The Speculist

Farewell to Time

On this New Year's Day, why should we be content merely to say goodbye to the year just ended when we can say goodbye to the notion of time itself?

Brian Greene pens a lengthy op-ed in today's New York Times on the nature of time, and how our understanding of it has changed. According to Greene, our understanding is likely to change even more in the years to come:

Today's scientists seeking to combine quantum mechanics with Einstein's theory of gravity (the general theory of relativity) are convinced that we are on the verge of another major upheaval, one that will pinpoint the more elemental concepts from which time and space emerge. Many believe this will involve a radically new formulation of natural law in which scientists will be compelled to trade the space-time matrix within which they have worked for centuries for a more basic "realm" that is itself devoid of time and space.

This is such a perplexing idea that grasping it poses a substantial challenge, even for leading researchers. Broadly speaking, scientists envision that there will be no mention of time and space in the basic equations of the sought-for framework. And yet — just as clear, liquid water emerges from particular combinations of an enormous number of H20 molecules — time and space as we know them would emerge from particular combinations of some more basic, though still unidentified, entities. Time and space themselves, though, would be rendered secondary, derivative features, that emerge only in suitable conditions (in the aftermath of the Big Bang, for example). As outrageous as it sounds, to many researchers, including me, such a departure of time and space from the ultimate laws of the universe seems inevitable.

The notion of describing the operation of the universe without reference to space or time put me in mind of Julian Barbour's The End of Time, a book which purports to do that very thing. Barbour describes space and time emerging as a waveform through a vast configuration space that contains what we might think of as perfect 3D still-life renderings of the universe. Every possible configuration of the universe exists in this space, and we might be tempted to think of time as stop-motion animation. Experiencing the configurations sequentially creates the illusion of the passage of time (and of motion, which Barbour also claims doesn't really exist, at least not the way we think it does.)

These stop-motion frames start to sound a little like the flip-book picture of time that Greene refutes in his op-ed:

For example, if you and I were sitting next to each other, our freeze-frame images of the present would be identical. But were you to start walking, the mathematics of relativity shows that the subsequent pages of your flip-book would rotate so that each one of your new pages would angle across many of mine; what you'd consider one moment in time — your new notion of the present — would include events I'd claim to have happened at different times, some earlier and some later.

Greene's objections to a stop-motion universe are well-taken when applied to a literal freeze-frame model, although I don't think that's exactly what Barbour proposes. The freeze-frame imagery is just a handy way to visualize the ideas in approximation. I'm pretty sure that Barbour wouldn't approve of my stop-motion animation analogy, relying as it does on some notion of an external clock. In Barbour's model, there are no clocks and there is not time, nor space (as we think of it) nor motion. These are all "optical illusions" that derive from the clustering of more and less probable configurations within the configuration space.

The problem with adopting this kind of model is that it flies directly in the face of experience. It will require an enormous change of perspective — bigger even than when Galileo told us that the sun doesn't actually rise or set — for us to accept the idea that time doesn't really exist. Still, whether through Barbour's model or some other, Brian Greene seems quite convinced that this is a change of perspective we will all eventually have to make.

What better time to start could there be than the beginning of a new year?