# Time dilation

1. Feb 22, 2008

### Tuugii

I have one more questions, I really don't get the concept:

Show that a local observer far from the black hole ages at the same rate as the observer
at infinity and that the former’s aging rate stops in comparison with the latter’s when
the event horizon is approached.

thanks a lot,
T

2. Feb 22, 2008

### smallphi

Imagine that each observer emmits pulses each second of his local clock. The observer at infinity will notice that the pulses coming from the one approaching the horizon get more and more rare and completely stop when he gets at the horizon. I guess that's what the problem is asking, although the wording is very impresize, even creating wrong idea.

The local aging rate never stops for any observer. If one is in a rocket that crosses the horizon, he won't 'stop living' all of a sudden. In fact, he won't feel anything special, not even a jitter. Only inside the horizon, he won't be able to send messages to outside and soon the strong gravitational gradient will stretch his body and kill him.

3. Feb 27, 2008

### maxwilli06

I'm going to take a swing at it too, even though i don't understand the question completly.

Simply put, I believe this question is asking about the difference of experiences between each observer in relation to the other.
Due to GR, the observer approaching the black hole would appear to slow down to an observer watching him outside of the gravitational force of the blackhole. For the observer near the blackhole, the observer outside would appear to speed up. With gravity reaching infinity in the blackhole, the observer entering it completly would reach the end of time.

I am an amateur so don't beat down on me if this has nothing to do with the question.

4. Mar 3, 2008

### petm1

Thinking of a black hole, large mass in a small space, I think of how much time dilates when the mass goes to infinity, that singularity of mass is an eternity of time. IMO the observer entering the blackhole would never reach the end of time.