Cosmology

The newly developed theory of emergent gravity, proposed as an alternative to dark matter, struggles in one of its first trials.

A different kind of dark matter could help to resolve an old celestial conundrum.

A series of observations at the very edge of the universe has reignited a debate over what lifted the primordial cosmic fog.

After a surprise discovery, astrophysicists are racing to understand superenergetic flashes of radio waves that sometimes beep out from distant galaxies.

A proposed theory of gravity does away with dark matter, even as new astrophysical findings challenge the need for galaxies full of the invisible mystery particles.

A camera lens often used by wildlife and sports photographers has helped astronomers learn about dark matter and galaxy formation.

String theory has so far failed to live up to its promise as a way to unite gravity and quantum mechanics. At the same time, it has blossomed into one of the most useful sets of tools in science.

According to our best theories of physics, the universe is a fixed block where time only appears to pass.

The story of the universe’s birth — and evidence for string theory — could be found in triangles and myriad other shapes in the sky.