Seeing Light

It is one of the most fascinating and perplexing quirks of physics - that light exists both as waves and as particles at the same time.

This seemed like a preposterous idea when Einstein proposed it a century ago, but many experiments since have confirmed this Nobel Prize winning insight to be true.

For all the work studying the wave-like and particle-like existence of light, scientists have never been able to find a way to observe both at the same time.

But now Swiss scientists at EPFL (Swiss Federal Institute of Technology in Lausanne) have come up with a way to see the dual nature of light. Their work was recently published in Nature Communications.

The experiment makes use of how electrons interact with light. A pulse of light was projected onto a tiny metallic wire only a few nanometres in size, where it was trapped there as a standing wave (a wave that doesn't change position over time). A steam of electrons was then directed close by the wire, so close that the electrons and the photons interacted. The exchange of energy along the wire was observed, with this data being used to create an image that showed for the first time both the particle and wave behaviour of light.

Image Credit - Fabrizio Carbone / EPFL