by Tessa Dick

Created on: May 09, 2009

Times marches on, flows like a river and takes us from the past through the present to the future. Yet time is an illusion, a mental construct which we employ to organize our lives. We remember the past and look forward tot he future, but sometimes the experience of a moment causes us to question whether we really know what time is. For example, sometimes we find ourselves struck by the feeling of deja vu, as if we were remembering the future. This and other experiences point to the fluid nature of time.

We measure time with clocks, watches and calendars, but our subjective experience of time contradicts the orderly measurements upon which we rely. For example, a child finds ten years an eternity, while a senior citizen finds a decade to last only for a fleeting moment. If you have ever been in a car crash or other frightening experience, you probably found things slowed down, as if time itself had nearly stopped. But when you had a similar physical experience on a roller coaster or other carnival ride, it lasted for an all too brief moment. The ticking clock might measure these two experiences as lasting the same amount of time, but we experience one as brief and the other as long lasting.

Sometimes I think that time does not exist at all. Einstein defined time as the fourth dimension, after the spatial dimensions of ;length, width and height. But what is a dimension, other than a mental construct for imposing order upon our world? When I toss a pair of dice, which dimension is the height? Of course the height is up and down, vertical, but the dice could have landed with different numbers showing on top. In other words, the dimension that we define as height is not fixed - it depends upon which way the dice fall, or upon how we look at those dice. The same can be said of length and width. We usually define the length as the long side, and the width as the short side, but what if the shape of the object changes, such as when you squeeze a lemon? Or in the case of the dice, the length and width are equal, so our designation of those dimensions is entirely arbitrary.

Time itself is an entirely arbitrary measurement of our movement in a dimension that we cannot see, but which we can measure with clocks, watches and calendars. It proceeds from the relative motion between two or more objects. If everything in the universe stopped moving, time would cease to exist. Fortunately, that is not likely to happen within my lifetime.

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