The discussion centers on the distinction between linearized gravity and bimetric theories of gravity within the framework of general relativity. Linearized gravity utilizes a single physical metric, denoted as g, which is expressed as the sum of the flat Minkowski metric and a small perturbation, h. In contrast, bimetric theories propose the existence of two distinct physical metrics. The benefits of bimetric theories, such as exploring varying speeds for electromagnetic radiation and gravitational waves, are acknowledged but not elaborated upon in detail.
PREREQUISITESPhysicists, researchers in gravitational theory, and students studying general relativity who seek to deepen their understanding of the differences between linearized gravity and bimetric theories.
No.dsaun777 said:Is the linearized gravity that describes the gravitational waves of general relativity a bimetric theory of gravity?
No, you're expressing the metric g, to linear order, as a sum of the flat metric and the perturbation. That doesn't mean there are two metrics in the theory. It just means you're expressing the single metric in a useful form given that the perturbation is small.dsaun777 said:Your adding the flat spacetime metric of minkowski spacetime to the perturbed metric, usually denoted h, to arrive at g.
How does this differ from bimetric theory? What's the benefit of a bimetric theory over just adding another dimension to GeneralPeterDonis said:No.No, you're expressing the metric g, to linear order, as a sum of the flat metric and the perturbation. That doesn't mean there are two metrics in the theory. It just means you're expressing the single metric in a useful form given that the perturbation is small.
A bimetric theory says there are two different physical metrics. In linearized gravity there is only one physical metric, g.dsaun777 said:How does this differ from bimetric theory?
I'm not sure what you mean by "adding another dimension to General Relativity", since that has nothing to do with what linearized gravity does.dsaun777 said:What's the benefit of a bimetric theory over just adding another dimension to General
Relativity?
Are there any proponents of the theory here? I'm not suggesting linearized gravity does have any to do with higher dimensions.PeterDonis said:I'm not sure what you mean by "adding another dimension to General Relativity", since that has nothing to do with what linearized gravity does.
As for the benefits of bimetric theory, you would have to ask its proponents.
Not that I'm aware of. If you can give a specific reference to a paper that describes the bimetric theory of gravity you are interested in, you might have a better chance of getting the attention of someone who knows about it.dsaun777 said:Are there any proponents of the theory here?
No specific paper in general. I just wanted to have some people interject their thoughts on a variable a speed of gravity or speed of light.PeterDonis said:Not that I'm aware of. If you can give a specific reference to a paper that describes the bimetric theory of gravity you are interested in, you might have a better chance of getting the attention of someone who knows about it.