- #1
sillycow
- 18
- 1
I have some questions regarding things that boggle my mind about black holes. These things seem to me like paradoxes, and I was wondering if someone could explain them.
1. How do you measure the distance to a black hole? As far as I understand the distance to a black hole is defined as the distance from an observer to the event horizon. Distance, in physics is defined by the time it takes light from point A to reach point B. However, as time is dilated close to the event horizon, no observer will ever see anything fall into the black hole. An observer would just see things red-shifted and slowing down. Meaning: "Light would take an infinite amount of time to travel *into* the black hole. Wouldn't that mean that the black hole is infinitely far away from any observer? (farther away than things which are "behind" the black hole)
2. This one involves several "paradoxes"
2a. As you approach the event horizon, it keeps moving away from you (space-time gets increasingly curved).
2b. If you look at someone falling towards an event horizon, they slow down until they almost freeze.
==>
2c. That leads me to believe that no observer can ever observe any object to cross an event horizon. How can a black hole come into existence, if it wasn't there beforehand. Or in other words, if nothing can be seen to cross an event horizon for any observer, how can an event horizon exist?
3. Not really a paradox, but a "cool question". If I stand in between 2 black holes (not inside their event horizons), in the exact point where their gravity nulls each-other out. Assuming I am a point particle... Do I get double the time dilation compared to someone standing far away? Or 0 time dialation?
1. How do you measure the distance to a black hole? As far as I understand the distance to a black hole is defined as the distance from an observer to the event horizon. Distance, in physics is defined by the time it takes light from point A to reach point B. However, as time is dilated close to the event horizon, no observer will ever see anything fall into the black hole. An observer would just see things red-shifted and slowing down. Meaning: "Light would take an infinite amount of time to travel *into* the black hole. Wouldn't that mean that the black hole is infinitely far away from any observer? (farther away than things which are "behind" the black hole)
2. This one involves several "paradoxes"
2a. As you approach the event horizon, it keeps moving away from you (space-time gets increasingly curved).
2b. If you look at someone falling towards an event horizon, they slow down until they almost freeze.
==>
2c. That leads me to believe that no observer can ever observe any object to cross an event horizon. How can a black hole come into existence, if it wasn't there beforehand. Or in other words, if nothing can be seen to cross an event horizon for any observer, how can an event horizon exist?
3. Not really a paradox, but a "cool question". If I stand in between 2 black holes (not inside their event horizons), in the exact point where their gravity nulls each-other out. Assuming I am a point particle... Do I get double the time dilation compared to someone standing far away? Or 0 time dialation?