303 | AMA | February 2025

12677.084 - 12705.001 Sean Carroll

We use, as very often in science or in physics in particular, the same word to mean different things. The overall definition of vacuum to a physicist is, given some theory, what is the lowest energy state of that theory? So in ordinary theories, classical theories, empty space is the lowest energy state, and that matches on to our intuitive idea of what the vacuum is supposed to be, empty space.