… Read the rest
Mention time travel at a nerd party, and other guests will immediately respond with a grim conundrum: What happens if a time traveler goes back in time and kills one of his ancestors? This is the “Grandfather Paradox.” In a simulated environment, a team of mathematicians tested the paradox, and made a remarkable discovery: In time travel simulations, at least, history repeats itself.
The Grandfather Paradox makes a mess of time travel. A murderer kills his ancestor, preventing his own birth, thereby preventing the murder, thereby being born, thereby committing the murder, and so on. To observe it, a team of researchers, led by Martin Ringbauer, created a simulation. Instead of firing up a DeLorean to 88 miles an hour, they sent photons through a “closed timelike curve,” or CTC. The photons are paired up so that one follows the other. It works like this:In their new simulation Ralph, Ringbauer and their colleagues studied Deutsch’s model using interactions between pairs of polarized photons within a quantum system that they argue is mathematically equivalent to a single photon traversing a CTC.