### In the beginning was the bit

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science

From New Scientist, In the beginning was the bit:

"NOBODY understands quantum mechanics," lamented Richard Feynman. But Anton Zeilinger at the University of Vienna aims to prove him wrong. His research group has demonstrated the futuristic phenomena of quantum teleportation and quantum encryption, and these successes have encouraged Zeilinger to search for the essence of quantum mechanics--the irreducible kernel from which everything else flows. He believes that he has found it. If he is right, all the mysteries of the quantum world will turn out to be inescapable consequences of a single, simple idea.

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Zeilinger and Brukner...introduce a three-dimensional space they call information space. The relationship between 2D Hilbert space and 3D information space is a bit like the relationship between an accurate perspective drawing and a real, three-dimensional object. This new space is much closer to our reality, as its axes correspond to the answers of yes or no questions about an elementary system. An electron's spin can be measured, or quantised, along the x, y, or z axes of real space, which gives the three dimensions of information space a clear correspondence with reality. In other two-state systems the connections are not so obvious, but three independent propositions will always exhaust the possibilities.

Any quantum system has to describe how states change over time, so the point in information space has to move. It seemed natural to Zeilinger and Brukner to have the point move as if it were a real, classical object. So they used the mechanical equation that governs the motion of bullets and billiard balls. When translated back into its equivalent form in Hilbert space, it turns out to be none other than SchrÃ¶dinger's equation.

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