What is a phonon?
Q: What is a phonon?
A: A phonon is a quantized lattice vibration in physics.
Q: What does the word "quantized" mean in physics?
A: In physics, the word quantized means that only certain values of something are allowed.
Q: How can something that is quantized be thought of?
A: 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.
Q: What is a lattice?
A: A lattice is the repeating or periodic structure of a crystal, made up of atoms or molecules in a certain pattern with points on the pattern at which the atoms or molecules are located.
Q: Can solids, liquids, and gases all experience vibrations?
A: Yes, solids, liquids, and gases can all experience vibrations.
Q: Why do phonons exist?
A: 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.
