Physics

It weighs as much as 780 million suns and helped to cast off the cosmic Dark Ages. But now that astronomers have found the earliest known black hole, they wonder: How could this giant have grown so big, so fast?

Edward Witten reflects on the meaning of dualities in physics and math, emergent space-time, and the pursuit of a complete description of nature.

Astronomers generally stay away from the “Zone of Avoidance.” When one astronomer didn’t, she found a giant cosmic structure that could help explain why our galaxy moves so fast.

New data tracking the movements of millions of Milky Way stars have effectively ruled out the presence of a “dark disk” that could have offered important clues to the mystery of dark matter.

A number of high-energy anomalies raised hopes that astrophysicists had seen their first direct glimpses of dark matter. New studies suggest a different source may be responsible.

Astronomers are mystified by a strange star explosion in a distant galaxy that might be a relic from an earlier cosmological era.

The Zoomable Universe, a new book by the astrobiologist Caleb Scharf, the illustrator Ron Miller and 5W Infographics, tours the universe’s 62 orders of magnitude.

The core of a neutron star is such an extreme environment that physicists can’t agree on what happens inside. But a new space-based experiment — and a few more colliding neutron stars — should reveal whether neutrons themselves break down.

Newly discovered “standard sirens” provide an independent, clean way to measure how fast the universe is expanding.