Researchers recreated conditions after the Big Bang and found that time only travels one-way.
During 2010, world-famous physicist Stephen Hawking proclaimed time travel possible. Now two electrical engineers, Igor Smolyaninov and Yu-Ju Hung, both from the University of Maryland, beg to disagree with the famous Oxford scientist.
Their experiment described in "Modeling of Time with Metamaterials," recreates the conditions since the creation of the universe and shows time travel to be unattainable.
A simulated universe
The two simulated the universe by using an exotic substance called "metamaterial." By measuring the path of the light inside it they duplicated the expansion of space.
The metamaterial was composed of plastic strips attached in a pattern on a gold wafer and lit by a laser.
They explained the material mimics the universe by duplicating the mathematics found in general relativity. Therefore, by creating an electromagnetic space with the material, they also created a virtual universe following the mathematics of space time.
In terms of physics, the science news website PhysOrg.com states "...the way light moves in the metamaterial is exactly analogous to the path—or “world line”—of a massive particle in (2+1)-dimensional Minkowski spacetime."
Breaking it down for the non-scientific man-on-the-street, Smolyaninov and Hung's study shows how the experiment recreated the Big Bang within the metamaterial by directing the pattern of light into a pattern that corresponds to the actual start of what cosmologists refer to as "cosmological time"—or time that is measured in the expansion of the initially created space time continuum.
The two point out that as the expansion progresses in the material, light also expands, but imperfectly. That's caused by imperfections in the strips adhered to the gold substrate material. The light progresses and expands as the universe itself does, until it reaches a state of high entropy.
And that state mirrors the universe and the equations describing the Big Bang, its rate of expansion and eventual termination, a "thermodynamic arrow of time" as they refer to it, following the math that proves entropy in an isolated system has a tendency to increase.
Time 'flows," but only in one direction
The model they created simulates the actual universe and adheres to the mathematics supporting the physics of the universe. They stress that as all these conditions are met, the cosmological and the thermodynamic arrows of time coincide. And this meeting points only ahead, or forward.
The experiment is important because not many ways have been developed to test the mathematics supporting the Big Bang expansion theory and the theory of space time. In essence, Smolyaninov and Hung have repeated creation in the laboratory and shown that the math supporting the idea that time can only be a one-way street is valid.
CTCs and time travel models
Some of the mathematics of time travel that have gained supporters over the years describe a condition called "closed timelike curves" (CTCs). Those are particles that travel in a circle and end up where they started.
The two engineers believed they could manipulate the light to create CTCs in their Big Bang model. Yet when they attempted to do so some of the light rays weren't able to return to their origin. As they describe in their study, light could not perceive the correct timelike dimensions, while light that could cannot move in circles.
They could only conclude after their efforts that the physics driving the universe will not permit the creation of CTCs and that, unfortunately, closes the door on time travel.
For those time travel enthusiasts and hopeful chrononauts, the engineers do concede that although time travel seems impossible according to their model, other universe models may permit time travel to occur.
But of that possibility only time will tell.