Hubble constant

By measuring the universe’s emptiest spaces, scientists can study how matter clumps together and how fast it flies apart.

The James Webb Space Telescope has the potential to rewrite the history of the cosmos and reshape humanity’s position within it. But first, a lot of things have to work just right.

We don’t know why the universe appears to be expanding faster than it should. New ultra-precise distance measurements have only intensified the problem.

Cosmologists have concluded that the universe doesn’t appear to clump as much as it should. Could both of cosmology’s big puzzles share a single fix?

Astronomers are discovering that magnetic fields permeate much of the cosmos. If these fields date back to the Big Bang, they could solve a major cosmological mystery.

Physicists have proposed extra cosmic ingredients that could explain the faster-than-expected expansion of space.

A problem confronts cosmology: Two independent measurements of the universe’s expansion give incompatible answers. Now a third method, advanced by an astronomy pioneer, appears to bridge the divide.

New measurements could upend the standard theory of the cosmos that has reigned since the discovery of dark energy 21 years ago.

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.