Cosmology

Physicists are beginning to unravel the mysteries of ultrahigh-energy cosmic rays, particles accelerated by the most powerful forces in the universe.

Imagine the fabric of space-time peeled back layer by layer.

New tools may reveal how quantum information builds the structure of space.

A bold new idea aims to link two famously discordant descriptions of nature. In doing so, it may also reveal how space-time owes its existence to the spooky connections of quantum information.

Is dark energy a cosmic chameleon that can fade into its surroundings? A recent test brings the mysterious anti-gravitational force down to earth.

No definitive evidence for cosmic inflation is found, but support remains strong for the theory even as critics highlight its shortcomings as an explanation for how and why the universe began.

Early in cosmic history, our universe may have bumped into another — a primordial clash that could have left traces in the Big Bang’s afterglow.

Testing the multiverse hypothesis requires measuring whether our universe is statistically typical among the infinite variety of universes. But infinity does a number on statistics.

For five years physicists have been tantalized by possible evidence of dark matter in the Milky Way’s center. But new results from small satellite galaxies have complicated the story.