5 Stable Structures, Hilbert Sectors, Phases
29
tions of groups, spontaneous symmetry breaking, pure phases, superselection rules,
etc., at the level of classical equations.
24
The occurrence of disjoint physical worlds or phases is a typical feature of
infinitely extended systems, like, e.g. those defined by the thermodynamical limit
in Statistical Mechanics, where one cannot go from one phase to another by essentially local operations.
25
24 F. Strocchi, Lectures at the Workshop on Recent Advances in the Theory of Evolution Equations,
ICTP Trieste 1979, published in Topics in Functional Analysis 1980-81, Scuola Normale Superiore,
Pisa 1982; contribution to the Workshop on Hyperbolic Equations (1987), published in Rend. Sem.
Mat. Univ. Pol. Torino, Fascicolo speciale 1988, pp. 231–250.
25 The physical relevance of locality has been emphasized by R. Haag and D. Kastler, J. Math. Phys.
5, 848 (1964), see also R. Haag, loc. cit. (see footnote 17).
29
tions of groups, spontaneous symmetry breaking, pure phases, superselection rules,
etc., at the level of classical equations.
24
The occurrence of disjoint physical worlds or phases is a typical feature of
infinitely extended systems, like, e.g. those defined by the thermodynamical limit
in Statistical Mechanics, where one cannot go from one phase to another by essentially local operations.
25
24 F. Strocchi, Lectures at the Workshop on Recent Advances in the Theory of Evolution Equations,
ICTP Trieste 1979, published in Topics in Functional Analysis 1980-81, Scuola Normale Superiore,
Pisa 1982; contribution to the Workshop on Hyperbolic Equations (1987), published in Rend. Sem.
Mat. Univ. Pol. Torino, Fascicolo speciale 1988, pp. 231–250.
25 The physical relevance of locality has been emphasized by R. Haag and D. Kastler, J. Math. Phys.
5, 848 (1964), see also R. Haag, loc. cit. (see footnote 17).