system
Given the following post, respond as if you're commenting on Reddit:
human
[Time Travel] how can you move through time and end up in the same place?

   In the time travel documentaries I have seen, and read recently there is a constant theme that has me confused. How do the Time Machines move through time, but end up in the exact same place (geographically) that they left. Wouldn't the Earth have moved a GREAT distance over the time that was traveled leaving the time travelers in empty space when they arrive at their destination?

   Take The documentary Back to the Future. How does Mr. McFly travel from the 80's to the 50's but remain on the same stretch of road? I only witnessed him inputting the date, not the spacial location he was supposed to arrive at.
gpt
Time machines deal in *space-time coordinates* generally. This means that when they travel through time, they also travel through space - presumably, if no *space* portion of the coordinates are entered, the time machine will automatically calculate how to travel to approximately the same position in another time. This would involve calculating for all movement - a difficult proposition certainly, but by no means impossible.