Quantum theory’s prediction that the vacuum of space is full of virtual particles fluctuating in and out of existence has been proven true, according to findings published in Nature on Nov. 17.
Known as the dynamical Casimir effect, physicist Gerald Moore suggested back in 1970 that virtual photons would become real light particles if reflected off a mirror moving close to the speed of light.
In an innovative experiment, an international team of scientists replicated this relativistic mirror effect, providing kinetic energy to virtual particles to help them materialize.
“Since it’s not possible to get a mirror to move fast enough, we’ve developed another method for achieving the same effect,” said study co-author Per Delsing at Sweden’s Chalmers University of Technology in a press release.
“Instead of varying the physical distance to a mirror, we’ve varied the electrical distance to an electrical short circuit that acts as a mirror for microwaves.”
The researchers used a quantum electronic component called a SQUID (Superconducting quantum interference device), which is highly sensitive to magnetic fields. Its magnetic field direction can be changed several billions of times per second to create a “mirror” vibrating at up to 25 percent the speed of light.
“The result was that photons appeared in pairs from the vacuum, which we were able to measure in the form of microwave radiation,” Delsing explained.
“We were also able to establish that the radiation had precisely the same properties that quantum theory says it should have when photons appear in pairs in this way.”
According to quantum mechanics, there are a variety of virtual particles in vacuum. The photons appear in the experiment because they lack mass.
“Relatively little energy is therefore required in order to excite them out of their virtual state,” explained co-author Göran Johansson at Chalmers in the release.
“In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy.”
This research is important because it furthers understanding of basic physical concepts like vacuum fluctuations, which may be linked with the force of dark energy that is behind the ever-accelerating expansion of our universe.
