Migrating birds make some extraordinary journeys—up to 40,000 miles round trip, in the case of the arctic tern. How do they know where they’re going on such a long flight? They don’t have satellite directions, but they may in fact have a more efficient global positioning system: the earth’s magnetic fields. There are specialized compounds in the eyes, brains, and even the bills of migrating birds that help them sense those invisible forces, giving them a built in compass. Not only that, scientists have recently hypothesized that these birds take advantage of “quantum entanglement,” an effect where molecules are mysterious linked together, no matter how far apart they are. Specifically, they are studying a molecule in avian eyes called cryptochrome. It’s possible that the quantum entanglement of that molecule may allow birds to actually see earth’s magnetic fields in color, giving them intangible landmarks by which to navigate, and making a true “bird’s eye view” something that we humans may never comprehend.