Natalie Wolchover

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.

Like a perpetual motion machine, a time crystal forever cycles between states without consuming energy. Physicists claim to have built this new phase of matter inside a quantum computer.

For 50 years, mathematicians have believed that the total number of real numbers is unknowable. A new proof suggests otherwise.

Supermassive black holes emit jets of white-hot plasma that stretch thousands of light-years across the cosmos. For the first time, researchers have identified what’s creating these jets.

Ultrahigh-energy cosmic rays twist and turn on their way to Earth, which has made it nearly impossible to identify the colossal monsters that create them.

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.

Spurred on by quantum experiments that scramble the ordering of causes and their effects, some physicists are figuring out how to abandon causality altogether.

Twenty years ago, physicists set out to investigate a mysterious asymmetry in the proton’s interior. Their results, published today, show how antimatter helps stabilize every atom’s core.