atomic age

The atomic age is the period of human history beginning with the development and use of nuclear weapons and nuclear power, generally dated from 1945 when atomic bombs were dropped on Japan.

The term evokes both the promise of nuclear energy and the threat of nuclear annihilation that shaped Cold War culture: Growing up in the atomic age, we practiced duck-and-cover drills. (Capitalized Atomic Age is the same period treated as a proper historical era.)