Light Reading Light: Wave and Particle

March 05, 2015

Research scientists have achieved the first ever pictorial evidence that light can simultaneously behave as a particle and as a wave.

The concept of photons -- that is, particles of light -- has been around since 1905, explained by Albert Einstein as the "photoelectric" effect. This effect occurs when light hits a metal surface, causing that metal surface to emit photoelectrons. However, the behaviour of these electrons could not be accounted for if the light was a wave -- it only made sense if the light was made up of particles.

It has been since demonstrated that light behaves as both. It has been observed behaving as a wave, and it has been observed behaving as a particle -- although it had never, until now, been directly observed doing both at the same time.

The achievement has been made by researchers at the École polytechnique fédérale de Lausanne, led by Fabrizio Carbone -- employing a novel technique that uses electrons to image light.

"This experiment demonstrates that, for the first time ever, we can film quantum mechanics -- and its paradoxical nature -- directly," Carbone said.