Scientists and engineers like to describe processes or systems made of smaller pieces using diagrams: flow charts, Petri nets, electrical circuit diagrams, signal-flow graphs, chemical reaction networks, Feynman diagrams and the like.   Many of these diagrams fit into a common framework: the mathematics of symmetric monoidal categories.  When we embrace this realization, we start seeing connections between seemingly different subjects.  We also get better tools for understanding open systems: systems that interact with their environment.  This takes us beyond the old scientific paradigm that emphasizes closed systems.

Going down the categorical systems theory rabbit hole; very good exposition from Baez as per usual. I also finally know what a monoidal category is, so that’s pretty handy. I ought to read the paper this talk is based on at some point.

see: https://math.ucr.edu/home/baez/rosetta/

via: https://en.wikipedia.org/wiki/Monoidal_category