Time as we know it is something extremely complex that according to many researchers around to globe, isn’t fully understood. We, humans, experience time in one direction meaning that we all get older, we remember our past but we cannot look at the future. However, nothing in the known laws of physics tells us that time MUST move forward.
Among other theories, some suggest the Big Bang was not the beginning of the universe and that we may be living in the past of a parallel universe.
In order to try and solve the biggest mystery of all, two separate groups of prominent scientists are creating models that are able to examine the initial conditions in the universe that might have created what we call ‘arrow of time’. Interestingly, both groups seem to show time moving in two different directions, a contradictory finding according to many researchers around the globe.
Scientists believe that when the Big Bang created our universe, it also created a second ‘mirror universe’ where time actually moves in the opposite direction. Looking at it from our perspective, time in the parallel universe moves backward. However, ‘anyone’ inside the parallel universe would perceive our universe’s time as if it were moving backward:
The first model which was published over a year ago in Physical Review Letters tells us that one of the most basic implications proposed in Newton’s theory of gravity creates the necessary conditions for time as we know it to move in a certain direction.
According to Julian Barbour from the University of Oxford, Tim Koslowski from the University of New Brunswick and Flavio Mercati from the Perimeter Institute for Theoretical Physics, for any confined system of particles—a self-contained universe like the one we live for example—gravity creates a point when the distance between particles is reduced to a minimum. But, when the particles expand outwards, it occurs into different temporal directions, researchers argue.
According to quartz.com, Barbour and his colleagues created a simplified 1,000 particle point model of the universe showing this dual expansion, with gravity creating structure in both directions.
According to the Second Law of thermodynamics, systems like that converge and expand by necessity explains, Flavio Mercati.
The Janus point
According to researchers, the moment before the ‘expansion’ is referred to as the “Janus Point”.
In an interview with Quartz.com, Barbour explains “Time is not something that pre-exists.”
“The direction and flow of time we have to deduce from what’s happening in the universe. When we look at it that way, it’s natural to say that time begins at that central point and flows away in opposite directions.”
To simplify the explanations, Barbour compares the so-called Janus Point to the moment a river splits in two and flows in opposite directions.
“It’s the simplest thing,” he says. “You start at that central Janus point where the motion is chaotic –that’s like the Greek notion of primordial chaos—but then in both directions, you get this structure forming. If the theory is right, then there’s another universe on the other side of the big bang in which the direction of experience of time is opposite to ours.”
While the above-mentioned theory isn’t accepted by all researchers, it did create excitement in the scientific community, what led towards more scientists exploring the theory.
Now, a new study, reported by popular website New Scientist suggests that two other researchers, —Sean Carroll from California Institute of Technology in Pasadena and Alan Guth from Massachusetts Institute of Technology— have come up with a similar model that demonstrates time moving in both directions, in ‘parallel universes.
Even though their study remains unpublished, the two researchers agree that their theory is, even more, simplified than that proposed by Barbour and his team since their study does not rely on gravity or particles confined in another system. According to reports, the study proposed by Carroll and Guth is based on the concept of entropy alone and does not include any other preconditions, meaning that it applies to particles in ‘infinite space’ rather than self-contained systems as in previous studies.
“We call it the two-headed arrow of time,” Guth tells the New Scientist. “Because the laws of physics are invariant, we see exactly the same thing in the other direction.”
The theory, however, is far from being accepted in the scientific community as reports suggest. According to New Scientist, there are initial stages in the model where the direction of entropy growth—and so the arrow of time—is not clearly defined, and so difficult to account for.
Barbour added that the work is being based on everything we know about classical physics.
Once questions of quantum physics are introduced, “all bets are still off.”
He adds: “Instead of having two streams emanating from a river, it could be more like a fountain where you have lots of pairs of springs. Or just a whole host of springs flowing out of a fountain in different directions.”
Featured Image Credit: NASA