A LIMITLESS amount of energy – more than is stored in all the coal mines, oil fields and nuclear weapons in the world – could be sitting inside your left nostril. Luckily, although NASA scientists are trying to exploit this power source, they have no plans to stick tubes up your nose. For this energy exists everywhere in the Universe, even in the vacuum of empty space. If physicists succeed in tapping it, they will generate power and propulsion from nothing at all.
The dream of obtaining infinite energy has a scientific basis thanks to a quirk of quantum theory. Heisenberg’s famous uncertainty principle implies that at every point in space, even in the deepest vacuum, particles constantly appear and disappear, blinking in and out of existence like tiny Cheshire cats. Though they are mostly invisible and undetectable, these evanescent “virtual” particles have energy and momentum. They can even push objects – an effect first predicted back in 1948 by Dutch physicist Hendrik Casimir. According to quantum theory, each virtual particle has a wavelength related to its energy. Casimir realised that if you place two conducting plates close together, only virtual particles of a certain wavelength will fit into the confined space. Just as a guitar string can only play a limited number of notes, so the plates only contain a limited set of wavelengths. However, the undiminished zoo of particles presses on the outside of the plates, and without the full complement on the inside, the plates are crushed together.
It’s not just speculation. In 1995, Steven Lamoreaux, a physicist who now works at Los Alamos National Laboratory, rigged a twist-sensing device to measure the force needed to keep two plates apart. The force he detected was small – less than one billionth of a Newton, which is about the weight of a single slice of an ant that’s been chopped into 30 000 pieces – but it was definitely there.
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But can you use this effect to extract energy from the particles? In theory it should be possible – the two plates generate heat when they smack together, and this heat could be turned into electricity. But the plates have to be prised apart again, which takes more energy than you extracted in the first place. Most scientists believe that this kills the idea of making a perpetual-motion machine that runs on vacuum energy. But some free-spirited physicists think differently.
One such is Harold Puthoff, director of the Institute for Advanced Studies at Austin, Texas, and famous 25 years ago for his work on psychic phenomena. He believes that one way round the dilemma is to replace the plates with plasmas. A plasma is a gas of charged particles, but it behaves just like a metal plate as far as the Casimir effect is concerned. A cylinder of plasma would be compressed by the virtual particles just as the Casimir plates are forced together, and would be heated up into the bargain. The trick, says Puthoff, is that when you have extracted this heat energy there is no need to pry the plasma apart. Plasma is much cheaper and easier to make than metal plates, so you could simply discard the leftover plasma “ash” and generate more energy with a fresh plasma. Puthoff tentatively claims to have obtained 30 times as much energy as he put in. “We’ve even got a patent,” he says. However, most scientists are sceptical.
Puthoff believes that an even more promising method would be to use hydrogen atoms in small cavities. This idea – far from the mainstream – centres around the question of what keeps electrons in an atom from crashing into the nucleus. It’s a puzzle because any charged particle orbiting round a nucleus ought to lose energy and eventually spiral into the centre. Most scientists believe this doesn’t happen in an atom because quantum theory states that electrons can only possess certain energies. So when electrons hit the lowest energy permitted they are stuck and cannot drop any further. But Puthoff argues that the vacuum energy is the key. He believes that electrons absorb enough energy from the vacuum to compensate for the amount they lose while orbiting. If this is right, reducing the local vacuum energy Casimir-style by confining the atom in a cavity should make the electron settle into a new orbit, closer to the nucleus. Puthoff says it should be possible to harvest the energy released as the electron sinks into its new state. Alas, he has not yet managed to create a working device from “shrunken” hydrogen.
While Puthoff is struggling to realise his dream of an infinite energy source from nothing, NASA is also keeping its eye on possible applications of the Casimir effect. In fact, the agency is doing everything short of leafing through science-fiction novels to try to find new ways to propel people beyond the Solar System. In February, the Marshall Space Flight Center in Huntsville, Alabama held a symposium where scientists debated the merits of warp drives and other far-out ideas.
BIg dreams
Marc Millis, head of the Breakthrough Propulsion Physics Laboratory at the NASA Lewis Research Center in Cleveland, suggested at the meeting that astronauts might harness the energy in the vacuum to push a spaceship just as mariners harnessed the wind to drive a frigate. “If there were any way to get asymmetric forces – where you get force in one direction and not the other – you’d get a propulsive force,” he says.
Unfortunately, the Casimir effect seems to be symmetric; both plates pull each other together, and the action of one has an equal and opposite effect on the other. But if there were some sort of quantum sail, a one-way mirror which reflected virtual particles on one side and let them pass unhindered through the other, vacuum energy could push the object along. It’s a thrilling idea, but Millis admits that nobody has a clue how to do it in practice. “There are no theories how to engineer the device,” he says sadly.
What’s more, nobody knows how much energy is there for the taking. The equations of quantum mechanics, interpreted strictly, imply that there is infinite energy at every point in space. But physicists argue about what this means in practice. Millis and Puthoff say there’s more energy in the space of a coffee cup than we could ever use. Others – Nobel laureate Steven Weinberg from the University of Texas at Austin, for instance – say that there’s no more than a gallon of petrol’s worth in the volume of the Earth. However much energy there is, extracting it in a sustainable way continues to defeat even its most enthusiastic proponents. At least for the time being, the ultimate free lunch – energy and propulsion from nothing – is tantalisingly out of reach.
