Light is everywhere,it illuminates our world, enables vision, and travels across galaxies. But what is light, really? Is it a wave or a particle? The answer is both,and neither, depending on how ...

Does light behave more like a particle, or like a wave? Today we know the surprising answer. Here's why it took so long to get there.

Is light a wave or a particle? Well, it's not a particle. The photoelectric effect can be explained with a wave model for light and a quantum model for matter.

In fact it can even be in infinitely many places at the same time, exactly as a wave. Hence the notion of wave-particle duality, which is fundamental to all quantum systems.

For the first time, physicists have captured light acting as both a wave and a particle in the same snapshot.

The wave function is a mathematical description of the external attributes of a particle: its position, momentum, and rotational characteristics.

Like all other subatomic particles, photons exhibit wave-particle duality, meaning that sometimes they behave as tiny particles and sometimes they act as waves.

In the traditional formulation of quantum mechanics, when a particle is measured -- meaning it is found to be in one particular location -- the wave function is said to collapse.

Experimental confirmation of wave-particle duality. Complementarity relation of wave-particle duality is analyzed quantitatively with entangled photons as path detectors.