A naive search of the web in 1999 turned up the first web page listed below with the claim about Gödel learning about rotating universes from Thirring at the University of Vienna when he entered as a student. I contacted the page's author, who interestingly enough had done some history of science work on Gödel to the extent of using Princeton's archives and developing a television special for Austrian television on the topic, but was no longer interested in academics—traffic engineering was now his focus. Fortunately he copied his email response [see the second link below] to a colleague there at his university who then sent me a very interesting email [the third link]:
I never got a response from my request to the last person to edit his email for a web page addition to these archival materials, and the first person's web page later disappeared. However, it seems clear that there must be interesting materials in the German language in Austria that could be pursued to make available to the English speaking world more details on this early part of Gödel's life where he acquired his interest in physics and general relativity, so I include these documents here in order not to lose this possible opportunity.
Robert Jantzen
September 2000
[Later a book was published with "Jimmy" as a coauthor:
Gödel: A Life of Logic, John L. Casti with Werner DePauli, Perseus
Publishing, Cambridge, MA, 2000.]
The Princeton Mathematics Community in the 1930s