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December 1

chimpanzees goes to war

I read once, I mean in de Waal, that a group of chimpanzees takes over a territory by killing one male of the other group after the other in the superior number. Does anyone know of any technical articles from behavioral research on this? 2A02:908:424:9D60:50B7:7FD9:2D61:8EF (talk) 08:02, 1 December 2022 (UTC)

Can you clarify please: are you asking for sources about how chimp cadres in territorial disputes will be most likely to attack isolated members of the other group? This is certainly a well-observed phenomena, and if that is what you are after, I can oblige, but before I go gathering links and references together, I'd like to make sure I have understood you correctly. SnowRise ^{let's rap} 09:54, 1 December 2022 (UTC)

Could you provide me a Source for the "This is certainly a well-observed phenomena"? Thank in Advance 2A02:908:424:9D60:50B7:7FD9:2D61:8EF (talk) 16:35, 1 December 2022 (UTC)

Any source that uses "phenomena" as a singular noun is hardly reliable. -- Jack of Oz ^{[pleasantries]} 20:42, 1 December 2022 (UTC)

A pointer: "Intercommunity interactions and killings in central chimpanzees (Pan troglodytes troglodytes) from Loango National Park, Gabon". This article is open access and has a long list of references.  --Lambiam 10:20, 1 December 2022 (UTC)

Intergroup Relations in Chimpanzees (2003) Michael L. Wilson and Richard W. Wrangham. Wilson seems to be a leader in this field, his work is quoted in a number of popular science articles like this and this. Alansplodge (talk) 12:41, 2 December 2022 (UTC)

December 2

Demand for unvaccinated blood?

My attention was drawn to a case [1][2] where donor-blood from non-covid-vaccinated people was demanded by anti-vaxxers. I quickly found that this wasn't the only case[3][4].

Is there any WP:RS coverage of such cases that predates covid? Gråbergs Gråa Sång (talk) 14:10, 2 December 2022 (UTC)

Not a lot. I did some date-limited google searches for information from 2019 and earlier, to avoid the Covid news, and I can't find much of anything. General Google, Google News. --Jayron32 14:20, 2 December 2022 (UTC)

There have been some similar ideas in the past, usually based on the idea that various intangible qualities of the donor would be transfused to the recipient. In addition to the Young blood transfusion idea, there have been all sorts of requests related to prejudice. The fundamental idea of Blood compatibility testing was developed in Europe by people who believed that Jewish and Aryan blood were medically different, and that being exposed to the other race's blood could "taint" not only yours, but also your future offspring.[5] It's not difficult to see how people jumped from "blood transfusion" to "bloodline".

The US Red Cross initially rejected Black blood donors during WWII, and then changed their policy to accept Black donors but to segregate the products and only provide them to Black soldiers. I remember the Jehovah's Witnesses, who oppose blood transfusions anyway, claiming in the 1980s that if the donor was gay, then the recipient might become gay, too. I would be surprised if these kinds of requests were not received here and there today. WhatamIdoing (talk) 17:43, 3 December 2022 (UTC)

The ignorance and beliefs behind such requests are certainly apparent in many parts of social media. Just yesterday here in Australia, where I like to think our education system is reasonably good, I had two people telling me that COVID vaccinated blood is just as bad for you as the vaccine itself. Telling them that I thought the vaccine was pretty good just sent them into conniptions. HiLo48 (talk) 23:49, 3 December 2022 (UTC)

Thanks for your input! I started this section: Vaccine_hesitancy#Blood_transfusion. Gråbergs Gråa Sång (talk) 14:03, 9 December 2022 (UTC)

Picture of Dr. Ben Carson

Howdy, My name is Warren Hector, and I need to help my grandson with a school project. We need to do a presentation of a famous American. We chose Dr. Ben Carson. Now we will start researching and writing but we also need to have a picture of him. Are you able to direct me to a place where I can print a color 8.5 X 11" picture of Dr. Carson? Thank you for your attention and help, Warren Hector 99.107.253.103 (talk) 16:36, 2 December 2022 (UTC)

Our article on Ben Carson holds a picture (public domain). Cookatoo.ergo.ZooM (talk) 16:41, 2 December 2022 (UTC)

link: File:Ben_Carson_official_portrait.jpg – dudhhr ^talk _contribs (he/they) 16:45, 2 December 2022 (UTC)

Hi IP editor. There are lots more available images on Commons at Commons:Category:Ben Carson Mike Turnbull (talk) 17:18, 2 December 2022 (UTC)

December 3

Antimatter bomb

Would one of those theoretical bombs that theoretically work by colliding antimatter with an equal amount of matter (assuming that anyone would be insane enough to build a bomb that would just blow up if it malfunctioned while in storage in the first place) produce radiation and fallout when it exploded? — Preceding unsigned comment added by 146.200.126.234 (talk) 23:23, 3 December 2022 (UTC)

Most energy would be released in the form of gamma rays and (anti-)muons, not as neutrons, which can activate surrounding materials, and there won't be fission products. So, a big flash of radiation when the bomb explodes, but not much fallout. I wouldn't say no fallout, but it won't be as bad as in current thermonuclear weapons. PiusImpavidus (talk) 10:15, 4 December 2022 (UTC)

What are we comparing? The theoretical explosive yield of 1 kg of ²³⁹Pu is about 75×10¹² J. That of 1 kg of antimatter is more like 180×10¹⁵ J, 2,500 times as much. The irradiation of not-annihilated matter will initially produce a substantial amount of quark–gluon plasma that, when it cools off, phase-transitions into baryonic matter of a composition I cannot guess, but which, AFAIK, may well be quite radioactive.  --Lambiam 13:00, 4 December 2022 (UTC)

December 4

is there a theoretical maximum size and weight for bird flight?

As I understand it, most of the largest flying birds are either predominantly gliders that can't sustain powered flight for long, or are bulky, mainly terrestrial chonkers that can fly just enough to get up into a tree and down again. With something like swans being the limit for sustained powered flight? Has anyone ever calculated a theoretical maxmum size and weight for flight? — Preceding unsigned comment added by 146.200.126.234 (talk) 00:56, 4 December 2022 (UTC)

If there is a theoretical maximum, the same theories would presumably apply to the pterosaurs, some of which were considerably larger than any flying bird. As for what the pterosaurs were capable of, see the discussion on the Quetzalcoatlus article: there seems to be considerable debate as to what this genus (the largest of the pterosaurs) were capable of. AndyTheGrump (talk) 01:58, 4 December 2022 (UTC)

I was under the impression that pterosaurs and pterodactyls used a different "design" when it came to flight? Also wasn't there more oxygen in the atmosphere in those days? 146.200.126.234 (talk) 02:24, 4 December 2022 (UTC)

It's a simple question of weight ratios. --Trovatore (talk) 04:00, 4 December 2022 (UTC)

If you simply scale up a flying creature, the required power to mass ratio increases with the square root of scale, which at some point must become a problem. Take-off speed also increases with the square root of scale. So as the bird gets bigger, the reserve power gets less, making the take-off run longer and reducing manoeuvrability until at some point it can no longer fly. Questions are, what drag coefficient can a bird reach? What power to mass ratio can a bird reach? What lift to drag ratio can a bird reach? Those numbers cannot be given very accurately, but it looks like swans and pelicans are close to the limit.

Pterosaurs had a more efficient design (reduced hind legs compared to birds reduced their mass, increasing power to mass ratio), so they could have been bigger than birds and still able to fly. A 20% increase in power to mass ratio already allows scaling up by 44%. But a lot about pterosaurs is unknown. We're not aware of entire groups of pterosaurs that had lost their wings, so presumably all species on the main branches of the pterosaur evolutionary tree could fly, but some, in particular large, species may have gone the way of the moa, developing island gigantism while loosing their ability to fly. Of most species, we haven't found complete wings, so it's hard to say if any particular species could fly. PiusImpavidus (talk) 11:21, 4 December 2022 (UTC)

See also Respiratory Evolution Facilitated the Origin of Pterosaur Flight and Aerial Gigantism (apparently pterosaurs were full of air). Alansplodge (talk) 12:07, 4 December 2022 (UTC)

Nature tends to push evolution to the limit. The largest flying birds today are the great albatrosses and the heaviest is the great bustard, so I think it's safe to assume those are the physical limits given the physiology of modern birds. Shantavira|^{feed me} 20:46, 4 December 2022 (UTC)

Moreover, it appears that in several families of large flying birds (albatrosses, bustards, swans, pelicans, vultures), the limit is always about 10–11 kg. That doesn't look like coincidence. PiusImpavidus (talk) 10:36, 5 December 2022 (UTC)

Perhaps heavier birds could exist if the atmosphere was denser. So for example if the Mediterranean Sea dried up, so that the there was air down to 4000 meters below sea level, a different constructed bird could be heavier. Graeme Bartlett (talk) 21:14, 4 December 2022 (UTC)

Assuming lift-to-drag ratio, power-to-mass ratio and drag coefficient stay the same, a simple calculation shows that the maximum scale is proportional to air density. Increase air density by 50% and we can have pelicans with 5.25 m wingspan and a mass of 35 kg, flying at the same speed as current pelicans. PiusImpavidus (talk) 10:36, 5 December 2022 (UTC)

Lift is proportional to wing area, which is proportional to the square of the length if the length to width remains the same. But, since birds have not evolved hollow wings, mass is proportional to the cube of length. Therefore, mass goes up faster than lift, so there must be a point where wing mass exceeds wing lift, and the bird cannot have a body and fly.

Man made airplanes are very large but the wing volume is mostly air. Dionne Court (talk) 03:29, 5 December 2022 (UTC)

Lift is also proportional to speed squared (until you hit the sound barrier), so the trick is to go faster. Man-made aeroplanes are much faster than birds. A Boeing 747-8 has a stall speed higher than the top speed of any bird in level flight. Power is speed times thrust and thrust is proportional to weight, so power-to-mass ratio matters. The Boeing 747-8 has a power-to-mass ratio during take-off of about 900 W/kg (190 W/kg effective power, as jet engines aren't very efficient at low speed), whereas few animals can get much above 12 W/kg for short bursts. Actually, it works out quite nicely. PiusImpavidus (talk) 10:36, 5 December 2022 (UTC)

This is also sort of interesting further reading:

Debunking the two-dimensional assumption on infinitely long wings, a 2018 conference paper at the Annual Meeting of the Fluid Dynamics division of the APS ...

More than once this year, I've engaged in fascinating discussions with very well-informed professionals on the topic of infinitely-long wings: if infinitely long wings are such a good idea - every extra meter of wingspan adds more lift than it weighs in structural mass - then, why not make airplane wings infinitely long? Well, the Boeing 777X already has wings that are sooooooooo looooooooong that the designers need to fold them to make room for the aircraft when it's at an airport.

It turns out that there are practical considerations - not the least of which relate to what to do with a very large wing while it's not flying.

Nimur (talk) 19:33, 5 December 2022 (UTC)

Radiation belts

Is there some kind of theory that explains which radius radiation belts occur at? Say about the Larmor radius? JoJo Eumerus mobile (main talk) 15:29, 4 December 2022 (UTC) JoJo Eumerus mobile (main talk) 15:29, 4 December 2022 (UTC)

Radiation belts are caused by the interaction of charged particles with a planet's magnetosphere. So the theory you're looking for is the overall theory of how planetary magnetic fields are generated and shaped. The Larmor radius refers to the shape of the orbit of a charged particle travelling in a uniform magnetic field, and on the scale of radiation belts, planetary magnetic fields are decidedly non-uniform. PianoDan (talk) 18:28, 4 December 2022 (UTC)

@PianoDan:I know how they originate, but what I wanted to know if there is some theory that says why a given belt occurs at a given distance. Jo-Jo Eumerus (talk) 17:16, 7 December 2022 (UTC)

Hyracodonts from the Ergilin Dzo Formation

What kind of Hyracodonts coexisted with Embolotherium andrewsi and Hyaenodon gigas? and what size and appearance did they have? CuddleKing1993 (talk) 18:39, 4 December 2022 (UTC)

December 5

Why is IC engine exhaust blue if it is burning oil?

I was having a debate with a guy over a truck engine that was emitting smoke. It was white, so I said it was unburnt fuel. If it was lube oil it would be blue, which he said was not necessarily so. Any book on engine repair will say blue indicates oil, but they don't say why - so it was kind of a she-said-he-said unprovable argument. Why does the presence of burnt lube oil in exhaust have a blue colour? Dionne Court (talk) 03:36, 5 December 2022 (UTC)

What matters is the size of the particles. Very small particles (smaller than the wavelength of light) scatter light following Rayleigh scattering. This mostly scatters blue light, so when viewing the smoke in sunlight against a dark background, it appears blue. When viewing it in transmission against a bright background, it appears brown. Larger particles cause scattering of light following Mie scattering, which has no preference for short wavelengths and therefore makes white smoke. Unless the particles in the smoke absorb certain wavelengths, which can lead to coloured smoke. Soot in particular leads to black smoke.

My suspicion (but nothing more than a suspicion) is that lubricant oil may pass through the engine without burning at all, making very small oil droplets and blue smoke. Fuel would partially burn, giving soot and black smoke. Water vapour or ash would give white or grey smoke. Funny chemicals may give smoke in funny colours, like orange or purple. PiusImpavidus (talk) 11:02, 5 December 2022 (UTC)

Those of us who work in the diesel engine industry generally associate blue exhaust with oil (burning lube oil). But there are some engine faults, such as damaged valves, and worn out injectors that cause white smoke, which is fuel mist. In some large engines (eg railway traction - see YouTube videos on locomotive cold starting), white "smoke" is emitted upon cold start cranking, until a cylinder fires, whereupon the exhaust turns black, until the engine warms up and fully burns its fuel and the exhaust becomes clear.

So, fully unburnt fuel gives a white exhaust. There may be other causes of white exhaust.

Now, lube oil has a vastly larger viscosity than diesel fuel. Wouldn't that mean that expelled oil droplets would be larger, and thus not be blue due to Rayleigh scattering? Dionne Court (talk) 01:11, 6 December 2022 (UTC)

Could humans somehow adapt to new planets / satellites (like Titan)?

Could humans somehow adapt to new planets / satellites (like Titan) with genetic functions like adaption to consume it's metan, plants, or maybe animals?

149.0.135.107 (talk) 19:25, 5 December 2022 (UTC)

I searched the archives of the journal Icarus - I mean, where else would we look, if we wanted a speculative but scientifically-informed viewpoint?

I used the search-query: human adaptation —

In lieu of a long-winded answer, let's go with "NO." Not even the optimistic scientists think that; if you're looking for an optimistic non-scientist, those people are a lot easier to find!

Nimur (talk) 20:11, 5 December 2022 (UTC)

The main way in which living organisms adapt to non-trivial changes in their environment is through the process of evolution. This will only work across several generations, and requires that (on the timescale of a generation) the changes are not too drastic. For example, the peoples living high up in the Andes mountains or the Himalayas are genetically adapted to the low oxygen levels there. It seems a sure bet that in the not too far future far-reaching adaptations will become technically possible through genetic engineering, and for example adaptation to life under water is a stock theme in science fiction. However, the conditions elsewhere in our solar system, as soon as you leave Earth's biosphere, are so radically different in almost all respects from what is needed for human metabolic homeostasis that even extensive genetic engineering offers no plausible path. Human life outside the protection of Mother Earth will require maintaining a bubble with Earth-like conditions at all times.  --Lambiam 01:20, 6 December 2022 (UTC)

For interest, if not real-world relevance, the term traditionally used in science fiction for physically adapting humans to non-terrestrial conditions is Pantropy. {The poster formerly known as 87.81.230.195} 176.249.29.80 (talk) 03:46, 6 December 2022 (UTC)

Just for completeness, the main way that humans adapt to their environment is technology, the evolution of which occurs on much shorter time scales than biological evolution. --Jayron32 19:26, 6 December 2022 (UTC)

Pedantic nitpick: technology is when we humans adapt the environment to us. Adapting humans to an environment would be a non-existent sci-fi level genetic engineering technology. Bumptump (talk) 01:21, 7 December 2022 (UTC)

Not necessarily. Humans alter the environment with technology, but they also use technology in ways that does not alter the environment. A space suit, for example, does basically nothing to the space around the astronaut, but still uses technology to allow the human to adapt to the environment of space. Humans do also adapt the environment (see, for example, Anthropocene), but that is not what I was referring to. --Jayron32 14:15, 7 December 2022 (UTC)

metan? oh, methane. —Tamfang (talk) 05:33, 8 December 2022 (UTC)

How big was Ardynia praecox?

I really want to know how big was Ardynia praecox. CuddleKing1993 (talk) 21:00, 5 December 2022 (UTC)

That's nice. This paper has a picture of a lower jaw of Ardynia praecox, length is some 10 cm. Nothing other than jaw and skull bones seem to be extant (but what do I know...), so you'll have to take it from there. --Wrongfilter (talk) 21:16, 5 December 2022 (UTC)

I wanted to know if Ardynia praecox was the same size as Hyracodon nebraskensis, was the lower jaw of Hyracodon nebraskensis 10 cm? CuddleKing1993 (talk) 21:28, 5 December 2022 (UTC)

You figure it out from this picture, which says the piece of Hyracodon is 2.67 inches (6.8 cm). --jpgordon^{𝄢𝄆𝄐𝄇} 23:45, 6 December 2022 (UTC)

December 6

If a woman instantly turned to vacuum in my arms would my eardrums break?

I know it's impossible but it should be a fairly simple physics problem. What would be peak decibels at the ear? How far away could the implosion be heard? Would I be physically injured and how bad? Sagittarian Milky Way (talk) 17:53, 6 December 2022 (UTC)

This is not necessarily a simple problem, and also, why are you asking this? Like, really, why do you want other people to take their time answering you a question you know to literally be impossible like if a woman instantly turned to vacuum in my arms would my eardrums break? Normally, I'm all for a fun thought experiment, but this is something you are asking other people to spend time figuring out. Can you at least tell us why first? If nothing else, it might help simplify the parameters of the question, which are anything but simple. --OuroborosCobra (talk) 18:11, 6 December 2022 (UTC)

https://what-if.xkcd.com/6/ and being interested in science fiction/fantasy including teleportation. I think I also once made a joke about this before teleporting in RuneScape (yo everyone clear a 20 meter radius for the implosion I'm gonna teleport) Sagittarian Milky Way (talk) 21:25, 6 December 2022 (UTC)

If you're going to invent a magic world where normal physics doesn't apply, it doesn't matter what would happen, because you've already thrown physics out the window. It's your magical invented world, you come up with an answer to your question. --Jayron32 18:17, 6 December 2022 (UTC)

That's a bit flip, Jayron. You could use that sort of rhetorical technique to dismiss pretty much any counterfactual. There are some extremist philosophers who do just that, but I don't think most of us would want to follow them; counterfactuals seem to be essential to human thought.

In this case it's pretty clear what it means: Set up a system that's like normal ambient conditions, with SMW standing in front of a woman-sized-and-shaped hole in the air, and evolve the system according to the usual equations.

The analysis below is in the right direction, but just computing the energy doesn't necessarily tell you much about the amount of damage it could do. 6 kJ of a high explosive will break a lot of stuff, but my intuition is that this situation won't have much brisance.

A detailed answer would be in the domain of computational fluid dynamics (which, by the way, is hard). --Trovatore (talk) 19:51, 7 December 2022 (UTC)

Yeah, I would've guessed at least a sphere in a sphere of air in a thin airtight sphere of kilogram prototype-material in an otherwise empty universe is determinable to plus or minus ≤10 decibels for a point not too close to the pressure vessel but what do I know, maybe even that's still too complex for a supercomputer to deterministically model. Sagittarian Milky Way (talk) 17:57, 8 December 2022 (UTC)

You could work out the energy involved, say 60 litres × 100000 Pascals ie 6 kiloJoules. Also exposing one side of a human body to a vacuum is not a good idea! There is going to be a force of body-exposed area × air pressure. perhaps 0.25×100000 =25000 Newtons (like a weight of 2.5 tons). Expect some damage. Graeme Bartlett (talk) 22:16, 6 December 2022 (UTC)

I didn't even realize you could multiply Pascals and 0.06 cubic meters like that. Metric is awesome! If asked for the Joules of 60 liters of STP imploding full vacuum on a test I'd bubble in 6 kJ and hope for the best but I would not be confident at all. Sagittarian Milky Way (talk) 17:57, 8 December 2022 (UTC)

The level of force means little, as it will only appear for a small time, before the vacuum is rapidly filled. For funsies (don’t judge me) I looked up this slow-motion video of a bouncing ball to estimate the force during the rebound. It turns out that it is roughly eight times your scary 2.5kN. Getting hit by a large rubber ball is certainly painful, but such incidents are routine during PE classes (see: football, handball, etc.) and rarely lead to serious injury.

Math: the video uploader said the ball is 85mm in diameter. It takes ~7ms to move a distance equal to its diameter, assuming a restitution coefficient of 1 for simplicity its vertical speed varies from -12 m/s to +12 m/s. It also takes roughly 7ms to rebound [from timestamps 12.3ms to 19.3ms] (this may not be a coincidence), so its average acceleration during the rebound is $a=\Delta V/\Delta t=24/0.007=8.10^{3}m/s^{2}$. Assuming a density of $\rho =1000kg/m^{3}$, its weight is $m={\frac {4}{3}}\pi R^{2}\rho =2.6kg$. Then by Newton’s second law $F=ma=21kN$.

The energy calculation is more meaningful. Assuming an implosion (air getting sucked in) has roughly the same detrimental effects as an explosion (air getting pushed out), one can compare the 60kJ of magical implosion with some sort of combustion. It’s about 15g of TNT equivalent, for instance, but I assume few people are familiar with explosives.

Here’s another comparison: a relatively common effect for stage magic is the rapid burning of nitrocellulose (which has a quick and ash-less combustion). For instance, the magician sets on fire one end of a rope, the rope burns quickly and turns into a solid cane (or a dove, or...). The "flash rope burning" effect is about 450kJ, or 7.5 times as much as the "real magic vanishing lady" one, and it certainly does not kill the magician.

Math: assume a "flash ribbon" of length 1m and cross-section 10mm^2, made out of pure nitrocellulose of density 0.77g/cm^3 so roughly 77g in weight. The enthalpy of combustion of nitrocellulose is surprisingly hard to find online, but this 1950 paper gives values between 1,400 calories per gram (5.9 kJ/g) and 4,100 calories per gram (17 kJ/g). Let’s take the lower value for simplicity, that is about 450kJ for my flash paper sheet.</math> Tigraan^{Click here for my talk page ("private" contact)} 15:27, 7 December 2022 (UTC)

-12 to +12 in 7 ms is ~3428.57143 meters per second per second. And a water density ball that fits in a liter cube can't be more than about half kilogram. Also the sphere volume formula has a 3 exponent not 2. And a 10x1x1000 ribbon of 0.77 density would weigh only 7.7 grams. Also 7.7 grams of modern gunpowder (chemically similar to flash paper) in a gun is a lot louder than 7.7 g of unconfined flash paper ribbon lit at one end (or 7.7 g's of candle, TNT actually has less Joules per gram than most fuels). A vacuum rising to ambient is also much fewer Pascals than peak gun pressure falling to ambient but Joules isn't the only factor. Sagittarian Milky Way (talk) 17:57, 8 December 2022 (UTC)

The creation of a true vacuum will trigger false vacuum decay. Poof lady, poof Milky Way, poof universe...  --Lambiam 20:41, 7 December 2022 (UTC)

Isn't that just a hypothesis? And would it even be possible for future technology to tell? If it kills everything in a sphere expanding at the speed of light no one would ever know (unless there's an afterlife) and if it hasn't happened yet is it possible to prove or disprove a lower state exists without causing it? Sagittarian Milky Way (talk) 17:57, 8 December 2022 (UTC)

As far as we know, and with our current theoretical understanding, it is possible that our current vacua are false. Yet we cannot quantify the likelihood of this possibility, nor the likelihood of spontaneous decay. And, finally, it is not even known whether the consequences of such decay will have a universal effect or will remain localized and be temporary.  --Lambiam 21:29, 8 December 2022 (UTC)

If that happened, wouldn't the surrounding air immediately fill the evacuated space? ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:15, 9 December 2022 (UTC)

December 7

Can you have an electromagnetic pulse without a planetary magnetic field?

(Electromagnetic pulse) Say on Venus, Mars or Titan. JoJo Eumerus mobile (main talk) 20:14, 7 December 2022 (UTC)

Yes. --OuroborosCobra (talk) 22:38, 7 December 2022 (UTC)

EMPs caused by lightning can occur on planets with an atmosphere, such as Venus. The EMP carried by a powerful coronal mass ejection can certainly impact all inner planets but will not cause a magnetic storm on those without magnetosphere. BTW, Titan's orbit skirts Saturn's magnetosphere, and a magnetic storm on Saturn might have a minor influence there.  --Lambiam 03:57, 8 December 2022 (UTC)

Are there any papers or books discussing such a non-magnetic EMP? Jo-Jo Eumerus (talk) 10:53, 8 December 2022 (UTC)

EMP stands for electromagnetic pulse; they are as magnetic as it gets with pulses. Various types, distinguished by what causes them, are discussed in our article on this topic, which you linked to in the question.  --Lambiam 12:04, 8 December 2022 (UTC)

Just to clarify, electromagnetism is one thing. If you have moving electrical charges, you're going to have a magnetic field. If you have a magnetic field, there's a moving charge of some sort. Insofar as lightning is an electric current, it will generate a magnetic field. --Jayron32 13:08, 8 December 2022 (UTC)

Sorry, should have said "EMP on a body w/o an intrinsic magnetic field". Jo-Jo Eumerus (talk) 15:11, 8 December 2022 (UTC)

@Jo-Jo Eumerus:, you seem to be under a false impression of some sort, though I'm not entirely sure what. The existence of magnets, magnetism, and magnetic fields does not depend upon a planet having a magnetic field. If you take a permanent magnet from Earth and take it to Mars, it will still be a magnet and still have a magnetic field. If you take an electromagnet to Mars and turn it own (moving electrical charges through it), you will have a magnetic field. Second, an EMP is not a pulse of or through a planetary magnetic field. If you detonate a nuke on Mars, you will have an EMP. It's being generated by the nuke itself, and not an interaction with a planetary magnetic field. To put it another way, water is still wet on Mars, as it being wet is a property of water, and not the planet it is on. In either case, the existence (or absence) of "a body" with "an intrinsic magnetic field." --OuroborosCobra (talk) 14:59, 8 December 2022 (UTC)

As listed in the linked article, there are many kinds of electromagnetic pulses, differing in strength, spectrum, polarisation and cause. A nuclear electromagnetic pulse caused by a high-altitude nuclear detonation like the Starfish Prime test has a lot to do with the planetary magnetic field. It's horizontally polarised and very fast (nanoseconds). Your average nuclear detonation at ground level also causes an EMP, much weaker, and vertically polarised. That pulse doesn't depend on the magnetic field. A coronal mass ejection hitting the Earth's magnetosphere can cause a geomagnetic storm, a kind of EMP over a billion times slower than the nuclear kind (seconds to minutes) and with completely different effects. That pulse also depends on a planetary magnetic field. A lightning strike makes a pulse on an intermediate timescale (milliseconds) and doesn't depend on the planetary magnetic field. PiusImpavidus (talk) 17:14, 8 December 2022 (UTC)

Sugar solubility in sodium chloride solutions

What data are available re the solubility of sucrose in sodium chloride solutions of various salt content up to saturation in salt, compared to the solubility of sucrose in pure water? Is there salting-in or salting-out? 178.138.99.84 (talk) 23:53, 7 December 2022 (UTC)

"It's complicated as hell." See:

• Seidell, Atherton (1919). Solubilities of Inorganic and Organic Compounds. p. 694.

for a table of "solubility of sugar in aqueous salt solutions at 30°, 50°, and 70°". It in turn is cited to original data from page 313 of:

• Schukow, Iwan (1900). "On the influence of temperature on the solubility of the sugar in solutions of non sugars". Zeitschrift des Vereines der Deutschen Zucker-Industrie. 50: 291–321.

Wow, that was a fun fragment of a ref to decipher and trace! I think there may be a sub-title to that journal, as it has merged and split several times. DMacks (talk) 02:15, 8 December 2022 (UTC)

So, diving down a rabbit-hole, I could find only limited information about Schukow, so we won't get a new bio article from him. Apparently he was involved with the Association of Russian Sugar Manufacturers. I found proceedings of a 1906 meeting he attended where others were discussing ongoing development and validation of a fancy then-new test called Fehling's solution. That discussion also mentioned the name Violett in connection with that sort of reagent, but I'm at a dead-end finding any further info in that direction. Does anyone know if Violett is someone who involved with Fehling's (but whose name fell out of eponymous use) or if it is a different reagent that has itself long become obsolete? DMacks (talk) 05:08, 8 December 2022 (UTC)

The Ukrainian and Russian Wikipedias each have an article on Ivan Diomydovych Zhukov: uk:Жуков Іван Діомидович and ru:Жуков, Иван Диомидович.  --Lambiam 11:53, 8 December 2022 (UTC)

Thanks! Anglicizing those names from older literature makes my brain hurt. DMacks (talk) 16:59, 8 December 2022 (UTC)

It is not a matter of age, but merely of a different method of Romanization for German as the target language. "Our" Georgy Konstantinovich Zhukov is Georgi Konstantinowitsch Schukow on the German Wikipedia.  --Lambiam 21:16, 8 December 2022 (UTC)

December 8

Water boiled twice

I've heard that water tastes different after being boiled a second time because all dissolved oxygen has been boiled off. Is there any truth to that? 31.217.44.13 (talk) 05:07, 8 December 2022 (UTC)

Why don't you try it for yourself, and report your findings here? ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:33, 8 December 2022 (UTC)

Fortunately, somebody has already done that, see:

Quality change mechanism and drinking safety of repeatedly-boiled water and prolonged-boil water: a comparative study, which says:

The quality changes of RBW [repeatedly-boiled water] and PBW [prolonged-boil water] show very similar trends that are not as great as might be imagined, and both are impacted by the tap water quality and the physiochemical effects. The dominating physiochemical effects are the water evaporation and the resulting concentration of unreactive components (most dissolved components), which can be easily explained by the existing evaporation-concentration theory.

So any slight change in taste is due to the concentration of minerals and other impurities, caused by evaporation.

Alansplodge (talk) 12:16, 8 December 2022 (UTC)

• See this previous question: Wikipedia:Reference desk/Archives/Science/2010 February 23#Making tea with zingless water. -- Jack of Oz ^{[pleasantries]} 19:50, 8 December 2022 (UTC)

Well remembered Jack. It comes to a similar conclusion but without citing a source. Alansplodge (talk) 22:20, 8 December 2022 (UTC)

That's pretty interesting! I can't see any difference in taste but have always thrown it out because boiling the second time won't produce bubbles but dislodges lime chunks. Tap water is very hard here (tastes like evian) but not chlorinated, still I'd rather not get chunks of carbonate in my food & drink (its taste doesn't go well with anything). 31.217.44.13 (talk) 15:15, 9 December 2022 (UTC)

Implausible sung note

Our article on Tim Storms alleges that he has sung a note of G₋₇, or 0.189 Hz, at which pitch it would need "more than five seconds for the vocal cords to oscillate once".

I'm curious in what sense this can be said to be "singing". What if I just breathe in for 2.5 seconds and out for the same length of time? Am I not generating 0.2 Hz pressure waves, at very low intensity to be sure, but probably more than Storms is getting from his vocal folds? And given that he has time to consciously reshape his larynx during a single cycle, why couldn't anyone do that?

I suspect there's some sense in which the claim is meaningful, but I'm having trouble figuring out what it could be. --Trovatore (talk) 16:35, 8 December 2022 (UTC)

I agree. A 0.2 Hz sound isn't a note, it's percussion. You generate a sound like that merely by hitting a drum every 5 seconds. The effect on the listener would not be a note, but of slowly repeated pulses. Even in the case of a long attack and decay, such a sound would not be recognizable as a pitch. The relationship between rhythm and pitch (which is to say that pitch is just rhythm sped up) is demonstrated to great effect in this video starting at 4:23 by Adam Neely during a lecture he gave a few years back. 12 bpm is even fantastically slow for a practical rhythm, Neely himself makes the case that 33 bpm is the slowest reasonable rhythm for anything described as music. See [6]. --Jayron32 16:46, 8 December 2022 (UTC)

Why is it that if a robot pops bubble wrap at precisely 1,201 beats per minute it makes a continuous note (at least if the bubble to left ear and bubble to right ear travel times are two constants x and y) but the inventor of the sea clock could hear second ticks weren't simultaneous till they were ≤0.02 seconds apart? He'd keep a prototype on each side of the door in the winter to test how long it took the cold one to drift 1 second and in the middle 96/100ths of this time he could tell it didn't sound like when it was simultaneous. Sagittarian Milky Way (talk) 23:57, 8 December 2022 (UTC)

These are quite different scenarios. They can coexist. One is about a rapid steady repetition being perceived as a tone, a quality of the sound. (Does the number 1,201 have a particular significance, or might you as well have written 20 Hz?) The other is about limitations in perceiving differences. What makes you think that this coexistence is in need of an explanation?  --Lambiam 05:02, 9 December 2022 (UTC)

SMW: If you watch the Neely videos like I told you, he actually demonstrates it. In the range between about 10-20 Hz, the sound becomes "confused" and people have a functionally hard time distinguishing between pitch and rhythm. It also is not a hard limit across humanity. In those ranges, different people will "hear" different things depending on factors entirely unique to themselves; but generally pulses below 10 Hz generally are perceived as individual beats (rhythm) and generally pulses above 20 Hz are perceived as pitch, but these are not hard-and-fast. This also depends on the exact characteristics of the sound wave in complex ways. A sawtooth wave and a square wave and a sinusoidal wave will all probably have distinctly different ranges over which they get perceived as separate pulses vs. pitches. Also also, there is a complex perceptive relationship between amplitude and frequency and perceived loudness; generally higher pitched sounds are perceived as higher in volume for the same actual amplitude waves; this is why infrasound is a thing. If you take a note at a certain consistent amplitude, and lower the pitch, it becomes progressively quieter and quieter until it becomes inaudible. Infrasound of the same amplitude as most audible pitches is inaudible to most human ears. If you raise the volume on those sounds, however, to the point where we can hear them, they will sound like individual pulses rather than as a distinct pitch; at least until about the 10 Hz limit... after which it becomes confusing until about 20 Hz. --Jayron32 12:58, 9 December 2022 (UTC)

I can sing at 1.6 μHz, but when I tried to demonstrate that to the Guinness Book of World Records judges, they got impatient and left even before I had gone through the first cycle.  --Lambiam 05:08, 9 December 2022 (UTC)

In acoustics, we have the concept of timbre. A musical note is embodied by a complex sound wave carrying energy at many frequencies, with one prominent fundamental frequency. Perhaps non-obviously, the fundamental frequency need not be the most energetic: if we plot the spectrogram for most musical instruments (and especially for the human voice), we can easily see that even a simple note has many frequencies. We have technical words for some of these aspects: overtones, timbre, resonance, and so on. But it's complicated - it's worthy of an entire library full of explanatory books.

To try to make some sense of it, Here's Fundamental Frequencies, part of the Real Simple Project in computational acoustics at CCRMA, "devoted to the development of musical acoustics laboratory exercises integrating both hands-on laboratory experience and computer-based simulation." If you want to play with Fourier analysis of musical tones, this website provides great resources at zero cost - and it ramps up in mathematical complexity to serve the needs of even the most mathematically analytical signal-processing and music enthusiast!

Just to layer on some complexity, there exist plenty of situations where the sound wave contains zero energy at its fundamental frequency - for certain defintions of the fundamental frequency - because the fundamental frequency can be defined using the spacing of the harmonics, rather than the value of the lowest harmonic. This means that the fundamental need not be the lowest frequency that contains energy, either! This stuff isn't only theoretical nonsense - it has a lot to do with how a human perceives the musical note embodied in a complex waveform. (This was demonstrated as a sort of party-trick during a recent episode of QI: identical complex tones were played, and the panelists were asked which notes sounded higher - when in fact this was a soundwave with frequencies specifically constructed to create an ill-posed question!

For "very low frequency" signals - one of my personal favorite topics - the theory can be quite clear, but the signal can be very muddy!

Nimur (talk) 16:30, 9 December 2022 (UTC)