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What is Time?

There are few things that surround us every instant of our lives that remain so much a mystery as time. Is it a dimension? An immutable attribute of our existence? Or just an illusion? Can it run backwards? Can it proceed at different speeds?

A year or so ago, I was pondering the issue of the quantum uncertainty that surrounds photons and the mind-boggling issue of how the position of a physical particle can be best described by a probability wave, rather than being known with absolute certainty.

The concept of a wave of probabilities describing the position of an object seems so incongruous with the macro world in which we live. Or is it? We describe the location of a photon in terms of probabilities - it MIGHT be at location [x,y,z], but there is a probability it might also be at [x1,y1,z1], or might even be lurking on an outer star in the Andromeda galaxy, although the probability of that is....well, awfully small!

We are used to thinking of an object in just one place. Or are we? Suppose I ask you where you will be at 10am tomorrow morning? You might describe that in terms of probabilities - most likely you will be at your office sitting at your desk (most likely), but you might have overslept and still be in bed at home (a lesser probability), or you might have unexpectedly hopped a plane for a brief vacation in Bermuda (much less likely), or you might even be half your way to the moon, having stowed away on a shuttle mission (ok, VERY unlikely). Well.... hello, this is sounding an awful lot like the way we describe the position of that photon!  We have a set of probabilities of its location, but we won't know for sure until we observe that photon, thereby collapsing the quantum probability wave, and we won't know where YOU are until 10am tomorrow morning, at which point we will know for SURE where you are at that time. We could easily describe your expected location tomorrow at 10am in terms of a probability wave.

There seems to be an unusually coordinate relationship between time and the process of collapse of a quantum probability wave.

At that point a thought suddenly struck me: Perhaps time is the way in which we experience the progressive collapse of the quantum probability wave for the entire universe?

All objects have a quantum probability wave associated with them. For all practical purposes, we assume that the uncertainty does not exist on the macro level - I can see you sitting at your desk - I don't see a fuzzy probability wave associated with your presence that also includes your being at home. But when I take time into account, I suddenly realize that I DO see a fuzzy wave associated with your location over the extent of your existence.

How fast does a quantum probability wave collapse? It might be that the time it takes to collapse is the time it takes light to travel from one boundary to the other of the object in question. For a photon, that collapse appears to occur almost instantaneously due to the small size of the object, but for the entire universe which has been around for some 13-14 billion years, perhaps it takes 13 billion years for the quantum probability wave to collapse and we are sitting RIGHT within it as it is collapsing and continues to collapse. And because the universe is constantly expanding, the rate of collapse relative to the scale of the universe might even be constant so the wave will continue to collapse without any boundary in time.

And time itself may not be uniform across all geometries and scales - Maybe the quantum probability wave collapses at a uniform rate independent of geometry and scales and the only difference is that time is stretched or compressed, but because our methods of measuring time are inherently linear, we assume that there are different time scales associated with these events. Quantum entanglement suggests that time may be compressed to extraordinary degrees in some cases, so it appears that there may be shortcuts through other dimensions which allow the wave to collapse virtually instantaneously from our 3-dimensional perspective.

Can we travel backwards? No. And why not? Because the quantum probability wave is always collapsing - and that results in the universe moving toward a state of higher entropy as the measure of disorder is increasing as the wave collapses and new and different states become frozen into the historical fabric of the universe. Moments after the Big Bang, any given particle had only a short history of known states and positions behind it and a single, huge probabilistic future ahead. As the wave collapses, the history becomes larger and the future diminishes and so the number of frozen states at any instant of time is increasing - hence the increase in entropy.

Isolated systems always move towards states of higher entropy, not lower, and since the universe is the ultimate isolated entity, time does have an arrow associated with it.

On another note, I think the Greeks were right - there IS an indivisible object - too small to divide any further, only it wasn't the atom, it was the Planck Length - that's one of the reasons I prefer Loop Quantum Gravity over String Theory...

Comments? Think I'm nuts? No, don't bother telling me, I know it already, ok?    Email me at cesdewar@PimlicoSoftware.com

C. E. Steuart Dewar
Morganton, GA 30560 USA
December 26, 2005