I'm halfway through the sequel. The physics are a lot harder to follow. Prob a bit harder in general, but I also think it's because I only have a "youtube" understanding of these concepts while I had a real understanding of most of the stuff from the first book like 4d geometry.
My understanding of 4d might have spoiled a big reveal that's coming up though.
My understanding of 4d might have spoiled a big reveal that's coming up though.