Scientists "totally surprised" by "significant shake-up."

Kate Ravilious
for National Geographic News
Published July 7, 2010

Protons, among the building blocks of atoms, are even smaller than we thought—and the unexpected discovery may alter some of the most trusted laws of physics.
All atoms are made up of nuclei orbited by electrons. The nuclei, in turn, are made of neutrons and protons, which are themselves made of particles called quarks. (Related: "'God Particle' May Be Five Distinct Particles, New Evidence Shows.")
For years the accepted value for the radius of a proton has been 0.8768 femtometers, where a femtometer equals one quadrillionth of a meter.
The size of a proton is an essential value in equations that make up the 60-year-old theory of quantum electrodynamics, a cornerstone of the Standard Model of particle physics. The Standard Model describes how all forces, except gravity, affect subatomic particles. (See "Einstein's Gravity Confirmed on a Cosmic Scale.")
But the proton's current value is accurate only by plus or minus one percent—which isn't accurate enough for quantum electrodynamics, or QED, theory to work perfectly. So physicists have been searching for ways to refine the number...

Source: National Geographic