Experimental hints of Gravity in Large Extra Dimensions

Recent conjectures suggest the universe may have large extra dimensions, through which gravity propagates. This implies gross departures from Newton's law of gravity at small length scales. Here I consider some implications for particle dynamics on scales comparable to the compactification radius, $R_c \ltorder 1$ mm. During planet formation, coalescence of micron sized dust grains to planetesimals is a rate critical step. Blum et al (2000) found dust grain aggregates form low fractal dimension structures in microgravity, consistent with high angular momentum coalescence. I consider the effects of non-Newtonian gravity on dust aggregation on scales less than $R_c$ and show they naturally coalesce into low dimensional structures with high specific angular momentum. We infer $R_c \approx 80$ microns.