Does Time Really Exist?
What is it that clocks are measuring? They seem to measure some unseen medium that continues on at a constant and unyielding pace. Time is often thought of as a river that flows in one direction and slows for no one, it sweeps us along with it. Is there any evidence that it is really there or is it much like the ether that was once thought to permeate the universe. Certainly we experience time's passing. People are born, live, and die and feel as though they are constantly being pushed or dragged by this unseen phenomenon. Therefore, time must exist, right? Perhaps. But consider that time is something that we perceive through our senses, which are not perfect. Is it possible that how we think about time is related to how our brains processes information?
In Book XI of Confessions of St. Augustine the illustrious St. Augustine discusses the nature of time and how God and free will fit in. I do not want to discuss theological implications of time here, though there is much that could be said on the matter. However, some of his thoughts on time are very insightful and I will attempt to explain them. First, let us consider how people often speak of time periods as having duration. For instance I might say I believed a road trip to take a very long time. But how is it that I can justify saying that a past or future time is long. I might say that a past time was long or a future time will be long. However, if the past is no more and the future is yet to occur then how could its duration be measured? Indeed, if the past no longer exists and the future is yet to exist then all that remains is the present. But the present has no duration. One can divide any period of time into a past and future, from millenia to picoseconds. The present is nothing more than a fleeting moment through which the future passes to become the past. So we are left with quite a conundrum, the past and future do not exist and the present has no duration, how can time be measured.
St. Augustine proposed that time is measured in the mind. It is not an event itself that is measured but the impression that it leaves on the mind. The mind expects the future, which becomes the present, which the mind attends, and then becomes the past, which the mind remembers. The future and past do not exist, but in the mind there is expectation of the future and remembrance of the past. The present has no duration and still the mind's attention persists. So it is not the future which is long but a long expectation of the future. Likewise, it is not the past that was long but a long remembrance of the past. St. Augustine ended his discussion of time with the conclusion that it is something measured in the mind, a human conception. This is all the further one can go based on logic alone. So let us now turn to the realm of physics and discover what might be learned about the nature of time there.