Physics

We don’t know why the universe appears to be expanding faster than it should. New ultra-precise distance measurements have only intensified the problem.

Over the past two years, astronomers have rewritten the story of our galaxy.

The result highlights a fundamental tension: Either the rules of quantum mechanics don’t always apply, or at least one basic assumption about reality must be wrong.

A team in Paris has made the most precise measurement yet of the fine-structure constant, killing hopes for a new force of nature.

Has physics reached the limits of what we can discover — or are the possibilities only just beginning?

Physicists plan to leave no stone unturned, checking whether dark matter tickles different types of detectors, nudges starlight, warms planetary cores or even lodges in rocks.

An exercise in pure mathematics has led to a wide-ranging theory of how the world comes together.

It has been thought of as many things: a pointlike object, an excitation of a field, a speck of pure math that has cut into reality. But never has physicists’ conception of a particle changed more than it is changing now.

The newly-measured rate of a key nuclear fusion process from the Big Bang matches the picture of the universe 380,000 years later.