Robert Comsol wrote:
Assuming Psi 2000 had an orbit around its star not too dissimilar from our Earth you'd always be arriving at a different (and empty) spot in space as the planet hasn't gotten there, yet...
Unless your time machine is a spaceship, too (apparently the screenplay writer of "The Alternative Factor" understood the problem!), your time travelling would be limited to exact and full solar years.
This argument is very similar to the one I noted above where causality is selectively followed. That a time machine would appear out in space where the Earth was
at the initiation of time displacement ignores all inertia. What if time is like shuttling fast-forward on video? Then the "world line" of the machine would remain tied to the environment. That might make for a rough ride. So time traveling in open space might be safer. Or perhaps a time machine would shoot off at a tangent to the movement of the Earth?
The follow-up point I wanted to make is that the Earth moves around the Sun, the Sun around the galaxy, the galaxy around its cluster, etc. So while the "limited to one Solar year" argument ignores the inertia of the Earth, it obviously mandates the inertia of everything from the Solar level up.
So which is it: No inertia at all, or Time And Relative Dimensions In Space?