Everything that humans have seen up until now exists in the 4.9 per cent of the universe that interacts with light. The rest is hidden from view. Most of it, physicists believe—68.3 per cent—is dark energy, an enigmatic force that drives the accelerating expansion of the cosmos. The rest—26.8 per cent—consists of dark matter, a ghostly goo that is thought to hold the cosmos together.
Read more from frequent Director's Visitor Siobhan Roberts about the physicists, among them Professor Nima Arkani-Hamed and former Member Tracy Slatyer, contributing to the hunt for dark matter at the New Yorker.