The Duality of Light

by: Noah, Michael


Light is all around us and is what allows us to see. Light travels extremely fast. The speed of light is 299,792,458 m/s. Light isn't just extremely fast and important to our everyday lives, it has strange and interesting properties. Light exists in our universe as both a wave and a particle.

Light as a Particle

Light as a particle is known as a photon. Photons are in a way just like any other particle we are familiar with. They can be locked by solid objects and when shot through a double slit, they go through either the left or the right slit and produce a seemingly random pattern. Light's existence as a particle is how light travels through space. If light were only a wave and had no medium to travel through, it wouldn't be able to travel through space as space is generally regarded as a vacuum. The difference though is that light isn't a normal particle. Each photon has its own frequency as if each photon was its own individual wave packet. Photons don't have mass either, but can have momentum.

Light as a Wave

Light as a wave works pretty much like any other wave would. Light waves experience the Doppler effect, light waves follow the law of wave reflection, and they create an interference patter when two waves collide with each other. As an object accelerates away from another object, Light given off or reflected looks more red and vice versa due to the light waves have increased wavelengths. This is the Doppler effect with light. The law of wave reflection states that the angle that a wave approaches a flat surface is equal to the angle it leaves the surface after bouncing off it. Last but not least when light waves interact with each other, constructive and destructive interference takes place to form a light and dark pattern.