Our Lonely Speck

Extinction might be the rule in the universe, not the exception.Charley Lineweaver studied history and English before switching to physics — and ended up on the NASA team whose 1992 discovery of fluctuations in the cosmic microwave background, the oldest light in the universe, helped earn his PhD supervisor a Nobel Prize. He's now an astrobiologist and cosmologist at the Australian National University. With his student Aditya Chopra, he proposed the Gaian Bottleneck: the idea that most life goes extinct before it learns to regulate its own planet, and that this, not the difficulty of starting life, may explain why the universe looks so empty.We talk about:Why extinction, not emergence, might be the hard part of staying alive on a planetHis case, built on isolated ecosystems like Australia and Madagascar, that human-like intelligence may never have been an inevitable outcome of evolutionWhy he thinks maths is useless for talking to aliens, and what trying to communicate with dogs, dolphins and plants actually teaches usWhere he agrees, and where he sharply disagrees, with his hero Carl Sagan on humanity's place in the universe