Alpher-Bethe-Gamow paper

Alpher-Bethe-Gamow paper

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In physical cosmology
Physical cosmology
Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. For most of human history, it was a branch of metaphysics and religion...

, the Alpher–Bethe–Gamow paper, or αβγ paper, was created by Ralph Alpher, then a physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 PhD
PHD
PHD may refer to:*Ph.D., a doctorate of philosophy*Ph.D. , a 1980s British group*PHD finger, a protein sequence*PHD Mountain Software, an outdoor clothing and equipment company*PhD Docbook renderer, an XML renderer...

 student, and his advisor George Gamow
George Gamow
George Gamow , born Georgiy Antonovich Gamov , 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, Big Bang nucleosynthesis, cosmic microwave...

. The work, which would become the subject of Alpher's PhD dissertation, argued that the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 would create hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

 and heavier elements in the correct proportions to explain their abundance in the early universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

. While the original theory neglected a number of processes important to the formation of heavy elements, subsequent developments showed that Big Bang nucleosynthesis
Big Bang nucleosynthesis
In physical cosmology, Big Bang nucleosynthesis refers to the production of nuclei other than those of H-1 during the early phases of the universe...

 is consistent with the observed constraints on all primordial elements.

Formally titled "The Origin of Chemical Elements", it was published in the April 1948 issue of Physical Review
Physical Review
Physical Review is an American scientific journal founded in 1893 by Edward Nichols. It publishes original research and scientific and literature reviews on all aspects of physics. It is published by the American Physical Society. The journal is in its third series, and is split in several...

.

Bethe's name


Gamow humorously decided to add the name of his friend—the eminent physicist Hans Bethe
Hans Bethe
Hans Albrecht Bethe was a German-American nuclear physicist, and Nobel laureate in physics for his work on the theory of stellar nucleosynthesis. A versatile theoretical physicist, Bethe also made important contributions to quantum electrodynamics, nuclear physics, solid-state physics and...

—to this paper in order to create the whimsical author list of Alpher, Bethe, Gamow, a play on the Greek letters α, β
Beta (letter)
Beta is the second letter of the Greek alphabet. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represents the voiced labiodental fricative ....

, and γ (alpha, beta, gamma). Bethe was listed in the article as "H. Bethe, Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

, Ithaca, New York
Ithaca, New York
The city of Ithaca, is a city in upstate New York and the county seat of Tompkins County, as well as the largest community in the Ithaca-Tompkins County metropolitan area...

." In his 1952 book, The Creation of the Universe
The Creation of the Universe
The Creation of the Universe is Lou Reed's Metal Machine Trio's first album. Metal Machine Trio is Lou Reed's band that was formed in 2008 with Ulrich Krieger and Sarth Calhoun to play music inspired by Reed's 1975 album Metal Machine Music. The first concerts of the group were on October 2 and 3,...

, Gamow explained Hans Bethe's association with the theory thus:


After this, Bethe did work on big bang nucleosynthesis
Big Bang nucleosynthesis
In physical cosmology, Big Bang nucleosynthesis refers to the production of nuclei other than those of H-1 during the early phases of the universe...

.

Alpher, at the time only a graduate student, was generally dismayed by the inclusion of Bethe's name on this paper. He felt that the inclusion of another eminent physicist would overshadow his personal contribution to this work and prevent him from receiving proper recognition for such an important discovery. He expressed resentment over Gamow's whimsy as late as 1999.

Main shortcoming of the theory


The theory originally proposed that all atomic nuclei
Atomic nucleus
The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The...

 are produced by the successive capture of neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...

s, one mass unit at a time. However, later study challenged the universality of the successive capture theory. No element was found to have a stable isotope with an atomic mass of five or eight. Physicists soon noticed that these mass gaps would hinder the production of elements beyond helium. Just as it's impossible to climb a staircase one step at a time when one of the steps is missing, this discovery meant that the successive capture theory could not account for higher elements.

It was eventually recognized that most of the heavy elements observed in the present universe
Abundance of the chemical elements
The abundance of a chemical element measures how relatively common the element is, or how much of the element is present in a given environment by comparison to all other elements...

 are the result of stellar nucleosynthesis
Stellar nucleosynthesis
Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the elements heavier than hydrogen. Some small quantity of these reactions also occur on the stellar surface under various circumstances...

 in stars, a theory largely developed by Bethe.

However, the Alpher–Bethe–Gamow theory does correctly explain the relative abundances of the isotopes of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 and helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

. Taken together, these account for more than 99% of the baryon
Baryon
A baryon is a composite particle made up of three quarks . Baryons and mesons belong to the hadron family, which are the quark-based particles...

ic mass of the universe. Today, nucleosynthesis is widely considered to have taken place in two stages: formation of hydrogen and helium according to the Alpher–Bethe–Gamow theory, and stellar nucleosynthesis of higher elements according to Bethe's later theories.