From the checkout scanner to eye surgery to the internet itself, lasers are woven through modern life — yet most of us have no idea what makes laser light different from the light of a torch. This episode explains the surprisingly elegant physics of light marching in perfect step.

You'll come away understanding what makes a laser beam so pure and tight, the quantum trick called stimulated emission that Einstein predicted, and why this one invention quietly runs so much of the modern world.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: Britannica – "Laser"; American Physical Society – "This Month in Physics History: Maiman builds first laser"; *The Feynman Lectures on Physics*, Vol. I.