▽Julian B. Barbour ●02/10 00:44 World Science Festival discussion with Brian Greene, in which I emphasise that entropy can only be properly defined in a confined system. In the previous WSF podcast on time (starting from about 10 minutes), Roger Penrose imagines a galaxy in a box in order to argue that gravitational entropy behaves in the opposite way to ordinary entropy. But this purely imaginary box stops the true evolution o
