String theory

Decades after physicists happened upon a stunning mathematical coincidence, researchers are getting close to understanding the link between two seemingly unrelated geometric universes.

The theoretical physicist Joe Polchinski, who died February 2, left a tremendous professional and personal legacy, says a friend and collaborator.

The mother of all string theories passes a litmus test that, so far, no other candidate theory of quantum gravity has been able to match.

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

A type of symmetry so unusual that it was called a “pariah” turns out to have deep connections to number theory.

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.

To begin to understand what mathematicians and physicists see in the abstract structures of symmetries, let’s start with a familiar shape.

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

Daily bike rides, serendipitous interactions and long periods of solo thinking inspire this string cosmologist.