[tony liddicoat (OP)]

is it possible that our universe was given birth inside a black hole in another universe? and each black hole is the birthplace of a new universe?

[evan_au]

That is a hypothesis which has been supported by a number of professional cosmologists.
- It is compatible with Einstein's relativity
- But as yet, we have no evidence that other universes exist
- And we have not yet peered inside a black hole (and even if a brave explorer did go there, they could not report back...)
See: https://en.wikipedia.org/wiki/Black_hole_cosmology

Looking at the beginning of our universe, the entire mass appears to have been in a very compact state.
- That suggests that it started as a black hole
- And since (virtually) nothing can escape from a black hole, we are probably still inside it

[geordief]

That is a hypothesis which has been supported by a number of professional cosmologists.
- It is compatible with Einstein's relativity
- But as yet, we have no evidence that other universes exist
- And we have not yet peered inside a black hole (and even if a brave explorer did go there, they could not report back...)
See: https://en.wikipedia.org/wiki/Black_hole_cosmology

Looking at the beginning of our universe, the entire mass appears to have been in a very compact state.
- That suggests that it started as a black hole
- And since (virtually) nothing can escape from a black hole, we are probably still inside it

If we are in a black hole as you hypothesize,that implies that inside the event horizon there is a more or less infinite number of ways matter can be organized.

So it is only at the very centre of the BH that  the constituent parts of matter become amorphous  and identical to each other?

When two BH's collide  do the internal changes caused mutually one on the other propagate at the speed of light?(Can we say?)

Hope that was not too much gobledegook ;-)

[evan_au]

inside the event horizon there is a more or less infinite number of ways matter can be organized.

Actually, there is a finite amount of entropy/information in a black hole, and the entropy is proportional to the area of the black hole.

Steven Hawking made some progress on analyzing black holes when considering the hypothesis that black holes should not destroy information.
https://en.wikipedia.org/wiki/Black_hole_information_paradox

So it is only at the very centre of the BH that  the constituent parts of matter become amorphous  and identical to each other?

From the viewpoint of someone outside the event horizon of a black hole, spacetime inside a black hole is rather twisted.
- Some hypothesize more than one time-like dimension inside the event horizon.
- From the viewpoint of someone falling into a supermassive black hole, they should not notice a difference immediately
- So we are not really sure what it is like inside a black hole

When two BH's collide  do the internal changes caused mutually one on the other propagate at the speed of light?(Can we say?)

Some very detailed computer modeling was done when designing LIGO, to determine what sorts of signals they could expect to find in different collision scenarios.
- The modeling was apparently very effective, as they now have software that can recognize a collision within seconds
- We can't tell exactly what happens inside the event horizon, but we know that gravitational waves spread out at the speed of light from the collision, carrying a significant fraction of the original mass/energy away with them.
- For example, two black holes originally summing to 65 solar masses formed a single black hole of 62 solar masses; 3 solar masses worth of energy was carried away at the speed of light by gravitational waves.
See: https://en.wikipedia.org/wiki/Binary_black_hole#Observation

[evan_au]

Note: The post from CPT ArkAngel has been split off to What is inside a black hole?, in New Theories.

[bearnard1212]

is it possible that our universe was given birth inside a black hole in another universe? and each black hole is the birthplace of a new universe?

This is a theory that might be possible. Stephen Hawking was the one who supported this version and worked on it
Also, as it has been already mentioned Einstein developed and worked on thi theory either.

[tony liddicoat (OP)]

Assuming our universe began life inside a black hole, the matter being sucked into the BH would have formed its building blocks. There would be no requirement of a big bang as this new matter could be expanding the universe at its periphery.