Nima Arkani-Hamed gave a talk on ‘Revenge of the S-Matrix: What is the simplest QFT?’
He talked about how many of the fundamental theoretical problems in physics such as determining the vacuum, the information paradox, and infinities that arise in eternal inflation come about because of problems with locality and gravity. Because of gravity, he says, locality is not an exact principle of our world. The pragmatic reason for considering such theories is that locality gives rise to a huge amount of redundancy.
He then reviewed a different way of talking about QFT which was not manifestly local, called BCFW, where you analytically continue the momenta of an incoming and an outgoing particle in some scattering process. The result was that in this formalism, N=8 SUGRA becomes the simplest QFT.
His talk is online here.
High Energy Mayhem 