Is the law of universal gravitation valid at short distances?

Recently, short-range macroscopic forces superimposed to gravity have been conjectured. We argue that their existence is unavoidable if gravity has to be merged with the other fundamental interactions within the currently accepted paradigms for unification. A first attempt to detect such forces in the macroscopic range using micromechanical resonators is reported, together with a discussion of further sensitivity improvements. Implications of the possible discovery of these new interactions in elementary particle physics and cosmology are outlined.