Question

Is light really a wave, a ray or a stream of particles ?

Answer 1

The answer is that in some situation light acts as particles and in others it acts as wave

This fundamental question has dogged scientists for decades, because light seems to be both. However, until now, experiments have revealed light to act either like a particle, or a wave, but never the two at once.

researchers have devised a new type of measurement apparatus that can detect both particle and wave-like behavior at the same time. The device relies on a strange quantum effect called quantum nonlocality, a counter-intuitive notion that boils down to the idea that the same particle can exist in two locations at once.

"The measurement apparatus detected strong nonlocality, which certified that the photon behaved simultaneously as a wave and a particle in our experiment," physicist Alberto Peruzzo of England's University of Bristol said in a statement. "This represents a strong refutation of models in which the photon is either a wave or a particle."