# B Would we be able to completely stop time?

1. Aug 11, 2017

### Tryannosaurus

We know that time slows down around a black hole due to its immense gravitational pull that "streches" time, but for the sake of this thread let's say we were able to have an object that had a infinitely strong gravitational pull, would this stop time for good?

Imagine that we created something that could have an infinitely strong gravitational pull but it would only last for 5 seconds, would time around that object completely stop? Then would the 5 seconds it would last for be forever around the object? Would the 5 seconds even matter no that time stopped?

2. Aug 11, 2017

### Orodruin

Staff Emeritus
This is quite an oversimplification.

It is also not clear what you would mean by "infinite gravitational pull". In GR, gravity is the geometry of space-time, not a force.

3. Aug 11, 2017

### elusiveshame

Time doesn't slow down near a black hole, that would be gravitational time dilation. Your clock will still tick at 1 second per second.

4. Aug 11, 2017

### Noel

That answer misses the mark a bit. An observer adjacent to the singularity would observe the external universe age at an accelerated rate, perhaps its entire lifetime, during that second.

5. Aug 11, 2017

### Staff: Mentor

In this case, you have missed the mark. An observer adjacent to the singularity will reach the singularity in a finite (and fairly short) amount of proper time. This observer will not see the entire lifetime of the universe, and in fact the last thing he will see is light that crossed the horizon very shortly after he did.

An observer hovering outside of the event horizon (the horizon and the singularity are different things, of course) can see the entire lifetime of the universe, but only the same way that everyone else can - stick around long enough and you'll get to see everything.

6. Aug 11, 2017

### Orodruin

Staff Emeritus
It should also be mentioned that hovering "just outside" the horizon would require a large proper acceleration, which would somehow have to be imparted on such an observer. The observer would also have to be able to withstand said acceleration. Not a viable way of using gravitational time dilation to see what happens in the future.