RARE publication of papers and discussions that took place at the Fifth Solvay International Conference on Electrons and Photons in October 1927, where the world`s most notable physicists met to discuss the newly formulated quantum theory. The leading figures were Albert Einstein and Niels Bohr. 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. 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; the instrumentalists won, instrumentalism having been seen as the norm ever since. Contains H.A.Lorentz`s portrait as frontispiece. [CONTENTS]: H.-A.Lorentz - Notice nécrologique; Cinquieme Conseil de Physique / W.-L.Bragg - L`intensit de reflexion des rayons X / Arthur H.Compton - Discordances entre l`experience et la theorie electro-magnetique du rayonnement / de Broglie - La nouvelle dynamique des quanta / Max Born et Werner Heisenberg - La mecanique des quanta / Erwin Schrödinger - La mecanique des ondes / Niels Bohr - Le postulat des quanta et le nouveau development de l`automatisme. 255x165mm. VIII+289 pages [+7]. Softcover. Cover detached, yellowing, wrinkled and tattered. Front cover right bottom and left upper corners, rear cover bottom edges and right upper corner, and spine partly missing. Small sticker on rear cover left bottom corner. Spine worn and stained. Binding slightly loose. Several last pages coming loose from binding. Pages upper corner wrinkled. Pages yellowing. [SUMMARY]: This rare book, one of the most significant historical documents of modern science, is otherwise in good condition.