Could there be an "event horizon" beyond which an essentially infinite variety of initial conditions could have resulted in the present state?
I’m sorry, I don’t even know what that means. If our present cosmological models are right there could only be one initial condition (exceptionally low entropy) at the beginning. An infinite number of initial conditions would mean infinitely high entropy. To the best of our knowledge starting a universe with infinite high entropy produces nothing. Can you clarify?
I think Hangdawg is just saying that the one initial condition becomes unknowable if you try to extrapolate beyond some point in time and any guess on what it was back then is just as good as any other.
Is that right, Hangdawg?
NOTE: for those of you watching at home, "initial condition", referred to in the singular is meant to stand in for "the complete set of initial conditions at the moment in question".