Fifth conference participants, 1927. Institut International de Physique Solvay. Third row:A. Piccard, E. Henriot, P. Ehrenfest, Ed. Herzen, Th. De Donder, E. Schrodinger, J.E. Verschaffelt, W. Pauli, W. Heisenberg, R.H. Fowler, L. Brillouin, Second row:P. Debye, M. Knudsen, W.L. Bragg, ...