What is Phonon?
In [[physics]], a '''phonon''' is a '''quantized lattice vibration'''. The word '''quantized''' is used in physics to mean that only certain values of something are allowed. Something that is quantized can be thought of as stairs; you can only move from step to step and you can't stand in between steps. Something that is not quantized can be thought of as a ramp or smooth incline; you can move any distance up or down. A '''lattice''' is the repeating or [[periodic]] structure of a [[crystal]]. A crystal is made up of [[atoms]] or [[molecules]] in a certain pattern. The points on the pattern at which the atoms or molecules are located is the '''lattice'''. Solids, liquids, and gases can all experience [[vibration|vibrations]]. A vibration being quantized means that only certain [[frequency|frequencies]] of vibrations are allowed. Intuitively, there is no reason for lattice vibrations to be quantized. The [[macroscopic]] or large-scale vibrations of a material are not quantized and can take on essentially any frequency. It is only when we consider the tiny vibrations of the particles that make up a material—atoms and molecules—that the concept of quantization and phonons becomes important. To understand why phonons exist, complicated [[quantum mechanics]] is needed. Without going into too much detail, the interactions between the constituent atoms or molecules of a crystal are analyzed quantum mechanically. Because of their arrangement in a pattern that repeats, when one arrives at a mathematical expression for the frequency of [[oscillation]], one finds that there are only distinct quantized values allowed.<!-- There is unfortunately no simple way to explain this.--> {{Particles}} [[Category:Physics]]