(Image: Matthew Richardson)
IT DEPENDS what you mean by nothing. Ask a physicist about a vacuum, the very definition of nothingness for most of us, and they will tell you it is pulsing with activity. According to quantum theory, in a vacuum wave-like fields are constantly fluctuating, producing particles and their antimatter equivalents that fizzle in and out of existence. So even in the depths of interstellar space, there is plenty going on in what we call zilch.
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This idea leads to some outlandish predictions. In 1948, the physicist Hendrik Casimir proposed that if you place two parallel metal plates close to each other in a vacuum, there will be more quantum electromagnetic fluctuations either side of the plates than between them. Their proximity limits the wavelength of fluctuations in that space, creating a force pushing the plates together. The phenomenon became known as the Casimir effect.
It鈥檚 a weakling force but it has been detected. And more recently, physicists like , now at the University of Waterloo in Canada, have tried to prove another eccentric prediction: that it is possible to use the effect to release latent energy. Instead of allowing the fluctuations to tug on the plates, you rapidly force the plates together to squeeze their wavelengths 鈥� and force out photons (see diagram).
Trouble is, you can鈥檛 accelerate even the tiniest mirror to the huge speeds required. So in 2011 Wilson and his colleagues tested the dynamical Casimir effect, as it鈥檚 known, by using rapidly changing electrical currents to simulate the effect of minuscule mirrors whooshing together at a quarter of the speed of light.
Sure enough, 鈥� energy, albeit a piffling amount, from thin air. 鈥淵ou can think of it as being like the mirror has knocked the particle into existence,鈥� says Wilson.
The experiment didn鈥檛 produce energy overall: generating the currents required more than was produced. But harnessing the Casimir effect remains theoretically possible 鈥� and even a small success might go a long way.
Engineering the inside surfaces of the mirrors to manipulate fluctuating fields in a different way can create an outward pressure that pushes two objects apart. This reverse Casimir effect could come in handy when making switches for nanoscale devices. For now though, the build-up of electric charge between moving parts swamps the effect. And that鈥檚 the least of the caveats. Some physicists still refuse to believe that quantum fluctuations in a vacuum are real, never mind the Casimir effect and its reversal.
Wilson is now refining his experiments to answer the criticism that he simply produced heat energy, a result of the apparatus warming up. And if he can show that the particles generated are entangled, as predicted by Casimir, that would provide the most convincing evidence yet that you really can get something from nothing.
Read more: 鈥�10 mysteries that physics can鈥檛 answer鈥� yet鈥�
This article appeared in print under the headline 鈥淐an we get energy from nothing?鈥�
