The measure of the Universe

12th May 1995 at 01:00
SCHRODINGER'S KITTENS AND THE SEARCH FOR REALITY, By John Gribbin, Weidenfeld amp; Nicolson #163;18.99, 0 297 81519 9

Dennis Ashton examines a new theory of the nature of reality. When J S Haldane remarked that the Universe is not only queerer than we suppose, but queerer than we can suppose he may have been looking to the stars. But his sentiment applies equally to the sub-atomic quantum world, which in dimension is as far away from us as the galaxies.

John Gribbin puts it this way: "The quantum world operates on a scale as much smaller than a sugar cube as a sugar cube is compared to the entire Universe . . . people are about midway in size between the quantum world and the whole Universe - and we claim to be able to understand what is going on at both extremes."

Quantum physics demands thought experiments like Erwin Schrodinger's famous cat paradox involving a cat which according to standard quantum theory is dead and alive at the same time. Since writing In Search of Schodinger's Cat 11 years ago, John Gribbin has taken stock of the way in which some mind puzzles have recently been transferred into real experiments. Fresh insights have given birth to Schrodinger's Kittens in which Gribbin declares that "for the first time it is possible to say what quantum theory means". He takes us beneath the surface of everyday reality into a spooky microcosm to seek out that meaning.

The journey into the quantum world is expertly crafted. Gribbin first denies the central mystery of quantum theory through an experiment which exposes the problems arising from the wave-particle duality of photons and electrons. He argues that the standard interpretation of events - the Copenhagen Interpretation - is fatally flawed, It can describe and predict,but not explain.

To prepare the ground for a fresh interpretation, Gribbin pauses to describe the development of our ideas of the nature of light. The hero of quantum physics emerges as Richard Feynman, who is described as "the greatest theoretical physicist of our generation". Ultimately Gribbin's favoured solution derives from concepts generated by Feynman.

We return to the quantum scale to see how thought investigations are now being translated into real experiments by modern technology. Among them is one which infers that "beam me up Scotty" could become a real request - for electrons at least. The process is not quite pure Star Trek: it is "teleportation, Jim, but not as we know it".

Having brought the story of quantum experimentation up to date, Gribbin outlines current interpretations and the implications which arise from each.

He reminds us of the shortcomings in the present orthodoxy of the Copenhagen Interpretation: shortcomings reinforced by a recent experiment which shows a single photon acting as both wave and particle. A variation of the Copenhagen Interpretation "I think, therefore" implies that the Universe exists only because we are looking at it. This says Gribbin, is a "mystic path" along which the standard view can lead.

A completely different approach is taken by David Bohm, whose holistic view means that "everything is connected to everything else and affected (instantaneously) by everything else". This is set aside along with the "many-worlds" theory which is valued by Gribbin because of its connection with science fiction stories based on parallel universes.

After a short time out to consider scientific thinking and models Gribbin is ready to present the denouement - his favoured theory which he introduces as "a myth for our times". He brings together some of the elements with which we are now familiar to discuss the Transactional Interpretation championed by John Cramer.

Cramer explains a quantum event as a temporal "handshake" across space time. An electron, for example, sends out an offer wave into the future and into the past. This is picked up by an absorber electron which returns a confirmation wave: the events occur instantaneously to complete the quantum transaction. Armed with this model and an appreciation of the nuances of the transactional interpretation, we can explain the fate of Schrodinger's cat and Gribbin's kittens.

In our journey through the quantum underworld Gribbin has constructed a framework within which we can suspend ordinary common sense and approach strange quantum truths with an open mind. We emerge into the everyday world to find it less absolute, the universe is closer, somehow interconnected. Exposure to quantum reality may well alter our view of the macroworld which we inhabit. John Sandersin Haldane would surely have approved.

Dennis Ashton is director of Sheffield Stardome Planetarium.

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