Wednesday, 18 June 2008

Zeilinger and Quantum Mechanics

When I listen to good jazz I am temporarily willing to suspend my disbelief in the soul. And the Abram Wilson quartet are good enough not only to have me believe in the soul but to make it get up and dance. Check them out if you like New Orleans swing with a modern twist and trumpet playing that will blow your mind.

I was listening to them at the unlikely venue of the Institute of Physics in London. They were performing as part of a celebration of the first presentation of the Newton Medal, the IoP's new premiere award to any international scientist. The recipient was Anton Zeilinger who has worked on the fundamentals of quantum mechanics in a very productive life. His group in Vienna have made real such dream (thought) experiments as quantum teleportation, quantum cryptography and diffraction of large molecules (azobenzene, 3.2nm long for example).

The talk Zeilinger gave, preceding the concert, was clear and challenging and much of it hinged on the perceived opposite views of Einstein and Bohr. For Einstein the world was real and quantum mechanics had to reflect that - no spooky action at a distance. For Bohr physics was about what could be measured. Einstein "Are you really asserting that when no-one looks at the moon, it isn't there?". Bohr "Can you prove the contrary?".

That quantum mechanics can distinguish between these cases experimentally (so-called Bell's Inequality experiments) is a true wonder: philosophy once again has to stand aside as physics barges in and answers questions pondered for thousands of years.

Zeilinger's work is peppered with humour - subtle and sly in most cases. To demonstrate quantum cryptography they chose to transmit an image of the Venus Von Willendorf because, as he put it, it was one of the few images that was distinctly Austrian but nothing to do with war! A cryptographic message across the border to Slovenia on its accession to the EU in 2004 read simply "Welcome back!", a jibe at the country's recent communist past but Austro-Hungarian roots.

Zeilinger reminder us most of all that the pursuit of science is a deeply human act, driven by curiosity and personalities. Long may such strong personalities have their say!

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