Fundamental sources of unpredictability
Murray Gell‐Mann · Complexity · 1997
Of course, spontaneous symmetry breaking may give rise to some parameters and even to a choice of solutions, with probabilities for the various alternatives. I shall deal with that possibility further on.) This second assumption is equivalent to stating that there is no necessary fundamental unpredictability stemming from ignorance of the universal dynamical law. 3) The density matrix (in the Schrsdinger picture) of the universe near the beginning of its expansion is also knowable. It must in any case be comparatively simple and very far from equilibrium. The second law of thermodynamics and the other associated arrows of time are explained by these properties of the initial density matrix along with the fact that the universe is still very young -- the interval of ten billion years is extremely short compared with the relaxation time from the special initial condition. Hartle and Hawking have proposed an ingenious pure state candidate for the density matrix, such that the wave fu