This chapter was written in the hope that it might serve a readership that may not necessarily be familiar with the details of Einstein's general relativity theory but that nevertheless may appreciate the gist of Gödel's contribution to relativistic cosmology. I have included all the technical details that general readers may wish to skip but that those familiar with relativity theory might wish to review. In particular, I give an elementary derivation of Gödel's metric and of its geodesics.

Gödel's brilliant burst into the world of physics in 1949 came as a surprise to those who knew him “only” as one of the greatest logicians of all time and thus as a very pure mathematician. However, to his colleagues at the Institute for Advanced Study (AIS) in Princeton, it was less surprising. At IAS, he had famously befriended Einstein, and much earlier, before switching over to mathematics, he had even entered the University of Vienna (in 1924) as a physics student and attended lectures by Hans Thirring, one of the earliest protagonists of Einstein's theories. Moreover, although this was not apparent from his published work, Gödel had maintained a lifelong interest in physics, attending the physics seminars at IAS and keeping abreast of ongoing developments. Then came the crucial trigger: the year 1949 brought Einstein's seventieth birthday, and Gödel was expected to contribute to the planned Festschrift for his friend. Not for the first time did pressure prove conducive to invention.