A new challenge to classical cosmology comes from a novel field named loop quantum cosmology (LQC), which started from applying rules of loop quantum gravity on the context of general relativity. The new vision states that the universe we live in did not emerge from an infinitely small particle with a similarly infinite mass (the dreadful singularity all scientists have been trying to avoid). Instead, the authors claim that another (possibly similar)
universe existed before.
The laws of physics to which singularity abides are still elusive, but theoretical aspects suggest that it is highly likely that Planck-scale densities are impossible. So, Martin Bojowald, an assistant professor of physics at Pennsylvania State University, and Abhay Ashtekar, Eberly professor of physics and director of the Institute for Gravitational Physics and Geometry at the same institution, have devised a model where the universe is the result of another kind of Big Bang, called a Big Bounce.
In their vision, another universe existed before our own, but at some point, due to gravity, it started to contract and collapse upon itself, much like a dying star, but on a far greater scale. It is estimated that it had not reached the Planck density of 5.1 × 1096 kilograms per cubic meter, the rough equivalent of the mass of some trillion Suns squashed to the size of one atom (but it wasn't far, either), when an immense repulsive force occurred in the fabric of space-time, overcoming gravity. This caused the matter to expand all over again, in what is, perhaps, a cyclical process.
Although the cycles of inflation and deflation are not a new concept, the complicated theory (which involves superinflation and a particle called inflaton) is the first that fits in the large picture. The developers of the novel concept are striving to improve their theory by using the latest technology to search for patterns in the gravitational waves in the cosmic microwave background (CMB). Whether a similar fate awaits our own universe is yet unknown, but some speculate that the effects of the dark energy that pushes the universe apart might reverse at some point, causing it to collapse and go through the same process all over again.
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