From the mathematical standpoint, the quantity that enters into such relation as the equation of motion can be either positive or negative, and the fact that time is observed to move only in one direction is frequently characterized as an anomaly, a “puzzle.” But there is nothing puzzling about the direction of time if it is viewed in physical terms. Time, as a physical quantity—the time interval between two events, for instance—cannot be less than zero. The net magnitude of a quantity of time is therefore positive in all cases. The physical arrow points forward.
A related issue that remains unresolved in the present-day mathematical version of physical theory is the question as to why time has the characteristics of a continual flow. Paul Davies describes the situation in this manner:
It is one of the most perplexing puzzles in physics that the elementary conscious experience of time—the flow or motion of the present moment—is absent from the physicist’s description of the objective world.
The truth is that the physicists are not entitled to expect that their theories, which compensate for the errors in their basic premises by more complex mathematics, rather than correcting the errors, will answer the physical questions. For the answers we need to go beyond the mathematical relations and examine the physical aspects of the phenomena under consideration. This is what has been done in the development of the theory of the universe of motion. When time is examined in the light of the new information derived from this theory, we find that its “flow” is due to a motion of our reference system relative to the natural reference system, the system to which the universe actually conforms.