In this talk I will discuss a simple model of 2d flat gravity that derives from the CGHS model. Its simplicity allows one to compute exactly the Euclidean gravitational path integral. When one allows for more than one thermal boundary, the model is dual to an ensemble of theories, I will discuss this ensemble in detail. The ensemble description is equivalent to a description in terms of baby universe Hilbert space in which one can build the so-called alpha-states, states in which the theory is now dual to only one theory. I will end the presentation by describing how this 2d model appears as a universal sector in the near-horizon dynamics of non-extremal black holes.
Charles Marteau (British Columbia): From baby universes to black holes in 2d flat space gravity
