  As was shown before (Gurzadyan and Kocharyan, 1992, 1993ab) the statistical
properties (exponential mixing) of motion of CMB photon beams in Friedmann
Universe with negative curvature can have definite observable consequences
including the decrease of the CMB anisotropy amplitude after the last
scattering, distortion of images on CMB sky maps. Here we consider one more
consequence concerning the behaviour of temperature autocorrelation function
C(\theta,\beta), where \theta is the modulation (separation) angle, and \beta
the observing beam effective angle. We prove that in the Universe with negative
curvature any spectrum of perturbations at last scattering epoch becomes a
scale-invariant by present time. It is also predicted that the temperature
autocorrelation function should increase while obtained from measurements with
small beam sizes within some mixing beam angle.
