Graviton: Energy, Impulse, Frequency & Quantum

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In summary, gravitons are hypothetical particles that arise in theories of quantum gravity, but they are not based on wave mechanics.
  • #1
mersecske
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Graviton is an analogy or an exact object in he framework of classical GR?

What bout the energy and impulse of a graviton with frequency nu? What is the quantum?
 
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  • #2
Gravitons do not arise from classical GR. GR is not quantized.
 
  • #3
So what is a graviton? And in which kind of theory? And what is the most useful formulas, like energy as a function of frequency?
 
  • #4
The best thing we can do up to now, is to linearize GR (which gives a theory called "Fierz-Pauli") and try to quantize it. The particle associated to this quantization is called the "graviton", and should be massless and have spin 2.

So the theory a graviton in appears is in this case "linearized GR".

However, string theory claims to be a UV-complete (so beyond the linear level!) theory of quantum gravity, and also has a graviton in its spectrum. At low energies, so at the linear level, it reproduces linearized GR.

What "the energy of a graviton" would be is a tricky question due to the equivalence principle; I would have to think about that.
 
  • #5
Are there any useful equations for gravitons like E=h*nu for photons?
 
  • #6
The graviton is a hypothetical particle in certain theories about quantum gravity.

Naive (perturbative) quantization of GR leads to a theory (unfortunately ill-defined in the UV) which is based on gravitons.
String theory leads to low-energy effective theories (SUGRA) which contain both spin-2 gravitons and their SUSY-partner, the spin-3/2 gravitino.
Other theories regarding quantum gravity, e.g. LQG, use very different concepts, and gravitons are not their basic building blocks but do emerge only in a certain semiclassical limit.
 
  • #7
It is not possible to introduce graviton simply based on wave mechanics?
 
  • #8
No, because you wouldn't know the properties of the graviton. According to GR, gravity is propagated by tensor modes.
 
  • #9
But I have read lots of papers in which graviton are mentioned,
like 1-2 graviton is emitted in the process for example.
 
  • #10
Wave mechanics is a concept of QM, but the graviton is a concept based on (second quantized) QFT. There is no photon in Maxwells theory.
 

1. What is a graviton?

A graviton is a theoretical particle that is thought to be the carrier of the force of gravity. It is predicted by some theories, such as string theory, but has not been directly observed or detected.

2. How does a graviton relate to energy?

According to quantum theory, energy is carried by particles, including the graviton. As gravity is a force that acts over a distance, it is thought to be mediated by the exchange of gravitons between objects.

3. What is the relationship between gravitons and impulse?

Impulse is a measure of the change in momentum of an object. Gravitons, being particles, have momentum and can transfer this momentum to other particles through the force of gravity. Therefore, the exchange of gravitons can result in changes in impulse.

4. What is the significance of frequency in relation to gravitons?

The frequency of a particle refers to the number of oscillations or vibrations it undergoes per unit of time. In the case of gravitons, frequency is related to the energy of the particle. Higher frequency gravitons would carry more energy and therefore have a stronger effect on objects.

5. How does quantum theory explain gravitons?

Quantum theory describes the behavior of particles at a subatomic level. In this framework, gravitons are seen as virtual particles, meaning they can appear and disappear over short distances and timescales. This explains how the force of gravity can act over large distances, as the exchange of virtual gravitons can occur between objects without the need for physical contact.

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