Moving mirrors make virtual light real

Nature : One of the most important tenets of quantum mechanics, writes Geoff Brumfiel for Nature, is the principle that empty space is not empty at all. Vacuum contains particles coming in and out of existence, some so quickly that they’re described as virtual. They can have tangible effects regardless of the brevity of their presence.Theoretically, a mirror moving through a vacuum at nearly the speed of light can convert virtual photons into observable real photons. Per Delsing of Chalmers University of Technology in Sweden and colleagues used a piece of quantum electronics known as a superconducting quantum interference device (SQUID) to make a superconducting circuit in which the SQUID acted as a mirror.When they passed a magnetic field through the SQUID, it moved slightly, and when they switched the direction of the magnetic field back and forth several billion times a second, the SQUID moved back and forth in response, at about 5% the speed of light, and produced a shower of observable microwave photons. If the findings are verified, they would be one of the most unusual experimental proofs of quantum mechanics in recent years.