Max Born

Max Born the German-British physicist (1882-1970) who gave quantum mechanics its statistical interpretation, recognising that the wave function yields probabilities rather than definite values. For this work he received the 1954 Nobel Prize in Physics, shared with Walther Bothe, and he also made important contributions to lattice dynamics and optics.

Early Life and Education

Max Born was born on 11 December 1882 in Breslau, in the German Empire, the son of an anatomist. He studied at several German universities before settling at Goettingen, where he took his doctorate in 1906 under the mathematician David Hilbert. He then spent time in Cambridge and Breslau before taking up academic posts in Berlin and Frankfurt.

After service in the First World War, during which he worked on artillery and on the theory of sound ranging, Born was appointed professor of theoretical physics at Goettingen in 1921. He built there one of the world's great centres of theoretical physics, a place where gifted young people came from many countries to learn the new quantum theory at its source. The atmosphere of the institute was informal and international, and Born's patience with his students became legendary. His own early research concerned the dynamics of crystal lattices and the theory of relativity, and when Heisenberg arrived in Goettingen in 1922, Born recognised his talent at once and made him his assistant, setting in motion one of the most fruitful collaborations in the history of physics.

The Statistical Interpretation of the Wave Function

In 1926 Erwin Schroedinger formulated a wave equation for the electron and hoped that the waves were real matter waves, but the interpretation was unclear. Born proposed instead that the square of the wave function gives the probability of finding the particle in a given place. The wave function therefore describes not what a particle is but the likelihood of finding it, and quantum mechanics is inherently statistical. This rule, now called the Born rule, is the bridge between the abstract mathematics of the theory and the outcomes of laboratory measurement.

This interpretation, which Born arrived at while analysing collisions between particles, became the standard view and earned him the 1954 Nobel Prize in Physics, although the award came nearly thirty years after the work. It marked a decisive break with the deterministic physics of Newton, and although Einstein and others resisted the loss of certainty, the probabilistic reading of the wave function has stood up to every experimental test. Born himself regarded the abandonment of strict causality as the most profound consequence of the new mechanics.

The Goettingen School and Collaborators

Born's institute was the setting for some of the most profound work of the twentieth century. He collaborated with Werner Heisenberg and Pascual Jordan on the matrix formulation of quantum mechanics, sometimes called the Born-Jordan-Heisenberg theory, and he guided Heisenberg toward his uncertainty principle. Among his doctoral students and assistants were J. Robert Oppenheimer, Maria Goeppert Mayer, Enrico Fermi and Edward Teller. The list of those who passed through Goettingen in the 1920s reads like a roll-call of the founders of modern physics.

His generous and informal style of supervision helped to bring out the best in his students, and his textbook on optics and his lectures on the mechanics of the atom shaped the education of a whole generation. The Goettingen school produced contributions to statistical mechanics, solid-state theory and quantum theory that remain foundational, and many of its members carried its methods and standards to universities around the world when they were forced into exile.

Lattice Dynamics and Optics

Born is also remembered for his long collaboration with Theodore von Karman on the dynamics of crystal lattices. Together they developed the theory of vibrations in solids, distinguishing acoustic and optical branches, and produced work that underlies the modern understanding of thermal properties, phonons and the interaction of light with crystals. His book on the subject was for decades the standard treatise.

His textbook Principles of Optics, written with Emil Wolf, became a definitive reference. Born's breadth, ranging from the abstract foundations of quantum theory to the practical behaviour of crystals and light, illustrates his conviction that the deepest ideas arise from the careful study of concrete physical problems. He also wrote on the theory of the solid state and on the statistical foundations of thermodynamics, and his lectures attracted students from across Europe and beyond. Beyond his research, he took seriously the duty of explaining science to a wider public, and his writings on the social function of physics and on the dangers of nationalistic science grew directly out of his own experience of exile and of the misuse of scientific talent in war.

Exile, Later Life and Legacy

Of Jewish descent, Born left Germany in 1933 when the Nazi law dismissed Jewish scholars from their posts. He found refuge in Britain, teaching at Cambridge and Edinburgh, and continued to write and lecture. He was elected a fellow of the Royal Society and later settled in Bad Pyrmont in West Germany, where he devoted himself to the interpretation of science and to the cause of peace.

In his final years Born reflected on the philosophical implications of quantum mechanics and on the social responsibility of scientists, urging a recognition of the unity of scientific knowledge. He received the Nobel Prize two years before his death in 1970, and his collected papers illuminate the birth of quantum mechanics as seen by one of its most humane and central participants.

See also

• Born rule
• Quantum mechanics
• Goettingen school
• Lattice dynamics