The theory of quantum mechanics supports the basis of modern technology, for everything from supercomputers and ultra-precise timekeeping to digital encryption. It describes the movement of photons, electrons, and other subatomic particles.

Understanding how subatomic particles function helps us understand physics on a much larger scale. Just after World War I, Max Born, a German scientist, cracked the code that would help future generations of scientists understand the laws of modern quantum physics. For this pioneering work, today’s Google Doodle celebrates the physicist on the 135th anniversary of his birth.

## Who was Max Born?

Born in 1882, he was a physicist and mathematician whose work was instrumental in the development of the field of of “lattice dynamics,” the study of the vibrations of the atoms in a crystal, and was the first to surmise the way a metal reacts with a halogen (such as chlorine) to form an ionic compound, now known as the “Born-Haber Cycle.”

Later in his career, working with Werner Heisenberg (who later gained fame for the uncertainty principle), Born formulated rules to use quantum mechanics to explain how electrons move around the nucleus of an atom. For his pioneering work in the “fundamental research in Quantum Mechanics, especially in the statistical interpretation of the wave function,” Born was awarded the 1954 Nobel Prize in physics.

## Born’s Rule

Born is best known for his development of the Born Rule, which uses probability to determine the location of wave particles in the quantum system.

Inspired by Einstein’s work on the photoelectric effect, Born formulated the rule in a 1926 paper that attempted to solve the Schrödinger equation, a mathematical formula for studying quantum mechanical systems, for the scattering problem.

The only solution, Born discovered, was to calculate the odds of finding the location using a simple matrix instead of performing a series of complex equations. If you have all the probabilities across a set of potential results, you can understand what a wave system is doing without taking specific measurements.

Born’s rule states that if you square the magnitude of a wave function at a certain point, you’ll get the probability of finding a particle at that location (And almost a century after Born’s Rule was discovered, physicists don’t know precisely *why* [PDF] it works. They just know that it does.)

For Max Born superfans, Google is asking readers to try to spot the wave function in today’s Doodle, created by artist Kati Szilagyi.

## Forced to flee

During the first world war, Born performed research duties as a sound specialist for the German army. After the war, he returned to his alma mater, the University of Göttingen, to chair the physics-theory department.

Göttingen developed an international reputation for physics theory under Born’s leadership, issuing doctorates to renowned mathematicians including Victor Weisskopf, Siegfried Flügge, Maria Goeppert-Mayer, and Robert Oppenheimer.

Born was suspended from Göttingen when the Nazi Party came to power in 1933 because of his Jewish heritage. He fled to the United Kingdom, where he joined St. John’s College in Cambridge, and then worked as a professor of natural philosophy at the University of Edinburgh.

He became a British citizen on Aug. 31, 1939, one day before World War II broke out. He stayed at Edinburgh for 20 years until 1952, when he retired to West Germany and continued his research until his death at age 87 in 1970.