Physicist and university administrator Robert Ambrose Thornton was born in Houston, Texas, on May 6, 1902 to Frank Thornton, a laborer, and the former Mary Jane Sullivan, a midwife. Thornton attended Houston Colored High School but later graduated from Los Angeles Polytechnic High School in California. He entered Howard University in 1918 to study physics and mathematics. During his time in Washington, D.C. he worked as a student teacher and, hoping to break into show business, auditioned to sing in the hit Broadway musical comedy Shuffle Along. During this period, he became an associate of concert-tenor Roland Hayes and composer Harry T. Burleigh. In 1921, he first met Albert Einstein who gave a lecture in Washington’s Belasco Theater.
Thornton pursued graduate study at Ohio State University where he earned a master’s degree. He then studied for his doctorate at Harvard University, Yale University, and the University of Chicago where he was a Rockefeller fellow. In 1924, he married home economics professor Jessie Lea Bullock at Shaw University, the first of three historically black colleges and universities (HBCUs) where he taught mathematics and physics for the next two decades. During this period he also taught at Johnson C. Smith University, and Talladega College.
In 1944, he left Talladega to launch a liberal arts program at the University of Puerto Rico. While there Thornton wrote to Einstein requesting his assistance in establishing a philosophical basis for the program. Einstein responded, beginning a nine-year correspondence which lasted until 1953. Thornton and Einstein also had seven face-to-face meetings mostly at Princeton University in New Jersey where Einstein taught.
In 1947 Thornton, at the age of 45, was awarded his doctorate in physics at the University of Minnesota and began teaching as an associate professor at the University of Chicago. He next taught at Brandeis University (1950-1953); worked as a dean at Dillard University (1953-1955), and later at Fisk University (1955-1956). Beginning in 1956 he taught physics at San Francisco State College and in 1963, he was appointed its first Dean of the School of Natural Sciences, a position he held until 1967.
Thornton returned to the classroom, teaching at the University of San Francisco from 1967 to 1977. In 1979, the university awarded him an honorary doctorate of science; and at a ceremony in 1981 at San Francisco State University his 11 years of service there was honored when the new science and engineering building was christened the Robert A. Thornton Hall. His final employment was as visiting professor at the University of the District of Columba from 1980 to 1982. Thornton died in Fairfax, Virginia on March 7, 1982 at the age of 79. Just prior to his death, Thornton had been editing transcripts of his years of conversations with and letters to Albert Einstein.