MEASURING SMALL DISTANCES IN N = 2 SIGMA-MODELS

We analyze global aspects of the moduli space of Kahler forms for N = (2,2) conformal sigma-models. Using algebraic methods and mirror symmetry we study extensions of the mathematical notion of length (as specified by a Kahler structure) to conformal field theory and calculate the way in which lengths change as the moduli fields are varied along distinguished paths in the moduli space. We find strong evidence supporting the notion that, in the robust setting of quantum Calabi-Yau moduli space, string theory restricts the set of possible Kahler forms by enforcing ''minimal length'' scales, provided that topology change is properly taken into account. Some lengths, however, may shrink to zero. We also compare stringy geometry to classical general relativity in this context.