The cosmic microwave background radiation is routinely cited as evidence for a hot Big Bang. Its near isotropy harmonizes with the cosmological principle. However, in prototypical Big Bang models, all matter originates from a primeval fireball that also emits the light that is redshifted into these microwaves. Since light escapes from its source faster than matter can move, it would need to return for it to still be visible to material observers, but the universe is considered ‘flat’ and non-reflective. This prevents us from observing the redshifted glow of a primeval fireball. This is concealed by considering the light to expand with the ‘Hubble flow’ while disregarding that it would escape at c. This “relic radiation blunder” reflects the assumption that model universes in General Relativity are filled with a spatially homogeneous fluid. For radiation, this becomes inappropriate when it is no longer scattered. What we actually observe remains unexplained. Moreover, current standard cosmology allows an expanding view into a large pre-existing universe, while for some aspects it assumes the universe to have been smaller before. This creates geometric, i.e., “cosmometric” contradictions such as between the observed source of the cosmic microwaves and the much smaller and closer assumed emitting source of the same. The criticism expressed here goes against the ‘hard core’ of an established research program. Experts in the field normally view these cores as untouchable. This attitude blocks foundational advances in science.