From 2 to 4 June 1947, a carefully selected group of distinguished physicists assembled at Shelter Island, a small and secluded spot near the eastern tip of Long Island, to discuss the outstanding problems of physics. This was the first serious meeting of physicists who had played leading roles in World War II and then returned to the pursuit of peaceful science. The Shelter Island Conference succeeded in its purpose: It set the direction for physics for the next 30 years.
The main subject of discussion was the experiment of Willis Lamb and Robert Retherford, who used the tools of microwave spectroscopy, developed during the war for military purposes, to measure the fine structure of the energy levels of the hydrogen atom. The results showed a clear deviation of the observed levels from the predictions of the Dirac theory of the hydrogen atom. Lamb and Retherford measured a quantity that...
