I never understood how gravitational redshift works for an electromagnetic wave leaving the source of gravity. I don't see how the frequency of the wave can be changed by space-time warping. If the "path" is what changes, how can the wave that's travelling over the path be changed too? I could see it affecting gravitational waves, because those are ripples IN spacetime, but I don't get how it works for electromagnetic waves.

 

Thanks

I do not fully understand your question. Are you familiar with the redshift (e.g. could you calculate the redshift occuring when I point a laser pointer towards a satelite) and want to discuss the results or haven´t you seen the math, yet? Imho, redshift can be purely considered an effect of gravitational time dilatation leaving the EM wave (in a suitable coordinate system) basically unchanged but letting the observers do different measurements on it.

I´m pretty fu... tired right now so I´ll not elaborate for now. I´ll setup a little explanation of gravitational redshift the next days unless you already know the math.

I never understood how gravitational redshift works for an electromagnetic wave leaving the source of gravity. I don't see how the frequency of the wave can be changed by space-time warping. If the "path" is what changes, how can the wave that's travelling over the path be changed too? I could see it affecting gravitational waves, because those are ripples IN spacetime, but I don't get how it works for electromagnetic waves.

 

The wavelength (inversely, frequency) is also characterized by a time parameter as well as spatial ones, and remember that we're talking about a path through space-time.

I set up a little explanation, there we go: http://www.wisci.org/wiki/Redshift#Gravitational_Redshift .

Ok, thanks a lot both of you. Everything is pretty clear now.

Thanks, I also get it now

The correct answer can be described conceptually, without the math. Take a look at chapter 3 in Melia's "The Black Hole at the Center of Our Galaxy."