Schrodinger's Rabbits: The Many Worlds of Quantum [Paperback]

This book is somewhat harder to read because the subject does not flow well from chapter to chapter, but on the positive side, it is written for a general reader which requires only basic knowledge of quantum physics. The author states that his main focus is the recent advances at Oxford University, due to Roger Penrose and David Deutsch, with emphasis on the many worlds interpretation of quantum physics. But as you read through the chapters his lack of focus becomes evident.

The summary of the book is as follows: Schrodinger's equations for an electron in an atom are described by the "time-inde¬pendent" equation, which does not answer the question of where the particle is located at any given instant. The time-dependent equation predicts that as long as it is not interacting with anything, the wave will flatten and spread out to infinity. Yet even a tiny observation-like interaction with this wave somewhere in the universe can bring an extremely point-like electron springing into view, with dimensions that remain too small to mea¬sure and this happens in less time than it would take light to cross the region of space where it was until a moment ago. It is hard to imagine any reasonable physi¬cal mechanism that could bring about quantum collapse (faster than speed of light).

The quantum phenomenon is interpreted by two major schools of thought; the Copenhagen interpretation due to Niels Bohr, and the many worlds interpretation due to Hugh Everett. According to the former, that unmodified Schrodinger wave equation gives rise to a collapsed single reality when perceived by a conscious observer, but it does not provide a mechanism for quantum collapse. Roger Penrose proposes that the Schrodinger wave equation must be modified to include some physical collapse mechanism that gives rise to a single-valued reality. Exponents of many-worlds interpretation propose that collapse never hap¬pens and the universe continues with all outcomes which are equal and real. Just believe what the equations (math) are telling us, that the universe is tracing out all possible histories, rather than just one privileged one expounded by Copenhagen school. There is one problem at the heart of the many worlds concept, which is how do you treat relative probabilities of different outcomes and the world lines that follow them? There is a third interpretation due to David Bohm (Bohmian mechanics) called hidden variables interpretation. The conceptual difficulties of the quantum world such as, the two-slit experiment, Heisenberg uncertainty, and the quantum col¬lapse is explained by postulating some fine struc¬ture to space that is too delicate to measure directly. This hypothetical fine structure also called hidden local variables. Waves that can influence the motion of both photons and matter particles and make small objects judder about so as to complicate the measurement of their positions and motions. Abrupt collision jolt particles from the waves they are associated with resulting in localization of matter (quantum collapse).

The spacetime in which the probability waves move is also quantized. If gravitational force (space-time curvature) were subjected to quantum fluctuations in the way that other fields and energies are, mathematical infinities would arise. In physical terms, the structure of space-time would be very un¬stable. A quantum fluctuation in a tiny region of space-time would very rapidly grow, perhaps spawning exotic entities such as black holes at a colossal rate. Roger Penrose offers an explanation by suggesting that such uncertainties in gravitational field energy tend to cancel themselves out producing quantum collapse as a side effect. Even two atomic nuclei attract each other gravitationally and produce tiny curvature in spacetime. Penrose's calculations for quantum collapse as expected is fast for larger objects (for a cat it is 10(e-37) seconds, and for a beryllium ion, 100 years).

The first half of the book is sometimes irrelevant and boring but the second half is interesting. I found the last three chapters are particularly interesting; it is here the author discusses the quantized spacetime and the information stored in space-time in relation to the rest of the universe. There are many books on quantum physics and physical reality written for general readers, and I recommend readers to look for other sources to strengthen their knowledge in quantum reality and philosophy of existence.

1. Physics Meets Philosophy at the Planck Scale: Contemporary Theories in Quantum Gravity
2. The Tao of Physics: An Exploration of the Parallels between Modern Physics and Eastern Mysticism: An Exploration of the Parallels Between Modern Physics and Eastern Mysticism: 25th Anniversary Edition
3. The Physics of Consciousness: The Quantum Mind and the Meaning of Life
4. What is Life?: With Mind and Matter and Autobiographical Sketches (Canto)
5. A Life of Erwin Schrodinger (Canto Original) (Canto original series)
6. SCIENCE AND THE HUMAN TEMPERAMENT
7. Self-Aware Universe: How Consciousness Creates the Material World
8. Schrodinger's Kittens and the Search for Reality
9. Physics and Philosophy: The Revolution in Modern Science (Penguin Modern Classics)
10. Niels Bohr's Times: In Physics, Philosophy and Polity

This is an exceptionally well-written book on why there are strong reasons for people to become "many worlders", accepting that multiple versions of themselves are branching into overlapping existence as the results of the escalation of quantum microscopic events. This philosophical outlook is shocking on many levels, and initially strikes people as absurd, but the reasons reviewed in this fine book should start to make people more open-minded to its possible reality.

The "Many worlds" idea initially arose from people trying to make sense of the philosophical issues of quantum mechanics. However it turns out that the really problematic issues arise, not from quantum mechanics itself, but from some celebrated experiments that have been carried out (by Alain Aspect and others), verifying what's known as the Bell Inequalities for spatially separated particles originating from a common origin. These experiments cry out for an explanation, independent of whatever mathematical formalism (quantum mechanics or anything else) is used to calculate the bafflingly strong statistical correlations observed in the results. As the book makes clear, there really is no easy solution to this problem.

The author has a pleasant writing style, mixing in detective story writing and references to science fiction stories, with analysis of philosophical ideas. There's no complex maths to surmount - though the reader will have to think carefully, going through various passages. (The effort is worth it!)

Unlike many books which seem to repeat the same few themes spread over many chapters, each chapter in this book introduces important new concepts - which is another reason why it's rewarding to read it.

It's a shame the book isn't better known. As I write this, the current edition of the Scientific American (Dec 2007) has a pretty good article in it, on the subject of the many worlds interpretation. The article commemorates the 50th anniversary of this interpretation first appearing in print - in the doctoral thesis of Hugh Everett III. The SciAm article lists some useful pointers to further reading - including "The Fabric of Reality" by David Deutsch, which is another book that I thoroughly recommend. But alas, there's no mention of Colin Bruce's book.