George Gamow - Big Bang Nucleosynthesis

Big Bang Nucleosynthesis

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 paper was drawn from Alpher's dissertation work, which he defended approximately six weeks after the publication. The majority of his dissertation work appeared in the Physical Review in December, 1948, following his prediction of the Cosmic Microwave Background Radiation.

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). This paper relied heavily on the mathematical prowess of Ralph A. Alpher and his doctoral dissertation, which he defended to an audience of over 300 at The George Washington University. Gamow had invited Hans Bethe to sit on Alpher's doctoral examination committee. At one time he suggested that part of the motive was to head off any objections Bethe might have to this work, and also that the University traditionally paid travel expenses of external examination committee members. However, the form of this April 1, 1948 paper detracted from the original work of Alpher, influencing correct attribution of the work to Alpher and his doctoral dissertation, as well as some of Alpher's significant work to follow. Gamow's stature, high visibility and reputation overshadowed the original work of Alpher. Yet, it was Alpher's work and mathematical sophistication which turned the study of cosmology into a legitimate field of physical science. Very late in his career, Gamow again submitted a paper prior to receiving corrections from first author Alpher.

In the April 1, 1948 paper, no estimate of the strength of the present day residual cosmic microwave background radiation (CMB) was made; the subject was a mathematical model of nucleosynthesis of the most abundant elements in the universe. But shortly thereafter, Alpher and his colleague at the Johns Hopkins University Applied Physics Laboratory, Robert Herman, published a prediction 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. For three years at minimum Gamow opposed the CMB's validity and conceptualization, according to R. Alpher. Having as his doctoral committee chair a man of Gamow's stature, influenced the young Alpher's career, as his work was attributed to Gamow for decades.

Optical astronomers and early radioastronomers were not keen to devote time to detection of this background radiation in the late 1940s and 1950s. Many factors probably influenced this--lack of interest in what had been a branch of philosophy (cosmology) and the immaturity of microwave observation with radiotelescopes. 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. Historians of science have argued that the 2.7 Kelvin radiation had been observed a number of times, but dismissed because of a lack of interpretive context (i.e., cosmology), or doubts about the signal to noise ratio of early radio astronomical measurements. Two more Nobel prizes in physics were made for work related to accurate observation of the CMB, in 2006, to John C. Mather and George Smoot from data gathered by NASA's Cosmic Microwave Background Explorer (COBE), launched in 1989 with Alpher and Herman in attendance.