Angular momentum in astrophysical discs and its impact on galaxy evolution

In this thesis, I develop models for how galaxies form and evolve. I focus on galaxies that have disc-like structure, outlining the fundamental importance of angular momentum in their formation and evolution. My model provides the most detailed accounting of this to date. I compare and contrast this and other models to state-ofthe- art supercomputer simulations of the entire growth of structure and galaxies throughout the Universe. I also use General Relativity to model how black holes can grow by accreting gas. This thesis contributes to mankind’s efforts to understand how the Universe came to be the way we observe.