This book has a lot of math that I was cheerfully willing to ignore because I was listening to it and perfectly happy to trust that it was correct. 
If you are the kind of person who needs to understand the mathematics when they are explained to you…possibly read this book more slowly than I did. 
But still read it—Falk’s study of the science of the Middle Ages and specifically how he locates it simultaneously within John of Westwick’s life and in the sociocultural context of what knowledge production was like is fascinating. I’ve hung out with enough medievalists that this was less a debunking and more a deep dive into what was known and thought. 
And also it was absolutely fascinating to see medieval monks grappling with many of the same astronomical questions as the rabbis of late antiquity and the Middle Ages.