Could time travel work?
Yes, Superman flew around the Earth a bunch of times and caused time to start going in reverse (and saving Lois Lane in the process), but really, wouldn’t we all rather punch a date and time into the ol’ Delorean, buckle up and hang on ’til it hits 88 mph?
The time machine is a great concept, so tantalizing in its simplicity — a box, some buttons and wires and voila! You’re getting chased around by T-Rexes.
But the whole idea is too crazy, right? In fact, no, says Ben Tippett, mathematics and physics professor at UBC Okanagan. Tippett and his colleague David Tsang of the Center for Theory and Computation at the University of Maryland in the US have authored a paper showing that, at least in terms of the math involved, time travel could happen.
“People think of time travel as something fictional,” said Tippett, to the Vernon Morning Star. “And we tend to think it’s not possible because we don’t actually do it. But, mathematically, it is possible.”
Ever since Einstein first offered up his theory of general relativity a century ago, physicists, if not us regular folks, have taken to the idea that time is not a universal constant. Rather than travelling forward at the same rate for everyone and everything, time’s progression depends on how fast you’re moving through space and on how close you are to extremely massive objects like planets. In fact, the closer you get to the speed of light, for example, the slower time moves relative to other bodies and Earth’s own gravity makes time move more slowly for things on its surface as compared to things higher in the atmosphere.
Tippett’s own version of a time machine — a “bubble of geometry,” he calls it — takes advantage of Einstein’s theory of curved space-time to “bend time into a circle.” “That circle takes us back in time,” says Tippett.
Published in the journal Classical and Quantum Gravity, Tippett’s new research concedes that mathematics aside, the nuts and bolts of his time machine are not yet available.
“While is it mathematically feasible, it is not yet possible to build a space-time machine because we need materials—which we call exotic matter—to bend space-time in these impossible ways, but they have yet to be discovered,” says Tippett.
Here, though, is where math and logic seem to part, as other big brains have steadfastly claimed that while time travelling forwards is a possibility, going backwards is truly not. The problem is one of causality, they say, neatly summed up in the so-called grandfather paradox whereby it’s said to be impossible for you to travel back in time and kill your own grandfather (because, obvi, then you wouldn’t exist to do the deed in the first place!)
Physicist Stephen Hawking has famously stated that backwards time travel would violate the rule of a cause coming before its effect. “I believe things cannot make themselves impossible,” said Hawking.
Hawking has said that our best hope at building a time machine is to equip a spaceship with enough fuel that it can gradually make its way up to close to the speed of light. After a full four years of increasing its speed, the ship would begin to travel in time slower than we do here on Earth.