Download 16 Sep 2012

Art Hobson, ahobson@uark.edu
NWA Times, 16 September 2012
A portrait of the Higgs boson
Science has had a sensational summer. In July, physicists at Europe's highenergy physics lab, CERN, discovered the predicted Higgs boson. In an
astonishing display last month, NASA landed a highly inquisitive robot on Mars.
"The Higgs" is central to the Standard Model of quantum physics, a boring
title for the most accurate and wide-ranging scientific theory ever.
According to this "theory of almost everything," the universe is made entirely
of a few types of fundamental "fields." The magnetic field, for example, is
familiar from toy magnets. This field exists in and around every magnet, anywhere
the magnet can affect other objects. The field is actually a condition of the space
in and around the magnet.
You've also experienced the gravitational field that causes things to fall and
holds you onto our planet. There are several other types of fields, most of which
you've never heard. Everything, including you, is actually made of these
fields. Fields are all there is.
Quantum physics, discovered last century, tells us these fields are
"quantized." This means that every field comes in indivisible bundles or packets,
called "quanta" (the plural of "quantum"), with each quantum carrying a certain
amount of energy (energy just means the ability to do things--to lift or move things
around). The microscopic "particles"--electrons, atoms, etc.-- are really just these
extended bundles of field energy.
The Standard Model is a mathematical theory of how all these fields (except
for gravity, which is not yet included in this theory) work together to explain the
particles and phenomena seen around us and in labs such as CERN.
Quanta come in two distinct types: those having "mass" and those having no
mass. When we say an object has mass, we mean it has "heaviness," or
"weight." Quanta having mass, such as electrons, protons, and atoms, are
classified as "matter." One property of matter is that it always moves slower than
light. But light itself is made of electric and magnetic fields, and the quanta of
these fields, known as "photons" ("pieces of light"), have no mass and always
move at lightspeed.
A fundamental theory should explain why there are these two types of
quanta. British physicist Peter Higgs figured this out in 1964. He hypothesized
(made an educated guess) a new type of quantized field that interacts with other
fields in such a way as to give them "heaviness," or mass. This "Higgs field" acts
on electrons and protons and other material particles much as molasses acts on a
stone dropped into a molasses jar: it slows them down, giving them "inertia"
("slowness"). Fields such as electric and magnetic fields, that do not interact with
the Higgs field, move at lightspeed.
Every quantum field has its own "quantum"--its own bundle of energy--that
characterizes that field. For the Higgs field, this quantum is called--you guessed it-the Higgs boson!
So in discovering the Higgs boson physicists discovered the signature of the
Higgs field, and the fundamental explanation of mass. This field extends
throughout the universe. Quanta that interact strongly with it have a large mass,
those that interact weakly have a small mass, and those that don't interact have no
mass and move at lightspeed. If the Higgs had turned out (as was possible) not to
exist, fundamental physics would have been turned into a messy can of
worms. This would have been interesting, but embarrassing for physics.
The Higgs was the only Standard Model field remaining to be
discovered. Having bagged the Higgs, physicists can now speculate with greater
confidence on such further possibilities as these:
The mysterious "dark matter" comprising 23 percent of the universe is made
of unknown material. The Standard Model suggests certain "supersymmetric"
quantum fields that might constitute this dark matter.
The even more mysterious "dark energy," comprising 73 percent of the
universe, might be made of the Higgs or similar fields. This dark energy seems to
exert a kind "negative gravity" that pushes the universe apart. Notice that 96
percent of the universe is made of unknown stuff--dark matter and dark
energy. The other 4 percent is the ordinary matter and radiation (light) seen around
us and described by the Standard Model. There's a lot remaining to be explained!
A field similar to the Higgs might have caused the fantastic "spreading" or
acceleration of space, time, and energy that occurred during the earliest trillionth of
a trillionth of a second. We might be closing in on the big bang.