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.
Linearized gravity is a simplified version of Einstein's theory of general relativity, which describes the effects of gravity on a small scale. It is based on the assumption that gravitational fields are weak and can be treated as small perturbations on a flat background spacetime.
Bimetric theory is a modification of general relativity that introduces a second, independent metric tensor to describe the gravitational field. This allows for the existence of two different gravitational fields, one associated with each metric tensor, and can potentially explain phenomena that cannot be explained by general relativity alone.
Linearized gravity has many applications in physics, including in the study of gravitational waves, black holes, and the early universe. It is also used in the development of theories of quantum gravity, which aim to reconcile general relativity with quantum mechanics.
Linearized gravity can be tested and validated through a variety of experiments and observations, such as the detection of gravitational waves, the study of the motion of celestial bodies, and the measurement of the cosmic microwave background radiation. These tests help to confirm the predictions of the theory and rule out alternative explanations.
One of the main challenges of bimetric theory is that it is difficult to reconcile with the principles of general relativity, such as the equivalence principle. Additionally, there are still many unanswered questions and uncertainties surrounding the theory, and more research is needed to fully understand its implications and limitations.