Since there exists no acceptable proof that the universe is expanding, there can be no proof that the Big Bang occurred. The radiation detected by Penzias and Wilson of Bell Labs in 1965 is assumed to be residual radiation from the Big Bang. There can be no proof that such is the case. If we consider the energy loss from photons deflected by gravitational fields to provide the red shift in the spectrum, the lost energy must be accounted for. Calculation indicates that the radiation detected by Penzias and Wilson lies within the range of wavelengths to be expected from photon deflections.
Cosmology is the realm of the safest human endeavor.
Any claim made is not subject to refutation. Thus we can have mass going out of existence or being brought into existence without cause to suit the whim of the investigator. The statement brings to mind the current interpretation of pair production and annihilation of positrons and electrons. The present philosophy is that the interaction of positron and electron results in the annihilation of both particles. This results in the creation of two photons, each one of which carries the original rest energy of one of the particles.