Wave-Particle Duality

Light is complicated as it can act as both a wave and as a particle.

A particle of light is known as a photon. These can be thought of as little packets of light, carrying energy. When we take a photograph on a modern camera, or on a telescope camera, we count these photons. The more we count the brighter an object is - we call this measurement the flux.

When light acts as a wave, it still carries energy, but it has a bunch of other information too. This helps us to understand more about it.

Every wave (e.g., light, water, or sound) has the following features:


What is Interferometry?

Interferometry is a technique used by scientists and engineers. Tools called interferometers add together 2 or more waves of light. When they do this, the waves of light interact (or interfere) with each other. This can add the waves together, making them brighter. It can also cancel the waves out. Interference only takes place if the waves come from the same object or have the same frequency. We call these types of wave coherent.


Scientists have 2 ways to think about light: it can be a wave or a particle called a photon. It took a long time to discover that both were true. For some time there had been a debate between supporters of each point of view. Nobody - or everybody - won the argument; light is both wave and particle.