Weak and Strong Interactions

The weak force and strong force are two of the four fundamental forces that govern all matter in the universe. The other two are gravity and the electromagnetic force. The weak force operates at extremely short distances on the subatomic level and is responsible for processes like beta decay. In beta decay, a neutron inside a nucleus transforms into a proton, expelling an electron (called a beta particle) and an anti-neutrino. These two particles are the products of decay of another particle known as the W boson, which is highly unstable. The strong force is responsible for holding the nucleus together and arises from the color charge of quarks, the fundamental particles that make up hadrons (such as protons and neutrons). Quarks have a property known as color charge, which is unrelated to the colors we perceive with our eyes but represents a type of charge in quantum mechanics. Quarks within a hadron must combine in such a way that their color charges result in a color-neutral particle (i.e., red + green + blue = colorless). Quarks are constantly changing their color and exchanging particles known as gluons. These gluons mediate the interactions between quarks, binding them together in the nucleus.