What's up in

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

Physicists theorize that a new “traversable” kind of wormhole could resolve a baffling paradox and rescue information that falls into black holes.

Reductionism breaks the world into elementary building blocks. Emergence finds the simple laws that arise out of complexity. These two complementary ways of viewing the universe come together in modern theories of quantum gravity.

The pot-stirring string theorist and quantum gravity theorist never sits still for long.

Recent calculations tie together two conjectures about gravity, potentially revealing new truths about its elusive quantum nature.

A decades-old method called the “bootstrap” is enabling new discoveries about the geometry underlying all quantum theories.

The effort to unify quantum mechanics and general relativity means reconciling totally different notions of time.

Can a fluid analogue of a black hole point physicists toward the theory of quantum gravity, or is it a red herring?

The story of the universe’s birth — and evidence for string theory — could be found in triangles and myriad other shapes in the sky.