- #1
olliemath
- 34
- 0
I think this is the right forum for this.. are there any physical reasons to assume the evolution of a quantum system is given by a group of unitaries rather than a semigroup of isometries (or, if you're in the Heisenberg picture, group of automorphisms rather than semigroup of endomorphisms)?
In all the baby examples I've seen (particle in a box, field in a steady state universe..) the unitary formulation is natural, but looking at what happens near t=0 in our universe surely keeping a fully reversible evolution isn't option? In particular being able to reverse to t<0 seems a bit nonsensical? Would there be any drastic physical consequences if I assumed my evolution was isometric/endomorphic? _O
(p.s. I'm a mathematician, so I may be missing the obvious here!)
In all the baby examples I've seen (particle in a box, field in a steady state universe..) the unitary formulation is natural, but looking at what happens near t=0 in our universe surely keeping a fully reversible evolution isn't option? In particular being able to reverse to t<0 seems a bit nonsensical? Would there be any drastic physical consequences if I assumed my evolution was isometric/endomorphic? _O
(p.s. I'm a mathematician, so I may be missing the obvious here!)