Cosmology

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 saw a black hole for the first time, debated the expansion rate of the universe, pondered the origin of time and modeled the end of clouds.

A study challenged the evidence for the mysterious antigravitational force known as dark energy. Then cosmologists shot back.

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.

A close look at fundamental symmetries has exposed hidden patterns in the universe. Physicists think that those same symmetries may also reveal time’s original secret.

The KATRIN experiment is closing in on the mass of the neutrino, which could point to new laws of particle physics and shape theories of cosmology.

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.

The theoretical particle physicist Ann Nelson, who died on August 4 at age 61, was a font of brilliant ideas and a champion of ending discrimination in the field.