The second Chris Fields lecture of "Physics as Information Processing" course: https://www.youtube.com/live/WkWIqpxWRM4 Session 2: why use quantum physics to understand active inference? The answer is the discreteness of information and the necessarily limited resolution of all physical measurements. These naturally lead to a discrete-eigenvalue representation of interaction, i.e. to quantum theory. We will see how quantum theory generalizes the holographic principle, how holographic screens function as Markov blankets, and how all physical interactions between separable (non-entangled) systems can be viewed as communication. This answers the question “to what does the FEP apply?” with “everything measurable.” Course syllabus Discussions at AII Discord server