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Surprising Discovery Hints Sonic Waves Carry Mass (scientificamerican.com)
jbmartin6 shares a report from Scientific American: In a paper published in Physical Review Letters, a group of scientists has theorized that sound waves possess mass, meaning sounds would be directly affected by gravity. They suggest phonons, particle-like collective excitations responsible for transporting sound waves across a medium, might exhibit a tiny amount of mass in a gravitational field. "You would expect classical physics results like this one to have been known for a long time by now," says Angelo Esposito from Columbia University, the lead author on the paper. "It's something we stumbled upon almost by chance."
Esposito and his colleagues built on a previous paper published last year, in which Alberto Nicolis of Columbia and Riccardo Penco from Carnegie Mellon University first suggested phonons could have mass in a superfluid. The latest study, however, shows this effect should hold true for other materials, too, including regular liquids and solids, and even air itself. And although the amount of mass carried by the phonons is expected to be tiny -- comparable with a hydrogen atom, about 10^-24 grams -- it may actually be measurable. Except, if you were to measure it, you would find something deeply counterintuitive: The mass of the phonons would be negative, meaning they would fall "up." Over time their trajectory would gradually move away from a gravitational source such as Earth. "If their gravitational mass was positive, they would fall downward," Penco says. "Because their gravitational mass is negative, phonons fall upwards." And the amount they would "fall" is equally small, varying depending on the medium the phonon is traveling through. In water, where sound moves at 1.5 kilometers per second, the negative mass of the phonon would cause it to drift at about 1 degree per second. But this corresponds to a change of 1 degree over 15 kilometers, which would be exceedingly difficult to measure.
Esposito and his colleagues built on a previous paper published last year, in which Alberto Nicolis of Columbia and Riccardo Penco from Carnegie Mellon University first suggested phonons could have mass in a superfluid. The latest study, however, shows this effect should hold true for other materials, too, including regular liquids and solids, and even air itself. And although the amount of mass carried by the phonons is expected to be tiny -- comparable with a hydrogen atom, about 10^-24 grams -- it may actually be measurable. Except, if you were to measure it, you would find something deeply counterintuitive: The mass of the phonons would be negative, meaning they would fall "up." Over time their trajectory would gradually move away from a gravitational source such as Earth. "If their gravitational mass was positive, they would fall downward," Penco says. "Because their gravitational mass is negative, phonons fall upwards." And the amount they would "fall" is equally small, varying depending on the medium the phonon is traveling through. In water, where sound moves at 1.5 kilometers per second, the negative mass of the phonon would cause it to drift at about 1 degree per second. But this corresponds to a change of 1 degree over 15 kilometers, which would be exceedingly difficult to measure.
If it turns out that sound has a negative amount of mass, does this fix many of the problems with dark matter and the weight of the universe? Is dark matter just ... sounds?
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Sound travels through matter, so consists of, well, "phonons" that are really just the slightly altered movements of the matter the sound travels through. Sound exists for as long as that extra movement exists, and for it to exist, the matter needs to be excited, ie possess energy, over and above ambient. So that means sound waves traveling perpendicular to a gravity field have a tendency to be a little less affected by that field than ambient matter. So it looks like phonons have negative mass.
So this apparent mass is an artifact of the way you look at it.
Says I, who is so very much not a physicist. Nor a patent examiner.
Wouldn't this then imply that sound should be able to pass, at least in part, through a vacuum? If sound itself has mass, then sound itself isn't a vacuum...
... like someone got his fundamentals mixed up. I'm sure mass in motion (sound) is hampered/influenced by gravity as it should, but that doesn't mean it itself has mass. I expect this guy's findings to be dismissed any time soon
We suffer more in our imagination than in reality. - Seneca
Given the idiocies all the other commenters wrote at this point, including TFS, you're the only one here who hit the nail on the head.
It seems people don't get that infomation is not a physical object (matter/energy) itself, but only the *structure* of matter/energy. So it's a meta level. In a medium. With different meta laws.
Hence the whole "intellectual property" oxymoron confusion.
TL;DR: Sound does not have mass. The particles that form the medium of sound, do.
Sound is a meta level, so it can only have meta mass. Its "mass" isn't real, just as phonons aren't real. They are only a useful construct.
Let's say you grab the end of a cable tied down at the other end, and you give it a thwap - send a pulse down that chord, that bounces as it hits the end, reducing much like a sound wave. No sound, but a propagating wave in a physical medium that can also make sound if you plucked it instead of whipping it.
Does that add mass?
If so, is there anything special about sound in this? Or would any chain reaction propagation of kinetic energy do the same?
The actual article seems to emphasize that the wave is more 'carrying' mass, rather than establishing any that wouldn't exist anyway - so really, this seems more a matter of measurement and classification of where mass is at any moment, rather than new atoms springing into existence or something.
There's no special detectable radiation from sound in our environment - just, you know, the kinetic wave we're used to.
Ryan Fenton
I'm having trouble with the concept of negative mass, too. The phonons would not just move away from the earth, but also from the sun, from the center of the galaxy, etc... Where do you stop? And would they also move opposite to other mass in the accelerating expansion of the universe? Relative to what center?
It also seems quite difficult to reconcile this with General Relativity where, for example, you are not supposed to be able to tell whether an elevator is in a field of gravity or accelerating without gravity. Both situations ought to be equivalent (apart from tidal forces), but clearly result in opposite accelerations when negative mass is involved.
Come on now. Science is not limited to the domain of experimental science.
Science broadly construed is the search for hypotheses that unite various phenomena. Experimental science merely attempts to falsify these hypotheses.
If anything, experimental science is the ugly stepsister here ...
Everything is affected by gravity including light and other massless particles. That is how they first proved relativity.
What is surprising here?
And a sound wave is a movement in particles with mass, so I think relativity also says something about changing their mass.
The problem is you have a mass of separate forces. Each force needs a binding particle to connect it to other forces, so you have a model full of mediating particles, including this phonon. Quasi particles to connect things together that somehow magically interact via force X and Y but not Z, and other particles connects Y and Z but not X....
These are not real particles, they're simply mechanisms to describe an unknown set of properties at a pinch point.
If you think of the EM Drive, it likely oscillates the electric field (directly), as each oscillation in matter is trying to stay in resonance, it might shift that field so the resonance point shifts each time creating a force. That would be an example of magnetic shifting the electric oscillation.
If you think of this sonic experiment, its likely doing exactly the same thing, but by moving oscillating matter which in turn is shifting that F oscillation field because it's moving matter that is in turn contributing to the field.
Both are likely doing the same things. Twiddling with F.
"sound can travel through what we normally think of as "vacuum", since true vacuum doesn't actually exist."
It certainly does exist. My [sandbox] model is a true vacuum, a perfect empty model with a perfect oscillating F field I use to clean up mess and play with simulated particles in isolation. Think about this sound 'speaker', it's moving matter which in turn is electric oscillating, so its adding an oscillating to the electric oscillating component. That electric oscillation CAN pass through a perfect vacuum, (it does in sandbox!).
If you recall the way I propose to change F, in my hypothetical time machine, is by a low (near zero) electric oscillation, decouple with distance, then shift that whole mechanism (the electric system and the sample) with another electric oscillation near zero. Decouple with distance, another small shift, decouple.... and on and on...
Simplified, you put in energy enough to move something W/1000 per local oscillation, i.e. 1000ths the speed of light, and you tune your frequency to local F/1000 ... does it really matter if you tweak that oscillation with electric, magnetic or even by moving plates mechanically.
If velocity is motion over an oscillating electric field, shifting the oscillation field affects velocity.
You already observed the oscillations (e.g. in electrons)
You already know everything, even neutrons have electric field.
Ergo there is an oscillating electric field everywhere.
So light must be moving over that because electro magnetic properties are all it has.
And since matter converts to light, so must matter be moving over the very same field.
Next they'll be saying that it's the trees swaying back and forth that causes wind to blow.
ðY
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Measuring the speed of the wave is indeed trivial.
Where is the relevance to the stated problem.
sudo ergo sum
Dude, Phys. Rev. Lett. is quite substantial. Physicist here.
this was a suprise to them?
Helium balloons don't have negative mass, they still have weight and are attracted by the earth. It's the heavier surrounding air that pushes the balloon up (pressure gradient provides more force than gravity).
So you're saying that phonon traveling through some medium (like air) is pushed up by the rest of the medium? That's not really "negative mass", just "less mass than the surrounding medium".
Not real mass.
Because phonons aren't real elementary particles. They are artifacts of the structure of real elementary particles that make up the medium.
It's a nice useful construct, but don't confuse information meta-space with real space.
And we have a winner. And if you calculate the mass of the medium out, then waves of lower density which temporarily thins the medium, will carry a negative mass if perceives as particles.
Gravity affects things differently during acceleration/deceleration - like every fringe science experiment suggests.
and it should be a constant, i agree
I'd expect that sound waves spread out a lot due do diffraction, so determining its central/average direction would be harder. It would be like measuring the vertical tilt of a tree by looking at the outline of branches and leaves. Conversely, light (from a laser) won't spread out that much over 15 km, though still noticeable amounts.
Escher was the first MC and Giger invented the HR department.
I'm having trouble with the concept of negative mass, too. The phonons would not just move away from the earth, but also from the sun, from the center of the galaxy, etc... Where do you stop? And would they also move opposite to other mass in the accelerating expansion of the universe? Relative to what center?
I'm having trouble with the concept of positive mass, too. The phonons would not just move towards the earth, but also towards the sun, toward the center of the galaxy, etc... Where do you stop? And would they also move opposite to negative mass in the accelerating expansion of the universe? Relative to what center?
"The legitimate powers of government extend only to such acts as are injurious to others." Thomas Jefferson.
In water, where sound moves at 1.5 kilometers per second, the negative mass of the phonon would cause it to drift at about 1 degree per second. But this corresponds to a change of 1 degree over 15 kilometers, which would be exceedingly difficult to measure
Uh, if sound moves at 1.5 km/s, and drifts by 1 degree/s, then in 1 second it should have drifted by 1 degree and travelled 1.5 km, not 15km? After 10 seconds it will have travelled 15 km and drifted by 10 degrees, which surely would be measurable. (PS: I read the article, the summary quotes the article correctly.)
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Call proc signature()
I'm having trouble with the concept of negative mass, too. The phonons would not just move away from the earth, but also from the sun, from the center of the galaxy, etc... Where do you stop?
I'm having trouble with the concept of positive mass, too. The phonons would not just move towards the earth, but also towards the sun, toward the center of the galaxy, etc... Where do you stop?
For positive mass this is no problem. The earth is attracted to the sun, and so is everything on earth, so the relative acceleration between objects on earth and the earth due to the gravity of the sun is zero (apart from small tidal forces). Same for the center of the galaxy which attracts the sun, the earth, and everything on earth. This is unnoticeable because the whole system gets the same acceleration towards the center of the galaxy. And the same goes for whatever acceleration we get from the acceleration of the universe. Whatever the cause of this acceleration (dark energy,...), it acts the same on all mass so it doesn't cause local relative accelerations.
For negative mass, though, all these forces do become important. If we are attracted by the sun, and something here on earth is repelled by the sun, it appears to get a double acceleration away from the sun relative to us. And for the expansion of the universe, which gives an acceleration proportional to distance, we don't even have a reference point so the calculation becomes nonsensical.
Also, take Einstein's famous elevator example to demonstrate the equivalence between gravity and acceleration. Take an elevator in outer space far away from any gravitational influence. The elevator contains a positive and a negative mass, both floating somewhere in the middle. Accelerate the elevator "upward" and both masses will appear to fall down. Now take the same elevator and place it on the surface of the earth. Now the positive mass falls down while the negative mass goes up. Ergo, contrary to one of the most basic assumptions of General Relativity, gravity is not equivalent to acceleration. So, GR goes out the window?
If you understood classical physics, you'd understand that there is no difference between the statements. The wind cannot push the tree without the tree swaying. The tree cannot sway without pulling the wind. Pulling and pushing are identical; we call one an "action" and the other a "reaction" because it is easier for humaans to understand, but they're not separate; you can't have only one, which would be required for it to be causal.
This has been understood by Metallica for a long time now.
I mean, why do you think they call them "Heavy Metal" bands?
CAP === 'contempt'
In how far can this be deducted from 'classical' physics? Because phonons are not real, but quasiparticles, only quantised because of the geometrical setup.
Meaning: sonic waves have differences in pressure in them. Something of low pressure tends to go up (helium balloons) in a material, and vice versa.
What if these do not eliminate each other exactly within one wavelength?
It doesn't explain dark matter. But I'm sure this is somehow related to Superman's ability to fly.
I'll bet if you applied lorentz and electrostatic forces to the equations, you'd find the rapidly-changing velocities of air particles do allow for particles to be moved in this manner. The effect should increase severalfold when the entire apparatus is surrounded in a larger static magnetic field.
If there is a 1 degree per 15 mile rise in sound underwater, I would imagine that the Navy would have some evidence of it already, due to the use of sonar. I'm pretty sure they would notice a systematic error in position like that. Now whether they recognized it as an artifact of negative mass who knows, but they should have data that shows the deflection.
I'm quite sure that the geniuses at Monster Cable have already patented some gravity cancelling cables with gold plated connectors, which will allow the sound to reach your ears at the proper angle.
Wouldn't this then imply that sound should be able to pass, at least in part, through a vacuum?
No. By definition sound cannot pass through a vacuum. Oversimplifying here but sound is defined as a pressure wave through a medium. No medium = no sound.
If sound itself has mass, then sound itself isn't a vacuum..
Probably an imprecise statement. It's not that sound has mass so much as that it carries energy which has an effect on mass of the medium through which it travels. I've never really thought about it explicitly but it makes some sense that sound and mass would have some relationship. (E=mc^2 and all that)
If you get into the weeds of it, mass doesn't actually mean what your intuition probably tells you. Particles don't actually have a mass that is a single value. What we think of as mass is really just the expected value but at any given time it can vary according to a probability distribution. Also there is the fact that if you add up the weight of the particles in a molecule it's common for the weight of the molecule to be different from the weight of it's constituent particles. Energy into our out of a system can often affect mass in some subtle and not so subtle ways.
Yes. It seems many readers skipped "particle-like collective excitations" in the summary.
Theory is a part of the process. It is not enough by itself to be "science", being only the first step in the scientific method. Or, put differently, theory that never gets tested never becomes science.
Theory alone is just story telling within a rigorous framework, and the vast majority of published theoretical work is eventually disproven. Heck, there have been 20ish years of published theory about "inflation", and there will likely be decades more, thousands upon thousands of speculations. At most one is right.
And don't get me started on string theory.
Socialism: a lie told by totalitarians and believed by fools.
"The Alcubierre drive is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by Mexican theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created."
https://en.wikipedia.org/wiki/Alcubierre_drive
"Thus, in a very physical sense, the phonon carries (negative) mass."
https://arxiv.org/pdf/1807.08771.pdf
Big apple, new Yorik, undig it, something's unrotting in Edenmark.
Anything that stores energy has mass doesn't it? So a sound wave which is a melange of oscillations of kinetic and potential energy has mass. So this is already known.
Additionally, if it's like a photon, then it is not going to have any additional mass on top of that I believe though I might be wrong.
Some drink at the fountain of knowledge. Others just gargle.
oops... accidentally deleted half my post when I submitted it.
Anyhow, so how do we get to negative mass? I think there are two ways that are essentially realted.
in a nutshell, this is like an airbubble in water. The air bubble is made of air so it has mass. But it floats up like it has negative mass.
Consider the mass defect effect. That's the reason why isoptopes weigh less than they should. the reason is that the attractiv forces in the nucleous create abinding energy well the neutrons are in. So they have less not more energy than a free neutron. As a result they also have less mass than a free neurtron.
If you were to imagine (incorrectly but a sufficient picture) a neutron as oscillating electrons and protons (or quarks), and you would describe what you saw as much like a sound field or a pendulum in which energy flowed back and forth from potential to kinetic energy in the oscillations. And so you would say hey, those oscillations seem to be creating negative mass. But that's backwards. What's happening is the binding forced are what cause the oscillation ust as gravity causes a pendulum. So the binding field has created a lower mass for the particle like the mass defect.
THe other way is to analogize this to the "holes" in semiconductors. We often refer to the "holes" (missing electrons) as having a mass. THey don't but if you model then that way they act like they do. In reality, in a classical picture, they are just missing electrons in a sea of electons. But when we switch to quantum model they become particles and we give them a mass. But this is just subtracting a constant surrounding mass whose inertia is what makes the holes appear to have inertia. If you ejected a hole into free space it would not even exist!
thus you get negative mass when you are subtracting a background.
Some drink at the fountain of knowledge. Others just gargle.
Sonic waves carry energy. Energy is mass. We've known this for about a century.
But negative mass (according to TFA). And so negative energy.
Have gnu, will travel.
My sound waves do travel up. That's why I have to talk down to people.
Also, I would be more surprised if quasiparticles *didn't* have mass associated with them - would be a violation of matter energy conservation. With inelastic scattering you can map out phonon energy distribution as well. Not belittling any of their work, always neat to see things confirmed experimentally.
Disregard comment below - went full /.'er and just skimmed the summary. Missed "negative" mass - now I can safely say I don't understand the results at all.
I'm having trouble with the concept of negative mass, too. The phonons would not just move away from the earth, but also from the sun, from the center of the galaxy, etc... Where do you stop?
You don't have to stop. The force due to gravity is F=GMm/r^2. Make the little m negative, it becomes a repulsive force inversely proportional to the square of the distance (instead of the attractive force for positive mass).
It also seems quite difficult to reconcile this with General Relativity where, for example, you are not supposed to be able to tell whether an elevator is in a field of gravity or accelerating without gravity. Both situations ought to be equivalent (apart from tidal forces), but clearly result in opposite accelerations when negative mass is involved.
Not if the inertial mass and gravitational mass are both negative. If they are, then F=ma means acceleration is opposite the applied force, which while weird still gives equivalence between gravitational and inertial mass.
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
But if the gravitational force is repulsive and the acceleration is also opposite to the force, they would fall down rather than up, wouldn't they?
The particles are moved from additional energy, is this the mass? Are they treating the transfer of this from particle to particle as some kind of virtual particle?
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Does that mean that the noisier the plane engines the better the plane flies? :P
Witches should fly on vacuum cleaners, not brooms.
You get the idea.
"Everybody's naked underneath" -- The Doctor
The rest mass of an electron is pretty much a single value... in fact it's a fundamental constant you could say.
Not what I'm talking about. PBS Space Time has a very good video which explains what I'm talking about far more eloquently than I probably could. Totally worth watching.
Sorry, but this is plausible. It would need careful calculation, but it's plausible. My reasoning is thus:
Sound (in air) originates as a wave of compression, which squeezes things away from it, followed by a wave of de-compression, which allows things to return. If the sound encounters a barrier (necessary to create a phonon), then the pressurization still squeezes molecules out, but the barrier prevents easy return, so the mass of the air within the phonon will be less than the mass of the air away from the sound wave, and therefore it will be pulled less strongly towards the closest gravitational source.
So. Plausible "negative mass" within the phonon when contrasted with external to the phonon. Not an absolute negative mass, but a relative negative mass caused by a lesser average density.
That said, I'm not sure how to translate this into waves moving through an incompressible medium, but it's been a long time since I took physics, and acoustics got only minor coverage when I took it.
I think we've pushed this "anyone can grow up to be president" thing too far.
the ratio of the sines of the angles of incidence and refraction of a wave are constant when it passes between two given media.
So basically the sound kind of bounces off the pressure gradient caused by gravity, lifting the mass of the medium with it (slightly). The authors themselves discuss how it is equivalent to sourcing gravity, how to measure the effect in the conclusion, and mention how the same effect could cause two parallel sound save packets to experience a very slight attractive force.
Ultimately we knew to start with these assumptions because positive gravity obviously does work and we achieve at least some form of localized stability for a reasonable measure of time. Either the same be assumed of negative mass or we can assume it is so unstable as to not impact the stability of other systems or it may well be that it has been a factor all along and we've accounted for it with constants or other small adjustments in the formulas across many other measurements causing them to give functional results but for logically incorrect reasons.
.
Is about 250 meters, following the 1:60 rule used in navigation. I would've thought a 250m offset is large enough to measure, but maybe not with sound in water.
Force = mass x acceleration. If the force of gravity is negative, and mass is negative, acceleration is positive. So negative mass stuff would still fall down, right?
(I have read quite a few classical physics books, and a few about special and general relativity as well)
Does this mean you could theoretically vibrate an object out of orbit? The article suggests the effect could change the ticking of an atomic clock, so this effect apparently isn’t just imaginary for the phonons themselves. I’m assuming this effect is only gravitational and not inertial? Any actual physicists around who can speak to this?
No matter how many people lean to the west, they will not cause a west wind to blow. They'll just fall over and feel silly.
Don't confuse an immediate local interaction with causality.
"In water, where sound moves at 1.5 kilometers per second, the negative mass of the phonon would cause it to drift at about 1 degree per second. But this corresponds to a change of 1 degree over 15 kilometers, which would be exceedingly difficult to measure."
Wow....it would also correspond to a change of 1 degree over 1 millimetre. And a change of 1 degree over 1 billion parsecs.
The rest of this pathetic post is similarly utter ignorant nonsense babble from someone who doesn't understand the most basic concepts.
For the correct delivery of phonons to your eardrums, use Siltech Royal Signature Emperor Double Crown Loudspeaker cables. The have elegant self-shielding topology.
When they came for the communists, I said "He's next door. Take him away. Goddam commies."
How's life in the hypocrite lane?
So basically they just move opposite to the pressure gradient of the gas. Makes sense, negative mass is BS to get headlines.
You should stop worrying about big-picture stuff like 'science' and instead concentrate on reading comprehension.
In response to dude who said that theoretical physics is not science, I said science is both the positing and the empirical testing of hypotheses.
"The Alcubierre drive is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by Mexican theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created."
https://en.wikipedia.org/wiki/Alcubierre_drive
"Thus, in a very physical sense, the phonon carries (negative) mass."
https://arxiv.org/pdf/1807.08771.pdf
Big apple, new Yorik, undig it, something's unrotting in Edenmark.
You seem to have entirely missed the point what you quoted; the subject of what you quoted is not even physics. In the quote, "west wind" and "leaning" are not contextually connected. Whereas, what you replied to was referring to Newton's 3rd Law, which narrowly covers interactions between things.
And that said, yes, when you lean to the west, you do blow some wind that way.
But regardless, Newton's 3rd Law prevents cause and effect from having meaning when it comes to the action and reaction. Forces act equally due to the interaction. When you sway, and wind blows, the implication that you are swaying, and that is causing the wind to blow that is not true from a physics perspective. Perhaps it is true behaviorally, but physically it makes just as much sense to say that it was the wind pulling you over into a bend.
Interactions are guaranteed to be balanced, causality requires temporal separation and some sort of local imbalance.
Causality would be, the wind blew the tree (or the identical statement: the tree swayed in the wind) and then the tree fell down. Notice the temporal separation? Anything causal has to be over a temporal range, it can't be momentary. Whereas, the interaction between the wind and the tree is always in balance, there is no temporal component to those forces being balanced. Pushing and pulling describe the exact same thing.
This is with just two variables; in electronics it gets worse because you deal with Ohm's Law a lot, which instead of having 2 things in balance, you have 3 variables that you can measure, but that represent a single inseparable phenomena. If you think voltage and current are separate things, good luck getting transient spikes out of your circuits.
I didn't quote anything. My words were my own. You seem to have not understood them.