Is Gravity a Particle or a Spacetime Phenomenon?

[YoungDreamer]

I have a question about gravity.
Why do we think that gravity is caused by a specific particle.
Why isn't gravity considered a phenomenon related to the way matter interacts with spacetime.

 

[Nabeshin]

I have a question about gravity.
Why do we think that gravity is caused by a specific particle.
Why isn't gravity considered a phenomenon related to the way matter interacts with spacetime.

So, you have to understand how field theories and their quantization works. Gravity, as a classical field theory, is well described by Einstein's theory of General Relativity. In this theory, gravity is precisely what you say -- the curvature of spacetime, there are no particles or anything else to speak of. Now, when there are changes in the gravitational field, we see these as ripples propagating in the fabric of spacetime: gravitational waves.

In electromagnetism, we have a similar situation. We have a nice electromagnetic field, but changes in that field propagate outwards as electromagnetic waves. In the quantum view of this scenario, the EM wave are identified with particles -- namely, photons. Analogously with gravity, gravitational waves are identified with particles -- gravitons.