You can travel no further back in time than 1955

18 August 2009

The Time Traveler’s Wife is the latest in a long line of time travel themed movies, and according to physicist Dave Goldberg, makes for a more realistic representation of time travel than most of the (fiction) served to date.

But this is interesting, time travel is (theoretically) only possible to points in time where a time machine already exists, according to Goldberg.

In other words, for Marty McFly to travel from 1985 to back to 1955, as he did in Back to the Future, a DeLorean like time machine would already need to have been in existence in 1955…

According to Einstein’s picture of the universe, space and time are curved and very closely related to each other. This means that traveling through time would be much like traveling through a tunnel in space — in which case you’d need both an entrance and an exit. As a time traveler, you can’t visit an era unless there’s already a time machine when you get there — an off-ramp. This helps explain why we’re not visited by time-traveling tourists from our own future. Futuristic humans don’t drop in for dinner because we haven’t yet invented time travel.

Of course the concept of time travel — in the form of the Flux Capacitor — did exist in 1955, it simply hadn’t taken physical form… does that count?

Originally published Tuesday 18 August 2009, with subsequent revisions, updates to lapsed URLs, etc.