299
The Higgs boson destroys itself
within trillionths of a second of being
born. It is created when other particles
interact with the Higgs field.See also: Albert Einstein 214–21 ■ Erwin Schrödinger 226–33 ■ Georges Lemaître 242–45 ■ Paul Dirac 246–47 ■
Sheldon Glashow 292–93
FUNDAMENTAL BUILDING BLOCKS
fundamental importance because
it answered the question “why
are some force-carrying particles
massive while others are massless?”
Fields and bosons
Classical (pre-quantum) physics
imagines electrical or magnetic
fields as continuous, smoothly
changing entities spread through
space. Quantum mechanics rejects
the notion of a continuum, so fields
become distributions of discrete
“field particles” where the strength
of the field is the density of the field
particles. Particles passing through
a field are influenced by it via
exchange of “virtual” force-carrying
particles called gauge bosons.
The Higgs field fills space—
even a vacuum—and elementary
particles gain mass by interacting
with it. How this effect occurs can
be explained by analogy. Imagine
a field covered in thick snow that
skiers and people in snowshoes
must cross. Each person will take
more or less time, depending on
how strongly they “interact” with
the snow. Those that glide across
on skis are like low-mass particles,
while those that sink into the snow
experience a greater mass as they
travel. Massless particles, such as
photons and gluons—the force-
carriers of the electromagnetic and
strong nuclear forces respectively—
are unaffected by the Higgs field
and sail straight through, like geese
flying over the field.The hunt for the Higgs
In the 1960s, six physicists,
including Peter Higgs, François
Englert, and Robert Brout, developedthe theory of “spontaneous
symmetry breaking,” which
explained how the particles that
mediate the weak force, the W
and Z bosons, are massive, while
protons and gluons have no mass.
This symmetry breaking was
crucial in the formulation of the
electroweak theory (pp.292–93).
Higgs showed how the Higgs
boson (or rather the decay products
of the boson) should be detectable.
The search for the Higgs
boson spawned the world’s
largest science project, the Large
Hadron Collider—a giant proton
collider with a 17-mile (27-km)
circumference, buried 300 ft (100 m)
underground. When running full
tilt, the LHC generates energies
similar to those that existed just
after the Big Bang—enough to
create one Higgs boson every
billion collisions. The difficulty is
spotting its traces among a vast
shower of debris—and the Higgs
is so massive that, on appearing,
it decays instantly. However, after
nearly 50 years of waiting, the
Higgs has finally been confirmed. ■Peter Higgs Born in Newcastle-upon-Tyne,
England, in 1929, Peter Higgs
earned undergraduate and
doctoral degrees from King’s
College, London before joining
the University of Edinburgh as
a Senior Research Fellow. After a
stint in London, he returned to
Edinburgh in 1960. Walking in the
Cairngorm Mountains, Higgs had
his “one big idea”—a mechanism
that would enable a force field to
generate both high-mass and
low-mass gauge bosons. Others
were working along similar lines,
but we talk of the “Higgs field”
today, rather than the Brout–Englert–Higgs field, because his
1964 article described how the
particle could be spotted. Higgs
claims to have an “underlying
incompetence” since he did not
study particle physics at the PhD
level. This handicap did not stop
him from sharing the 2013 Nobel
Prize in Physics with François
Englert for their work in 1964.Key works1964 Broken Symmetry and the
Mass of Gauge Vector Mesons
1964 Broken Symmetries and the
Mass of Gauge Bosons