3 ms·
I think I read somewhere that gravity waves travel at the speed of light. Does anyone know if they can be slowed down like light through glass/other materials?
by concernedctzn 12y ago
I think I read somewhere that gravity waves travel at the speed of light. Does anyone know if they can be slowed down like light through glass/other materials?
- antognini 12y agoYes, there is an index of refraction for gravitational waves passing through matter. As the gravitational wave passes through, particles in the material oscillate, producing their own gravitational waves. The combined gravitational wave from the original gravitational wave plus the secondary gravitational waves is broader. The increased wavelength implies a decreased speed. An idealized equation for this index of refraction can be found in Eq. 18 here: http://link.springer.com/article/10.1007%2FBF00891464#page-1 http://link.springer.com/article/10.1007%2FBF00891464#page-1 The paper calculates the index of refraction for the Earth and finds that n - 1 ~ 10^-17, so it's a very small effect indeed. For something much more dense and stiff, like a neutron star, it would be higher by many orders of magnitude. But without knowing the equation of state of a neutron star it's impossible to calculate n.