(ILLUSTRATION BY SEAN MCCABE; COURTESY OF PRINCETON UNIVERSITY LIBRARY (young Everett); COURTESY OF EUGENE SHIKHOVTSEV AND KENNETH W. FORD (adult Everett); U.S. DEPARTMENT OF ENERGY/PHOTO RESEARCHERS, INC. (mushroom cloud); COURTESY OF THE AMERICAN INSTITUTE OF PHYSICS, NIELS BOHR LIBRARY AND ARCHIVES (handwriting))