Max Delbrück

Max Delbrück trained in theoretical physics with Niels Bohr, then turned to the question of how genes copy themselves, choosing viruses that infect bacteria as the simplest system. With Salvador Luria he designed the 1943 fluctuation test showing that bacterial mutations arise at random, and the informal phage group he led trained a generation of molecular biologists. He shared the 1969 Nobel prize with Luria and Alfred Hershey.