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barberoux
01-15-2008, 08:33 AM
It seems to me that the earth is spinning plus it is moving in orbit about our sun which is in a spiral galaxy that is spinning plus it is in an expanding universe so it is moving away from the center. If everything is moving a person time traveling would reappear in the same place he was when he left but the earth would have moved on so he would be in outer space. Time travel speculations never seem to address spatial travel as well. The traveler may go back in time to the age of dinosaurs but the earth was in a different part of the universe. He would have to be connected somehow to the physical location as well as the time location. Why is this never addressed in discussions about time travel? http://www.straightdope.com/classics/a4_181.html

Mangetout
01-15-2008, 09:21 AM
It seems to me that the earth is spinning plus it is moving in orbit about our sun which is in a spiral galaxy that is spinning plus it is in an expanding universe so it is moving away from the center.
What centre?

If everything is moving a person time traveling would reappear in the same place he was when he left but the earth would have moved on so he would be in outer space.The same place relative to what? There's no such thing as absolute position.

Time travel speculations never seem to address spatial travel as well. The traveler may go back in time to the age of dinosaurs but the earth was in a different part of the universe. He would have to be connected somehow to the physical location as well as the time location. Why is this never addressed in discussions about time travel? http://www.straightdope.com/classics/a4_181.html
I've seen it mentioned quite a bit, actually - a couple of stories (I don't remember which) threw in some thing about locking on to the nearest large gravity well. But in general discussions, it comes up a lot - I'd say there's about a 50% chance of it being mentioned in any thread on the subject of time travel on this board.

Exapno Mapcase
01-15-2008, 11:15 AM
If you look at the books I cite in the other time travel thread (http://boards.straightdope.com/sdmb/showthread.php?t=451060) you'll see that movement in space as well a time is a topic that is frequently discussed.

There's not always a need to do so, however, since the theoretical aspects of time travel can be looked at without the additional complication of where one lands. That would be crucial in a real life situation, but so far there aren't any of those. Keeping it simple for discussion works well enough.