Dark matter

Modified gravity theories have never been able to describe the universe’s first light. A new formulation does.

Researchers say there are three possible explanations for the anomalous data. One is mundane. Two would revolutionize physics.

Physicists have proposed extra cosmic ingredients that could explain the faster-than-expected expansion of space.

In a new paper, physicists argue that hypothetical particles called axions could explain why the universe isn’t empty.

A photograph of the infant cosmos reveals the precise amounts of dark matter and dark energy in the universe, leaving precious little room for argument.

Physicists have long searched for hypothesized dark matter particles called WIMPs. Now, focus may be shifting to the axion — an ultra-lightweight particle whose existence would solve two mysteries at once.

Most every cosmologist believes the universe is flat. A new analysis argues that it’s closed.

The astronomers Michel Mayor and Didier Queloz won half of the prize for their 1995 discovery of a Jupiter-like planet orbiting a nearby star. The cosmologist James Peebles won the other half for work exploring the structure of the universe.

New measurements could upend the standard theory of the cosmos that has reigned since the discovery of dark energy 21 years ago.