are we trying to look out of a black hole when trying to look at the past of the big bang ?

[raphaelh42]

hello, i'm a beginner

we are not able to look inside a black hole, could we see out of it if we were inside ?
when we try to look at the past of the big bang, would we be trying to look at the outside of a black hole from the inside ?

what do you think of about this ?

Are there any theories evoking this hypothesis?

Edited July 14, 2022 by raphaelh42

[Markus Hanke]

7 hours ago, raphaelh42 said:

we are not able to look inside a black hole, could we see out of it if we were inside ?

Yes, light from outside would be able to reach you, but your visual field would be heavily distorted.

7 hours ago, raphaelh42 said:

when we try to look at the past of the big bang, would we be trying to look at the outside of a black hole from the inside ?

No. The global geometry of spacetime used to model the Big Bang is very different from that of a black hole.

[raphaelh42]

13 hours ago, Markus Hanke said:

Yes, light from outside would be able to reach you, but your visual field would be heavily distorted.

No. The global geometry of spacetime used to model the Big Bang is very different from that of a black hole.

ok thank you

[Mitcher]

Black holes and Big Bang are just that : models. In fact the Universe could very well be a black hole as far as we know.

[MigL]

As Markus explained, the geometry is very different.

For a Black Hole, the 'singularity' is always in the future.
For the universe, the Big Bang 'singularity' is in the past.

[joigus]

22 hours ago, Mitcher said:

Black holes and Big Bang are just that : models. In fact the Universe could very well be a black hole as far as we know.

I hope I'm not splitting hairs here in the eyes of the beholder --I know I'm not. But:

 

Not exactly. They're not models; they're predictions of a theory.

Models are assortments of ideas to fit some --previously known-- and desired properties.

Predictions, OTOH, are completely unexpected features of a previously known set of ideas.

Einstein didn't believe in BH's. That's one of two times he was wrong in thinking he got it wrong.

Edited August 18, 2022 by joigus
minor correction

[geordief]

1 hour ago, joigus said:

I hope I'm not splitting hairs here in the eyes of the beholder --I know I'm not. But:

 

Not exactly. They're not models; they're predictions of a theory.

Models are assortments of ideas to fit some --previously known-- and desired properties.

Predictions, OTOH, are completely unexpected features of a previously known set of ideas.

Einstein didn't believe in BH's. That's one of two times he was wrong in thinking he got it wrong.

I remember quite well the time when black holes seemed an outlandish  concept.

What was Einstein's reason for not believing that they existed?

 

I mean be must have known that light  would  not escape the EH and  he knew that spacetime could be curved.

 

What else was needed to satisfy oneself that black holes did in fact exist?

Just experimental evidence?

[joigus]

4 minutes ago, geordief said:

I remember quite well the time when black holes seemed an outlandish  concept.

What was Einstein's reason for not believing that they existed?

 

Einstein abhorred singularities. If my history's right, he thought that his equations must be modified somehow in order to eliminate singularities when the fields become too strong. I think he always clung to the idea that everything wrong with his equations had to do with unifying GR with electromagnetism. He spent many years blissfully ignoring the development of new kinds of interactions (weak, strong). As well as quantum mechanics. But that's another story.

I think that deep down inside, he was a firm believer --with Dirac-- that the mathematical beauty of the theory will tell you what to do next.

[Eise]

1 hour ago, joigus said:

Einstein abhorred singularities

I think it is one step deeper. A black hole limits the knowability of science: it is principally impossible to have empirical knowledge of a black hole behind the event horizon, at least not in a way that it can become part of science (of course you possible could dive in a super-massive black hole without spaghettification, but you cannot come back to inform scientists about what you saw or measured...). My recent readings on the interpretation of QM seem to make a similar point for Einstein: he could not accept the 'spooky action at a distance'. For him there had to be some hidden variables that would explain it. Something has to be there, but that it is empirically outside our reach was not acceptable to him.

[Mitcher]

On 8/17/2022 at 3:00 PM, MigL said:

As Markus explained, the geometry is very different.

For a Black Hole, the 'singularity' is always in the future.
For the universe, the Big Bang 'singularity' is in the past.

Couldn’t it be that the Universe’s topology forms quite a unique and unparalleled object ? Its inside and ouside could be indistinguishable for instance, with a single, not permeable membrane seen as the Planck’s wall from one side and as the BB horizon on the other one. Just running wild on that one.

[joigus]

41 minutes ago, Eise said:

I think it is one step deeper. A black hole limits the knowability of science: it is principally impossible to have empirical knowledge of a black hole behind the event horizon, at least not in a way that it can become part of science (of course you possible could dive in a super-massive black hole without spaghettification, but you cannot come back to inform scientists about what you saw or measured...). My recent readings on the interpretation of QM seem to make a similar point for Einstein: he could not accept the 'spooky action at a distance'. For him there had to be some hidden variables that would explain it. Something has to be there, but that it is empirically outside our reach was not acceptable to him.

I would agree with that. This is what Einstein didn't like:

IOW, whatever objective limits to knowledge. You absolutely cannot know what's behind this curtain.

It would be very interesting to know what Einstein and Gödel talked about when they took those long walks by the campus of Princeton. Here's the mathematician who proved that there are things in maths that are not for us to know, and the physicist who always dreamed everything could be understood.

Then Hawking and Penrose found out that singularities are (almost?) inevitable, but always hidden behind horizons. It's an interesting pattern. As @MigL correctly said, they sometimes draw a curtain on the remote past (cosmic singularity), and sometimed towards the future (BHs).

If I'm allowed to take sides, I would borrow Einstein's optimism, that we will understand more if we come up with the right mathematical mapping of maths to physical reality. In that direction, there's a very interesting formulation of GR --called Plebanski's formulation-- some developments of which strongly suggest complex numbers.

It's one thing to know that you shall not pass, but understanding why, and a very different thing just to know that you shall not pass. Then you just look silly.

[MigL]

On 8/18/2022 at 11:54 AM, joigus said:

If I'm allowed to take sides, I would borrow Einstein's optimism, that we will understand more if we come up with the right mathematical mapping of maths to physical reality.

I prefer N Bohr's 'pessimism'.

God does play dice with the universe, and sometimes throws the dice where they cannot be seen.

[Mitcher]

34 minutes ago, MigL said:

I prefer N Bohr's 'pessimism'.

God does play dice with the universe, and sometimes throws the dice where they cannot be seen.

We are ants lost inside a nuclear power station but give us another 50 millions years of intelligent evolution and we willl see it.

[joigus]

22 minutes ago, MigL said:

I prefer N Bohr's 'pessimism'.

God does play dice with the universe, and sometimes throws the dice where they cannot be seen.

Oh, I think Bohr's pessimism will never be rebutted as a factual constriction of Nature. But Bohr has been a little bit obscure to me at times when trying to explain why. But we're getting off the tracks here, because I don't think he ever gave much thought to black holes.  

Although, as Markus knows well, and you probably do too, there may be a connection between complementarity and BH's through the EPR = ER principle.