  We provide an alternative approach to the decoherence-by-environment paradigm
in the field of the quantum measurement process and the appearance of a
classical world. In contrast to the decoherence approach we argue that the
transition from pure states to mixtures and the appearance of macro objects
(and macroscopic properties) can be understood without invoking the
measurement-like influence of the environment on the pointer-states of the
measuring instrument. We show that every generic many-body system contains
within the class of microscopic quantum observables a subalgebra of macro
observables, the spectrum of which comprises the macroscopic properties of the
many-body system. Our analysis is based (among other things) on two ingenious
papers by v.Neumann and v.Kampen.
