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This question has been closed as not being "mainstream physics". However, this seems to be wrong, since I recently found an interview of Neil deGrasse-Tyson in which he mentions exactly what I said and a book about it (of course, not by the reasoning I used, but with the same conclusion - the book he refers to is "The Large scale structure of space-time" by Steven W. Hawking and George F.R. Ellis. So, it appears it IS mainstream physics)

Back to the original question: Suppose a photon is emitted from some particle of matter that just felt under the event horizon of a black hole, and in the exact direction opposed to the black hole center of gravity.

According to theory, it's speed is lower than the liberation speed, so it cannot escape the black hole, but also according to theory, a photon speed is the speed of light and it cannot be slowed down. It could only be deviated (accelerated) in the direction of the gravitational pull if this one has a preferential side, which it hasn't since by hypothesis, this gravitational pull is only backward and has no side component. This seems to lead to a paradox, since the photon cannot escape a finite space while traveling straight away at the speed of light.

  1. In this situation wouldn't the only solution for the photon being unable to escape the black hole, be that from the inside, a black hole is looking like a universe expanding faster than the speed of light - exactly like our own, in fact? This would lead to the idea that we do NOT need dark energy to explain the growing expansion which would only be a relativity consequence of the huge gravitational pull (since nothing can go above the speed of light, what we see instead of a black hole sucking everything to a singularity, is a growing space time metric so that there is no singularity in it's center - and no center)
  2. In this condition, why wouldn't we suspect that our universe and the big bang, is in fact the appearance that would have the formation of a new black hole (the big bang) and the cosmic microwave background is the residue of the so called white hole, which is itself unobservable, because it is getting away from us faster that the speed of light.
  3. Wouldn't this explain why James Webb Telescope see impossible galaxies which would in fact be images of what the outside of our black whole universe looked at the time of it's formation ?

This would lead to the idea that the general structure of the universe might be that of a huge "foam" of expanding black holes inside one another and permanently eating away their parent universe.

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    $\begingroup$ "According to theory" <-- which theory? $\endgroup$
    – Prahar
    Commented Sep 12 at 10:49
  • $\begingroup$ See here for lots of videos and explanations jila.colorado.edu/~ajsh - as other have said, your assumptions are way off and cannot be used to predict anything. $\endgroup$
    – m4r35n357
    Commented Sep 12 at 12:24
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    $\begingroup$ If you raytrace inside a black hole you see a lot, so your premise is wrong. For an animation that shows how two observers send photons to each other inside the horizon see here. $\endgroup$
    – Yukterez
    Commented Sep 13 at 0:12
  • $\begingroup$ “explain why James Webb Telescope see impossible galaxies” - This is the easy part. When observations don’t match the predictions of the theory, the theory is considered wrong and is discarded to be replaced by a better one. In this case the theory in question is the Friedman cosmology a.k.a. FLRW or Lambda-CDM. This model has been in crisis for a long time with the “dark energy” nonsense, “axis of evil”, Hubble constant discrepancy, and so on. It is long overdue to R.I.P. in the trash bin. $\endgroup$
    – safesphere
    Commented Sep 15 at 4:03
  • $\begingroup$ Your question is still non-mainstream because of your points 2 & 3. You may be interested in the Cosmological natural selection hypothesis (also called the fecund universes) proposed by Lee Smolin. en.wikipedia.org/wiki/Cosmological_natural_selection $\endgroup$
    – PM 2Ring
    Commented Sep 27 at 8:19

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The main difficulty with a question like this is that it seems you are trying to get a qualitative understanding without writing down equations and thinking hard about what they mean. Although it is possible to proceed in this qualitative way in many areas of physics, when it comes to general relativity there's only so much that can be done that way. (The same could be said of quantum mechanics.)

In response to your question about light, the main thing to say about the region inside the horizon of a black hole is that all the null geodesics go to the singularity. Therefore any intuition one might form that is inconsistent with that is a faulty intuition. The mistake here (leading to the faulty intuition) is, I suggest, thinking of the region within the horizon as "a space". It is not. If anything it is "a future" (because the $r$ direction is timelike, in the Schwarzschild case). More precisely, it is a dynamic region of spacetime. To get an impression, or a fairly reliable intuition of the dynamic effect, you can imagine it as like a fluid flowing in the opposite direction to the photon asked about in the question. The photon goes in the 'outward' direction relative to the flow but the flow carries it 'inward'. Note the inverted commas over 'outward' and 'inward' however. Really the singularity is in the future direction and that is the direction the photon heads in. The other direction is the past direction. To see this visually on a diagram, you can use a Penrose diagram for example, which shows clearly which directions are timelike and which are spacelike.

Proceeding to the rest of the question, the mention of the dynamic nature of spacetime on a cosmic scale is relevant, because intuition about one dynamic spacetime can help intuition about another. However these are still two very different solutions to the field equations so it is not clear how much can be learned by comparing them.

The last part of the question reads like speculation without any attempt to connect it to empirical observations by careful reasoning.

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    $\begingroup$ @James - The clock of the body entering the event horizon is unaffected. In fact, any local object falling into a black hole will never even know when it crossed the event horizon -- nothing special happens there (in classical GR). What you are talking about is the fact that the clock of the body entering the horizon appears to slow down to an observer sitting outside the black hole. $\endgroup$
    – Prahar
    Commented Sep 12 at 10:52
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    $\begingroup$ @James - For an observer sitting outside, the clock of the body falling in slows down indefinitely. Therefore, from the POV of an outside observer, nothing ever falls into the black hole. Everything is simply frozen on the horizon. $\endgroup$
    – Prahar
    Commented Sep 12 at 11:23
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    $\begingroup$ @James Comments by Prahar are correct, except for the last one above. In your scenario, the horizon forms at the center and rapidly expands to the surface of the neutron star. There are two equivalent ways to see what happens to the star matter. The first one is intuitively easier. All matter is pushed out by the horizon by linear frame dragging (remember, as observed from outside, nothing can cross the horizon no matter how it moves). The other view is that matter isn’t moved, but an empty bubble of spacetime is created inside while the horizon expands. Either way all matter remains outside. $\endgroup$
    – safesphere
    Commented Sep 14 at 19:02
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    $\begingroup$ The Schwarzschild spacetime inside the horizon is not really “dynamic”. The curvature geometry simply turns the spacetime 90 degrees, that’s it. Time turns from our future to become radial and vice versa, not unlike you bending a sheet of paper with the spacetime diagram on it. This doesn’t make the spacetime “dynamic” - the Penrose diagram is still a static picture, not a movie. I think, “dynamic” usually refers to the curvature changing due to the motion of matter, but this is not the case in vacuum solutions. $\endgroup$
    – safesphere
    Commented Sep 14 at 20:19
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    $\begingroup$ I was using the term merely to mean the metric depends on (and cannot avoid depending on) a time-like coordinate, so one cannot set up a spatial framework or lattice so as to establish a static space that persists. Of course I also accept your points about the situation. $\endgroup$
    – Andrew Steane
    Commented Sep 14 at 21:37

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