DIsplacement and Velocity

Question

Velocity can be either positive or negative, depending on the direction of the displacement. The time interval Δt is always positive why

Answer 1

A negative time interval would mean the ending time is earlier than the starting time.  So far, in scientific knowledge, there has not been a way to determine how to make travelling backward in time possible.  Unlike dimensions in space (left-right, back-front, up-down) we are, at present, only able to travel one direction in time.