Matteo Calabrese

Thousands of universes were born in a computer, all to tell us about our own. Each one has its own galaxy clusters, arranged by the laws of gravity like peas in a jar shaken with varying force. From how the peas settle, you can tell what kind of hand shook the jar.

Light from the earliest epoch of the universe has been traveling toward us for billions of years. On its way, it passes by enormous galaxy clusters. Their gravity slightly bends this light, just as a shop window distorts the view of the street behind it. As clusters grow, the bending becomes more noticeable. This effect is known as the Rees-Sciama effect.