We are in a Schwarzschild black hole-T or F?

[jmcgrady]

The theory sounds like Humphrey's "White Hole" with the Milky way at the centre of a bound finite spherical universe.

My intuitive (merely intuitive) reaction is that this would NOT be stable and that the dustball would inevitably shrink. therefore collapse would be inevitable.

What if an inherent property of the expanding spacetime hosting the dustball counters the effect of gravity? The expansion of space itself ensures that gravity would not prevail.

 

[jal]

I've been waiting for someone to come up with some math so that we would have something concrete to discuss.

WELL!
Sombody has done the calculations!
Some very interesting results are coming out of this approach.
----------
http://arxiv.org/abs/astro-ph/0606448
Concerning the instantaneous mass and the extent of an expanding universe
Authors: H.J. Fahr, Michael Heyl
(Submitted on 19 Jun 2006 (v1), last revised 4 Dec 2006 (this version, v2))
This radius on the other hand can be shown to be nearly equal to the Schwarzschild radius of the so-defined mass of the universe.
--------

jal

 

[jal]

Since everyone is try to get a better understanding of the universe, I assume that you have extended your search and found the following papers.

http://usparc.ihep.su/spires/find/hep/www?rawcmd=a+Heyl,+Michael

----------------
http://arxiv.org/abs/astro-ph/0606048
About universes with scale-related total masses and their abolition of presently outstanding cosmological problems
Authors: H.J. Fahr, M. Heyl
(Submitted on 2 Jun 2006 (v1), last revised 4 Dec 2006 (this version, v2))
Cosmological consequences of a strictly valid total energy conservation for the whole universe are investigated in this paper.
… one can also conclude that for some reason about 70% of the total energy permanently remains in the vacuum during the expansion of the universe - representing itself as vacuum energy - while about 30% manifest itself as matter. This ratio must be constant during the whole evolution of the universe because
both, vacuum energy and matter density, follow the assumed R^−2u scaling.
------------
Cosmic vacuum energy decay and creation of cosmic matter.
Hans-Jörg Fahr, Michael Heyl
Argelander Institute for Astronomy, University of Bonn, 53121, Bonn, Germany, hfahr@astro.uni-bonn.de.
Source: Naturwissenschaften, Volume 94, Number 9, September 2007 , pp. 709-724(16)
Publisher: Springer
Abstract:
In the more recent literature on cosmological evolutions of the universe, the cosmic vacuum energy has become a nonrenouncable ingredient. The cosmological constant Λ, first invented by Einstein, but later also rejected by him, presently experiences an astonishing revival. Interestingly enough, it acts like a constant vacuum energy density would also do. Namely, it has an accelerating action on cosmic dynamics, without which, as it appears, presently obtained cosmological data cannot be conciliated with theory. As we are going to show in this review, however, the concept of a constant vacuum energy density is unsatisfactory for very basic reasons because it would claim for a physical reality that acts upon spacetime and matter dynamics without itself being acted upon by spacetime or matter.
---------------
http://arxiv.org/abs/0710.0269v1
Einstein universes stabilized
Authors: Erhard Scholz
(Submitted on 1 Oct 2007)
The hypothesis that gravitational self-binding energy may be the source for the vacuum energy term of cosmology is studied in a Newtonian Ansatz. For spherical spaces the attractive force of gravitation and the negative pressure of the vacuum energy term form a self stabilizing system under very reasonable restrictions for the parameters, among them a characteristic coefficient \beta of self energy. In the Weyl geometric approach to cosmological redshift, Einstein-Weyl universes with observational restrictions of the curvature parameters are dynamically stable, if \beta is about 40 % smaller than in the exact Newton Ansatz or if the space geometry is elliptical.
========
jal

 

[jal]

I would presume that the Mach's Principle was understood by : R. G. Vishwakarma, and Parampreet Singh when they wrote the following paper and equated the brane to the Schwarzschild horizon and proposed various answers.
http://lanl.arxiv.org/abs/astro-ph/0211285v3
Can brane cosmology with a vanishing \Lambda explain the observations?
Authors: R. G. Vishwakarma (IUCAA), Parampreet Singh (IUCAA)
(Submitted on 13 Nov 2002 (v1), last revised 21 Mar 2003 (this version, v3))

In brane cosmology, the homogeneous, isotropic RobertsonWalker (RW) universe can be envisioned as a hyper surface embedded in the Schwarzschild anti-deSitter (AdS) bulk spacetime.

The small fluctuations (anisotropies) in the temperature of CMB offer a glimpse of the epoch in the early universe when photons decoupled from the cosmic plasma at zdec = 1100. Before this epoch, matter and radiation were tightly coupled and behaved like a single fluid. (insert comment – a quark-gluon liquid).
At z = 1100, the temperature dropped sufficiently to let the protons capture electrons to form neutral hydrogen and other light elements (recombination). . (insert comment – prior to z = 1100, Hydrogen was a solid then a liquid then a gas).
As the electrons, which had trapped photons, disappeared reducing the opacity for Thomson scattering, the photons decoupled (last scattered) from matter.

The initial fluctuations in the tightly coupled baryon-photon plasma oscillate at the speed of sound driven by gravity, inertia of baryons and pressure from photons. This continues until the recombination epoch. Physically these oscillations represent the hot and cold spots on the fluid generated by compression and rarefaction by a standing sound or acoustic wave. Thus the wave which has a density maximum at the time of last scattering, corresponds to a peak in the power spectrum.
The locations of the peaks are set by the acoustic scale ℓA, which can be interpreted as the angle subtended by the sound horizon at the last scattering surface. This angle (say, θA) is given by the ratio of sound horizon to the distance (angular diameter distance) of the last scattering surface:

 

[jal]

A politically correct was of using a black hole horizon = "future event horizon".

http://xxx.lanl.gov/abs/astro-ph/0601598
Dynamical dark energy with a constant vacuum energy density
Authors: B. Guberina, R. Horvat, H. Nikolic
(Submitted on 26 Jan 2006 (v1), last revised 20 Mar 2006 (this version, v2))
A symmetry principle of gravitational holography [1] serves as a window to a complete
theory of quantum gravity. According to that principle, the description of a physical system shows equivalence between a theory having the gravitational field quantized and a theory defined on the boundary encompassing a system whose dimension is lower by one.

We start with the fact that in an ever accelerating universe there always exists a future event horizon. Thus, analogously to the black-hole horizon, it can be attributed some thermodynamical quantities, like entropy and temperature.

The GSL states that the entropy of the event horizon plus the entropy of matter and radiation in the volume within the horizon cannot decrease in time.
======
I hope that I've presented enough info for even the hardest skeptic.
Jal

 

[jal]

The following approach is relevant to this thread.
http://arxiv.org/abs/0804.1771
The cosmic variance of Omega
Authors: T. P. Waterhouse, J. P. Zibin
(Submitted on 10 Apr 2008)

 

[jal]

http://arxiv.org/abs/hep-th/0603133
Naturalness of the Vacuum Energy in Holographic Theories
Authors: Csaba Balazs, Istvan Szapudi
(Submitted on 17 Mar 2006)
Based on the cosmic holographic conjecture of Fischler and Susskind, we point out that the average energy density of the universe is bound from above by its entropy limit. Since Friedmann's equation saturates this relation, the measured value of the cosmological energy density is completely natural in the framework of holographic thermodynamics: vacuum energy density fills the available quantum degrees of freedom allowed by the holographic bound. This is in strong contrast with traditional quantum field theories where, since no similar bound applies, the natural value of the vacuum energy is expected to be 123 orders of magnitude higher than the holographic value. Based on our simple calculation, holographic thermodynamics, and consequently any future holographic quantum (gravity) theory, resolves the vacuum energy puzzle.

 

[foolosophy]

If we are in fact living in a black hole then te BLACK HOLES we are describing within our own reality arent really balck holes but something else entirely.

You have set up a convoluted argument - close to a mathematical paradox by posing the question in that way.

And in any case there is no way of knowing.

A few points though come to mind -

If we are indeed living in a black hole, then why is it expanding?

Why are we proposing a BIG BANG cosmological model?

Why arent we detecting any material or energy that should be entering our little black hole via the event horizon?

What exactly is the Cosmic Backgound radiation then?

 

[jal]

My quest started by a simple question, “How is the universe made and how does it works?”
As you can see in my blog, many have asked this question and there are many different approaches to try to get an answer.
I get my pleasure from seeking the answers.
I have not found the answer but I’m still looking.
jal

 

[foolosophy]

The Socratic Method

The Socratic method is over 2500 years old and involves the gaining of wisdom and knowledge via the asking of questions - its still a fundamental basis for education and teaching throughout the world today.

 

[foolosophy]

confusing the location of the event horizon with the actual singularity itself is a common miss interpretation of what a Black hole is.

 

[jmcgrady]

...How can we tell we arent in a BH? A LARGE black hole containing thousands of galaxies.

We if we were there would be a direction towards the collapse point, and in that direction galaxies would be redshifted because they would be accelerating faster, ahead of us, and in the reverse direction (behind us) galaxies would also be redshifted because we would be accelerating faster and escaping from them! And in the plane of direction which are abeam of us, sideways from that collapse direction (to port and starbord so to speak) galaxies would be BLUE shifted, cause we are all getting closer to each other as we approach the collapse point.

What if the Milky Way was at the centre of the BH? Say the universe is a bounded sphere. And that there is a greater density of galaxies near the centre - so much so that the schwarzschild BH criteria are met some distance from the centre such that the radius is less than 13.7 billion light years but greater than X billion light years. Would this explain why we see most galaxies as red shifted?

 

[jal]

Leonid V. Verozub, will be making a presentation at the NEB-XIII Poster Session http://www.astro.auth.gr/~neb-13/program-posters.pdf
http://www.astro.auth.gr/~neb-13/programme.html
Here is his latest paper.
http://arxiv.org/abs/0805.0313v1
On accelerated Universe expansion
Authors: Leonid V. Verozub
(Submitted on 2 May 2008)
Abstract: It is shown that observed peculiarities of the Universe expansion are an inevitable consequence of the gravitational force properties following from gauge-invariant gravitation equations considered in detail in an author's paper in Annalen der Physik, v.17, 28 (2008).

 

[jonmtkisco]

Hi Jal,

Do you know if it's possible to get the Verozub paper from Ann. Phys. (Berlin) 2008? Apparently that's where he describes his underlying equations.

His solution for gravitational acceleration changing sign at a large distance and then declining to zero at infinity sounds like a good conceptual match for a kinematic-GR model. Then gravity can be the source of all kinematics in the universe.

At least it's worth understanding in more detail.

Jon

 

[jal]

I can only access his papers by "clicking" on his name. I did not check out the rest of his papers. Maybe there is something there.
jal

 

[jonmtkisco]

HI jal,

It turns out he has a dozen or so papers on arXiv, all playing around with the same idea. His math is pretty inaccessible.

Jon

 

[yuiop]

...from post#40...

and around big bang time, stuff was WAY denser than Schwarzschild requires, so why didnt the universe collapse then and there? Because it was expanding so fast.
...

Hi Marcus,

I normally hang around in the relativity forum (but I am by no means a relativity expert) and while playing around with Schwarzschild solutions I made a discovery that I think is very relevant to this thread and may provide an alternative answer to the question you pose here.

The equation for coordinate acceleration in the exterior Schwarzschild solution is:

a '=\frac{GM}{R^2}\left(1-\frac{R_s}{R}\right)

When R is greater than the Schwarzschild radius the gravitational acceleration is positive towards the mass as you would expect. When R is less than the Schwarzschild radius the gravityational acceleration is negative and directed outwards towards the event horizon. if for example all the mass of the universe was originally confined to radius of R=Rs/10 then the outward acceleration is -900 GM/Rs^2. If the mass was confined to R=Rs/1,000 then the outward acceleration is -999,000,000 GM/Rs^2. Obviously, the outward gravitational acceleration gets considerably larger as original density increases.

Now if we look at the coordinate velocity of photon falling from infinity the equation is:

c '= c\left(1-\frac{R_s }{R}\right)

and for R>Rs the coordinate velocity is always less than c, the velocity of light at infinity. Below the Schwarzschild radius the coordinate velocity of light get larger than c and is negative. This value for R<Rs is the speed of light falling from the centre outwards towards the event horizon. So for a universe with an extreme initial density photons (and particles with mass) move outwards towards the Schwarzschild radius at velocities much greater than c. In other words the outward expansion would very rapid until the universe reached the size of its own Schwarzschild radius. In fact the expansion would be arbitarily high and only limited by the initial density. The greater the initial density the greater the initial expansion. This would be very like the inflation that is thought to have occurred early in the history of the universe. For falling particles the coordinate velocity is given by:

v &#039; = c\sqrt{{Rs \over R}} \left(1-\frac{R_s}{R} \right)

One possible objection to this idea is that the coordinate velocity of the outward moving particles becomes zero at the Schwarzschild radius bring everything to a stop. I think this issue can be resolved by considering a universe with an initially flat spacetime. The rapid expansion of the particles within the Schwarzschild volume sends a gravitational shock wave that ripples outwards. Gravity waves have no difficulty passing event horizons and carry energy away with them. The loss of energy from the Schwarzschild volume reduces the Schwarzschild radius, releasing the particles trapped at the event horizon. The process is self destructive and the event horizon dissappears.

If dark energy is ignored this model would basically oscillate, with the universe expanding and collapsing to point and then expanding again. With dark energy it may never collapse.

I came to this conclusion while investigating the interior Schwarzschild solution that enables you examine what happens to a black hole as it forms and found that normal stable black holes do not have a singularity of infinite density at the centre but are a thin shell of matter just outside the event horizon.


For more equations and background on these ideas, see these threads:

https://www.physicsforums.com/showthread.php?t=238839&page=2 post #19 onwards.

https://www.physicsforums.com/showpost.php?p=1767802&postcount=17

https://www.physicsforums.com/showthread.php?t=223730&page=2 post#19

I hope these ideas are of interest. The nice thing about them is that they basically fall straight out of the Schwarzschild solutions. I am not saying dark energy does not exist or that the Schwarzschild solutions might have to be modified a bit to allow for expanding spacetime, but I am saying that that even without those things the Schwarzschild equations do not imply the universe would be trapped in a black hole even when there technically enough mass within a given radius to be a black hole. In fact, examination of the solutions show the universe would be very different if we were inside a black hole.

 

[yuiop]

One possible objection to this idea is that the coordinate velocity of the outward moving particles becomes zero at the Schwarzschild radius bring everything to a stop. I think this issue can be resolved by considering a universe with an initially flat spacetime. The rapid expansion of the particles within the Schwarzschild volume sends a gravitational shock wave that ripples outwards. Gravity waves have no difficulty passing event horizons and carry energy away with them. The loss of energy from the Schwarzschild volume reduces the Schwarzschild radius, releasing the particles trapped at the event horizon. The process is self destructive and the event horizon dissappears.

I just found a counter argument to my above statement. Damn!
http://en.wikipedia.org/wiki/Birkhoff's_theorem_(relativity )

Birkhoff's theorem states a pulsating spherical mass can not give off gravitational waves. That seems reasonable as the gravitaional filed of a sperical object always looks like a point source outside the mass of the body.

There are however any number of potential ways that the mass trapped in a shell at the Schwarzschild radius can escape. The loss of a single atom or photon by Hawking radiation or quantum tunelling would start the destruction of the event horizon. This is even more likely as there is no CMB radiation adding to the mass/energy of the Schwarzschild mass at this epoch. The other method is to observe that the escape velocity at the event horizon is c and that during the inflation period the velocities of exceed c as explained in my last post.

So for those who cherish the notion that if the universe is expanding, that it must have been smaller and denser at some time in the past, GR can cope with that. For those that don't like that notion, you can take comfort with thought of a universe that started infinite in volume and mass and then continued expanding.