cold war

Andrei Sakharov designed the Soviet hydrogen bomb in 1953, then spent three decades fighting for human rights — enduring exile, hunger strikes, and KGB surveillance.

The space race was a Cold War battle for supremacy, fought with rockets instead of bombs. It ended with humanity's greatest adventure.

The bombs dropped on Hiroshima and Nagasaki fissioned less than a kilogram of material each. Modern warheads are larger, but not a thousand times larger. Here is the physics, the arms-control record, and the evidence for and against the explanations of why none has been used in war since.

Nuclear war is the most discussed existential risk and the least understood. The bombs are the easy part. What comes after — nuclear winter, famine, collapse — is far more dangerous. Here's what science actually predicts.