How did the Vikings navigate the treacherous, fog-choked North Atlantic without a compass? In this episode, Albany Adams and Grace Shelly decode the legendary Viking Sunstone. We investigation the science of Iceland Spar (Calcite)—a crystal that can literally "see" through clouds by detecting the polarization of light.

But the story doesn't end in the 10th century. We're breaking down how the very same physics the Vikings used to find the sun is now being used by 2026 researchers to develop macroscopic invisibility cloaks. From the "Haidinger’s Brushes" in your own eye to the literal bending of reality, we’re looking at the ancient crystal that is still helping us see—and hide—the world today.