Expansion, turnaround, contraction and bounce. Those are the four components of a new model of the universe created by researchers at the University of North Carolina at Chapel Hill. Their work offers an alternative to the Big Bang theories in the marketplace and sets up a cyclical progression in which an infinite number of independent universes emerge from what’s left of matter just before the end of time.

Tough going, this. But think of the universe’s vast expansion pushing everything progressively further out until all matter disintegrates. This is the turnaround point, and it is here that each fragmented ‘patch’ of what had been matter collapses and contracts. “We discuss contraction which occurs with a very much smaller universe than in expansion,” write the researchers, “and with almost vanishing entropy because it is assumed empty of dust, matter and black holes.”

The key is that this collapse occurs individually, so that rather than causing the Big Bang to run in reverse, each patch becomes an independent universe that reinflates. Hence the ‘bounce.’

Lauris Baum and Paul Frampton, co-authors of the paper on this work, take aim at the key problem: entropy. The idea of an oscillating universe isn’t new, but the second law of thermodynamics says that entropy should increase from one cycle to the next. That leads straight back to an initial singularity and seems to rule out the idea of an infinitely cycling universe. But the discovery of dark energy and its possibiities in the cosmic mix inspired this new look at oscillations and their uses.

And the researchers get around the entropy problem by assuming that at the time of turnaround, any remaining entropy is in patches that are too remote for interaction. From the paper:

“The second law of thermodynamics continues to obtain for other causal patches, each with practically vanishing entropy at turnaround, but these are permanently removed from our universe, contracting instead into separate universes.”

Thus a kind of multiverse different from previous theories:

“…our proposal of deﬂation naturally leads to a multiverse picture, somewhat reminiscent of that predicted in eternal inﬂation, though here the proliferation of universes must be inﬁnite and originates at the opposite end of a cyclic cosmology, at its maximum rather than at its minimum size.”

The paper is Baum and Frampton, “Turnaround in Cyclic Cosmology,” slated to appear in *Physical Review Letters* and available as a preprint. I point you to the latter for the authors’ analysis of dark energy’s ‘equation of state’ (describing its pressure and density), which goes far beyond my mathematical powers but is vital to achieving the needed outcome. Thanks to Adam Rosalky and Larry Klaes for the pointer to this paper.

Comments on this entry are closed.

Hi Paul

It’s not really a bounce model in the old sense of all the matter “missing” the singularity at the Big Crunch and starting a new Big Bang. Instead all the old Universe’s matter is spread really, really thin and new Big Bangs spring forth from the old vacuum. What’s returned to “cyclically” is the initial vacuum state – assumed to be ultra-low entropy.

Adam

Cyclic Universe and Infinite Past

Authors: Paul H. Frampton

(Submitted on 18 May 2007)

Abstract: We address two questions about the past for infinitely cyclic cosmology. The first is whether it can contain an infinite length null geodesic into the past in view of the Borde-Guth-Vilenkin (BGV) “no-go” theorem, The second is whether, given that a small fraction of spawned universes fail to cycle, there is an adequate probability for a successful universe after an infinite time. We give positive answers to both questions then show that in infinite cyclicity the total number of universes has always been infinite, given an appropriate definition of time $t = – \infty$.

Comments:

7 pages

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0705.2730v1 [astro-ph]

Submission history

From: Paul Frampton [view email]

[v1] Fri, 18 May 2007 16:22:52 GMT (6kb)

http://arxiv.org/abs/0705.2730

Physics in the multiverse: an introductory review

Authors: Aurelien Barrau

(Submitted on 28 Nov 2007)

Abstract: This brief note, written for non-specialists, aims at drawing an introductive overview of the multiverse issue.

Comments: 6 pages

Subjects: Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics – Phenomenology (hep-ph); High Energy Physics – Theory (hep-th); Quantum Physics (quant-ph)

Journal reference: CERN Courier, vol. 47, issue 10 (2007) pp. 13-17

Cite as: arXiv:0711.4460v1 [astro-ph]

Submission history

From: Aurelien Barrau [view email]

[v1] Wed, 28 Nov 2007 10:30:24 GMT (8kb)

http://arxiv.org/abs/0711.4460

Evidence for the Multiverse in the Standard Model and Beyond

Authors: Lawrence J. Hall, Yasunori Nomura

(Submitted on 17 Dec 2007)

Abstract: In any theory it is unnatural if the observed parameters lie very close to special values that determine the existence of complex structures necessary for observers. A naturalness probability, P, is introduced to numerically evaluate the unnaturalness. If P is small in all known theories, there is an observer naturalness problem. In addition to the well-known case of the cosmological constant, we argue that nuclear stability and electroweak symmetry breaking (EWSB) represent significant observer naturalness problems. The naturalness probability associated with nuclear stability is conservatively estimated as P_nuc less than 10^{-(3-2)}, and for simple EWSB theories P_EWSB less than 10^{-(2-1)}. This pattern of unnaturalness in three different arenas, cosmology, nuclear physics, and EWSB, provides evidence for the multiverse. In the nuclear case the problem is largely solved even with a flat multiverse distribution, and with nontrivial distributions it is possible to understand both the proximity to neutron stability and the values of m_e and m_d – m_u in terms of the electromagnetic contribution to the proton mass. It is reasonable that multiverse distributions are strong functions of Lagrangian parameters due to their dependence on various factors. In any EWSB theory, strongly varying distributions typically lead to a little or large hierarchy, and in certain multiverses the size of the little hierarchy is enhanced by a loop factor. Since the correct theory of EWSB is unknown, our estimate for P_EWSB is theoretical. The LHC will determine P_EWSB more robustly, which may remove or strengthen the observer naturalness problem of EWSB. For each of the three arenas, the discovery of a natural theory would eliminate the evidence for the multiverse; but in the absence of such a theory, the multiverse provides a provisional understanding of the data.

Comments: 79 pages, 23 figures

Subjects: High Energy Physics – Phenomenology (hep-ph); Astrophysics (astro-ph); High Energy Physics – Theory (hep-th)

Report number: UCB-PTH-07/26

Cite as: arXiv:0712.2454v1 [hep-ph]

Submission history

From: Yasunori Nomura [view email]

[v1] Mon, 17 Dec 2007 14:43:08 GMT (202kb)

http://arxiv.org/abs/0712.2454

Prediction and explanation in the multiverse

Authors: Jaume Garriga, Alexander Vilenkin

(Submitted on 16 Nov 2007 (v1), last revised 17 Jan 2008 (this version, v3))

Abstract: Probabilities in the multiverse can be calculated by assuming that we are typical representatives in a given reference class. But is this class well defined? What should be included in the ensemble in which we are supposed to be typical? There is a widespread belief that this question is inherently vague, and that there are various possible choices for the types of reference objects which should be counted in. Here we argue that the “ideal” reference class (for the purpose of making predictions) can be defined unambiguously in a rather precise way, as the set of all observers with identical information content. When the observers in a given class perform an experiment, the class branches into subclasses who learn different information from the outcome of that experiment. The probabilities for the different outcomes are defined as the relative numbers of observers in each subclass. For practical purposes, wider reference classes can be used, where we trace over all information which is uncorrelated to the outcome of the experiment, or whose correlation with it is beyond our current understanding.

We argue that, once we have gathered all practically available evidence, the optimal strategy for making predictions is to consider ourselves typical in any reference class we belong to, unless we have evidence to the contrary. In the latter case, the class must be correspondingly narrowed.

Comments: Minor clarifications added

Subjects: High Energy Physics – Theory (hep-th); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc)

Cite as: arXiv:0711.2559v3 [hep-th]

Submission history

From: Jaume Garriga [view email]

[v1] Fri, 16 Nov 2007 05:27:57 GMT (13kb)

[v2] Thu, 22 Nov 2007 05:28:38 GMT (13kb)

[v3] Thu, 17 Jan 2008 16:51:21 GMT (14kb)

http://arxiv.org/abs/0711.2559

Cosmology and Cosmogony in a Cyclic Universe

Authors: Jayant V. Narlikar, Geoffrey Burbidge, R.G. Vishwakarma

(Submitted on 18 Jan 2008)

Abstract: In this paper we discuss the properties of the quasi-steady state cosmological model (QSSC) developed in 1993 in its role as a cyclic model of the universe driven by a negative energy scalar field. We discuss the origin of such a scalar field in the primary creation process first described by F. Hoyle and J. V. Narlikar forty years ago. It is shown that the creation processes which takes place in the nuclei of galaxies are closely linked to the high energy and explosive phenomena, which are commonly observed in galaxies at all redshifts.

The cyclic nature of the universe provides a natural link between the places of origin of the microwave background radiation (arising in hydrogen burning in stars), and the origin of the lightest nuclei (H, D, He$^3$ and He$^4$). It also allows us to relate the large scale cyclic properties of the universe to events taking place in the nuclei of galaxies. Observational evidence shows that ejection of matter and energy from these centers in the form of compact objects, gas and relativistic particles is responsible for the population of quasi-stellar objects (QSOs) and gamma-ray burst sources in the universe.

In the later parts of the paper we briefly discuss the major unsolved problems of this integrated cosmological and cosmogonical scheme. These are the understanding of the origin of the intrinsic redshifts, and the periodicities in the redshift distribution of the QSOs.

Comments: 51 pages including 1 figure

Subjects: Astrophysics (astro-ph)

Journal reference: J. Astrophys. Astron. (2007) vol. 28, p. 67-99

Cite as: arXiv:0801.2965v1 [astro-ph]

Submission history

From: R. G. Vishwakarma [view email]

[v1] Fri, 18 Jan 2008 20:38:18 GMT (122kb)

http://arxiv.org/abs/0801.2965

The Hagedorn Soup and an Emergent Cyclic Universe

Authors: Tirthabir Biswas

(Submitted on 8 Jan 2008)

Abstract: One of the problems of constructing a successful cyclic universe scenario is that it has to incorporate the second law of thermodynamics. This leads to Tolman’s ever shrinking cycles which eventually vanish at a finite proper time in the past.

In this paper we construct a theoretically consistent (ghost-free) non-singular toy model where as the cycles shrink in the past they also spend more and more time in the Hagedorn phase where all the string states are in thermal equilibrium and entropy is conserved. Thus in such a scenario the entropy asymptotes to a finite non-zero constant in the infinite past. The universe “emerges” from a small (string size) geodesically complete quasi-periodic space-time. This paradigm also naturally addresses some of the classic puzzles of Big Bang cosmology, such as the largeness, horizon and flatness problems.

Comments: 15 pages, 1 figure

Subjects: High Energy Physics – Theory (hep-th); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics – Phenomenology (hep-ph)

Report number: IGC-08/1-2

Cite as: arXiv:0801.1315v1 [hep-th]

Submission history

From: Tirthabir Biswas [view email]

[v1] Tue, 8 Jan 2008 20:31:09 GMT (28kb)

http://arxiv.org/abs/0801.1315

Probing the creatable character of perturbed Friedmann-Robertson-Walker universes

Authors: Ramon Lapiedra, Diego Sáez

(Submitted on 5 Apr 2008)

Abstract: We discuss whether some perturbed Friedmann-Robertson-Walker (FRW) universes could be creatable, i. e., could have vanishing energy, linear momentum and angular momentum, as it could be expectable if the Universe arose as a quantum fluctuation.

On account of previous results, the background is assumed to be either closed (with very small curvature) or flat. In the first case, fully arbitrary linear perturbations are considered; whereas in the flat case, it is assumed the existence of: (i) inflationary scalar perturbations, that is to say, Gaussian adiabatic scalar perturbations having an spectrum close to the Harrison-Zel’dovich one, and (ii) arbitrary tensor perturbations.

We conclude that, any closed perturbed universe is creatable, and also that, irrespective of the spectrum and properties of the inflationary gravitational waves, perturbed flat FRW universes with standard inflation are not creatable. Some considerations on pre-inflationary scalar perturbations are also presented. The creatable character of perturbed FRW universes is studied, for the first time, in this paper.

Comments: 22 pages, accepted for publication in Phys. Rev. D

Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics (astro-ph)

Cite as: arXiv:0804.0861v1 [gr-qc]

Submission history

From: Diego S\’aez [view email]

[v1] Sat, 5 Apr 2008 16:08:12 GMT (19kb)

http://arxiv.org/abs/0804.0861

Big Bangs by the Bajillion?

A Conference on the Multiverse

Three different trends in physics each suggest that our universe is just one of many.

September 18, 2008 by Dan Falk

——————————————————————————–

We usually think of the universe as being “everything there is.” But many astronomers and physicists now suspect that the universe we observe is just a small part of an unbelievably larger and richer cosmic structure, often called the “multiverse.” This mind-bending notion – that our universe may be just one of many, perhaps an infinite number, of real, physical universes – was front and center at a three-day conference entitled “A Debate in Cosmology — The Multiverse,” held at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, earlier this month.

Physicist Paul Davies points out that with cosmic inflation, things get fantastically big very fast. (The conference was in Canada, so a hockey stick was the pointer of choice.) Dan Falk

The multiverse idea is not new. Physicists have been toying with it ever since Hugh Everett III came up with the “many worlds” interpretation of quantum mechanics back in the 1950s. It took on new life after 1980, when the inflationary-universe theory of the Big Bang’s first moments began to suggest that our Big Bang was not a unique event but just a tiny bit of a much larger, ongoing process.

The multiverse idea has had yet another surge of interest in recent years, as a result of a newer idea: string theory. Developed as a possible “theory of everything” that would unite quantum mechanics and gravity, string theory, physicists hoped, would provide a unique description of the universe and why the laws of nature are what they are. Instead, according to some theorists, it lays out a picture of not a single universe but rather a broader “landscape” in which the laws of physics vary from one region to another. It may be that only a small fraction of these regions have conditions allowing any kind of complex matter to exist, and hence intelligent life.

Full article and photos here:

http://www.skyandtelescope.com/news/home/28528759.html

Did Our Cosmos Exist Before The Big Bang?

When researchers ran a computer simulation of the universe rewinding towards the big bang, they made an unexpected discovery. At first, the universe started becoming smaller and denser as the galaxies converged, but then instead of becoming infinitely dense at the big bang, the universe bounced and started expanding again. So is our universe recycled from an older cosmos?

Full article here:

http://www.newscientist.com/article/mg20026861.500-did-our-cosmos-exist-before-the-big-bang.html

Universe has more entropy than thought

ScienceNews Oct. 2, 2009

A new calculation of the entropy of the universe by Australian physicists indicates that the collective entropy of all the supermassive black holes at the centers of galaxies is 10^104, about 100 times higher than previously calculated, suggesting that the universe is slightly further along on its gradual journey to heat death….

http://www.kurzweilai.net/email/newsRedirect.html?newsID=11233&m=25748

Hi,

I think a possible oscillating universe could be better understood and believed if supported by what I think about:

http://vixra.org/pdf/1204.0076v1.pdf

My naive paper is against the (unfound) dark matter, so in agreement with what just observed by astrophysicists in Chile.

Thank you.

Leonardo Rubino.

leonrubino@yahoo.it