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E.R. Wollman (Bates College)
A seemingly insurmountable objection to cosmological models in which the early universe is cold and the cosmic microwave background radiation (CMBR) is of recent origin is the difficulty accounting for the precisely Planckian spectrum of the CMBR. This objection is addressed in reconsidering a universe composed of initially cold baryonic matter for which the ratio of the lepton number to the baryon number is in the appropriate range near unity such that the neutron-to-proton ratio of the cold high-density state is also near unity. It is known that in this case, fusion during the initial seconds of a Friedmann expansion is very efficient, warming up the matter and turning most of it into heavy elements. A consequence that has apparently gone unnoticed is that when expansion cools the matter back down, condensation into solids is also very efficient. At an expansion time of order 100 years, the gas of heavy elements condenses into solid chunks that grow to sizes in the centimeter range. In other words, matter emerges from this cold early universe in the form of nearly invisible (i.e. dark) ideal microwave thermalizers. Moreover, the number density of these chunks at the present epoch is sufficient to obscure the view beyond redshift z of roughly 3. The fact that hydrogen and helium dominate the apparently small fraction of matter which is visible must be understood in this scenario as a consequence of chemical and gravitational segregation of more and less volatile elements.