“Very much, string theory is simply a work in progress. What we are inching toward every day are predictions that within the realm of current technology we hope to test. It's not like we're working on a theory that is permanently beyond experiment. That would be philosophy.”

American physicist, professor, and science festival chairman

Brian Greene is an American physicist and professor of physics and mathematics at Columbia University. He is known for his work on string theory and for co-founding the World Science Festival in 2008. He directs Columbia’s Center for Theoretical Physics and serves as chairman of the festival. Greene also co-discovered mirror symmetry, a relation between two different Calabi-Yau manifolds, and described the flop transition and the conifold transition, showing how topology can change smoothly in string theory.