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August 11

Parrots and cuttlefish bones

Pet parrots are often provided with a cuttlebone as both a source of calcium, a beak sharpener/conditioning tool and just as something to pull apart in general. My parrot (goffin) really seems to love the texture of it - the way it collapses when squeezed hard.

I was wondering - what (if anything) do wild parrots use for this purpose? 146.200.127.77 (talk) 06:46, 11 August 2022 (UTC)

You might have come up with a possible explanation for why wild cockatoos, most often sulphur-crested cockatoos, in Australia attack timber parts of houses and some plants. HiLo48 (talk) 07:54, 11 August 2022 (UTC)

Could be analogous to indoor cats which are given scratching posts, lacking natural tree trunks in most houses. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:00, 11 August 2022 (UTC)

In the wild, the diets of most Parrots include tough nuts and seeds which their beaks have evolved to deal with. Although pet parrots are (hopefully) also fed with such items, these will likely form a lower proportion of their diets due to softer foods also being supplied, so they need to perform supplementary chewing that reduces the discomfort of beak overgrowth.

Since in the wild beak under-growth would be a problem, parrots' beaks probably naturally grow a little more than on average is necessary, and they probably also correct this by supplementary chewing. Possibly "urban parrots" are also feeding partly on human-discarded (or deliberately offered) foodstuffs softer than their 'natural' diet, so have to perform more of this beak maintenance. {The poster formerly known as 87.81.230.195} 90.196.45.159 (talk) 21:42, 11 August 2022 (UTC)

August 12

Spiral galaxy

Recently I was watching a PBS entry on the subject of the Milky Way and on galaxies in general. One question that I can't find a concrete answer to is what is it that determines the direction of the spin of a spiral galaxy? If you make a rough analogy with a hurricane, the direction of spin is determined by the direction of the earth's rotation, i.e. by external forces. So are there external forces acting on galaxies which influence which direction they spin? Or is it just the net effect of all manner of random gravitational pulls within the galaxy? Or both? (Maybe the article explains it, but I'm as dense as a neutron star so I might have overlooked it.) ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:51, 12 August 2022 (UTC)

While not directly answering your question, it seems that observations of spin direction show marked asymmetry - see discussion here. Mikenorton (talk) 21:17, 12 August 2022 (UTC)

(It's always fun to read up on astronomy articles and see how outdated my understanding is.) There's a couple distinct concepts in spiral galaxies: the oribts of stars around a general galactic center, which is separate from the rotation of spiral arms (and of course there's plenty of other motions in galaxies too, but those are the two you're asking about). The first concept is that if you were to take a naive model of a flat disk galaxy and say that all the stars orbit around a dense center similar to how planets orbit around a star, then by simply looking at Kepler's third law for a little while you'd see that even if you started with stars grouped in spiral arms, they'd quickly dissipate (differential rotation or the "wrapping problem"). But there's a kicker in that if you look at how stars orbit a galaxy (the galaxy rotation curve), it doesn't neatly behave as if they were all following Kepler's laws and Newtonian gravity, and that's due to the dark matter halo (or at least that's how the effects of observed invisible mass effects are currently conceptualized -- dark matter itself is not yet understood). But dark matter would not be enough to stabilize spiral arms either, and while I've seen alternative models thrown around, the essential takeaway is that spiral arms are not a function of the orbits of stars themselves, but of star formation, which is catalyzed by enormous dense clouds of gas. In both models of spiral arms featured in the spiral galaxy article (of which I'm only really somewhat familiar with density wave theory) the spiral arms are a propagation of areas of high gas density, which trigger formation of massive, hot, and short-lived stars -- more importantly in other models the activity of these stars and the tendency to supernova is essential to the propagation of the spiral arms as well. At the end of the day the apparent pattern rotation of the spiral arms will be much slower than that of the individual stars.

Now, where does the original rotation, the angular momentum, come from? Well this is where I find out my astrophysics knowledge is outdated, because it looks like people no longer like the top-down models of galaxy formation, in which you have giant clouds of gas collapsing into smaller clouds that individually collapse into stars -- the kicker being that any tiny amount of net angular momentum in your giant cloud starts to appear to magnify in terms of angular velocities as the cloud collapses, similar to say a skater or dancer spinning faster as they pull in their arms/legs -- this also causes the initially spherical-ish cloud to flatten out like a wad of pizza dough. The bottom-up models by contrast works by collisions of smaller bodies, of which I have seen many simulations forming pretty spiral shapes (and residual angular momentum just like if you imagine taking two adhesive billiard balls and knocking them into each other at an angle, they'll stick and continue to spin together -- ok, not an everyday occurrence, but I'm sure you've seen paired figure skaters do something similar where one grabs their partner skating in at a skew and they start spinning, no additional application of force required), but those were pretty primitive simulations at the time, so they've obviously gotten a lot better. (Here's a decent some-astronomy-class-level non-math overview of models of galaxy formation.) It's all detailed with more pretty pictures in the galaxy formation article linked. Hopefully this answer didn't get too long and just repeat what's in the articles. SamuelRiv (talk) 22:21, 12 August 2022 (UTC)

The initial direction of spin is, as far as I know, just believed to be random, just as it is with star systems. Once this gets established, it's "locked-in". Everything subject to the system's gravitational effect is going to be induced to orbit in the same direction and aligned with the same plane, unless lots of energy winds up changing that, because the gravitation of everything in the system will tug it in that direction. In our own Solar System, see Uranus, which spins "on its side", with its poles almost perpendicular to the ecliptic, unlike pretty much everything else in the Solar System. Generally this is believed to be the result of one or more giant impacts in its history that flipped it, just as Earth's axial tilt is believed to be the result of an impact that formed the Moon. At the scale of the whole universe, the prevailing theory holds that its large-scale structure is random, the result of randomness at the quantum scale that then got "blown up" massively in size as the universe expanded due to cosmic inflation. This resulted in the initial distribution of stuff post-inflation, and since then the universe has just been evolving under primarily the influence of gravity. --47.147.118.55 (talk) 05:09, 14 August 2022 (UTC)

So current thinking is that it's random. Good enough. Thank you all. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:04, 16 August 2022 (UTC)

In the broadest sense, the universe is largely uniform with small anisotropies. If there were a net angular momentum in the universe (so if the expanding universe with all the random galaxy collisions had an ever-so-slight preference for which way everyone started moving or spinning at the end of the day), then our fundamental understanding of how the universe and physics works would be changed, because that means that there's a preferred direction in space. (This wouldn't necessarily be catastrophic -- there's (apparently) a preferred direction in time (different but sorta similar idea), and possibly in neutrino handedness and some other particle physics quantities -- but it'd be mega-mclarge-huge.) SamuelRiv (talk) 04:25, 16 August 2022 (UTC)

Resolved

August 13

Why doesn't Britain grow berries that are well known in Finland?

Hi Wikipedia. I'm a Brit. Earlier today I went picking some blackberries: free delicious food. In the past I've spent some time in Finland, where they are familiar with berries like the cloudberry, lingonberry, and sea buckthorn berry. But I've never encountered any of those three berries in Britain, not on a bush, not in a restaurant, not even mentioned or named by anybody ever. Why is this? I would imagine that Finn berries could grow in Britain (fairly similar climate; not like trying to grow a banana). Equinox ◑ 02:38, 13 August 2022 (UTC)

Sea buckthorn grows in parts of southern Britain, but isn't common and certainly isn't commonly eaten; cloudberry is even rarer, and lingonberry is not native as far as I can discover. There are two aspects to the question: why aren't these plants more common in Britain, and why aren't they eaten (since importation of foreign fruits is commonplace)?

One factor is that during the last ice age (and, yeah, we're really still in it, this is just an interglacial) most of future Britain (and NW Europe) was ice-covered, and after the ice melted plants and animals had to (re)colonise the land from continental refuges. This was not a speedy process, and Britain was cut off by the formation of the English channel quite early on, before some species could get that far at all, or in numbers that could compete well with rivals.

Another factor is that in Britain agriculture and forest (etc.) clearance to accommodate it began a few thousand years ago (and the neolithic/copper/bronze/iron age populations were, we are beginning to realise, much bigger than we once thought), eliminating much of the habitats that such plants require: by contrast Finland (which I've all-too-briefly visited) has remained mostly forested (etc.) right up to the present, so these plants have always been and continue to be more readily available from the wild, and are now cultivated.

This in turn means that the consumption of such berries has persisted in Finnish culture (and others), whereas it never became part of (or was long-ago dropped from) traditional British cuisine. It could be promoted (if anyone wanted to do so) and might or might not catch on, but this borders on the vagaries of fashion, for which there are no easy explanations or predictions. {The poster formerly known as 87.81.230.195} 90.196.45.159 (talk) 05:43, 13 August 2022 (UTC)

Thank you for this thoughtful answer! (Admins please ban this user, it's not allowed to be an IP and have an opinion.) Could you elaborate a little on British agriculture doing clearance "a few thousand years ago": who did this and why? Not the post-mediaeval "enclosure" we usually complain about. Equinox ◑ 05:57, 13 August 2022 (UTC)

I assume that's a reference to the Neolithic Revolution? Shantavira|^{feed me} 09:04, 13 August 2022 (UTC)

This article quotes Oliver Rackham who dates the main clearances in England to the Bronze Age;

Much of England had been cleared as early as 1000 BCE... The Bronze Age saw intensive farming on a scale that we are only just beginning to appreciate... Rackham describes the immense clearance undertaken during the Bronze Age, boldly claiming that ‘to convert millions of acres of wildwood into farmland was unquestionably the greatest achievement of any of our ancestors’. He reminds us how difficult it was to clear the woodland, as most British species are difficult to kill: they will not burn and they grow again after felling.

Alansplodge (talk) 10:36, 13 August 2022 (UTC)

Here's a preview of Rackham's book quoted above: The History of the Countryside (2020). Alansplodge (talk) 11:03, 13 August 2022 (UTC)

Also note that bilberries, picked by hand from the hills, are still sold in supermarkets in the North of England, [1] but are unheard of in the South, where we consume many tons of its close relative, the blueberry, which has to be flown in from America. Alansplodge (talk) 10:45, 13 August 2022 (UTC)

We used to go blueberry picking on Kit Hill when I was a boy. The blueberries we picked were urts, not the nasty American things most supermarkets sell as blueberries. DuncanHill (talk) 20:03, 15 August 2022 (UTC)

I knew the name Cloudberry from The Little Grey Men. The name seemed appropriate for a nature-associated character who flew with the geese; it never occurred to me that it might be a real fruit. -- Verbarson  ^talk_edits 10:55, 13 August 2022 (UTC)

I'm in Canada, and the one place I remember seeing the word "lingonberry" used was in an Ikea store: for example, this product. I'd guess that Ikea stores in Britain would also have such things. --174.95.81.219 (talk) 10:19, 14 August 2022 (UTC)

Ah yes, you can get lingonberry jam from Ikea here in the UK. Alansplodge (talk) 10:47, 14 August 2022 (UTC)

I live in the United States, and when I think lingonberry, I think Ikea. Cullen328 (talk) 18:57, 15 August 2022 (UTC)

Not something you'd find with your average cream tea. Alansplodge (talk) 12:07, 16 August 2022 (UTC)

I've had whortleberry cream tea in Somerset, and that first link is a disambiguation page that suggests it could mean either bilberry or lingonberry. AlmostReadytoFly (talk) 13:41, 16 August 2022 (UTC)

Cloudberries certainly do grow in Britain, well at least in Scotland (see here). Mikenorton (talk) 21:28, 15 August 2022 (UTC)

It is a true sub-Arctic species, more often found in Scandinavia than Scotland. Possibly because of this we rarely see its snowy flowers or ruddy orange fruit in our Scottish hills. Cloudberry - Friends of Loch Lomond & The Trossachs. Alansplodge (talk) 12:06, 16 August 2022 (UTC)

Why is Hawaii so lumpy?

Would even slight crustal anisotropies cause a positive feedback loop of crust weakening that ends with the magma only coming out in some places? I would've expected less deep gaps like the 16,000 to 20,000 foot deep one between Maui top and Big Island top (16,000 feet below Maui's top and half the average depth of the ocean). Kauai and Oahu also have a very wide "col" in between about 14,000 to 15,000 feet below the peaks, the saddle between the two Mauna volcanos that form much of the Big Island is much less deep and wide. Sagittarian Milky Way (talk) 22:54, 13 August 2022 (UTC)

From where do you get the expectation that it shouldn't be? --Jayron32 14:37, 15 August 2022 (UTC)

Continental drift is so slow I would expect a main island hundreds of miles long. Maybe the plate isn't anywhere near isotropic? The magma seems to only want to come out in a small amount of weak zones per island. Sagittarian Milky Way (talk) 17:19, 15 August 2022 (UTC)

It's not the absolute speed of plate tectonics, it is the relative speed of the movement of the plate in question (which is not constant) and the rate of lava flow (which is also not constant) of the hotspot under Hawaii. The lava forming the islands may stop flowing for millenia at a time, flow rapidly and continuously at other times, etc. etc. It's a complex process. --Jayron32 17:49, 15 August 2022 (UTC)

A simple volcano built up on oceanic crust causes lithospheric flexure due to the load caused by the volcanic build up itself, so that gives you one kind of topography - a central low surrounded by a less-marked marginal high. In reality many volcanoes are the result of the coalescence of more than one volcanic centre, each with there own individual topography. The load caused by the individual volcanic centres within a single island will not normally be expressed at the top of the oceanic crust, so you just get the shape of the volcanoes themselves, making them pretty lumpy. Oceanic crust is pretty homogeneous, although it sometimes contains old fracture zones, which remain zones of weakness that may affect later volcanic development - those near Hawaii are nearly west-east trending. The hotspot beneath Hawaii remains plumbed into the volcanoes even as they drift away, until the main location of active vulcanism jumps to form a new volcano (and island eventually), forming the chain that we see. Mikenorton (talk) 21:18, 15 August 2022 (UTC)

That makes sense. Maybe Molokai is an old fracture zone? Sagittarian Milky Way (talk) 21:32, 15 August 2022 (UTC)

Molokai sits close to a major fracture zone, in fact the "Molokai fracture zone", although I can't find any sources to support a direct link between the fracture zone and the island/volcano, although there is a marked change in crustal/lithospheric thickness across the Molokai F.Z. Mikenorton (talk) 12:52, 16 August 2022 (UTC)

August 14

Solar-powering a freezer: how much anti-freeze water to keep contents frozen overnight

I was thinking about energy storage and solar power and how maybe phase change inside a freezer could allow a freezer to operate soley on solar energy. I'm not entirely sure that it's worth the trouble in practice (I think it is since lithium batteries are expensive) but I was wondering whether anyone could verify my calculation. The first result on Google suggested a typical consumption for a freezer is 0.6 kWh per day and I presume solar power to be available 8 hours per day so the freezer would need to store 0.4 kWh in frozen water, neglecting heat pump efficiency. If 0.4 kWh = 1.44 MJ and 1.44 MJ / 6.02 kJ/mol = 239 mol then I calculate 4.3 litres of water are needed. If ethylene glycol is added to lower the freezing temperature of the water, does that also significantly affect the enthalpy of fusion of the water? The enthalpy of fusion of ethylene glycol is greater than that of water but I don't know how that's affected when they mix. 78.148.95.111 (talk) 12:28, 14 August 2022 (UTC)

0.6 kWh/day seems a bit poor to me, but it depends on the size of your freezer.

You neglect heat pump efficiency. With a coefficient of performance of 1, the electric energy used is equal to the heat removed from the freezer, for which your calculation is correct, but most freezers are better (around 4), so you may need a bit more ice. On the other hand, if you keep the door closed while it's switched off, you'll need less. The freezer specs may mention the time they typically remain frozen after a power failure. It seems that many can handle around 24 hours, provided you keep the door closed and the environment is not too hot.

Don't count on 8 hours of sunshine per day. In summer you may get more (here, it's often over 14 hours), but in winter, less (sometimes in November 8 hours for the entire month). Of course, in winter you may need less energy. Solar panels provide some electricity under an overcast sky, but it's negligible. Adding something to the water to lower the freezing point is a good idea, as it allows keeping the freezer well below freezing, which you probably want.

In the past, people kept their cold storage rooms cold the entire summer using blocks of ice. PiusImpavidus (talk) 20:00, 14 August 2022 (UTC)

Why not insulate your freezer properly, overcool it during the day, let it warm up to -18 deg C overnight? Greglocock (talk) 09:42, 15 August 2022 (UTC)

Is this a real-world application or are you just doing theoretical calculations? You brought up batteries; if cost is the driving factor, and the weight is not a big deal, lead-acid batteries win on cost-to-power ratio. This is why ICE vehicles use them, and why off-grid power applications generally do, until you get up to utility-scale stuff where other factors come into play. Lithium-ion batteries are used where capacity and low weight become the overwhelming factors, such as in portable electronics and a lot of battery electric vehicles, though many of the latter still go with NiMHs because they're cheaper with still competitive qualities, and also have fewer safety issues. Also, with the presence of solar energy, using the sun's heat may make an absorption refrigerator competitive. These are used in RVs because they can run directly from a heat source, such as fuel combustion. As with solar water heating this avoids the substantial losses you incur from the solar panel (commodity panels have only around 20% percent efficiency). --47.147.118.55 (talk) 08:00, 16 August 2022 (UTC)

August 15

Artificial improvement of acoustic transmission

Is it theoretically possible to maximally improve the acoustic transmission and lower the acoustic impedance within some enclosed space, e.g. by warming the air and pumping more air within safe pressure limits for human body, with the aim of better hearing quiet and distant sounds? Excluding existing examples of acoustically designed music venues and opera houses. 212.180.235.46 (talk) 10:19, 15 August 2022 (UTC)

There was an accident where oil rig divers were in a slow depressurization chamber (to prevent the bends) and at least 9-10 bar made their bodies sort of explode when both sides of an airlock were open simultaneously. Sagittarian Milky Way (talk) 13:08, 15 August 2022 (UTC)

Have you any more data on that? Normally the doors are designed such that they can only be opened where the pressure is equal, typically by only opening towards the high pressure side. Martin of Sheffield (talk) 13:11, 15 August 2022 (UTC)

Byford Dolphin. Actually it was 9 atmospheres above vacuum, only ~8.005 atmospheres above outside pressure. Sagittarian Milky Way (talk) 13:23, 15 August 2022 (UTC)

Thanks. It makes horrific reading, the only saving grace is that death must have been instantaneous and they would have known nothing about it. I do note though that the design was from 1975 and the Norwegians were already tightening up on it. Brrr. Martin of Sheffield (talk) 13:43, 15 August 2022 (UTC)

To truly maximize pressure and the speed of sound you'd need to fill it with pure pressurized hydrogen and breathe 0.something precent oxygen the rest hydrogen through a mask at similar pressure to get as close to the world record of c. 70.1 atmospheres as you dare which would cause health problems and make some instruments octaves higher (but not speakers playing a recording). It would also be uncomfortably hot which would pollute the hydrogen with a possibly small amount of dried sweat. I suppose you could paint a thin coat of something waterproof and airtight on the ear canal (not the eardrum) and wear a backless waterproof airtight suit with a seal at each ear opening and instead of a back a silhouette-sized tunnel connected to the most silent cooling system possible providing air conditioning from out of earshot. And wear old-fashioned gramophone-looking ear cones if that's not cheating. Sagittarian Milky Way (talk) 21:15, 15 August 2022 (UTC)

One issue with any optimization you're suggesting in a real-human-world environment (like a concert) is that I think anisotropies in the air and noise propagation will cause far more signal loss than any gains reducing impedance might bring. Obviously your sound is great in the ocean (once you filter out the insane amount of noise), but that's an enormous change in impedance, and I'm not sure, but it might be that you'd expect the local anisotropy (that is, over a fixed volume) of something like air on Earth at sea level in good conditions to be greater (in manners that would most affect acoustic signal) than that of water or the ocean in some other reasonable real-world circumstance (and the reason I think this is reasonable is that water will generally have uniform density throughout these volumes whereas air in these conditions need not). SamuelRiv (talk) 23:54, 15 August 2022 (UTC)

Fun almost irrelevant fact. Tires have a ring mode in which a resonant wave forms around the circumference.It can be a bit hard to identify it (to the cloth eared, it is clear as a bell to me), so we fill the tire with CO2 and see which resonances move in frequency. Greglocock (talk) 00:00, 16 August 2022 (UTC)

Besides the telegraph key...

... (or maybe it isn't even functioning here as a telegraph key), can anyone explain what else is going on with this board, recently seen in an antique shop in Oregon? - Jmabel | Talk 18:47, 15 August 2022 (UTC)

Some sort of Wheatstone bridge perhaps. catslash (talk) 20:51, 15 August 2022 (UTC)

A similar one from a New Mexico University Physics lab was sold on Ebay: https://www.worthpoint.com/worthopedia/chicago-apparatus-company-wheatstone-1855290011 Modocc (talk) 21:03, 15 August 2022 (UTC)

Very similar indeed - and it confirms that there should be metal pegs.catslash (talk) 21:12, 15 August 2022 (UTC)

Also that the banana connector-cum-binding post terminals are not original.catslash (talk) 21:37, 15 August 2022 (UTC)

It's clear that the wound impedances are designed to be shunted by the insertion of metal pegs - so that in the absence of the pegs, both upper branches are each set to 111ᾨ.

Probably the screw terminals form a pair, likewise the terminals labelled x-x, the two top-centre terminals and the two bottom right terminals. catslash (talk) 21:05, 15 August 2022 (UTC)

It's a demonstration Wheatstone Bridge, new form. Catalogue number 1073E "Easier for the student to understand". Cost $13.50 new. DuncanHill (talk) 21:26, 15 August 2022 (UTC)

August 16

Light travel delay and observation of astronomical objects

If I understand correctly, when the light from a distant space object reaches the observer the observed object moves elsewhere, effectively making the observed object a sort of a ghost-like hologram. Because of that does the time delay of travelling light require position and time adjustments of observed objects (such as stars, including our Sun)? Does it affect position-sensitive measurements, such as parallax? 212.180.235.46 (talk) 11:19, 16 August 2022 (UTC)

The stars that move the most relative to the observe background each year (have the largest proper motion) are also the stars that are very close and have some of the highest stellar parallaxes. Even though their observed tangential velocity is still (just) less than 1% of the speed of light, the transverse Doppler effect ([StackX overview) should still be measurable, but I'm not sure how astronomers do that (and I'd think measuring that would give useful information on radial velocity, but I could easily be wrong, not working the math). More to the point, the special relativistic effects similar to what you describe are definitely an important factor in eclipsing binaries, most famously in Ole Romer's first measurement of the speed of light by the moons of Jupiter. SamuelRiv (talk) 12:58, 16 August 2022 (UTC)

• (edit conflict) We have an article about aberration (astronomy), but it’s really verbose / dry. Tigraan^{Click here for my talk page ("private" contact)} 13:01, 16 August 2022 (UTC)

Yes, having established what we as observers think of as an inertial frame that we use to assign positions to objects, if we see an object at time t₀ at position p, and we know that the time it takes for the light to reach us equals Δt, we have observed that the object was at position p at time t₀ − Δt. If it is moving steadily and we know its velocity, we can extrapolate to obtain an estimate of its current position (in our frame). I don't think this is generally considered to be a relativistic effect.  --Lambiam 15:41, 16 August 2022 (UTC)

Sky atlases show the sky as it was. When the dot says Barnard's Star is here at 1900 and over 5/9ths of a degree towards this direction in 2100 and here in 1950 and 2000 and 2050 it doesn't account for the fact that it's really over 8 years ahead. Sagittarian Milky Way (talk) 05:40, 17 August 2022 (UTC)

Electron charge and speed

Does the charge of an electron decrease when it waits for a relativistic speed? For example as its mass was shown to increase. — Preceding unsigned comment added by Malypaet (talk • contribs) 14:18, 16 August 2022 (UTC)

I'm not sure what you mean for "waits for a relativistic speed"? Charge remains constant at all velocities in all frames of reference, though properties such as "charge density" and "specific charge" (which depend on volume and mass respectively) will change, because distances and masses are dependent on relative velocities. Be very careful on what you are measuring here. "Charge" is not the same as "specific charge" is not the same as "charge density". --Jayron32 14:33, 16 August 2022 (UTC)

sorry, reaches, not "waits".

How can you say that charge remains constant at all velocities in all frames of reference ?

What metric are you basing it on ? Malypaet (talk) 21:39, 16 August 2022 (UTC)

French attendre means "to wait", while atteindre means "to reach". A one-letter difference.  --Lambiam 07:41, 17 August 2022 (UTC)

You're getting into a very good question, which is essentially noting that gravitation and electromagnetism behave pretty darn similarly (true), but the concept of "charge" in gravitation (mass) and that in electromagnetism (electric charge) are very different in many respects, not least of which is that electric charge is Lorentz-invariant (which is experimentally verified, which is more or less how we know it's not not-true) (and rest mass is of course invariant). If you know your physics there's a really good explanation on StackX that sort of gets at how you could formulate a Lorentz-invariant mass-gravitation theory (I'm pretty sure this is gravitomagnetism, which is not nearly as useful as GR but can get around some nasty problems). I don't know that there's a useful non-Lorentz-invariant theory of electromagnetism, however (You might need to crank the exoticness of your particle theory up a notch for that). SamuelRiv (talk) 23:00, 16 August 2022 (UTC)

I wish people would finally drop that useless and harmful idea that mass should depend on centre-of-mass velocity. It doesn't explain anything and it leads to so many misunderstandings. Just let mass be rest mass, an intrinsic property of a body that is independent of reference frame. --Wrongfilter (talk) 08:37, 17 August 2022 (UTC)

Yes, but separating "rest mass" from "relativistic mass" doesn't take into account that an object's inertia is affected by its velocity. This feedback is much more mathematically convenient if you treat it as a mass. I'm sure there's other ways to slice that mathematical pie, but they are less efficient than treating the changes to inertia as a change to mass. --Jayron32 10:43, 17 August 2022 (UTC)

An object's inertia is not affected by its velocity. What does that even mean? There is no such thing as absolute velocity that could influence inertia. Relativity is a theory of space-time, and it describes how different observers see the object. Which of the many possible observers do you think determines the inertia of the object? --Wrongfilter (talk) 11:09, 17 August 2022 (UTC)

So, what you are saying is that the work needed to accelerate an object moving from 98% the speed of light to 99% the speed of light is the same as the work needed to accelerate the object moving from 1% the speed of light 2% the speed of light? Interesting. Please tell me more. --Jayron32 11:52, 17 August 2022 (UTC)

98% of the speed of light with respect to what? The difficulty of accelerating with respect to some reference frame is due to relativistic velocity addition (space-time!) not to some change in the properties of the object. I know people like this mechanistic argument and they imagine they understand something, but it really goes against what relativity is all about. --Wrongfilter (talk) 12:10, 17 August 2022 (UTC)

The point is that, while you can do formulations both with and without relativistic mass as a concept, that doesn't mean that relativistic mass is not a useful concept. When you put it in the formulations that use it, and turn the crank, you get the same right answers as when you reformulate those equations to avoid using it. There's an unfounded prejudice among some people that because things can be re-written to avoid using it, that it isn't a "thing". It's a fine concept. It works. Physics doesn't need to eliminate it. It doesn't need to have it either, but that is not a reason to pretend like it's an abomination. If you can use it and always get the correct predictions, have at it. --Jayron32 15:06, 17 August 2022 (UTC)

You could have fooled me. Some people think that relativity is just a theory that has little or no practical application. But this is not so. In the design of cathode ray tubes (until recent years used as the display device in TV receivers and lab instruments), the relativistic mass and consequent inertia has to be taken into account. In typical CRT's, a high voltage (circa 15 to 30 KV) is used to accelerate electrons in a very narrow beam to hit a phosphor screen with enough energy to cause light emission. Electromagnets or electrically charged plates were used to deflect the beam left and right and up and down. The amount of current or voltage, respectively, to deflect the beam any given angle is always slightly greater than electron rest mass would indicate. This is because the electrons travel at an appreciable fraction of the speed of light and so the electron inertia is increased a little. Dionne Court (talk) 12:11, 17 August 2022 (UTC)

The phenomenon can be explained by Lorentz transformations (space-time) on the four-momentum (energy + three-momentum) without invoking mass increase. --Wrongfilter (talk) 12:15, 17 August 2022 (UTC)

As Jayron said, it is mathematically convenient to calculate on the basis of a mass increase. And it works - you get what you can measure.

Jayron asked is the energy needed to go from 0.98c t0 0.99c the same as for 0.01c to 0.02c. And your answer is? A simple direct answer now, is it the same or is it different? If it is only different under certain circumstances, what are those circumstances? Dionne Court (talk) 14:44, 17 August 2022 (UTC)

Of course it's harder for a spaceship to go from 0.98c to 0.99c relative to Earth. The question is why is that? Your answer is that the rocket is getting more massive. Put yourself on the spaceship and your answer will be Earth is getting more massive. I'm sitting on Earth and I dispute that it is getting more massive just because something somewhere is moving fast relative to Earth. Of course you can define $\gamma m_{0}$ to be some quantity $m$ and you'll get the same answer. That is not my point. My point is about the interpretation of the theory as a theory of the geometry of spacetime. I could dig out John Archibald Wheeler's take on "relativistic mass" and the importance of invariant quantities (which rest mass is and mass ought to be) but I'm tired... --Wrongfilter (talk) 15:29, 17 August 2022 (UTC)

Of course invariant quantities are important, to bring this back to the original question, which is why I reminded the OP about the difference between charge (an invariant quantity that everyone will measure the same in all reference frames) and charge density or specific charge, which people in different reference frames would measure differently. Take specific charge for example: the differences between specific charge as measured in different reference frames can be calculated using differences in mass (i.e. relativistic mass) or by doing some complex bit of mathematics using Lorentz transformations and the like. They both give the same right answer; and some people prefer the more efficient explanation using relativistic mass. Merely because relativistic mass is not an invariant doesn't make it useless or verboten. Understanding invariants is useful for deep theoretical foundations, but it isn't required to build sound models that produce accurate results that match reality. --Jayron32 16:03, 17 August 2022 (UTC)

I didn't get an answer to my question

A constant velocity ion with two electrons missing, caught by an electron it captures:

- Its charge decreases

- Its mass increases

- Its speed increases

So what experiment shows that the electric charge of an electron is independent of its speed ? Malypaet (talk) 21:18, 17 August 2022 (UTC)

Of course early 20th century scientists discovered the electron, its properties and charge conservation. More specifically, the constancy of charge with respect to its speed is empirically supported by and consistent with hundreds of thousands particle accelerator experiments, List of accelerators in particle physics. --Modocc (talk) 22:59, 17 August 2022 (UTC)

I can find many papers giving the charge/mass ratio of an electron according to its velocity and deducing the mass based on the assertion of the constancy of charge, but no experiments measuring charge alone.

Apparently no one is able to name a single one here too!

And as for load constancy, in my example, it doesn't apply at the macro level. Malypaet (talk) 08:50, 18 August 2022 (UTC)

Of note, the electrons' energies do change w/ accelerations because their significant kinetic energies are delivered to various targets that are struck within the atom smashers with predictable results, yielding the well-known and established relativistic relationship between their kinetic energies and their speeds (without involving their electric charge). Given mass-energy equivalence, charge conservation is therefore verified empirically by measuring an electron's mass-to-charge ratio since its speed is measured such that its energy and mass can be calculated. Modocc (talk) 13:21, 18 August 2022 (UTC)

Sources?

Experiment with publication peer reviewed ? Malypaet (talk) 22:13, 18 August 2022 (UTC)

I'm not really visualizing the capture process you're describing in this experiment, but I don't think it matters. The measurement process for the charge of an individual ion (say deflection in a magnetic field) would show the same result regardless of velocity relative to the observer: so if you took an ion through a cloud chamber in a magnetic field (clouds, the observer (you), the field generator, are all fixed) the ion would behave as predicted by the Lorentz force with constant charge regardless of the speed you throw it at, and that's confirmed by experiment. That's actually how they did all this back in the day, and there's another thing that binds experiment and modern theory (and even special relativity) into a nice bundle (if you accept one of the things as true, at least, then the rest are self-evident): CPT symmetry (Gentle introduction from Nave if you start at the beginning of the lecture). Fair warning: if you were worried about the sanctity of charge, I'd suggest not asking angular momentum where it's been all weekend. SamuelRiv (talk) 03:32, 18 August 2022 (UTC)

There are all the same many experiments which give a mass and a charge to the photon, except the acceleration of an electron is only done by the addition of electromagnetic energy, therefore of photons.

Could this be an explanation for the increase in the mass/charge ratio of an accelerated electron, as in my example with the ION? Malypaet (talk) 09:00, 18 August 2022 (UTC)

For visualizing, imagine an elementary liquid battery ! Malypaet (talk) 09:02, 18 August 2022 (UTC)

This thread on Stack Exchange may be useful here, it asks (and answers) what I think is roughly the same question you have about proving charge invariance. --Jayron32 13:18, 18 August 2022 (UTC)

No, this thread didn't give experiment with peer reviewed publication. Just assertions. Malypaet (talk) 22:17, 18 August 2022 (UTC)

August 17

Red-green colorblind.

Which green is for red-green colorblind? I have a feeling it is the light model, rather than the paint model. So "dark green" is more differentiated from the red. 67.165.185.178 (talk) 09:27, 17 August 2022 (UTC). Edit: and someone feel free to shrink the images. 67.165.185.178 (talk) 09:28, 17 August 2022 (UTC).

I shrunk your images. --Jayron32 10:48, 17 August 2022 (UTC)

It's not a specific shade, rather its a range of color families that get confused. See Color blindness for more information. The human eye has three different kind of colored light receptor cells known as cone cells, and each is sensitive to a different range of colors, roughly corresponding to wavelengths of light around the red, green, and blue ranges respectively. In people with red-green colorblindness, their "red" and "green" receptors essentially respond to the same wavelengths of light in the same way, so the entire range of colors that could be distinguished differently by those two receptors all look the same to them. --Jayron32 10:52, 17 August 2022 (UTC)

I always thought it was by wavelength of light, and so, 555 nm of green for example. So I wonder what does pink look to a red-green colorblind person. 67.165.185.178 (talk) 12:07, 17 August 2022 (UTC).

555 nm is perceived as a shade of green, but there are other ways you can perceive green, for example as a mixture of other wavelengths, none of which is in the range of 555 nm, but which stimulate your three cone cells in such a way that your brain can't tell the difference, you will still perceive that as green. Color vision is much more complex than you seem to be thinking of it. The answer is that people who are red-green color blind perceive colors like, say pink and sea-green to be indistinguishable from each other. --Jayron32 12:53, 17 August 2022 (UTC)

The color blindness article talks about inability to tell a red apple from a green one, and has a section on red-green color blindness, but that section only describes the inability to tell the neutral point (between the two cones) from white: it does not describe a mechanism for inability to tell spectral red from spectral green, and logically two different types of cone cell (blue and red, anyway) should suffice to distinguish all spectral colors. I don't get it.  Card Zero  (talk) 16:06, 17 August 2022 (UTC)

The point is, you don't see spectral colors either. You see stimulations of the cone cells in the retina of your eyes, and each cone cell responds to both intensity and wavelength of the incoming light, and your brain does a complex bit of processing to determine what color you perceive. Even with normal color vision, you cannot distinguish between a pure wavelength of light that you interpret as a specific color (say, for argument's sake, "yellow" at 580 nm) and a mixture of wavelengths that with absolutely no contribution at all from 580 nm light, but which stimulates the three kinds of cones in the same way that 580 nm light does. You just see "yellow" in both cases. That's why the RGB color model works in things like TV displays. A series of closely spaced dots of only three very specific wavelengths is enough to make you see all of the other colors as well. The display on your phone, TV, computer monitor, produces essentially no light of wavelength 580 nm and yet, you can see yellow on that display just fine. Because all you see is the stimulation of your cone cells, as processed by your brain. The way to think of color blindness in this way is that the brain of colorblind people is still expecting inputs from three different kinds of cone cells, but two of them are sending the same signals. So, anything that in a non-colorblind person would stimulate the red cone cells differently than it would the green cone cells, in a colorblind person would be stimulating both kinds of cone cells the same amount, all the time, regardless of what the incoming light is. As a result, their brains interpret as the same color two colors that a non-colorblind person would interpret as different. It doesn't really matter what is happening at the blue cone, the brain expects three signals and is still processing the input like three signals coming in. So it interprets every possible combination of inputs on the red and green cones as some shade of yellow, which is what "equal amounts of red and green stimulation" tends to mean in a non-colorblind person. And that isn't strictly correct; since color is a qualia, there's real problems with associating the color one person sees, in an absolute sense, with what another person sees. But you get the idea. --Jayron32 16:25, 17 August 2022 (UTC)

Singular: quale.  --Lambiam 17:35, 17 August 2022 (UTC)

Some parameters:

• This question-hijack is only about spectral colors.
• Let's suppose the person's short and long wavelength cones work, but the green ones aren't sending a signal.

So spectral red should stimulate the red cones a lot, and not the other type(s), which is just what red ordinarily does. Then spectral green should stimulate the red cones somewhat and the blue cones somewhat less, and yet not stimulate the green cones at all (since they're missing), which I guess is an impossible color, but why would it register the same as red? Now I'd better read that article too. Maybe later.  Card Zero  (talk) 16:38, 17 August 2022 (UTC)

It's not that the green ones don't exist, or don't send a signal (at least in normal red-green color-blindness, perhaps there is some disorder where that happens; I've not heard of it), it's that the green ones and the red ones exist and send signals perfectly fine, and they are differentiated by your brain, but the two respond to light in the same way. I'm not really sure what would happen in your situation, because it's not a thing as far as I am aware. (also, I've greatly simplified the process of red-green colorblindness, aka Daltonism, it's a bit more complex, but this gets the spirit of it). --Jayron32 17:35, 17 August 2022 (UTC)

Must be.

I was following the article, where it says Deutan (6% of males): Lacking, or possessing anomalous M-opsins for medium-wavelength sensitive cone cells. I figured "lacking" would be the simplest case. But if the green-sensitive cells are responding to red, then spectral green should still look unlike spectral red, because it would stimulate the blue cells a bit. Or ... maybe the responses are narrow enough that relative closeness to blue is imperceptible. That must be it.  Card Zero  (talk) 17:57, 17 August 2022 (UTC)

You could very well be right then... I'm getting in over my head, and am backing out in favor of your clearly greater expertise here. --Jayron32 18:06, 17 August 2022 (UTC)

Just trying to make reality conform to the explanations I've somehow got hold of. Or the other way round. I don't know about expertise, we're all just making finger-puppets in a cave, or whatever Plato said.  Card Zero  (talk) 18:20, 17 August 2022 (UTC)

(edit conflict) If we go all math-y, each cell cone type detects the integral of the object’s radiation over all wavelengths weighted by the cone spectral sensitivity.

It is therefore true that two different types of cone cell [suffice] to distinguish all spectral colors (as long as the ratio of spectral sensitivities of the two cones varies along the whole spectrum, and subject to signal-to-noise limitations at very low sensitivities). [EDIT: the signal-to-noise stuff is likely the cause of most difficulties, see below.] But it does not prevent a "red" apple (which is not monochromatic-red) to have the same few weighted integrals as a "green" apple. In fact, it is fairly clear that as the eye sees in a few discrete colors (two or three), most of the information of a continuous spectrum is lost, and therefore many objects with random continuous spectra will appear the same to the discrete-transform of the eyes. (Of course, that’s with the math hat on; with the biology hat on, "random continuous spectra" do not occur in nature, and a small number of well-chosen discrete colors probably gives 99.9+% of the environmental information needed to thrive in most ecosystems, and avoids the need to synthetize hundreds of different photosensitive receptors.)

I find it hard to believe that someone who can link to spectral colors missed this; sorry if I misunderstood the source of your confusion. Tigraan^{Click here for my talk page ("private" contact)} 16:32, 17 August 2022 (UTC)

Oh, good! Non-spectral apples, that did cross my mind, but the main thing is, spectral red and green would look different? So fully-saturated red and green on a computer screen would in fact be distinct to a red-green color-blind person. Which sounds intuitively like the purest example of what they should not be able to distinguish, so the counter-intuitive reality is interesting.  Card Zero  (talk) 16:45, 17 August 2022 (UTC)

I don't believe so. LED traffic signals output essentially monochromatic light, and the red and green can be confused by someone with red-green colorblindness. This discussion thread between people with colorblindness note tricks they use, from location of the bulbs, to senses of brightness or saturation to tell them apart, but they are not able to distinguish them by hue. --Jayron32 17:44, 17 August 2022 (UTC)

Hmm, I do have to amend my answer above somewhat - it does not contain anything wrong but it’s certainly misleading and too math-centric.

Let us assume deuteranomaly, the most common form of color blindness, where the individual lacks functional M-cones ("green" receptors). If you look at the graph of cone sensitivity vs. wavelength posted above, you can see that above ~550nm, the S-cones ("blue" receptors) have essentially zero sensitivity. (Perception of light is highly non-linear etc. etc. so I am not sure what the actual threshold is, but the point is that L-cones see nothing beyond a certain threshold.) Therefore, in that area, a deuteranomalous person "sees" a single color channel (from cones at least). And then, the L-cone response is non-monotonous, so two points of the curve that have the same height are perceived as the same color; eyeballing the curve, this happens at 550nm (clear green) vs. 590nm (orange-ish red).

So while mathematically, two colors channels are enough to distinguish any two spectral colors, physically, the S-channel does not work in a large range (because of perception threshold / signal-to-noise / etc. issues), thus deuteranomalous humans can only rely on one channel in that range, which causes them to mix up certain colors. However, there is no real reason that "pure" colors should be harder to distinguish than "mixed" colors (without making assumptions of the spectrum of the "mixed" colors). Tigraan^{Click here for my talk page ("private" contact)} 08:57, 18 August 2022 (UTC)

Does the sea need rain?

Cloud-seeding made me think of this. Suppose there was some technological means (with no side-effects, for the purpose of this question) by which people diverted all rain to fall on land. Would this be ecologically harmful to the sea somehow? I suppose there'd be more stuff washed into the sea, leading to algae blooms and maybe salinity increase. Can't think of any other drawbacks.  Card Zero  (talk) 17:30, 17 August 2022 (UTC)

I'll leave it to those versed in geography, hydrography, climatology, etc. to answer this in depth, but in the most naive estimation (using simple available numbers) we can take the 1.386 billion km^3 of total water (I believe this includes vapor) on Earth, 1.338 billion km^3 (96.5%) being in oceans; and the 505,000 km^3 of annual water falling as precipitation, 398,000 km^3 (about 80%) over the oceans; and calculate that that if none of the rain that fell on land returned to the oceans in a balancing cycle, the oceans would be depleted in at least 13,000 years (much longer, maybe 2x-10x longer or so, because it's actually a differential equation even in a simple estimation as the rate of evaporation from the oceans and thus their contribution to rainfall decreases as they are depleted, as does the total area over which rain will conceivably fall into it, again being completely naive with this calculation), which to me sounds extremely fast, but the water cycle is enormous. The average annual drop in sea level is surprisingly tricky to measure (and varies by region) based on water volume alone, but there's probably a simple estimation method somewhere. SamuelRiv (talk) 17:58, 17 August 2022 (UTC)

I wasn't expecting the water to pile up on land and stay there! Though this literal interpretation is pleasing.  Card Zero  (talk) 18:05, 17 August 2022 (UTC)

Ohhhhhh! So this isn't the "I demonstrate basic arithmetic using a grade-school understanding of Earth science" Reference Desk! SamuelRiv (talk) 18:09, 17 August 2022 (UTC)

Rain water does not contain mineral salts, unlike the river water that flows into the seas. The influx of mineral salts would about triple. Since sea water is already so much more saltier than river water, by a factor of about 300, while the yearly influx of river water is less than 1/2500th part of the ocean water volume, I guess it will take centuries before the effect in increased salinity exceeds 1‰.  --Lambiam 18:19, 17 August 2022 (UTC)

But while the flow of river water increases, the concentration of dissolved materials in this river water could decrease. The concentration of suspended solids obviously increases after heavy rain, but I expect the total amount of nitrates coming from farmland to remain the same. That's set by what the pigs and chickens drop. PiusImpavidus (talk) 10:47, 18 August 2022 (UTC)

• "High levels of rainfall are commonly observed over the tropical regions of Earth's oceans, impacting physical processes that influence weather and climate from the microscale to the basin scale."
• "Rain alters the physics and carbon chemistry at the ocean surface to increase the amount of CO2 taken up by the ocean."
• "...rain and wind effects combine nonlinearly to enhance air-water gas exchange. "
• "Rainfall over the sea modifies the molecular boundary layers of the upper ocean through a variety of different effects. These cover the freshwater flux stabilizing the near-surface layer, additional heat flux established due to rain versus surface temperature differences, modification of physical parameters by temperature and salinity changes, enhancement of the surface roughness, damping of short gravity waves, surface mixing by rain, and transfer of additional momentum from air to sea."

References

The above (thanks User:Fiveby) is the kind of thing I had a hunch must be the case: that the life in the ocean needs regular watering for some reason. Putting CO2 into the water makes it more acidic and is generally thought of as a bad thing, but presumably the splashing rain also helps oxygenate the water, which must matter a lot for life near the surface. The last link hints at a layer of reduced salinity and moderate temperature as well, but I don't know if that constitutes an environment that maybe plankton depends on. I'll also just note that "gravity waves" are not the same as gravitational waves, because that took me a moment.  Card Zero  (talk) 13:50, 18 August 2022 (UTC)

IIRC, there are some animals that returned to the sea, but still prefer to drink fresh water, like sea snakes. After heavy rain, the fresh rainwater doesn't mix immediately with the denser seawater, so they can drink relatively fresh water from the top few millimetres. PiusImpavidus (talk) 10:47, 18 August 2022 (UTC)

August 18

Climate

Moved from Wikipedia:Teahouse § Klima

Ist die aktuelle Klimaveränderung natürlichen Ursprungs oder / und Folge der Industrialusierung. 2.247.248.83 (talk) 03:00, 18 August 2022 (UTC)

Bitte versuchen Sie es mit dem Referenzschalter.

Original post translated through Google Translate: Climate / Is the current climate change of natural origin or / and the result of industrialization. 🐶 EpicPupper ^{(he/him | talk)} 03:05, 18 August 2022 (UTC)

The answer is "Yes". ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:45, 18 August 2022 (UTC)

The climate has a "natural" change component responsible for ice ages and interglacials, which is discussed in the article Milankovitch cycles. Overlaid on that process there can now be little doubt there is also a human-induced climate change. So the answer is "und nich oder". Were it not for global warming on a 50-year timescale which rightly worries most people, we might be worrying about global cooling on a couple-of-century timescale: i.e. when we might expect the current interglacial to end. Mike Turnbull (talk) 14:20, 18 August 2022 (UTC)

Disproportionate toxicity of small animals

Why did some small animals, such as Irukandji jellyfish, evolved disproportionately potent toxins relative to the size of their prey which can also kill much larger animals, such as humans? One may think that from an evolutionary standpoint, evolving such excessively toxic substances would be costly and their evolution would stop at a point sufficient to kill typically sized prey, yet they exist. Why is that? 212.180.235.46 (talk) 13:05, 18 August 2022 (UTC)

"Researchers conjecture that the venom possesses such potency to enable it to quickly stun its prey, which consists of small and fast fish". In other words, just one or two stingers will quickly stop the fish. I doubt that humans enter into it's evolution! Martin of Sheffield (talk) 13:12, 18 August 2022 (UTC)

One thing to consider; such toxins are also deadly to predators as well... Many of which may be considerably larger. --Jayron32 13:15, 18 August 2022 (UTC)

I did consider that, but the article doesn't mention predation so I didn't mention it. Maybe not deadly for something the size of a baleen whale, but unpleasant enough to diswade feeding perhaps? Martin of Sheffield (talk) 14:05, 18 August 2022 (UTC)

Animals that are toxic to dissuade predators usually advertise so with bright colours (some frogs, salamanders, fish, insects). This jellyfish is almost invisible; there's no way a filter-feeding baleen whale would see it before crushing it in its mouth. Large non-filterfeeding hunters wouldn't target such a small prey, so the toxins only help against predators up to maybe 5 kg. PiusImpavidus (talk) 09:11, 19 August 2022 (UTC)

Lina Medina

Is very easy to find photo and images of Lina Medina, but it seems there is not video footage existent. Have you noticed that? It is possible to find? 62.18.1.163 (talk) 14:10, 18 August 2022 (UTC)

Lina Medina is not a public figure, and as such, it is not surprising that there does not exist any video footage. Prior to the widespread adoption of smartphones since the turn of the 21st century, most people lived their entire lives without being filmed. --Jayron32 14:18, 18 August 2022 (UTC)

The article says films were made. Abductive (reasoning) 02:48, 19 August 2022 (UTC)

Also that some of them were lost, and the remainder never published. They are medical records of a 5-y-o child, presumably naked, illustrating aspects of her pregnancy, and the person is still alive – medical confidentiality obviously applies to them. {The poster formerly known as 87.81.230.195} 90.209.121.96 (talk) 04:04, 19 August 2022 (UTC)

Well, if Wikipedia somehow gets its hands on the pictures / films, it is not bound by rules that apply to medical professionals. But we still have Wikipedia:Image_use_policy#Moral_issues that would clearly forbid the use of such stuff. Tigraan^{Click here for my talk page ("private" contact)} 09:11, 19 August 2022 (UTC)

Bird ears

The ossicles are use by mammalian animals to pick up very low noises. Birds seem to have good hearing. They use sound to communicate a lot. How do they listen well without ossicles? -- Toytoy (talk) 09:20, 19 August 2022 (UTC)