The most intelligent picture ever taken: Participants of the 5th Solvay Conference on Quantum Mechanics, 1927. They are, among others: Albert Einstein, Marie S. Curie (the only woman in the conference), and Niels Bohr. 17 of the 29 attendees were or became Nobel Prize winners. 
The International Solvay Institutes for Physics and Chemistry, located in Brussels, were founded by the Belgian industrialist Ernest Solvay in 1912, following the historic invitation-only 1911 Conseil Solvay, considered a turning point in the world of physics.
1) From back to front and from left to right *deep breath*: Auguste Piccard, Émile Henriot, Paul Ehrenfest, Édouard Herzen, Théophile de Donder, Erwin Schrödinger, Jules-Émile Verschaffelt, Wolfgang Pauli, Werner Heisenberg, Ralph Howard Fowler, Léon Brillouin
2) Peter Debye, Martin Knudsen, William Lawrence Bragg, Hendrik Anthony Kramers, Paul Dirac, Arthur Compton, Louis de Broglie, Max Born, Niels Bohr, Irving Langmuir, Max Planck, Marie Skłodowska Curie, Hendrik Lorentz
3) Albert Einstein, Paul Langevin, Charles Eugène Guye, Charles Thomson Rees Wilson, Owen Willans Richardson.
This conference was also the culmination of the struggle between Einstein and the scientific realists, who wanted strict rules of scientific method as laid out by Charles Peirce and Karl Popper...
... versus Bohr and the instrumentalists, who wanted looser rules based on outcomes. Starting at this point, the instrumentalists won, instrumentalism having been seen as the norm ever since...
... although the debate has been actively continued by the likes of Alan Musgrave.
Who would you add to this photo?
Photograph of the first conference in 1911 at the Hotel Metropole.
At this point, Marie Curie - alone among them, had won Nobel Prizes in two separate scientific disciplines.
