You’ve had this late night conversation with a friend. At least, you’ve seen Back To The Future. And you’ve wondered, “What would happen if I went back in time and killed my grandfather?” Scientific American reports that according to recent studies, you would probably be ok.
Basically, scientists figure that you could theoretically travel to the future, because you’re always moving forward in time, and if you had somehow accelerated and traveled fast enough, you would blow past all those people experiencing boring regular time and end up in the future. Scientists also figure that it’s theoretically possible to bend time back in on itself through a powerful gravitational field like that of a black hole.
Then, there are the paradoxes of time travel. Paradoxes like that whole if-you-killed-your-grandfather-you-would-have-never-existed thing. And when scientists crunch the numbers for theoretical models of these paradoxes, the numbers come out like 1+1=refrigerator. Shit doesn’t compute.
For a long time, some scientists have believed that if time travel was possible, you simply wouldn’t be able to kill your grandfather. Some Final Destination stuff would happen and you’d get hit by a truck, or you’d have a heart attack before you did it. But a new study theoretically deduces that you actually could kill your grandfather. New mathematical models (that actually compute) suggest that if you entered a wormhole to go “back in time,” you would, more or less, come out in an alternate past universe on the other side.
“That is, a time traveler who emerges from a Deutschian CTC enters a universe that has nothing to do with the one she exited in the future.”
So you could go kill your grandfather. But it wouldn’t be your grandfather. It would be an alternate universe grandfather, in what amounts to a clone of the past. So you would never be born in that universe, but you would still continue existing.
TL;DR The universe is more Sliders than Back To The Future. Scientific American has the story, and the paper is here.
