What’s called the Standard Model, one of the signature creations of quantum physics, is very good at explaining the workings of three of the four known forces in the universe: electromagnetism; the strong, or nuclear force, that binds together the nuclei of atoms; and the weak force, which is manifest in radioactive decay. But the Standard Model does not account for gravity; Einstein’s theory does.

General relativity explains how gravity controls and shapes the galaxies and the stars and predicts their movements. But, conversely, general relativity does not address what happens in the subatomic world.

That is where the work of Dr. Gubser and others has come in, with its focus on string theory.

String theory postulates that fundamental particles aren’t particles at all — that they are actually strings, existing in loops or with loose ends. Those strings vibrate and bend and connect to one another in myriad ways, propagating in multiple dimensions that we cannot see. (In the most prevalent version of the theory, there are 10 dimensions — nine existing in space and one in time.)

String theory — the so-called “theory of everything” — has never been confirmed through experiments, but the work of Dr. Gubser and others has found a mathematical correspondence between string theory and a class of quantum models akin to the Standard Model of particle physics. That means that string theory could be used to solve problems in traditional quantum theory and that, conversely, traditional quantum theory could be used to describe quantum gravity — the missing force in the Standard Model.

This correspondence has been “one of the turning points in theoretical physics of the last 30 or 40 years,” said Dr. Igor Klebanov, director of the Princeton Center for Theoretical Science, who taught Dr. Gubser as a graduate student — “by far the best student in the class,” he said — and collaborated with him on research papers.