SCIENCE: Faust in Copenhagen: The Struggle for the Soul of Physics and the Birth of the Nuclear Age By Gino Segrè:In 1926 Albert Einstein made his famous proclamation that God "does not play dice", writes Michael John Gorman.
Einstein's remark expressed a deep dissatisfaction with the counter-intuitive consequences of the revolutionary new science of minute particles known as quantum mechanics.
According to quantum mechanics, if you repeat exactly the same experiment a number of times under exactly the same conditions you can get very different results, and even a God-like physicist possessing perfect information about the state of the entire universe could only tell you the probabilities of different outcomes occurring. Einstein was not particularly religious. His "God" - "the Old One" as he sometimes called him - was the underlying order he found in nature itself. He was extremely disturbed by the idea that nature was susceptible to the caprices of chance, and did not evolve in an inexorable, predictable manner.
Many physicists even now dismiss Einstein's unwillingness to embrace the consequences of quantum mechanics as a symptom of his being "over the hill" and unable to accept new ideas. As Einstein was only 47 years old when he made this announcement this may sound peculiar, but a humbling feature of this defining moment in the development of 20th-century physics was that the major players tended to carry out their most original work when they were under 30.
Einstein himself had published both his Special Theory of Relativity and his fundamental discovery of the photoelectric effect at the age of 26. Rather than disparaging quantum mechanics, in which he was deeply involved from the outset, Einstein appears to have been convinced, like many physicists after him, that the probabilities predicted by the formulae were not the end of the story, that they were merely the manifestation of some still unknown micro-laws of physics that were fully deterministic.
Quantum mechanics is a tremendously important but profoundly strange theory and many of the paradoxes and thought experiments associated with it have acquired their own cultural currency. Schrödinger's Cat describes a diabolical imaginary experiment in which a cat is sealed inside a box containing a deadly poison triggered by a quantum device. The device has a 50% chance of detonating in a given time period and killing the cat. If someone opens the box after this time has elapsed, we would expect him or her to see either a dead cat or a living cat.
According to the standard "Copenhagen" interpretation of quantum mechanics, however, until the box is opened, the cat exists simultaneously in both alive and dead states. It is only when the person sees the cat that this hybrid dead-alive cat suddenly jumps into being either a dead or a living cat.
Where the classical physics of Newton had suggested that the universe was a system of billiard-ball like particles colliding and moving in space according to completely deterministic laws, quantum mechanics posited a radical shift in perspective. Like the Copernican revolution which challenged the position of humanity at the centre of the universe, the quantum revolution suggested that the observer changed the external world through the very act of observation. Small wonder then that quantum mechanics has been invoked by all manner of literary critics and postmodernists as a demonstration of the non-existence of an absolute external reality, often in ways that demonstrate limited awareness of the precise mathematical laws at its heart. In spite of its bizarre and sometimes paradoxical consequences for our understanding of the world around us, in terms of sheer predictive power, quantum mechanics is a theory that ranks along with Einstein's relativity, Newton's theory of gravitation and even Euclid's geometry as one of the most successful physical theories of all time.
Physicists are still today struggling to unify quantum mechanics with Einstein's General Theory of Relativity through the development of a convincing theory of quantum gravity, a holy grail of contemporary theoretical physicists. Without quantum mechanics, the development of lasers and electronics would have been impossible. Even now quantum mechanics is at the heart of new developments in nanotechnology, rich in promise of all manner of life-altering innovations.
GINO SEGRÉ'S BOOK dwells on the heady moments characterising the emergence of quantum mechanics, and the subsequent early developments of nuclear physics in Copenhagen in the 1920s and 1930s. The book takes as its point of departure a tongue-in-cheek performance of Goethe's Faust staged by many of the key physicists involved in the development of the new theory at the Atomicum, Niels Bohr's research institute in Copenhagen in 1932. The Faustian bargain of the particle physicists, particularly in light of the later development of nuclear physics and its serious consequences in the development of the atomic bomb, provides a literary fulcrum for Segrè, himself a practising physicist and newphew of Nobel Laureate Emilio Segrè. The book uses the Copenhagen Faust performance to introduce us to the lives of seven key figures in the development of quantum mechanics and nuclear physics: Niels Bohr, the father figure of quantum mechanics, constantly engaged in Socratic dialogue with his many apprentices; the experimentalist Lisa Meitner, who appallingly never received the Nobel prize for her extraordinary work with Otto Hahn on nuclear fission; Paul Dirac, who managed to conjoin Einstein's Special Theory of Relativity with quantum mechanics; Wolfgang Pauli, nicknamed the "wrath of God" for his acerbic wit and better known for his Exclusion Principle than for the remarkable psychoanalytic sessions he undertook with Karl Jung that led to the development of the Jungian concept of the "archetype"; Werner Heisenberg, best known for the often misconstrued Uncertainty Principle which established limits on what one could know precisely about the state of the world at any one time, Paul Ehrenfest, who bridged statistical and quantum mechanics before succumbing to depression and shooting himself and his youngest son, and, finally, Max Delbruck, the rather more humorous author of the Copenhagen Faust-skit, who also played a key role in developing the new field of molecular biology.
Any one of these figures would be prime material for an intellectual biography, and here is the book's primary challenge - collective intellectual biography is an extremely difficult business. Where the book fails in terms of providing a powerful narrative, torn between the pivotal "moment" of 1932 Copenhagen and the tale of the evolution of nuclear physics from quantum mechanics, it succeeds in conveying the extraordinary social environment orbiting around Neils Bohr in 1920s and 1930s Copenhagen.
As in Michael Frayn's electric 1998 play Copenhagen, which focuses on the troubled relationship between Bohr, a half-Jew, and Heisenberg, the brilliant German apprentice in charge of the Nazi nuclear programme, Bohr is the most fascinating character here. By creating a fertile intellectual climate, Bohr engendered a new science through a particular style of conversation. While Bohr's model of the orbits of the electron in the hydrogen atom is known to any high school physics student, Bohr's key influence was not exerted through his own discoveries, but rather through the way he worked as a facilitator, mentor, questioner and catalyst to the discoveries of others. Einstein remarked that Bohr uttered opinions "like one who perpetually jousts about and never like one who believes he holds the whole defining truth". The climate produced by Bohr was full of schoolboy pranks and childish taunts, a sense of collegiality and intense intellectual competition. Where Frayn's remarkable dramatisation of the Bohr-Heisenberg conversations maintains extraordinary tension and intensity as we unravel the extent of Heisenberg's involvement in the development of a bomb for the Germans, Segrè's book, informed by a deep professional understanding of the physics, starts from a promising Faustian premise but commits the error of trying to tell us too much, becoming occasionally lost in biographical trivia and academic genealogy that take away from the literally earth-shattering subject matter at its heart.
Michael John Gorman is director of the Science Gallery at Trinity College Dublin
Jonathan Cape, 310pp. £20