The discovery of gravitational waves has been perhaps the biggest moment in science since the discovery of the Higgs boson — but what exactly are they and what makes them so important? A physicist was on the Late Show with Stephen Colbert to break it down for everyone in America.

Theoretical physicist Brian Greene was on Colbert’s show to explain the complex world of physics in layman’s terms. He’s know for books like The Elegant Universe as he acts as sort of an ambassador between the complex world of scientists and laboratories and everyday people.

Green was there to discuss the discovery of gravitational waves by scientists using the Laser Interferometer Gravitational Wave Observatory (LIGO). You can watch the video below for the explanation. As a bonus, he also uses green lasers to show how LIGO works.

In other developments on gravitational waves, the Rochester Institute of Technology is exploring the subject in a series of upcoming papers, the school announced in a statement.

“LIGO has just proved that binary black holes merge frequently throughout the universe, much more than many people expected,” Richard O’Shaughnessy, assistant professor in the School of Mathematical Sciences, said in the statement. “But the discovery of a black hole merger is only the tip of the iceberg.”

The statement notes that there are many more things to discover: “An individual rapidly spinning neutron star can produce weaker gravitational waves generated by irregularities in its structure. A single neutron star can continuously emit periodic signals in contrast to the short-lived ‘chirps’ that merging pairs of black holes or neutron stars emit.”