existential-risk

The Milky Way holds 200 to 400 billion stars and we have found no sign of another civilization. The Great Filter proposes that one step on the road from chemistry to spacefaring is almost impossible, and we do not know whether we have already passed it.

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.