The Lightness of Being: Mass, Ether, and the Unification of Forces

So there are two competing effects, which pull in opposite directions. To cancel the field disturbance accurately and minimize that energy cost, Nature wants to localize the antiquark on the quark. But to minimize the quantum-mechanical cost of localizing a position, Nature wants to let the antiquark wander a bit.

As with any compromise, the result is—well, a compromise. Nature can’t make both energies zero simultaneously. So the total energy won’t be zero. Actually there can be different accommodations that are more-or-less stable. Each will have its own nonzero energy E. And thus, according to Einstein’s second law, each will have its own mass, m = E/c2. A

we see atomic spectra, but we weigh hadron spectra.

In Figure 17.1, the weak interaction makes transformations in the vertical direction. (The strong interaction makes transformations in the horizontal direction.)

Nature compromises. She finds ways of striking a balance between the demands of the gluon fields that don’t want to be disturbed, and those of the quarks and antiquarks that want to roam free. (You might think of a family gathering where the gluon fields are the old curmudgeons, the quarks and antiquarks are the rambunctious kids, and Nature is the

Sherlock Holmes and Dr. Watson were on a camping trip. After pitching tent beneath a skyful of stars, they went to sleep. In the middle of the night Holmes shook Watson awake, and asked him, “Watson, look up at the stars! What do they tell us?” “They teach us humility. There must be millions of stars, and if even a small fraction of those have plan

the years of searching in the dark for a truth that one feels, but cannot express; the intense desire and the alternations of confidence and misgiving, until one breaks through to clarity and understanding, are only known to him who has himself experienced them.