As I write this sentence, it's 11:09 am on Sunday, September 20, 2009 CE – at least it was a few seconds ago. Ask me what time it is and I can give a fairly precise answer. But ask me what Time is, and things get a little fuzzy.

Time is money. Time waits for no man, and no man (or woman) ever has enough of it. Richard II wasted time, and then it wasted him. But what is “Time” exactly? That is a question we have difficulty answering outside of art and metaphor. In his Special Theory of Relativity, Einstein revealed that Time and Space are intimately related in a marriage called SpaceTime. In this scenario, the universe is characterized as having three dimensions of space. But what of time? Because objects move through space and, in a manner of speaking, also move through time,* it was simply tacked on as an additional “fourth dimension” – even though time is manifestly different from space. That has now become problematic with the theoretical discovery via string theory and M-theory of possibly as many as seven additional dimensions of space. What is time now – the 11th dimension?

This conundrum illustrates one of the secrets of physics: many of our accepted descriptions of the universe are artificial, human-imposed conventions designed to help us better understand the universe and our place within it. Space, after all, just is; it doesn’t divvy itself up into 3 or 4 parts like a sliced tomato. Dimensions are a contrivance we overlay onto Space in an attempt to make it more understandable and the behavior of things in it more predictable.

And for the most part such conventions work pretty well, although there remain many mysteries to torment us.

Time seems to be particularly confounding. Austrian physicist and philosopher Ernst Mach suggested that it doesn’t exist at all, but is simply “an abstraction at which we arrive through the changes of things.”(1) Also characterizing it as change, Julian Barbour suggests the apparent passage of time may be nothing but a very well founded illusion.(2) Physicist/cosmologist Carlo Rovelli postulates that Time emerges only as a statistical effect in the macroscopic universe but has no relevance to the world of quantum reality.(3) All of us have vague notions about Past, Present and Future, and we have well-defined conventions dividing Time into measurable and functional seconds, minutes and years. Time may or may not exist, but humans created the minute. But Time is difficult to see, touch or hold, so exactly what it is and how it works are clouded in mystery. Perhaps Time merits its own collection of dimensions, roughly analogous to the dimensions of Space. I don’t know that yet another convention will help us understand Time any better, but it does seem to follow naturally from the dimensionality of Space.

The three spatials dimensions are generally characterized as length, width and depth. However, they might more accurately be described as:
1st: length
2nd: length + width
3rd: length + width + depth

The three temporal dimensions might be loosely characterized as:
1st: (temporal) length
2nd: length + distance (or separation)
3rd: length + distance + entropy (or both processes of entropy and organization)

Here’s how it works:

The first dimension of Space is a line; the first dimension of Time (1-T) is also linear. It’s what we normally refer to as the “Arrow of Time.” Like a line, it has length but not width or depth. It stretches forward into the future and back into the past. All things in the universe flow along this Arrow of Time just by existing, and 1-T is essential to the existence of any entity. Another common name for 1-T is "history." It is the history of anything that exists.

There is a zero dimension of space, commonly called a “point,” having neither length, width nor depth. There is also an analogous zero dimension of time – it is as common to speak of “a point in time” as it is to reference a point in space. Another way to look at it is that 0-T is the Present, the eternal Now that slides along the Arrow of Time. An instant without temporal length, width or depth, it nevertheless has an obvious reality-conferring relationship to the three spatial dimensions. (Paradoxically, 0-T is that aspect of Time we think of as “reality.” After all, the past isn’t real – it only used to be. And the future doesn’t exist – it only has the potential to become real. While our intellect can grapple with the notions of past and future, our consciousness can only grasp and operate in the “Now.” Only Now, the zero dimension of Time, has an actuality, the quality of “realness.”)

Whereas 1-T represents a single entity’s flow through history or change in position along the Arrow of Time, 2-T is the time it takes the entity to move through space. It’s what we are referring to when we say it takes 6 hours to travel from Point A to Point B. The 2nd dimension of Time is a function of both velocity and distance in space. 1-T has no intrinsic correlation to spatial distance, but 2-T is part of the very fabric of space, essential and implicit in the notion of separation in the spatial dimensions. In fact, there could be no such thing as distance in space without this 2nd dimension of time, without the time it takes to go from one point in space to another. 2-T is also an essential function of velocity (the t in the V = d/t equation).

It is important to understand that position and movement in space is relational. That is, there is no background canvas of space on which an object’s position can be fixed. Relativity Theory explains that an object’s position in space is defined by its relationship to other objects in space. Therefore, movement through 2-T involves not just the spatial movement of one object, but also the change in relative position between it and other objects in space. 2-T characterizes the relationship between two or more entities and represents a change in their relationship in space as both change their positions in 1-T time. And since it is unlikely that any two objects move through space at exactly the same speed, they also move through time at different speeds.** Put the two together and 2-T becomes the change in the relationship of entities in SpaceTime.

As 1-T stretches forward and backwards in Time, 2-T stretches in two “directions” – through history as it also moves through space. To understand the third dimension of time, it’s helpful to think of how we envision 3-dimensional space. Start with a line (an infinite number of points set in a row). Now add an infinite number of lines set side-by-side to form a 2-dimensional plane. Pick any line anywhere in that plane as an axis. Rotate the plane completely around that axis and you create 3-dimensional space. Just as 3-D space becomes the sum total of the other spacial dimensions, 3-T is the sum of all the temporal dimensions. 2-T “moves” through space and through 1-T. Add up all of the 2-T manifestations and you fill out 3-T just as the sum of 2-dimensional space fills out the third dimension. In a nutshell, 3-T is the Time a closed system takes to go from maximum organization to maximum entropy. Stepping outside the phenomenon – viewing the universe from outside, as it were – one could say 3-T goes from entropy to organization as well.

Like any sustainable marriage, the unification of space and time has to be roughly a co-equal relationship. While they are undoubtably different elements of reality, there is no reason to believe that one aspect of the SpaceTime continuum is less complex than the other. We easily segment time into minutes and months just as we segment space into meters and miles. Why not then also divide time into dimensions? We can start with the four temporal dimensions (counting 0-T) that are analogous to the known four dimensions of space (including the zero dimension). If the additional dimensions of space theorized by string theory and M-Theory emerge as reality, perhaps we’ll also discover even more dimensions of time. What we then make of these discoveries, only time will tell.