Our Universe May Have Been Recycled from an Earlier Universe

Most cosmologists believe that our universe emerged from a singularity during the Big Bang. But now physicists are exploring the possibility that our universe was created by the death of an earlier universe.

Martin Bojowald and Abhat Ashtekar began researching their theory of loop quantum cosmology (LQC), an approach to cosmology that combine’s Einstein’s theory of gravity with quantum mechanics. They have modeled the birth of our universe, exploring the mathematics of universe as it contracts back toward its point of origin.

Bojowald's major realisation was that unlike general relativity, the physics of LQC did not break down at the big bang. Cosmologists dread the singularity because at this point gravity becomes infinite, along with the temperature and density of the universe. As its equations cannot cope with such infinities, general relativity fails to describe what happens at the big bang. Bojowald's work showed how to avoid the hated singularity, albeit mathematically. "I was very impressed by it," says Ashtekar, "and still am."

The researchers have found that when applying LQC, the universe does not revert back to a singularity as it contracts. Instead of seeing a big bang, the models indicate that the universe experienced a big bounce, with a predecessor universe contracting as it ended and then reemerging as our new, expanding universe. If the theory proves correct, it could mean that our universe does not have a finite beginning and end but is, instead, part of a chain of universes that expand and then contract to give way to a brand new universe.

Did our cosmos exist before the big bang? [New Scientist]