I decided to jump ahead one post because this worked out better than I expected. The attached notebook mentions conquering a dragon named Ansatz Schwarzschild, which really means deriving the Schwarzschild metric ab-initio in the UD calculus. I was going to post that notebook first, before this one, but it's kind of dry: necessary physics and UD, but not necessarily entertaining. In the attached notebook, we conquer the much-more-fearsome dragon named Ansatz Kerr, with a magical sword named Ernst. The result is a beautiful Manipulate for exploring orbits around a spinning black hole. I promise to post about Ansatz Schwarzschild soon, but with that apology out of the way, here is the tale of the quest to conquer Ansatz Kerr.