CMB

Physicists are translating commonsense principles into strict mathematical constraints on how our universe must have behaved at the beginning of time.

The recent discovery of some of the first galaxies in the universe illuminates the darkest era in cosmic history.

A photograph of the infant cosmos reveals the precise amounts of dark matter and dark energy in the universe, leaving precious little room for argument.

Most every cosmologist believes the universe is flat. A new analysis argues that it’s closed.

Astronomers have known where the universe’s missing matter has been hiding for the past 20 years. So why did it take so long to find it?

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.

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.

The cosmologist David Spergel explains why a widely publicized gravitational-wave discovery could be wrong, and how the “overreaching” study could affect the public’s perception of science.