  The importance of the tomographic approach is that either in quantum
mechanics as in classical mechanics the state of a physical system is expressed
with the same family of functions, the tomograms. The extension of this
procedure to quantum cosmology is straightforward. But instead of using the
tomographic representation, we use tomograms to analyze the properties of the
quantum and classical universes, starting from the wave functions in quantum
cosmology and the phase space distribution in classical cosmology. In this
paper we resume the properties of the tomographic approach introduced in
previous papers.
  Then we study and discuss the properties of the initial conditions introduced
by Hartle and Hawking and by Vilenkin and Linde and we study their classical
transition. It results that a possible reason for the quantum to classical
transition is the decay of the cosmological constant from the Planck scale to
the present one. So that the Cosmological Constant Problem becomes a crucial
topic in study of the evolution of the universe.
