# I Black Holes and Time

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1. Dec 19, 2016

### Will K

So lets say an astronaut was being sucked into a black hole and was able to escape spaghettification and all the death a black hole brings. Since black holes bend space-time itself, the astronaut would experience a differen't time zone than an outside observer (time is relative). The astronaut would see time moving normally, but would see the rest of the universe in a fast forward. Black holes evaporate due to Hawking Radiation, so would the astronaut see the black hole evaporate before he even reaches it? Or would the astronaut experience the black hole in his own time frame, while the rest of the universe sees the black hole evaporate away?

2. Dec 19, 2016

### rootone

A hypothetical indestructable observer gets to meet the singularity shortly after they cross the event horizon.
A few minutes at most, but the view of the entire future of the Universe might be worth the thrills.

3. Dec 19, 2016

### Will K

Yes it would definatly be worth it : ) But in order to reach the singularity of a black hole you must pass the event horizon. The event horizon puts the external universe on an infinite speed to the astronaut. But due to Hawking radiation and dimming cosmic background radiation, the black hole is going to evaporate. This means that the black hole has a life span (as long as the universe is around for it). So the astronaut would see the outside universe speed up infinitely. So as soon as the astronaut passes the event horizon, they will be immediately "transported" to the evaporation of the black hole (final moments). So does the astronaut ever have time to hit the singularity, and see the observable universe?

4. Dec 21, 2016

### Chronos

No, it doesn't work that way. The only way to view the distant future of the universe is to remain stationary near the EH, which is impossible. You must choose your coordinate system carefully to understand what a free falling observer sees during his brief journey into the spaghetti factory. Keep in mind you achieve relativistic velocities as you free fall toward the singularity and the external universe appears redshifted as photons struggle to catch up with you. For further discussion see: http://casa.colorado.edu/~ajsh/singularity.html.

5. Dec 21, 2016

### Will K

Ok, thanks :P