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"Action at a distance" quantum uncertainty

Albert Einstein Two things he did not like quantum theory were the inherent uncertainty and its assertion that the particles can remain strangely linked even when separated by great distances. The first was dismissed with the phrase "God does not play dice", and the second, which he called "spooky action at a distance."

a pair of physicists now say that these two odd effects are closely linked - and that uncertainty limits the "connected" to separate the particles can be.

When two particles are linked distant quantum mechanics, or entangled, are measured, the results are more similar than predicted by classical physics. "Nature is non-local," said Sandu Popescu, University of Bristol. "This is possibly the most important lesson of quantum theory."

But these non-local ties are not as influential as it possibly could be. Popescu and Daniel Rohrlich colleague, now at Ben Gurion University in Israel, estimated 15 years ago that the laws of physics could allow an even closer coordination between the systems remotely, what physicists wonder why the quantum theory goes so far as he could.

Jonathan Oppenheim, University of Cambridge in the UK and Stephanie Wehner, National University of Singapore indicate that they have found a clue. The secret, they suggest, is another famous property of the quantum world - its inherent uncertainty.

"Even Spookie '

In quantum theory, the states of a quantum system can not be defined precisely. The principle of uncertainty, for example, means that any effort to measure the position of an electron mean giving up precise knowledge of its speed, or vice versa.

Using information theory, a basic tool of computer quantifying the amount of information contained in any structure, and Wehner Oppenheim studied how the degree of uncertainty in a theory should influence the opportunities presented for local connections.

hypothetical theories that contains no uncertainty, found, could provide coordination between the systems remotely as strong as the limit calculated by Popescu and Rohrlich. "Quantum mechanics could be even Spookie" says Oppenheim. "But the Heisenberg uncertainty principle gets in the way."

The results do not indicate what mechanism uncertainty underlying physical join non-locality. But because the results rest only the ideas of information theory, should have, not only for quantum theory, but for any theory to conceive the future as well, say the authors.

"This is a very original and important," says Popescu. But he cautions that it is probably not the last word on why quantum theory is just not what is local. "This work is not intended to solve the problem," he says. "But going into a new direction", adding that other possible explanations that physicists have explored in recent years.