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June 5

Can releasing dragonflies cure malaria?

Would reproducing large numbers of dragonflies and releasing them into malaria-prone regions be sufficient to eradicate malaria and other vector-borne illnesses where the vector is mosquitoes? 2620:101:F000:740:D513:5A1F:346C:96F4 (talk) 01:01, 5 June 2019 (UTC)[reply]

Reduce, possibly. Eradicate, probably not. If a predator species were to entirely eliminate one of its prey species (which implies that it would at least severely reduce its other prey species as well) it would itself suffer a severe population crash if not local extinction. Predator-prey balances usually reach an equilibrium well short of eliminating the latter. Also, ecosystems are complex, and entirely eliminating even a human disease-carrying species might have unforseen deleterious consequences. {The poster formerly known as 87.81.230.195} 2.122.177.55 (talk) 02:02, 5 June 2019 (UTC)[reply]

An introduced species can completely eliminate a native species, especially if it also hunts other species, so can maintain its numbers even when the targeted species' numbers drop. If the predator was a native species, though, the target would presumably have evolved a method of survival (periodical cicadas have an interesting one). SinisterLefty (talk) 02:36, 5 June 2019 (UTC)[reply]

Dragonflies don't eat just mosquitoes, and chances are they would drive pretty much everything near extinction before mosquitoes. At which point, they will die out and mosquitoes recover faster than anything, and may even end more numerous than before. Look at predatory-prey relation and Competitive Lotka–Volterra equations

So, the short answer is: No. Gem fr (talk) 06:24, 5 June 2019 (UTC)[reply]

This has some interesting stuff about eradicating malaria. https://interestingengineering.com/fungus-modified-to-produce-spider-venom-that-could-be-used-to-kill-malaria-carrying-mosquitoes 196.213.35.147 (talk) 07:54, 5 June 2019 (UTC)[reply]

malaria has links to all fighting techniques. Besides, just like cancer, climate change, fuel scarcity etc., malaria tend to attract nutty "look, my favorite useless thing could be use to fight it" claims. Gem fr (talk) 09:48, 5 June 2019 (UTC)[reply]

DDT worked pretty well, but it had some side effects. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:39, 5 June 2019 (UTC)[reply]

WOW. What a splendid idea ... teach a fungus how to make one of the deadliest toxins in the world, then release mosquitoes exposed to it in a large area. But don't worry, the fungus will never make it through a double layer of mosquito netting... surely, granted extraordinary power to kill, it will never expand its host range, nor share its WMD knowledge with any other organism... what could possibly go wrong? Wnt (talk) 14:26, 5 June 2019 (UTC)[reply]

Thanks for the LOL (well, the matter IS serious, you made it funny)Gem fr (talk) 16:21, 5 June 2019 (UTC)[reply]

A pesticide analogy to ice-9. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:33, 5 June 2019 (UTC)[reply]

Because of the relative masses of a human versus a mosquito, the venom would have to be at something like a million times the concentration in the mosquito of what it would be in the human it injected ([1]), and then only if all the venom was injected. So, unless the human has an extreme allergy, such a low concentration shouldn't even be detectable. SinisterLefty (talk) 15:34, 5 June 2019 (UTC)[reply]

I hadn't been thinking so much of being bitten by the mosquito as being infected by the fungus. It only kills insects now, but if it now has a much-improved ability to kill other organisms (not necessarily large at first) then it should have the opportunity to evolve to make use of their corpses. Wnt (talk) 05:53, 6 June 2019 (UTC)[reply]

On further examination (i.e. asking my beloved Alexandra Elbakyan her opinion about https://science.sciencemag.org/content/364/6443/894.full ), also seeing some extra information at [2], it appears that the scheme is not quite as lunatic as I first thought. The toxin in question is omega/kappa hexatoxin Hv1a, which appears to be a small peptide with limited homology to the kind that is dangerous to humans, and is described only by citation to [3] (where it is one of several tested), which cites [4] which links structure [5] and thereby the amino acid sequence SPTCIPSGQPCPYNENCCSQSCTFKENENGNTVKRCD . The stability of the cysteine knot motif is described in this paper. You can argue that such a little scrap of data isn't going to affect humans even with some mutations (though it has structural homology, not much sequence homology, to human toxins), and I'd hope you're right, which may limit the risk more toward other insects. I am, however, still skeptical that funnel-web spiders evolved their toxin to kill malaria mosquitoes, and wonder how many amino acids would need to change for it to affect more organisms. Wnt (talk) 08:56, 7 June 2019 (UTC)[reply]

This reminds me of this theoretical analysis of engineered killer mosquitoes. They don't mention it in the paper, but they did make an unsuccessful attempt to actually engineer this into fruit flies. As to the original question, I honestly don't see anything wrong with it, except that "to extinction" is unlikely. Consider the sterile insect technique, where trillions of factory-bred sterilized males are released into the environment to overwhelm the local females with useless mating partners. If you had a predator of a pest species, and you could cheaply breed that predator on an industrial scale, so what if it eats the entire prey population? Good. I mean, if the predators are highly specialized, they just die out; and if they're not, but you sterilized them before they were released, the damage is limited until their lifespans run out; and if you didn't, but the prey are not native to this environment, they might just freeze to death in winter or something; and if none of that is true, okay, you have a new invasive predator population that's going to mess with the food chain. But then again, people have been so eager to eliminate some pests that they drained wetlands and bathed nations in insecticides, honestly believing any damage to the environment was worth it. I like to compare to that before deciding that something has an unacceptable cost or risk to the environment. Someguy1221 (talk) 23:04, 7 June 2019 (UTC)[reply]

Einstein's theories of relativity

What do Einstein's general and special theories of relativity state, in layman's terms? I've tried to understand them on my own by reading about them, but they're incredibly complicated to me. EonLinE (talk) 15:32, 5 June 2019 (UTC)[reply]

There's a lot to it, such as the time dilation near the speed of light, but as a practical matter, perhaps E=mc² is the most applicable to daily life. That says that energy and mass can be converted into each other, such as in a nuclear reactor or bomb, where some of the mass is converted into a huge amount of energy. SinisterLefty (talk) 15:39, 5 June 2019 (UTC)[reply]

I just see NO possible "layman's terms" for these theories. That are reasons why they are taught after extensive training in math and physics. Nobody knows that there WERE theories of physics (inherited from, basically, Aristotle) before Newton: we just have no need of them in the curriculum and it was much simpler to skip them altogether and go straight to Newton's. If the same could have been done (skipping Newton and going straight to Einstein), it would.

well, I do see some "layman's terms" for these theories, but I don't see how those will help you in any way. for instance: the universe is curved by the mass of things; so the light is always going in straight line; and gravitation is not about an attraction (distance effect) but rather a straight movement in a curved universe (local effect). Now, figuring a curved universe, where mass IS curvature...

May be you could try this http://www.savoir-sans-frontieres.com/JPP/telechargeables/English/everything_is_relative.htm ?

Gem fr (talk) 16:15, 5 June 2019 (UTC)[reply]

You can try Relativity for the Layman. Ruslik_Zero 19:21, 5 June 2019 (UTC)[reply]

The basic principles are actually fairly simple, though they're easier to grasp if you have some knowledge of classical mechanics. From our theory of relativity article, special relativity is based on just two axioms:

The laws of physics are the same for all observers in uniform motion relative to one another (principle of relativity).
The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the light source.

General relativity is based upon Einstein's equivalence principle: that being in a gravitational field is equivalent to being under acceleration. The "force" of gravity arises because mass and energy curve spacetime when present, and anything in that spacetime is compelled to follow the resulting geometry. All the predictions of relativity arise from just applying these principles. For more detail I recommend these videos on relativity from PBS Space Time (that channel is great for physics in general). --47.146.63.87 (talk) 19:48, 5 June 2019 (UTC)[reply]

Also, I'll link our introduction to general relativity just in case you didn't find it. --47.146.63.87 (talk) 02:58, 6 June 2019 (UTC)[reply]

In layman's terms, Special Relativity is stating the various consequences of the fact that light is measured to have the same speed no matter how fast you or the light source are moving (unlike say, a car on the highway, which seems to be getting closer or further from you at a rate that depends on your own speed), as well as the fact that basic the laws of physics you experience (think Newton and Maxwell) don't seem to change with how fast you are moving. General relativity is stating the various consequences of, basically, that plus gravity. In terms of equations, the special relativistic maths are mostly used to describe how things you observe seem to change depending on how fast they are moving relative to you. And the equations of general relativity define a relationship between the shape of spacetime on one side of the equation, and the stuff it contains on the other side (matter and energy). The shape of spacetime also defines how the stuff contained by spacetime moves and changes, which then dictates how the shape changes, so this becomes a continuous dynamic relationship. Basically, it lets a physicist predict how matter and energy move around over time, and how spacetime changes over time. These equations are absolute triumphs of what you can predict from a handful of assumptions, but they are not easy to understand. Someguy1221 (talk) 19:54, 5 June 2019 (UTC)[reply]

In lamyman's terms: you know how in olden days, people believed the Earth was flat like a pancake (i.e. 2 dimensional), but later they realized it was round like a ball (i.e. we still live on a 2-d surface, but it's a curved surface embedded in 3-d space)? Relativity is the same thing. We used to think space was 3-dimensional (flat and infinite in all directions), and the distance between two points was the Euclidean distance, the one you get from the Pythagorean theorem (sqrt(x^2+y^2+z^2)). Special relatively says no, we actually live in 4-dimensional spacetime, and the interval between two points uses the Minkowski metric t^2-x^2-y^2-z^2. Notice because of the subtractions, the whole thing can be less than zero if the space distance is large and the time interval is small. That isn't allowed to happen which means it's impossible to move faster than light.

General relativity says that 4-d spacetime is itself curved, and the curvature happens in places where mass is present, and gravity results from this curvature. By computing the curvature you can show effects like time dilation around massive objects like the Sun,o r even more extreme, around black holes. For a long time physicists calculated Newtonian predictions of the planet Mercury's orbit (using its distance from the Sun, the Sun's mass, etc.), and astronomers observed the orbit with telescopes and kept seeing a small discrepancy between the physicists' calculations and the actual orbit. GR was able to explain the discrepancy and how to compute it, and that was a big success that helped GR get accepted as a theory (see "perihelion of Mercury" section of tests of General Relativity).

You might like the old book Mr Tompkins in Wonderland which is about a guy entering a world where relativistic effects are big enough to be experienced in real life. 173.228.123.207 (talk) 20:48, 5 June 2019 (UTC)[reply]

A good book for the layperson was written by Einstein himself: Relativity: The Special and the General Theory, Wings Books, 1961 translation. Loraof (talk) 21:20, 6 June 2019 (UTC)[reply]

Electron Configuration

Determine whether the following electronic configurations are correct and explain your answer.

a. 1s22s32p63s1
b. 1s22s22p53s1

69.127.67.181 (talk) 15:41, 5 June 2019 (UTC)[reply]

We won't do your homework for you, but if you show us your answer, we might comment on it. SinisterLefty (talk) 15:50, 5 June 2019 (UTC)[reply]

Collapsing: drama far out of proportion of the initiating event. Tigraan^{Click here to contact me} 17:04, 6 June 2019 (UTC)[reply]

And it wouldn't hurt if you were to ask instead of issuing an order. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:49, 5 June 2019 (UTC)[reply]

the poster was simply stating the question he/she had been posed. No need to be hostile about it, or rabbit on further.80.2.20.209 (talk) 23:14, 5 June 2019 (UTC)[reply]

Hostility leads to more hostility. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:16, 6 June 2019 (UTC)[reply]

it seems you are looking for an argument?80.2.20.209 (talk) 01:29, 6 June 2019 (UTC)[reply]

No it isn't. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:36, 6 June 2019 (UTC)[reply]

Using imperative or demanding verbs "Determine!" "Explain!" is appropriate for issuing military orders, exercising authority or imposing an exam task (likely the case here) but is a jarring way to request free help from volunteers. The comment by Baseball Bugs was apt and needs no debate that can only distract from the good answers by Graeme Bartlett and Wnt. DroneB (talk) 13:05, 6 June 2019 (UTC)[reply]

WP:BITE? — Preceding unsigned comment added by 86.8.201.163 (talk) 00:25, 7 June 2019 (UTC)[reply]

Our article on this topic is Electron configuration. Graeme Bartlett (talk) 23:05, 5 June 2019 (UTC)[reply]

How many electrons fit in an s orbital? Can you fit more? How many electrons fit in the three p orbitals (x, y, z)? Can you fit less? That gets your answer. Note electrons can only fit in a single orbital together if they have opposite spins. Also, electrons can be "promoted" to a more energetic orbital by absorbing a photon. Wnt (talk) 11:12, 6 June 2019 (UTC)[reply]

ELECTRONS do not exist in orbials. ELECTRONS are pure energy. ELECTRONS may be given more energy, but that does not give them a larger radius of orbit. ELECTRONS do not orbit the nucleus. Otherwise they would emit em radiation. ELECTRONS are space charge existing some where remote from the nucleus. 86.8.201.182 (talk) 22:43, 7 June 2019 (UTC)[reply]

You aret confusing orbital with orbit. Electrons most certainly do have particle-like nature...they are not just photons. DMacks (talk) 03:38, 8 June 2019 (UTC)[reply]

And electrons aren't pure energy, in that they do have a (very light) rest mass. SinisterLefty (talk) 08:20, 8 June 2019 (UTC)[reply]

Does Diet Coke or Pepsi cause cancer

Does Diet Coke or Pepsi cause cancer due to aspartame or the coloring in the products — Preceding unsigned comment added by 64.222.180.90 (talk) 17:45, 5 June 2019 (UTC)[reply]

Our "aspartame" and "caramel color" (I assume that's the coloring additive) articles have substantial sections about the safety of these substances, with cites to reliable sources for further reading. DMacks (talk) 17:56, 5 June 2019 (UTC)[reply]

Quantum Encryption

In the WSJ of today there is a two page spread: "The Race to Save Encryption." by Christopher Mims. I am not sure he is in a position to understand the subject but this is what he says. The encryption algorithms of today that run on conventional computers may be made so complicated that only quantum computers might decrypt them. The latter could be made much-much smaller. There is an international race to develop a QC with China at the forefront and US and Russia trying to catch up. The development of QC might take at least 10 years or perhaps 20 or 30.

From what I carried away from reading on the matter in the past it seems that quantum communication is inherently safe and cannot be broken, I mean the messages cannot be intersected and understood, and they do not need any additional encryption. The author does not go into this subject at all. Could anybody shed light on the issue?

Thanks AboutFace 22 (talk) 19:05, 5 June 2019 (UTC)[reply]

I suggest that you read quantum cryptography. Ruslik_Zero 19:13, 5 June 2019 (UTC)[reply]

Quantum_computing#Cryptography is a lighter read. Tigraan^{Click here to contact me} 17:21, 6 June 2019 (UTC)[reply]

Pretty sure your suspicion about Mims is correct. Someguy1221 (talk) 23:43, 5 June 2019 (UTC)[reply]

There are two "quantum" issues that are closely related in their consequences but not so much related in their causes.

The first is whether current algorithms are "safe" against quantum computing. RSA is a widespread cryptography system and relies on the fact that integer factorization is much much harder than integer multiplication; however, it is not so with a quantum computer; same thing for a lot (all?) implementations of a Diffie–Hellman key exchange. The only saving grace for today's banking system, internet HTTPS connections etc. etc. is that making a quantum computer is hard, and has not been yet achieved (at least officially) at scales that allow integer factorization.

The second is about quantum-based cryptography. It turns out that commercial systems already exist that allow for communication of random data with no interception possible during transmission. The idea is that you share a random secret key on a channel whose physical properties guarantee that an interception attempt will be detected, and thereafter use that secret key for regular communication, changing it regularly. While a passive listener on the network cannot break that encryption (barring a seismic change in physics of far greater importance than finding a polynomial-time integer factorization algorithm), which is already huge, it does not mean it is entirely foolproof - if your computer is bugged, or if the random number generator that creates the key is compromised, then all bets are off. Tigraan^{Click here to contact me} 17:21, 6 June 2019 (UTC)[reply]

Entropy

What was the entropy the universe at the time of the big bang?. And has it increased or decreased in a linear fashion since then? Can we decrease entropy in the universe? If not, could it be zero at big bang time. 80.2.20.145 (talk) 22:33, 5 June 2019 (UTC)[reply]

It was very low at the start, the minimum. Entropy has increased since then. Take a look at The Entropy of the Universe and the Maximum Entropy Production Principle by Charles H. Lineweaver Graeme Bartlett (talk) 23:04, 5 June 2019 (UTC)[reply]

Origins

If our universe just created itself out of nothing and expanded into a nothingness that didnt exist yet as 'space' , then why can't other universes sprout up out of nothing as well? If these other universes can exist, then they must exist. So, if they exist, where are they hiding? Why can't we see them?80.2.20.209 (talk) 23:37, 5 June 2019 (UTC)[reply]

See Multiverse. If they existed and interacted with us, then presumably we would not exit. See also anthropic principle. One theory is that the big bang is a brane collision between two such "regions" -- Ekpyrotic universe. Graeme Bartlett (talk) 00:08, 6 June 2019 (UTC)[reply]

that's just the very definition of a "universe": if it can (or even just could) be seen by us, interact with us in any way (gravitation, for instance), it is part of the very same universe we belong, not part of another. Is it is part of another universe, there is no way we can "see" (physically interact) it. So, for every purpose, other universes, if any, just don't exist as far as we are concerned.

also, be aware that metaphysics allows things to be unique. For instance, in mathematics there is only ONE real line; it does have many ways to appear (to be constructed by mathematicians), but it is always the same good old real line, with no "other real line" hiding anywhere. So the fact that one exists is no proof that other all exist. Gem fr (talk) 05:33, 6 June 2019 (UTC)[reply]

Math does sometimes hint at hidden worlds. For example, the square root of 9 is typically considered to be 3, but another answer is -3. That's fairly obvious, but roots can also be complex numbers, which sometimes relate to the real world, but often do not, at least not in any apparent way. SinisterLefty (talk) 22:27, 6 June 2019 (UTC)[reply]

False vacuum might be relevant where anthropic principle is concerned. The linguistics are less interesting: other galaxies used to be called "island universes" in the old days. There will always be a temptation, when one's definition of the universe expands, to choose between logic and habit for what the term applies to; but it doesn't affect what's out there. Wnt (talk) 14:34, 7 June 2019 (UTC)[reply]

Each instant of time a new Universe. Count Iblis (talk) 20:37, 9 June 2019 (UTC)[reply]

June 7

Breakthrough Starshot Query

An extract from your article on Breakthrough Starshot reads; The Starshot concept envisions launching a "mothership" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude Earth orbit and then deploying them. A phased array of ground-based lasers would then focus a light beam on the crafts' sails to accelerate them one by one to the target speed within 10 minutes, with an average acceleration on the order of 100 km/s² (10,000 ɡ).

Many scientific minds have been involved in the development of this idea, but I just can't understand how a ground-based laser could remain in the ideal position for 10 minutes to accelerate one of these "Star chips" exactly towards a galaxy 4.37 light years away. Surely the rotation of the earth would move the laser "sideways" off target in a matter of seconds? Any enlightenment on this would be most welcome! 49.197.104.112 (talk) 06:32, 7 June 2019 (UTC)[reply]

I confess not understanding it all, but the problem you envision seems no problem to me. Taking care of the rotation of the earth is one of the job of a telescope mount. Gem fr (talk) 06:47, 7 June 2019 (UTC)[reply]

In science fiction everything is easy ;). But yes you'd steer the beams to compensate for the earth's rotation and also for atmospheric turbulence. Or you could bypass the latter problem by putting the lasers in space or on the moon. 100GW though? And getting that gossamer sail to survive 10,000g of acceleration? Good luck with that ;). 173.228.123.207 (talk) 06:53, 7 June 2019 (UTC)[reply]

(OP) Thanks, but keeping the beams pointing at the Starchips as the Earth rotates doesn't accelerate them towards their target49.197.104.112 (talk) 07:34, 7 June 2019 (UTC)[reply]

Laser propulsion is the article explaining how a laser could give the desired acceleration (see also: solar sail) Gem fr (talk) 08:07, 7 June 2019 (UTC)[reply]

Enough light to accelerate something at 10,000 g, sustained for 10 minutes? I don't think I appreciated the scale of the project. That is a big honkin' space gun. Also the sail, to avoid being vaporized, must reflect the light nearly perfectly, which I think means that if you make it flat enough, that is a big honkin' space gun that could be reflected and aimed back at targets on Earth. I think I begin to see the reason for the idea's popularity. Wnt (talk) 09:04, 7 June 2019 (UTC)[reply]

considering the mass m of the thing to be accelerated (cm size -> gram mass; pretty much the same as a bullet) we are talking of force=a/m of a ten to hundred Newton magnitude, and power=F.v 100.60,000,000 ~ 1-10 GW range. (unless I made some mistake). So, yes, this is the magnitude of laser weapons currently developed. Gem fr (talk) 19:58, 7 June 2019 (UTC)[reply]

Breakthrough Starshot is the article in question. Could the angle of the sails be adjusted to compensate for the slight change in the angle of the incoming laser beam ? But either a laser in Earth orbit or on the Moon would seem to make more sense. Both have the advantage of no atmosphere to deal with, while Earth orbit has the advantage of being easiest to reach, with the right orbit being able to eliminate the Earth's rotation as an issue. The Moon has about 1/28th the Earth's rotation, but has the advantage of slight gravity, making working on the laser simpler (no tools and screws and astronauts floating away), and you don't have to worry about orbital station-keeping, and sensitive equipment (power source, spare parts, etc.) can be placed underground to protect it from gamma rays, etc. If this laser is to be a long-term investment, then the Moon may be a better option, especially if a nuclear reactor is to power it all, which we really wouldn't want in Earth orbit. That way, the nuclear waste could just be left on the Moon. SinisterLefty (talk) 12:12, 7 June 2019 (UTC)[reply]

The whole point of the system is to have the power source on earth, so you don't need to put it on orbit Gem fr (talk) 19:58, 7 June 2019 (UTC)[reply]

Dealing with the atmosphere alone seems to make this impractical. SinisterLefty (talk) 20:01, 7 June 2019 (UTC)[reply]

Surely atmosphere is a problem, but current telescope technology seems to have solved most of the issues by using proper location and ... lasers. Gem fr (talk) 08:49, 8 June 2019 (UTC)[reply]

Adaptive optics can somewhat reduce the problem, but not solve it entirely. Otherwise, there wouldn't be any point in space telescopes like Hubble. And if the cost was less, we would presumably have far more space telescopes. But, in the future, we can predict that the cost of space launches will come down, now that we are starting to see the commercialization of space launches, with SpaceX and such. SinisterLefty (talk) 22:49, 8 June 2019 (UTC)[reply]

for the point of a space telescope, see Hubble_Space_Telescope#Successors. Many reasons wont apply to a laser, and you have to consider the problem of the huge power source Gem fr (talk) 23:07, 8 June 2019 (UTC)[reply]

If we were talking about making this today, then yes, a much larger Earth-based laser would make sense. But as the rest of the technology for this project seems decades away, when the cost of space launches will be far lower, that logic will no longer apply. I can also predict a time when Earth-based telescopes will be considered obsolete, except for hobbyists, with serious science all using space-based or Moon-based telescopes. Manufacture of the mirrors, lenses, etc., in space would also eliminate any distortions introduced by gravity. SinisterLefty (talk) 03:39, 9 June 2019 (UTC)[reply]

(OP) Would a laser of that power output have an "opposite and equal reaction" ?? ie if you put it at a Lagrange point, would the reaction from the power output force it back in the opposite direction? Also I think that a sail restrained only around the edges could never stay flat enough under that incoming power to reflect a coherent beam back to earth.49.197.104.112 (talk) 00:09, 8 June 2019 (UTC)[reply]

Yes on the equal and opposite reaction, but if the laser unit has a mass a billion times that of the target, it would only be subject to a billionth the acceleration of the target, assuming 100% efficiency. Still, some orbital station-keeping would eventually be required, hence the advantage of placing it on the Moon. The L1, L2, and L3 Lagrange points are stable in one direction (towards the line connecting the Earth and Sun), so will tend to fall back towards that line, but are unstable in the other direction, towards or away from the Sun and Earth. So, if you could arrange it so the push was in the right direction, it's possible that the laser unit might find a way back to the Lagrange point by itself. But this turning out to be the push direction you want would require quite a coincidence. SinisterLefty (talk) 08:35, 8 June 2019 (UTC)[reply]

Unruh effect - simulation or confirmation?

Any commentary on [6] would be welcome. Our article on Unruh effect says it "may" have been observed in 2017; this article says it hasn't been, but now it's been simulated in a Bose-Einstein condensate with magnets. Are the magnets accelerating the atoms or not? The coherence means it's quantum, what does that mean? Etc. Wnt (talk) 14:29, 7 June 2019 (UTC)[reply]

This is, of course, a simulation, not a confirmation. Ruslik_Zero 15:54, 7 June 2019 (UTC)[reply]

Alright, let's go to [7]. It says "By modulating the magnetic field at frequency ω near a Feshbach resonance, a jet-like two-dimensional emission of atoms with momentum k_f = √mω/h observed few milliseconds after the modulation, where m is the atomic mass. Such emission forms a fluctuating bosonic field, also called “Bose fireworks”, and is a result of bosonic stimulation." That sounds sort of like real acceleration to me, which is one of the many reasons why I'm confused. Wnt (talk) 18:51, 7 June 2019 (UTC)[reply]

Vocal range in human (speech, not singing)

What is the (realistic) vocal range in women for ordinary speech? I understand there are some very rare exceptions, but what is more or less reasonable to assume?

I came across the claim in the Elizabeth Holmes article: ″During most of her public appearances, she spoke in an unusually deep baritone voice, although a former Theranos colleague later revealed that her natural voice was actually a few octaves higher.[15]″ - Is it realistic that a woman has a vocal (speech) range containing a few octaves and still sound more or less natural in her low- (baritone) and her high-pitched speech? I've only found the articles on vocal range and voice classification in non-classical music so far, which seem to be restricted to singing. Am I overlooking a more relevant article? --Ibn Battuta (talk) 22:05, 7 June 2019 (UTC)[reply]

The article is nonsense so far as evidence goes. Even if we take a low value for 'a few' as 2 then the difference of 2 octaves uses up a signficant pert of your range. I could maybe believe half an octave. Greglocock (talk) 22:27, 7 June 2019 (UTC)[reply]

The article editor(s) should try to find some clips of Tallulah Bankhead. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:51, 8 June 2019 (UTC)[reply]

I've heard some high-pitched women speakers who I think routinely speak in an upper register that I thought til just now was falsetto, but the falsetto article says the actual falsetto mechanism is different from what I thought. Anyway that register can easily be an octave or more above the lower part of the modal register. The vocal fry article has an interesting paragraph:

Some evidence exists of vocal fry becoming more common in the speech of young female speakers of American English in the early 21st century,[4][5][6][7][8] but its frequency's extent and significance are disputed.[9][10] Researcher Ikuko Patricia Yuasa suggests that the tendency is a product of young women trying to infuse their speech with gravitas by means of reaching for the male register and found that "college-age Americans [...] perceive female creaky voice as hesitant, nonaggressive, and informal but also educated, urban-oriented, and upwardly mobile."[4]

So maybe that's what Holmes was doing. 173.228.123.207 (talk) 08:21, 8 June 2019 (UTC)[reply]

Well, the link would be Falsetto#Use_in_speech, but the article does not look in great shape.

Basically, the articles about singing apply, since one can speak at any pitch that one can comfortably sing, as long as one is used to it. I would imagine EH decided that speaking with a lower pitch would project gravitas and was worth training.

Assuming [8] is a representative excerpt, she does not use vocal fry. It is probably the lower end of her modal range (still much higher than a baritone voice in terms of frequency even if the voice "sounds" similar). My OR from practicing classical singing (which, in addition to being OR, is likely to be a biaised sample since it covers trained singers) is that almost all men (90%+?) speak at pitches very close to the lower end of their tessitura (a couple of tones above it at most), but there is more variation in women (maybe because of the easier falsetto transition?). Tigraan^{Click here to contact me} 08:06, 10 June 2019 (UTC)[reply]

Audio anplifier

How much louder is a 300w amp than a 100w amp?. And why do amp manufacturers emphasise the wattage above anything else? 86.8.201.182 (talk) 22:49, 7 June 2019 (UTC)[reply]

I mean, could I detect the difference,? 86.8.201.182 (talk) 22:51, 7 June 2019 (UTC)[reply]

About 4 or 5dB. Depends a lot on the definition of "Watt" and how relatively honest each manufacturer is. Also a larger amplifier into the same speakers will be less effective (electrical power to loudness tends to be more efficient at lower levels for the same speaker).

3 dB is a doubling of power, and is considered to be the increment that's easily discernible to the listener. So yes, you'll hear it.

Watts are easier to measure. They're also an attribute of the amplifier alone, not the amplifier and speaker combination. Andy Dingley (talk) 22:57, 7 June 2019 (UTC)[reply]

Also, if the speakers can't handle 300 watts, there would be some rather noticeable distortion and possibly blown speakers. SinisterLefty (talk) 23:42, 7 June 2019 (UTC)[reply]

June 8

Xylocopa pubescens carpenter bee.

I recorded sounds emitted from a nest of Xylocopa pubescens carpenter bee.

Any information concerning the exact nature of these sounds will be appreciated. Etan J. Tal^(talk) 19:44, 8 June 2019 (UTC)[reply]

sounds like squeaking, produces by friction, this friction being caused by the movement of the bee Gem fr (talk) 20:41, 8 June 2019 (UTC)[reply]

Mechanics of gas powered rotary cannons

There is a lot of material about the mechanics of electrically powered rotary cannons (e.g. Minigun), but i can't really find any information about gas powered ones (e.g. GSh-6-30). How do they actually, mechanically work? Do they have some sort of gas piston, that cycles the weapon in discrete steps for every single shot, similar to standard machine guns? Do they have a gas turbine, that just sets the barrels in motion like an electric motor does? Something else?

I can only find find sources saying something like "the russian gatlings are gas powered, so they fire faster." But why do they? --178.4.77.247 (talk) 20:45, 8 June 2019 (UTC)[reply]

They're gas operated. Gas from the fired barrel is tapped off and works a piston in the cylinder on the side of the frame. This piston has a rack and pinion gear on it, which drives through a short radial shaft to another pinion, which works the radially-toothed ring gear you can see here. That drives the barrel frame around. The piston also cocks the action. A further ring gear and pinion (parallel teeth), also visible here, drives the feed. You can also see the piston return spring here, which is a twisted wire helix. They're prone to failures and the multiple wires keep the action working even if one strand fails.

Compared to the US weapons, the drive is more powerful and so it accelerates to full firing rate more quickly (useful for air combat). However it's too powerful, there's insufficient damping or end stops, and it shakes airframes to bits. The naval mounts are much more robust and survive by sheer Soviet brute force. What it really needs is a gas valve which would reduce the power once up to speed. Andy Dingley (talk) 21:09, 8 June 2019 (UTC)[reply]

Thanks a lot! This is much more information than i've found through Google. I would suggest to also put it onto the GSh-6-30 article.

If i may risk some speculation, could my idea of a turbine powered gatling possibly work? It should solve the problem of the piston hammering the mount. Also, like with electric motors, as the barrels spin freely they should be able to eject some misfired catridges without stopping the gun. But i guess it might need a kickstart to get the ROF high enough to sustain operation. --178.4.77.247 (talk) 22:00, 8 June 2019 (UTC)[reply]

Turbines are naturally best for low torques at high speeds – which isn't what a firearm needs, at least not for starting. The piston mechanism (which is used in every gas-operated weapon) is a better impedance match (ratio of force or torque and speed) to what's needed here. But it's a bit crude for secondary effects, such as the vibration. No doubt it met someone's Five Year Plan, and that's the Soviet way. Andy Dingley (talk) 23:00, 8 June 2019 (UTC)[reply]

June 9

Space-based solar power

Would a Molniya orbit be suitable for a (theoretical) space-based solar power plant? 2601:646:8A00:A0B3:E143:3EF:8DB:B5B7 (talk) 01:37, 9 June 2019 (UTC)[reply]

As described in space-based solar power, most proposals have the transmitters in geosynchronous orbit, where they will see the sun ~99% of the time and aiming at the receiver is relatively easy. However, further down in the "non-typical" section, it also describes and links to a proposal for using more exotic orbits, including Molniya, in part because it could be relatively cheaper. Someguy1221 (talk) 02:07, 9 June 2019 (UTC)[reply]

Transmitting the power back to Earth seems impractical, as whatever the gain is from placing the solar panels in space (subtracting the losses of transmitting through the atmosphere), that gain can't possibly be worth the extreme cost of placing the solar panels there. That is, you could just use a small fraction of that money to place far more solar panels and energy storage facilities on Earth. Of course, eventually the space costs will come down and we may run out of places to put solar panels on Earth, but by then hopefully we will have fusion reactors working. So, solar panels in space really only make sense for powering devices right there (which does include sending signals back to Earth). SinisterLefty (talk) 03:28, 9 June 2019 (UTC)[reply]

At microwave frequencies the atmospheric absorption is considered not that bad. There are all kinds of artist conceptions of cows grazing under the ground antennas, planes flying through the microwave beam without the aircraft or passengers being heated, etc. There is math behind all of it but I have to wonder about public acceptance if the schemes got anywhere near practicality and someone wanted to actually launch them. The lyrics of Home on Lagrange allude to this. 173.228.123.207 (talk) 05:48, 9 June 2019 (UTC)[reply]

someone wanted, a century ago. It failed. Wireless_power_transfer#Tesla Gem fr (talk) 11:39, 9 June 2019 (UTC)[reply]

Transmitting the power back to Earth IS impractical indeed, and, moreover, the energy cost to send things in orbit is so great it kills the payback. But we also need energy in space. So, maybe, for space application? Gem fr (talk) 11:39, 9 June 2019 (UTC)[reply]

Absolutely, solar panels are widely used to power satellites and space ships, at least in the inner solar system. But whether it would ever be practical to send solar power from one collecting station to a remote location, both in space, is questionable. What would be the advantage, instead of just attaching the solar panels directly ? If there are no big advantages, then it just adds complexity, inefficiency in changing energy forms, and potential for accidents, for little benefit. I suppose one advantage would be that the solar collector could be in an orbit that never or rarely passes into the Earth's shadow, but just tripling the size of the solar panels on the station using the power (which does pass into the Earth's shadow), and adding some batteries, might be a more practical fix. However, if the remote station is used, perhaps just using mirrors to aim light at the destination's solar panels when it's in shadow (or even to boost power when it's in light) would be the simplest fix. SinisterLefty (talk) 13:19, 9 June 2019 (UTC)[reply]

More (well, OK, less) to the point, following the logic above, why doesn't Earth send the power to space routinely? I'd think that, apart from backing up the most critical systems, a satellite could use that same power transfer tech to get a signal, especially since it would unfurl a very light net of delicate antennae a long way. Wnt (talk) 14:33, 9 June 2019 (UTC)[reply]

What would be the advantage ? Any device designed to receive the power source on the satellite would likely weigh as much as the solar panels. And then bad things might happen to planes flying through the power stream, so you'd probably need to put it on top of a mountain to minimize that risk (and atmospheric scattering), with high associated costs. And unless the satellite was in geostationary orbit (rather distant and directly over the equator), it would lose the power stream at least as often as it would lose sunlight. SinisterLefty (talk) 17:30, 9 June 2019 (UTC)[reply]

current solar panel don't have impressive power-to-weight ratio: ~100 W/kg. And, funnily, one of the best way to transmit power to space seems to make use of... solar panel (the source is a laser instead of the sunlight); efficiency is greater, and it can be more intense that the petty 1kW/m² of the sun. Now, any risk to lose power is a no-no, and you don't want to rely on heavy batteries or fuel consuming device, so, self-power it (currently) is. Gem fr (talk) 18:43, 9 June 2019 (UTC)[reply]

The power-to-weight ratio is infinite, since it's weightless while in orbit. :-) But seriously, the entire lifespan of the solar panels should be considered, so we look at power generated over the entire lifespan (kWh, for example) divided by mass. Batteries, voltage converters, etc., should be included. For the alternatives, like nuclear power, the fuel and all the equipment and shielding would need to be considered. If the satellite or ship mission is only planned for X number of years, then the calculations should only take that amount of time in consideration. SinisterLefty (talk) 00:43, 10 June 2019 (UTC)[reply]

Proposals for solar power satellites that I remember involved making the solar panels from lunar material so there was no need to launch it from Earth. Laser propulsion has been proposed as a way to launch spaceships, possibly using light sails. But a high powered microwave beam could be hard to focus on a geostationary satellite. You'd need multiple ground stations, etc. The hope of spaceflight buffs was to just make launching stuff to LEO a lot cheaper, and have high efficiency space tugs to move stuff to GEO. Project Orion (nuclear propulsion) was the most extravagant of the cheap launch schemes. "We could have brought barber chairs" is the quotation I remember. 173.228.123.207 (talk) 23:04, 9 June 2019 (UTC)[reply]

Yes, moving production to the Moon would be one necessary step, but to bring the production costs down, the system has to be highly automated, so we don't need the expense of sending people there, and ultimately we need self-replicating robots, so we don't need to keep sending them there, either. All this is decades or perhaps centuries off, though. SinisterLefty (talk) 15:38, 10 June 2019 (UTC)[reply]

[un-indent] Folks, let's not get sidetracked here -- I was asking about the advantages and drawbacks of a Molniya (or better yet, Tundra) orbit compared to the traditional proposals for solar power in equatorial orbit (presupposing for the sake of the argument that space-based solar has become feasible, which IRL it hasn't), not about the feasibility of space-based solar power as such! 2601:646:8A00:A0B3:C5E:C820:3A44:3500 (talk) 01:04, 11 June 2019 (UTC)[reply]

hum, sorry for the sidetracking. Satellites on those orbit have a changing position and a changing distance to a station on Earth, and, unless I am mistaken, a higher energy cost than on a geostationary orbit. All this rank as drawbacks, while i struggle to see any advantage. If such a power plant were to exist, it most sensible and first use would be to power space objects, and for that, you don't need geosynchonism, but rather synchronism with the objects to be powered, that is, a lower, less costly, orbit. Gem fr (talk) 17:08, 11 June 2019 (UTC)[reply]

bird net around wind turbine?

Would it be that difficult/costly to cover wind turbines with nets to prevent them killing birds and bat? Any idea why this is not done?Gem fr (talk) 18:54, 9 June 2019 (UTC)[reply]

How fine would the mesh need to be? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:21, 9 June 2019 (UTC)[reply]

Just like nets used as pest control for orchard, I guess. Gem fr (talk) 20:04, 9 June 2019 (UTC)[reply]

Googling "bird friendly wind turbine" yields a number of theoretical and practical approaches. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:30, 9 June 2019 (UTC)[reply]

indeed, but saw only designs that, for all practical purpose may solve the issue in the future. And I never saw nets mentioned. There must be some reason Gem fr (talk) 20:04, 9 June 2019 (UTC)[reply]

What's the business case? Mostly, anything that reduces the efficiency of the turbines would need a good business argument (e.g. reduces bird strikes by X% which in turn reduces maintenance costs by £Y million, at a cost of £Z million in the reduction of electricity generated). If it was good business sense to do so, it would be happening already. The Rambling Man (talk) 20:09, 9 June 2019 (UTC)[reply]

It obviously cost something to prevent bird kills. And it seems that it was cheaper (better business) to convince administration to turn a blind eye on those kills. Now, what if the administration required those safety net, so the business had no choice? would that kill it, or just imperceptibly dent profits? Gem fr (talk) 20:36, 9 June 2019 (UTC)[reply]

I don't think for a moment that wind turbine operators care about the death of birds, just the ability to maintain turbines creating as much electricity as possible. Putting a net around the turbines (and I'm still unclear as to how that is possible) would inevitably cost money and reduce efficiency. It's obvious that the payback in reduced maintenance is not worth it. Hence they don't do it. The Rambling Man (talk) 20:39, 9 June 2019 (UTC)[reply]

I think you have more faith in the intelligence of business people than I do. :-) But I share your curiousity in how such a thing would even work. Would they essentially all get turned into box fans? Matt Deres (talk) 20:58, 9 June 2019 (UTC)[reply]

boxed fan, yes, that's the idea. although maybe just covering the most dangerous part (the tip) could be enough (again: if possible and if this doesn't make thinks worse, which could be. I don't know, hence the question) Gem fr (talk) 07:54, 10 June 2019 (UTC)[reply]

Maybe it would make sense in the rare case of a bird nearing extinction being threatened by a wind farm. But, in general, the surviving birds will learn to avoid turbines, just as the surviving varmints learn to avoid being hit by cars. SinisterLefty (talk) 00:39, 10 June 2019 (UTC)[reply]

This article claims windmills kill far fewer birds than most people think. It cites this article (paywalled), which claims that, per unit of energy generated, fossil-fueled power stations kill something like 15× as many birds. Adrian J. Hunter^{(talk•contribs)} 00:59, 10 June 2019 (UTC)[reply]

Unfortunately, from a publicity POV, the windmills are worse. That is, if they can install a camera to monitor a turbine, and capture a bird being sliced in half, and put that on the news, that will garner far more outrage than if 15 birds, miles from the coal-fired plant emitting pollution, die from no apparent cause. Even worse, those plants also kill many people, but it's never obvious who would have lived had the air been a bit cleaner. SinisterLefty (talk) 15:31, 10 June 2019 (UTC)[reply]

The fact that no such video ("killer windmill brutally slices cute seagull in half") has been produced yet, despite political incentive to do so, tells you enough about the frequency of such incidents. (Also, as the original article (paywall) says, not all mortality is not due to gruesome slicing: there are also collisions with static parts, electricity lines etc.). Tigraan^{Click here to contact me} 10:36, 11 June 2019 (UTC)[reply]

Any bird that manages to kill itself by flying into a stationary object deserves the Darwin award, for improving the gene pool. :-) SinisterLefty (talk) 17:53, 11 June 2019 (UTC)[reply]

As others have brought up, lots of man-made things kill more birds, and often more graphically. (Environmental impact of wind power has a table.) Bird strikes are a constant issue for aircraft, and there are plenty of videos of them, but there doesn't appear to be any big movement to ban or heavily restrict aircraft. Many have argued (example) that the concern about windmills and concentrated solar power killing birds is really just NIMBYism. People don't want the things built near them, and then they look around for other justifications to try to sway people, and choose the impact on charismatic megafauna as one. --47.146.63.87 (talk) 00:10, 12 June 2019 (UTC)[reply]

There is experience of audio and visual means of scaring birds away from airports. A loudspeaker mimics actual bird distress calls or makes frightening noises. It can broadcast species specific distress cries that scare flocks away. Visual deterrents, such as representations of owls and other natural predators, frighten birds away.See Bird control for airports. Special measures that can be employed include lasers, drones and radio-controlled hawks. DroneB (talk) 15:59, 10 June 2019 (UTC)[reply]

June 10

Share a submitted paper with colleagues

Hi; I have submitted a paper to a peer-reviewed journal which is now currently under revision (no decision yet) - a potential employer would like to see the draft now as part of the recruitment process, however, I know of their own strong science department and am now slightly afraid of sending them the draft. What are your take on this - any way to protect my intellectual property prior to the publication? Thank you in advance! --5.151.0.126 (talk) 19:47, 10 June 2019 (UTC)[reply]

You have evidence/proof that the paper is your own and the journal's records can corroborate that if you'd ever need to make an intellectual property claim. Sending drafts of papers is common practice when applying for jobs, so I would not be too worried about it. EvergreenFir (talk) 20:36, 10 June 2019 (UTC)[reply]

Trap street? Introduce a few small typographic errors in your literature citations, the DNA sequences of your constructs, whatever is relevant to your situation and seems most likely to be used in a plagiarized version. Scan the paper, calculate a checksum and post it to some dated online forum like Github, Usenet, Twitter, whatever. Or do something more professional to archive the version. If the paper gets published with the trapped information, you have them by the short-and-curlies. But my impression is you need contacts involving some kind of "fixer" along the lines of Michael Cohen's dealings if you intend to arrange to blackmail them in a way that is legal and professional, and that I don't know much about. Wnt (talk) 03:12, 11 June 2019 (UTC)[reply]

First of all, check with your co-authors, university etc. that you are allowed to share the draft. (Most likely that is not a problem - information that you are about to publish is no longer confidential - but you do need to check beforehand.) A group email would do.

Look at recently-published articles of the journal you submitted to. If articles have a mention of the date of submission, you have a proof of priority if it comes to plagiarism accusations (you certainly do not want to go there, but si vis pacem para bellum - the mere existence of such documentation will deter unscrupulous parties). (Almost?) all Elsevier and SAGE journals publish such mentions (received, revised, accepted, published dates); I would expect all editors that are not staggeringly incompetent keep that information internally anyway.

There are horror stories about reviewers stalling the peer-review process while whipping their own PhDs/postdocs to reproduce the same results and publish in a concurrent journal (stealing the experimental methods if not the actual data and article), however that is probably not a real issue for you, since (1) it is extremely rare, (2) it relies on the reviewer stalling publication (which they have no reason to do if they are a uninterested third party), (3) you are at the revision stage, so they already lost a couple of months if they wanted to pull that maneuver, and (4) presumably they are not as specialized in your paper's topic than a reviewer would be.

A more significant risk than plagiarism is that they are pulling a scam to get a copy of your paper (free of charge and ahead of publication). I would say it is an acceptable risk to take - assuming a research-related position, a draft paper would unquestionably be useful to evaluate your candidacy, and the information you share is something that would go public anyway. If they start asking about confidential information during the interview (your laboratory's internal procedures, procurement chains, etc.) at the interview, that is a much bigger red flag. Tigraan^{Click here to contact me} 10:28, 11 June 2019 (UTC)[reply]

Poor man's copyright doesn't seem to work in the USA. It does in other juridictions Gem fr (talk) 10:32, 11 June 2019 (UTC)[reply]

Most journals allow (and sone require) pre-publication of your draft on something like arXiv. That would take care of precedence and allow you to share it with your potential employer. On the other hand (being in a comfortably secure position), I would seriously think if I want to work for an employer whom I distrust in such a basic matter. --Stephan Schulz (talk) 14:43, 11 June 2019 (UTC)[reply]

Preprint server like DSpace or arXiv. Andy Dingley (talk) 19:46, 12 June 2019 (UTC)[reply]

June 11

Drunkenness before alcohol

It has long been my impression that I'm rather susceptible to "contact high", especially where alcohol is concerned. When I was a little kid, before I ever had heard of the idea, a couple of glasses of wine to the adults would nonetheless make me rambunctious. One time later on I recall a time when I simply blundered into a group of college students coming out of a sports game and not merely felt drunk from being with them but was literally unsteady on my feet for a bit. Now one possibility is I'm E.T., but more likely is that there's some psychological state of inebriation, which a person can be brought into by social cues, or which can be triggered chemically. According to this model, early man would have developed a tendency to party in a drunken way, perhaps not dissimilar from some of the orgiastic rites recounted the world over where people use things that aren't alcohol and don't seem inebriating to some impartial observers, ranging from invocation loa spirits to kava-kava, to achieve something akin to alcohol inebriation. Alcohol might trigger that accidentally, or perhaps the profuse availability of near-rotten fruit created a situation where it was beneficial for early man to drop everything and hang out on the ground swapping stories and munching, to the point where the propensity to drunkenness literally evolved. Contact high would then result from a strategic requirement for such a state to be widely shared among participants, a sort of social peace treaty where people would somewhat let down their guard to enjoy a common feast.

But is there anything to back up such an idea? Has anyone demonstrated a state of drunkenness without alcohol from some festivity by fMRI, or observed primates acting oddly while enjoying the end of a fruit harvest? It's kind of an annoying thing to search for because of all the more practically oriented alcohol research. Wnt (talk) 09:52, 11 June 2019 (UTC)[reply]

If I recall correctly, a state of drunkenness without alcohol from some festivity is often associated with the release of endorphines to the brain (that's why we're a bit looney when enjoying something). Also, alcoholic vapors produced by a drunken person towards some susceptible sober people may play a role - this is the principle a breathalyzer is based upon. Brandmeister^talk 14:12, 11 June 2019 (UTC)[reply]

I googled "placebo drunkenness" (a slightly different concept to what you're describing) and found this 2003 report on BBC news, as well as a couple of academic articles. AndrewWTaylor (talk) 14:23, 11 June 2019 (UTC)[reply]

Only a hypothesis, but it's possible that it also has to do with nonverbal communication. I failed to find exactly the term I was looking for, but a common aspect is involuntary mimicry (of facial and body expressions, language accent, etc)... —Paleo Neonate – 14:33, 11 June 2019 (UTC)[reply]

There's a somewhat disputed theory of mirror neurons that might figure into this. 67.164.113.165 (talk) 10:13, 12 June 2019 (UTC)[reply]

gluing together two parts of a broken stone (limestone)

The following question is destined to the those who have the knowledge or the skills: what's the right way to glue two parts of a stone, that has broken up into two pieces as a result of a hit ? what material/s are recommended for that purpose ? Thanks, בנצי (talk) 10:08, 11 June 2019 (UTC) השאלה מיועדת לבעלי ידע או ניסיון: איך מדביקים שני חלקי אבן (גירנית), ובאיזה חומר/ים יש להשתמש ? שני החלקים הם יחידה אחת, שנחלקה לשניים עקב מכה. תודה, בנצי (talk) 10:08, 11 June 2019 (UTC)[reply]

Please, WP:SPEAKENGLISH. Bazza (talk) 10:18, 11 June 2019 (UTC)[reply]
Please, use translate.google.com or something. It's just the same thing in (presumably) Hebrew. Wnt (talk) 15:37, 11 June 2019 (UTC)[reply]
@Wnt: I'm not sure who that comment is aimed at. WP:SPEAKENGLISH doesn't mention translate.google.com, or any other translators. The OP could have translated their second text to English (for the English Wikipedia) using such a translator first. Common courtesy, rather than expecting people you want to help you to do it for you. Google says the extra text is "The question is for those with knowledge or experience: how to glue two pieces of stone (chalk), and what material (s) should be used? The two parts are one unit, divided by two due to a blow. Thanks, Bentzi". Bazza (talk) 16:03, 11 June 2019 (UTC)[reply]

As Wnt said, Hebrew and English parts of the question are identical in meaning. For repair, I'd use a landscaping adhesive. Pick a color that matches the stone in case some adhesive squeezes out. Try to match the two parts exactly as they were before the break, and use as little adhesive as possible so it doesn't squeeze out. Dr Dima (talk) 19:44, 11 June 2019 (UTC)[reply]

Impossible to say precisely without knowing more details. In particular, how neat the result needs to be - the answer is different for a garden wall vs. a museum conservation repair.

Mostly such a repair would involve insetting a non-corroding metal dowel. This is glued into place (traditionally) with lead-based alloys (or Cerrosafe, for good work), or even molten sulphur! Modern work would use an acrylic adhesive (these are sold commercially for putting screws into stonework). You could also use an epoxy adhesive, which is what most people would think of first. Use a good epoxy though, like West System.

Really though someone, who is skilled at such repairs, needs to look at the piece. Andy Dingley (talk) 11:04, 11 June 2019 (UTC)[reply]

A very quick search turns up [9] as a top hit. Is that a stab in the right direction or do you have a different application? Wnt (talk) 15:37, 11 June 2019 (UTC)[reply]

Another important factor is what conditions it will be subjected to following the repair. If it will sit on a shelf in an air conditioned room, that's relatively easy. If it will be outside and subject to all ranges of weather, that's quite a bit trickier. SinisterLefty (talk) 20:16, 11 June 2019 (UTC)[reply]

lume mortar or orvordibary mortar I mean, wotz ur problem o?80.2.21.170 (talk) 00:08, 12 June 2019 (UTC)[reply]

Dosimetric values for sensing ionizing radiation

I have read in a blog that immediate physiological clues of ionizing radiation - smell of ozone (apparently due to ionization of air), metallic taste and eye irritation - begin at or above 10 roentgens. Are there reliable sources for this, mentioning minimal dosimetric threshold for such feelings? Thanks. 212.180.235.46 (talk) 13:55, 11 June 2019 (UTC)[reply]

Although many effects are possible, the most common immediate signs and symptoms of radiation poisoning are nausea and vomiting.

Here is Understanding Radiation, a guide for emergency first responders from Lawrence Livermore National Laboratory.

Here is Radiation Sickness from the Mayo Clinic. Again, the early signs are nausea and vomiting.

Nimur (talk) 14:54, 11 June 2019 (UTC)[reply]

I know. I'm more interested in corresponding dosimetric values, e.g. to what value do ozone smell and metallic taste correspond to? I only know that this means strong radiation. 212.180.235.46 (talk) 15:10, 11 June 2019 (UTC)[reply]

I'm not certain that there's any meaningful threshold: ozone can be produced by chemical reactions that have nothing to do with incoming radiation; and ozone can also be produced by low doses of ultraviolet radiation (which, to be fair, may qualify as "ionizing" radiation - but not always); meanwhile, arbitrarily-high incidence of certain wavelengths of ionizing radiation might produce negligible ozone. Here's a detailed, scientifically-accurate FAQ from NOAA: How is ozone formed in the atmosphere?

As far as the symptom of "metallic taste," that's also one whose correspondence to ionizing radiation is weak, at best. For example, Burning Mouth Syndrome (from Mayo Clinic) lists "metallic taste" as a common symptom. I recall reading about this symptom, because not too long ago, that exact article came up in a discussion on Wikipedia's Science Reference desk - ... about peach allergies.

After reviewing a bunch of reputable sources that I trust - things like the radiology health guides at our national labs - and finding zero discussion of user-reports of "ozone smell" and "metallic taste" associated with radiological health, I would personally conclude that these are not common symptoms. If you found a blog or other discussion, they may be repeating apocrypha that is unfounded in scientific experiment.

If a subject smells ozone, it is probable to conclude that they are being exposed to ozone, not to radiation. Any direct connection between radiation exposure and ozone is tenuous and scenario-dependent.

If a subject reports a metallic taste, that may be a sign of a different underlying condition - possibly connected in some fashion to an acute or chronic radiological exposure, and possibly not.

I don't think I can find any reason to associate those two symptoms with particular dose thresholds; and I can't find any reliable resource that makes that connection either. At low doses, a subject might not notice exposure (even if harm is being caused); at higher doses, a subject will typically experience nausea; and even if we raise the acute exposure to exceptionally dangerous levels, a subject will begin experiencing the more grisly symptoms, like rapid hair loss, diarrhea, blood-loss, and exhaustion or unconsciousness; but I cannot find reports of "tastes" and "smells."

If anything comes to my mind, it sounds like somebody's mixing up symptoms - after all, a lot of emergency and military training doctrine lumps together all the chemical and radiological safety into one set of doctrine - because whether the cause is radiological or chemical, many of the "next steps" for containment, evacuation, and treatment are exactly the same. Bad smells and bad tastes can also be an indication of exposure to lots of chemical hazards, but I do not think they are commonly associated with nuclear (or ionizing) radiation exposure.

Nimur (talk) 20:26, 11 June 2019 (UTC)[reply]

Can you link us to the blog post you referred to? Ionizing radiation can, by definition, ionize the oxygen in air, which can generate ozone; it can also produce a lovely blue glow. But as Nimur notes, this is not a guaranteed way to measure radiation, as the amount of ozone produced will depend on environment. Air is an uncontrolled mixture of chemicals which can produce a lot of different chemical reactions when energized. Also, as the article notes, the roentgen is an old unit that is generally avoided today. The roentgen itself measures air ionization, which does not have a simple relationship with things such as the amount of radiation absorbed by tissue, which is what matters for symptoms of radiation sickness. Obligatory meme: "Only 3.6 roentgen. Not great; not terrible, like a chest X-ray." --47.146.63.87 (talk) 23:46, 11 June 2019 (UTC)[reply]

June 12

Chernobyl

Hi. After watching the mini-series and reading alot of articles on WP about the disaster, I read about Valery Khodemchuk. The list states "likely killed immediately; body never found, likely buried under the wreckage of the steam separator drums". Would there be any remains left of him, or would it all be destroyed due to the radiation? Thanks. Lugnuts ^{Fire Walk with Me} 10:26, 12 June 2019 (UTC)[reply]

It's difficult to find factual information on the condition of one specific individual. Contemporaneous news stories reported in Western newspapers, like this 1986 story from the Los Angeles Times, are sparse on detail, except to say that the unrecovered remains will be left inside the building inside the protective concrete casing. The condition of the remains is unknown; it may have been exposed to ionizing radiation, fire, water, and debris.

From my archive of emergency preparedness, here are some helpful links:

Explosions and Blast Injuries - A Primer for Clinicians, from the CDC Mass Trauma Preparedness website
Bombings: Injury Patterns and Care from the American College of Emergency Physicians - a full course including two segments on radiological effects, and the handy pocket reference to injury patterns

These resources help medical responders know what to expect, and help first responders prepare for the logistical and psychosocial effects of a major nuclear incident.

From a more academic approach, here is a 1954 publication, Pathology of Total Body Irradiation in the Monkey. This is research from an era when ~~government researchers~~ private-sector individuals in Western societies conducted experiments to see what would happen if...

If you really want to know what happens to a body after it dies, you might start by reading about the methods of forensic pathology, so that you learn what normally happens; and then read onward to see what is unique to a highly-irradiated individual.

Even in a conventional disaster, human remains are not always locatable. For example, the fire near my home in 2018 killed more people than the Chernobyl nuclear incident, and there are still more persons reportedly killed whose remains were never located. They may be in unknown locations; they may be so severely damaged by trauma, fire, debris, or crushing, that they are unidentifiable.

Nimur (talk) 12:26, 12 June 2019 (UTC)[reply]

Thank you. Lugnuts ^{Fire Walk with Me} 15:09, 12 June 2019 (UTC)[reply]

Radiation could potentially preserve a body, by killing off all the bacteria that would normally decompose it (however, bacteria are resilient, so it would take a lot of radiation). That would leave dehydration/mummification as a possibility, but if enough moisture was sealed inside, that might not have happened, either. SinisterLefty (talk) 17:25, 12 June 2019 (UTC)[reply]

Ionizing radiation doesn't do much to the macroscopic structure of organic tissue. It's bad for living things because it damages or kills cells, but it won't turn a dead body into a puddle of goo (unless it manages to heat it to a quite high temperature, but for that you would need a substantial amount of radiation focused directly on the body, like what you'd get from chucking it into the path of a particle accelerator beam). Indeed, as others have noted, irradiation is actually a good way to preserve organic material, because it damages or kills the microbes that otherwise decompose it, and that's why it's used as a method of food preservation. When an unpreserved corpse decays, some of that is due to liberation of enzymes from tissues and organs, but most of it is microbes, and other decomposers such as insects and fungi, beginning to digest it. --47.146.63.87 (talk) 19:13, 12 June 2019 (UTC)[reply]

How many microohms of resistance do the circulating US coins have?

If you cleaned them to the bare, uncorroded metal and soldered square contacts the thickness of the coin to the rim, 180 degrees apart. The 1981 to 1909 penny must be pretty damn low as it's almost pure copper and not that big (19mm), is it thick and small enough to outconduct all the undebased silver coins? Sagittarian Milky Way (talk) 13:07, 12 June 2019 (UTC)[reply]

Electrical_resistivity_and_conductivity quotes the resistivity of Copper 16.78 nΩ·m (at 20 °C). It is difficult to make an accurate resistance measurement of a coin material by the means described and it is more appropriate to measure its Sheet resistance using Four-terminal sensing. Typically a constant current is applied to two probes, and the potential on the other two probes is measured with a high-impedance voltmeter. For details see Van der Pauw method. The composition of US penny coins from 1909 is copper 95%, tin/zinc 5%. Due to wartime shortages of copper the 1943 steel cent was struck in zinc plated steel that tends to rust around the edge, being the only regular-issue US coin that contains no copper and can be picked up with a magnet. DroneB (talk) 13:36, 12 June 2019 (UTC)[reply]

The Big Bang & Evolution

User was indef'd. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:54, 12 June 2019 (UTC)[reply]

The following discussion has been closed. Please do not modify it.

Has The Big Bang & Evolution been proven, If so, Why are they still addressed as theories? What I mean is that for a long period of time in history there has been debates about the origin of life & some people have held it that a supreme being or beings were responsible & some have held it that the universe naturally came into being through natural selection. There have been many scientific contradictions but there seems to be a favouring of natural selection. I can cite science articles, books & passages that speak for/against both sides to prove that I am not giving my own personal opinions & biases but looking & presenting the implications objectively. This is a discussion that should be had because if anything in life is sacred, the truth is...A true scientists should look at the implications objectively,be prepared to be proven wrong & be willing to accept it. Again I will stress that I am not giving any of my own personal opinions or biases but instead, offering to present evidence while also willing to accept the possibility of being proven wrong. I have no intention of deceiving, misleading or manipulating anyone which is why I will only present & address without being personally involved. I only ask that my debate opponents (no disrespect) who may be skeptics do the same because you have every right to expect the same from me. — Preceding unsigned comment added by Repent.The End is Near (talk • contribs) 14:21, 12 June 2019 (UTC)[reply]

"Proof" has many different, but related meanings. In the strict mathematical/logical sense, nothing about the real world can ever been proven - it's always possible that you are kept imprisoned by an evil demon that just feeds your brain inputs that simulate a particular sense of reality. In that sense, science never "proves" anything. A scientific theory is a coherent body of knowledge describing aspects of reality, and allowing us to make predictions. If such a theory agrees with observations and if more and more of its predictions come true, we eventually consider it "provisionally true". This provisional truth of science is a much stronger level of truth than e.g. that accepted by most legal systems even in criminal cases. In this sense, evolution is both an observed fact and a proven theory (i.e. we can observe actual live evolution as well as past instances of evolution, and the theory of evolution describes how these observed instances of evolution come about). The Big Bang is a (putative) event (and quite independent of the theory of evolution) that is largely compatible with and explained by the general theory of relativity. I would say evidence for the event is a bit more tentative than for evolution, but as a theory it has a huge amount of observational support - e.g. the cosmic microwave background. Both evolution and the Big Bang have vastly more supporting evidence than any competing theory, and neither has any unsurmountable difficulties, which is why they (or some more specific versions of them) have nearly universal support by scientists. --Stephan Schulz (talk) 14:52, 12 June 2019 (UTC)[reply]

For the most part, true scientists DO look at the implications objectively and are prepared to be proven wrong and be willing to accept it. It's religionists who are generally unwilling to do likewise. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:04, 12 June 2019 (UTC)[reply]

I agree with Baseball Bugs. What you are asking here for scientists to do is something that they regularly do, but in my experience is very rare when it comes to those who reject the Big Bang and evolution. Gnome de plume (talk) 15:49, 12 June 2019 (UTC)[reply]

The user is a crusader, and crusaders don't last long on Wikipedia. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:50, 12 June 2019 (UTC)[reply]

They are certainly welcome to have a civil discussion here with people like you and me though. Gnome de plume (talk) 15:53, 12 June 2019 (UTC)[reply]

Follow their "contributions" for more insight. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:55, 12 June 2019 (UTC)[reply]

"true scientist" are hard to distinguish beforehand. I even dare say there is science, that is, a way to properly do scientific work, but there are NO scientists. Remember that Newton, just like pretty much EVERY great scientist, was also a firm believer in very nutty ideas & disbeliever of very solid evidence (as we can see in retrospect; easier for us, dwarfs on giants shoulders). Richard Feynman lectures include the statement "Science is the belief in the ignorance of experts." (and by expert he meant scientists just as well). Just never trust anyone who says you must trust science and scientist, because, he is bullshitting you. Trust their achievement, trust the mechanics you see working, but don't them as "scientists" nor trust their holy scripture: this is just the very opposite of science. Gem fr (talk) 16:23, 12 June 2019 (UTC)[reply]

Agreeing with all of the above, I would had that we trust theories insofar as they allow practical operation like, building objects, or, sailing west to reach far east place (this wont work on a flat Earth, only on a round/cylindrical one).

Evolution theory, and all its modern development, include feat like genetically modified organisms. These exist and work. This is no proof that the theory is right, but this is enough of a confirmation to stick with it, and the theory just has no real problem to justify searching for alternatives (problem of the kind physics was struggling with, before Einstein papers).

Big bang is just a mathematical development of the framework underlying general theory of relativity. We DO have lots of practical objects also relying on this theory (for instance, it is needed to synchronize clock on earth and clock on-board satellites, those having enough acceleration to produce time dilatation that must be reckoned with. There exist however legit alternatives to general relativity (see article for reason why). Gem fr (talk) 16:06, 12 June 2019 (UTC)[reply]

I just realize we must have tons of archived answers about this question. I regret my previous answer Gem fr (talk) 16:58, 12 June 2019 (UTC)[reply]

bingo. "evolution theory proof" turns 448 results in refdesk archive. same for "big bang proof": 282. Methink we should just delete the question. Gem fr (talk) 17:04, 12 June 2019 (UTC)[reply]

No, that would mean you should include links so the OP can find them, not delete the Q. SinisterLefty (talk) 17:10, 12 June 2019 (UTC)[reply]

As for evolution, there's no credible evidence that the theory is completely wrong, but there is room for some "tweaks". One somewhat recent tweak is that it seems evolution is not steady, but occurs in jumps and starts, spurred on by forces like a change in the environment, such as an ice age or competition with an introduced species (especially humans). An even more recent tweak is that it seems that some of our genes change over our lifetime, and are passed down, much as Lamark proposed, in an earlier version of evolution theory. See transgenerational epigenetic inheritance. The Biblical account of the creation of the universe and species, on the other hand, has massive proof against it, from fields as diverse as zoology, botany, biology, chemistry, geology, astrology, physics, archaeology, anthropology, linguistics, etc. The only way to make creationism compatible with science is to say that God(s) created the Big Bang and then just watched what happened. This is the Watchmaker analogy, but has nothing to do with what the Bible or other holy books say happened. SinisterLefty (talk) 17:10, 12 June 2019 (UTC)[reply]

Lots of creationists have just zero problem conciliating Biblical account of the creation of the universe and species with evidence Gem fr (talk) 19:34, 12 June 2019 (UTC)[reply]

Where religionism fails is that they start with the assumption that their scriptures are true, and anything that disagrees with that assumption must be ignored - or, if they're really desperate, declare that any evidence that contradicts their scriptural beliefs is "the work of the devil." As one of my old math professors liked to say, "If you start with invalid assumptions, you're liable to get 'interesting' results." ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:24, 12 June 2019 (UTC)[reply]

Yes, science is about following the evidence, wherever it leads, while religion is about cherry-picking only the evidence which supports your beliefs. SinisterLefty (talk) 17:28, 12 June 2019 (UTC)[reply]

To be fair, lots of the "science" is ALSO about cherry-picking only the "evidence" which supports your beliefs. For instance, Marcellin Berthelot considered the atomic hypothesis superfluous, and, hence, to be rejected under Occam's razor; while this hypothesis was already more consistent with evidences, having doubt about it was still legit. At the opposite spectrum, string theory has believers, without any evidence it being necessary and quite a number of unsolved problems. Gem fr (talk) 19:00, 12 June 2019 (UTC)[reply]

To be fair, science and religion to not cherry-pick. People do. While there are scientists who cherry-pick, and are heavily discredited for doing so, there are far more religious people who cherry-pick, and are considered more faithful for doing so. 68.115.219.130 (talk) 19:12, 12 June 2019 (UTC)[reply]

Being scientist Vs being religious is not between people, it is inside each an every people. People who call themselves scientist are often acting as member of sect to defend the faith in their science (which may or may not be supported by evidence Gem fr (talk) 19:34, 12 June 2019 (UTC)[reply]

Science is not in any way based on faith. If you believe so, you are not referring to science. You are referring to pseudoscience - such as astrology and homeopathy. 68.115.219.130 (talk) 19:42, 12 June 2019 (UTC)[reply]

Well, not exactly. Science requires the faith that we can trust our senses and our instruments to make observations. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:29, 12 June 2019 (UTC)[reply]

I smelled this rat. Don't we have some kind of (polite; more polite that I would be...) RTFM, to redirect questions about relativity, evolution etc. to refdesk archive, where they were asked hundreds of time? Gem fr (talk) 22:24, 12 June 2019 (UTC)[reply]

It's been suggested from time to time that the ref desk should have a "frequently asked questions" page, with maybe something easier to navigate than the actual archives. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:28, 12 June 2019 (UTC)[reply]

Bond survivability

In a James Bond novel (title in rot13: Zbbaenxre) Bond flees from the villain through steam pipes and survives by huddling inside them while the villain blasts hot steam (not convinced that Bond is in the pipes, but as a precaution). He's badly burned, but escapes and recovers in full in a hospital. Contrary to the movies, it seems to me that Fleming at least paid lip service to realism in the books, but surviving something like this still seems like a little over the top, considering how uncomfortable is even a waft of mere 100°C steam from a coffee pot. Are the any real chances of someone surviving an (I think) 30-second blast stuck to the sides of a (presumably hot) metal pipe, and being well enough to crawl off afterwards? 93.136.9.45 (talk) 23:15, 12 June 2019 (UTC)[reply]