'Quantum friction' slows water flow through carbon nanotubes, resolving long-standing fluid dynamics mystery

For 15 years, scientists have been baffled by the mysterious way water flows through the tiny passages of carbon nanotubes—pipes with walls that can be just one atom thick. The streams have confounded all theories of fluid dynamics; paradoxically, fluid passes more easily through narrower nanotubes, and in all nanotubes it moves with almost no friction. What friction there is has also defied explanation.