ASPEN, Colo. — Last week, physicists around the world were glued to computers at very odd hours (I was at a 1 a.m. physics “party” here with a large projection screen and dozens of colleagues) to watch live as scientists at the Large Hadron Collider, outside Geneva, announced that they had apparently found one of the most important missing pieces of the jigsaw puzzle that is nature.
The “Higgs particle,”
proposed almost 50 years ago to allow for consistency between
theoretical predictions and experimental observations in elementary
particle physics, appears to have been discovered
— even as the detailed nature of the discovery allows room for even
more exotic revelations that may be just around the corner.
It is natural for those not deeply involved in the half-century quest
for the Higgs to ask why they should care about this seemingly esoteric
discovery. There are three reasons.
First, it caps one of the most remarkable intellectual adventures in
human history — one that anyone interested in the progress of knowledge
should at least be aware of.
Second, it makes even more remarkable the precarious accident that
allowed our existence to form from nothing — further proof that the
universe of our senses is just the tip of a vast, largely hidden cosmic
iceberg.
And finally, the effort to uncover this tiny particle represents the
very best of what the process of science can offer to modern
civilization.
If one is a theoretical physicist working on some idea late at night or
at a blackboard with colleagues over coffee one afternoon, it is almost
terrifying to imagine that something that you cook up in your mind might
actually be real. It’s like staring at a large jar and being asked to
guess the number of jelly beans inside; if you guess right, it seems too
good to be true.
The prediction of the Higgs particle accompanied a remarkable revolution
that completely changed our understanding of particle physics in the
latter part of the 20th century.
Just 50 years ago, in spite of the great advances of physics in the
previous half century, we understood only one of the four fundamental
forces of nature — electromagnetism — as a fully consistent quantum
theory. In just one subsequent decade, however, not only had three of
the four known forces succumbed to our investigations, but a new elegant
unity of nature had been uncovered.
It was found that all of the known forces could be described using a
single mathematical framework — and that two of the forces,
electromagnetism and the weak force (which governs the nuclear reactions
that power the sun), were actually different manifestations of a single
underlying theory.
How could two such different forces be related? After all, the photon,
the particle that conveys electromagnetism, has no mass, while the
particles that convey the weak force are very massive — almost 100 times
as heavy as the particles that make up atomic nuclei, a fact that
explains why the weak force is weak.
What the British physicist Peter Higgs and several others showed is that
if there exists an otherwise invisible background field permeating all
of space, then the particles that convey some force like
electromagnetism can interact with this field and effectively encounter
resistance to their motion and slow down, like a swimmer moving through
molasses.
As a result, these particles can behave as if they are heavy, as if they
have a mass. The physicist Steven Weinberg later applied this idea to a
model of the weak and electromagnetic forces previously proposed by
Sheldon L. Glashow, and everything fit together.
This idea can be extended to the rest of particles in nature, including
the protons and neutrons and electrons that make up the atoms in our
bodies. If some particle interacts more strongly with this background
field, it ends up acting heavier. If it interacts more weakly, it acts
lighter. If it doesn’t interact at all, like the photon, it remains
massless.
f anything sounds too good to be true, this is it. The miracle of mass —
indeed of our very existence, because if not for the Higgs, there would
be no stars, no planets and no people — is possible because of some
otherwise hidden background field whose only purpose seems to be to
allow the world to look the way it does.
Dr. Glashow, who along with Dr. Weinberg won a Nobel Prize
in Physics, later once referred to this “Higgs field” as the “toilet”
of modern physics because that’s where all the ugly details that allow
the marvelous beauty of the physical world are hidden.
But relying on invisible miracles is the stuff of religion, not science.
To ascertain whether this remarkable accident was real, physicists
relied on another facet of the quantum world.
Associated with every background field is a particle, and if you pick a
point in space and hit it hard enough, you may whack out real particles.
The trick is hitting it hard enough over a small enough volume.
And that’s the rub. After 50 years of trying, including a failed attempt
in this country to build an accelerator to test these ideas, no sign of
the Higgs had appeared. In fact, I was betting against it, since a
career in theoretical physics has taught me that nature usually has a
far richer imagination than we do.
Until last week.
Every second at the Large Hadron Collider, enough data is generated to
fill more than 1,000 one-terabyte hard drives — more than the
information in all the world’s libraries. The logistics of filtering and
analyzing the data to find the Higgs particle peeking out under a
mountain of noise, not to mention running the most complex machine
humans have ever built, is itself a triumph of technology and
computational wizardry of unprecedented magnitude.
The physicist Victor F. Weisskopf — the colorful director in the early 1960s of CERN,
the European Organization for Nuclear Research, which operates the
collider — once described large particle accelerators as the gothic
cathedrals of our time. Like those beautiful remnants of antiquity,
accelerators require the cutting edge of technology, they take decades
or more to build, and they require the concerted efforts of thousands of
craftsmen and women. At CERN, each of the mammoth detectors used to
study collisions requires the work of thousands of physicists, from
scores of countries, speaking several dozen languages.
Most significantly perhaps, cathedrals and colliders are both works of
incomparable grandeur that celebrate the beauty of being alive.
The apparent discovery of the Higgs may not result in a better toaster
or a faster car. But it provides a remarkable celebration of the human
mind’s capacity to uncover nature’s secrets, and of the technology we
have built to control them. Hidden in what seems like empty space —
indeed, like nothing, which is getting more interesting all the time —
are the very elements that allow for our existence.
By demonstrating that, last week’s discovery will change our view of
ourselves and our place in the universe. Surely that is the hallmark of
great music, great literature, great art ...and great science.
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