J. Robert Oppenheimer was the answer to Enigma Day #19 in the People category. J. Robert Oppenheimer is a American Physics figure active in the field of Science, no longer with us. To find J. Robert Oppenheimer, hot guessers typically started with the era (1900-1950), then narrowed by nationality and field. Figures from the same era and field would have scored 70%+ against this answer.