He was awarded the 2020 Nobel Prize in Physics "for the discovery of a supermassive compact object at the centre of our galaxy", which he shared with Andrea Ghez and Roger Penrose.

He was a Miller Fellow from 1980 until 1982, and also Associate and finally Full Professor in the Department of Physics at the University of California, Berkeley from 1981.

In 1986, he left Berkeley to become a director at the Max Planck Institute for Extraterrestrial Physics in Garching and Scientific Member of the Max-Planck-Gesellschaft.

They used these to track the motions of stars at the centre of the Milky Way, around Sagittarius A*, and show that they were orbiting a very massive object, now known to be a black hole.

This allowed them to test the redshift predicted by general relativity at relativistic velocities, finding additional confirmation of the theory.