Near Zero

Teller raises the possibility that an atomic detonation could trigger a chain reaction in the atmosphere. Calculations put the chance near zero, and the Trinity test proceeds despite the irreversible stakes.

Tiny and uncertain probabilities deserve exceptional scrutiny when the downside is civilizational and there is no rollback. Wartime competition also compresses the time and independence available for safety judgment.

Historically, atmospheric ignition was studied and judged physically negligible; the film compresses the uncertainty for drama.