The results of a simulation by parametric down-conversion (PDC) fitted observational evidence. This data was plotted in relationship to the radius of the universe in Mpc multiplied by Hubble’s constant (H_0), characterizing expansion as subject to velocity of light (c), functioning as a relativistic causality horizon. PDC allowed describing expansion as a function of the observable increment of photon number. This one multiplied by the increment of the quantum dimensional locus (Compton-volume) equals the increment of the universe volume. The nature and frequency of primordial energy differ by much that of its residual cosmic microwave background (CMB), but the simulation concerns only to relate their frequency by a mathematical treatment, and hereby both may be refer indistinctly. The following theoretical treatment, of the proposed quantum and relativistic parameters, were amalgamated into a single equation and verify by simulation. The plotting of the dimensions of radius of the Universe and the radius of CMB-photon vs time of the Universe and time of localization shows that all this parameters must increment simultaneously, in order to preserve the constants. A sequential cascade of PDC-cycles which by generating photons of lower and lowers energy, could maintain “a continuum of decreasing dissipative potential”. Hence, because the product from a preceding PDC-cycle becomes the substrate for a subsequent one, accumulation of product is prevented, as if were open thermodynamic systems. This state of the system, without any considerable reversibility, would endure until near extinction of the energy of CMB. The continuum of lambda-CMB and its time of localization continuously generate entropy at the level of increment of photons and Compton-volume structuring the arrow of time.