How did the universe come into existence, a Big Bang or a Big Bounce? In other words, is the reality we currently inhabit brand-new, or is the universe cyclical — inflating and deflating like a balloon over and over again?
In a new study published Wednesday in the Physical Review Letters, a team of international scientists has attempted to answer this eternally vexing question. The paper, titled “Perfect Quantum Cosmological Bounce,” argues that the cosmos we exist in may have been formed from an older collapsing universe.
Although the Big Bounce idea has been around, in one form or the other, since 1922, scientists have faced a key obstacle in explaining how the universe transitions from a contracting to an expanding phase and avoids becoming an “infinite point” in the process. The problem is something that also plagues cosmological models that describe the Big Bang — how does the universe, and everything in it, emerge from a singularity, which, by definition, is a single point that occupies no space at all.
“This is a problem,” co-author Neil Turok, director of the Perimeter Institute for Theoretical Physics in Canada, said in a statement. “The standard cosmology begins with an impossibility.”
The present-day universe obeys two seemingly incompatible laws — with quantum mechanics governing the behavior of subatomic particles and relativity describing how clumps of atoms — humans, stars and galaxies — behave. Formulating an all-encompassing Theory of Everything, one that resolves the apparent contradictions between quantum mechanics and relativity has, for the longest time, been the holy grail of particle physics.
The study, which, among other things, attempts to resolve this seemingly insurmountable problem, states that the universe, in its earliest stages, would have exhibited a phenomenon known as conformal symmetry — wherein physical laws governing the entire universe would also have worked at the scale of subatomic particles.
If this is true, the researchers argue, the exact moment of the “bounce” from contraction and expansion can be explained using well-established mathematical model that describes quantum tunneling — a phenomenon in which a particle tunnels through a barrier it cannot cross. According to the researchers, the universe achieved (and will achieve) this transition by approaching the singularity point and then skipping over it by temporarily accessing another dimension.
In this model, the transition is smooth, and the universe avoids passing through that single point where physics seems to break down.
“Quantum mechanics saves us when things break down,” Steffen Gielen, a fellow at Imperial College London, said in the statement. “It saves electrons from falling in and destroying atoms, so maybe it could also save the early universe from such violent beginnings and endings as the big bang and big crunch.”