弦理论从第一性原理重建

Physicists find that minimal assumptions about nature inevitably lead to stringlike theories ZACK SAVITSKY F or decades, string theory promised a “theory of every- thing” that described all particles and forces as tiny vibrating strings. Physicists hoped it could also solve one of the field’s deep- est problems: reconciling quantum mechanics with gravity. But as string theory grew increasingly elaborate— and experimentally unreachable— many physicists lost hope. Now, some researchers are revisit- ing the theory from first principles. In a paper in press at Physical Review Letters, Clifford Cheung, a physicist at the California Institute of Technology, and colleagues lay out a small set of assumptions about the universe and show that they inevitably give rise to string theory. …