Schr?dinger Equations and Diffusion Theory addresses the question "What is the Schr?dinger equation?" in terms of diffusion processes, and shows that the Schr?dinger equation and diffusion equations in duality are equivalent. In turn, Schr?dinger's conjecture of 1931 is solved. The theory of diffusion processes for the Schr?dinger equation tell us that we must go further into the theory of systems of (infinitely) many interacting...