Time Travel--evolved thoughts

Actually the problem with time travel (I know, what does this have to do with Language, Poetry OR Gardens?) never seems to be discussed at all--though I'm sure it HAS to have been broached somewhere. It's this: Matter cannot be two places at the same time. A body is nothing but a sack of molecules. And every molecule in your body already exists at any time you would want to come from or go to. You see the problem? A body cannot come back in time because IT'S ALREADY THERE--not in the person who exists (perhaps) under the same name, i.e. not in a younger self. That's the least of the issues, since his body won't necessarily have very many of the same molecules (a little out of my league with that claim), but because the molecules that make up the body in 2056 exist in loaves of bread and the bark of trees and the guts of whales in 1972. If I go back from the one time to the other, where am I going to get the molecules? These are not copies of those molecules. They are the same molecules. I don't see a solution for this problem.