Something from nothing is a quantum possibility

An increased understanding of the subatomic world has turned conventional wisdom inside out, furthering the case that the law of energy conservation is simply a conceit and its violation a catalyst for an astonishing new idea

erner Heisenberg's Uncertainty Principle opened the doors to overturning the law of energy conservation.

Is it ever possible to get something for nothing? The global wave of financial scandals has been widely seen as confirmation that "only nothing can come from nothing", as the Greek philosopher Parmenides argued around 2,500 years ago and finger-wagging moralists have been telling us ever since. Slackers everywhere should therefore take heart from the mounting evidence that Parmenides and his ilk could not have been more wrong. It is now becoming clear that everything can - and probably did - come from nothing.

Whenever some common-sense view of the nature of reality is challenged like this, you can bet quantum theory will be involved. And so it proves in this case, with two recent advances in the understanding of the subatomic world adding to the weight of evidence. Unlike financial scam artists, physicists have been amassing evidence for their unlikely claim for decades, beginning with the discovery by a young German theoretician of a loophole in a supposedly inviolable law of nature.

As countless generations of schoolchildren are taught to parrot in class, the law of conservation of energy states that it cannot be created or destroyed, but merely transformed from one form to another. In 1927, Dr Werner Heisenberg showed that the truth is rather more interesting in a paper that addressed a philosophical question: how do we know what reality is like? The answer seems obvious: by making observations. But Dr Heisenberg pointed out that the newly emerging quantum theory implied that the very act of observation affects whatever is being observed. That, in turn, means it is impossible to know with total precision what reality is actually like.

Dr Heisenberg went on to show that his now-celebrated Uncertainty Principle implies there is always some uncertainty about properties of any region of space - specifically, how much energy it contains over a given period. The "law" of energy conservation is thus merely a conceit, and one whose violation leads to some astonishing consequences - including support for the something-for-nothing view of reality.

Heisenberg's principle implies, for example, that the very space around us is seething with subatomic particles, popping in and out of empty space. During their fleeting existence, these "vacuum particles" interact with each other, and turn the supposedly dull vacuum of space into the quantum vacuum - which astronomers now know is anything but dull. Observations suggest the expansion of the entire cosmos is being propelled by quantum vacuum energy, in the form of enigmatic "dark energy".

Something for nothing can also be seen working its magic down at the other scale of things. In the late 1940s, the Dutch physicist Hendrik Casimir predicted that the quantum vacuum could generate a force-field between two flat plates of metal. This "Casimir Effect" again emerges literally out of nowhere, pushing the plates together. The force is pretty feeble: between two book-sized plates separated by just a hair's breadth, it is equivalent to barely the weight of the ink in this sentence's full stop, and it was properly measured only in the mid-1990s. Even so, it's enough to cause the components of delicate micro-mechanical devices to seize up.

Fortunately, back in the 1960s some Soviet theorists predicted that the quantum vacuum can be engineered so that the Casimir force becomes one of repulsion rather than attraction. And last week a team of scientists in the US reported in the journal Nature that they had confirmed the prediction in dramatic style, using the repulsive form of the force to levitate a gold-plated ball. OK, the ball was less than the size of a full stop, but that's pretty impressive considering it was being held aloft by nothing but the energy of empty space.

Some theorists now think they can go even further, and use the physics of something for nothing to explain the origin of literally everything. They claim that the Big Bang from which the entire universe emerged was the result of convulsions in the quantum vacuum which took place around 14 billion years ago. New theoretical work on the nature of matter suggests we may now have to regard even ourselves to be manifestations of the quantum vacuum.

All atoms are made up of electrons plus a far more massive central nucleus, made up of clusters of particles called quarks. It seems obvious that the mass of the nucleus must be the sum total of the masses of its quarks - but that reckons without the effect of the quantum vacuum. It turns out that the quarks account for only a tiny fraction of the total mass of a nucleus. By far the bulk comes from the subatomic "glue" that binds its quarks together. And this glue takes the form of vacuum particles flitting in and out of existence.

That at least is the theory. Confirming it requires some appallingly difficult calculations, involving all the different manifestations of quantum vacuum particles inside the nucleus - of which there are trillions. At the John von Neumann Institute for Computing in Jülich, Germany, Dr Stephan Dürr and colleagues have had a shot at doing this titanic calculation, using a computer capable of performing over 100 million million calculations a second.

After several months of number-crunching, the machine has now spat out its estimate for the mass of a hydrogen nucleus, and it is within 2 per cent of the value measured in the lab. In other words, virtually all the mass contained in atoms - and indeed us - appears to be nothing more than the evanescent energy of empty space. It thus seems that much as we may like to distance ourselves from financial scam artists and get-rich-quick schemes, we are all living proof that it's possible to get something for nothing.

Robert Matthews is Visiting Reader in Science at Aston University, Birmingham, England