MIRROR PHYSICS

Reflect on the science of light bouncing off smooth and shiny surfaces

- AILSA HARVEY

The first mirrors date to around 6,000 BCE, but people have used reflections in natural features such as puddles for many thousands of years. When you look into a mirror, the reflection looking back at you is a life-size, exact visual copy. The angle at which you face the mirror determines what reflection you see - just as if you were to throw a ball at a wall, the angle at which it returns is equal to the angle it hits the wall at. Because the sides of an object line up exactly with the sides of the reflected image, the mirror image is a horizontally flipped version of reality. Your brain interprets the mirror image of you as another person who has turned to face towards you. When you lift your left arm, for example, it appears as if the mirror image of you is raising their right.

Light only behaves in this way when it interacts with a smooth, reflective surface.