Submillimetric gravity: confronting the modified dynamics with higher-dimensional theories

We propose that future experiments aiming at the detection of deviations from the 1/r2 gravitational law on submillimetric scales can be used to test the modified Newtonian dynamics theory (MOND). Current experiments are able to test the gravitational field of masses m≈1 g at distances r≈200 μm, implying that they are probing accelerations well above the MOND limit (a0≈1.2×10−8 cm s−2). We show that MONDian effects begin to be important at the submillimetric level for masses m⩽1 mg. MOND makes predictions that are clearly distinguishable from those expected in a scenario with compact extra dimensions. This will enable direct confrontation between the two theories if future experiments can improve their mass scales to the milligram level.