  What must that probability assumption look like and how may it be justified? These questions were asked, and partly explored, by N. Krylov. Attempts at rationalizing this initial probability assumption have ranged from Krylov's own suggestion that it is the result of a non-quantum “uncertainty” principle founded physically on the modes by which we prepare systems, to the suggestion that it is the result of an underlying stochastic nature of the world described as in the Ghirardi-Rimini-Weber approach to understanding measurement in quantum mechanics. The status and explanation of the initial probability assumption remains the central puzzle of non-equilibrium statistical mechanics.