Gravity

For decades, extremal black holes were considered mathematically impossible. A new proof reveals otherwise.

By studying the geometry of model space-times, researchers offer alternative views of the universe’s first moments.

Black holes are inescapable traps for most of what falls into them — but there can be exceptions. The theoretical physicist Leonard Susskind speaks with co-host Janna Levin about the black hole information paradox and how it has propelled modern physics.

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.

Mathematicians prove a theorem that illuminates the geometry of universes with tiny amounts of mass.

For a half century, mathematicians have tried to define the exact circumstances under which a black hole is destined to exist. A new proof shows how a cube can help answer the question.

For decades, physicists have struggled to develop a quantum theory of gravity. But what if gravity — and space-time — are fundamentally classical?

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

Renate Loll has helped pioneer a radically new approach to quantum gravity. She assumes that the fabric of space-time is a blend of all possible fabrics, and she has developed the computational tools needed to calculate the far-reaching implications of that assumption.