Researchers Find Source of Strange ‘Negative’ Gravity

Sound has negative mass, and all around you it’s drifting up, up and away — albeit very slowly.

more…

Thunder drifts upwards in all directions.

Tau.Neutrino said:

Researchers Find Source of Strange ‘Negative’ Gravity

Sound has negative mass, and all around you it’s drifting up, up and away — albeit very slowly.

more…

A seriously interesting speculation. I like it. I can’t see any obvious reason why phonons must have zero mass. They are not like photons that must have zero mass because they travel at the speed of light.

“The effect is too tiny to measure with existing technology, the researchers wrote in the new paper, which has not been peer-reviewed.”

How tiny?

“To understand how this might work, imagine a normal fluid in which gravity acts downward. Fluid particles will compress the particles below it, so that it’s slightly denser lower down. Physicists already know that sound typically moves faster through denser media than through less-dense media — so the speed of sound above a phonon will be slower than the speed of sound through the slightly denser particles below it. That causes the phonon to “deflect” upward.”

Oh, that’s just refraction. Like the bending of light upward in a mirage.

The dietary practices of the BAPS Swaminarayan Hindus is completely batshit crazy. They are strict vegetarians – no issue; but, but, but, they are not allowed to use onion or garlic. How fucked up is that!

sibeen said:

The dietary practices of the BAPS Swaminarayan Hindus is completely batshit crazy. They are strict vegetarians – no issue; but, but, but, they are not allowed to use onion or garlic. How fucked up is that!

and what has this to do with negative gravity?

roughbarked said:

sibeen said:

The dietary practices of the BAPS Swaminarayan Hindus is completely batshit crazy. They are strict vegetarians – no issue; but, but, but, they are not allowed to use onion or garlic. How fucked up is that!

and what has this to do with negative gravity?

I have no doubt that a strict vegetarian diet with no onions or garlic will significantly reduce the average mass of those who partake in this diet.

mollwollfumble said:

Tau.Neutrino said:

Researchers Find Source of Strange ‘Negative’ Gravity

Sound has negative mass, and all around you it’s drifting up, up and away — albeit very slowly.

more…

A seriously interesting speculation. I like it. I can’t see any obvious reason why phonons must have zero mass. They are not like photons that must have zero mass because they travel at the speed of light.

You did?

I strongly disliked it.

To refer to this effect as “strange negative gravity” is just silly.

The Rev Dodgson said:

roughbarked said:

sibeen said:

The dietary practices of the BAPS Swaminarayan Hindus is completely batshit crazy. They are strict vegetarians – no issue; but, but, but, they are not allowed to use onion or garlic. How fucked up is that!

and what has this to do with negative gravity?

I have no doubt that a strict vegetarian diet with no onions or garlic will significantly reduce the average mass of those who partake in this diet.

lean and mean?

The Rev Dodgson said:

To refer to this effect as “strange negative gravity” is just silly.

Yes.

JudgeMental said:

The Rev Dodgson said:

To refer to this effect as “strange negative gravity” is just silly.

Yes.

Wallowing for a better description?

I thought this thread was about the now 13 yr old I have in my house…

Arts said:

I thought this thread was about the now 13 yr old I have in my house…

That situation certainly has gravity.

roughbarked said:

Arts said:

I thought this thread was about the now 13 yr old I have in my house…

That situation certainly has gravity.

Teenager years with girls are the best, I’m looking forward to doing it again in just under a years time

Cymek said:

roughbarked said:

Arts said:

I thought this thread was about the now 13 yr old I have in my house…

That situation certainly has gravity.

Teenager years with girls are the best, I’m looking forward to doing it again in just under a years time

you’re a nice guy, but completely off your rocker

Arts said:

Cymek said:

roughbarked said:

That situation certainly has gravity.

Teenager years with girls are the best, I’m looking forward to doing it again in just under a years time

you’re a nice guy, but completely off your rocker

I was one, I would not want to parent one.

Two male teens was dreadful, sometimes.

The Rev Dodgson said:

mollwollfumble said:

Tau.Neutrino said:

Researchers Find Source of Strange ‘Negative’ Gravity

Sound has negative mass, and all around you it’s drifting up, up and away — albeit very slowly.

more…

A seriously interesting speculation. I like it. I can’t see any obvious reason why phonons must have zero mass. They are not like photons that must have zero mass because they travel at the speed of light.

You did?

I strongly disliked it.

To refer to this effect as “strange negative gravity” is just silly.

Yes. I like anything new that isn’t obviously impossible.
Of course. You’re more practical than I am.
Agree, the reporter has hyped it.

If it’s just refraction then it’s the upwards curvature of sound waves that we see all the time in seismic studies.

But I haven’t read the arXiv paper yet.

mollwollfumble said:

The Rev Dodgson said:

mollwollfumble said:

A seriously interesting speculation. I like it. I can’t see any obvious reason why phonons must have zero mass. They are not like photons that must have zero mass because they travel at the speed of light.

You did?

I strongly disliked it.

To refer to this effect as “strange negative gravity” is just silly.

Yes. I like anything new that isn’t obviously impossible.
Of course. You’re more practical than I am.
Agree, the reporter has hyped it.

If it’s just refraction then it’s the upwards curvature of sound waves that we see all the time in seismic studies.

But I haven’t read the arXiv paper yet.

Sexing up science is annoying as is fluff science that’s high on showpersonship and low on information

mollwollfumble said:

The Rev Dodgson said:

mollwollfumble said:

A seriously interesting speculation. I like it. I can’t see any obvious reason why phonons must have zero mass. They are not like photons that must have zero mass because they travel at the speed of light.

You did?

I strongly disliked it.

To refer to this effect as “strange negative gravity” is just silly.

Yes. I like anything new that isn’t obviously impossible.
Of course. You’re more practical than I am.
Agree, the reporter has hyped it.

If it’s just refraction then it’s the upwards curvature of sound waves that we see all the time in seismic studies.

But I haven’t read the arXiv paper yet.

http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/refrac.html

mollwollfumble said:

Yes. I like anything new that isn’t obviously impossible.
Of course. You’re more practical than I am.

Yes.

I don’t even think there’s anything weird about quantum mechanics.

The Rev Dodgson said:

mollwollfumble said:

Yes. I like anything new that isn’t obviously impossible.
Of course. You’re more practical than I am.

Yes.

I don’t even think there’s anything weird about quantum mechanics.

It’s part of the workings of the universe so it actually completely normal

mollwollfumble said:

The Rev Dodgson said:

mollwollfumble said:

A seriously interesting speculation. I like it. I can’t see any obvious reason why phonons must have zero mass. They are not like photons that must have zero mass because they travel at the speed of light.

You did?

I strongly disliked it.

To refer to this effect as “strange negative gravity” is just silly.

Yes. I like anything new that isn’t obviously impossible.
Of course. You’re more practical than I am.
Agree, the reporter has hyped it.

If it’s just refraction then it’s the upwards curvature of sound waves that we see all the time in seismic studies.

But I haven’t read the arXiv paper yet.

By the way, we already know that sound waves have positive mass, they possess energy and therefore mass from E=mc ² . So a sound wave will gravitationally attract matter.

When I do read the arXiv paper I find that it’s about sound in superfluids at zero Kelvin. That’s a good starting point.

The authors of the arXiv paper talk about both normal refraction and the mass-energy equation early in the introduction, explaining that this new effect is different from both because of the way that it couples into the equation for GR.

But the resulting equation for the mass looks to me exactly like normal refraction.

I think I see. If we treat normal refraction of sound as due to a negative mass imparted by the variation of the speed of sound with altitude, the this negative mass has a corresponding negative gravitational influence. Hmm, what if the variation of the speed of sound depends on something other than gravity? That isn’t a problem for a superfluid at zero Kelvin, which is where the arXiv article starts, but is a problem in normal matter.

They find the term in the quadratic part of the stress-energy tensor. Hmm.

After reading the arXiv article I find myself sitting on a fence. There’s nothing fundamentally wrong with their mathematics but the stress-energy tensor can hold a multitude of sins. I once looked into the addition of fluid turbulence into the stress-energy tensor, so would this same analysis apply to all forms of fluid motion and not just sound? I don’t know.

In this figure, the upwards curvature of sound waves is interpreted as antigravity. I’m not convinced.