Physical Observers and Quantum Reconstructions

Abstract: There is a multitude of interpretations of quantum mechanics, but foundational principles are lacking. Relational quantum mechanics views the observer as a physical system, which allows for an unambiguous interpretation as all axioms are purely operational, describing how observers acquire information. The approach, however, is based on the premise that the observer retains only predictive information about the observed system. Here, we justify this premise using the following principle: Physically embedded observers choose information processing strategies that provide them with the option to approach physical limits to the greatest possible extent. Applied to a lower limit on energy dissipation, the principle leads directly to a compact predictive model, thus justifying this core premise of relational quantum mechanics.