# Graivton quantization

1. Feb 23, 2012

### serp777

Theoretically, how much energy in particle accelerator would be required to quantize a graviton from a gravity field?

2. Feb 23, 2012

### mathman

I doubt if anyone knows the physics behind your question.

3. Feb 23, 2012

### negru

Probably somewhere around the Planck scale (10^19 GeV)

4. Feb 24, 2012

### serp777

Any reason why the graviton would require so much more energy to become quantized?

5. Feb 24, 2012

### tom.stoer

This is the natural energy scale EPl; a theory of quantum gravity at a different scale EQG = xEPl with x << 1 would have to explain the smallness of x.

6. Feb 24, 2012

### Bill_K

Q. How much energy does it take to create a photon?
A. ħω, where ω is the frequency of the photon.

Q. How much energy does it take to create a graviton?
A. Exactly the same, ħω.

Q. Well then, how come particle colliders create scads of photons but no gravitons?
A. It's not the energy that's the problem, it's the production rate. Photons are produced (primarily) by time-dependent electric dipoles. Gravitons are mainly produced by time-varying mass quadrupoles. You can crash two protons together and calculate their mass quadrupole moment as they collide, and then multiply that by the gravitational constant G to get the production rate. It's ridiculously small.

Q. What does the Planck mass have to do with it, if anything?
A. The Planck mass is the energy at which (presumably) gravitational interactions become comparable to the strong and weak interactions. So yes, you'd need a collider with that energy if you wanted to make the production rates comparable. But spacetime literally goes to pieces at that energy. If you really want to make gravitons, run at a much lower energy and be prepared to wait.

7. Feb 24, 2012

### serp777

If the production rate of a graviton is determined by the mass quadrupole * G, then wouldn't the graviton be much more likely to be detected if you placed a particle accelerator very close to a dense object, such as a neutron star or a black hole? (Since the value of the quadrupole function becomes larger as mass, and therefore gravitational attraction, increases). My bet is that there is an equilibrium near an event horizon, where gravitons are likely to be quantized.