  In this paper we calculated the spectral dimension of loop quantum gravity
(LQG) using the scaling property of the area operator spectrum on spin-network
states and using the scaling property of the volume and length operators on
Gaussian states. We obtained that the spectral dimension of the spatial section
runs from 1.5 to 3, and under particular assumptions from 2 to 3 across a 1.5
phase when the energy of a probe scalar field decreases from high to low energy
in a fictitious time T. We calculated also the spectral dimension of space-time
using the scaling of the area spectrum operator calculated on spin-foam models.
The main result is that the effective dimension is 2 at the Planck scale and 4
at low energy. This result is consistent with two other approaches to non
perturbative quantum gravity: "causal dynamical triangulation" and
"asymptotically safe quantum gravity". We studied the scaling properties of all
the possible curvature invariants and we have shown that the singularity
problem seems to be solved in the covariant formulation of quantum gravity in
terms of spin-foam models. For a particular form of the scaling (or for a
particular area operator spectrum) all the curvature invariants are regular
also in the Trans-Planckian regime.
