I have a master in physics, but I share your surprise over this paragraph in the OP. I’m a bit unsure though how widely and quickly the probability mass dissip

I have a master in physics, but I share your surprise over this paragraph in the OP. I’m a bit unsure though how widely and quickly the probability mass dissipates over possible future states. E.g. the existence of quantum computers implies that at least in some physical systems the probability mass stays concentrated on a few possible future states. I wouldn’t expect that to hold for the universe as a whole though.