WE SEEM TO BE ENCOUNTERING A LOT OF NEW THINGS IN PHYSICS LATELY: Scientists Catch “Virtual Particles” Hopping In and Out of Existence. The quantum effect known as vacuum birefringence was predicted in the 1930s, but this is the first observational evidence of the phenomenon in action. “Quantum electrodynamics (QED) describes the relationships between particles of light, or photons, and electrically charged particles such as electrons and protons. The theories of QED suggest that the universe is full of “virtual particles,” which are not really particles at all. They are fluctuations in quantum fields that have most of the same properties as particles, except they appear and vanish all the time. Scientists predicted the existence of virtual particles some 80 years ago, but we have never had experimental evidence of this process until now.”