John Archibald Wheeler; 1911-2007

John Archibald Wheeler is probably the greatest American physicist you never heard of. But you've certainly heard one of his neologisms; Wheeler gave black holes their names.
Wheeler spanned generations in physics. He discussed the deepest issues with Albert Einstein and Neils Bohr, taught Richard Feynman, and paved the way for cosmologists like Stephen Hawking. His career recalls the long gone era when scientists could do original work across the now separated disciplines of physics.
Wheeler looked more like a typical American businessman that like the philosopher-scientist from central casting. But, as the New York Times recounts, he was unique among U.S. physicists in his taste for the strolling the furthest edges of scientific thought:

Recalling his student days, Dr. Feynman once said, “Some people think Wheeler’s gotten crazy in his later years, but he’s always been crazy.”

Among his crazy musings that have become accepted part of our understanding of the world is his concept of quantum foam, in which space-time itself breaks down into chaos at very small distances.
Wheeler worked on the Manhattan Project, which brought him to Wilmington to live while he worked with the DuPont Company in 1943, while crossing the country to Chicago, Illinois and Hanford, Washington. He continued to do physics for the Pentagon when many of his colleagues were divided over nuclear weapons, Robert Oppenheimer and Vietnam. Wheeler wasn't doctinaire about his government work; he just thought he owed it to his country, and managed to remain friends with his colleagues across the political spectrum.
Perhaps he was just too interested in, and interesting to, the entire scope of physics to want to wall himself off from any segment of the 20th century's scientific community.
Photo: Emilio Segre Visual Archives