Ruslik_Zero20:32, 9 September 2023 (UTC)[reply]
The Coriolis force in turn depends on the spin rate of the planet and on the wind speed. When there's more heat to move from the equator to the poles (warm planet) or when less heat can be moved per cubic metre of atmosphere (thin air), the wind will be faster. Oceans may matter too: if there's an ocean with strong north-south currents, more heat can be transported by the oceans, so less will be transported by air. I think there could be planets where, due to continental drift affecting ocean currents, the atmosphere can alternate between multiple numbers of cells over geological timespans.
To find the number of convection cells on a particular planet (other than from observation), you may have to perform a full simulation with a model of ocean and atmosphere. Even then, you may find a bistable situation, where depending on history the circulation may be in either of two states. PiusImpavidus (talk) 10:18, 10 September 2023 (UTC)[reply]
Methamphetamine questions
Let me preface this by saying that I'm not asking for step-by-step instructions on how to make meth (I don't even smoke cigarettes any more), but I recently rewatched Breaking Bad (as you all should) and I was curious about a few things. Mainly with regards to accuracy - thought I'd bring it here.
1. How much would a methamphetamine chef *actually* make in the real world, on average?
2. Has there ever actually been an example of a huge secret meth lab that produces the stuff on an industrial scale, as seen with Gus Fring's lab?
3. Producing a 99% pure methamphetamine using the principal method used by Walter as shown in the show (phenylacetone and methylamine reaction) is apparently impossible in the real world - going from what I remember reading on forums and Reddit back in the day where chemists and actual former meth cooks were discussing this, something due to contamination with unwanted/useless isomers. That what is show in the show is pure science fiction. Is that still true? In the show it's kinda implied that Walter has found a way around this and no-one else knows how to do it, but it's never actually explained.
A friend has pointed out to me that, according to IMDB (not a Reliable source), the writers intentionally made Walter's portrayed method non-viable so that would-be criminals could not use it. {The poster formerly known as 87.81 230.195} 51.194.81.165 (talk) 18:39, 9 September 2023 (UTC)[reply]
Indeed. As a chemist, I absolutely love how the writers danced that fine line between "scientifically accurate depiction of how chemical synthesis is done" and "don't tell would be 'cooks' how to make meth." I honestly feel they did a fantastic job at it, down to little bits that we see in notebooks and the like. Oftentimes, as a chemist, I lose the ability to "suspend disbelief" because a show or movie does something blatantly wrong or impossible, such as in Wonder Woman, when the villains are described as making mustard gas much more potent by "replacing the sulfur atom with a hydrogen atom." They would have been better off just saying the villains had made a chemical weapon "ten times worse than mustard gas" and leaving it at that, without describing the method or change. A hydrogen atom literally cannot go in place of the sulfur and have the molecule stay together and do anything. When I watch Breaking Bad, the depictions are so faithful to real world chemistry and chemical engineering that I don't lose that suspension of disbelief. --OuroborosCobra (talk) 20:27, 9 September 2023 (UTC)[reply]
So (I suggest), by most definitions of Science Fiction (something that we SF fans have been debating for 90 years or so), Breaking Bad is not SF because it does not seek to use fictional or projected new science to show how this might change the World, but instead tries to portray the World as it actually is (with illegal Meth manufacture) and merely obfusticates some scientific detail so as not to facilitate real criminality. {The poster formerly known as 87.81.230.195} 51.194.81.165 (talk) 07:59, 10 September 2023 (UTC)[reply]
I mentioned "science fiction" because someone on a forum back in the day was saying that Walter's method of cooking meth and attaining a high purity (via that specific method - which is real, as far as I'm aware) was an example of such. TBH, I think the show itself lampshades that a little. There's a scene where Walt is chewing/mocking out one of the villain's henchmen who thinks that he can replicate Walt's formula because he's been watching him cook a few times, and pointing out that he really has no idea what the hell he's doing (compares him to a burger flipper, IIRC). Quoth him: "...if our reduction is not stereospecific, then how can our product be enantiomerically pure?". I was really just wondering if there was any actual method of doing this? I'm not asking for details of how to do it, just curious to get an answer to something that has been bugging me since I rewatched. Iloveparrots (talk) 00:28, 11 September 2023 (UTC)[reply]
My guess is this is sloppy journalism; there was another person named Marjorie R. Hingley who my google searches are showing was something of an expert in gastropods. I suspect (though cannot find any evidence of either) that the gastropod in question was named for Marjorie and not Lizzie. I can't find anything else, and the only google results I get that have both the name "hingley" and the word "gastropod" are 1) the specific little factoid on a few articles about Lizzie, and 2) several articles written by Marjorie R. Hingley. --Jayron3217:55, 11 September 2023 (UTC)[reply]
