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So it's my understanding that the current models predict that a super massive object will collapse beyond the event horizon into a singularity of infinite density.

My question is the following: isn't such a prediction contradicted by the observable universe, since we observe expansion from the Big Bang? How could a singularity form if at some point in time there was a much more massive and dense object (the Universe) that did not remain or achieved singularity but inflated ?

edit 1: Or in other words, as Tom B. suggested [but see edit 2]:

IF the universe was inside of its own event horizon, which seems reasonable given its huge mass and tiny size just after the big bang, how did it escape?

edit 2 [edited a bit the initial question, comments below]: I believe this question is different from Big Bang snuffed by a black hole? question, because I'm not suggesting that the forces leading to black hole formation would counteract the Big Bang.

I'm indicating that there are two potential instances of singularity in the Universe, the Big Bang t0, and black-hole singularities. The Big Bang singularity (if it ever existed) is not stable and can be observed to have degraded into inflation.

Similarly, shouldn't this observation lead one to think that a black-hole singularity, if formed, would lead to a similar inflation? I understand that the black-hole environment is not homogenous whereas the big-bang conditions were mostly homogenous, but from both singularities' referentials would that matter?

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marked as duplicate by tfb, Kyle Kanos, Emilio Pisanty, Ben Crowell, sammy gerbil Feb 23 '18 at 16:49

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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    $\begingroup$ At what level of math do you want an answer? So it's my understanding that the current models predict that a super massive object will collapse beyond the event horizon into a singularity of infinite density. This is not true, but we would need to know at what level to explain why not. $\endgroup$ – Ben Crowell Feb 22 '18 at 1:05
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    $\begingroup$ "How could a singularity form if at some point there was a much more massive and dense object (the universe)" - is (the universe) an object? $\endgroup$ – Alfred Centauri Feb 22 '18 at 2:27
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    $\begingroup$ Seems like a fair question. In other words, IF the universe was inside of its own event horizon, which seems reasonable given its huge mass and tiny size just after the big bang, how did it escape? $\endgroup$ – Tom B. Feb 22 '18 at 5:10
  • $\begingroup$ Tom B. reformulated my question perfectly, I'll add his question to the main question. ~ $\endgroup$ – Alexandre F. Santos Feb 22 '18 at 7:58
  • $\begingroup$ Ben, I'm not a physicist, so a low level of math would be best for me, if you can. $\endgroup$ – Alexandre F. Santos Feb 22 '18 at 7:59
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Isn't the Big Bang contradictory with the existance of singularities in black holes?

The question assumes that in general relativity there is only one kind of singularity. This is not true.. From the abstract:

Seminar held at JINR, Dubna, May 15, 2012.

In General Relativity, spacetime singularities raise a number of problems, both mathematical and physical. One can identify a class of singularities - with smooth but degenerate metric - which, under a set of conditions, allow us to define proper geometric invariants, and to write field equations, including equations which are equivalent to Einstein's at non-singular points, but remain well-defined and smooth at singularities. This class of singularities is large enough to contain isotropic singularities, warped-product singularities, including the Friedmann-Lemaitre-Robertson-Walker singularities, etc. Also a Big-Bang singularity of this type automatically satisfies Penrose's Weyl curvature hypothesis.

Italics mine.

Black hole singularities are simple to visualize, a very large mass suffers a gravitational collapse to a single point. The singularity that generates the Big Bang has different general relativity geometrical features .

The particular singularity model for the Big Bang was chosen because the observations pointed to an expanding universe, and an explosion from a singularity could model the data when first proposed.Thus the Big Bang singularity mathematically differs from a black hole singularity, because the observed behavior of matter differs. In a black hole there is contraction to a singularity, in the Big Bang explosion from a singularity. Different mathematical models.

At the present Big Bang model the singularity is fuzzy from expected quantum mechanical effects ( once gravity is quantized ) which also create the inflation period, necessary for modeling the homogeneity of the microwave background radiation.

p.s. this is an interesting read,, under copyright so I cannot copy it.

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