Why do I never hear that the BB was caused by a collapsing black hole?

[Tzikin]

Even before I had seen a Kaku documentary on black holes creating new universes, perhaps with different physics on the other side of them, I had had this image that the Big Bang was caused by a collapsing point singularity in a parent galaxy.
Surely there must be something wrong with this simple theory.
It seems to have another corollary in that it could explain the elusive negative energy that is the source of much hypothetical speculation. It would suggest that spatial structure is still coming through the black hole, sucked in from the parent universe and redistributing itself. Galaxies are concentrated by their central black holes having the opposite effect, reducing the space around them.
It sounds too obvious. Somebody must have suggested it and others shot it down before it really came into the public domain.
Could somebody please explain why I am wrong.

 

[skydivephil]

There are such proposals, here are two examples:
http://evodevouniverse.com/wiki/Cosmological_natural_selection_(fecund_universes)
http://www.insidescience.org/content/every-black-hole-contains-new-universe/566

I should add that its true that people have proposed this idea, it hasn't exactly gained traction in the community. It doesn't mean they are wrong but the arguments are clearly not strong enough to be convincing. A problem is that big bang singularities are some what different to black hole singularities. Again this doesn't mean those theories are wrong and I'm sure the people that proposed these ideas know this but it should give us caution in trusting our intuition that the two are the same.

 

[Tzikin]

Thank you. It seemed a little obvious. Big Bang - point singularity, black hole - point singularity. Now that we are in an era of multiverse theories, it would not matter too much if the Big Bang were no longer the beginning.

However, I cannot see anything in the references that use this to explain Negative Energy. Could space continue to be pulled through a black hole to expand the other universe?

 

[bapowell]

The big bang was not a point singularity.

 

[Tzikin]

There are such proposals, here are two examples:
http://evodevouniverse.com/wiki/Cosmological_natural_selection_(fecund_universes)
http://www.insidescience.org/content/every-black-hole-contains-new-universe/566

Apparently, there are those that think that it could have been a Point Singularity, as in another name for a black hole and I did not think that we could state what it was or what it was not before the Big Bang with any certainty. Wiki uses the term singularity to describe the BB and it is a point with no dimensions (as we know them) from as far as I can tell.

However, I was making a visual and conceptual point that it is not too great a leap to make between the singular, dimensionless point and a black hole, a Point Singularity.

The question that remains is whether there could still be an outpouring of space through a black hole that could explain negative energy and an inpouring of space around the central black holes in the centre of each galaxy that clusters the stars by counteracting this negative energy, effectively giving black holes a greater 'gravitational effect' on space time than their mass alone would suggest.

 

[Mordred]

Google Poplowski. He developed a universe inside Bh event horizon model. Using what he terms torsion and spin.

http://www.nikodempoplawski.com/publications.html

 

[bapowell]

Apparently, there are those that think that it could have been a Point Singularity, as in another name for a black hole and I did not think that we could state what it was or what it was not before the Big Bang with any certainty. Wiki uses the term singularity to describe the BB and it is a point with no dimensions (as we know them) from as far as I can tell.

No, this is wrong. "Singularity" does not mean "point". It refers to parts of the physical manifold at which the theory essentially breaks. The only thing that big bang and black hole singularities have in common is that they are spacelike; you should not ascribe similar physics to them because the theory doesn't work at either one. The expectation is that a complete quantum theory of gravity will "resolve" these singularities by replacing them with an operative physical theory.

Is it your conception that the big bang happened at a point, and this is why the singularity itself should also be a point? If so, this is a very common misconception -- the big bang did not occur at a single point, but everywhere at once.

 

[Naty1]

A simple way to think about the answer to your question is that the singularities are likely different: the BB is the beginning of stuff and a black hole is the end of stuff...At the BB everything is expanding, at a BH everything is condensing...it is thought they exhibit different spacetimes...Penrose says they have very different curvatures via his Weyl curvature hypothesis [explained in the link below]...note that spacetime curvature is gravity. Brian Greene says:

The big bang theory says nothing about time zero itself. It turns out that in the right environment gravity can be repulsive. Not only mass but energy and pressure also contribute to gravity and negative pressure can cause repulsive gravity. So Gravity is not always an attractive force. Today we observe this effect via the cosmological constant, an overall repulsive gravitational force.

In an earlier discussion on this subject pervect had a nice succinct answer:

: Because the stress-energy tensor for expanding matter is different from the stress-energy tensor of non-expanding matter, you can have compact, dense, expanding objects that are not black holes.

John Baez has this to say:

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/universe.html

Sometimes people find it hard to understand why the Big Bang is not a black hole. After all, the density of matter in the first fraction of a second was much higher than that found in any star, and dense matter is supposed to curve spacetime strongly. At sufficient density there must be matter contained within a region smaller than the Schwarzschild radius for its mass. Nevertheless, the Big Bang manages to avoid being trapped inside a black hole of its own making and paradoxically the space near the singularity is actually flat rather than curving tightly. How can this be?

The short answer is that the Big Bang gets away with it because it is expanding rapidly near the beginning and the rate of expansion is slowing down. Space can be flat even when spacetime is not. Spacetime's curvature can come from the temporal parts of the spacetime metric which measures the deceleration of the expansion of the universe. So the total curvature of spacetime is related to the density of matter, but there is a contribution to curvature from the expansion as well as from any curvature of space. The Schwarzschild solution of the gravitational equations is static and demonstrates the limits placed on a static spherical body before it must collapse to a black hole. The Schwarzschild limit does not apply to rapidly expanding matter.

You can get some additional ideas via Roger Penrose here:

http://epaper.kek.jp/e06/PAPERS/THESPA01.PDF

BEFORE THE BIG BANG: AN OUTRAGEOUS NEW PERSPECTIVE AND ITS IMPLICATIONS FOR PARTICLE PHYSICS

 

[Tanelorn]

Some people get very excited about black holes and speculate about other universes and so on but could it be that they are nothing more than a denser form of matter with sufficient gravitation field that light cannot escape? Nothing more than that?

 

[bapowell]

Some people get very excited about black holes and speculate about other universes and so on but could it be that they are nothing more than a denser form of matter with sufficient gravitation field that light cannot escape? Nothing more than that?

Exactly.

 

[Tanelorn]

Occam strikes again?

 

[Naty1]

Tzikin:..

I haven't read all that much about white holes...so I have no comparisons for the comments
here:

http://en.wikipedia.org/wiki/White_hole

but some might be of interest to you...stuff is ejected from theoretical white holes, if they exist, unlike black holes which swallow stuff...