Topics

Bookshelf

17 August 2000

Antimatter – the Ultimate Mirror by Gordon Fraser, Cambridge University Press,
0 521 65252 9, £16.95/$24.95.

The correct prediction of antimatter by Paul Dirac is
arguably the most astonishing intellectual achievement of the 20th century. By insisting that
quantum theory and special relativity must be consistent, he was able to deduce the
generalization of the Schrödinger equation to the Dirac equation. By doing that he was able
to give a proximate explanation for spin, and to predict a whole new set of particles,
antimatter. That the human mind can discover a previously unknown part of the world is a
great achievement. (I largely agree with Antonino Zichichi who argued for Dirac as the
most important physicist of the 20th century in Physics World in March.) Gordon
Fraser’s lively and interesting book provides a broad treatment of this story, and the
history, science and implications of antimatter.

This is a very nice book, totally
accessible to any curious reader, yet with occasional thought-provoking pieces even for
experts. Fraser keeps a fast pace, explaining the science well but taking care not to dwell
too long on any difficult aspect. In a few places I didn’t fully agree with his viewpoint or
arguments. I will mention some of these as a service to possible readers, but they do not
detract from the value of a successful book.

Publishers are notorious for writing
anything they please on book jackets and in publicity. Fraser is not responsible for the
remark on the jacket that the book is about how science fiction became fact, which is, of
course, the opposite of what happened (the remark is taken from the title of chapter 1, but
its meaning is different there), or the charming reference to “Hans van der Meer” in the
publicity, mixing up Hans Dehmelt (whose work with traps is described in chapter 11) and
Simon van der Meer (who figured out how to get antiprotons in sufficient quantities to
make a collider.)

Chapter 1 describes the public excitement about the 1995 discovery
of antiatoms, and then begins the history. My impression of one bit of the history differs a
little here. Fraser says that at first Dirac thought that the antielectron was the proton. He
may be correct, but I have heard over the years that people pushed rather hard on Dirac
about where the predicted antielectron was – after all, predicting new particles was not
normal then. Dirac defensively remarked that perhaps it was the proton, though he knew
that that didn’t make sense.

The next chapter introduces the relevant symmetries,
charge conjugation, parity and time reversal, and then provides a quick history from Galileo
through Newton to Einstein. It includes the Thornhill portrait of Newton without a wig,
which I have seen in the Master’s Lodge of Trinity College, Cambridge – Newton looks
much more like a physicist there than in his usual wigged appearances. Here and later the
book has a nice way of giving brief descriptions that capture the essence of
people.

Chapter 3 is a history of the acceptance of atoms, and the discoveries of the
electron, nucleus, proton and neutron. Next is a more thorough biographical treatment of
Dirac, with some of the many anecdotes, followed by the development of quantum theory
and the Dirac equation. Chapter 5 describes the positron discovery, including the opposition
of R A Millikan. That opposition helped to make European physicists more aware that Carl
Anderson’s CalTech data could be the antielectron than were the US physicists. There is
also a (delightful for a theorist) quote from Rutherford of a sentiment that we still
encounter: “It seems to be to a certain degree regrettable that we had a theory of the
positive electron before the experiments…I would be more pleased if the theory had
appeared after the establishment of the experimental facts.”

Fraser then presents a
quick discussion of infinities, renormalization and Richard Feynman, and interesting
speculations on Dirac and Feynman’s distinctive personalities and the strong influences of
their fathers as they were growing up. The story moves to the development of accelerators
and the discovery of the antiproton, and then to quarks. (A minor point: the wording of a
sentence on p108 suggests that quarks have a known size, but in fact there is only an upper
limit and quarks are expected to be far too small to measure their size directly.) Next comes
further discussion of parity violation and then CP violation, leading up to Andrei
Sakharov’s statement of the conditions required for an explanation of the mysterious
baryon asymmetry of the universe.

Particle colliders, which of course, require
expertise in handling antimatter, are brought in and some of their discoveries presented.
The only typographic error I found was on p175, where the ratio of the top quark mass to
the b-quark mass is about 35, not 300. Chapter 13 is basically on antimatter technology,
including PET scans and more. Fraser gets somewhat sensational here, beginning the
chapter with a survey of the Reagan era “Star Wars” antimissile programme, and then
unfairly relating that to the US plans to build the Superconducting SuperCollider, even
seeing a connection to antimatter propulsion proposals and personnel for Star Wars. He
also laments the loss of the LEAR antiproton beam at CERN, and perhaps misses an
opportunity to discuss the difficulties of doing all science projects in times of limited
resources, and of deciding which ones to pursue.

Why the universe is matter and not
antimatter is still a mystery. The explanation of the evidence in chapter 14 is very clear.
However, there are more approaches that could eventually explain this mystery than the
book suggests. The problem is that the calculations are very difficult and the underlying
theory is not established. Perhaps most fundamentally, we do not yet know the origin and
size of the CP-violating effects that are essential to explain the matter asymmetry. One
piece of progress is that we do know now that the Standard Model cannot explain the
matter asymmetry of the universe, so new physics must enter. It is likely that the phases
that lead to the CP violation needed to generate the matter asymmetry arise when string
theories are compactified to three space dimensions and when supersymmetry is broken,
but these subjects are not yet well understood. If you think these approaches are somewhat
far out, you’ll enjoy Fraser’s speculations on this issue even more.
Gordon Kane,
Michigan.

Rutherford – Scientist Supreme by John Campbell, AAS publications, 494pp hbk
£25/$40 (obtainable direct from the publisher: AAS publications, PO Box 31-035,
Christchurch, New Zealand; e-mail “aas@its.canterbury.ac.nz”).

Ernest Rutherford
towered over the early 20th-century decryption of the atom. At a series of university
settings – Cambridge, McGill, Manchester and then Cambridge again – he masterminded a
progression of classic experiments that dramatically revealed the nature of radioactivity, and
the structure of the atom and its nucleus. Many of those he had chosen to be his research
partners – Blackett, Chadwick, Cockcroft, Geiger and Walton, among others – went on to
become physics figureheads in their own right. In Manchester, Rutherford inspired Niels
Bohr to abandon the theory of electrons in metals and turn to that of electrons in atoms
instead.

Rutherford biographies are not scarce, with inspired memoirs and nostalgic
reminiscences by several contemporaries – Allibone, Da Costa Andrade, Oliphant – and the
1983 biography Rutherford, Simple Genius by David Wilson.

The title of
Wilson’s book succinctly catches the nature of Rutherford. He was no fiery intellect like
many of his central European contemporaries. Instead, his slow but penetrating insight and
analysis, and his gift for patient, incisive investigation, isolated key problems and elucidated
them.

Rutherford was born in modest surroundings in New Zealand when the
country was still being settled. When New Zealand schoolchildren of the late 19th century
learned history, they learned British history – there was no New Zealand history. University
examination papers were despatched by boat to Britain for marking.

New Zealander
John Campbell – he teaches physics at the University of Canterbury – was struck, ashamed
even, by the lack of recognition of his nation’s premier scientist and he set out to do
something about it. He developed a fitting memorial at Rutherford’s birthplace in Nelson
and embarked on this major biography, which fleshed out Rutherford’s New Zealand
background. While other epochs in Rutherford’s life have been well documented, his youth
in New Zealand has until now been largely overlooked. Compared with 50 sketchy pages
in Wilson’s book, perhaps half of Campbell’s book deals with local matters – Rutherford’s
birth, schooling, early university education and periodic visits throughout his life. During his
studies, Rutherford emerged as a gifted student but no precocious childhood
genius.

As well as the focus on New Zealand, there is much valuable additional
material in the book – anecdotes, the paradox of how the 20th century’s foremost
experimental physicist never received the Nobel Prize for Physics (even before his historic
discovery of the atomic nucleus in 1911, he received the Nobel Prize for Chemistry for his
work on radioactivity), several major discoveries that were missed at Cambridge in the
early 1930s – the positron, induced radioactivity – and finally the bizarre circumstances of
his death at the age of only 66. (Details of Rutherford’s death are strangely absent in
existing biographies, written when many people still had an upright Victorian attitude.)
Rutherford had been influential in key applied research positions in the First World War.
What impact would his blustering no-nonsense personality have made in Second World
War science and technology?

The book underlines Rutherford’s continual push for
higher-energy particles. In a 1927 speech to the Royal Society, he said: “It has long been
my ambition to have available for study a copious supply of atoms and electrons which
have an individual energy far transcending that of particles from radioactive bodies.” At
Cambridge, industrial techniques were exploited in the search for higher voltages – an early
example of technology transfer. This ultimately led to Cockcroft and Walton’s accelerator,
carried further by Oliphant. However, Rutherford dropped the ball by not acknowledging
the arrival of the upstart cyclotron, developed by Ernest Lawrence in the
US.

Especially poignant is the description of Rutherford’s undemonstrative romance
and marriage to the faithful Mary (“May”) Newton, whom he met while a student in New
Zealand and who eventually followed him to Britain after patiently waiting to be
summoned.

Campbell’s homely but complete biography of “Ern” is totally in keeping
with Rutherford’s own bluntness – a valuable addition to the biography of a key scientific
figure. It will be particularly appreciated in New Zealand, even if major world publishers did
not agree with this antipodean focus. A shorter 250-page version is thus in the
pipeline.
Gordon Fraser, CERN.

Painstaking research

In his
Rutherford biography, New Zealand physicist John Campbell has done an immense amount
of spadework. Some of this is references in the book, but more complete references are
being assigned to public repositories. He says:

“I have filled 10 quarto 120-page
record books and three filing cabinet drawers with such notes. These have been willed to
the Rutherford Collection at the Alexander Turnbull Library, the historic arm of the
National Library of New Zealand. The master manuscript refers to these notes. The
biography also draws extensively on the local newspapers of the day, Rutherford family
correspondence and the official and unofficial records of the relevant
organizations.

“In such a major research, sometimes every paragraph, sentence or
even phrase requires a reference or further comment. This is too detailed for most users. In
this book only the main points will be referenced due to space considerations.

“A
master copy, which includes material edited out of the printed version, will be hand
annotated with full references and comments on the sources of every statement. Two years
after publication date, thus allowing for the incorporation of any new information which
may come to light as a result of the book, I will donate a copy of this master manuscript to
public repositories in each country with a Rutherford association. This will make the details
more freely accessible to interested people.

“There will be one condition imposed,
that for 10 years after the deposition date any person can copy no more than 10 pages per
day. After that period copying will be as per the usual custom for the particular archive.
During that 10 year period I will invite people seriously interested in Rutherford to
purchase their own copy from AAS Publications, PO Box 31-035, Christchurch, New
Zealand. Purchasers will be encouraged to donate their copy to any other appropriate
public repository.”
Repositories of Master Copies:
Alexander Turnbull
Library of the National Library of New Zealand
Nelson Provincial
Museum
Cambridge University Library (Manuscripts)
National Library of
Scotland
Center for the History of Science, Royal Swedish Academy of Sciences,
Stockholm
Musée Curie (France)
McGill University Library (Archives)
P L
Kapitza Institute for Physical Problems (Moscow)
American Institute of Physics,
Niels Bohr Library
National Library of Australia

bright-rec iop pub iop-science physcis connect