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 planet
• His case, built on isolated ecosystems like Australia and Madagascar, that hu ...