Time for the hard questions

Marcus Chown, contributor?

In About Time, astrophysicist Adam Frank makes the case that our concept of cosmic time is inextricably linked to our notions of human time

TIME, like a slippery eel, is nigh on impossible to pin down. Even our most cherished ideas about it cannot be correct. How, for instance, can there be a "flow" of time? For something to flow it must move with respect to something else - like a river against a riverbank. For time to flow, there would have to exist a second type of time.

Adam Frank, an astrophysicist at the University of Rochester, argues that our ideas of human and cosmic time are interwoven, and that science has come to the edge of a precipice where, forced to confront the question of "What happened before the big bang?", it must also ask, "What exactly is time?". As Frank shows in detail in About Time, some brave souls have already made the leap.

Those seeking a quantum theory of gravity know that at super-high energies, like those believed to have occurred in the earliest moments of the big bang, time loses all meaning. It cannot then be a fundamental property of reality but merely a feature that "emerged" from some deeper, non-temporal realm. Independent theoretical physicist Julian Barbour goes so far as to suggest time does not exist and has shown that the laws of physics can be perfectly well expressed without reference to it.

The theory of cosmic inflation - which suggests the constant, exponential expansion of the vacuum - posits that the big bang was not a beginning at all. This in turn has spawned the multiverse theory, in which our universe is just one among an infinity of universes in the eternally inflating vacuum. Cosmologist Andreas Albrecht at the University of California, Davis, believes that in such a cosmos it is impossible to define time uniquely at all; there are an infinity of times which spawn an infinite number of possible laws of physics.

Beyond exploring these mind-bending theories, I should say that the bulk of Frank's book is a fascinating and comprehensive survey of how technology - from farming to railways to telegraphy to the internet - has changed our everyday concept of time. He is excellent at showing how our ideas of human and cosmic time have evolved hand-in-hand. But in his telling of that tale, I think there is a warning for physicists: beware of what Carl Sagan called "temporal chauvinism". This is exemplified by the Victorians, who, living in the steam-powered world, thought the sun was a giant lump of coal, and even today's scientists, immersed in an information-processing world, sometimes think of the universe as a giant computer.

Frank's thesis that our notions of cosmic and human time are braided together is compelling. And there is no doubt that these ideas are being transformed yet again by the connected world we live in as we start to tackle these ultimate questions. No one can tell how the construct we use to make sense of our world - and our universe - will be revolutionised in the next few years. But, as Frank says, these are certainly exciting times.

Book Information
About Time
by Adam Frank
Published by: Simon & Schuster
$26

Source: http://feeds.newscientist.com/c/749/f/10897/s/190424f0/l/0L0Snewscientist0N0Cblogs0Cculturelab0C20A110C10A0Ctime0Efor0Ethe0Ehard0Equestions0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fonline0Enews/story01.htm

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