If you believe the world’s leading physicists, the vast majority of matter in the universe is hiding in plain sight. For nearly a century, evidence has mounted that the gravitational pull necessary to keep clusters of galaxies intact, as well as stars within galaxies from flying apart, requires far more matter than we can see—matter, according to the experts, that has eluded our telescopes, because it does not give off light. Problem is, such “dark matter” has also eluded one specially designed detector after another that researchers have deployed to catch it. Which raises the big question: What if we have failed to find dark matter because it isn’t there? Join leading physicists on a scientific treasure hunt that has proved more challenging than anyone expected, and may ultimately require rethinking some of our most fundamental ideas about the universe.

The Big Ideas Series is supported in part by the John Templeton Foundation.