hm... that's arguable. Neglecting the fact that it wasn't Einstein, but Everett who came up with the very interesting many-worlds interpretation, it is ruled out to return to the dimension you originally came from, thus rendering your idea of timetravelling food supplies invalid. But I guess we're drifting off here EDIT: I am pretty cool with this theory btw as I owe my existance to WW2 and I guess many people would timetravel to stop this wanton austrian before he did his first "political" steps...
Stephen Hawking had a time travel theory that said if you could some how build a space ship powerful enough to orbit a black hole in the event horizon you would move slower through time. The example he gave was that time would travel something like 50% slower (i forgot the exact number) while in the event horizon. And if you orbited for 5 years, 10 year would have passed on earth. So you would essentially travel forward through time. I have no idea if what he said makes sense but he seems to know what he's talking about.
