How do we know the fundamental constants are constant? We don’t.

Through a variety of tests on Earth and throughout the universe, physicists have measured no changes in time or space for any of the fundamental constants of nature.

All of modern physics rests on two main pillars. One is Einstein’s theory of general relativity, which we use to explain the force of gravity. The other is the Standard Model, which we use to describe the other three forces of nature: electromagnetism, the strong nuclear force and the weak nuclear force. Wielding these theories, physicists can explain vast swaths of interactions throughout the universe.