AN INVENTORY OF THE QUANTUM REALM.

ELECTRONS Weighing in around 1800 times lighter than protons or neutrons, electrons add very little to the overall mass of atoms. Like a musical string, which can express different tones, a particle string can "sound" like a quark, or an electron, or a photon, or any other particle in the current standard model. SPARTICLES In particle physics terms, matter and force are different only in as much as matter particles take up space, whereas force particles don't (see "The exclusion principle", page 40). In the case of electromagnetism, when an electron encounters another electron, the first electron emits a photon, the force-carrying particle As the first electron recoils, the other absorbs the photon such that it too changes direction, and the two electrons bounce off one another Many questions surround the Higgs. [Extracted from the article]