Major problem with time travel

Movies that feature time travel or even the general conception of the idea is like this: You retain your position in space and travel through time to appear at the same place in future or past. Here is my problem, did nobody else foresee this? If you go back in time and conserve your momentum( seems like a must) to appear at the same place, you will most likely end up in empty space or in a star because the earth, solar system, milky way galaxy fucking moves in space. With our current momentum we can't match Earth's motion through space and all travelers will die in vain.
Jumping in your DeLorean and appearing at the same place in future huh? No, you will drift in space with 85 miles per hour to eternity.

>>22
wow, real solid arguments i am ashamed for all of us. i'm not him but wormhole theory is a plausible one and consistent with their explanations of dimensions. From a higher dimension you could create shortcuts in the lower one. To go from 1 to 10 in a 1-d numbered line, you have to cross all numbers in between. But from a 2-d space you could disappear from the line in "y-axis" and reappear at 10 without even meeting the numbers in between. So if you could reach 4-d you could create shortcuts in 3-d. Since they assume 4-d is time wormholes is suggested to be a way to travel through time but let's not bother with semantics. It is true time and space thus velocity are intertwined and that is why it will violate the laws when you travel a million light year distance in several minutes. But only for an observer from a 3-d world.