Louis Rosen was born in New York City on 10 June 1918.
Rosen earned his undergraduate and Masters degree from the University of Alabama and his doctoral degree from Pennsylvania State University.
Rosen joined the Manhattan Project at Los Alamos in 1944 and held various positions from group leader to division leader and director of the Meson Physics Facility (LAMPF). Rosen worked on the technology of assembling materials with sufficient rapidity to surmount the problem of pre-detonation. He also investigated the attenuation of electromagnetic signals by high explosives.