  Particle acceleration in the dynamically evolving environment of Supernova
Remnants is discussed in the framework of a genuinely time-dependent nonlinear
theory, assuming spherical symmetry. As a consequence the dependence of
injection on the angle between shock normal and external magnetic field
direction requires a renormalisation of the calculated particle fluxes. The
recent observational results in TeV gamma-rays from such objects are discussed
and found to be consistent with theory. We conclude that for the present
instrumental sensitivities there are no reasons to draw premature negative
conclusions as to the possible origin of the Galactic Cosmic Rays below the
"knee" in Supernova Remnants. In addition, theoretical predictions and
observations are getting very close. Therefore the coming generation of
ground-based and space-borne detectors will decide this basic question of
astrophysics.
