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Einstein and Eddington opposed neutron star concept
These Oppenheimer papers concluding that either neutron stars or black holes could be the outcome of massive star implosion were about as far as physicists could go at that time. However, the most prominent physicist of the time, Albert Einstein, and the doyen of astronomers, Sir Arthur Eddington, both vigorously opposed the concepts involved in stellar collapse beyond the white dwarf stage. Thus the subject appears to have been put on hold coincident with the outbreak of war in 1939.
During the 1940's, virtually all capable physicists were occupied with tasks relating to the war effort. Apparently this was not so for Russian-born astronomer-physicist, George Gamow, a professor at Leningrad who had taken up a position at George Washington University in 1934. Gamow conceived the beginning of the Hubble expanding universe as a thermonuclear fireball in which the original stuff of creation was a dense gas of protons, neutrons, electrons, and gamma radiation which transmuted by a chain of nuclear reactions into the variety of elements that make up the world of today. Referring to this
work, Overbye4 writes: "In the forties, Gamow and a group of collaborators wrote a series of papers spelling out the details of thermonucleogenesis. Unfortunately their scheme didn't work. Some atomic nuclei were so unstable that they fell apart before they could fuse again into something heavier, thus breaking the element building chain. Gamow's team disbanded in the late 40's, its work ignored and disdained." Among this work was a paper by Gamow and Schoenfeld that proposed that energy loss from aging stars would be mediated by an efflux of neutrinos. This proposal appears to have been overlooked or ignored until the 1960's.
Conservation of energy law under fire
As time went by, the need for the neutrino grew, firstly to save the law of conservation of energy, but also laws of conservation of momentum, angular momentum (spin), and lepton number. As knowledge of what it ought to be like grew, plus the knowledge accruing from the intense efforts to produce the atom bomb, possible means of detecting this particle began to emerge. In 1953, experiments were begun by a team led by C.L. Cowan and F. Reines.' Fission reactors were now in existence in which the breakdown of uranium yielded free neutrons that, outside of the atomic nucleus, were unstable and broke down via beta decay to yield a proton, an electron, and, if it existed, the missing particle.
Detection of the elusive neutrino
The Cowan and Reines team devised an elaborate scheme to detect the antineutrinos from a reactor. By 1956 their system was detecting 70 such events per day, unequivocally ascribable to antineutrinos. It now remained to prove that this particle was not its own antiparticle, as is the case with the photon. This was done by R.R. Davis in 1956', using a detection system designed specifically for what the properties of the neutrino should be and testing it with an antineutrino source from a fission reactor.
Renewal of the search for the neutron star
The subject of the fate of imploding stars re- opened with vigor when both Robert Oppenheimer and John Wheeler, two of the really great names of physics, attended a conference in Brussels in 1958. Oppenheimer believed that his 1939 papers said all that needed to be said about such implosions. Wheeler disagreed, wanting to know what went on beyond the well-established laws of physics.
When Oppenheimer and Snyder did their work in 1939, it had been hopeless to compute the details of the implosion. In the meantime, nuclear weapons design had provided the necessary tools because, to design a bomb, nuclear reactions, pressure effects, shock waves, heat, radiation, and mass ejection had to be taken into account. Wheeler realized that his team had only to rewrite their computer programs so as to simulate implosion rather than explosion. However his hydrogen bomb team had been disbanded and it fell to Stirling Colgate at Livermore, in collaboration with Richard White and Michael May, to do these simulations. Wheeler learned of the results and was largely responsible for generating the enthusiasm to follow this line of research. The term 'black hole' was coined by Wheeler.
The theoretical basis for supernova explosions is said to have been laid by E. M. Burbidge, G.R. Burbidge, W. A. Fowler, and Fred Hoyle in a 1957 paper2. However, even in Hoyle and Narlikar's text book, "The Physics-Astronomy Frontier" (1980), no consideration is given to a role for neutrinos in the explosive conduction of energy away from the core of a supernova. In their 1957 paper, Hoyle and his co-workers proposed that when the temperature of an aging massive star rises to about 7 billion degrees K, iron is rapidly converted into helium by a nuclear process that absorbs energy. In meeting the sudden demand for this energy, the core cools rapidly and shrinks catastrophically, implodes in seconds, and the outer envelope crashes into it. As the lighter elements are heated by the implosion they burn so rapidly that the envelope is blasted into space. So, two years after the first publication of The Urantia Book, the most eminent authorities in the field of star evolution make no reference to the "vast quantities of tiny particles devoid of electric potential" that the book says escape from the star interior to bring about its collapse. Instead they invoke the conversion of iron to helium, an energy consuming process now thought not to be of significance.
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