And this is the main point that makes time travel in movies completely unbelievable to me. According to the theory or relativity, there are no absolute coordinates. And even if their were, is earth the center of the universe that stands still? So how could you jump for one time to another and expect to land in the same relative coordinates to the earth. As the author of the articles says, there would need to be end points at both ends of the leap. Like two time machines. Or some naturally occurring end points. The only other option is to move through time and space at the same time(much like we do naturally), and not instantaneously jump through time.

If there are no absolute coordinates then there is an arbitrary choice of coordinate system and you are welcome to choose your jumping off point as fixed.

When I jump I push the entire universe down by about 30cm.

Makes the maths a reall bugger to work out though.

You don't travel through time. Time is not a physical thing that you can move through. Time is not a river, or a place on a map.

What is time on an atomic level? It's the speed at which interaction occur, transfer of energy mainly.

When you move at relativistic speeds those interactions occur "slower" (which is a self referential statement, but nothing I can do about that).

But you do not travel though time - you don't travel at all. The various forces that affect you work slower. It's like slowing down the motor of an assembly line robot. You are not moving through time just that things that you are made of do their thing less often.

Since you are moving slower, the rest of the word seems to move faster.

Which is why time travel is impossible - there is no place to travel to.