Quantum gravity

By chewing on the problems posed by “extremal” black holes, physicists have exposed a surprising and universal connection between energy and entropy.

The laws of physics imply that the passage of time is an illusion. To avoid this conclusion, we might have to rethink the reality of infinitely precise numbers.

By considering simple symmetries, physicists working on the “bootstrap” can rediscover the basic form of the known forces that shape the universe.

For the first time, physicists have calculated exactly what kind of singularity lies at the center of a realistic black hole.

Lurking behind Einstein’s theory of gravity and our modern understanding of particle physics is the deceptively simple idea of symmetry. But physicists are beginning to question whether focusing on symmetry is still as productive as it once was.

Opinions differ about what recent measurements of a sound-trapping fluid reveal about light-trapping black holes.

Physicists have devised a holographic model of “de Sitter space,” the term for a universe like ours, that could give us new clues about the origin of space and time.

Perfect black holes are versatile mathematical tools. Just don’t mistake them for the real thing.

The same codes needed to thwart errors in quantum computers may also give the fabric of space-time its intrinsic robustness.