Comment: Re:not a fan (Score 1) 373
There is no "absolute position". Anything running on inertia can be said to be said to be moving at any velocity you choose depending on your frame of reference, including motionless. Now, planets don't run solely on inertia -- they orbit because of gravity. But gravity folds spacetime, which is still what you're travelling through. Plenty of good reason to think you'll end up at basically the same position relative to the barycenter of the most significant gravity sources of your point of departure.
Even if I was to suspend belief and buy this argument that you end up at the same position relative to the barycenter of the most significant gravity sources of your departure (I don't), you would still need to travel through space.
Consider the situation where you travel back in time one hour. The earth is rotating - so if you started on the east coast of a continent, and arrived at the same point relative to the barycenter, you would end up somewhere in the ocean. Even if you were to travel back only in increments of 24 hours to avoid this situation - the earth doesn't spin perfectly- it has processional wobble about a tilted axis - you would end up far above or below ground - not too useful. You would still need some sort of space travel.
And things get worse the farther you go back - things like meteor collisions throughout the ages will all jiggle the Earth further and further from the original radius of orbit of the sun. If you travel through time, you will need to also travel through space at some point to get to where you want to go.