AP 2 - Relativity and Quantum Optics

Don't these two guys look relaxed?  They were long-time friends, who both won Nobel Prizes for contributions to what we call still Modern Physics, even though it is more than 100 years old.  Niels Bohr is on the left, and the face,  hair, and mustache of the guy on the right are one of the 20th century's iconic images, so you probably know who he is.