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. In this paper, Gamow determined the density of the relict background radiation, from which a present temperature of 7 K was predicted – a value which was slightly more than twice the presently-accepted value. In 1967, he published reminiscences and recapitulation of his own work as well as the work of Alpher and Robert Herman (both with Gamow and also independently of him). This was prompted by the discovery of the cosmic background radiation by Penzias and Wilson in 1965; Gamow, Alpher, and Herman felt that they did not receive the credit they deserved for their theoretical predictions of its existence and source. Gamow was disconcerted by the fact that the authors of a communication explaining the significance of the Penzias/Wilson observations failed to recognize and cite the previous work of Gamow and his collaborators. DNA and RNA In 1953, Francis Crick, James Watson, Maurice Wilkins and Rosalind Franklin discovered the double helix structure of the DNA macromolecule. Gamow attempted to solve the problem of how the ordering of four different bases (adenine, cytosine, thymine and guanine) in DNA chains might control the synthesis of proteins from their constituent amino acids. Crick has said that Gamow's suggestions helped him in his own thinking about the problem. As related by Crick, Gamow observed that the 43 = 64 possible permutations of the four DNA bases, taken three at a time, would be reduced to 20 distinct combinations if the order was irrelevant. Gamow proposed that these 20 combinations might code for the twenty amino acids which, he suggested, might well be the sole constituents of all proteins. Gamow's contribution to solving the problem of genetic coding gave rise to important models of biological degeneracy. The specific system that Gamow was proposing (called "Gamow's diamonds") proved to be incorrect. The triplets were supposed to be overlapping, so that in the sequence GGAC (for example), GGA could produce one amino acid and GAC another, and also non-degenerate (meaning that each amino acid would correspond to one combination of three bases – in any order). Later protein sequencing work proved that this could not be the case; the true