Science Made Simple: What Is Symmetry in Physics?

What Is Symmetry in Physics?
In physics, symmetry refers to how particles behave when space, time, or quantum numbers are reversed. We’re used to seeing simple types of symmetry in everyday life. For example, a human face is very nearly symmetrical when reflected left to right. But a face is completely asymmetric when reflected top to bottom—the top half of a face doesn’t look the same as the bottom. Small changes can break symmetry. For example, a face with a mole on one cheek would break left right symmetry.

Symmetry in physics is about more than just appearance and form. This is in contrast to symmetry in biology, which often refers to symmetry when discussing how organisms look and how their bodies are arranged.