Millimeter Range Forces in Superstring Theories with Weak - Scale Compactification

We show that theories, in which supersymmetry is broken via Scherk-Schwarz com-pactification at the weak scale, possess at least one scalar particle with Compton wavelength in the millimeter range which mediates a force with strength 1/3 of gravity. Such forces are going to be explored in upcoming experiments using micro-electromechanical systems or cantilever technology. We also present a simple way of understanding some decoupling aspects of these theories by analogy with finite temperature field theory.