Modeling observers as physical systems representing the world from within: Quantum theory as a physical and self-referential theory of inference (1705.04307v5)

Abstract: In 1929 Szilard pointed out that the physics of the observer may play a role in the analysis of experiments. The same year, Bohr pointed out that complementarity appears to arise naturally in psychology where both the objects of perception and the perceiving subject belong to 'our mental content'. Here we argue that the formalism of quantum theory can be derived from two related intuitive principles: (i) inference is a physical process performed by physical systems, observers, which are part of the experimental setup---this implies non-commutativity and imaginary-time quantum mechanics; (ii) experiments must be described from a first-person perspective---this leads to self-reference, complementarity, and real-time quantum dynamics. This approach sheds new light on the foundations of quantum theory and suggests fundamental equations in physics are typically of second order due to the physical nature of the observer. It also suggests some experimental conjectures: (i) the quantum of action could be understood as the result of the additional energy required to transition from unconscious to conscious perception; (ii) humans can observe a single photon of visible light; (iii) self-aware systems and the neural correlates of the self should be composed of two complementary sub-systems, much like the DNA molecule is composed of two strands---this may help explain the double-hemisphere architecture of the brain. Moreover, this approach may help bridge the gap between science and human experience. We discuss the potential implications of these ideas for the modern research programs on consciousness and contemplative science. As side results: (i) we show that message-passing algorithms and stochastic processes can be written in a quantum-like manner; (ii) we provide evidence that non-stoquasticity, a quantum computational resource, may be related to non-equilibrium phenomena.