17 Jul
2006
17 Jul
'06
4:34 p.m.
According to Noether, energy conservation is equivalent to time-invariance & other conservation laws are equivalent to other symmetries. So here's the question: the laws of physics, as we currently understand them, imply that _information_ is conserved -- we can run physics movies backwards, so long as enough (i.e., _all_) detail is retained. This appears to be the case even in the face of black holes and quantum spookiness. So what is the corresponding symmetry?