Question

what do you mean by time reversal symmetry of a particle?

Answer 1

If you run events in reverse, the same laws of physics hold.

Answer 2

was that an electron moving forward in time , or a positron moving backwards in time/

Answer 3

No, that's not what is meant. The time reversal of an electron moving to the right with velocity \(\vec v\) is an electron moving to the left with velocity \(-\vec v\). It's as if the video were being played backwards.

Answer 4

moving backward in time the electron will be attracted to negative