black holes

[Anonymous No.3993400]

how come black holes ever form, seeing as how time would slow right down because of gravity as the star collapsed?

pic unrelated

[Anonymous No.3993408]

is that book real?

[Anonymous No.3993412]

>>3993408
i don't know

answer the question

[Anonymous No.3993415]

Well in-terms of knowledge, the concept of black holes even existing is a doxa opinion. Essentially, we only believe they exist because people relating to us Einstein's theory sound credible. If you want lessons in the probable nature of their existence look up max planc's black-body radiation and the theory of relatively ofcourse?

[Anonymous No.3993426]

>>3993415
i don't

i want to know whether, within GR not the real world, they are ever seen to form, or whether time dilation means they are only seen on the cusp of forming, frozen there.

[Anonymous No.3993489]

>>3993426
If a star collapses and forms a black hole then at first the star shines and at some point it doesn't shine anymore. So you observe it. Any objections?

[Anonymous No.3993498]

>>3993489
yes

is this dimming asymptotic, or does an event horizon form

[Anonymous No.3993535]

I'm not 100% what you are asking here. If you just take GR then you certainly can imagine a system of far away particles which come closer and after a time stick together and form a black hole. "later" in this scenario, you'll only see the black hole.


I don't know, maybe this might help in any way:
http://en.wikipedia.org/wiki/Penrose%E2%80%93Hawking_singularity_theorems

[Anonymous No.3993542]

>>3993535
you are not taking into account gravitational time dilation

as the particles come together they will seem to slow down as the gravity is strong.

so they will never get to the point of being a black hole

[Anonymous No.3993604]

I think the answer is that after a finite time the last light ray will escape the body, afterwards it's just black, and yes, you can experience this.

http://people.bu.edu/pbokulic/blackholes/
read 3, I think this might answer it.

[Anonymous No.3993659]

>>3993408
No. Look at the edges of the letters on the spine.

[Anonymous No.3993696]

The simpler question to analyze is "does anything ever fall in?"
http://casa.colorado.edu/~ajsh/schwp.html

[Anonymous No.3993718]

>>3993426
>seen to form
They can't be "seen to form" because light can't escape! The only thing you can literally see is the thing that collapsed. But the light left over from that arrives slower and slower, and eventually the last visible photon leaves, and you only have blackness left.