We present a possible way of indirect probing of the
Planck scale effects by the cosmological observations.
Our considerations base on loop quantum cosmology
(LQC) which is the symmetry reduced model of loop
quantum gravity. We show how the standard phase of
cosmic inflation is naturally realized within LQC. We
consider generation of gravitational waves in this model.
Based on this, we present the way to relate LQC effects
with observations of the cosmic microwave background
radiation (CMB). In particular, we investigate the possible
LQC effects on the B-type polarization of the CMB. We
confront the theoretical predictions with the available
observational data and indicate the possible constraints
on the Planck scale physics. We discuss perspectives and
limitations of the proposed approach.
