Cosmology

An idea derived from string theory suggests that dark matter is hiding in a (relatively) large extra dimension. The theory makes testable predictions that physicists are investigating now.

As measurements of distant stars and galaxies become more precise, cosmologists are struggling to make sense of sparring values.

From the smallest scales to the largest, the physical world provided no shortage of surprises this year.

To catch even a whiff of the universe’s earliest epochs — an age of darkness, and one of new light — Cynthia Chiang builds her own equipment. Then she deploys it at the ends of the Earth.

Even empty space bubbles with energy, according to quantum mechanics — and that fact affects almost every facet of physical reality. The theoretical physicist Isabel Garcia Garcia explains to Steven Strogatz why it’s so important in modern physics to understand what a true vacuum is.

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

Astronomers have found a background din of exceptionally long-wavelength gravitational waves pervading the cosmos.

Several areas of physics suggest reasons to think that unobservable universes with different natural laws could lie beyond ours. The theoretical physicist David Kaplan talks with Steven Strogatz about the mysteries that a multiverse would solve.

Cosmologists are using secondary signatures from the cosmic microwave background to map the universe’s hidden matter.