general relativity

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.

Inside of a black hole, the two theoretical pillars of 20th-century physics appear to clash. Now a group of young physicists think they have resolved the conflict by appealing to the central pillar of the new century — the physics of quantum information.

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.

In three-dimensional space, the surface of a black hole must be a sphere. But a new result shows that in higher dimensions, an infinite number of configurations are possible.

Albert Einstein’s ideas about space-time aren’t exactly intuitive, and they aren’t exactly Einstein’s, either.

The solutions to Einstein’s equations that describe a spinning black hole won’t blow up, even when poked or prodded.

Surprising as it may sound, 107 years after the introduction of general relativity, the meanings of basic concepts are still being worked out.