David Bohm (1917–92) was a man of principle. He refused to denounce fellow members of the Communist Party in the US during the McCarthy era, and he insisted that physicists should search for an explanation of quantum phenomena when almost all physicists believed that none existed. Olival Freire Jr examines his life and work in a new biography, David Bohm: A Life Dedicated to Understanding the Quantum World.
David Bohm in 1949, shortly after he had refused to testify before the House Un-American Activities Committee.
David Bohm in 1949, shortly after he had refused to testify before the House Un-American Activities Committee.
Bohm’s was an eventful life filled with significant scientific achievements. His 1943 doctoral dissertation on the scattering of protons was classified because of its potential military value for the Manhattan Project, and his subsequent work on plasma physics is renowned for its use of collective variables and for the discovery of what is now called Bohm diffusion. But Bohm is perhaps best known for his work on quantum mechanics. In 1951 he published a textbook on the topic in which he defended the orthodox Copenhagen interpretation. He gave a copy to Albert Einstein, and in the ensuing conversation, Einstein convinced him that there was something fundamentally wrong with the Copenhagen view.
So Bohm broke up with Copenhagen. He immediately went to work on an alternative approach and came up with what is still the simplest and most baffling solution of the paradoxes of quantum mechanics. He proposed that electrons had trajectories and suggested an equation of motion. From that proposal, he developed a full theory that he called the causal or ontological interpretation of quantum mechanics, now often called Bohmian mechanics.
At the time, almost all physicists believed that the paradoxes of quantum mechanics simply could not be solved. Most of Bohm’s contemporaries opposed his theories and considered him a heretic. To make matters worse, Bohm also got into political trouble. After he refused to name other communists to the House Un-American Activities Committee, he was indicted for contempt of Congress, whereupon Princeton University terminated his contract. They refused to renew it even after Bohm was acquitted a few months later. As no other US university would hire him, he was effectively forced to leave the country. He moved first to Brazil, then a few years later to Israel, and from there to the UK.
Near the time of his move to the UK, he discovered the Aharonov–Bohm effect jointly with his student Yakir Aharonov; the effect demonstrates that the electromagnetic vector potential can influence the interference pattern of an electron’s wavefunction even if the field strength vanishes. Also around that time, despite the personal price he had paid for his loyalty to the Communist Party, he abandoned Communism after learning of the crimes of the Soviet government under Joseph Stalin.
Freire, a physicist and historian of physics at the Federal University of Bahia in Brazil, has written about the history behind quantum mechanics before: In his previous book, The Quantum Dissidents: Rebuilding the Foundations of Quantum Mechanics (1950–1990), published in 2015, he studied the growing interest in alternatives to the quantum orthodoxy, with chapters on Hugh Everett, Eugene Wigner, John Bell’s nonlocality theorem, decoherence, and also Bohm.
In contrast to an earlier biography by F. David Peat, Infinite Potential: The Life and Times of David Bohm (1996), which focused more on Bohm’s life, Freire is primarily interested in the content, development, and reception of Bohm’s scientific ideas. As a physicist himself, Freire dives into the scientific details of Bohm’s arguments with and reactions to his contemporaries, such as his responses to Bell’s famous theorem and the experimental tests of Bell’s inequality.
Freire meticulously works his way through a wealth of historical materials. The book includes quotations from letters and interviews and plots citation counts to help the reader visualize the impact of Bohm’s papers over the years. Freire’s declared goal is to depict his subject not as a hero or saint, but with all his contradictions, changes, and doubts. And that he does. For example, he describes how Bohm’s enthusiasm for Bohmian mechanics waned over the years, how lackluster his defenses of it were by the 1960s, and how his interest returned to it in the 1980s. Freire avoids passing judgment on the value of Bohm’s various ideas and approaches.
Readers will not learn Bohm’s theories from this book. Those who want to understand Bohmian mechanics in its modern formulation and its status compared to the orthodox Copenhagen interpretation would do well to consult Detlef Dürr and Stefan Teufel’s Bohmian Mechanics: The Physics and Mathematics of Quantum Theory (2009) or Jean Bricmont’s Making Sense of Quantum Mechanics (2016). For those curious about the story behind the theory and the struggles and breakthroughs of its pioneer, David Bohm is a rich resource.
Roderich Tumulka is a faculty member in the department of mathematics at Eberhard Karls University in Tübingen, Germany. His research focuses on mathematical physics, particularly on the foundations of quantum mechanics and quantum statistical mechanics.
