Max Born

• 1. Introduction

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  Max Born shared the 1954 Nobel Prize in Physics for work he had completed nearly three decades earlier. The delay was not an oversight. It was a slow reckoning with just how much he had changed the way science thought about reality. Born spent his Nobel lecture arguing that certainty itself was a fiction. "Ideas such as absolute certitude, absolute exactness, final truth," he told his audience, "are figments of the imagination which should not be admissible in any field of science." For a man who had watched quantum mechanics dissolve the old picture of the atom, this was not modesty. It was a statement earned through decades of hard intellectual work.

  Born was born on the 11th of December 1882 in Breslau, a city that is now Wroclaw in Poland. He died on the 5th of January 1970, in a hospital in Gottingen. Between those two dates, he helped build the mathematical scaffolding of modern physics, trained an astonishing number of the 20th century's leading scientists, lost his professorship to the Nazis, and found a second life in Scotland. His story raises questions that run through the whole of 20th century physics. How do you measure the work that happens behind the scenes? What does it mean to interpret an equation rather than discover one? And how does a man who helped dismantle classical certainty come to believe that probability is not a weakness of knowledge but its very foundation?

• 2. Gottingen and the Mentors

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  Felix Klein had the power to make or break academic careers, and Born learned that early. When Born arrived at the University of Gottingen in April 1904, Klein ran seminars alongside Carl Runge and Ludwig Prandtl on the subject of elasticity. Born was not interested in applied mathematics, but Klein pressed him to submit a thesis on the stability of elastic wires and tapes. Born initially refused. Klein was greatly offended.

  To recover the relationship, Born arranged for Carl Runge to serve as his thesis advisor, since Klein refused to supervise him directly. Woldemar Voigt and Karl Schwarzschild became his other examiners. He even had an apparatus built to test his theoretical predictions experimentally. On the 13th of June 1906, the rector of the university announced that Born had won the Philosophy Faculty Prize. A month later, his oral examination earned him a Ph.D. in Mathematics with magna cum laude distinction.

  David Hilbert was a different story. From the first class Born attended, Hilbert identified him as having exceptional abilities. He was selected as lecture scribe, responsible for writing up class notes for the university's mathematics reading room. Hilbert then made him the first to hold an unpaid, semi-official position as assistant. That regular contact with Hilbert proved invaluable. His introduction to Hermann Minkowski came through his stepmother, Bertha, who had known Minkowski from dancing classes in Konigsberg; the connection led to Sunday dinner invitations at the Minkowski household. These three mathematicians would each leave a mark on Born's career, though Minkowski's influence was cut short by his sudden death from appendicitis on the 12th of January 1909.

• 3. Rigidity, Relativity, and a Flooded Lab

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  Albert Einstein published his paper on special relativity in 1905, and Born was immediately drawn in. He began researching the subject, only to discover that Minkowski was already working along the same lines. Rather than competing, Minkowski invited Born back to Gottingen to pursue his habilitation there. Otto Toeplitz helped Born brush up on matrix algebra so he could work with the four-dimensional Minkowski space matrices at the heart of the project.

  When Minkowski died in January 1909, Born stepped in to present their joint results at a meeting of the Gottingen Mathematics Society. Felix Klein and Max Abraham challenged him publicly, rejecting relativity outright, and Born was forced to terminate the lecture. David Hilbert and Carl Runge came to his defence. After persuading him to try again, they attended a second presentation, at which he was not interrupted. Woldemar Voigt then offered to sponsor his habilitation thesis. The work was published as Die Theorie des starren Elektrons in der Kinematik des Relativitatsprinzips, which introduced the concept of Born rigidity.

  Before Gottingen, though, Born had briefly tried his luck in Breslau under Otto Lummer and Ernst Pringsheim, hoping to complete his habilitation in physics there. A minor accident during a black body experiment, a ruptured cooling water hose that flooded the laboratory, led Lummer to tell Born that he would never become a physicist. That blunt verdict sent him back toward theoretical work, which turned out to be precisely the right direction.

• 4. Building the Quantum Workshop

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  On the 9th of July 1925, Werner Heisenberg handed Born a paper titled Uber quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen for review and publication. Heisenberg's approach avoided unobservable electron orbits by working with transition probabilities, which required two indexes corresponding to initial and final states. Born read the paper and recognised the formulation as one that could be transcribed into the language of matrices, a skill he had learned from Jakob Rosanes at Breslau University.

  Matrices were, at the time, considered the province of pure mathematics. Gustav Mie had used them in a paper on electrodynamics in 1912, and Born himself had used them in his lattice theory of crystals in 1921. Neither application, however, had required matrix algebra in the full sense. Born's assistant and former student Pascual Jordan joined the transcription effort immediately. Their paper was received for publication just 60 days after Heisenberg's original. A follow-on paper co-authored by all three was submitted before the year ended.

  The result was a striking equation: pq minus qp equals h divided by 2pi times i, multiplied by the identity matrix I, where p and q were matrices for momentum and location. The left-hand side was not zero because matrix multiplication is not commutative. Born later identified this non-commutativity as entirely his own contribution; he also established that all elements off the diagonal of the matrix were zero. Born regarded the paper with Jordan as containing "the most important principles of quantum mechanics including its extension to electrodynamics."

  Erwin Schrodinger's wave mechanics arrived soon after and appealed to many physicists by seeming to restore classical determinism. Born rejected that appeal. In July 1926, he published what became the standard interpretation of the probability density function for psi-star times psi in the Schrodinger equation. Where Schrodinger's formalism computed a wave, Born argued it computed a probability. That single interpretive step, stating that the square of the wave function gives the probability of finding a particle in a given location, was the contribution the Nobel Committee eventually singled out.

• 5. Einstein, the Dice, and a Long Wait

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  On the 4th of December 1926, Albert Einstein wrote to Born and delivered what became one of the most quoted lines in the history of science: "Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the 'old one'. I, at any rate, am convinced that He is not playing at dice." The remark is usually shortened to "God does not play dice," but the full letter makes clear that Einstein's quarrel was with the probabilistic core of Born's own interpretation.

  In 1928, Einstein nominated Heisenberg, Born, and Jordan together for the Nobel Prize in Physics. The 1932 Prize went to Heisenberg alone, for the creation of quantum mechanics. Schrodinger and Dirac split the 1933 Prize. Born and Jordan received nothing. On the 25th of November 1933, Heisenberg wrote to Born acknowledging a "bad conscience" that he alone had received the Prize "for work done in Gottingen in collaboration, you, Jordan and I." Heisenberg was careful to insist that Born and Jordan's contribution could not be diminished by "a wrong decision from the outside."

  The wait extended for more than two more decades. Franck and Fermi nominated Born in 1947 and 1948 for his work on crystal lattices. He was also nominated repeatedly for solid-state physics and quantum mechanics. In 1954, the Royal Swedish Academy of Sciences finally awarded him the Nobel Prize in Physics, citing "his fundamental research in quantum mechanics, especially for his statistical interpretation of the wavefunction." By then Born was living in retirement in Bad Pyrmont in West Germany, having left Edinburgh two years earlier at the compulsory retirement age of 70.

• 6. The Institute and Its Students

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  Arnold Sommerfeld at the University of Munich ran a comparable institute, and when Born returned to Gottingen in 1921 to direct the Institute of Theoretical Physics, the two men operated on similar principles: tight collaboration with experimental physicists to test and advance theoretical ideas. In 1922, while Sommerfeld was lecturing in the United States at the University of Wisconsin-Madison, he sent his student Werner Heisenberg to serve as Born's assistant. Heisenberg returned to Gottingen in 1923, completed his habilitation under Born in 1924, and became a Privatdozent there.

  The list of physicists who passed through Born's institute at Gottingen reads like a directory of 20th century physics. Those who earned their Ph.D. degrees under him included Max Delbruck, Siegfried Flugge, Friedrich Hund, Pascual Jordan, Maria Goeppert Mayer, Lothar Nordheim, Robert Oppenheimer, and Victor Weisskopf. His assistants included Enrico Fermi, Werner Heisenberg, Gerhard Herzberg, Friedrich Hund, Wolfgang Pauli, Leon Rosenfeld, Edward Teller, and Eugene Wigner. Walter Heitler became an assistant in 1928 and completed his habilitation under Born in 1929. Delbruck and Goeppert Mayer each went on to win Nobel Prizes.

  Born's approach to mentorship was notably calibrated. He was described as letting his superstars stretch past him, while to those less gifted, he patiently handed out respectable but doable assignments. In 1919, Elisabeth Bormann joined the Institute for Theoretical Physics as his assistant. Working with Born, she developed the first atomic beams and was the first to measure the free path of atoms in gases and the size of molecules. That record of mentorship extended into his personal circle as well: he arranged a separate chair of experimental physics at Gottingen specifically for his long-time friend James Franck when negotiating his own appointment with the education ministry.

• 7. Exile and Edinburgh

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  In January 1933, the Nazi Party came to power in Germany. In May of that year, Born was one of six Jewish professors at Gottingen suspended with pay. Franck had already resigned. In twelve years, Born and Franck had built Gottingen into one of the world's foremost centres for physics. That institution was dismantled in a matter of months.

  Born wrote to Maria Goeppert Mayer at Johns Hopkins University and to Rudi Ladenburg at Princeton University looking for positions. He accepted an offer from St John's College, Cambridge, where he wrote The Restless Universe, a popular science book, and Atomic Physics, a textbook that went through seven editions and became a standard text. His position at Cambridge was temporary, and his tenure at Gottingen was formally terminated in May 1935. In November 1935, the Born family had their German citizenship revoked, leaving them stateless. A few weeks later, Gottingen cancelled Born's doctorate.

  He spent time in Bangalore in 1935, working with mathematician B. S. Madhava Rao on Born's nonlinear electromagnetic field theory; Madhava Rao's doctoral thesis and eight published papers in the Proceedings of the Indian Academy of Sciences came directly from that collaboration. At the close of his residency on the 18th of March 1936, Born signed and dated a studio portrait taken by Cyril Studio in Bangalore as a personal gift to Madhava Rao. The portrait is now preserved in the Madhava Rao family archive.

  Charles Galton Darwin then asked Born to succeed him as Tait Professor of Natural Philosophy at the University of Edinburgh. Born accepted at once and assumed the chair in October 1936. He worked there with two German assistants, E. Walter Kellermann and Klaus Fuchs, and one Scottish assistant, Robert Schlapp, investigating the behaviour of electrons. He received his certificate of naturalisation as a British subject on the 31st of August 1939, one day before the Second World War broke out in Europe. He remained at Edinburgh until he reached the retirement age of 70 in 1952.

• 8. Legacy and Last Years

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  In 1955, Born became one of the signatories to the Russell-Einstein Manifesto. His Nobel lecture in December 1954 had already mapped out the philosophical stakes he saw in his own work. "The belief in a single truth and in being the possessor thereof," he told the audience, "is the root cause of all evil in the world." For Born, the statistical interpretation of the wavefunction was not merely a technical result. It was a statement about the limits of human knowledge itself.

  Born is buried in the Stadtfriedhof in Gottingen, in the same cemetery as Walther Nernst, Wilhelm Weber, Max von Laue, Otto Hahn, Max Planck, and David Hilbert. The Max Born Medal and Prize was created in 1972 by the German Physical Society and the Institute of Physics, and is awarded annually. In 1982, the University of Gottingen held a ceremony in the 100th birth year of both Born and James Franck, the two institute directors who had run the physics programme there from 1921 to 1933.

  His family connections reached into unexpected places. His daughter Irene married a Welshman named Brinley Newton-John, and their daughter Olivia Newton-John was Born's granddaughter. His grandson Max Born acted in Fellini's Satyricon. His granddaughter Georgina Born became a musician and academic. Among his great-grandchildren is racing car driver Emerson Newton-John. On the 11th of December 2017, Google marked the 135th anniversary of Born's birth with a doodle designed by Kati Szilagyi, a small acknowledgment of a man whose interpretation of a single equation still frames every modern physicist's understanding of what a wavefunction actually means.