Lasers

There are only about 100 different kinds of atoms in the entire universe. Everything we see is made up of these 100 atoms in an unlimited number of combinations. They continuously vibrate, move and rotate. Even the atoms that make up the chairs that we sit in are moving around in class. Atoms can be in "different states of excitation" (Bertolotti 48) or they can have different energies. If we apply a lot of energy to an atom, it can leave what is called the ground-state energy level and go to an excited level. …