I'm reading "The Large Scale Structure Of Space-Time" by Hawking and Ellis<p>One question is whether there is a singularity at the "bottom" of a black hole.<p>It seems to me that the gravitational collapse at the singularity of a black
hole would match the "trigger event" of the creation of our Universe.<p>Within the (our) black hole there would be a singularity event which appears to
us as the "creation of our Universe". Within such a black hole several effects
likely occur.<p>One is the "hologram" idea (https://www.scientificamerican.com/article/is-our-universe-a-hologram-physicists-debate-famous-idea-on-its-25th-anniversary1/) which posits that
our universe’s 4D spacetime could be a holographic projection of a lower-dimensional reality. This would fit nicely if the "surface" of the hologram was the "surface" of
the inside of our black hole.<p>Another question arises as to whether the Universe is "infinite" and "what is it
expanding into". Time and space would be extended toward the boundary of our black
hole and would appear "infinite" but give something to "expand into" as both space
and time would be changed when approaching the interior boundary of the hole. The
boundary would appear to be "infinitely far away".<p>There could likely be other "universes" within other black holes both within our
current black hole and/or within black holes "outside of our universe".<p>The "curvature of space-time" and the phenomena of "gravity" can be due to the
"shape of the hole" from the inside.<p>The "cosmic background radiation" could be due to Hawking radiation at the boundary
where we see the particles that did not escape yet never able to see the corresponding
particle that "boils off outside" our black hole.<p>I refer to the idea of the Universe existing in "our black hole" as the Calcutta theory.<p>Tim Daly
>A black hole cosmology (also called Schwarzschild cosmology or black hole cosmological model) is a cosmological model in which the observable universe is the interior of a black hole. Such models were originally proposed by theoretical physicist Raj Kumar Pathria, and concurrently by mathematician I. J. Good.<p><a href="https://en.wikipedia.org/wiki/Black_hole_cosmology" rel="nofollow">https://en.wikipedia.org/wiki/Black_hole_cosmology</a>
I recall reading about how our universe could be a "bubble" jostling with other universes in a metaverse. Perhaps the blackhole that is being postulated exists in 4 or maybe more dimensions.