Ritter gives a lecture on the developments on the unification project of gravity with the other fundamental forces, focussing on two leading figures (or institutes): Veblen in Princeton and Cartan in Paris. They both worked on a geometrical theory of gravity, on the boundary between physics and mathematics. This lecture considers the interactions of these mathematicians with Einstein and others, and highlights the differences between their approaches.
This lecture is accompanied by a presentation. Prior knowledge of geometry and the unification of field theories is needed to fully grasp the message of this lecture.