Higgs: The Invention and Discovery of the 'God Particle'

287 Pages·2012·1.92 MB·English

by  Jim Baggott

HIGGS
HIGGS
The Invention and Discovery of the ‘God Particle’
JIM BAGGOTT
Great Clarendon Street, Oxford, OX2 6DP,
United Kingdom Oxford University Press is a department of the University of
Oxford.
It furthers the University’s objective of excellence in research, scholarship,
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Oxford University Press in the UK and in certain other countries © Jim Baggott
2012
The moral rights of the author have been asserted First Edition published in 2012
Impression: 1
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For Ange
CONTENTS
About the Author
Preface
Foreword by Steven Weinberg
Prologue: Form and Substance
Part I: Invention
1 The Poetry of Logical Ideas
In which German mathematician Emmy Noether discovers the relationship
between conservation laws and the deep symmetries of nature 2 Not a
Sufficient Excuse
In which Chen Ning Yang and Robert Mills try to develop a quantum field
theory of the strong nuclear force and annoy Wolfgang Pauli 3 People Will
Be Very Stupid About It
In which Murray Gell-Mann discovers strangeness and the ‘Eightfold Way’,
Sheldon Glashow applies Yang–Mills field theory to the weak nuclear force,
and people are very stupid about it 4 Applying the Right Ideas to the Wrong
Problem
In which Murray Gell-Mann and George Zweig invent quarks and Steven
Weinberg and Abdus Salam use the Higgs mechanism to give mass to the W
and Z particles (finally!) 5 I Can Do That
In which Gerard ’t Hooft proves that Yang–Mills field theories can be
renormalized and Murray Gell-Mann and Harald Fritzsch develop a theory of
the strong force based on quark colour Part II: Discovery
6 Alternating Neutral Currents
In which protons and neutrons are shown to have an internal structure and
the predicted neutral currents of the weak nuclear force are found, and then
lost, and then found again 7 They Must Be Ws
In which quantum chromodynamics is formulated, the charmquark is
discovered, and the W and Z particles are found, precisely where they were
predicted to be 8 Throw Deep
In which Ronald Reagan throws his weight behind the Superconducting
Supercollider, but when the project is cancelled by Congress six years later
all that remains is a hole in Texas 9 A Fantastic Moment
In which the Higgs boson is explained in terms that a British politician can
understand, hints of the Higgs are found at CERN, the Large Hadron
Collider is switched on, and then blows up 10 The Shakespeare Question
In which the LHC performs better than anyone expected (except Lyn Evans),
a year’s data is gathered in a few months and the Higgs boson runs out of
places to hide Epilogue: The Construction of Mass
Endnotes
Glossary
Bibliography
Index
ABOUT THE AUTHOR
Jim Baggott is an award-winning science writer. A former academic scientist, he
now works as an independent business consultant but maintains a broad interest
in science, philosophy, and history, and continues to write on these subjects in
his spare time. His previous books have been widely acclaimed and include: The
Quantum Story: A History in 40 Moments (Oxford University Press, 2011);
Atomic: The First War of Physics and the Secret History of the Atom Bomb
1939–49 (Icon Books, 2009), shortlisted for the Duke of Westminster Medal for
Military Literature, 2010; A Beginner’s Guide to Reality (Penguin, 2005);
Beyond Measure: Modern Physics, Philosophy and the Meaning of Quantum
Theory (Oxford University Press, 2004); Perfect Symmetry: The Accidental
Discovery of Buckminsterfullerene (Oxford University Press, 1994); and The
Meaning of Quantum Theory: A Guide for Students of Chemistry and Physics
(Oxford University Press, 1992).
PREFACE
The news that something very much like the Higgs boson had been discovered,
at CERN in Geneva on 4 July 2012, flashed instantaneously around the world
like some highly contagious electronic virus. Headlines screamed of this latest
triumph of high-energy physics. The discovery made front-page news, was
featured in many evening news bulletins, and reached an audience of billions.
Signals consistent with a particle that had first been hypothesized or ‘invented’
in 1964 had at last been found, 48 years later, at a cost of many billions of
dollars.
So, what was all the fuss about? What is the Higgs boson and why does it
matter so much? If this new particle really is the Higgs, what does it tell us about
the material world and the evolution of the early universe? Was finding it really
worth all the effort?
The answers to these questions can be found in the story of the so-called
Standard Model of particle physics. As the name implies, this is the framework
that physicists use to interpret the elementary constituents of all matter and the
forces that bind matter together, or cause it to fall apart. It is a body of work built
up over many decades of unstinting effort, which represents the physicists’ best
efforts to interpret the physical world around us.
The Standard Model is not yet a ‘theory of everything’. It does not account
for the force of gravity. In recent years you may have read about exotic new
theories of physics which attempt to unify the fundamental forces, including
gravity. These are theories such as supersymmetry and superstrings. Despite the
efforts of hundreds of theorists engaged on these projects, these new theories
remain speculative and have little or no supporting evidence from experiment.
For the time being, and despite flaws that have been acknowledged since its
inception in the late 1970s, the Standard Model is still where most of the real
action is.
The Higgs boson is important in the Standard Model because it implies the
existence of a Higgs field, an otherwise invisible field of energy which pervades
the entire universe. Without the Higgs field, the elementary particles that make
up you, me, and the visible universe would have no mass. Without the Higgs
field mass could not be constructed and nothing could be.
It seems we owe quite a lot to the existence of this field. This is one of the
reasons why the Higgs boson, the particle of the Higgs field, has been hyped in
the popular press as the God particle. This is a name heartily despised by
practising scientists, as it overstates the importance of the particle and draws
attention to the sometimes uneasy relationship between physics and theology. It
is, however, a name much beloved by science journalists and popular science
writers.
Many of the predicted consequences of the Higgs field were borne out in
particle collider experiments in the early 1980s. But inferring the field is not the
same as detecting its tell-tale field particle. It is therefore immensely reassuring
to know that the field is very probably here, there, and everywhere. The
possibility that the Higgs boson might not have been found was very real, and
the implications for the Standard Model were potentially devastating.
I began writing this book in June 2010, two years before the discovery was
made. I had just completed the manuscript of another book, called The Quantum
Story: A History in 40 Moments which, as the title implies, is a history of
quantum physics from 1900 to the present day. That book covered the
development of the Standard Model and the invention of the Higgs field and its
particle. A few months earlier CERN’s Large Hadron Collider reached record
proton–proton collision energies of seven trillion electron volts, and I figured
that a discovery might be possible within the next few years. Happily, I was
proved right.
The Quantum Story was published in February 2011. The present book is
based, in part, on that earlier work.
My thanks go to Latha Menon and the delegates at Oxford University Press,
who were ready to risk commissioning a book about a particle that hadn’t yet
been discovered. I have followed developments at CERN through the official
channels, but acknowledge a debt to a number of high-energy physics bloggers,
including Philip Gibbs, Tommaso Dorigo, Peter Woit, Adam Falkowski, Matt
Strassler and Jon Butterworth. Thanks also to Jon Butterworth, Sophie Tesauri,
James Gillies, Laurette Ponce, and Lyndon Evans for taking the time to talk to
me and share their growing sense of excitement. I would also like to express my
gratitude to Professors David Miller, and Peter Woit, who read and commented
on the draft manuscript, and to Professor Steven Weinberg, who also read
through the draft manuscript and kindly contributed a personal perspective in his
Foreword. Be assured that the errors that remain are all my own work.
Jim Baggott
Reading, 6 July 2012.