Could we be at the centre of a black hole?

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thedoc

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Could we be at the centre of a black hole?
« on: 01/07/2014 17:30:01 »
Fred Richardson asked the Naked Scientists:

We live at the centre of a universe whose light radius [our furthest possible observation] is approx 42 billion light years [New Scientist book "Nothing", p9], so what if... we are in the centre of a black hole, comprising 4% of its mass, as we understand the term, the other 96% being black hole glue and goo. So the hologramatic universe idea still works, kind of, except its a concave not a convex event horizon and we are, fittingly and finally, back at the centre of the universe.

Thats Fred with one F if you need to forward this to Sweden, a triple F if it goes to Snowden.  No, but seriously, I'm sure this option must have occurred to scientists before now anyway, but if you can still maybe explain why it is not so I would appreciate it, keep up the good work cobber!

Thanks again for you and your staff's work Chris, its a great show and my 15 year old son and I really enjoy it. I put episodes on in the car on the way to his school some mornings to get the fires started.

What do you think?
« Last Edit: 01/07/2014 17:30:01 by _system »

jeffreyH

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Re: Could we be at the centre of a black hole?
« Reply #1 on: 03/07/2014 01:08:21 »
If the universe was contracting then this might be a reasonable conclusion. As it is expanding this seems highly unlikely. Light would not radiate away in all directions inside a black hole and things would appear very strange indeed.

Bill S

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Re: Could we be at the centre of a black hole?
« Reply #2 on: 03/07/2014 02:36:59 »
Possibly the nearest to a universe inside a black hole is Mazur and Chapline's suggestion of a gravastar.

The name is derived from the words Gravitational Vacuum Star.  So, what is a gravastar?  The simplest (perhaps over-simple) answer to this is that a gravastar is a black hole within which not everything is crushed into an infinitely small space, or even into a super-heavyweight micro-speck.    In a nutshell, a gravastar, according to Mazur and Chapline, is formed when an exceptionally large star nears the end of its life and starts to collapse under its own gravity.  During this process it reaches a critical density at which its matter is converted into energy which gives rise to a fiery boundary layer.  This is the gravastar.  From outside its appearance will be that of an enormous star.  Further collapse will be prevented because, its authors state, the gravity of spacetime inside the boundary will be repulsive.  All cannot remain in a state of equilibrium, however, because some of the energy at the boundary will be converted back into particles of matter.  Such particles that form on the inside of the boundary layer will be accelerated away from one another by the repulsive gravity mentioned above.  This scenario, in which every particle of matter is rushing away from every other particle, bears a striking similarity to the Big Bang scenario.  A major difference, however, is that the original star in this model will have been spinning, (everything in the observable Universe spins, so there is no reason to suppose that this particular star would not do so) and this spin will be conserved in the gravastar.  Mazur and Chapline reason that this spin will manifest itself as vortices forming near the boundary, but being left behind as the boundary moves outward.  These vortices will influence the movement of matter particles, giving rise to the formation of stars and galaxies.  Although the vortices, and subsequent structures to which they give rise, may have been left behind by the spreading boundary, they will not be stationary, but will continue to recede from one another in precisely the manner described for the expanding Universe which we observe around us.  The boundary will be racing away from the vortices nearest to it in the same way that the vortices and galaxies continue to recede from one another.

evan_au

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Re: Could we be at the centre of a black hole?
« Reply #3 on: 03/07/2014 09:28:06 »
The big bang theory suggests that at some point in time, the mass of the entire universe was contained in a volume about the size of a grapefruit.

Since a grapefruit is considerably less than the Schwarzchild radius of our universe, Fred's suggestion is entirely reasonable.

From the viewpoint of anyone outside a black hole, physicists expect that everything would be crushed into a singularity. We don't see this in our universe, so most physicists would like to find a way around this apparent contradiction (or just ignore it).

It is thought that some strange things happen between the dimensions of space and time within a black hole. What a black hole looks like from the viewpoint of an observer already inside the black hole does not have a consensus amongst physicists at this time (and it's not something that we can currently test through experiment).

jeffreyH

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Re: Could we be at the centre of a black hole?
« Reply #4 on: 05/07/2014 09:44:07 »
The Schwarzschild metric fails insides the event horizon. It acts like a singularity at this point. A change in coordinate system can resolve this but why ignore what the original mathematics has shown. We can change the model to fit what we are comfortable with. This is unsatifactory. If the compression of spacetime is so intense at the horizon and length contraction and time dilation affect the surroundings we may be viewing a mathematical equivalent of an optical illusion at the horizon. The horizon becomes the singularity. So no matter how large the initial mass nothing can pass the horizon as it is the singularity. To view this it would be necessary to plot the length contraction during a collapse event down to the point the mass reaches Rs and escape velocity becomes equal to c. AT this point nothing can move outwards. Believing that it can still move inwards might be untrue.
« Last Edit: 05/07/2014 10:09:17 by jeffreyH »

jeffreyH

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Re: Could we be at the centre of a black hole?
« Reply #5 on: 05/07/2014 10:01:28 »
The mathematical result that the Scwarzschild radius of the Plank mass is 2 Planck lengths is significant here. For any mass size, compression to the event horizon reaches a point at which gravitation becomes a purely quantum phenomena.
« Last Edit: 05/07/2014 10:03:38 by jeffreyH »

PmbPhy

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Re: Could we be at the centre of a black hole?
« Reply #6 on: 05/07/2014 10:34:52 »
I don’t know if it’s either true or possible. I tend to think not. However the American Journal of Physics published a paper on the subject.
The observable universe inside a black hole by W.M. Stuckey, Am. J. Phys., 63(9), Sep. (1994). The abstract is online at http://link.aip.org/link/ajpias/v62/i9/p788/s1
Quote
Abstract - A Schwarzschild radial coordinate R is presented for the Friedmann dust-filled cosmology models. It is shown that a worldline of constant Schwarzschild radial coordinate in the dust-filled universe is instantaneously null at $$R_n = 2GM/c^2$$ where M is the Schwarzschild mass inside the sphere at $$R = R_n$$. It is also shown that $$M_p = 3\tauc^3/4G$$, where M p is the proper mass inside $$R = R_n$$ and $$\tau$$ τ is the age of the universe. The $$R_n = 2GM/c^2$$ result in Friedmann dust-filled cosmology is made physically significant by abandoning the cosmological principle and adjoining segments of Friedmann dust to segments of Schwarzschild vacuum. In the resulting cosmology model, the observable universe may lie inside a black or white hole.

jeffreyH

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Re: Could we be at the centre of a black hole?
« Reply #7 on: 05/07/2014 12:17:05 »
I don’t know if it’s either true or possible. I tend to think not. However the American Journal of Physics published a paper on the subject.
The observable universe inside a black hole by W.M. Stuckey, Am. J. Phys., 63(9), Sep. (1994). The abstract is online at http://link.aip.org/link/ajpias/v62/i9/p788/s1
Quote
Abstract - A Schwarzschild radial coordinate R is presented for the Friedmann dust-filled cosmology models. It is shown that a worldline of constant Schwarzschild radial coordinate in the dust-filled universe is instantaneously null at $$R_n = 2GM/c^2$$ where M is the Schwarzschild mass inside the sphere at $$R = R_n$$. It is also shown that $$M_p = 3\tauc^3/4G$$, where M p is the proper mass inside $$R = R_n$$ and $$\tau$$ τ is the age of the universe. The $$R_n = 2GM/c^2$$ result in Friedmann dust-filled cosmology is made physically significant by abandoning the cosmological principle and adjoining segments of Friedmann dust to segments of Schwarzschild vacuum. In the resulting cosmology model, the observable universe may lie inside a black or white hole.

The white hole model intrigues me. Although it seems improbable that the universe is in a white hole as currently described by physics.

PmbPhy

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Re: Could we be at the centre of a black hole?
« Reply #8 on: 05/07/2014 15:09:23 »
Quote from: jeffreyH
The white hole model intrigues me. Although it seems improbable that the universe is in a white hole as currently described by physics.
To me it seems improbable that the entire universe is in a black hole as currently described by physics.

I wish I knew how people came up with ideas like this. If the universe was inside a black hole then light would only come to me from one direction where in reality in comes from all directions.

At the center of a black hole there is a singularity to which everything would be accelerating towards. However when we look out into the universe we see the exact opposite, i.e. that everything is rushing away from us.
« Last Edit: 05/07/2014 15:19:19 by PmbPhy »

jccc

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Re: Could we be at the centre of a black hole?
« Reply #9 on: 05/07/2014 16:05:56 »
Don't blame people. Scientists invented those color holes. People get confused a lot.

PmbPhy

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Re: Could we be at the centre of a black hole?
« Reply #10 on: 05/07/2014 16:44:39 »
Quote from: jccc
Don't blame people. Scientists invented those color holes. People get confused a lot.
Ummm .... scientists are people too ya know.

jccc

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Re: Could we be at the centre of a black hole?
« Reply #11 on: 05/07/2014 16:55:58 »
Quote from: jccc
Don't blame people. Scientists invented those color holes. People get confused a lot.
Ummm .... scientists are people too ya know.
But, they are gifted ya see.

jeffreyH

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Re: Could we be at the centre of a black hole?
« Reply #12 on: 05/07/2014 19:26:42 »
Quote from: jeffreyH
The white hole model intrigues me. Although it seems improbable that the universe is in a white hole as currently described by physics.
To me it seems improbable that the entire universe is in a black hole as currently described by physics.

I wish I knew how people came up with ideas like this. If the universe was inside a black hole then light would only come to me from one direction where in reality in comes from all directions.

At the center of a black hole there is a singularity to which everything would be accelerating towards. However when we look out into the universe we see the exact opposite, i.e. that everything is rushing away from us.

The problem of the light path also applies to white holes. I have thought about this idea before and given it consideration. However, once you really think about all the implications is breaks down quite quickly.

memestreme

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Re: Could we be at the centre of a black hole?
« Reply #13 on: 08/07/2014 12:02:07 »
So, who knows empirically "At the centre of a black hole there is a singularity"?. I agree that there seems to be one at the external skin or event horizon position. But on the other side of this mem[potential]BRANE could not the enormous gravitational energy of a spherical, hollow singularity be sucking into existence, out of the quantum foam, a pocket universe, with us at the centre. And, not being a scientist, could someone explain, from this central vantage point, why light would thus "come from one direction"? Surly that depends on the spacetime geometry evidenced on the underside of said brane.
And I was thinking, that if we were girt by such a BRANE could it's gravitational attraction not go someway to explaining that, currently unknown, 75% of the mass/energy balance of the universe?

jeffreyH

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Re: Could we be at the centre of a black hole?
« Reply #14 on: 09/07/2014 00:23:00 »