In ancient Greece,Plato tried to think an talk his way to the truth in extended dialogues with his disciples.Today physicists such as Leonard Mandel of the University of Rochester operate in a somewhat different fashion.He and his students,who are more likely to wear t-shirts and laser proof goggles than robes and sandals,spend countless hours bent over a large metal table trying to align a laser with a complex network of mirrors,lenses, beam splitters and light detectors.

Plato

Yet the questions they address in their equipment-jammed laboratory are no less profound than those contemplated by Plato in his grassy glade.What are the limits of human knowledge? Is the physical world shaped in some sense by our perception of it? Is there an element of randomness in the universe,or are all events predetermined?