Richard Feynman, a revered physicist, Nobel prize-winner and all-around trouble-maker once said, "Nobody understands quantum mechanics." When the perhaps most brilliant quantum theoretician in the world admits this about his life's work, you know the field is strange! Two of the most puzzling consequences of quantum mechanics are the uncertainty principle and zero-point energy. Taking advantage of these weird conclusions, physicists have carried out an experiment in which they claim to produce light out of what we perceive to be empty space.
The uncertainty principle is a law of the universe that keeps you from knowing exactly where something is and exactly where it is going at the same time. The surer you are about one of these things, the less sure you are about the other. Carried to its logical extreme, this means that anywhere you look there is a (very) small chance that something may randomly be there.
How much energy would you expect to find in the vacuum, in empty space? The intuitive answer would be none! Because of the uncertainty principle however, there is always a small likelihood that there may be something in any area of supposedly empty space. No matter how empty you think it is, there is always some probability of something being there and having energy. This possible energy is known as zero-point energy.
In their research published this month, physicists in Sweden used a pair of mirrors facing one another to produce light from the vacuum between them. By moving the mirrors, they changed the nature of what can randomly appear in the empty space in the middle. When light appears, a process known as the dynamical Casimir effect, it is stuck bouncing between the two mirrors and detected.
The trick to this measurement is that the mirrors have to move very fast -- close to the speed of light -- to create enough light to be measured. Moving anything close to the speed of light is nearly impossible. To avoid this difficulty, a superconducting circuit was designed to work just like a mirror whose reflecting abilities can be changed extremely rapidly. These circuits, based off of a SQUID (superconducting quantum interference device) can be manipulated cleverly to mimic the near light speed mirrors.
Despite this news, keep in mind that when you hear a claim that something is powered by zero-point energy, it is certain to be a complete fraud! No one has ever found any possible way to harvest energy from it. However, seeing another counterintuitive quantum mechanics prediction come true is exciting for physicists and those like Mr. Feynman who seek to understand our strange universe.
Tom Hartsfield is a physics graduate student at the University of Texas.