Cosmology

Galaxies come in many shapes and sizes, and trying to define them is difficult

If dark energy is weakening, as suggested by recent results, then the cosmos is far stranger than most physicists had supposed

In just the first 259 days of data collection, KATRIN, a beta-decay-based detector in Germany, has set the smallest upper limit yet on the mass of the neutrino—the universe’s lightest massive particle

Nicknamed the “Big Wheel,” a giant, spiral-shaped disk galaxy was spotted in an unusually crowded part of the early universe just two billion years after the big bang

After netting the world’s highest-paying science award, preeminent theoretical physicist Gerard ’t Hooft reflects on his legacy and the future of physics

The spins of some early galaxies could be a clue that the entire observable universe exists within a black hole—except, that is, for all the evidence to the contrary

A long-simmering disagreement over the universe’s present-day expansion rate shows no signs of resolution, leaving experts increasingly vexed

A new map of cosmic expansion suggests that dark energy evolves over time, hinting that the universe doesn’t work the way we thought it did

The final results from the Atacama Cosmology Telescope offer the sharpest, most sensitive view of the early cosmos that anyone has ever seen

New simulations suggest that habitable worlds could have begun forming only 200 million years after the big bang

A nearly century-old offshoot of Einstein’s general theory of relativity may hold promise for solving the mysteries of dark matter, dark energy and more

Physicists are finding new ways to model false vacuum decay, a terrifying, albeit remote, cosmic endgame