Sounds like the musing I've done on time travel.  I always hear people say things along the lines of, "You can't time travel to the past because the past isn't a place."  Yes, it is.  If in fact time and space exist on a continuum, then any point in time is necessarily linked to a specific space.  The problem is that you'd not only have to figure out how to travel in time, but be ludicrously dead-on specific about travelling bazillions of miles, too since in all likelihood, THIS space, the one I occupy right now, was completely empty at that point in time.