One of my all time favorite pictures, this comes from what may have been the most valuable academic conference in history, the Fifth Solvay International Conference on Electrons and Photons held in Brussels, Belgium 1927. Rarely has a single conference involved such critical debate about a new theory (I'm no physicist, of course).
From Wikipedia's page: "Perhaps the most famous conference was the October 1927 Fifth Solvay International Conference on Electrons and Photons, where the world's most notable physicists met to discuss the newly formulated quantum theory. The leading figures were Albert Einstein and Niels Bohr. Einstein, disenchanted with Heisenberg's "Uncertainty Principle," remarked "God does not play dice." Bohr replied, "Einstein, stop telling God what to do." (See Bohr-Einstein debates.) Seventeen of the twenty-nine attendees were or became Nobel Prize winners, including Marie Curie, who alone among them, had won Nobel Prizes in two separate scientific disciplines."
The picture includes (by row):
A. Piccard, E. Henriot, P. Ehrenfest, Ed. Herzen, Th. De Donder, E. Schrödinger, J.E. Verschaffelt, W. Pauli, W. Heisenberg, R.H. Fowler, L. Brillouin;
P. Debye, M. Knudsen, W.L. Bragg, H.A. Kramers, P.A.M. Dirac, A.H. Compton, L. de Broglie, M. Born, N. Bohr;
I. Langmuir, M. Planck, M. Curie, H.A. Lorentz, A. Einstein, P. Langevin, Ch. E. Guye, C.T.R. Wilson, O.W. Richardson