Time traveling backwards is not possible. Time Traveling forward happens the faster you move. Satellites have to compensate for the fact that time is different the faster you go.
I think it's "time traveling forwards happens slower the faster you move."
The easy explanation is that we're traveling in a 4 dimensional space at the speed of light, and any increase in speed in the 3 spatial dimensions must subtract from your speed in the orthogonal time dimension.
If I jump on a ship and travel near light speed (Not possible yet) and then land on the same spot I would not have spent the same time as those on the earth.
Now at a tiny level anyone ever on an airplane also will have spent less time than those who never have flown.
I have always wondered, when satellites have to have their clocks compensated, is it that they are experiencing time differently, but are still in present time?
To rephrase it, how does one know they are not in "now" but the past? apart from maybe measuring ages of their counterparts etc.
Travel back in time and travel faster than light are logically equivalent, and seem to be utterly impossible in our universe. “c” does seem to be the iron law, the speed of causality, but of course who knows? I don’t see a universe without causality having people in it though!