The premise of an earlier universe, dominated by radiation, lead to a simulation based in that a decrease in energy of primordial-quanta, eventually yielding matter and a residual Cosmic Microwave Background (CMB) of 0.012% from total energy. Characterization of the latter, in terms of a continuum of energy-space-time quantum dimensioning dynamics, shows that a decrease in energy density of photons, with an increase in their relationship radius vs. time of localization equal to c. This relationship corresponds, with the increment of the cosmic space radius vs. universe time similarly conforming to c, the velocity of light. Parametric down-conversion (PDC), fits as energy conservation mechanism, which allows a continuous renewal of a dissipative potential, by splitting a photon into two of twice the original wavelength. The newly created photons emerge uniformly stretching-out space. Calculation shows that the number of emerging CMB-photons per second per Mpc when linearly aligned corresponds to the value of the Hubble constant (H_0). Recession velocity v=H_0xr as a function of the radius and time of the universe when r=r_U in Mpc units equals velocity of light over H_0 : r_U=c/H_0. Accordingly, the model could by denominated: Energy Space-TIme Relativistic Expansion (E.S.TI.R.E., Spanish) or S.T.R.E.T.CH.: Space-Time Relativistic Expansion Cosmological Hypothesis. PDC photon-splitting by magnification of the space-time locus of photons dominates over the scarce response of CMB to gravitational attraction. Moreover, since their mass in terms of the cosmos total mass is rather insignificant, the curvature of the cosmos could be regarded as CMB-independent near-independent mechanism. The plotting of the PDC continuum of CMB quanta elongation, when scaled vs. the expansionary universe volume, shows a straight line curve. This one represents a continuous thermodynamic-expansionary relationship, in which one photon entering into a PDC cycle, distributes its original energy over a space-time locus incremented 16 times. By analogy, this may be considered a thermodynamic prediction equivalent to “flat”, because any other numerical relationship, curves out of the observed relationship between increments in number of photons and volume of the universe. The particle and radiation roles, may be complementary because CMB would dimension vacuum and galactic recession, whereas the non-continuum quantum structure of matter, would be the dominant effect over the geometric configuration of the universe curvature. Hence, matter by its gravitational attraction, could overcome galactic recession by a uniform CMB-vacuum expansion, and would be driving galaxies into forming cumulus….(Truncated by viXra Admin to < 400 words).