The reduced phase-space description amounts to the identification of the true physical degrees
of freedom of the system. As a rule, for many physical models (and certainly in the case of
gravitational theories) this description is either unavailable or extremely difficult to handle. In these
cases one is forced to learn how to live with the redundant descriptions provided by gauge
theories and how to handle the constraints both at the classical and quantum levels. Finally, it is
important to notice that whenever the reduced phase space can be characterized by means of
a gauge fixing, the quantization ambiguities that may arise do not originate in the different
gauge choices – as long as they are acceptable – but rather in the possibility of having different
quantizations for a given classical model. This is so because from the classical point of view
they are explicit representations of the same abstract object: the reduced phase space [113].
There are several approaches to the quantization of gauge systems that we will briefly discuss
next.
http://www.livingreviews.org/lrr-2010-6 |
Living Rev. Relativity 13, (2010), 6
![]() This work is licensed under a Creative Commons License. E-mail us: |