Question

what is the direction of time?
can we travel back in time?

Answer 1

the direction of time is defined over the growth of entropy in statistical physics, so if you somehow manage that the entropy of the universe decreases instead of growing, you could do time travel. but the decreasing of entropy is against the laws of thermodynamics, so time travel is not possible in theory of statistical physics. also in the relativity theory it is not possible, because nothing can travel faster than light.

time is not responsible for causality but causality is responsible for time.