 In 1948, he published a paper dealing with an attenuated version of the coupled set of equations describing the production of the proton and the deuteron from thermal neutrons.By means of a simplification and using the observed ratio of hydrogen to heavier elements, he was able to obtain the density of matter at the onset of nucleosynthesis and from this the mass and diameter of the early galaxies.In 1953 he produced similar results, but this time based on another determination of the density of matter and radiation, at the time at which they became equal.