The first act takes place about a month before the bomb is to be tested, and the second act is set in the early morning of July 16, 1945 (the day of the test). During the second act, time frequently slows down for the characters and then snaps back into reality. The opera ends in the final, prolonged moment before the bomb is detonated. Although the original commission for the opera suggested that U.S. physicist J. Robert Oppenheimer, the "father of the atomic bomb," be fashioned as a 20th-century Doctor Faustus, Adams and Sellars deliberately attempted to avoid this characterization. Alice Goodman worked for two years with Adams on the project before leaving, objecting to the characterization of Edward Teller, as dictated by the original commission.