Main Question or Discussion Point
How do you calculate the speed of gravity using general relativity?
Basically, you look at the equations for gravitational waves (in the linearized theory) and show that they travel at the speed of light. At least that's the usual and simplest approach. This is similar to the approach of finding the speed of electromagnetic radiation, and saying that this is the speed of electromagnetism in general.cefarix said:How do you calculate the speed of gravity using general relativity?
I believe that under some extreme conditions one can get gravitational waves in the right sort of dense medium to travel slower than 'c' - however, if one assumes that one has weak waves in empty space, one gets a speed of propagation of 'c' for gravity waves as the above paper illustrates.This implies that equation (17) gives a solution to the wave equation (16)
if [itex]k_a[/itex] is null; that is, tangent to the world line of a photon. This shows
that gravitational waves propagate at the speed of light.