Cosmologist Sean Carroll: Arrow of Time

Why does the universe have a direction?  Why are some events are reversible and some are unidirectional? And what does this mean for the Epic of Evolution?  Cosmologist Sean Carroll tells us about the physics of the Arrow of Time.  Filmed November, 2009.  Why do some things change and some things stay the same?

http://www.ted.com/talks/sean_carroll_on_the_arrow_of_time.html