Why does light exist?

Light is one aspect of the Universe that, for most people, holds a deep and noticeable value in everyday life, helping them to navigate, learn from, and connect with the world around them. Yet it’s not particularly difficult to imagine life without it. After all, many nonhuman animals live in lightless environments. However, as Gideon Koekoek, an associate professor of physics in the research group Gravitational Waves and Fundamental Physics at Maastricht University, discusses in this lecture at the Royal Institution in London from April 2025, such a reality would be impossible. Koekoek pairs an exploration of fundamental physics with a series of experiments, making fascinating connections that build towards the conclusion that light in our Universe occurred not by chance, but through inevitability.