For nearly half a century, Fred Hoyle has been involved in major, highly
controversial scientific issues, especially those concerned with the origin
and evolution of the Universe and of life. On the whole, the contemporary
scientific establishment tends to be dismissive of Hoyle’s cosmological
and biological theories, but many of his fundamental points still need to
be answered. Whatever the ultimate judgment on those may be, there is no
doubt that his work on the origin of the elements will stand as one of the
most significant contributions to science this century.

Hoyle writes as fluently and fearlessly as he speaks, and his description
of the chain of events that led to his belief that there must be a hitherto
unknown 7.65 megaelectronvolt energy level in the isotope carbon-12 is a
splendid example of how critical scientific discoveries can emerge through
the vicissitudes of a scientist’s life. The links in this case begin with
the American physicist Hans Bethe’s 1939 paper on the conversion of hydrogen
to helium as the source of the Sun’s energy. The other links came after
the war, with a student who abandoned a problem set by Hoyle, his consequent
frustration with the Cambridge doctoral system, and a chance meeting with
the astronomer Walter Baade at the 1952 Assembly of the International Astronomical
Union in Rome. This last led to an invitation to visit Mount Wilson and
lecture at Caltech in 1953.

It was during the preparation of these lectures that Hoyle became certain
that the production of carbon from helium in the process of nucleosynthesis
could not occur unless a 7.65 MeV energy level existed in carbon-12. The
first reaction of the American nuclear astrophysicist Willy Fowler was that
‘I had somehow gone a long way off my mental compass bearings’. But Hoyle
persuaded Fowler to design a new experiment and when he heard the result
‘the orange trees smelled even sweeter’.

They might well have done, because this result led directly to Hoyle’s
1954 paper on the synthesis of elements from carbon to nickel and to the
monumental 1957 paper, written in collaboration with Fowler and astrophysicists
Geoffrey and Margaret Burbidge, on the nucleosynthesis of the elements
in the interior of the stars.

During the war Hoyle worked in the Admiralty Signals Establishment where
he met the Austrian physicists Hermann Bondi and Tommy Gold. Their conversations
led to the birth of the continuous creation, steady state theory of the
Universe. Eventually, in 1948, their historic papers on the theory were
published. The paper that Bondi and Gold wrote stressed the philosophical
aspect of a perfect cosmological principle in which the Universe would have
a high degree of uniformity on the large scale both in time and space, thereby
avoiding the scientific problems associated with a beginning at a finite
past time. Hoyle’s paper, published two months after Bondi and Gold’s, developed
the mathematical theory of the scalar field, in which the continuous creation
of hydrogen would force a precise balance between the density of matter
in the Universe and the rate of expansion.

In describing the advantages of this theory during a series of BBC broadcasts
in 1950, Hoyle used the phrase ‘big bang’ in a derisory sense as a description
of the concept that the Universe had a beginning in a hot and dense state
at a finite past time. Ironically, Hoyle’s work on the nucleosynthesis of
the elements contained the seeds of destruction of the steady state theory
in its original form. The cosmic abundance of helium is about 27 per cent
and yet only between 2 and 3 per cent can be produced in the processes of
stellar nucleosynthesis. The authors of the steady state theory drew attention
to this problem in 1955, and then Hoyle and Roger Tayler reached the conclusion
that the major helium content of the Universe must have been produced in
a high-temperature phase.

This inevitably led to a partial return to Russian physicist George
Gamow’s theory of the hot initial phase of the Universe and the primordial
synthesis of helium. Coupled with the discovery of the cosmic microwave
background in 1965, the observational evidence appeared wholly in favour
of a big bang cosmology, and for fifteen years Hoyle’s interest in cosmology
waned. However, by 1985 the unproved assertions of certain cosmologists
again stimulated Hoyle’s interest and his recent publication of the modified
steady state concept, which features the creation of the Planck particles
(‘like a big bang in itself’) and their decay, may hold the seeds of a cosmology
in which the essential elements of the steady state and big bang cosmologies
are combined. At least, there must be increasing sympathy with Hoyle’s when
he says, ‘Big bang cosmology refers to an epoch that cannot be reached by
any form of astronomy, and, in more than two decades, it has not produced
a single successful prediction.’ As with the multitude of topics covered
in this book, Hoyle’s account of these developments deserves careful attention.

All who know Hoyle must realise that below the decisive and outspoken
public figure there lies a human being of great sensitivity. All who read
this book will know it, too. At one stage, referring to his early life,
Hoyle writes ‘but all this is rather petty stuff’. But for the reader it
soon becomes a matter of vital interest whether the boy takes a left and
two right turns after leaving home and reaches school, or takes the opposite
turnings and becomes a truant for the day. That, and his dispute at the
age of five with his teacher as to whether one of his wildflowers had five
or six petals, epitomises the honoured scientist who half a century later
resigned from the Plumian chair and the directorship of the Institute of
Theoretical Astronomy because he could no longer tolerate the Cambridge
mode of university politics.

Hoyle has had a major influence on the scientific thought of the second
half of the 20th century. Here is his compelling account of the successes
and tribulations of that life. It is compelling not only because of the
science, which often has to be dug out from intervening pages of many other
topics. It is these other topics that reveal Hoyle himself, whether in his
brilliant vignettes of his mentors or the often vivid descriptions of his
mountaineering exploits. Above all, some may feel that his father’s last
words to him, recounted in this book – ‘How long is the journey, lad’?
– is a question which Hoyle himself has not yet resolved.

Bernard Lovell was the first director of Jodrell Bank Experimental Station.

Robert Hanbury Brown, one of radar’s pioneers, is half way through this
account of his life’s work before he mentions the research that has made
him such a distinguished astronomer. In 1936, two weeks before his 20th
birthday, he arrived at Bawdsey Manor on the Suffolk coast. Watson Watt
had moved his group there, after the demonstrations at Orfordness had satisfied
Henry Tizard that the proposed radar chain around the coast would enable
the Royal Air Force to defeat the German bombers by day. Tizard believed
that they would then turn to night bombing, and it was to this problem of
defence against night bombers that Hanbury Brown was directed in the autumn
of 1937.

Few of the participants have written their story of the development
of radar in the Second World War so this account of the transformation of
Britain’s giant coastal defence radars to miniaturised systems for use in
the RAF night fighters and Coastal Command aircraft is an important historical
record. When war was declared, Hanbury Brown was at Northolt, Middlesex,
attempting to devise with the pilots of a night-fighter squadron a technique
for using the airborne radar for night interception. His account of these
efforts and of the demonstrations to civilian and service VIPs is often
amusing but it does not hide the hazards and immense scientific difficulties
of these early experiments.

The Luftwaffe turned to night bombing in the autumn of 1940 after their
defeat by day in the Battle of Britain. The radar-equipped RAF night fighters
had little success until the spring of 1941. In prewar tests Hanbury Brown
had discovered the reason: echoes from the ground limited the range of the
airborne radars to their operational altitude. It was the development of
the Ground Controlled Interception radar that, as Hanbury Brown so correctly
describes, led to the defeat of the German night-bombing campaign in the
spring of 1941.

His activities with the airborne radars were abruptly terminated early
in the same year when his oxygen supply failed at 20 000 feet. After months
in hospital, he returned to the Telecommunications Research Establishment
and worked on the development of radar beacons for use in combined RAF/Army
operations. At the end of 1942 he went to the US to assist with the further
development of beacons and identification systems for American forces operating
in Europe.

After postwar experiences in TRE and with the consultancy group of Watson-Watt,
Hanbury Brown decided to return to research. F. C. (Freddie) Williams, to
whom he appealed for advice, suggested that he might be more interested
in the work at Jodrell Bank than in computing. In September 1949, Jodrell
was then little more than a collection of ex-military radar trailers in
a sea of mud.

Hanbury Brown’s impact on the Jodrell group was immediate. He gives
an enthralling account of 90 nights of mammoth effort in the autumn of 1950
that led to the discovery of the radio emission from the spiral nebula in
Andromeda. It was then generally believed that radio waves received on Earth
originated within the Milky Way. This work and his investigations of other
localised radio sources injected him into the core of the conflict about
their nature.

Apart from the Andromeda nebula, none of the sources of radio emission
seemed to coincide with any object visible in the optical telescopes. If
they were star-like, then their angular sizes would be thousands of times
smaller than the limits of measurement possible at that epoch with conventional
phase stable radio interferometers. Separation of the interferometer aerials
by thousands of kilometres would be necessary and it was this that inspired
Hanbury Brown to develop the intensity interferometer. In tests at Jodrell
in 1952, he noticed with surprise that although radio records from the two
aerials fluctuated wildly they were, nevertheless, correlated. The realisation
that the interferometer worked through a turbulent medium led to epic arguments
about the extension of the principle to the optical domain. Here we have
a splendid account of the demonstration in a dark room at Jodrell that the
principle could be so extended and of the measurement of the angular diameter
of Sirius using two army searchlight mirrors as telescopes. While other
scientists argued and devised experiments to prove that the principle was
in defiance of quantum theory, Hanbury Brown made it work, and with Richard
Twiss, wrote the classic series of papers on the correlation of photons
in independent light beams.

These successes led to an engineered version of the interferometer,
and the search for clear skies led Hanbury Brown to Narrabri in the Australian
bush. The installation and operation of the two 22-foot diameter reflectors
in this remote district forms one of the seminal stories of 20th-century
science. So does its modern successor, now in operation at Culgoora built
on the principles of the original Michelson stellar interferometer and made
possible by electronic developments that were beyond contemplation when
Hanbury Brown first devised the means of escape from the limitations of
phase correlation.

Throughout his long career, Hanbury Brown has worked at the limits of
technological possibility in three domains – in radar, radio astronomy and
optical astronomy. He seems to have been happiest and most productive when
surmounting formidable obstacles and – in at least one case – the affair
of the correlation of photons, when working beyond the limits of conventional
theoretical wisdom. His experiences in breaking these barriers sometimes
seem fantastically improbable, but they add the common touch to a lucid
account of some of the major scientific and technical developments of this
century.

Bernard Lovell returned to the University of Manchester after the Second
World War, and began the researches at Jodrell Bank, which subsequently
became the Nuffield Radio Astronomy Laboratories. He retired as director
in 1981.

WE ENTER the last decade of the 20th century with the science of cosmology
in a most curious state. In some respects, it seems overburdened with complex
theories, but this complexity arises from two straightforward observations
made during the last quarter century. The discovery of the cosmic microwave
background radiation appeared to be a great clarification, leaving little
room for doubt that the Universe has evolved from a highly condensed state
10 to 20 billion years ago in the hot big bang. More recently, measurement
of the dynamical properties of clusters of galaxies has led to the strange
conclusion that the clusters must contain 10 times as much dark matter as
the aggregate mass observed in all the constituent galaxies, otherwise the
cluster would not be gravitationally bound and would disintegrate.

In The Stuff of the Universe we have an authoritative and exceptionally
clear account of the consequences for our understanding of the Universe.
The authors explore in some detail the possible nature of this dark matter.
The missing links needed to give the symmetries in the standard models of
the nuclear physicist seem to be prominent candidates, for example, the
axions which are more common but as elusive neutrinos. It is, indeed, a
cautionary thought for observational astronomers that particles comprising
90 per cent of the matter of the Universe have not been observed and may
not be observable.

The Universe is expanding and for more than half a century astronomers
have measured the red shifts of galaxies and more recently of quasars, in
an effort to discover whether the expansion will continue forever, or whether
the Universe will eventually collapse. If the theorists are correct this
search can be abandoned because the mass of the luminous and dark matter
gives a density lying somewhere between a tenth and 10 times of the critical
density corresponding to a flat universe model. As the Universe expands
any departure from the critical density will increase and so, the authors
conclude, the density must have been established precisely to within one
part in 10**15 of this critical value one second after the beginning of
the expansion. It seems that the Universe will expand until it eventually
comes to a halt and the regions of space are empty.

Of the many coincidences in the Universe that make life possible, the
authors believe that the greatest is that the Universe is flat and that
the amount of ordinary (baryonic) matter is so close (a ratio of one in
10) to that of the dark matter. Indeed, the account of the string of coincidences
and the delicacy of many parameters which make life possible is a fascinating
section in this book. In 1988 two distinguished American cos mologists assessed
a probability of only 0.01 that any contemporary cosmology could be correct.
Is the Universe made for us or do we inhabit the one possible amongst a
multiplicity of hostile co-existing universes? John Gribbin and Martin Rees
are wisely noncommittal. They leave us as they leave themselves – with a
sense of wonder.

*Published as Cosmic Coincidences by Bantam Books in the US, $9.95 pbk.

Sir Bernard Lovell was professor of radio astronomy at the University
of Manchester and director of the Nufield Radio Astronomy Laboratories Jodrell
Bank, until 1981