Time travel is a common theme in science fiction media and is captivating. The late philosopher David Lewis, in his essay The Paradoxes of Time Travel, defines it as “[involving] a discrepancy between time and spacetime. Every traveler departs and then arrives at their destination; the elapsed time from departure to arrival… is the journey duration.”
Time travel is understood by most as going back to a bygone era or jumping forward to a point in the future. But how much of the idea is based on reality? Can you travel through time?
Is time travel possible?
According to NASA, time travel is possible, just not in the way one might expect. Albert Einstein’s Theory of Relativity states that time and motion are relative to each other and that nothing can travel faster than the speed of light, which is 186,000 miles per second. Time travel occurs through something called “time dilation”.
According to Live Science, time dilation is how one’s perception of time differs from another depending on its movement or location. So time is relative.
dr Ana Alonso-Serrano, a postdoc at the Max Planck Institute for Gravitational Physics in Germany, explained the possibility of time travel and how researchers test theories.
Space and time are not absolute values, said Alonso-Serrano. And what makes it even more complex is that you are able to carve spacetime.
“The moment you carve spacetime, you can play with that curvature to make time come in circles and build a time machine,” Alonso-Serrano told USA TODAY.
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She explained how time travel is theoretically possible. The math behind the curvature of spacetime is solid, but trying to replicate the rigorous physical conditions required to prove these theories can be challenging.
“The tricky part here is whether you can find a physical, realistic way to do it,” she said.
Alonso-Serrano said that wormholes and warp drives are tools used to create this curvature. The matter needed to reach curved spacetime via a wormhole is exotic matter, which has not been successfully accomplished. Researchers don’t even know if this type of matter exists, she said.
“We’re working on it because it’s theoretically possible and because it’s a very nice way to test our theory and look for possible paradoxes,” added Alonso-Serrano.
Besides the above methods, Alonso-Serrano is unsure if there are any other methods that allow time travel.
“I can’t say nothing is possible, but I can’t ignore the possibility,” she said.
She also mentioned the anecdote of Stephen Hawking’s champagne party for time travelers, where Hawking had a GPS-specific location for the party. He didn’t send out invitations until after the party had already taken place, so only people who could travel in time could attend. No one showed up, and Hawking called the event “experimental proof” that time travel was not possible.
This article originally appeared on USA TODAY: Will Time Travel Ever Be Possible? The science behind the possibility.