I did a little looking into that photo, since I find gatherings of such brain trusts interesting...
From Wikipedia:
link:
Solvay Conference - Wikipedia, the free encyclopedia
The International Solvay Institutes for Physics and Chemistry, located in Brussels, were founded by the Belgian industrialist Ernest Solvay in 1912, following the historic invitation-only 1911 Conseil Solvay, considered a turning point in the world of physics. The Institutes coordinate conferences, workshops, seminars, and colloquia.[1]
Following the initial success of 1911, the Solvay Conferences (Conseils Solvay) have been devoted to outstanding preeminent open problems in both physics and chemistry. The usual schedule is every three years, but there have been larger gaps.
And a screen shot of that year's photo w/names & a description of the year's topic:
