The supermassive black hole has been identified, but her explorations are far from over. Theories of galactic evolution suggest that the Milky Way’s center should have lots of old stars and almost no young stars. Observations show the opposite. Ghez’s group is also tracking a mysterious, glowing infrared blob called G2 that skimmed past the black hole in 2014. And now, using their decades-long data set, her team has begun testing whether the stars orbiting the black hole move according to the rules of Einstein’s general relativity or are subject to exotic deviations from theory.

Quanta caught up with Ghez to hear about these projects and her plans. The interview has been edited and condensed for clarity.

You use new telescope technology to address deep theoretical questions. Which one comes first for you: observation or theory?

I think that’s a great question about creativity and discovery. Like, how do you figure out your next project? For me, what floats my boat the most is to figure out new ways of seeing things; to reveal puzzles. What makes me happiest is when observations don’t make sense. And in order for observations to not make sense in a new way — in other words to not be doing incremental work — you need to be looking in a way that’s different.

Your team and Reinhard Genzel’s group disagreed about how to interpret the observations of G2. They thought it was a gas cloud; your group suggested it was a star. Can you walk us through what happened when it passed the black hole in 2014?

I was pretty convinced that you could explain this object with a model in which you said the object was actually intrinsically a star. One of the key determinants of whether it was a pure gas cloud or a star was whether or not it survived closest approach in 2014. It happily survived.

The interpretation that I am most intrigued by is the idea that you are seeing an object that began its life as a binary star. And if you put very close binaries near a black hole, it turns out to induce what’s known as a three-body interaction, and the binary can merge. So black holes can drive binaries to merge more quickly than they would anywhere else in our galaxy. You end up with an object that has the characteristics of what we are looking at.