Science has long failed to provide anything stable that could suggest what came before the Big Bang. General Relativity curls up in to the fetal position and demands to be left alone whenever anyone brings the idea of “what came before” to it.
Physicists Alejandro Corichi from Universidad Nacional Autónoma de México and Parampreet Singh from the Perimeter Institute for Theoretical Physics in Ontario, are proposing that what came before the Big Bang may have been eerily familiar.
A new theory called Loop Quantum Gravity (LQG) has cropped up in recent years, and while there is a lot of math and science to this theory, one of its assumptions is that instead of a Big Bang spacetime singularity, there was a Big Bounce.
“The significance of this concept is that it answers what happened to the universe before the Big Bang,” Singh told PhysOrg.com. “It has remained a mystery, for models that could resolve the Big Bang singularity, whether it is a quantum foam or a classical space-time on the other side. For instance, if it were a quantum foam, we could not speak about a space-time, a notion of time, etc. Our study shows that the universe on the other side is very classical as ours.”
Previous work on the LQG showed that there had been a universe on the other side, but while it showed valid math, there was no chance to observe in our current universe the state of the pre-bounce universe. This is because, under the previous theory – worked upon by Penn State physicist Martin Bojowald – there was nothing preserved across the bounce. Bojowald described this as a sort of “cosmic amnesia.”
Corichi and Singh have modified the LQG by approximating a key equation called the quantum constraint. Their version is called the sLQG, and it shows that the relative fluctuations of volume and momentum in the pre-bounce universe are conserved across the bounce.
“This means that the twin universe will have the same laws of physics and, in particular, the same notion of time as in ours,” Singh said. “The laws of physics will not change because the evolution is always unitary, which is the nicest way a quantum system can evolve. In our analogy, it will look identical to its twin when seen from afar; one could not distinguish them.”
“In the universe before the bounce, all the general features will be the same,” said Singh. “It will follow the same dynamical equations, the Einstein’s equations when the universe is large. Our model predicts that this happens when the universe becomes of the order 100 times larger than the Planck size. Further, the matter content will be the same, and it will have the same evolution. Since the pre-bounce universe is contracting, it will look as if we were looking at ours backward in time.”
But the researchers are quick to point out that this second universe is not full of duplicates of us. It does not suggest that every particle on the other side is exactly the same, and that there is someone who has lived your life. It is pretty much as if the “evil Spock” from the old Star Trek episodes had been from the previous world, not a parallel dimension.
A non-Star Trek description would be; “If one were able to look at certain microscopic properties with a very strong microscope – a very high-energy experiment probing the Planck scale – one might see differences in some quantities, just as one might see that twins have different fingerprints or one has a mole and the other does not, or a different DNA,” Singh said.
In the end, Corichi and Singh’s model may even be able to show us what our own future universe will look like. Depending on how fast our own universe is accelerating, there’s a possibility that – through generalizing their model – a re-collapse of our own universe is possible.
Posted by Josh Hill.
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