Theoretical physics

Physicists are translating commonsense principles into strict mathematical constraints on how our universe must have behaved at the beginning of time.

Years of conflicting neutrino measurements have led physicists to propose a “dark sector” of invisible particles — one that could simultaneously explain dark matter, the puzzling expansion of the universe, and other mysteries.

Investigations of the simplest possible clocks have revealed their fundamental limitations — as well as insights into the nature of time itself.

The five-decade-old paradox — long thought key to linking quantum theory with Einstein’s theory of gravity — is falling to a new generation of thinkers. Netta Engelhardt is leading the way.

Theorists are in a frenzy over “fractons,” bizarre, but potentially useful, hypothetical particles that can only move in combination with one another.

The root of today’s quantum revolution was John Stewart Bell’s 1964 theorem showing that quantum mechanics really permits instantaneous connections between far-apart locations.

The Standard Model is a sweeping equation that has correctly predicted the results of virtually every experiment ever conducted, as Quanta explores in a new video.

Chiara Marletto is trying to build a master theory — a set of ideas so fundamental that all other theories would spring from it. Her first step: Invoke the impossible.

Today’s long-anticipated announcement by Fermilab’s Muon g-2 team appears to solidify a tantalizing conflict between nature and theory. But a separate calculation, published at the same time, has clouded the picture.