The discussion revolves around the relationship between linearized gravity, which describes gravitational waves in general relativity, and the concept of bimetric theories of gravity. Participants explore whether linearized gravity can be considered a bimetric theory and discuss the implications of such a classification.
Participants do not reach a consensus on whether linearized gravity qualifies as a bimetric theory. Multiple competing views remain regarding the definitions and implications of bimetric theories versus linearized gravity.
The discussion highlights limitations in understanding the distinctions between linearized gravity and bimetric theories, as well as the implications of dimensionality in general relativity. There are unresolved questions regarding the benefits and interpretations of these 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.