Ludwig et al. derived solar ages up to 22.3 Gyr (2009). The applied Th/Eu ratio is most credible. But the upper limit of the obtained interval is inconsistent with the mainstream-cosmology age of the Universe (about 13.8 Gyr). On the other hand, the Scale-Symmetric Theory (SST) shows that the age of the Universe is about 21.614 +- 0.096 Gyr but due to the duality of relativity (due to the quantum entanglement, the speed of light, c, is the speed in relation to source of light or to a last-interaction object) we cannot see the initial period about 7.75 Gyr of evolution of the protogalaxies/quasars. The calculated time distance to the observed most distant galaxies is 13.866 +- 0.096 Gyr but they are already 7.75 Gyr old. The era of the quasars and the big stars in quasars lasted about 10 Gyr but we can see only the last period about 2.3 Gyr. Due to evolution of the Universe, hydrogen transforms into helium whereas helium transforms into more massive atomic nuclei. It suggests that it can be that with time, mass abundance of helium in relation to hydrogen can slowly decrease. Here, by an analogy to the Stefan-Boltzmann law, we obtain formulae for change in abundance of helium-4 and hydrogen in the expanding Universe. For the invisible primordial Universe we obtain about 1. On the assumption that today abundances are 24.5% for helium and 75.5% for hydrogen (ratio = 3.1; we neglect the other chemical elements), we obtain that for the most distant observed Universe is 2.3 whereas for the end of the era of quasars and big stars is 2.45.