In this talk I will review a recent reformulation of string theory which does not rely on an a priori space-time interpretation or a pre-assumption of locality and include form the onset stringy symmetries such as T-duality.
I will explain how this resulting theory, called metastring, leads to formulation where the string is chiral and the target is phase space instead of space-time. I will discuss metastring theory on a flat background and summarize a variety of technical and interpretational ideas. These include a discussion of moduli space of Lorentzian worldsheets, a generalization of the world sheet renormalisation group, a description of the geometry of phase space, a study of the symplectic structure and of closed and open boundary conditions, and the string spectrum and operator algebra.
What emerges from these studies is a new quantum notion of space-time that we call modular space-time. This new geometrical concept is fundamental quantum and modular. It is closely linked with T-duality and implements in a precise way a notion of relative locality