Fred Hoyle

Sir Fred Hoyle was an English astronomer who formulated the theory of stellar nucleosynthesis and was one of the authors of the influential B²FH paper.
He held controversial views on some scientific matters — in particular, in his rejection of the "Big Bang" theory in favour of a "steady-state model", and his promotion of panspermia as the origin of life on Earth.
He spent most of his working life at St John's College, Cambridge, and served as the founding director of the Institute of Theoretical Astronomy at Cambridge.
Hoyle also wrote science fiction novels, short stories, and radio plays, co-created television serials, and co-authored twelve books with his son, Geoffrey Hoyle.

Biography

Early life

Hoyle was born near Bingley in Gilstead, West Riding of Yorkshire, England. His father Ben Hoyle was a violinist and worked in the wool trade in Bradford, and served as a machine gunner in the First World War. His mother, Mabel Pickard, had studied music at the Royal College of Music in London and later worked as a cinema pianist. Hoyle was educated at Bingley Grammar School and read mathematics at Emmanuel College, Cambridge. As a youth, he sang in the choir at the local Anglican church.
In 1936, Hoyle shared the Mayhew Prize with George Stanley Rushbrooke.

Career

In late 1940, Hoyle left Cambridge to go to Portsmouth to work for the Admiralty on radar research, for example devising a method to get the altitude of incoming aeroplanes. He was also put in charge of countermeasures against the radar-guided guns found on the Graf Spee after its scuttling in the River Plate. Britain's radar project was a large-scale operation, and was probably the inspiration for the large British project in Hoyle's novel The Black Cloud. Two colleagues in this war work were Hermann Bondi and Thomas Gold, and the three had many discussions on cosmology. The radar work involved several trips to North America, where he took the opportunity to visit astronomers. On one trip to the US, he learned about supernovae at Caltech and Mount Palomar and, in Canada, the nuclear physics of plutonium implosion and explosion, noticed some similarity between the two and started thinking about supernova nucleosynthesis. He had an intuition at the time "I will make a name for myself if this works out". He also formed a group at Cambridge exploring stellar nucleosynthesis in ordinary stars and was bothered by the paucity of stellar carbon production in existing models. He noticed that one existing process would be made a billion times more productive if the carbon-12 nucleus had a resonance at 7.7 MeV, but nuclear physicists at the time omitted such an observed value. On another trip, he visited the nuclear physics group at Caltech, spent a few months of sabbatical there and persuaded them against their scepticism to find the Hoyle state in carbon-12, from which a full theory of stellar nucleosynthesis was developed, co-authored by Hoyle and members of the Caltech group.
In 1945, after the war ended, Hoyle returned to Cambridge University as a lecturer at St John's College, Cambridge. Hoyle's Cambridge years, 1945–1973, saw him rise to the top of world astrophysics theory, on the basis of a startling originality of ideas covering a wide range of topics. In 1958, Hoyle was appointed Plumian Professor of Astronomy and Experimental Philosophy in Cambridge University. In 1967, he became the founding director of the Institute of Theoretical Astronomy, where his innovative leadership quickly led to this institution becoming one of the premier groups in the world for theoretical astrophysics. In 1971, he was invited to deliver the MacMillan Memorial Lecture to the Institution of Engineers and Shipbuilders in Scotland. He chose the subject "Astronomical Instruments and their Construction". Hoyle was knighted in the 1972 New Year Honours.
Although the occupant of two distinguished offices, by 1972 Hoyle had become unhappy with his life in Cambridge. A dispute over election to a professorial chair led to Hoyle resigning as Plumian professor in 1972. The following year he also resigned the directorship of the institute. Explaining his actions, he later wrote: "I do not see any sense in continuing to skirmish on a battlefield where I can never hope to win. The Cambridge system is effectively designed to prevent one ever establishing a directed policy - key decisions can be upset by ill-informed and politically motivated committees. To be effective in this system one must for ever be watching one's colleagues, almost like a Robespierre spy system. If one does so, then of course little time is left for any real science."
After leaving Cambridge, Hoyle wrote several popular science and science fiction books, as well as presenting lectures around the world, partly to provide a means of support. Hoyle was still a member of the joint policy committee, during the planning stage for the 150-inch Anglo-Australian Telescope at Siding Spring Observatory in New South Wales. He became chairman of the Anglo-Australian Telescope board in 1973, and presided at its inauguration in 1974 by Charles, Prince of Wales.

Decline and death

After his resignation from Cambridge in 1972, Hoyle moved to the Lake District and occupied his time with treks across the moors, writing books, visiting research centres around the world, and working on science ideas ; the topics he wrote about include "Stonehenge, panspermia, Darwinism, paleontology, and viruses from space". On 24 November 1997, while hiking across moorlands in west Yorkshire, near his childhood home in Gilstead, Hoyle fell into a steep ravine called Shipley Glen. He was located about 12 hours later by a party using search dogs. He was hospitalised for two months with a broken shoulder bone. In 2001, he suffered a series of strokes and died in Bournemouth on 20 August of that year.

Views and contributions

Origin of nucleosynthesis

Hoyle authored the first two research papers ever published on synthesis of chemical elements heavier than helium by stellar nuclear reactions. The first of these in 1946 showed that cores of stars will evolve to temperatures of billions of degrees, much hotter than temperatures considered for thermonuclear origin of stellar power in main-sequence stars. Hoyle showed that at such high temperatures the element iron can become much more abundant than other heavy elements owing to thermal equilibrium among nuclear particles, explaining the high natural abundance of iron. This idea would later be called the eProcess. Hoyle's second foundational nucleosynthesis publication, published in 1954, showed that the elements between carbon and iron cannot be synthesised by such equilibrium processes. He attributed those elements to specific nuclear fusion reactions between abundant constituents in concentric shells of evolved massive, pre-supernova stars. This startlingly modern picture is the accepted paradigm today for the supernova nucleosynthesis of these primary elements. In the mid-1950s, Hoyle became the leader of a group of talented experimental and theoretical physicists who met in Cambridge: William Alfred Fowler, Margaret Burbidge, and Geoffrey Burbidge. This group systematised basic ideas of how all the chemical elements in our universe were created, with this now being a field called nucleosynthesis. Famously, in 1957, this group produced the B²FH paper in which the field of nucleosynthesis was organised into complementary nuclear processes. They added much new material on the synthesis of heavy elements by neutron-capture reactions, the so-called s process and the r process. So influential did the B²FH paper become that for the remainder of the twentieth century it became the default citation of almost all researchers wishing to cite an accepted origin for nucleosynthesis theory, and as a result, the path-breaking Hoyle 1954 paper fell into obscurity. Historical research in the 21st century has brought Hoyle's 1954 paper back to scientific prominence. Those historical arguments were first presented to a gathering of nucleosynthesis experts attending a 2007 conference at Caltech organised after the deaths of both Fowler and Hoyle to celebrate the 50th anniversary of the publication of B²FH. Ironically the B²FH paper did not review Hoyle's 1954 supernova-shells attribution of the origin of elements between silicon and iron despite Hoyle's co-authorship of B²FH. Based on his many personal discussions with Hoyle Donald D. Clayton has attributed this seemingly inexplicable oversight in B²FH to the lack of proofreading by Hoyle of the draft composed at Caltech in 1956 by G. R. Burbidge and E. M. Burbidge.
The second of Hoyle's nucleosynthesis papers also introduced an interesting use of the anthropic principle, which was not then known by that name. In trying to work out the steps of stellar nucleosynthesis, Hoyle calculated that one particular nuclear reaction, the triple-alpha process, which generates carbon from helium, would require the carbon nucleus to have a very specific resonance energy and spin 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 to Hoyle that this nuclear reaction must work. Based on this notion, Hoyle therefore predicted the values of the energy, the nuclear spin and the parity of the compound state in the carbon nucleus formed by three alpha particles, which was later borne out by experiment.
This energy level, while needed to produce carbon in large quantities, was statistically very unlikely to fall where it does in the scheme of carbon energy levels. Hoyle later wrote:
His co-worker William Alfred Fowler eventually won the Nobel Prize for Physics in 1983, but Hoyle's original contribution was overlooked by the electors, and many were surprised that such a notable astronomer missed out. Fowler himself in an autobiographical sketch affirmed Hoyle's pioneering efforts: