# B Graviton speed (1 Viewer)

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#### JustWatching

Hi All,
Can somebody tell me what's the speed of the Graviton?
As for Cherenkov Radiation, does exist a similar effect for Graviton?

Thanks

Staff Emeritus
Gravitons are hypothesized to travel at c.

It is far from clear that you can make a medium where the conditions for Cerenkov radiation apply. (Actually, it is certain that there isn't, since there are no negative gravitational charges. What is less clear is if there is some sort of analogous effect)

#### sophiecentaur

Gold Member
Hi All,
Can somebody tell me what's the speed of the Graviton?
As for Cherenkov Radiation, does exist a similar effect for Graviton?

Thanks
For that to occur, you would need to know what the speed of gravitational waves is in a dense medium and then send a massive body into that medium at a higher speed. Sounds like a but of advanced theoretical Physics to me.
But I think that Cherenkov Radiation relates to the wave speed and not the speed of photons.

#### JustWatching

Gravitons are hypothesized to travel at c.

It is far from clear that you can make a medium where the conditions for Cerenkov radiation apply. (Actually, it is certain that there isn't, since there are no negative gravitational charges. What is less clear is if there is some sort of analogous effect)
What do you mean that "it is certain that there isn't, since there are no negative gravitational charges." ?

For that to occur, you would need to know what the speed of gravitational waves is in a dense medium and then send a massive body into that medium at a higher speed. Sounds like a but of advanced theoretical Physics to me.
But I think that Cherenkov Radiation relates to the wave speed and not the speed of photons.
Wouldn't it be easier to just put a Big Mass inside a nuclear reactor, switch the reactor on/off, and measure any force applied to the mass in the two different situation?

Staff Emeritus
The reason you get Cerenkov radiation is because you have a particle traveling faster than light in that medium. The reason the speed of light is slower in media is because you have both positively and negatively electrically charged particles in that medium. There are no particles with negative gravitational charge - i.e. gravity is always attractive, never repulsive. So you can't duplicate the conditions that gave you Cerenkov radiation with gravity.

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