In the double-slit experiment, light waves intervene with one another – or do they?
RUSSELL KIGHTLEY/SCIENCE PHOTO LIBRARY
Light is each a wave and a particle – or so now we have thought for about a hundred years. Since the arrival of quantum physics, light has been understood to exhibit wave-particle duality. One half of this duality will be traced to physicist Thomas Young who, in 1801, carried out an experiment that confirmed light’s wave character: the double-slit experiment. But a radical new interpretation brings into query the outcomes of this well-known experiment, and certainly, the very nature of light itself.