Is the discovery of the Higgs particle what Joe Biden would describe as a big . . . deal?
Yes and no. It is a milestone, but not a breakthrough. It is the
culmination of an enormous international effort over many years.
However, the Higgs particle was predicted to exist by a theory that has
passed many precise tests, and so it would have been a shock had it
turned out not to exist. Therefore, unless the Higgs is
discovered to have unexpected properties, simply finding the Higgs will
not unlock any secrets.
What is the Higgs particle? It is an “elementary excitation” of the
“Higgs field.” (Yes, the word ‘excitation’ is used in physics, not just
in a Beach Boys song!) All of space is permeated by “fields.” They are
the basic stuff of nature: all the matter and forces in the world are
aspects of these fields. There are many kinds of them: electromagnetic
fields, gravitational fields, electron fields, neutrino fields, quark
fields, and so on. In our present theory, the Standard Model of particle
physics, there are 18 types of fields, though there are many reasons to
believe that others, as yet unknown, exist.
Fields give rise to forces. For instance, magnetic forces are due to
the magnetic fields. A compass needle tells you in what direction the
magnetic field in a particular place is pointing. Besides pushing on
things, fields can have waves in them. For instance, light waves, radio
waves, microwaves, etc. are all waves in the electromagnetic field. But
one of the mysterious things that quantum mechanics tells us is that the
waves in these fields can also be thought of as particles.
So the Higgs particle is the smallest amount (or “quantum”) that you can have of a wave in the Higgs field.
But there are 18 kinds of fields (and
particles) in our present theory, so what’s so special about the Higgs
field and the Higgs particle? First, Higgs particles were the only
particles in the Standard Model that hadn’t yet been produced in the
laboratory. Second, the Higgs field gives mass to many other types of
particle. Other fields vary a lot in strength from place to place —
magnetic fields are stronger close to a magnet than far away, for
instance. The gravitational field is stronger near the sun than near the
earth. But the Higgs field has an almost constant strength throughout
the universe — and that strength is huge compared to that of any other
known field almost anywhere in the known universe. Being immersed in
this strong Higgs field is what gives most other particles their masses.
One of the biggest unsolved problems in physics is why the Higgs
field has the strength it does. While it is certainly much stronger than
the other fields we know about, theoretically one would expect it to be vastly stronger still — indeed, about 1017 (=
100,000,000,000,000,000) times stronger than it is. Why? Because there
are certain known effects that would tend to make it that strong. So it
seems that there must be some other, as yet unknown effects
that almost exactly cancel the known effects to give the Higgs field the
strength we actually see. That seems incredibly bizarre to theorists.
For almost 40 years they have been wondering what those other effects
are. Finding out is the real goal of the Large Hadron Collider (LHC) and truly would be a huge breakthrough with enormous theoretical payoffs.
The main contender for those “other effects” is based on an idea
called “supersymmetry.” If it is right, then every known particle would
have a new kind of particle associated with it. For example, electrons
would be associated with much more massive particles called “scalar
electrons.” In effect, these new particles would cancel the effects on
the Higgs of the known particles. What most particle physicists are
hoping and expecting to see at the LHC is evidence for these new
particles — or some other new effect that explains why the Higgs field
has the strength it does.
What if no such new effect is seen? What if the only thing found at
the LHC is the Higgs particle? It would be a disaster for fundamental
physics. It would mean that the LHC was a flop.
One last thing: Why do journalists — not physicists — call
the Higgs particle “the God particle”? It is because Leon Lederman, a
Nobel-prize winning physicist, wrote a book in which he wanted to call
the Higgs particle the “god-damn particle,” because it was so hard to
find. Apparently his publishers thought “God particle” would sell
better. So, thanks to the idiocy of publishers, we have to suffer one of
the most inane pieces of media hype in history. Does the Higgs have
anything to do with how the universe began? No. Is it the holy grail of
physics? No. But its discovery is, for those of us interested in
particle physics, something to celebrate.
— Stephen M. Barr is a professor of theoretical particle physics at the University of Delaware and author of Modern Physics and Ancient Faith.
