| George Gamow | |
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George Gamow
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| Born | March 4, 1904 (o.s. February 20, 1904) Odessa, Russian Empire |
| Died | August 19, 1968 (aged 64) Boulder, Colorado, United States |
| Citizenship | Soviet Union, United States |
| Nationality | Russian |
| Fields | Physicist, science writer |
| Institutions | University of Göttingen Niels Bohr Institute Cavendish Laboratory The George Washington University University of California, Berkeley University of Colorado at Boulder |
| Doctoral advisor | Alexander Friedmann |
| Doctoral students | Ralph Asher Alpher |
| Known for | Cosmic microwave background radiation, quantum tunnelling, Big Bang |
| Notable awards | Kalinga Prize (1956) |
George Gamow (Russian pronunciation: [ˈɡaməf]; March 4 [O.S. February 20] 1904 – August 19, 1968), born Georgiy Antonovich Gamov (Russian: Георгий Антонович Гамов), was a Russian-born theoretical physicist and cosmologist. He discovered alpha decay via quantum tunneling and worked on radioactive decay of the atomic nucleus, star formation, stellar nucleosynthesis and Big Bang nucleosynthesis (which he collectively called nucleocosmogenesis), the cosmic microwave background, and genetics.
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Gamow was born in the city of Odessa, Russian Empire (now in Ukraine) to mixed Russian-Ukrainian parents. His father taught Russian language and literature in high school, and his mother taught geography and history at a school for girls. In addition to Russian, Gamow learned to speak some French from his mother, and German from a tutor. Gamow did not learn fluent English until his college years and later. Most of his early publications were in German or Russian, but he later switched to writing in English for both technical papers and for the lay audience.
He was educated at the Novorossiya University in Odessa (1922–23) and at the University of Leningrad (1923–1929). Gamow studied under Alexander Friedmann for some time in Leningrad, until Friedmann died in 1925. At the University, Gamow made friends with three other students of theoretical physics, Lev Landau, Dmitri Ivanenko, and Matvey Bronshtein (who was later arrested in 1937 and executed in 1938 by the Soviet regime). The four formed a group known as the Three Musketeers which met to discuss and analyze the ground-breaking papers on quantum mechanics published during those years.
On graduation, he worked on quantum theory in Göttingen, where his research into the atomic nucleus provided the basis for his doctorate. He then worked at the Theoretical Physics Institute of the University of Copenhagen, from 1928 to 1931, with a break to work with Ernest Rutherford at the Cavendish Laboratory, Cambridge. He continued to study the atomic nucleus (proposing the "liquid drop" model), but also worked on stellar physics with Robert Atkinson and Fritz Houtermans.
In 1931 Gamow was elected a corresponding member of the Academy of Sciences of the USSR at age 28 — one of the youngest in the history of this organization.[1][2][3] During the period 1931-1933, George Gamow worked in the Physical Department of the Radium Institute (Leningrad) headed by Vitaly Khlopin. Under the guidance and direct participation of Igor Kurchatov, Lev Mysovskii and George Gamow, Europe's first cyclotron was designed. In 1932, George Gamow and Lev Mysovskii submitted a draft design for consideration by the Academic Council of the Radium Institute, which approved it. The cyclotron was not completed until 1937.[4][5]
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 had solved the theory of the alpha decay of a nucleus via tunnelling, with mathematical help from Nikolai Kochin.[6][7] The problem was also solved independently by Ronald W Gurney and Edward U Condon.[8][9] Gurney and Condon did not, however, achieve the quantitative results achieved by 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.[10] Some years later, the name Gamow factor or Gamow-Sommerfeld Factor was applied to the probability of incoming nuclear particles tunneling through the electrostatic Coulomb barrier and undergoing nuclear reactions.
Gamow worked at a number of Soviet establishments before deciding to flee Russia because of increased oppression. In 1931, he was officially denied permission to attend a scientific conference in Italy. Also in 1931, he married Lyubov Vokhminzeva (nicknamed "Rho"), another physicist in Russia. Gamow and his new wife spent much of the next 2 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.
Gamow later claimed 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 for himself to attend the first Solvay Conference for nuclear physicists 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.
In 1934, Gamow and his wife moved to the United States. He became a professor at George Washington University (GWU) in 1934, and recruited physicist Edward Teller from London to join him at GWU. In 1936, Gamow and Teller published what became known as the "Gamow-Teller selection rule" for beta decay. During his time in Washington, Gamow would also publish major scientific papers with Mario Schenberg and Ralph Alpher. By the late 1930s, Gamow's interests had turned towards astrophysics and cosmology.
In 1935, Gamow's son, Igor Gamow was born. George Gamow became a naturalized American in 1940. He would retain his formal association with GWU until 1956.
During World War II, Gamow did not work directly on the Manhattan Project producing the atomic bomb, in spite of his knowledge of radioactivity and nuclear fusion. He continued to teach physics at GWU, and consulted for the Navy.
Gamow was interested in the processes of stellar evolution and the early history of the solar system. In 1945, he co-authored a paper supporting work by German theoretical physicist Carl Friedrich von Weizsäcker on planetary formation in the early solar system.[11] Gamow published another paper in the British journal Nature in 1948, in which he developed equations for the mass and radius of a primordial galaxy (which typically contains about one hundred billion stars, each with a mass comparable with that of the sun).
Gamow produced an important cosmogony paper with his student Ralph Alpher, which was published as "The Origin of Chemical Elements" (Physical Review, April 1, 1948). This paper became known as the Alpher-Bethe-Gamow theory. Gamow had the name of Hans Bethe listed on the article as "H. Bethe, Cornell University, Ithaca, New York" to make a pun on the first three letters of the Greek alphabet, alpha, beta and gamma. Bethe was also known for his sense of humor, but had no other role in the α-β-γ paper, and his name had been added without his knowledge. Gamow's lifetime interest in playing pranks, punning, and doggerel verse come across in some of his popular writings, notably his Mr. Tompkins... series of books (1939–1967).
The influential Alpher-Bethe-Gamow paper outlined how the present levels of hydrogen and helium in the universe could be largely explained by reactions that occurred during the "Big Bang". This lent theoretical support to the Big Bang theory, although it did not explain the presence of elements heavier than helium (this was later explained by Fred Hoyle).
In the paper, no estimate of the strength of the present day residual cosmic microwave background radiation (CMB) was made. But shortly thereafter, Alpher and Robert Herman predicted that the afterglow of the big bang would have cooled down after billions of years, filling the universe with a radiation 5 degrees above absolute zero.
Astronomers and scientists did not make any effort to detect this background radiation at that time, due to both a lack of interest and the immaturity of microwave observation. Consequently, Alpher and Herman's prediction in support of the big bang was not substantiated until 1964, when Arno Penzias and Robert Wilson made the accidental discovery, for which they were awarded the Nobel Prize in Physics in 1978. Their work determined that the universe's background radiation was 2.7 degrees above absolute zero, just 2.3 degrees lower than the 1948 prediction.
After the discovery of the structure of DNA in 1953 by Francis Crick and James D. Watson, 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.[12] Crick has said[13] that Gamow's suggestions helped him in his own thinking about the problem. As related by Crick,[14] Gamow suggested that the twenty combinations of four DNA bases taken three at a time correspond to twenty amino acids used to form proteins. This led Crick and Watson to enumerate the twenty amino acids which are common to most proteins.
However 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 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.
After 1954 Gamow was involved in the RNA Tie Club, a discussion group of leading scientists concerned with the problem of the genetic code. One of Gamow's colleagues in the Club was Nobel prize winner James D. Watson, co-discoverer of DNA, who acknowledges Gamow in his own autobiographical writings.[15]
Gamow worked at George Washington University from 1934 until 1954, when he became a visiting professor at the University of California, Berkeley. In 1956, he moved to the University of Colorado at Boulder, where he remained for the rest of his career. Also in 1956, he divorced his first wife. Gamow later married Barbara Perkins (an editor for one of his publishers) in 1958.
In 1959, Gamow, Hans Bethe, and Victor Weisskopf publicly supported the re-entry of Frank Oppenheimer into teaching college physics at the University of Colorado, as the Red Scare began to fade. While teaching there, Oppenheimer became increasingly interested in teaching science through simple hands-on experiments, eventually moving on to found the Exploratorium in San Francisco.
Gamow continued his teaching at the University of Colorado at Boulder, and focused increasingly on writing textbooks and books on science for the general public. On August 19, 1968, Gamow died unexpectedly at age 64 in Boulder, Colorado, and was buried there in Green Mountain Cemetery. The physics department tower at the University of Colorado at Boulder is named after him.
Gamow was a highly successful science writer, with several of his books still in print a half-century after their initial appearance. As an educator, Gamow recognized and emphasized fundamental principles that were unlikely to become obsolete, even as the pace of science and technology accelerated. He also conveyed a sense of excitement with the revolution in physics and other scientific topics of interest to the common reader. Gamow himself prepared the illustrations for his books, which added a new dimension to and complemented what Gamow intended to convey in the text. Wherever it was essential, he was unafraid to introduce mathematics, but he tried to avoid scaring off potential readers with too many equations that did not illustrate essential points.
In 1956, he was awarded the Kalinga Prize by UNESCO for his work in popularizing science with his Mr. Tompkins... series of books (1939–1967), his book One, Two, Three...Infinity, and other works.
Gamow was working on a textbook entitled Basic Theories in Modern Physics, with Richard Blade, but it was not completed before he died. He also had worked on a book entitled My World Line: An Informal Autobiography, which was published posthumously in 1970.
Throughout these books, Mr. Tompkins is introduced as "C. G. H. Tompkins" to emphasize the notion of cGħ physics.
