Questions and answers with A. Douglas Stone

In Einstein and the Quantum: The Quest of the Valiant Swabian (Princeton University Press, 2013), author A. Douglas Stone “argues that the creation saga [of quantum theory], as commonly narrated, seriously understates the immense breadth and depth of [Albert] Einstein’s contributions.” So writes MIT atomic physicist Daniel Kleppner in his April 2014 review of the book. Due to its provocative thesis, and Kleppner’s unequivocal endorsement, Einstein and the Quantum is featured in the 2014 “Year in Reviews” post on Bookends . It won the 2014 Phi Beta Kappa Award in Science and was selected as a top science book of 2013 by National Public Radio.

Stone is the Carl A. Morse Professor of Applied Physics and Physics at Yale University. He received his bachelor’s degree in social studies from Harvard College in 1976 and a second bachelor’s in physics and philosophy from Balliol College (Oxford University), where he was a Rhodes Scholar. Stone obtained his PhD in theoretical condensed-matter physics from MIT in 1983 and did postdoctoral work at IBM’s Thomas J. Watson Research Center in Yorktown Heights, New York, and at the State University of New York at Stony Brook.

Early in his career, Stone’s research focused on problems in mesoscopic electron systems and quantum fluctuations. For the past decade he has focused on optics, specifically on microcavity optics and laser physics. In January 2015 he will be presented with the Willis E. Lamb Award for Laser Science and Quantum Optics. He is a fellow of the American Physical Society and the Optical Society and an honorary member of the Aspen Center for Physics.

Physics Today recently caught up with Stone to discuss Einstein and the Quantum.

PT: Many books have been and probably will be written about Einstein. What does your book offer that the rest don’t?

Stone: Remarkably, I discovered somewhat accidentally in 2004–5 that there was a rather large gap in the literature on Einstein’s science. While there were a number of excellent articles and books by eminent historians of science focusing on Einstein’s seminal contributions to quantum theory, no author had attempted to synthesize this literature in a book that both contained the full scope of his contributions and was accessible to science enthusiasts without advanced technical training.

This is what my book offers, along with, I hope, an engaging narrative style and an alternative biographical sketch of Einstein’s life between 1896 and 1926. When one lays out Einstein’s accomplishments, starting from the photon concept in 1905 and ending with the quantum theory of ideal gases in 1924, and adds in the critical role he played in stimulating the work of Louis de Broglie and Erwin Schrödinger, one justifiably begins to regard him as the primary author of the modern theory. This is not a common perspective in most writing on Einstein and quantum mechanics, which tends to focus on his ultimate rejection of the theory and his critique of it through the EPR [Einstein-Podolsky-Rosen] paper.

PT: Why do you think Einstein’s role in quantum theory has been underappreciated?

Stone: I find it fascinating that the work of the greatest scientist of the 20th century could be undervalued, when typically we assume the famous person gets more credit than he or she deserves. My conjecture is that there is a combination of factors that led to this anomalous situation. First, there is the fact that from the beginning of quantum theory, with Max Planck in 1900, to its maturation with Werner Heisenberg, Schrödinger, and Paul Dirac, a full quarter century had passed: Very few of the key players in the final stages appreciated Einstein’s absolutely seminal role between 1905 and 1911, when he was the only person to truly understand the crisis in classical physics.

Second, and closely related, was his own uncompromising rejection of the theory in 1926, so that over time even he downplayed his own role. In fact, his autobiographical sketch, written late in life, omits major, Nobel-caliber contributions he made to quantum theory, such as predicting Einstein–Bose condensation. Third, Einstein, Schrödinger, and De Broglie had very few students and no “school” that followed them, in contrast to Niels Bohr, Max Born, and Heisenberg. Hence the next generation was not educated in the history of the development of quantum mechanics in a full and balanced manner, despite the good will that these three held toward Einstein.

PT: What were the most and least challenging aspects of penning a history and a biography?

Stone: There were at least two major challenges that come to mind. I would have liked to learn German for the project and read the relevant sources in the original. This would also have given me access to the archived but not translated letters between Einstein and colleagues, written during the period 1922–27. The Einstein papers project has translated and published all relevant materials up until 1922.

The second challenge was to balance my desire to write a readable, narrative-driven book with my wish to add to the scholarly canon on Einstein’s science by documenting adequately my interpretations of the historical events. My main method was to use actual quotations from Einstein and the other main characters whenever possible to support my telling of the story.

PT: Do you set the record straight on the “God doesn’t play dice” quote?

Stone: I would say I put it in perspective. Yes, he did say this in 1926, in his initial definitive rejection of quantum mechanics based on the Born interpretation, and he was troubled by the loss of strict causality this view implied. But I document that he himself added the feature of intrinsic randomness to the structure of quantum mechanics in 1916–17 with his concept of spontaneous emission of radiation. And, as Born said many times, Einstein proposed essentially the Born interpretation himself in 1918 to interpret the wave–particle duality of light.

So Einstein understood this approach perfectly and was rejecting it not on scientific but on philosophical grounds. In addition, later in life he moved away from focusing on the breakdown of causality in quantum mechanics and objected more to the apparent role of the observer: “Do you really think the moon isn’t there when you are not looking at it?” Finally, just to be clear, Einstein never believed in an anthropomorphic and moralistic god; he used the term for God, the “Old One,” as a metaphor for nature, which he felt could not be described in quantum theory.

PT: What’s the connection between Einstein the Valiant Swabian and the physicist who played a major role in the development of quantum theory?

Stone: The Valiant Swabian was a delightful nickname that Einstein, who was born in the southern German region of Swabia, used for himself with his first wife, Mileva Marić, before 1905. It refers to a brave and crafty crusader knight whose exploits were immortalized in a romantic poem. For me, it exemplified Einstein’s whimsical nature and captured a period in his life in which he was truly no different from a struggling artist, living hand to mouth, while fighting for recognition. At that time he was a feistier, more arrogant character than the saintly savant we came to know in his later years.

PT: What books are you currently reading?

Stone: A book I read recently that I really admired was Americanah (Knopf, 2013), by Chimamanda Ngozi Adichie. It is a great, sprawling, sociological novel confronting one of the central movements of our time: the pressure for immigration from the developing world to the developed world. I have just started reading Brave Genius (Crown, 2013) by Sean B. Carroll, which looks like a very exciting interweaving of biography—Albert Camus and Jacques Monod— art, and science. Finally, I am reading the excellent introductory text Fundamentals of Physics: Mechanics, Relativity, and Thermodynamics (Yale University Press, 2014), by my colleague R. Shankar, which is sort of a more accessible [21st-century] version of the Feynman Lectures.