History of the Big Bang Theory. Gamow, & Early Attempts to Understand the Origin of the Universe. George Gamow was an early advocate of the big bang theory for the origin of the universe. Many of his details were incorrect, but he got the essential idea right.
Abbe Georges Lemaitre first suggested the universe originated from a singular point. George Gamow however developed the big bang theory in additional detail and was one of the first champions of the theory. A tireless science popularizer, he also did much of the early popularizing of the theory. We now know many of his details were incorrect, but they were an excellent first attempt.
Among other important details of the big bang theory, Gamow worked on the origin of the elements. How did the atoms of hydrogen, oxygen, carbon, nitrogen, iron, uranium, and all the other elements we see around us form? In the depths of the great depression, when most people worried about the origin of their next meal, Gamow concerned himself with the origin of the universe and with the ultimate origin of the carbon, and other, atoms in that meal. This work continued through World War II and into the early 1950s.
By the mid 1930s, Gamow had suggested that Lemaitre’s primeval atom was a very hot dense state of matter. He called the primeval matter ylem. Gamow incorrectly thought that initially the ylem was entirely neutrons at a temperature of about 10 billion degrees. When neutrons undergo beta decay, they split into protons and electrons. Gamow thought beta decay formed the protons and electrons in the early universe.
Gamow thought that during these early stages the temperature and density were so high that atomic nuclei often collided with and captured neutrons. These captured neutrons decayed into protons and the electrons escaped from the nuclei. Nuclei with successively larger numbers of protons formed. The number of protons in the nucleus, determines the element, so successively heavier elements formed. Gamow incorrectly theorized that eventually all the naturally occurring elements formed this way during the initial big bang.
Alpha Beta Gamma
A short paper published in the April 1, 1948 issue of Physical Review outlines this process. Gamow did this work with his student, Ralph Alpher, but as the proud owner of an overactive sense of humor Gamow added Hans Bethe (a prominent theoretical physicist) as an additional author. The paper then, in a pun on the Greek alphabet, became the Alpher, Bethe, Gamow paper. Alpher continued this work with Robert Herman, who strangely refused to change his name to Delter for Gamow’s benefit.
Early Computer Calculations
In the early 1950s they used a newly invented computer to make detailed calculations of the reactions needed for Gamow’s ylem to make all the naturally occurring elements. This work was one of the first major scientific problems tackled with electronic computers.
In this day of powerful laptop computers, we tend to forget that in those early days computers filled rooms, programming consisted of manually moving wires into the appropriate plugs, and programming bugs were often six legged biological entities entangled in this wiring.
This attempt to explain the origin of the elements during the big bang from the primeval ylem was only a partial success. We no longer think that the primeval matter was a neutron rich ylem. The details are more complex. More importantly, only the four lightest elements formed during the big bang. Hydrogen and helium as well as trace amounts of lithium and beryllium formed during the big bang. The other 88 naturally occurring elements could not have been made during the big bang. They formed later in stars. So the idea that all 92 elements formed in the big bang was only 4/92 correct.
We have made many changes to details of the big bang theory since Lemaitre and Gamow, but they got the essential idea of the universe expanding from a singular point.