Cosmology

For decades, astronomers weren’t able to find all of the atomic matter in the universe. A series of recent papers has revealed where it’s been hiding.

A controversial new paper argues that universes with dark energy profiles like ours do not exist in the “landscape” of universes allowed by string theory.

If and when physicists are able to pin down the metal content of the sun, that number could upend much of what we thought we knew about the evolution and life span of stars.

Computer simulations have become so accurate that cosmologists can now use them to study dark matter, supermassive black holes and other mysteries of the real evolving cosmos.

An experiment at the Fermi National Accelerator Laboratory near Chicago has detected far more electron neutrinos than predicted — a possible harbinger of a revolutionary new elementary particle called the sterile neutrino, though many physicists remain skeptical.

A roundup of some of the most important discoveries gleaned so far from the Gaia space observatory’s new map of the galaxy.

Two ways of measuring the universe’s expansion rate yield two conflicting answers. Many point to the possibility of new physics at work, but a new analysis argues that unseen errors could be to blame.

A surprise discovery announced a month ago suggested that the early universe looked very different than previously believed. Initial theories that the discrepancy was due to dark matter have come under fire.

The amount of energy infusing empty space seems too small to explain without a multiverse. But physicists have at least one alternative left to explore.