There is a no-go theorem stating that de Sitter (dS) space cannot be supersymmetric, unless the theory violates unitarity. The nonunitary can manifest itself for instance by the presence of ghost fields. The speaker points out that Vasiliev’s bosonic higher spin gravity evades the assumptions of the no-go theorem and provides evidence that dS space can be consistently supersymmetrized. This relates to the fact that the supersymmetric AdS-Vasiliev/U(N) model duality can be consistently Wick-rotated into a supersymmetric dS-Vasiliev/U(-N) duality, providing a concrete supersymmetric dS/CFT duality. After providing an introduction to the concepts of the Hartle-Hawking wavefunction and dS/CFT, he uses dS/CFT to compute the dS Hartle-Hawking wavefunction for a range of deformations. He shows that the wavefunction is peaked at undeformed dS space and large deformations are suppressed, indicating an absence of ghosts. He speculates on the possibility of a stringy interpretation of dS/CFT in terms of exotic string theories.
