Theoretical physics

Promise and controversy continues to surround string theory as a potential unified theory of everything. In the latest episode of The Joy of Why, Cumrun Vafa discusses his progress in trying to find good, testable models hidden among the ‘swampland’ of impossible universes.

Black hole and Big Bang singularities break our best theory of gravity. A trilogy of theorems hints that physicists must go to the ends of space and time to find a fix.

In math and computer science, researchers have long understood that some questions are fundamentally unanswerable. Now physicists are exploring how even ordinary physical systems put hard limits on what we can predict, even in principle.

The reference frames from which observers view quantum events can themselves have multiple possible locations at once — an insight with potentially major ramifications.

Curious connections between physics and math suggest to Latham Boyle that space-time may survive the jump to the next theory of reality.

A decade after the discovery of the “amplituhedron,” physicists have excavated more of the timeless geometry underlying the standard picture of how particles move.

A 1930s-era breakthrough is helping physicists understand how quantum threads could weave together into a holographic space-time fabric.

A black hole formula worked out in the 1970s remains the most concrete clue physicists have about the threads of the space-time fabric.

These three imagined scenarios lead many physicists to doubt that space-time is fundamental.