αβγ, Hoyle, and the history of nucleosynthesis

Turner replies: The history of ideas is rarely just about equations and error bars; people and their interactions are equally important. Additional perspectives add to the picture, and I thank my colleagues for taking time to write. I add this to their insights.

In recounting the standard lore that the steady-state theory motivated the seminal 1957 paper by Geoffrey Burbidge, Margaret Burbidge, William Fowler, and Fred Hoyle (BBFH), which I learned from Helge Kragh’s Cosmology and Controversy (Princeton University Press, 1999), I did not mean to imply that Hoyle came to nucleosynthesis through cosmology. The origin of the elements was the problem du jour in the 1940s, and many of the leading nuclear and astrotheorists worked on it, including Hoyle. However, BBFH has 995 citations versus 91 for his 1946 paper for a reason: The theory is laid out in full detail in BBFH, while Hoyle’s initial foray covers one small aspect of it.

There is no doubt that nucleosynthesis motivated George Gamow’s thinking about cosmology; however, a similar case is hard to make for the steady state. A re-read of the papers in David Arnett and George Wallerstein’s reference 5 shows that the driving ideas are the perfect cosmological principle and continuous creation of matter, with no mention of the problem of the origin of the elements (or Hoyle’s 1946 paper).

I regret not having the space to discuss the missed opportunity for Ralph Alpher and Robert Herman to benefit from the insightful criticism they received and to get Big Bang nucleosynthesis right. In their last paper on the subject, they set up the correct equations for the neutron abundance and were one step away from predicting the large amount of helium-4 produced in the Big Bang, but they didn’t; ¹ they stuck with their neutron-capture model to the end.

Finally, other than the fact that the steady state helped to stir early interest in cosmology, I find little to connect it with precision cosmology. True, it is a strong theory in the sense of Karl Popper—it is easy to falsify. For that reason it was falsified quickly, and interest in cosmology died down again until the discovery of the cosmic microwave background.