By Lawrence M. Krause, The New York Times, July 9, 2012
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| A computer-generated image shows a typical proton collision of the kind that produced evidence of a particle thought to be the Higgs boson. |
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.
Podcast: Science Times
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.
If 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 Center 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.
Lawrence
M. Krauss, the director of the Origins Project at Arizona State University, is
the author, most recently, of “A Universe From Nothing.”
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