Theoretical physics

String theory has so far failed to live up to its promise as a way to unite gravity and quantum mechanics. At the same time, it has blossomed into one of the most useful sets of tools in science.

The astrophysicist Tracy Slatyer is searching for faint wisps of dark matter annihilating in the early universe — and perhaps in hiding places closer to home.

The absence of supersymmetry particles at the Large Hadron Collider has settled a 16-year-old bet among physicists.

Physicists are confronting their “nightmare scenario.” What does the absence of new particles suggest about how nature works?

The physicist-mathematician Miranda Cheng is working to harness a mysterious connection between string theory, algebra and number theory.

The physicist Asimina Arvanitaki is thinking up ways to search gravitational wave data for evidence of dark matter particles orbiting black holes.

According to our best theories of physics, the universe is a fixed block where time only appears to pass.

Richard Feynman's famous diagrams weren’t just a way to do calculations. They represented a deep shift in thinking about how the universe is put together.

Rampant rumors and a new analysis undercut hopes of a major discovery at the Large Hadron Collider.