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April 28

Vertigo

Is acrophobia amenable to treatment by exposure therapy, or does it require more invasive treatment (like anti-anxiety drugs, intensive psychotherapy, etc.), or maybe it's not amenable to treatment at all? (Not medical advice -- I suffer from mottaphobia (or, more precisely, papiliophobia or even more precisely, papilioglaucophobia), not acrophobia, and in any case this question was inspired by the film Vertigo.) 2601:646:9882:46E0:C6F:1E80:4BE5:575F (talk) 08:39, 28 April 2023 (UTC)[reply]

Vestibular rehabilitation therapy (VRT) is one such treatment.^[1] --136.56.52.157 (talk) 08:58, 28 April 2023 (UTC)[reply]

That is a therapy for vertigo, a condition in which the world seems to spin, also for patients at ground level. This condition is unrelated to acrophobia, "fear of heights". --Lambiam 17:47, 28 April 2023 (UTC)[reply]

The OP seems confused about this. They asked about acrophobia, but the header is Vertigo. -- Jack of Oz ^{[pleasantries]} 20:43, 28 April 2023 (UTC)[reply]

Right, because that's the name of the movie which inspired the question -- so it wasn't me who was confused, it was Hitchcock! 73.162.86.152 (talk) 02:44, 29 April 2023 (UTC)[reply]

This is the first time that that movie has been referred to in this thread. -- Jack of Oz ^{[pleasantries]} 22:01, 30 April 2023 (UTC)[reply]

Not so -- I referred to it in my original post, how come you didn't notice? 73.162.86.152 (talk) 21:56, 1 May 2023 (UTC)[reply]

Because I'm old. Some faculties fade, others are enhanced. You'll find out. -- Jack of Oz ^{[pleasantries]} 08:28, 2 May 2023 (UTC)[reply]

Look on the bright side: You're too old to die young. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:36, 2 May 2023 (UTC)[reply]

I shall try and remember that as my back aches and my joints creak! ;-) Martin of Sheffield (talk) 09:44, 2 May 2023 (UTC) [reply]

In Latin, vertigo is a non-medical term for "giddiness", such as may be experienced when gazing down from a great height or after imbibing a great deal of wine (or both). In English the term occurs as a non-medical term borrowed from Latin in the general sense of "giddiness"^[2][3][4] as well as the medical term for a specific condition, usually caused by a problem in the vestibular system. --Lambiam 11:36, 29 April 2023 (UTC)[reply]

This article from a reliable source gives a good account of vertigo and some of its causes/treatments. Mike Turnbull (talk) 17:32, 2 May 2023 (UTC)[reply]

A meta-analysis of the efficacy of different interventions for acrophobia, including "VR coach-delivered psychotherapy", "in vivo exposure augmented with oppositional action" and "VR exposure therapy with 20 mg cortisol administration", found that these were "significantly superior than the placebo/control interventions", with "VR coach-delivered psychotherapy" (a term not further defined or explained in the article) being ranked as the most effective intervention for acrophobia.^[5] However, in the concluding section, the authors warn that the overall evidence was not sufficiently strong for this conclusion. So, apparently, exposure therapy for treating acrophobia is given in different forms that are at least somewhat effective. --Lambiam 12:41, 30 April 2023 (UTC)[reply]

Thanks! So, there are some promising treatments, but these are somewhat more involved than ordinary exposure therapy (such as me looking at pictures of tiger swallowtails to get over my own phobia of them, which has been somewhat effective so far, at least in the case of the smaller Papilio rutulus), and they're not quite sure just how effective these treatments are yet -- right? 73.162.86.152 (talk) 21:56, 1 May 2023 (UTC)[reply]

Unusual bird call

I’ve recently heard a bird call I’ve never heard before, I was hoping someone may recognise it by description as I’ve not been able to get it on recording. It’s a short, sub-1 second, guttural deep warbling type call that essentially sounds like someone gargling mouthwash. It’s coming from a copse of mixed deciduous trees near my home. I live in the south west of the UK on a tidal estuary. The only bird I’ve visually identified in the copse is a group of jackdaws but not seen it to be them that make the noise. Googling it just brings me male brown cowbird but on YouTube comparison the cowbird is far too high pitched and too quiet, and I think are only found in the USA. This call is really loud. Thoughts? 2A02:C7F:2C68:D500:B5B4:AFF3:7763:AD63 (talk) 09:33, 28 April 2023 (UTC)[reply]

Jackdaws and rooks often roost together, and your description does sound vaguely corvid. Try an online birdsong identifier such as https://www.british-birdsongs.uk/ - if you're in the South West UK it could also be a carrion crow or a raven. Turner Street (talk) 09:46, 28 April 2023 (UTC)[reply]

Could it be a toad? Andy Mabbett (Pigsonthewing); Talk to Andy; Andy's edits 16:30, 28 April 2023 (UTC)[reply]

A fair question! But if it is it’s a toad that can throw its voice to the top of a cedar tree! I’ll YouTube some Corvid calls and see what comes up. 2A02:C7F:2C68:D500:5F:1DB4:4B22:FD1E (talk) 19:05, 28 April 2023 (UTC)[reply]

Heard it again this evening. It’s like someone talking underwater, or for a more niche reference it sounds like Richard Nixon shaking his jowls in Futurama… — Preceding unsigned comment added by 2A02:C7F:2C68:D500:30A4:1EAB:F159:428E (talk) 20:07, 28 April 2023 (UTC)[reply]

I managed to get a clip of it. You’ll have to turn the volume up a bit. Ignore the chirp at the very end, that’s something else and it was too close to the call I’m trying to ID to cut out. It’s the lower pitched, more guttural call I’m trying to identify. Here is the video 2A02:C7F:2C68:D500:5D4D:A32D:F2BF:F282 (talk) 06:56, 29 April 2023 (UTC)[reply]

MYSTERY SOLVED!! It’s a Little Egret. We finally spotted them. Never seen them in trees before. 2A02:C7F:2C68:D500:296A:F26B:CEF5:2400 (talk) 19:40, 30 April 2023 (UTC)[reply]

Little Egret ~ Bird Call ~ Bird Song on YouTube. --Lambiam 19:00, 2 May 2023 (UTC)[reply]

Harmless smoke

From what I've read it appears that every smoke and vapour (except possibly water vapour) is harmful to humans, regardless of its source (including herbal cigarettes). Is there a known substance whose burning would produce a harmless smoke/vapour in terms of inhalation? Or does burning in itself always inherently produce a toxic smoke, regardless of source? 212.180.235.46 (talk) 17:46, 28 April 2023 (UTC)[reply]

Any smoke has a complex composition because the high temperature facilitates chemical reactions that result in a large number of chemical compounds. Many of them will be toxic. So, yes any smoke is highly likely harmful. As to vapour: this term can be used for the gaseous phase of any chemical. So, a vapour many be harmless: oxygen, nitrogen, hydrogen, carbon dioxide etc. Ruslik_Zero 20:55, 28 April 2023 (UTC)[reply]

We have an article on theatrical smoke and fog which discusses how smoke effects can be obtained safely. Mike Turnbull (talk) 21:36, 28 April 2023 (UTC)[reply]

Burning itself tends to produce toxic chemicals. When you burn something organic at a few hundred degrees Celsius (like when people are smoking, or in a burning building), you get incomplete combustion, which produces a large number of different chemicals, many of which are toxic (expect some PAHs), along with some carbon monoxide. At higher temperatures and plenty of air, combustion tends to be more complete, but now you get NOx. PiusImpavidus (talk) 10:35, 29 April 2023 (UTC)[reply]

This being the Science desk, it intrigues me that Control of fire by early humans tells us that our ancestors have been deliberately using fire for maybe 2 million years, yet in modern times we seem to have discovered a lot of ways in which it does us harm. I would love to see discussion on those negative effects over those 2 million years. HiLo48 (talk) 00:44, 30 April 2023 (UTC)[reply]

Today's 8 billion people can produce a lot more smoke than 100,000 people could some 100,000 years ago. --Lambiam 05:01, 30 April 2023 (UTC)[reply]

Moreover, with the low life expectancy of early humans, the adverse implication of smoke breathing, aside from straight-out suffocation, were practically non-existent. Zarnivop (talk) 15:32, 1 May 2023 (UTC)[reply]

They also might have been smart enough to stay upwind. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:30, 2 May 2023 (UTC)[reply]

Some aerosols are not produced by combustion, though. David10244 (talk) 06:13, 30 April 2023 (UTC)[reply]

Neurology: How does a Lobotomy affect the Patients Religiousity ?

Well, the USA has practiced Lobotomy intensivly in the 50s and is also a very religious country. Also Medical sites are ofter Churchrun or even staffed by Nuns. This means, that a Patient who had a Lobotomy certainly has encountered Religion. Was there any Notable change ? As Lobotomy does (as Dr. Freeman himself putted it) "Smash abstract thinking", and abstract thinking is important for Religion, you would expect them to loose faith, or at least ignore abstract concepts like Trinity and focus on nonabstract things, like Crosses, Jesus and the like. However, a Lobotomy also may reduce intelligence, and the Churches are often into Antipsychiatry, so some might turn to Religion even more. Also, the most interesting Question is: Has a Lobotomy ever been performed on a Salafist (maybe in a black site ...) ? Since Salafists hate everything nonabstract, you would expect them to completely lose touch with Islam. --87.168.89.233 (talk) 20:50, 28 April 2023 (UTC)[reply]

The effects seen on people who survive the procedure are unpredictable and random, but generally not for the better. The impairment is often completely debilitating, requiring permanent care taking of the patient. --Lambiam 08:53, 29 April 2023 (UTC)[reply]

(Warning: My comment has little to do with the original question.) A fascinating read is My Lobotomy, by one Howard Dully, who was subjected to the procedure at a young age and managed to recover somewhat, possibly thanks to neuroplasticity. I picked it up in an airport just because it looked interesting. I was startled to recognize the description of the medical plaza where the operation was done — it was more or less in my home town, and I think I had medical appointments there as a kid. There seems to have been little justification for doing the operation on him even by the standards of the day. --Trovatore (talk) 19:18, 2 May 2023 (UTC)[reply]

May 1

Changing the speed of light, when the medium is not a perfect vacuum.

Is it possible to exert forces, on light moving in a medium that is not a perfect vacuum, for example in water, in order to change the speed of light in that medium?

If it's impossible, then why ? After all, as we know, it is possible to apply forces that slow down - or accelerate - massive bodies, so why is it impossible to apply such forces also to the light when it moves in water etc., so that the forces will make the light move (in water) at a slower speed, for example at the speed at which light moves when it's in glass? Or so that the forces will make the light move (in water) at a faster speed, for example at the speed at which light moves when it's in the air? 2A06:C701:747E:800:D855:A0F7:59BA:AFAB (talk) 18:35, 1 May 2023 (UTC)[reply]

So, the thing about all of the physics involved is that the speed of light is invariable, full stop. That's part of what general relativity says; any "acceleration" supposedly experienced by light (whether changing direction or speeding up/slowing down) is not an acceleration, it's spacetime curvature. Light being "slowed" in a material is due to interactions with the photons with particles of the medium, see Speed of light, to wit "This type of behaviour is generally microscopically true of all transparent media which "slow" the speed of light..." Light still travels in the space between, say, atoms and molecules, at the speed of light, however interactions between photons and the atoms themselves results in the apparent speed of light to slow, photons move in straight lines at the speed of light; however the apparent speed at which light waves move through a medium is slowed due to quantum interactions between the photons and the particles of the medium. When you say "the speed of light in water" what you are saying is "the speed light appears to move in water due to quantum interactions between photons and atoms" or some such, the light itself, insofar as it is actually traveling, still moves at "c". --Jayron 32 18:54, 1 May 2023 (UTC)[reply]

It is not completely true as speed of light in matter can exceed the speed of light in vacuum. Ruslik_Zero 20:13, 1 May 2023 (UTC)[reply]

What? it seems you confuse photons with electrons (in Cherenkov radiation). 2A06:C701:747E:800:D855:A0F7:59BA:AFAB (talk) 20:50, 1 May 2023 (UTC)[reply]

Well, that depends on your definition of "speed" and "light". At the most basic level, the photon can only travel through the quantum field at c. No faster, no slower. What we call light is, yes, photons, but it is also a more complex phenomenon that has several definitions of "velocity", such as phase velocity or group velocity. As a quantum particle (a disturbance in a quantum field), it can only move at the speed of c. --Jayron 32 11:08, 2 May 2023 (UTC)[reply]

Right, if you adopt the "path integral" or "sum-over-histories" interpretation of QM, you can think of photons being absorbed, emitted, and in between always traveling at exactly c. I think this is mostly of philosophical importance in this particular case; you would never actually calculate anything that way.

Alternatively, you can take the view that light in matter is not composed of photons but of polaritons, which do travel at sub-c speeds. --Trovatore (talk) 17:37, 2 May 2023 (UTC)[reply]

Fizeau experiment may be relevant. catslash (talk) 21:34, 1 May 2023 (UTC)[reply]

My point was only that you should be very careful when claiming that "the speed of light is invariable, full stop". It is only true in a sense that there is a fundamental constant called "speed of light in vacuum", which is of course is invariable. As to the real speed of electromagnetic waves in a medium - everything depends on the definition. Ruslik_Zero 20:23, 2 May 2023 (UTC)[reply]

Yes, but the OP is asking about exerting a force on light. What thing are we exerting a force on? A photon? Photons don't accelerate in any meaningful sense, they just move at c in a straight line. --Jayron 32 11:17, 3 May 2023 (UTC)[reply]

The speed of light (viewed as a wave phenomenon) in a medium (or in a vacuum) is set by the electric permittivity and magnetic permeability of the medium. To change the speed of light in water, you have to change those properties. It doesn't work by pushing it (although a change in pressure could change them, so that the index of refraction of ice is different from that of liquid water). You can push stuff which has mass and you could say that wet water has mass, but the matter is complicated as the mass of wet water depends on the energy. This speed of light in a medium, or more exactly the phase velocity of light, can be larger than the speed of light in a vacuum. The group velocity can't be larger than the speed of light in a vacuum.

How would you push light? When you push something to make it move faster, you perform work to add kinetic energy. We can do that with light by hitting it with charged particles; it's called inverse Compton scattering. Not easy to do in a dense medium. It leads to a change of frequency for the light, which may, in a medium, result in a change of velocity. For visible light in water, increasing the energy leads to a lower velocity. PiusImpavidus (talk) 09:33, 2 May 2023 (UTC)[reply]

However, see Superluminal group velocities and single waves wherever v=c carry energy and information. Modocc (talk) 11:54, 2 May 2023 (UTC)[reply]

May 3

Hum in headphone amplifier

I have a headphone amplifier that has some hum in it. If I put my hand on the metal case, the hum goes away - or at least so low that I can't hear it. Does it need to be grounded?

There is a post on the back for grounding it, but I don't know what to ground it to. Years ago I had my turntable grounded to a water pipe, when the pipes were metal. My current house has plastic pipes, so what can I ground it to? Run a wire to the actual ground? Bubba73 ^{You talkin' to me?} 04:03, 3 May 2023 (UTC)[reply]

It is most likely a ground loop problem. What are the headphones plugged into? USB? If it's USB, then the device itself needs to be grounded; if it uses a 2-prong adapter or something, then there's your problem. 136.56.52.157 (talk) 06:29, 3 May 2023 (UTC)[reply]

They are Audeze CRBN electrostatic headphones. Bubba73 ^{You talkin' to me?} 06:31, 3 May 2023 (UTC)[reply]

At that price point, you should contact customer service for tech support: [6]. 136.56.52.157 (talk) 06:40, 3 May 2023 (UTC)[reply]

P.s. this query from Audeze might be helpful, it suggests that it most likely relates to RFI. Not mentioned however, is that there are RFI filters for such problems. 136.56.52.157 (talk) 17:25, 3 May 2023 (UTC)[reply]

The hum goes away when I touch the metal case of the headphone amp, which is a Stax SRM-400S. Bubba73 ^{You talkin' to me?} 23:59, 3 May 2023 (UTC)[reply]

A couple a days ago I had this exact same issue with two guitar amps. Relocating the new amp from the campfire table to the bare ground stopped the 60HZ buzzing. Indoors, placing it on the floor reduced the hum only some, so I clamped a tape measure to it and wrapped that around a quart can of varnish I have. :-) Modocc (talk) 00:06, 4 May 2023 (UTC)[reply]

I'll try moving the cables and the amp around. Bubba73 ^{You talkin' to me?} 01:28, 4 May 2023 (UTC)[reply]

I think I'm going to try a ground-loop isolator, for the XLR inputs into the amp. Bubba73 ^{You talkin' to me?} 00:05, 4 May 2023 (UTC)[reply]

How did the ancients deal with mold and mildew in ancient aqueduct systems?

Modern drinking water systems rely on chlorine etc. to prevent mold from growing in water systems. Ancient aqueduct systems must have been exposed to the outside elements. Surely they would have accumulated mildew over time? Or did enough sunlight do the trick? Yanping Nora Soong (talk) 12:08, 3 May 2023 (UTC)[reply]

Does lead piping suffer from mildew? One just hopes it kills the bugs quicker than the humans! Martin of Sheffield (talk) 13:13, 3 May 2023 (UTC)[reply]

Pethaps continuously moving water is less prone to this (biologist required). A second hypothesis is that they didn't know or care about what was growing in their water supply. Dr John Snow was the first to realise that drinking water with sewage in it was a bad idea, and that wasn't until 1854. Alansplodge (talk) 13:56, 3 May 2023 (UTC)[reply]

Molds aren't the problem, bacteria are. And they aren't a problem within the system, but on either end. Abductive (reasoning) 15:36, 3 May 2023 (UTC)[reply]

Not an issue. As an example Plymouth's drinking water was supplied via leats which are large drainage channels that drain Dartmoor. They are effectively canalised streams. The water in them is entirely drinkable, if a bit tannic. Greglocock (talk) 20:38, 3 May 2023 (UTC)[reply]

One may discover, just upstream and out of site from where you quenched your thirst, a dead sheep in the leat. DuncanHill (talk) 20:47, 3 May 2023 (UTC)[reply]

Correct, which is why you walk downstream before drinking. Survival101. Greglocock (talk) 00:35, 4 May 2023 (UTC)[reply]

Images in Egyptian tombs from the 15th to 13th century BCE show various water treatment devices. An ancient Sanskrit text on medicine the Sushruta Samhita specified various methods such as boiling water under the sun and filtering it through sand and coarse gravel. Hippocrates c. 460 – c. 370 BC designed a crude water filter to “purify” the water he used for his patients. Later known as the “Hippocratic sleeve,” this filter was a cloth bag through which water could be poured after being boiled. Diophanes of Nicaea of the first century BC advised putting macerated laurel into rainwater, Paxamus proposed that bruised coral or pounded barley, in a bag, be immersed in bad tasting water and the eighth century Arabian alchemist, Gerber, described various stills for purifying water. Sir Francis Bacon in his compilation "A Natural History of Ten Centuries" 1627 discussed desalination and began the first scientific experimentation into water filtration. Philvoids (talk) 00:33, 4 May 2023 (UTC)[reply]

The best way to purify water is to warm it with some malt, boil it with some hops, let it cool and add the yeast. A few days later your water is fit for anyone! :-) More seriously, much weak ("small") beer was drunk prior to 20C just because it was safe, unlike the water supply from wells next to cess pits (see Alansplodge above. Martin of Sheffield (talk) 07:39, 4 May 2023 (UTC)[reply]

(Insert joke based on reading "20C" as a temperature in Celsius here.) --174.89.12.187 (talk) 18:17, 4 May 2023 (UTC)[reply]

(Point out that unlike 293K it would be 20°C.) Martin of Sheffield (talk) 19:38, 4 May 2023 (UTC) [reply]

20C??? That's a lot of electrical charge! 73.162.86.152 (talk) 06:42, 5 May 2023 (UTC)[reply]

Equivalent to downing 3-1/3 six-packs of Mountain Dew in a second. DMacks (talk) 06:51, 5 May 2023 (UTC)[reply]

May 4

Language and laugh

Why only humans have language?

And why humans laugh properly? Does humans have special ability in their tongue, throat, vocal cords?

Humans evolved in same environment with millions of species, so why can't animals have a language not just sounds. Some animals have bigger head than humans so their brain must have more capacity. If anyone checks brains of elephant, hippopotamus, great whale, what special thing is missing from their brain that human brains have? PatricSt (talk) 17:41, 4 May 2023 (UTC)[reply]

You could start by reading Origin of language. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:57, 4 May 2023 (UTC)[reply]

There is also an article titled Laughter which should answer many of your other questions. --Jayron 32 18:06, 4 May 2023 (UTC)[reply]

"The prefrontal cortex is commonly associated with cognitive capacities related to human uniqueness: purposeful actions towards higher-level goals, complex social information processing, introspection, and language."^[7] --Lambiam 20:12, 4 May 2023 (UTC)[reply]

May 5

Coal merchant occupational diseases

I've just finished an article on coal merchants, once one of the most common businesses but now much rarer. The Dutch Wikipedia article on the topic is totally unsourced but mentions that back and shoulder injuries were common because of the backbreaking work of carrying heavy sacks. Does anyone know if there's a source on this to add? (Yes, I know about chimney sweeps' carcinoma, but I don't think it's directly relevant.) And of course any other sources to improve the article would be much appreciated. Blythwood (talk) 11:18, 5 May 2023 (UTC)[reply]

I don't have a reference but I would imagine hauling heavy sacks of anything could cause back and shoulder injuries and this is just stating the obvious. I doubt you need a reference for that. That said, black lung disease may be of interest. "It is common in coal miners and others who work with coal." (Referenced.) 41.23.55.195 (talk) 12:31, 5 May 2023 (UTC)[reply]

I know about Wikipedia:You do need to cite that the sky is blue but gimme a break here. 41.23.55.195 (talk) 12:43, 5 May 2023 (UTC)[reply]

This article may be of interest (not sure how RS but it has a named author). Alansplodge (talk) 12:55, 5 May 2023 (UTC)[reply]

Not related to your question, but some images of coal merchants here, here, here and here. Alansplodge (talk) 17:45, 5 May 2023 (UTC)[reply]

Thanks so much to both of you! Will add the photos and that source. Currently thinking about a DYK hook. Blythwood (talk) 19:47, 5 May 2023 (UTC)[reply]

Pendulum Motion

Suppose a pendulum consists of a rigid slender rod. As the pendulum swings downward, the points closer to the free end of the rod are moving faster than the points closer to the fixed end, but all of the points are being accelerated by gravity at the same rate. I understand that gravity provides a torque about the fixed end, but somehow I can't intuitively understand what's allowing the points to have different speeds. Puzzledvegetable^{Is it teatime already?} 21:43, 5 May 2023 (UTC)[reply]

The gravity is applying a force to each part of the pendulum. But because it is rigid, there are forces withing the material called stress. This mostly counterbalances the force of gravity. It varies in strength and direction in different parts of the pendulum at different phases of the swing. Graeme Bartlett (talk) 21:50, 5 May 2023 (UTC)[reply]

Since the pendulum is a rigid body, gravity can be simplified to acting at the centre of mass. For a uniform rod this will be in the centre of the rod. Neglecting air resistance (probably not a valid assumption for a rod), then gravity acts on this centre and will vary from a maximum when the rod is horixontal to a minimum when it is vertical. Martin of Sheffield (talk) 22:12, 5 May 2023 (UTC)[reply]

The reason, though, this simplification can be made is due to forces acting within the rigid body, as indicated above by Graeme Bartlett. These internal forces counteract the effect of external forces (such as gravity) that threaten to shear it apart. If the stress (in the pendulum case more specifically the tension) exceeds a certain limit, it will still come apart. --Lambiam 06:29, 6 May 2023 (UTC)[reply]

May 6

Why is tungsten so cheap?

Why is tungsten so much cheaper than all the other noble metals like platinum and osmium? Or is it not that much cheaper and I'm just misunderstanding all the confusing price quotes that I find on the internet? They keep using different units for everything so I might just misunderstand them. – b_jonas 14:51, 6 May 2023 (UTC)[reply]

@@ Line 153: / Line 153: @@
 = May 6 =
+== Why is tungsten so cheap? ==
+Why is [[tungsten]] so much cheaper than all the other noble metals like platinum and osmium?  Or is it not that much cheaper and I'm just misunderstanding all the confusing price quotes that I find on the internet?  They keep using different units for everything so I might just misunderstand them.  – [[User:b_jonas|b_jonas]] 14:51, 6 May 2023 (UTC)