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Nearly a half-century ago, Peter Higgs and a
handful of other physicists were trying to understand
the origin of a basic physical feature: mass. You can
think of mass as an object’s heft or, a little more
5 precisely, as the resistance it offers to having its
motion changed. Push on a freight train (or a
feather) to increase its speed, and the resistance you
feel reflects its mass. At a microscopic level, the
freight train’s mass comes from its constituent
10 molecules and atoms, which are themselves built
from fundamental particles, electrons and quarks.
But where do the masses of these and other
fundamental particles come from?
When physicists in the 1960s modeled the
15 behavior of these particles using equations rooted in
quantum physics, they encountered a puzzle. If they
imagined that the particles were all massless, then
each term in the equations clicked into a perfectly
symmetric pattern, like the tips of a perfect
20 snowflake. And this symmetry was not just
mathematically elegant. It explained patterns evident
in the experimental data. But—and here’s the
puzzle—physicists knew that the particles did have
mass, and when they modified the equations to
25 account for this fact, the mathematical harmony was
spoiled. The equations became complex and
unwieldy and, worse still, inconsistent.
What to do? Here’s the idea put forward by Higgs.
Don’t shove the particles’ masses down the throat of
30 the beautiful equations. Instead, keep the equations
pristine and symmetric, but consider them operating
within a peculiar environment. Imagine that all of
space is uniformly filled with an invisible
substance—now called the Higgs field—that exerts a
35 drag force on particles when they accelerate through
it. Push on a fundamental particle in an effort to
increase its speed and, according to Higgs, you would
feel this drag force as a resistance. Justifiably, you
would interpret the resistance as the particle’s mass.
40 For a mental toehold, think of a ping-pong ball
submerged in water. When you push on the
ping-pong ball, it will feel much more massive than it
does outside of water. Its interaction with the watery
environment has the effect of endowing it with mass.
45 So with particles submerged in the Higgs field.
In 1964, Higgs submitted a paper to a prominent
physics journal in which he formulated this idea
mathematically. The paper was rejected. Not because
it contained a technical error, but because the
50 premise of an invisible something permeating space,
interacting with particles to provide their mass, well,
it all just seemed like heaps of overwrought
speculation. The editors of the journal deemed it “of
no obvious relevance to physics.”
55 But Higgs persevered (and his revised paper
appeared later that year in another journal), and
physicists who took the time to study the proposal
gradually realized that his idea was a stroke of genius,
one that allowed them to have their cake and eat it
60 too. In Higgs’s scheme, the fundamental equations
can retain their pristine form because the dirty work
of providing the particles’ masses is relegated to the
environment.
While I wasn’t around to witness the initial
65 rejection of Higgs’s proposal in 1964 (well, I was
around, but only barely), I can attest that by the
mid-1980s, the assessment had changed. The physics
community had, for the most part, fully bought into
the idea that there was a Higgs field permeating
70 space. In fact, in a graduate course I took that
covered what’s known as the Standard Model of
Particle Physics (the quantum equations physicists
have assembled to describe the particles of matter
and the dominant forces by which they influence
75 each other), the professor presented the Higgs field
with such certainty that for a long while I had no idea
it had yet to be established experimentally.
On occasion, that happens in physics. Mathematical
equations can sometimes tell such a convincing tale,
80 they can seemingly radiate reality so strongly, that
they become entrenched in the vernacular of
working physicists, even before there’s data to
confirm them.
Questions 42-52 are based on the following passage and supplementary material.
This passage is adapted from Brian Greene, “How the Higgs Boson Was Found.” ©2013 by Smithsonian Institution. The Higgs boson is an elementary particle associated with the Higgs field. Experiments conducted in 2012–2013 tentatively confirmed the existence of the Higgs boson and thus of the Higgs field.Nearly a half-century ago, Peter Higgs and a
handful of other physicists were trying to understand
the origin of a basic physical feature: mass. You can
think of mass as an object’s heft or, a little more
5 precisely, as the resistance it offers to having its
motion changed. Push on a freight train (or a
feather) to increase its speed, and the resistance you
feel reflects its mass. At a microscopic level, the
freight train’s mass comes from its constituent
10 molecules and atoms, which are themselves built
from fundamental particles, electrons and quarks.
But where do the masses of these and other
fundamental particles come from?
When physicists in the 1960s modeled the
15 behavior of these particles using equations rooted in
quantum physics, they encountered a puzzle. If they
imagined that the particles were all massless, then
each term in the equations clicked into a perfectly
symmetric pattern, like the tips of a perfect
20 snowflake. And this symmetry was not just
mathematically elegant. It explained patterns evident
in the experimental data. But—and here’s the
puzzle—physicists knew that the particles did have
mass, and when they modified the equations to
25 account for this fact, the mathematical harmony was
spoiled. The equations became complex and
unwieldy and, worse still, inconsistent.
What to do? Here’s the idea put forward by Higgs.
Don’t shove the particles’ masses down the throat of
30 the beautiful equations. Instead, keep the equations
pristine and symmetric, but consider them operating
within a peculiar environment. Imagine that all of
space is uniformly filled with an invisible
substance—now called the Higgs field—that exerts a
35 drag force on particles when they accelerate through
it. Push on a fundamental particle in an effort to
increase its speed and, according to Higgs, you would
feel this drag force as a resistance. Justifiably, you
would interpret the resistance as the particle’s mass.
40 For a mental toehold, think of a ping-pong ball
submerged in water. When you push on the
ping-pong ball, it will feel much more massive than it
does outside of water. Its interaction with the watery
environment has the effect of endowing it with mass.
45 So with particles submerged in the Higgs field.
In 1964, Higgs submitted a paper to a prominent
physics journal in which he formulated this idea
mathematically. The paper was rejected. Not because
it contained a technical error, but because the
50 premise of an invisible something permeating space,
interacting with particles to provide their mass, well,
it all just seemed like heaps of overwrought
speculation. The editors of the journal deemed it “of
no obvious relevance to physics.”
55 But Higgs persevered (and his revised paper
appeared later that year in another journal), and
physicists who took the time to study the proposal
gradually realized that his idea was a stroke of genius,
one that allowed them to have their cake and eat it
60 too. In Higgs’s scheme, the fundamental equations
can retain their pristine form because the dirty work
of providing the particles’ masses is relegated to the
environment.
While I wasn’t around to witness the initial
65 rejection of Higgs’s proposal in 1964 (well, I was
around, but only barely), I can attest that by the
mid-1980s, the assessment had changed. The physics
community had, for the most part, fully bought into
the idea that there was a Higgs field permeating
70 space. In fact, in a graduate course I took that
covered what’s known as the Standard Model of
Particle Physics (the quantum equations physicists
have assembled to describe the particles of matter
and the dominant forces by which they influence
75 each other), the professor presented the Higgs field
with such certainty that for a long while I had no idea
it had yet to be established experimentally.
On occasion, that happens in physics. Mathematical
equations can sometimes tell such a convincing tale,
80 they can seemingly radiate reality so strongly, that
they become entrenched in the vernacular of
working physicists, even before there’s data to
confirm them.
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Question : 44
Total: 52
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