Scientists at Duke and Rutgers have advanced an actual falsifiable experiment that could potentially prove the Randall-Sundrum braneworld model of 5-D spacetime. It's all to do with primordial black holes and interference patterns in gamma rays from other galaxies, and I'm sure I'm understanding only a tiny bit of it, but it's a pretty cool idea. We've got only a year or two until their predictions are proven or disproven when the Large Area Space Telescope comes online (assuming that the budget doesn't get cut in the coming months by legislators desperate to give the appearance of doing something).