Why does time appear to have one direction?

Answer 1

Time is observed to have one direction due to cause and effect. Time is related to the motion of matter, both internal and external. All matter forms, evolves, and eventually decomposes into nothing or changes into another form. This is due to the internal motion of the atoms and molecules that are the building blocks of matter. The external motion is the movement of matter through space. Humans observe all of this motion in terms of past, present, and future. The past refers to the finality of all motion preceding. The present refers to all motion already in progress. And the future refers to the inevitability of the end of all present motion and of all motion succeeding.

I agree with John. Actually time is nothing but "change". Change s some are reversible and mostly are irreversible. Growth is irreversible. Just based on this we think that time is to travel in one direction and no chance to take back. But if we go beyond these material boundaries then there lies the chance to move back and this is what we call time travel.