  We consider the possible quantum effect for infinite systems produced by
variations of the Planck's constant. Using the algebraic formulation of quantum
theory we study behaviour of states $\omega$ defined as positive, normalized
functionals on the canonical commutation relations algebra (CCR-algebra) under
the changes of the defining relations of the CCR. These defining relations of
the multiplication in the CCR-algebra depend explicitly on the value of the
Planck's constant. We analyse to what extend changes of the $\hbar$ preserve
the original state space (this gives restrictions on the admissible changes of
the Plank's constant) and what properties have original quantum states $\omega$
as states on the new algebra. We answer such questions for the quasi-free
states. We show that any universally invariant state can be interpreted as a
convex combination of Fock states with different values of Planck's constant.
The second important class of states we study are the KMS-states, here the
rescaling alters in a nontrivial way the relevant dynamics. We also show that
it is possible to go beyond the limits restricting the changes of the $\hbar$,
but then one has to restrict the CCR-algebra to a subalgebra.
