Creating Light From a Vacuum
November 18, 2011 Leave a comment
Quantum theory predicts that in a vacuum, virtual particles are constantly being created in pairs and then quickly destroying each other. Up until now, outside of theory there hasn’t been any proof that they actually exist. Now, researchers have managed to make some of these particles materialize: by giving energy to virtual photons, they created “real”, measurable photons. Did they say “Let there be light!” as they did it? Let’s just pretend so.
Chalmers scientist, Christopher Wilson and his co-workers have succeeded in getting photons to leave their virtual state and become real photons, i.e. measurable light. The physicist Moore predicted way back in 1970 that this should happen if the virtual photons are allowed to bounce off a mirror that is moving at a speed that is almost as high as the speed of light. The phenomenon, known as the dynamical Casimir effect, has now been observed for the first time in a brilliant experiment conducted by the Chalmers scientists.
“Since it’s not possible to get a mirror to move fast enough, we’ve developed another method for achieving the same effect,” explains Per Delsing, Professor of Experimental Physics at Chalmers…
The “mirror” consists of a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. By changing the direction of the magnetic field several billions of times a second the scientists were able to make the “mirror” vibrate at a speed of up to 25 percent of 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,” says Per Delsing. “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.”
What happens during the experiment is that the “mirror” transfers some of its kinetic energy to virtual photons, which helps them to materialise. According to quantum mechanics, there are many different types of virtual particles in vacuum, as mentioned earlier. Göran Johansson, Associate Professor of Theoretical Physics, explains that the reason why photons appear in the experiment is that they lack mass.
“Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy.”
That’s crazy. What’s the wear and tear like on something vibrating at 25% the speed of light? It’s unimaginable. Whoever engineered that must’ve had an incredibly difficult time.
I was torn about posting this article since on the one hand it sounds awesome, but on the other hand it’s definitely over my head, so I can’t exactly help break it down for you any more than they already did. Anyway, it’s clear at least that this is a very cool experiment and very big news for physics, so let’s bask in this moment of awesome. Are you basking? Bask!