Fred Hoyle - Origin of Nucleosynthesis

Origin of Nucleosynthesis

In the 1950s, Hoyle was the leader of a group of very talented experimental and theoretical physicists; with William Alfred Fowler, Margaret Burbidge, and Geoffrey Burbidge. This group realized the basic ideas of how all the chemical elements in our Universe were manufactured, with this now being a field called nucleosynthesis. Famously, in 1957, this group produced the cornerstone B2FH paper (known for the initials of the four authors) in which the field of nucleosynthesis was defined and the large picture solved.

An early paper of Hoyle's made an interesting use of the anthropic principle. In trying to work out the routes of stellar nucleosynthesis, he observed that one particular nuclear reaction, the triple-alpha process, which generates carbon, would require the carbon nucleus to have a very specific resonance energy for it to work. The large amount of carbon in the universe, which makes it possible for carbon-based life-forms of any kind to exist, demonstrated that this nuclear reaction must work. Based on this notion, he made a prediction of the energy levels in the carbon nucleus that was later borne out by experiment.

These energy levels, while needed to produce carbon in large quantities, were statistically very unlikely. Hoyle later wrote:

Would you not say to yourself, "Some super-calculating intellect must have designed the properties of the carbon atom, otherwise the chance of my finding such an atom through the blind forces of nature would be utterly minuscule. A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as with chemistry and biology, and that there are no blind forces worth speaking about in nature. The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question." —Fred Hoyle

His co-worker William Alfred Fowler eventually won the Nobel Prize for Physics in 1983 (with Subrahmanyan Chandrasekhar), but for some reason Hoyle’s original contribution was overlooked, and many were surprised that such a notable astronomer missed out. Fowler himself in an autobiographical sketch affirmed Hoyle’s pioneering efforts:

The concept of nucleosynthesis in stars was first established by Hoyle in 1946. This provided a way to explain the existence of elements heavier than helium in the universe, basically by showing that critical elements such as carbon could be generated in stars and then incorporated in other stars and planets when that star "dies". The new stars formed now start off with these heavier elements and even heavier elements are formed from them. Hoyle theorized that other rarer elements could be explained by supernovas, the giant explosions which occasionally occur throughout the universe, whose temperatures and pressures would be required to create such elements. — William Fowler