Gamow , George

(1904–1968) Ukrainian–American physicist

Gamow was born the son of a teacher at Odessa, now in Ukraine. He was educated at the University of Leningrad where he obtained his doctorate in 1928 and later served as professor of physics (1931–34). Before his move to America in 1934 he spent long periods at Göttingen, Copenhagen, and Cambridge, England, the major centers of the revolution then taking place in physics. In America he spent his career as professor of physics at George Washington University (1934–55) and then at the University of Colorado (1956–68).

Gamow made many contributions to nuclear and atomic physics, but is mainly noted for his work on interesting problems in cosmology and molecular biology.

In cosmology he revised and extended the big-bang theory of the creation of the universe (first formulated by Georges Lemaître). This postulates that the universe expanded from a single point in space and time. It was first announced in Gamow's famous ‘alpha beta gamma’ paper in 1948, which he wrote in collaboration withRalph Alpher (1921––sp;–sp;) and Hans Bethe. A fuller account was later published by Gamow in his Creation of the Universe(1952). Gamow dated the expansion to about 17 billion years ago, probably the result of an earlier contraction. The difficulty with any such theory was in accounting for the formation of the chemical elements. He supposed the primeval atom to consist of ‘Ylem’, an old word used by Gamow to refer to a mixture of protons, electrons, and neutrons. Using the conditions of temperature and density prevailing in the first half hour of the universe's history he tried to work out ways in which the elements could be formed by nuclear aggregation. There was no difficulty in showing that ¹H, ²H, ³H, ³He, and ⁴He would be formed but at that point he could see no way to advance the chain further, for there is no stable element with an atomic weight of 5. Add either a proton or a neutron to the nucleus of ⁴He and either ⁵Li or ⁵He will be formed, both of which are unstable and decay in less than 10^–20 sec back to the original ⁴He.

The only solution was to suppose that more than one particle collided with the ⁴He nucleus simultaneously but, as Gamow realized, the universe by this time would be insufficiently dense and hot enough to permit such collisions to occur with the required frequency. He was therefore forced to conclude in 1956 that most of the heavy elements have been formed later in the hot interior of stars. One prediction that did emerge from his work and was to have important consequences for cosmology was his claim that the original explosion would produce a uniform radiation background; the discovery of such radiation in 1964 by Arno Penzias and Robert Wilson did more than anything else to stimulate interest once more in Gamow's theory.

Gamow later moved from showing how the universe began to the no less interesting question of how life began. He was quick to see the significance of the DNA model proposed by James Watson and Francis Crick in 1953. The problem was to show how the sequences of the four nucleic acid bases that constitute the DNA chain could control the construction of proteins, which may be made from 20 or more amino acids. Gamow had the insight to see that the bases must contain a code for the construction of amino acids. But the question of how this worked still remained. It could not be one base to one amino acid for then there would be only four amino acids. Nor would two bases be sufficient for they could produce only 4 × 4 = 16 amino acids. It would therefore need a sequence of three bases to produce one amino acid, a language with a capacity of 4 × 4 × 4 = 64 words, which was more than adequate for the construction of all proteins. Gamow also produced convincing arguments to show that the code is not overlapping.

The work on DNA allowed Gamow to indulge his passion for science fantasy. He founded the RNA tie club for which he actually designed a tie. It was restricted to 20 members, one for each amino acid. Each member took the name of one of the acids – Gamow was ‘phe’ (the usual abbreviation for phenylalanine) while Crick was ‘tyr’ (tyrosine). Meetings were held, information was exchanged, and considerable progress was made.

Gamow was also known as one of the most successful popular science writers of his day. He wrote many books, most of which are still in print, which convey much of the excitement of the revolution in physics that he lived through.