Morrison, a professor emeritus at the Massachusetts Institute of Technology, died in his sleep at his home Friday, the university announced Monday.
"Phil was a great physicist," said Marc Kastner, chairman of the physics department at MIT. "He was spectacular at explaining physics to the public, too."
Morrison was the host of "The Ring of Truth," a six-part series aired by PBS, and a book review editor for the magazine Scientific American.
Morrison was a group leader during the Manhattan Project, which launched the age of nuclear weapons, and was present for the detonation of the first atomic bomb on July 14, 1945 in New Mexico.
"We knew we had done something remarkable and terrifying," he later said of that day.
Morrison also helped assemble the bomb that was dropped on Nagasaki, Japan, and was part of a scientific team sent to assess bomb damage after Japan's surrender ended World War II.
The damage that he saw from conventional and atomic bombs convinced him of the need for arms control.
Morrison's views on disarmament led to accusations that he was a communist sympathizer, and he was called to testify before the U.S. Senate Internal Security Subcommittee in 1953.
During the 1950s, Morrison began to concentrate on theoretical astrophysics. In 1959 he and Guiseppe Cocconi proposed a "discriminating search" for radio signals emanating from extraterrestrial beings.
Morrison was born in Somerville, New Jersey, on Nov. 7, 1915. He was stricken with polio, a development that led him to start tinkering with machinery. He was building radios by age 5.
He is survived by a stepson, Bert Singer, of Cambridge.