2007-03-21T04:05:00.000-07:00

Two distinct views exist 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 Sir Isaac Newton subscribed, in which time itself is something that can be measured.

The Oxford English Dictionary defines time as "the indefinite continued progress of existence and events in the past, present, and future, regarded as a whole." The American Heritage Dictionary defines time as "a nonspatial linear continuum in which events occur in an apparently irreversible succession." Encarta, Microsoft's Digital Multimedia Encyclopedia, gives the definition of time as a "System of distinguishing events: a dimension that enables two identical events occurring at the same point in space to be distinguished, measured by the interval between the events."

Is time a 'real' dimension?
The Big Bang theory describes how the universe was created from the Big Bang singularity, where all matter and space is contained in a single point of infinite density. At the moment of creation of the universe - the Big Bang - all matter, space and time came into existence, before that time did not exist. Our universe could not exist without time, and time could not exist without the universe, they are different components of the one entity.

Space-time:
A term used to denote the geometry of the physical universe as suggested by the theory of relativity. It is also called space-time continuum. Whereas in Newtonian physics space and time had been considered quite separate entities, A. Einstein and H. Minkowski showed that they are actually intimately intertwined.15
According to general relativity, 'space' is just another name for the gravitational field of the universe. As such, we stand in relation to space what photons of light stand in relation to the electromagnetic field. Space is just another physical field in nature, and at its smallest scales, it dissolves away into some kind of quantum 'haze' where our ideas of time and space no longer have much meaning.

According to Einstein's theory of relativity, time is regarded as a fourth dimension, on an equal footing with the familiar three dimensions of space. Einstein says that you can imagine all of space and time represented as a four dimensional space-time map, on which all of history, the present and the future of the universe can be represented. The four dimensions of space and time are collectively referred to as the space-time continuum, which by the way, is not just an invention from the script writers of Star Trek.

The problem we have is in trying to visualize these four dimensions because we can only see the three dimensions of space, we cannot 'see' time. However, even though we cannot see it, it is necessary to include time if we are required to define a precise location. We can, for example, define an object's position in a room by three simple measurements, such as how far forward, how far to the left and height above floor level. These co-ordinates will define where the object is, but only where it is now, it may be somewhere else tomorrow.

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Time and space effect