Why not consider a "brain drain" out of Deutschland after World War 2? I know their economy was worse following the Versailles treaty, but before, during and after that war, wasn't there a considerable exodus of thinkers?

A follow up question? I read once that Diesel around the time of WWI left Germany on a boat for the US and was never seen again. Some speculate that he was assassinated. Is there any merit to this?

Walter Isaacson's biography of Albert Einstein touches on this. The treaty of Versailles did have a very significant negative impact on the economy. However there was a very strong national identity and Germany had a large intellectual base. In fact Einstein returned to Germany and accepted German citizenship again (he renounced his German citizenship as a teenager) in this time period.

The big drain came not because of economic difficulties, but because Nazi's took power; when Hitler declared that all Jewish professors were barred from the University system, Germany lost almost 70% of their Theoretical Physicists. In fact when Max Planck personally appealed to Hitler to reconsider the decision Hitler responded that he didn't care if Germany was set back scientifically for years as long as they got the Jews out of the University system they would eventually recover with Aryan scientists.