"The world has lost one of the major voices of social conscience in science," Charles Weiner, MIT professor emeritus of the history of science, said in a statement.

"For more than 50 years, since his involvement in the development of the first atomic bomb, Philip Morrison has been a leading participant in the efforts to control and eliminate nuclear weapons," Weiner said.

Born in 1915, Morrison was one of the physicists working on the Manhattan Project, under the direction of Robert Oppenheimer. And in 1945, Morrison transported the bomb's plutonium core from the laboratory in Los Alamos to New Mexico for its first test.

Morrison was also on the Pacific island of Tinian when two bombs were launched toward Japan from an air base there. He later saw the aftermath of the bombing of Hiroshima during a postwar visit.

After the war, Morrison took up the antiproliferation fight as a member (and chairman) of the Federation of American Scientists.

Over the next four decades, at MIT, he focused his research on radiology, cosmic rays, gamma rays, astrophysics and cosmology.