The 1927 Solvay physics conference is often cited as being the key meeting in the foundation of quantum mechanics. It certainly produced one of the classic photos (reproduced here). Physicists and chemists recognize many of the names and faces in this photo — it’s a snapshot of our shared scientific history.
Beyond the most famous person sitting front-and-center, there’s Marie Curie, nuclear chemist extraordinaire, easily spotted as the only woman there (thankfully the gender balance is a little better today, though we’re nowhere close to parity yet); Max Planck, arguably the founder of quantum physics; and Hendrik Lorentz, who laid a lot of the groundwork for relativity. Then the great quantum physicists: Niels Bohr, Max Born, Erwin Schrödinger, Wolfgang Pauli, Werner Heisenberg, Paul Dirac, and a host of others less famous to non-scientists, but whose names are still well-known to physicists and chemists: de Broglie, Brillouin, Debye, Bragg, and so on. Nearly every person in this picture made at least one major contribution to our modern understanding of the physical universe.
I may be late to discover this, but it turns out there is actually some film footage of this conference, now posted on YouTube:
Obviously there’s no sound (it was 1927, after all), but it’s great to see these eminent scientists mugging for the camera (or in some cases pointedly ignoring it — I’m not sure there’s photographic evidence that Pauli ever smiled in his life). Some of these scientists were friends in everyday life; some were not, but they shared a collegiality that is a credit to the international nature of science. In a few years, many of those scientists would be dislocated by war and Nazi racism; many ended up in the United States (Einstein in particular) or England. A few (Heisenberg, most notably) stayed in Germany and worked for the fascist regime, a decision that is still being discussed by historians of science today.
Part of the value of this iconic photo — and the film — is to humanize the history of science. They may collectively have revolutionized our understanding of the natural world, but there they are goofing around, discussing earnestly, yes, but laughing and joking and being human.