Tuesday, April 30, 2013

Grasping the universe, with mathematics


by Neil Turok,
Allen & Unwin, 294pp. 

To write a book about infinity is tough, and to review it is not easy either.

Few things that should interest us more than the basic questions about how we, and everything we know, came into existence.  Our oldest creation stories tried to describe the universe in the language and ideas available to our ancestors, mostly metaphors drawn from human experience.  Now we expect things to be explained in a language that can apply universally to the material world as we perceive it, without entirely negating the spiritual dimensions we infer as a means to fill the gaps in our understanding.

Uncomfortably for me and many others, that language is mathematics, as applied to the science of physics. Both these domains can be intimidating to many seekers after the truth, who are more accustomed to the floating worlds of emotion and intuition. Most will turn aside, which is a pity.
It was a bold decision for the producers of the Canadian Broadcasting Corporation's annual Massey Lecture series to commission Neil Turok in 2012.  Turok held a chair in mathematical physics at Cambridge and published, together with Stephen Hawking, a theory on how universes come into existence.  He now heads the Perimeter Institute in Canada, which supports the study of theoretical physics and campaigns for wider community understanding of what physicists are on about, and why it matters.

This book is the texts of those lectures. The Universe Within  is about the ways  human minds have grappled to understand the infinities and imponderables of all matter and energy, from smallest sub-atomic energy states to the possibly infinite multiplicity of universes that share time and space with everything we humans are able to observe.
 Broadcasting is strictly linear - you can't double back to re-hear a paragraph. You get it or your miss it. Turok does his best to catch the average curious mind  with anecdotes and colorful metaphors, but I have to wonder how many millions of polite Canadians could genuinely grasp what he was on about from beginning to end.  Even with the advantages of the book for, it was a tough read for someone with lifelong amateur curiosity into the general concepts of cosmology and physics.
 If you do follow Turok, you will end up accepting that our universe is expanding at an accelerating rate, having started as a microscopic dot of unbelievably compressed energy some 4-5 billion years ago.  The expansion is probably powered by unmeasurable "dark matter" and "vacuum energy".  It is not the job of physicists to ask why this happened, but they are increasingly confident that they know how it happened.  Turok inclines to the view that our current expanding universe is just one instance of an infinite number of expansions, followed after a few billion years by contraction, and then another Big Bang to start the expansion again.

A lot of this seems disconnected from human experience because mathematical reasoning is not the same thing as common sense. The greatest conceptual leap takes us from classical physics to the realm of quantum mechanics.  In this framework the  universe is in constant flux on many dimensions and there is no truth, only probability.  The job of physicists is to provide theories with reasonable probability.  As it happens, the chance of our own universe even existing is at a very low level of probability. However, because the number of possibilities is infinite, sooner or later our universe would be bound to pop up.  After the shock, probability actually makes more sense than certainty to the human brain.

Richard Thwaites has maintained a cautious interest in scientific cosmology since reading John Milton's Paradise Lost as a teenager.

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