From http://www.worldsciencefestival.com/programs/holographic_world/ http://www.worldsciencefestival.com/programs/holographic_wor... it appears that what the

From http://www.worldsciencefestival.com/programs/holographic_world/ http://www.worldsciencefestival.com/programs/holographic_wor... it appears that what the physicists mean is just that two systems that start different will forever remain different. So, maybe the thought is, otherwise, when the two systems became the same, could just reverse time back to where they should split into two different systems and would get a contradiction, that is, not know how to make the split. Maybe.