Nothing is more fundamental than the feeling that time passes: Hide the clocks, dim the lights, sit perfectly still – and yet time keeps slipping by (or seems to, at least). You might expect that modern physics, after 400 years, would have something profound to say about the apparent “flow” of time. Surprisingly, it does not – and this, in Lee Smolin’s view, is its great failing. Even worse, our best theories suggest that time’s passage may be, as Einstein once put it, “a stubbornly persistent illusion.”
Some are willing to live with this state of affairs, counter-intuitive as it may be. But Smolin, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., believes a new approach is in order. He doesn’t use the phrase “paradigm shift,” but that is, in effect, what he’s calling for.
Perimeter is famous for nurturing thinkers who challenge the status quo, and Smolin has reputation for doing just that. His first book, The Life of the Cosmos, presented a provocative new approach to cosmology, applying a Darwinian-style process of natural selection to the creation of universes, while The Trouble with Physics rankled string theorists by suggesting their field was likely to prove a dead end. Time Reborn is the result of his most ambitious quest to date: He wants to get time flowing again.
Ironically, the breakthrough that established modern physics in the first place may have been its first misstep: The introduction of mathematics into physics began four centuries ago with the work of Galileo and Descartes, and culminated with Newton’s Principia. As Smolin points out, the mathematics available to Galileo was already available to ancient Greeks, but they were content to keep math and physics separate. Why? This question, Smolin says, raises issues that are easy to state but fiendishly difficult to answer: “What is mathematics about? Why does it come into science?” (Deep questions indeed – and we are only on page 7!)
Before long, Newton’s approach had triumphed: Laws of physics were presumed to be mathematical laws, timeless and eternal. And here lies the problem: By virtue of being timeless, such laws give short shrift to time itself. They ignore “the seemingly most essential aspect of our existence in the world – its presentation to us as a succession of present moments.”
The 20th century gave us relativity and quantum theory, but these only entrenched the “timeless” view more deeply. Einstein’s four-dimensional space-time is like a static “block” in which nothing actually happens: Past, present, and future are all there, but without direction or flow. Nothing in this picture of the universe explains how one instant succeeds another.
Smolin does not have the whole answer – but he believes he has a starting point. In the first part of Einstein’s theory, known as special relativity, every reference frame is seen to be equivalent; the laws of physics are the same for everyone. (In the second part of his theory, general relativity, Einstein develops a link between gravity and the geometry of space-time.) But Smolin believes that there is, in fact, a preferred frame of reference, linked to the evolution of the universe as a whole (which he calls “preferred global time”). He asserts that there really is “a single rate at which time flows,” a rate that is the same throughout the universe. He stresses that this isn’t a refutation of Einstein’s theory, just a reformulation. But it brings a big payoff: “Time has been rediscovered.”
A key ingredient of this reformulation is something called “shape dynamics,” formulated by British physicist Julian Barbour (author of The End of Time) and further refined in the past few years by three young researchers at the Perimeter Institute. I won’t try to explain shape dynamics here, but its appeal, Smolin says, is that it saves time from Einsteinian oblivion. (Incidentally, Barbour’s view of time is very different from Smolin’s – a case of two extraordinarily bright physicists tackling the same problem but reaching sharply divergent conclusions.)
There is more in Time Reborn: Hints of a new approach to quantum theory, for example; and, toward the end, an acknowledgment that the problem of consciousness may be every bit as challenging as the problem of time (to which it may be connected).
I’m not sure how much of this will stand the test of (sorry!) time. Paradigms do not shift easily, and for good reason. But it is incumbent upon us to occasionally step back and challenge our assumptions; to ask the very deepest questions we can articulate about the nature of the universe and our experience of existing within it – and, when possible, to put those ideas into words that a layperson can (with some effort) follow. Smolin is one of just a handful of thinkers who is up to that challenge.
Considering the esoteric nature of some of the material being presented, Time Reborn is relatively jargon- and equation-free. There are some challenging concepts, but nothing to deter the lay reader. (Smolin has said that he’s also working on a more technical book on the same subject, to be co-written with philosopher Roberto Mangabeira Unger.)
I hope this is the start of an exciting new chapter in theoretical physics. But I fear that Einstein was right, and that the ultimate explanation for time’s apparent flow might come from the realm of psychology or neuroscience rather than physics. Science, after all, has a track record of overturning our “common sense” beliefs about the world. Again and again, things that were “obvious” – that the sun revolves around the earth; that humans are fundamentally different from other animals – have been shown to be artifacts of an anthropocentric worldview. Maybe the “obvious” passage of time is another of these illusions.
Dan Falk is a Toronto-based science journalist. His most recent book is In Search of Time: Journeys along a Curious Dimension.