I think I understand it as well as I can, given my lack of natural ability when it comes to physics! I don't think I can agree however... I am sure this all makes sense at the level of physics but I worry about this statement:
'If we accept that the interaction of things in our past have consequences in our now and our future, then - by this symmetry - there are large amounts of stuff in our future that are interacting and affecting our now and our past.'
I am not sure I do accept it - the past shapes the present and the future undoubteldy, but I dont see it as "interacting" with the present and the future as such (matter of characterisation) I don't think say for example whether I chose to stay on at UEA or take a job elsewhere is interacting with my future - it is shaping it - but not interacting with it - because this is only one event that is shaping the future and there might be external events outside of my control which in turn shape the future. There is no certainty about what the future is that it will be interacting with...
I guess these means I am a believer in thermodynamics, which I always thought had to do with flask technology! ;-)