# Negative Gravity?

#### Treversal

##### Junior Member

QUOTE

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.”

#### Treversal

##### Junior Member
So a rotating CASIMIR HOOP also needs "A Space Odyssey" played "around it"?

#### Treversal

##### Junior Member
So a rotating CASIMIR HOOP also needs "A Space Odyssey" played "around it"?

#### Harte

##### Senior Member
Phonons are hypothetical particles envisioned to stand-in for real particles such as photons.
All phonons can do is illustrate what real particles do.

So this effect would need to be demonstrated with actual particles for any meaning to be assigned to it.

Harte

#### Einstein

##### Temporal Engineer
Negative gravity=Centrifugal force

#### Kairos

##### Active Member
Negative gravity=Centrifugal force
I think negative gravity would be more like a stretching of space-time. Gravity is just curving downward (pinching of space-time) whereas, I guess, negative gravity would be space-time curving upwards (stretching).

#### Harte

##### Senior Member
Okay.
Now, which way is "up?"

Harte

#### Kairos

##### Active Member
Up and down are just subjective ways of visualizing the pinching and stretching of spacetime.

If there were such a thing, up and down would be along a fourth dimensional axis.

But I think it a mistake to confuse the common visualization (model) of spacetime with the reality. The math is where it's at, but I have not messed around with tensors since grad school, so that's not happening.

#### Treversal

##### Junior Member
Negative gravity=Centrifugal force
If sound waves have negative gravitational mass then two sound waves would REPEL each other? The way everything with positive gravitational mass ATTRACT each other?