cosa ne pensate?

From: Patrizio <patrizio.pan-2002_at_libero.it>
Date: 14 Sep 2006 01:30:10 -0700

Chiarimento: questa e' una risposta tipica di un certo poster
a quelli che (piu' o meno velatamente) pongono quesiti sulla RR
in sci.physics.* NG. In parentesi quadre i miei commenti o richieste
di spiegazione.

''Special Relativity is physics on a topologically trivial Lorentzian
manifold [ecco qui che vuol dire esattamente 'manifold', e perche'
parla di 'trivial' ?]
with a metric whose curvature tensor is zero. This is a
perfectly diffeomorphism-invariant condition and does not require
any particular coordinate choice. It is invariant under
the full group of diffeomorphisms. The Poincare group is
the group of *isometries* of the metric in special relativity.

The Special Relativity metric is *non-dynamical* (unlike GR). It
defines the coupling *constants* of your theory. [anche qui un
chiarimento sarebbe di non poco aiuto] If you change the
metric in any nontrivial way you are changing your theory [perche'?].
An operation can only be called a "symmetry" of a special-relativistic
(non-gravitational) theory if it preserves the metric, and therefore
the symmetry of special-relativistic theories is the Poincare group
only. General Relativity (gravitation) has a dynamic metric.

NIM A 355 537 (1995)
Physics Letters B 328 103 (1994)
Physical Review Letters 64 1697 (1990)
Physical Review Letters 39 1051 (1977)
Physical Review 135 B1071 (1964)
Physics Letters 12 260 (1964)
Europhysics Letters 56(2) 170-174 (2001)
General Relativity and Gravitation 34(9) 1371 (2002)''

Grazie dell'attenzione,

Ciao
Patrizio
Received on Thu Sep 14 2006 - 10:30:10 CEST