A new cosmological model demonstrates the universe can endlessly expand and contract, providing a rival to Big Bang theories and solving a thorny modern physics problem, according to University of North Carolina at Chapel Hill physicists.
The cyclic model proposed by Dr. Paul Frampton, Louis J. Rubin Jr. distinguished professor of physics in UNC's College of Arts and Sciences, and co-author Lauris Baum, a UNC graduate student in physics, has four key parts: expansion, turnaround, contraction and bounce.

During expansion, dark energy -- the unknown force causing the universe to expand at an accelerating rate -- pushes and pushes until all matter fragments into patches so far apart that nothing can bridge the gaps. Everything from black holes to atoms disintegrates. This point, just a fraction of a second before the end of time, is the turnaround.

At the turnaround, each fragmented patch collapses and contracts individually instead of pulling back together in a reversal of the Big Bang. The patches become an infinite number of independent universes that contract and then bounce outward again, reinflating in a manner similar to the Big Bang. One patch becomes our universe.

"This cycle happens an infinite number of times, thus eliminating any start or end of time," Frampton said. "There is no Big Bang."

An article describing the model is available on the arXiv.org e-print archive and will appear in an upcoming issue of Physical Review Letters. The work was supported in part by a U.S. Department of Energy grant.

Cosmologists first offered an oscillating universe model, with no beginning or end, as a Big Bang alternative in the 1930s. The idea was abandoned because the oscillations could not be reconciled with the rules of physics, including the second law of thermodynamics, Frampton said.

The second law says entropy (a measure of disorder) can't be destroyed. But if entropy increases from one oscillation to the next, the universe becomes larger with each cycle. "The universe would grow like a runaway snowball," Frampton said. Each oscillation will also become successively longer. "Extrapolating backwards in time, this implies that the oscillations before our present one were shorter and shorter. This leads inevitably to a Big Bang," he said.

Frampton and Baum circumvent the Big Bang by postulating that, at the turnaround, any remaining entropy is in patches too remote for interaction. Having each "causal patch" become a separate universe allows each universe to contract essentially empty of matter and entropy. "The presence of any matter creates insuperable difficulties with contraction," Frampton said. "The idea of coming back empty is the most important ingredient of this new cyclic model."

This concept jolted Frampton when it popped into his head last October.

"I suddenly saw there was a new way of solving this seemingly impossible problem," he said. "I was sitting with my feet on my desk, half-asleep and puzzled, and I almost fell out of my chair when I realized there was a much, much simpler possibility."

Also key to Frampton and Baum's model is an assumption about dark energy's equation of state -- the mathematical description of its pressure and density. Frampton and Baum assume dark energy's equation of state is always less than -1. This distinguishes their work from a similar cyclic model proposed in 2002 by physicists Paul Steinhardt and Neil Turok, who assumed the equation of state is never less than -1.

A negative equation of state gives Frampton and Baum a way to stop the universe from blowing itself apart irreversibly, an end physicists call the "Big Rip." The pair found that in their model, the density of dark energy becomes equal to the density of the universe and expansion stops just before the Big Rip.

New satellites currently under construction, such as the European Space Agency's Planck satellite, could gather enough information to determine dark energy's equation of state, Frampton said.

Physicists at UNC have created a model of the universe that requires no Big Bang. Rather, it breathes new life into a once discarded theory of an oscillating universe. Granted, it is only a competer simulation, but it's still fascinating...

I have a hard time feeling comfortable assuming the red shift is entirely due to velocity.

Since most "stable" elements have an infinitesimal decay rate, then why not assume photons also have a similar inherent instability. The time scale across the observable universe is so vast that it is hard for a mind to grasp that there might be an unknown mechanism that bleeds away a tiny little bit of energy from a photon and thereby reduces its frequency at a constant rate, mimicking the typical delta velocity/distance relationship. This wouldn't mean the BB is wrong, but it could mean that there is a generally stable universe punctuated by "little" bangs.

THE WORDS BIG BANG THEORY SAY ITS ALL" THEORY " NO ONE KNOWS FOR SURE

Since most "stable" elements have an infinitesimal decay rate, then why not assume photons also have a similar inherent instability. The time scale across the observable universe is so vast that it is hard for a mind to grasp that there might be an unknown mechanism that bleeds away a tiny little bit of energy from a photon and thereby reduces its frequency at a constant rate, mimicking the typical delta velocity/distance relationship. This wouldn't mean the BB is wrong, but it could mean that there is a generally stable universe punctuated by "little" bangs.



This very suggestion was made during the last century to explain the redshift. It's known as Tired Light. Unfortunately, it runs up against some observational problems. Perhaps the biggest is the cosmic microwave background radiation (CMBR). The distribution of different frequencies of radiation match what's known as the blackbody curve. The problem arises in that the CMBR should also undergo redshift like galaxies do. But when it does it loses the characteristic blackbody distribution. This means that you have to assume that the CMBR actually has a different distribution and that we just happen to be located at a special place in the universe where it just happens to look exactly like blackbody radiation. Explaining the CMBR is perhaps the greatest challange facing alternate cosmological theories.

I am not qualified to give anything but a layman's opinion on this, but my gut feeling is that the science community is going down the wrong road when it comes to inflation theory. Everything makes sense up to that point, and it just seems to me that a simpler, more reasonable explanation is photon decay resulting in the apparent red shift.

There's also the problem of how matter is arranged in the universe. If we remove the expansion of timespace, we loose our explanation for clustering in galaxies.