What do we hear when we change the direction of a wire?

«Genz met Alson Kelen and Korent Joel in Majuro in 2005, when Genz was 28. A soft-spoken, freckled Wisconsinite and former Peace Corps volunteer who grew up sailing with his father, Genz was then studying for a doctorate in anthropology at the University of Hawaii. His adviser there, Ben Finney, was an anthropologist who helped lead the voyage of Hokulea, a replica Polynesian sailing canoe, from Hawaii to Tahiti and back in 1976; the success of the trip, which involved no modern instrumentation and was meant to prove the efficacy of indigenous ships and navigational methods, stirred a resurgence of native Hawaiian language, music, hula and crafts. Joel and Kelen dreamed of a similar revival for Marshallese sailing — the only way, they figured, for wave-piloting to endure — and contacted Finney for guidance. But Finney was nearing retirement, so he suggested that Genz go in his stead. With their chief’s blessing, Joel and Kelen offered Genz rare access, with one provision: He would not learn wave-piloting himself; he would simply document Kelen’s training.

Joel immediately asked Genz to bring scientists to the Marshalls who could help Joel understand the mechanics of the waves he knew only by feel — especially one called di lep, or backbone, the foundation of wave-piloting, which (in ri-meto lore) ran between atolls like a road. Joel’s grandfather had taught him to feel the di lep at the Rongelap reef: He would lie on his back in a canoe, blindfolded, while the old man dragged him around the coral, letting him experience how it changed the movement of the waves.

But when Joel took Genz out in the Pacific on borrowed yachts and told him they were encountering the di lep, he couldn’t feel it. Kelen said he couldn’t, either. When oceanographers from the University of Hawaii came to look for it, their equipment failed to detect it. The idea of a wave-road between islands, they told Genz, made no sense.

Privately, Genz began to fear that the di lep was imaginary, that wave-piloting was already extinct. On one research trip in 2006, when Korent Joel went below deck to take a nap, Genz changed the yacht’s course. When Joel awoke, Genz kept Joel away from the GPS device, and to the relief of them both, Joel directed the boat toward land. Later, he also passed his ri-meto test, judged by his chief, with Genz and Kelen crewing.

Worlds away, Huth, a worrier by nature, had become convinced that preserving mankind’s ability to way-find without technology was not just an abstract mental exercise but also a matter of life and death. In 2003, while kayaking alone in Nantucket Sound, fog descended, and Huth — spring-loaded and boyish, with a near-photographic memory — found his way home using local landmarks, the wind and the direction of the swells. Later, he learned that two young undergraduates, out paddling in the same fog, had become disoriented and drowned. This prompted him to begin teaching a class on primitive navigation techniques. When Huth met Genz at an academic conference in 2012 and described the methodology of his search for the Higgs boson and dark energy — subtracting dominant wave signals from a field, until a much subtler signal appears underneath — Genz told him about the di lep, and it captured Huth’s imagination. If it was real, and if it really ran back and forth between islands, its behavior was unknown to physics and would require a supercomputer to model. That a person might be able to sense it bodily amid the cacophony generated by other ocean phenomena was astonishing.

Huth began creating possible di lep simulations in his free time and recruited van Vledder’s help. Initially, the most puzzling detail of Genz’s translation of Joel’s description was his claim that the di lep connected each atoll and island to all 33 others. That would yield 561 paths, far too many for even the most adept wave pilot to memorize. Most of what we know about ocean waves and currents — including what will happen to coastlines as climate change leads to higher sea levels (of special concern to the low-lying Netherlands and Marshall Islands) — comes from models that use global wind and bathymetry data to simulate what wave patterns probably look like at a given place and time. Our understanding of wave mechanics, on which those models are based, is wildly incomplete. To improve them, experts must constantly check their assumptions with measurements and observations. Perhaps, Huth and van Vledder thought, there were di leps in every ocean, invisible roads that no one was seeing because they didn’t know to look.... »