Paul Frees

Self - Narrator (voice)

Jon Else

Interviewer

J. Robert Oppenheimer

Self (archive footage)

Hans Bethe

Self

Frank Oppenheimer

Self

Haakon Chevalier

Self

Robert Serber

Self

Holm Bursom

Self

Stirling Colgate

Self

Freeman Dyson

Self

Susan Evans

Self

Francis Fergusson

Self

Leslie Groves

Self (archive footage)

Elizabeth Ingram

Self

Robert Krohn

Self

Jon Else