Molendijk, Bart / Anefo · CC0

George Wald spent his career working out how the eye actually sees, tracing the light-sensitive pigments in the retina and how they convert light into a nerve signal — research that earned him a share of the 1967 Nobel Prize in Physiology or Medicine alongside Haldan Keffer Hartline and Ragnar Granit. Outside the lab he was an outspoken activist, warning in a widely circulated 1970 address that civilization would collapse within a few decades without immediate action on the problems facing it, a bluntness that made him as well known for his politics as for his science.