jtotheizzoe:On June 28, 2009, Stephen Hawking hosted a party for future time travelers He didn’t te
jtotheizzoe:On June 28, 2009, Stephen Hawking hosted a party for future time travelers He didn’t tell anyone about his plans until after it was over.Sadly, no one showed up:Sigh.Physics suggests that backwards time travel just isn’t possible, although one theory says we could sufficiently warp time and space to moonwalk into yesterday if we could harness half of the universe’s matter and energy. So, yeah, not holding my breath there (plus you always have to watch out for those pesky Libyans).Einstein’s relativity does allow for forward time travel, though. That’s thanks to time dilation. In certain circumstances, observers in different frames of reference will experience time differently for one another. Travel very near the speed of light and you’d return home to find everyone you know dead of old age, which would suck because you’d have no one to tell your stories to.Time dilation is more than a thought experiment. Thanks to gravitational differences, astronauts onboard the ISS age 9 milliseconds less than we do for every year they are up there!Russian cosmonaut Sergei Avdayev holds the time travel record, being about 20 milliseconds behind all of us after spending 747 days aboard Mir. GPS satellites experience this kind of time dilation, and have to be constantly corrected to stay in sync with Earth.Of course, if you want to split hairs, we’re all time traveling. Forward, at one second per second … but it’s not as exciting if everyone else is doing it, eh?Limited-edition print above by Peter Dean, available here. -- source link