## Friday, October 05, 2007 ... //

### Solvay Conference 1927: eighty years later

Brussels has been a good neutral place to meet for quite some time. The most famous Fifth Solvay Conference occurred in the second part of October 1927, right after some of the most dramatic advances in physics of all time took place.

The participants were not bad: Einstein, Bohr, Heisenberg, Dirac, Planck, Born, de Broglie, Curie, Pauli, Schrödinger, Lorentz, Kramers, Compton, Debye, Ehrenfest, Langevin, and a few others. It is likely that it won't ever be possible to gather that many people who are responsible for such significant breakthroughs.

Concerning quantum mechanics of particles such as electrons, there was a portion of physicists who knew very well what was going on - Bohr, Heisenberg, Dirac, Pauli, Born, Ehrenfest, Debye, and partly Kramers - while the majority of the attendants, despite their qualities, were confused.

De Broglie was there primarily because he had prepared the ground for wave mechanics of Schrödinger but Schrödinger himself didn't quite understand the probabilistic nature of quantum mechanics or the equivalence of his picture with Heisenberg's matrix mechanics proven by Dirac. Einstein's admiration for determinism is a well-known story.

Einstein, Planck, Lorentz, and Kramers were stronger in dynamics of photons. At that time, relativity was still waiting to be reconciled with quantum mechanics and Dirac became the main guy in this mission. Among the quantum founding fathers, I would say that Wolfgang Pauli had the most modern and the most penetrating approach. He unambiguously became a relativistic field theorist and he would almost certainly be a string theorist today: it is truly paradoxical that crackpots in 2007 abuse exactly his name and quotes against string theory.