I like Physics from Symmetry by Jakob Schwichtenberg as an explanation of how spin arises from a modern understanding of physics. The book was written while the

I like Physics from Symmetry by Jakob Schwichtenberg as an explanation of how spin arises from a modern understanding of physics. The book was written while the author was a Masters student, and so it is much closer to the way an undergrad physics student would explain it to another student. The author is willing to skip details in favor of more general understanding. The way the book will describe it is from the perspective of group theory. If you assume that the laws of nature in a relativistic flat spacetime do not change under rotations, translations (in both space and time), and boosts (transformation between frames of reference of constant velocity), then these transformations define a Lie group called the Poincaré group. Representation theory then says that the representations of the Poincare group are characterized by two numbers. These two numbers are identified as a nonnegative mass and a spin. One interpretation is that these representations are indeed what "particles" are in Quantum Field Theory. https://en.wikipedia.org/wiki/Wigner%27s_classification https://en.wikipedia.org/wiki/Wigner%27s_classification