  A free hermitian conformal field theory is considered in Minkowski, de Sitter
and anti-de Sitter spacetimes. The first part of the paper studies spacetime
inversion and conformal inversion, wherein their role in the field quantization
is elucidated in those spaces. The second part of the paper is concerned with
the non-unitary evolution of detector's state. Several examples of such
processes are provided with a clarification of how the unitarity is preserved
with still having well-known thermal effects.
