Black holes and that time thing.

[Dave49]

I have heard that time dialates the closer you get to a black hole. And right at the event horizon time stops from the perspective of an outside observer. So, does this mean that, from our perspective nothing has ever fallen to a supposedly feeding black hole?

[Dave49]

So, I guess there is no official speculation on this?

[Spyman]

The most common case of an event horizon is that surrounding a black hole. Light emitted from beyond the horizon can never reach the observer. Likewise, any object approaching the horizon from the observer's side appears to slow down and never quite pass through the horizon, with its image becoming more and more redshifted as time elapses. The traveling object, however, experiences no strange effects and does, in fact, pass through the horizon in a finite amount of proper time.

http://en.wikipedia.org/wiki/Event_horizon

Edited March 11, 2011 by Spyman

[ajb]

I have heard that time dialates the closer you get to a black hole. And right at the event horizon time stops from the perspective of an outside observer. So, does this mean that, from our perspective nothing has ever fallen to a supposedly feeding black hole?

 

Let us assume we are a large distance from a black hole and that we send a probe off to investigate. Furthermore let us assume that the probe sends back a light pulse at regular intervals (from the probes perspective).

 

What do we see?

 

The light gets red shifted more and more as the probe gets closer and closer to the black hole. The rate at which the pulses are sent also slows down as the probe gets closer to the black hole. This continues for ever, we see more and more red shift, longer and longer time between the pulses. It will take an infinite amount as time as measured by us before we can not detect the probe any more. (Forgetting about the sensitivity of the equipment etc).

 

From the perspective of the probe, it crossed the event horizon in finite time. Moreover it did not notice doing so! The probe just drifted over the horizon smoothly.

[Dave49]

Let us assume we are a large distance from a black hole and that we send a probe off to investigate. Furthermore let us assume that the probe sends back a light pulse at regular intervals (from the probes perspective).

 

What do we see?

 

The light gets red shifted more and more as the probe gets closer and closer to the black hole. The rate at which the pulses are sent also slows down as the probe gets closer to the black hole. This continues for ever, we see more and more red shift, longer and longer time between the pulses. It will take an infinite amount as time as measured by us before we can not detect the probe any more. (Forgetting about the sensitivity of the equipment etc).

 

From the perspective of the probe, it crossed the event horizon in finite time. Moreover it did not notice doing so! The probe just drifted over the horizon smoothly.

 

I take that as a very long way of saying "Yes".