Time is our perception of entropy working in one direction, increasing. Time moving backwards would imply entropy is decreasing, and this does not happen naturally
sources:
Stephen Hawking, brief history of time chapter 7 i think
It is possible to imagine a few scenarios in which time is non-linear. For example, an object could be removed from the present and reappear in the future, or occupy another universe for a duration while simultaneously leaving and returning to a single moment in this universe.
Backwards time travel is not possible as you would be creating matter, antimatter, particles, etc. or energy at one point in time while destroying it in the other.
Since all is pre determined (see cause and effect) A => B is already set, this makes the experience of time only a perception of A => X. One can view the experience of time as characters in a movie, they don't know the end but the movie already has one. Linear time is only a perception of A => X.
Time is only a system of measuring and comparing, devised by mankind. Change occurs and we use time as a means of understanding that change but it is change we are observing.
vintagesapiens
