Let’s say some guy has found a way to travel backwards in time. No machine, just to keep it simple, he just has the ability to step through time just as easily as anyone can move through any of the three spatial dimensions.
Now say he goes back in time 1000 years without moving in any other direction. It seems he would be going to will have been* standing in that spot for the entirety of those 1000 years. Presumably he would be timeless and unaffected by anything going on around him but people would still be able to see him and react to him. What might the implications of this be? Would he have to move into at least a fifth dimension to get out of the way of the Universe? Would this make time travel impossible? (If it isn’t already)
[sub]*[Obscure Hitchhiker’s reference] I could do with a copy of Dr Dan Streetmentioner’s Time Traveller’s Handbook of 1001 Tense Formations.[/Obscure Hitchhiker’s reference]
Your time traveller would be somewhere out in intergalactic space, gasping for breath.
In that thousand years, the Earth, solar system and entire arm of the Milky Way has moved. A long way.
Your time traveller would also want a space machine, as well as a time machine, to ensure that he can, first, locate the earth and, second, get back to the earth.
Yes, this problem has occurred to me, as well, most notably in the great and scholarly tome, The Time Machine. I’ve always thought, “Wouldn’t the world, nay, the galaxy, nay, the whole universe, move out from underneath the traveller?”
I eventually came up with the conclusion that, for the sake of remaining internally consistent with the story, that the traveller automatically “drifts” along with the universe… a person is still affected by gravity/inertia/momentum/etc. while travelling through time.
Of course, you could write you own sci-fi story in which this weren’t the case, and have your traveller travel through time only to find that some alien world had drifted underneath him.
I think this has been done… ISTR a pre-Golden-Age story which used this idea - might have been by Clark Ashton Smith, but I couldn’t swear to it.
The idea in the OP was addressed in Cordwainer Smith’s short story “Himself in Anachron”, which involved a time traveller having something of an accident and watching a religious cult evolve around his time-frozen body (actually, devolve, since he was going backwards at the time).
Whether this says anything about the impossibility of time travel, I’m not sure - I’d always regarded it as pretty much impossible anyway, in terms of a) our current understanding of physics and b) boring old notions like causality.
[Moderator Hat: ON]
Since we’re talking science fiction here, I think it belongs over in IMHO. So that’s where I’m moving it.
David B, SDMB Great Debates Moderator
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