Quotes About Leptons

The leptons most familiar to the non-physicist are the electron and perhaps the neutrino; and the most familiar quarks are . . . well, there are no familiar quarks.

Shortly before, during, and after the strong and electroweak forces parted company, the universe was a seething soup of quarks, leptons, and their antimatter siblings, along with bosons, the particles that enable their interactions.

During the quark–lepton era the universe was dense enough for the average separation between unattached quarks to rival the separation between attached quarks.

At this point, the particles came in two types, called quarks—which rhymes with marks—and leptons. Quarks are quirky beasts. You'll never catch a quark all by itself; it will always be clutching others nearby. I'm sure you have at least one friend or classmate who behaves similarly. Quarks are like those kids who never want to do anything alone, not even walk to the restroom.

All of the lightest stable quarks and leptons have heavier replicas. No one knows why they are there, or what they are good for. When physicists first realized that the muon, a particle first seen in cosmic rays, was nothing other than a heavier version of the electron (200 times heavier), the physicist I.I. Rabi asked, "Who ordered that?

However, you will need to know about flavors and generations because of the strong constraints on the particles' properties, which give us vital clues and constraints on the physics that lies beyond the Standard Model. Chief among these constraints is that different flavors of quarks and leptons with the same charges rarely, if ever, turn into one another.

In a supersymmetric universe, the partners of quarks and leptons would be new bosons. Physicists, who enjoy whimsical (but systematic) nomenclature, call them squarks and sleptons.