This blog does and does not exist • Five Things to Know About Time Travel Physics

Five Things to Know About Time Travel Physics

1. Back the the Future and the Grandmother Paradox: One challenge of time travel to the past is that you could inadvertinently do something that would make your own existence impossible—like when Marty McFly threatens to keep his own parents from hooking up after he lands a DeLorean in 1955.

2. What about Bill and Ted? In the 1989 movie, Bill and Ted’s Excellent Adventure, Keanu Reeves and Alex Winter get high marks in history class after they use a time machine, provided by George Carlin, to roundup an A-list of historical fugures to bring to school. No harm is done, so no Grandmother Paradox. Physicists call this the Principle of self consistency, first proposed by Cal Tech physicist Kip Thorne and Igor Novikov, of the University of Copenhagen. The idea is basically that things will happen because that’s the way they happened…

3. Wormholes…all these wormholes: Gliding through time and space in wormholes seems to be the rage in time travel movies these days—it’s practically a given that if you’re doing one or the other, these strange phenomena associated with black holes will serve as the conduit. Consider the movie Contact, bsed on Carl Sagan’s book. Wormholes do indeed offer physicists the most widely accepted possible means of time travel—Thorne has even written extensively on how it could happen (we just need to find “exotic matter”—stuff that weighs less than nothing….).

4. Take us to Warp speed, Mr. Sulu: Kids as young as seven had no problem understanding Einstein’s theory of relativity when Star Trek was on TV. Weekly episodes not only discussed travel at speeds above the speed of light, but also frequently explained how that could allow time travel (Mr. Spock never did explain why sometimes it did and sometimes it didn’t though, did he?). Mexican physicist Miguel Alcubierre documented how the universe could be warped (remember the burrito analogy in Peggy Sue Got Married?) in 1994, and in 1996, physicist Allan Everette figured out how to travel to the past using time-warped space.

5. What about Groundhog Day? In Groundhog Day, Bill Murray relives Feb. 2 over and over… until he gets it right. Forgetting the karma concepts here, there is a way for this to occur in physics, according to Gott, if we envision the universe like a loaf of bread standing on end, which can be sliced in a number of ways—including horizontally. This theory has some trickier physics explaining it, but Gott maintains such possibilities are real.