Among the crushing throng of physics enthusiasts who gathered this week for a lecture by Sir Roger Penrose, who is to the University of Oxford what Stephen Hawking is to Cambridge, the very mention of the Large Hadron Collider in Switzerland elicited a resounding throaty chuckle. Everyone knew that when the world's biggest particle accelerator was switched on last month, its computers were promptly hacked and its superconducting magnets accidentally melted. And provided one is sceptical of all the media reports about how this "Big Bang machine" might create an apocalyptic black hole somewhere beneath Geneva, this is all pretty hilarious, just a few broken eggs for the omelette of discovery.

Sir Roger Penrose: Before the Big Bang: Is There Evidence For Something And If So, What? October 1, 2008 at 7:00 pm

There is now a great deal of evidence confirming the existence of a very hot and dense early stage of the universe. Much of this data comes from a detailed study of the cosmic microwave background (CMB) - radiation from the early universe that was most recently measured by NASA's WMAP satellite. But the information presents new puzzles for scientists. One of the most blatant examples is an apparent paradox related to the second law of thermodynamics. Although some have argued that the hypothesis of inflationary cosmology solves some of the puzzles, profound issues remain. In this talk, Professor Penrose will describe a very different proposal, one that suggests a succession of universes prior to our own. He will also present a recent analysis of the CMB data that has a profound bearing on these issues.

Before the universe's theoretical beginning Respected scientists have proposed a flock of theories to describe what might have happened before the birth of our familiar universe of space and time. The concepts have fanciful names such as "the big bounce," "the multiverse," "the cyclic theory," "parallel worlds," even "soap bubbles." Some propose the existence of multiple universes. Others hold that there's one universe that recycles itself endlessly, rather as Buddhists believe.

Title: The Spatially Closed Universe Authors: Chan-Gyung Park (Version v3)

The general world model for homogeneous and isotropic universe has been proposed. For this purpose, we introduce a global and fiducial system of reference (world reference frame) constructed on a 5-dimensional space-time that is embedding the universe, and define the line element as the separation between two neighbouring events that are distinct in space and time, as viewed in the world reference frame. The effect of cosmic expansion on the measurement of physical distance has been correctly included in the new metric, which differs from the Friedmann-Robertson-Walker metric where the spatial separation is measured for events on the hypersurface at a constant time while the temporal separation is measured for events at different time epochs. The Einstein's field equations with the new metric imply that closed, flat, and open universes are filled with positive, zero, and negative energy, respectively. We have demonstrated that the flat universe is empty and stationary, equivalent to the Minkowski space-time, and that the universe with positive energy density is always spatially closed and finite. In the closed universe, the proper time of a comoving observer does not elapse uniformly as judged in the world reference frame, in which both cosmic expansion and time-varying light speeds cannot exceed the limiting speed of the special relativity. We have also reconstructed cosmic evolution histories of the closed world models that are consistent with recent astronomical observations, and derived useful formulas such as energy-momentum relation of particles, redshift, total energy in the universe, cosmic distance and time scales, and so forth. It has also been shown that the inflation with positive acceleration at the earliest epoch is improbable.

For decades, physicists have accepted the notion that the universe started with the Big Bang, an explosive event at the literal beginning of time. Now, computational physicist Neil Turok is challenging that model -- and some scientists are taking him seriously. According to Turok, who teaches at Cambridge University, the Big Bang represents just one stage in an infinitely repeated cycle of universal expansion and contraction. Turok theorises that neither time nor the universe has a beginning or end.

Title: The Phantom Bounce: A New Proposal for an Oscillating Cosmology Authors: Katherine Freese, Matthew G. Brown, William H. Kinney

An oscillating universe cycles through a series of expansions and contractions. We propose a model in which ``phantom'' energy with a supernegative pressure (p < - ho) grows rapidly and dominates the late-time expanding phase. The universe's energy density is then so large that the effects of quantum gravity are important at both the beginning and the end of each expansion (or contraction). The bounce can be caused by high energy modifications to the Friedmann equation governing the expansion of the universe, which make the cosmology nonsingular. The classic black hole overproduction of oscillating universes is resolved due to their destruction by the phantom energy.

Title: Bouncing Cosmologies Authors: M. Novello, S.E.Perez Bergliaffa

We review the general features of nonsingular universes i.e. those that go from an era of accelerated collapse to an expanding era without displaying a singularity) as well as cyclic universes. We discuss the mechanisms behind the bounce, and analyse examples of solutions that implement these mechanisms. Observational consequences of such regular cosmologies are also considered, with emphasis in the behaviour of the perturbations.

Title: From Big Crunch to Big Bang with AdS/CFT Authors: Neil Turok, Ben Craps, Thomas Hertog (Version v3)

The AdS/CFT correspondence is used to describe five-dimensional cosmology with a big crunch singularity in terms of super-Yang-Mills theory on R times S^3 deformed by a potential which is unbounded below. Classically, a Higgs field in the dual theory rolls to infinity in finite time. But since the S^3 is finite, the unstable mode spreads quantum mechanically and the singularity is resolved when self-adjoint boundary conditions are imposed at infinity. Asymptotic freedom of the coupling governing the instability gives us computational control and the quantum spreading provides a UV cutoff on particle creation. The bulk interpretation of our result is a quantum transition from a big crunch to a big bang. An intriguing consequence of the near scale-invariance of the dual theory is that a nearly scale-invariant spectrum of stress-energy perturbations is automatically generated in the boundary theory. We comment on implications for more realistic cosmologies.

According to data taken from NASAs WMAP and research performed by University of Illinois researchers, the universe may not have started out with a theory involving traditional inflation. Cosmologist and professor Benjamin D. Wandelt and graduate student Amit Yadav of the University of Illinois, Urbana-Champaign (Department of Physics and Astronomy), used data from NASAs Wilkinson Microwave Anisotropy Probe (WMAP) satellite to measure small temperature fluctuations in the cosmic microwave background (CMB) radiation that still is present today all throughout the universe.