This is a question asking for references. I'm not sure if it's appropriate for StackExchange. If it's not, please tell me, thanks! :)
I'm reading about the Mostow's rigidity theorem, and the proof uses the following (maybe well-known) result:
The geodesic flow on a manifold with negative curvature is ergodic.
The lecture note that I'm reading does not provide a reference for that. I have some background in Riemannian geometry, but I know nothing about ergodic theory. I wanted to learn the exact meaning of this statement, and it would be even better if I could learn the proof. Can anyone give me some reference about this result? All kinds of resources are welcomed, but I would prefer to have approachable textbooks.
Thank you very much!