The Quantum Moment: How Planck, Bohr, Einstein, and Heisenberg Taught Us to Love Uncertainty

Robert P. Crease and Alfred Scharff Goldhaber. W. W. Norton: 2014.

9780393067927

Quantum theory is the most accurate and precise description of the molecular, atomic, sub-atomic and sub-nuclear realms ever devised. It is also utterly exasperating. To anyone tutored in the language and the logic of classical physics, it is mathematically challenging, maddeningly bizarre and breathtakingly beautiful. As charismatic US physicist Richard Feynman warned: “Nobody understands quantum mechanics.”

Credit: Illustrations by Darren Hopes

Given its recondite nature, quantum weirdness has entered popular culture in remarkable ways. What might otherwise have been the preserve of dry academic texts and stuffy scientific conferences has become common currency. Who hasn't heard of Heisenberg's uncertainty principle or Schrödinger's cat? Quantum ideas of space, time and matter inspired British artist Anthony Gormley's vast, enigmatic steel sculpture Quantum Cloud near London's O2 arena. And UK-based dramatist Tom Stoppard's 1988 play Hapgood blends the duality of the double agent with a quantum duality in which matter and light are both waves and particles. Both of these works are cited in The Quantum Moment, in which philosopher Robert Crease and physicist Alfred Goldhaber explore quantum theory's enduring cultural impact.

Based on a class that the authors have taught for six years at Stony Brook University, New York, the book asks why quantum theory carries such a metaphorical punch — “wild and mysterious, packed with creative force” — and why it seems to be rediscovered in every generation. The authors' tale is structured along approximately linear historical lines, from Max Planck's discovery in 1900 that light can be described in terms of discrete 'bundles' of energy (quanta) to Bell's theorem, which opened the door from the 1960s onwards to some extraordinary experimental tests of the nature of our physical reality. Each chapter explores how some of the core ideas and principles that sprang from these historical moments have been absorbed into (inevitably mostly US) popular culture. This makes for an entertaining read, even for those already familiar with the story.

As Crease and Goldhaber explain, much of the impact on modern culture derives from what quantum theory has to say about the nature of reality. Arguably, centuries of observation, experimentation and strenuous intellectual endeavour were founded on scientists' expectation that the material world is composed of some kind of fundamental atoms of 'stuff'. Quantum theory, however, has rewarded these endeavours with phantom particles that, like waves, can be both here and there; a theoretical structure that tells us only what might happen (not what will); and quantum systems seemingly connected over great distances, giving rise to extended, non-local effects, or what Albert Einstein called “spooky action at a distance”.

Einstein famously rejected the element of chance that lies at the heart of quantum theory, declaring that God does not play dice. He argued that quantum theory is not complete. Those scientists who, like Einstein, are less inclined to accept that we have reached an ultimate limit of what is knowable remain firmly in denial. So, in the past 40 years or so, the efforts of agents provocateurs such as John Bell and Tony Leggett have encouraged an orgy of sophisticated laser-based experiments to test the foundations of quantum physics — what I have elsewhere called “experimental philosophy”. It is this work that has prompted the current interest in quantum cryptography, quantum computing and the teleportation of photons.

I have only one quibble with The Quantum Moment. Crease and Goldhaber support their narrative with 'interludes' after each chapter, designed to provide technical details, including some equations. The exposition here is a little drier than in the main chapters, but does not need to be. The material also necessarily repeats much of what has already been covered, which can become a little tedious. The authors suggest that readers might prefer to skip these interludes; for linear readers like me, that does not really work.

Those versed in quantum theory's practical applications might be tempted to dismiss its many manifestations in popular culture as what the authors call “fruitloopery”. And certainly, there is a lot of nonsense out there. But, as Crease and Goldhaber make abundantly clear at several points, many esteemed physicists (who should probably know better) have been more than willing to indulge their inner metaphysician in research papers and popularizations on the mistaken principle that, as the Canadian philosopher Marshall McLuhan once put it, “mud sometimes gives the illusion of depth”.

Thus we smile at the comical pronouncements on physics by US actress Shirley MacLaine, until the authors point out that she could be paraphrasing similar pronouncements made 55 years earlier by the British physicist James Jeans. I have elsewhere argued that contemporary theoretical physics has become rather self-indulgent and self-referential, a malaise that I have called fairy-tale physics. Deep questions about the nature of reality tend to provoke this kind of response, and it surely finds its origin in the quantum moment.