0
votes
1answer
70 views

Boundaries of Black Hole and Observable Universe

Are the boundaries of a black hole, the event horizon, similar to the boundary at the end of our observable universe?
0
votes
2answers
37 views

Are the cosmic horizons observer-specific?

It is known that all observers will agree on the position of the black hole event horizon. But what about the cosmic horizon of the de Sitter space? Can one say that the horizon of scientist1 is ...
9
votes
1answer
236 views

How deep is the region near an event horizon where Hawking radiation is generated?

In other words, how strong does gravity have to be to cause Hawking radiation to occur?
2
votes
1answer
120 views

Cosmic event horizon

I had a question regarding cosmic event horizon. Let's say that a far away solar system has just crossed the cosmic event horizon due to the expansion of the universe. In that solar system let us ...
1
vote
2answers
179 views

Second law of thermodynamics implies a linear cosmology?

If one applies the second law of thermodynamics to the Universe[1] as a whole then one might expect that the entropy of the Universe always increases as time goes forward (or more accurately that the ...
3
votes
2answers
324 views

What is the current radius of cosmological event horizon?

Doing some crude calculations (using the value of $H_0$ at this point of time only, since it is time dependent but not distance dependent thanks to Johannes answer) what is the radius of cosmological ...
0
votes
2answers
100 views

Causal reconnection

Can causally disconnected regions join up again? For example the universe is expanding faster than light creating cosmological horizon, but what if something causes the expansion to slow down and ...
6
votes
2answers
305 views

Will acceleration rate of expansion of space become faster than speed of light?

From watching cosmology lectures, it seems that the space between galaxies is expanding at an accelerating rate, my question is since it is the space that is (acceleratingly expanding), the special ...
3
votes
1answer
235 views

Could a ship equipped with Alcubierre drive theoretically escape from a black hole?

Also could it reach parts of the universe that are receding faster than the speed of light from us?
9
votes
3answers
653 views

Is the observable region of the universe within the event horizon of a super-massive black hole?

Observations: I have read that for a free-falling observer within the event horizon of a black hole that all lines of sight will end at the singularity which is black. I also look up and see that ...
6
votes
4answers
537 views

de sitter cosmologic limit

It has been said that our universe is going to eventually become a de sitter universe. Expansion will accelerate until their relative speed become higher than the speed of light. So i want to ...