Leon Max Lederman (1922–2018)

![Figure][1] PHOTO: WIKIMEDIA COMMONS Leon Max Lederman passed away quietly on 3 October in Rexburg, Idaho. He was 96 years old. A pioneer in particle physics, Leon shared the 1988 Nobel Prize in Physics. He was an influential public champion for science and science education, a transformational scientific leader, and a role model to generations of scientists young and old. Leon was born to Russian-Jewish immigrants in New York City on 15 July 1922. Although neither parent had finished school, they instilled in their son a love of learning that he carried with him all his life. Leon's education started at P.S. 92 on Broadway and 95th and ended just a few blocks north of that at Columbia University, where he received a Ph.D. in physics in 1951. In between, he attended New York public schools and earned his undergraduate chemistry degree from the City College of New York in 1943. Columbia University remained his academic home until he left to assume the directorship of Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, in 1979. Leon often spoke with a combination of pride and humor about his early days at Columbia University. In 1956, Leon and collaborators used Brookhaven's Cosmotron to show the existence of the long-lived neutral kaon, the KL, distinct from the short-lived neutral kaon, the KS. This experiment established the weak eigenstates of the neutral kaon that were proposed by physicists Murray Gell-Mann and Abraham Pais in 1955. The next year, Leon's group used the Nevis accelerator to discover nonconservation of parity in muon decay. Remarkably, they conceived of the idea during the half-hour drive from the main campus to Nevis one Friday, constructed the experiment that evening, and collected the data by the end of the weekend, demonstrating clear evidence for the fundamental result. In 1962, Leon and his colleagues led a team that established the existence of a second-generation neutrino, the muon neutrino. He would share the Nobel Prize in recognition of this work. In addition to the importance of the two-neutrino result in the development of the standard model of particle physics, the experiment pioneered the use of neutrino beams to study weak interactions. In the 1970s, Leon's interests turned to particles produced at high transverse momentum in high-energy proton-proton collisions. A sequence of ever-higher-energy experiments at Brookhaven, the Intersecting Storage Ring at CERN, and finally at Fermilab culminated in the 1977 discovery of the bottom quark, one of six known quarks. Shortly afterward, Leon became the second director of Fermilab. During his three decades as an experimental particle physicist, he supervised 50 Columbia University Ph.D. candidates and was a mentor to many other young students and postdocs. Influenced by his mentor, physicist and 1944 Nobel Prize winner Isidor Isaac Rabi, Leon thought big. His 1963 paper, “A truly national laboratory,” envisioned a new model for a national accelerator laboratory; the vision was realized in the 1967 founding of the National Accelerator Laboratory (renamed Fermilab). He was also a major proponent and spokesperson for the ill-fated Superconducting Super Collider, a planned 87-km-circumference accelerator that was approved in 1989 and canceled in 1993. He was a founding member of the High-Energy Physics Advisory Panel (to the U.S. Atomic Energy Commission and later to the U.S. Department of Energy) and the International Committee on Future Accelerators. As director of Fermilab from 1979 to 1989, Leon oversaw the construction of the Tevatron complex, the first superconducting accelerator and the world's most powerful accelerator from 1983 until it was eclipsed by CERN's Large Hadron Collider in 2009. Imagining unification of the inner space of particle physics with the outer space of cosmology, in 1983, Leon started the first astrophysics group at an accelerator laboratory. In addition to scientific leadership, with characteristic charm and humor, Leon transformed Fermilab from a frontier outpost in the cornfields of Illinois into a cosmopolitan center for science and science education. As a professor at Columbia University, Leon reached many generations of undergraduates in his “physics for poets” class. He transposed his love of teaching to Fermilab, where he instigated Saturday Morning Physics, a weekend class for area high-school students featuring lectures by Leon and other Fermilab scientists. He also started a public education and outreach effort at Fermilab directed toward precollege students. Beyond Fermilab, Leon was a founder of a residential state-sponsored high school for science and mathematics and a Chicago-based teacher academy for math and science. His leadership in education and outreach inspired physicists to communicate with the public. The author of several books for the general public, including The God Particle , Leon wrote with the same humor, wit, and charm that drew people to his public lectures. He had no equal in communicating the joys of physics. One of the great experiences of Fermilab in the 1980s was dining with the Ledermans in their Fermilab farmhouse. Some guests would be from Fermilab and others would be U.S. senators, cabinet members, Department of Energy officials, writers, artists, and poets. After a wonderful dinner prepared by Leon's wife, Ellen, we would retire to the living room, where there always seemed to be a large fire, even in summer. Over cigars and (a lot of) cognac, Leon would regale us with tales of his life in (and out of ) physics with humor and wit. He made his discoveries sound easy, but we knew they were built on years of experience. After stepping down as director of Fermilab, Leon was a professor of physics at the University of Chicago and later at the Illinois Institute for Technology in Chicago. In 2012, Leon retired to rural Idaho. The boy from the Bronx transitioned to hiking, skiing, riding horses, and relaxation. Although removed from his previous life, he remained close to his many friends and admirers. Leon was a great physicist, a visionary leader, a generous mentor, and a charismatic inspiration. The world seems a smaller place without him. [1]: pending:yes