Physicists have discovered a transparent, massless, and neutral "demon" particle that could help scientists understand superconductors better, according to a new study by researchers from the University of Illinois Urbana-Champaign. The study, published in the journal Nature on Wednesday, focused on the search for a particle first theorized by physicist David Pines in 1956. In solids, electrons act erratically, combining into collective units. If enough energy is input, the electrons can form plasmons - waves that act somewhat like a particle (also known as a quasiparticle) - if enough energy is input, although usually, the mass of solids is too...