Our universe may have emerged from a black hole in a higher-dimensiona

[Tanelorn]

An interesting article for ordinary people but I just wondered if it is science or pseudo science?
It offers an explanation why the Universe has a beginning and has finite age.
To me it suggests many Universes occurring at random, like raindrops falling randomly into an ocean of space time.


http://phys.org/news/2014-08-black-hole-birth-universe.html

Our universe may have emerged from a black hole in a higher-dimensional universe

The cosmos as we know it might be nothing more than a three-dimensional 'mirage' created by a collapsing star in a universe profoundly different than our own

http://www.mnn.com/earth-matters/sp...ck-hole-in-a-higher-dimensional#ixzz39vAvVeP5

 

[marcus]

the arxiv.org preprint
http://arxiv.org/abs/1309.1487
Out of the White Hole: A Holographic Origin for the Big Bang

Razieh Pourhasan, Niayesh Afshordi, Robert B. Mann
(Submitted on 5 Sep 2013 (v1), last revised 22 Sep 2013 (this version, v2))
While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity, whose resolution constitutes the active field of early universe cosmology. Could the big bang be also hidden behind a causal horizon, making us immune to the decadent impacts of a naked singularity? We describe a braneworld description of cosmology with both 4d induced and 5d bulk gravity (otherwise known as Dvali-Gabadadze-Porati, or DGP model), which exhibits this feature: The universe emerges as a spherical 3-brane out of the formation of a 5d Schwarzschild black hole. In particular, we show that a pressure singularity of the holographic fluid, discovered earlier, happens inside the white hole horizon, and thus need not be real or imply any pathology. Furthermore, we outline a novel mechanism through which any thermal atmosphere for the brane, with comoving temperature of 20% of the 5D Planck mass can induce scale-invariant primordial curvature perturbations on the brane, circumventing the need for a separate process (such as cosmic inflation) to explain current cosmological observations. Finally, we note that 5D space-time is asymptotically flat, and thus potentially allows an S-matrix or (after minor modifications) AdS/CFT description of the cosmological big bang.
Comments: 16 pages, 3 figures

I can't offer any evaluation as to how good science it is. I respect Afshordi, very able intelligent guy, seen him over the years. Personally never interested in his research which was more on the stringy side.
Nothing here looks like "pseudo" science. Although has the feel of a wild guess. But there have to be some wild guesses now and then. Most get shot down or forgotten, it comes with the territory.

http://phys.org/news/2013-09-goodbye-big-black-hole-theory.html#inlRlv

 

[Tanelorn]

Thanks Marcus.
Understood that it is only a speculative possibility, until we have some measurements and math!
I remember reading about white holes 40 years ago!

I wonder if this model is also consistent with Sten Odenwald views that space and time are a byproduct of gravity.

 

[marcus]

Can't say! But I noticed another slightly helpful resource: there was a link in the phys.org piece you originally referred to that pointed to a September 2013 article in NATURE NEWS
http://www.nature.com/news/did-a-hyper-black-hole-spawn-the-universe-1.13743

It is short and clearly written. based on interview with Afshordi. It does not go into any great depth but it might help supplement one's understanding. The journalist is named Zeeya Merali---FWIW I think she's pretty good as a science journalist.

Personally this business of braneworlds and 4d stars in a 5d universe. And them having their own 4d stars collapse and form their own hyperspace black holes. This is not my cup of tea.

But scientists have to speculate and consider all manner of wild possibilities. It keeps them young and on their toes. And once in a blue moon there is a substantial payoff.

there are other ways to quantize geometry that don't lead to higher dimension and which do lead to a simple bounce at very high density, so that you simply work back in time and you find our expansion (because it started at very high density) must have been a bounce from a contracting phase of cosmos history. By comparison that is fairly straightforward, no metaphysics just our familiar 3+1 dimensional geometry and its complement of matter, but collapsing and rebounding.

Tame and humdrum compared with Afshordi's hyper-stars collapsing to form hyper-black-holes.

 

[ChrisVer]

Aren't the rebound models unphysical?
check attachment from John A Peacock -Cosmological Physics (2010)
pg 82-83

 

[George Jones]

The open-acccess journal reference is,

http://iopscience.iop.org/1475-7516/2014/04/005,

"Out of the white hole: a holographic origin for the Big Bang", published in the ournal of Cosmology and Astroparticle Physics.

Coauthor Rob Mann is a former chair of the Department of Physics at the University of Waterloo.

Aren't the rebound models unphysical?
check attachment from John A Peacock -Cosmological Physics (2010)
pg 82-83

This well-known result is not relevant for their brane/bulk cosmology.

 

[marcus]

I don't imagine Peacock's result applies to most of the current bounce cosmology papers including those e.g. by Robert Brandenberger and Y-F Cai (who works with him) on matter bounce.

There's been a convergence of researchers on non-singular bounce cosmology including quite well-known folks. Here just as a sample is a June 2014 paper by Brandenberger et al.
http://inspirehep.net/record/1302770?ln=en
Here's a 2012 paper by Brandenberger et al.
http://arxiv.org/abs/1206.2382

I'll also get some pointers to Paul Steinhardt papers on his type of bounce cosmology. Recently it doesn't seem to require extra dimensions, just a bounce in 4d spacetime

 

[marcus]

This might work. It is a short paper, but one can see what previous work they cite:
http://inspirehep.net/record/1267178
Sailing through the big crunch-big bang transition
Itzhak Bars (Southern California U.) , Paul Steinhardt (Princeton U.) , Neil Turok (Perimeter Inst. Theor. Phys.)
Phys.Rev. D89 (2014) 061302
In a recent series of papers, we have shown that theories with scalar fields coupled to gravity (e.g., the standard model) can be lifted to a Weyl-invariant equivalent theory in which it is possible to unambiguously trace the classical cosmological evolution through the transition from big crunch to big bang. The key was identifying a sufficient number of finite, Weyl-invariant conserved quantities to uniquely match the fundamental cosmological degrees of freedom across the transition. In so doing we had to account for the well-known fact that many Weyl-invariant quantities diverge at the crunch and bang. Recently, some authors rediscovered a few of these divergences and concluded based on their existence alone that the theories cannot be geodesically complete. In this note, we show that this conclusion is invalid. Using conserved quantities we explicitly construct the complete set of geodesics and show that they pass continuously through the big crunch-big bang transition.
3 pages, 1 figure.