Quarks
Year of Discovery: 1962
What Is It? Subatomic particles that make up protons and neutrons.
Who Discovered It? Murry Gell-Mann
Why Is This One of the 100 Greatest?
First scientists identified plant fibers, then individual cells. Then scientists conceived of
atoms and molecules. In the early twentieth century, scientists discovered electrons and then
the existence of protons and neutrons. In each case, scientists believed that they had finally
discovered the smallest possible particle of matter. Each time this belief proved wrong.
The discovery of quarks (fundamental particles that make up protons and neutrons) in
1962 led science into the bizarre and alien quantum world inside protons and neutrons, a
world of mass with no mass and where mass and energy are freely exchanged. This discovery
has taken science one giant step closer to answering one of the most basic questions of all:
What really is matter made of? At each new level the answer and the world grows stranger.
How Was It Discovered?
As the nineteenth century closed, Marie Curie broke open the atom and proved that it
was not the smallest possible particle of matter. Soon scientists had identified two subatomic particles: electrons and protons. In 1932 James Chadwick discovered the neutron.
Once again scientists thought they had uncovered the smallest particles of all matter.
When particle accelerators were invented in the mid-1930s, scientists could smash
neutrons into protons, and protons into heavier nuclei to see what the collisions would produce. In the 1950s Donald Glaser invented the “bubble chamber.” Subatomic particles were
accelerated to near light speed and flung into this low-pressure, hydrogen-gas-filled chamber. When these particles struck a proton (a hydrogen nucleus), the proton disintegrated into
a host of strange new particles. Each of these particles left a telltale trail of infinitesimally
small bubbles as they sped away from the collision site. Scientists couldn’t see the particles
themselves. But they could see the trails of bubbles.
Scientists were both amazed and baffled by the variety and number of these tiny tracks
on bubble chamber plots (each indicating the temporary existence of a previously unknown
particle). They were unable to even guess at what these new subatomic particles were.
Murry Gell-Mann was born in Manhattan in 1929. A true prodigy, he could multiply
large numbers in his head at age three. At seven, he beat twelve-year-olds in spelling bees.
By age eight, his intellectual ability matched that of most college students. Gell-Mann,
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