The model of low-energy quantum gravity leads to small additional effects having essential cosmological consequences: redshifts of remote objects and the additional dimming of them may be interpreted without any expansion of the Universe and without dark energy. The theoretical luminosity distance of the model fits the observational Hubble diagrams with high confidence levels. In the model, the ratio H(z)/(1 + z) should be equal to the Hubble constant. The constancy of this ratio is confirmed with high probabilities by fitting the compilation of H(z) observations. A deceleration of massive bodies due to forehead and backhead collisions with gravitons is re-computed here.