Carl David Anderson discovered two of the elementary particles of matter--the positron ("positive electron") and the meson, also known as muon (identical to the negatively charged electron in almost every aspect except mass). His discoveries dramatically expanded physicists' understanding of the nature and structure of the atom and confirmed theoretical predictions about the existence of such subatomic particles. Anderson's experimental identification of the positron earned him a Nobel Prize in 1936.

Anderson was born on September 3, 1905, in New York City, New York, the only son of Swedish immigrants from farming families. His mother was Emma Adolfina (Ajaxson) Anderson. His father, also named Carl David Anderson, came to the United States in 1896. When Anderson was a boy, the family moved to Los Angeles, where the father was just able to support the family by managing small restaurants. Anderson attended the Los Angeles Polytechnic High School. He had ambitions to be...