KentuckyFC writes: One of the more exciting predictions from "braneworld" theories of high energy physics is that matter can leak out of other universes into our own, and vice versa. The basic idea is that our three-dimensional universe or brane is embedded in a much larger multi-dimensional cosmos. These branes can become coupled so that a quantum particle such as a neutron can exist in a superposition of states in both universes at the same time. When the neutron collides with something, the superposition collapses and the particle must suddenly exist in one brane or the other. That means neutrons from our universe can leak into other branes and then back again. Now physicists are devising an experiment to look for this neutron leakage. They plan to put a well shielded neutron detector next to a shielded nuclear reactor that produces neutrons at a research facility in France. All this shielding means the detector should not see any neutrons from inside the reactor. However, if the neutrons are leaking into another brane and then back into our world, they can bypass this shielding and trigger the detector. The team has not yet set a date for the experiment but the discovery of neutrons (or anything else) leaking into our universe would be huge.