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.