George Gamow (Georgiy Antonovich Gamov)

George Gamow

In the early 20th century, radioactive materials were known to have characteristic exponential decay rates, or half-lives. At the same time, radiation emissions were known to have certain characteristic energies. By 1928, Gamow in Göttingen had solved the theory of the alpha decay of a nucleus via tunnelling, with mathematical help from Nikolai Kochin. The problem was also solved independently by Ronald W. Gurney and Edward U. Condon. Gurney and Condon did not, however, achieve the quantitative results achieved by George Gamow. Classically, the particle is confined to the nucleus because of the high energy requirement to escape the very strong nuclear potential well. Also classically, it takes an enormous amount of energy to pull apart the nucleus, an event that would not occur spontaneously. In quantum mechanics, however, there is a probability the particle can “tunnel through” the wall of the potential well and escape. Gamow solved a model potential for the nucleus and derived from first principles a relationship between the half-life of the alpha-decay event process and the energy of the emission, which had been previously discovered empirically and was known as the Geiger–Nuttall law. Some years later, the name Gamow factor or Gamow–Sommerfeld factor was applied to the probability of incoming nuclear particles tunnelling through the electrostatic Coulomb barrier and undergoing nuclear reactions. George Gamow worked at a number of Soviet establishments before deciding to flee the Soviet Union because of increased oppression. In 1931, he was officially denied permission to attend a scientific conference in Italy. Also in 1931, he married Lyubov Vokhmintseva (Russian: Любовь Вохминцева), another physicist in Soviet Union, whom he nicknamed “Rho” after the Greek letter. Gamow and his new wife spent much of the next two years trying to leave the Soviet Union, with or without official permission. Niels Bohr and other friends invited Gamow to visit during this period, but Gamow could not get permission to leave.

George Gamow later said that his first two attempts to defect with his wife were in 1932 and involved trying to kayak: first a planned 250-kilometer paddle over the Black Sea to Turkey, and another attempt from Murmansk to Norway. Poor weather foiled both attempts, but they had not been noticed by the authorities. In 1933 Gamow was suddenly granted permission to attend the 7th Solvay Conference on physics, in Brussels. He insisted on having his wife accompany him, even saying that he would not go alone. Eventually the Soviet authorities relented and issued passports for the couple. The two attended and arranged to extend their stay, with the help of Marie Curie and other physicists. Over the next year, Gamow obtained temporary work at the Curie Institute, University of London, and University of Michigan. George Gamow led the development of the hot “big bang” theory of the expanding universe. He was the earliest to employ Alexander Friedmann’s and Georges Lemaître’s non-static solutions of Einstein’s gravitational equations describing a universe of uniform matter density and constant spatial curvature. Gamow’s crucial advance would provide a physical reification of Lemaître’s idea of a unique primordial quantum. Gamow did this by assuming that the early universe was dominated by radiation rather than by matter. Most of the later work in cosmology is founded in Gamow’s theory. He applied his model to the question of the creation of the chemical elements  and to the subsequent condensation of matter into galaxies, whose mass and diameter he was able to calculate in terms of the fundamental physical parameters, such as the speed of light c, Newton’s gravitational constant G, Sommerfeld’s fine-structure constant α, and Planck’s constant h.

George Gamow’s interest in cosmology arose from his earlier interest in energy generation and element production and transformation in stars. This work, in turn, evolved from his fundamental discovery of quantum tunneling as the mechanism of nuclear alpha decay, and his application of this theory to the inverse process to calculate rates of thermonuclear reaction. At first, Gamow believed that all the elements might be produced in the very high temperature and density early stage of the universe. Later, he revised this opinion on the strength of compelling evidence advanced by Fred Hoyle et al. that elements heavier than lithium are largely produced in thermonuclear reactions in stars and in supernovae. Gamow formulated a set of coupled differential equations describing his proposed process and assigned, as a PhD. dissertation topic, his graduate student Ralph Alpher the task of solving the equations numerically. These results of Gamow and Alpher appeared in 1948 as the αβγ paper (on which Hans Bethe’s name also appears.). Bethe later referred to this paper as being “wrong”. Before his interest turned to the question of the genetic code, Gamow published about twenty papers on cosmology. The earliest was in 1939 with Edward Teller on galaxy formation, followed in 1946 by the first description of cosmic nucleosynthesis. He also wrote many popular articles as well as academic textbooks.

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 point at which they became equal. In this paper Gamow determined the density of the relict background radiation from which a present temperature of 7K is trivially predicted – a value slightly more than twice the presently accepted value. In 1967 he published a reminder and recapitulation of his own work as well as that 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, for which Gamow, Alpher and Herman felt that they did not receive the credit they deserved for their prediction of its existence and source. George 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.

After the discovery of the structure of DNA in 1953 by Francis Crick, James Watson, Maurice Wilkins and Rosalind Franklin, Gamow attempted to solve the problem of how the order of the four different kinds of bases (adenine, cytosine, thymine and guanine) in DNA chains could control the synthesis of proteins from amino acids. Crick has said that Gamow’s suggestions helped him in his own thinking about the problem. As related by Crick, George Gamow suggested that the twenty combinations of four DNA bases taken three at a time corresponded to the twenty amino acids that form proteins. This led Crick and Watson to enumerate the twenty amino acids common to proteins. Gamow’s contribution to solving the problem of genetic coding gave rise to important models of biological degeneracy. The specific system proposed by Gamow (known as “Gamow’s diamonds”) was incorrect, as 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 genetic code is non-overlapping and degenerate, and changing the order of a combination of bases does change the amino acid. In 1954, Gamow and Watson co-founded the RNA Tie Club, a discussion group of leading scientists concerned with the problem of the genetic code. In his own autobiographical writings, Watson later acknowledged Gamow’s ideas and colorful personality as a “zany”, card-trick playing, limerick-singing, booze-swilling, practical–joking “giant imp”. On August 19, 1968, George Gamow died at age 64 in Boulder, Colorado and was buried there in Green Mountain Cemetery.

Born

  • March, 04, 1904
  • Odessa, Russia

Died

  • August, 19, 1968
  • USA
  • Boulder, Colorado

Cemetery

  • Green Mountain Cemetery
  • Boulder, Colorado
  • USA

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