Be Careful When Making Assumptions About Time Travel

I have faith that humankind will one day successfully build a time machine. I fear, however, that whoever takes the maiden voyage in this wonder of four-dimensional transportation will find themselves floating in the coldness and blackness of outer space.

As a culture, we have embraced the assumption that if one starts in, say, a field in Iowa and travels back in time 30 years, one will end up in that same field in 1976. Sure, the first time machine would likely be designed such that travelers would journey through time, but remain stationary in the other three dimensions. Thus, spacially, one should not change position.

Here's the problem: Our notion of location is based on one's position relative to the earth's poles. But the earth is revolving on its axis and moving through space around the sun. Moreover, the sun is rotating around the center of the Milky Way galaxy, and the Milky Way is constantly changing its position relative to other galaxies. In other words, what is stationary on earth is nonetheless moving through spacetime. To use the example above, in 1976 that field in Iowa was millions of miles away from where it is today.

Thus to successfully travel through time, one must also navigate a long journey through space.