Last year, Harvard University physicist Howard Georgi proposed the existence of a strange new kind of matter he dubbed “unparticle stuff.” Unlike ordinary particles, which increase in mass as they increase in energy, unparticles are unconstrained bundles of energy and momentum. Georgi compares unparticles to a system of photons, which remain massless no matter how energized they become because they never had any mass to start with. What makes the unparticle different from the photon is that it can have any mass, depending on how you measure it. According to Georgi, if unparticles exist, they would interact with ordinary matter so weakly they could be detected only in the Large Hadron Collider (LHC), the superpowered particle accelerator scheduled to begin operating later this year.