How do we know the Earth is 4.55 billion years old? It turns out the man who found the answer also had to save us from an invisible poison. In the Season 1 finale, Dr. Jeff Zurek tells the story of Dr. Clair Patterson, the geochemist who fought the lead industry and won.

Tracing Patterson’s path from the Manhattan Project to the University of Chicago and Caltech, we explore how his quest to date the solar system using lead isotopes in meteorites led to a terrifying discovery: global lead contamination. This episode covers the physics of radioactive decay, the invention of the Clean Room, and the fierce battle between Patterson and lead-industry scientists like Dr. Robert Kehoe. It’s a story of how "basic research" triggered the greatest reduction in public  ...