It is said that as a massive star collapses, it appears to become increasingly red-shifted over time, as well as vanishingly dim. An outside observer will percieve the star to be eternaly collapsing as Alex said, therefore, as with gravity, one should always be able to still detect escaping photons (has nothing to do with Hawking/Bekinstein radiation). This could be interpreted as saying that a blackhole never actualy turns completely black, but simply "asymptotically approaches" the appearence of being black. (Once again, please ignore Hawking-radiation phenomenon).

So my question is, why doesn't the same happen for graviton as does for photon? In other words, electromagnetic propogation grinds to a hault as escape velocity approaches c; why not the graviton as well?
Taking as a direct analogy... the graviton should become increasingly red-shifted over time, as well as G-field becoming vanishingly dim. Why does "gravitational signal" escape the clutches of blackhole (unscaved), while electromagnetic signal can not?

• Its not a gravitational signal.. - bruce - October 27, 2001 - 13:47 UTC