Approaching a Black Hole

1. Jun 20, 2007

kuahji

In the popular science books/magazines I read, they often state that as one approaches the even horizon, eventually an observer will see an object, person, etc. freeze, as if time has stopped. But, the thing crossing crossing the horizon doesn't notice any effects (besides tidal forces & things of that nature).

Anyway, we see things around black holes such as accretion disks (or at least what we think are black holes). Wouldn't the accretion disk also appear to freeze, or slow down the closer it comes to the black hole? If so, do these effects show up in the data scientists have collected already? Just curious about this phenomenon.

2. Jun 20, 2007

pmb_phy

A Schwarzschild observer (Observer at rest at infinity) would observer the time as measured on a wristwatch on a person falling into the black hole. Theoretically this observer comes closer and closer to the event horizon as time increases but will never cross it. But this is as observed by a Schwarzschild observer. As recckoned by an observer who is falling into the black hole will observer his wristwatch to be running as usual.
A Schwarzschild observer will see the matter falling into the black hole but the closer the object is to the event horizon the Schwarzschild observer will see an increasingly redshifted effect of the falling object. This means that eventually the redshift will be so great that a Schwarzschild observer will never observer matter just outside the event hoirizon. So the matter of an accretion disk will always appear to be moving.

Best regards.

Pete