Congres Solvay

 The 1927 Solvay Congress in Brussels was attended by most of the leading physicists of the time. 

Dirac is in the second row, on Einstein's right. 

The other delegates are (left to right): front row

 I Langmuir, M Planck, Madame Curie, H A Lorentz, A Einstein, P Langevin, Ch E Guye, CT R Wilson, 0 W Richardson;

 second row: P Debye, M Knudsen,.W L Bragg, H A Kramers, P A M Dirac, A H Compton, L V de Broglie, M Born, N Bohr; back row; A Piccard, E Henriot, P Ehrenfest, E D Herzen, T H de Donder, E Schrodinger, E Verschaffelt, W Pauli, W Heisenberg, R H Fowler, L Brillouin.