Carl David Anderson, 85; Nobel Physicist at Caltech

Nobel Prize-winning physicist Carl David Anderson, whose discovery of the subatomic particle known as the positron proved the existence of antimatter, died Friday at his San Marino home after a short illness. He was 85.

Anderson, who entered Caltech in Pasadena as an 18-year-old freshman and never left, was a key figure in an age in which such theorists as Albert Einstein and Enrico Fermi and experimentalists such as himself probed the workings of the atom.

Only a thin set of long-ago circumstances prevented his name from becoming a household word.

Six years after winning the 1936 Nobel Prize at the age of 31, Anderson was approached about heading a top-secret government project then based at the University of Chicago. A personal situation prompted Anderson to decline, and the physicist who was to be his assistant, J. Robert Oppenheimer, ultimately became known as the principal creator of the atomic bomb.

In a 1990 interview in his San Marino home, Anderson expressed no regrets about his decision, noting the burden it had placed on his friend “Oppie.” He reached toward an end table and showed a copy of the McCarthy-era congressional hearings into Oppenheimer’s loyalty to the United States.

“Who would want this?” he asked.

In the interview, Anderson spoke wistfully of his decades at Caltech, first as student under such figures as Oppenheimer and Caltech major-domo Robert A. Millikan, and later as their colleague.

Anderson was a graduate student specializing in X-ray research when, Millikan--himself a Nobel laureate--suggested that he “was getting too provincial” and would benefit from studying at another major physics research center. A few months later, however, Millikan urged him to stay one more year to work on cosmic ray experiments.

Anderson assembled a device called a “magnet cloud chamber,” partly by borrowing equipment from a Southern California Edison salvage yard. Anderson was 27 when his photographic studies of cosmic rays revealed strange positively charged patterns that he concluded could only be caused by electrons. Until then, physicists believed that all electrons had a negative charge.

His hypothesis, Anderson recalled, “met a wall of resistance.” The notion of Anderson’s “positron” suggested that the complexities of elementary-particle physics were far greater that most physicists had imagined.

Within a few years, however, two other physicists independently confirmed Anderson’s findings. The Nobel Prize soon followed, Anderson sharing the prize with Viktor F. Hess, who had discovered cosmic rays two decades earlier.

Anderson, an untenured assistant professor, was teaching a physics class when Millikan delivered the news of the Nobel.

“I thanked him and went back to teaching the class,” recalled Anderson. He didn’t even mention the prize to his students. “We talked about physics, I guess . . . I was stunned.”

Anderson, who was caring for his ailing mother, had to borrow $500 from Millikan for the trip to Stockholm. His share of the Nobel was $20,000. He put half the money toward his mother’s medical care, and half he invested in Arcadia cabbage patches, correctly anticipating the suburban development to come.

By the time he won the Nobel, Anderson and a collaborator, Seth Neddermeyer, discovered another new particle, now known as “meson.” Although Anderson was best known for the positron, he was actually prouder of the meson, he said. He just stumbled upon the positron, he said, but the meson--any of several unstable particles first observed in cosmic rays--represented four years of detecting clues and resolving paradoxes.

Anderson once recalled how he and Neddermeyer used to work until midnight, then go for a long walk through Pasadena discussing their project. They also took their machine to the top of Pike’s Peak and, in later years, aloft in a Navy B-29 to study cosmic rays. “It was a lot of fun,” Anderson said.

In early 1942, Anderson was still caring for his ailing mother when a fellow Nobel laureate, Arthur Compton of the University of Chicago, recruited him for the fledgling Manhattan Project with the suggestion that Oppenheimer would be his assistant.

An Oppenheimer biographer once wrote that Anderson declined the post because it didn’t seem prestigious. Nonsense, Anderson said.

The most critical obstacle, Anderson said, was an anti-profiteering law that prohibited pay increases of more than 20% for people engaged in the war industry. He was reluctant to move his mother to Chicago and the pay would not have allowed him to relocate and provide care for her in the Los Angeles area.

Besides, he said, it was by no means clear the Manhattan Project would work.

As it turned out, Neddermeyer joined Oppenheimer in Los Alamos and played a crucial role in perfecting the bomb’s detonator. Anderson, meanwhile, worked in an artillery rocket project headed by another Caltech colleague, Charles Lauritsen. Caltech was virtually a defense contractor in those days, he said.

In later years, Anderson married and raised a family while assuming more of an administrative role at Caltech, serving as chairman of the division of physics, mathematics and astronomy. He saw several fellow Caltech physicists join the Nobel ranks, as well as a former student, Donald A. Glaser, who won for the invention of a research tool known as the “bubble chamber” while at the University of Michigan.

Born in New York and raised there and in California, Anderson was a graduate of Los Angeles Polytechnic High School. He was named to the National Academy of Sciences in 1936 and was the recipient of three honorary doctorates.

Anderson, named professor emeritus in 1976, was a Caltech booster to the end. What he liked best, he said, was a teaching load--only three classroom hours per week--that allowed long days for pure research.

He is survived by two sons, Marshall and David, and two grandchildren.

Funeral services will be private. Caltech will schedule a memorial service at a later date.