Question

Could some one explain what red-shift really means when we're talking about the EH of a BH?

Answer 1

EH= Event Horizon
BH= Black Hole

Answer 2

Are you familiar with the gravitational doppler effect at all?

Answer 3

Oh! In which case you have to understand that observers under higher gravitation appear time dilated to observers under lower gravitation. So those of us watching an observer falling into a black hole will see that observer slow down (and, in fact, if I understand correctly, never cross the event horizon), and any sort of waves they send back will have more infrequent peaks due to the time dilation. And so we see redshift in light waves.

Answer 4

@suresh006
you just copied some else.... I asked the same question on PH.

@Jemurray3
just briefly in school.

Answer 5

u got answer ,n right answer doesn't have copy right mind it

Answer 6

The basic idea above is right. The acceleration one feels on the surface of the earth is equivalent to the acceleration one would feel in a box accelerating upward in empty space. This leads to the idea of gravitational redshift, which is the shift of electromagnetic radiation emitted in a gravitational field towards the red end of the spectrum. See http://en.wikipedia.org/wiki/Gravitational_redshift .

For the event horizon of a black hole, you would just take this to the most extreme case. The wavelengths of light would become longer and longer until finally those emitted from the event horizon ceased to exist at all.