What is the Alpher-Bethe-Gamow Paper?

Question: What is the Alpher-Bethe-Gamow Paper?


The Alpher-Bethe-Gamow paper (or alpha-beta-gamma paper) is a 1948 paper published in the journal Physical Review. The actual title of the paper was "The Origin of Chemical Elements" and it laid out the basic principles of nucleosynthesis, or the formation of elements heavier than hydrogen through nuclear fusion, in the early universe shortly following the Big Bang.

Here a link to the article itself, in PDF format.

The Alphabetical Paper

The paper gets its humorous name from the three people listed as authors: Ralph Alpher, Hans Bethe, and George Gamow. The funny thing, though, is that Bethe wasn't even involved in the writing of the paper. Gamow came up with the general principles and let his Ph.D. student, Ralph Alpher, do the bulk of the heavy lifting in working on the paper. (It's good to have doctoral students.) But, as described by physicist and science writer Michio Kaku in Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos:

When the paper was finished, [Gamow] couldn't resist a practical joke. He put physicist Hans Bethe's name on the paper without his permission, and it became the celebrated alpha-beta-gamma paper.

This is a popular story and shows up in a number of popular physics books, such as Stephen Hawking's A Brief History of Time and James Kakalios' The Amazing Story of Quantum Mechanics.

Gamow himself described the event in his 1952 book, The Creation of the Universe, with his usual wit and style:

The results of these calculations were first announced in a letter to The Physical Review, April 1, 1948. This was signed Alpher, Bethe, and Gamow, and is often referred to as the 'alphabetical article.' It seemed unfair to the Greek alphabet to have the article signed by Alpher and Gamow only, and so the name of Dr. Hans A. Bethe (in absentia) was inserted in preparing the manuscript for print. Dr. Bethe, who received a copy of the manuscript, did not object, and, as a matter of fact, was quite helpful in subsequent discussions. There was, however, a rumor that later, when the alpha, beta, gamma theory went temporarily on the rocks, Dr. Bethe seriously considered changing his name to Zacharias.

The close fit of the calculated curve and the observed abundances is shown in Fig. 15, which represents the results of later calculations carried out on the electronic computer of the National Bureau of Standards by Ralph Alpher and R. C. Herman (who stubbornly refuses to change his name to Delter.)

The Paper's Science

The paper essentially laid the groundwork for the field of Big Bang nucleosynthesis, showing that it was possible to create heavier elements from fusing hydrogen together in the heat following the Big Bang and that (at least for helium and some other lighter elements) this basically accounted for the distribution of elements observed. This got Gamow and Alpher thinking about the heat of the early universe, so they calculated a value for the cosmic microwave background (CMB) radiation, which would later be experimentally confirmed (but that's a story for another time).

Gamow and Alpher didn't quite achieve their goal, though. It had been Gamow's theory that this approach would ultimately result in the creation of all heavier elements in the universe, but it was nowhere close. The approach never quite worked for elements larger than 8-particles (that is, 8 protons and neutrons total in the nucleus). In fact, 5-particle and 8-particle combinations proved unstable in this approach, so it only worked to explain the creation of elements with very small numbers of particles in the nucleus. It would require later work in stellar nucleosynthesis to explain the creation of heavier elements.

Amusingly, one of the key figures in developing stellar nucleosynthesis was Hans Bethe, who wrote a 1939 paper "Energy Production in Stars," that established the way fusion in a star could produce heavier elements, and would receive a 1967 Nobel Prize for this work. Bethe built on earlier suggestions from Arthur Eddington. The theory of stellar nucleosynthesis was later developed more fully and refined in greater detail by Fred Hoyle ... who, ironically, was the one who condescendingly coined the term "Big Bang" to refer to the cosmological model that he considered foolish. This all just goes to show what a curious, circular, and inter-connected world the physics community can sometimes be.