Pascual Jordan: Forgotten Quantum Pioneer

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Pascual Jordan: physics pioneer and Nazi – Image courtesy of GFHund

Should we reject the accomplishments of a scientist because of his vile politics?

Pascual Jordan was one of the great theoretical physicists of the 20th century, a principle founder of quantum mechanics, and inventor of quantum field theory.

Yet he never received the recognition given his famous colleagues. Why? Well, for one thing, he was a Nazi.

The Formative Years of Pascual Jordan

Pascual Jordan was born in 1902 in Hannover, Germany of mixed Spanish-German ancestry.

He was brought up in a conservative religious Protestant household. His father, an artist, insisted his son become an architect, but the headstrong Pascual studied physics and mathematics instead.

After attending Hanover Technical University, Jordan earned a PhD at the renowned Göttingen University in northern Germany. Recognized for his extraordinary mathematical skills, Jordan became assistant to mathematician Richard Courant and then to physicist Max Born.

The Roaring Twenties and the Birth of Quantum Mechanics

Early attempts by Neils Bohr to model the behavior of electrons in atoms had been only partially successful, and three physicists at Göttingen took up the challenge in 1925.

A young genius named Werner Heisenberg started it off with a seminal paper in July. Jordan and Born followed with a joint paper three months later (authored primarily by Jordan). In November, Heisenberg, Born, and Jordan joined to publish their now famous Dreimaennerarbeit — the first comprehensive theory of quantum mechanics.

Bohr’s Simplified Atomic Model. When an electron absorbs a photon, it jumps to a higher energy orbit (larger n). It then releases a photon and returns to a lower energy orbit. Image by Voyajer

That same year, Jordan gave Born a paper on modeling large numbers of electrons and other matter particles (half-integer spin particles). The absent-minded Born then went on a trip to M.I.T.  — he discovered Jordan’s paper in his suitcase six months later.

According to Born:

It contained what came to be known as the Fermi-Dirac statistics. In the meantime, it had been discovered by Enrico Fermi and, independently, by Paul Dirac. But Jordan was the first.”

Perhaps Jordan’s greatest contribution to science was the founding of quantum field theory (QFT) in 1926. Per ScienceWeek, the 24-year-old “was the first to realize that all things in the universe —  photons, electrons, protons, atoms, and elephants —  are field quanta.” According to QFT, our universe is made up of wave fields. The light and matter we detect are “ripples” in those fields. QFT has since become the most all-encompassing theory in the history of physics, describing all known phenomena in nature except gravity.

In 1927, Jordan went on to write two pioneering papers: the  creation and destruction of photons with Eugene Wigner, and a spacetime treatment of quantum mechanics with Wolfgang Pauli.

Jordan followed this up with a remarkable, but not generally known, dissertation on symmetry in the mid-1930’s. He also created a new form of mathematics called Jordan algebra, now used in projective geometry and number theory. His interests then drifted to quantum biology, psychology, and later to cosmology.

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