What is time

Jack Dikian

Sep 2012

Again, as so often these days, casual remarks made in late night conversations sets me thinking about those ideas we hold with seemingly little need for scrutiny. These are ideas that involve everyday concepts, that, on the surface, are supposedly well understood, defined, and seem as natural as day and night. I’m talking about time.

How hard can it be to explain the passage of time. After all, we can measure time precisely and we all have an innate ability to gauge the flow of time.

The question, perhaps overly simplified: is time a "real thing" that is "all around us", or is it nothing more than a way of speaking about and measuring events.

Psychologically, time can seem to take forever or be over before we know it. The past only exists as memory. The future is something we can’t remember. So, there is really only the present. In the novel “The Merry-Go-Round in the Sea”, by Randolph Stow, a novel I couldn't put down when I was 12, Rob's life is "jolted" by the impending war comes to the realisation “I am six years and two weeks old. I will never be that old again”.

Time is one of the seven fundamental physical quantities in the International System of Units. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second.

There are two distinct views on the meaning of time. One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence. This is the realist view, to which Isaac Newton subscribed, in which time itself is something that can be measured.

A contrasting view is that time is part of the fundamental intellectual structure (together with space and number) within which we sequence events, quantify the duration of events and the intervals between them, and compare the motions of objects. In this view, time does not refer to any kind of entity that "flows", that objects "move through", or that is a "container" for events. This view is in the tradition of Gottfried Leibniz and Immanuel Kant, in which time, rather than being an objective thing to be measured, is part of the mental measuring system.

According to John A. Wheeler, Princeton cosmologist, "Time is the most mysterious of the four usual dimensions of our space-time continuum. It's not so much that there's something strange about time, the thing that's strange is what's going on inside time. He continues, we will first understand how simple the universe is when we recognize how strange time is.

Einstein’s in his Special Theory of Relativity he united space and time into one entity - space-time. Within this new continuum, time slows down as you move faster, the time dilation effect.

So time can be viewed as both a psychological construction which we use to interpret our world and a mathematical kind of time, the most basic estimate of which is reflected on our watches and clocks. Also, the direction that time points to can be delineated by a number of physical and psychological phenomena.

• The Psychological Arrow of Time is our subjective sense of time, the fact that we remember events in one direction of time, the past, but not the other, the future.
• The Electromagnetic Arrow of Time as described by Maxwell's equations providing solutions to the propagation of radio waves, and light.
• The Cosmological Arrow of Time sees the history of the universe moving forward in time in an irreversible manner.
• The Thermodynamic Arrow involving the Law of Entropy, explaining the behavior that all the universe progresses from order to disorder