Hi Jim. Very insightful, but I address that when I talk about macroscopic systems. You are right about the crux of the problem being “what is an observer”. What we can show for microscopic systems is not directly applicable to macroscopic ones. And you are right, a photon is not an observer. When I talk about a particle traveling through a magnetic field, I explain that if there is no observer, then more entanglement merely results. It is only the presence of an observer that “selects” a particular state from an entangled state. Making the leap to a macroscopic system requires understanding how a quantum system becomes a macroscopic system: it is due to our (as observers) lack of knowledge about the quantum state: our uncertainty grows — hence entropy grows.