Xi-Cheng Zhang has worked for nearly a decade to solve a scientific puzzle that many in the research community believed to be impossible: producing terahertz waves—a form of electromagnetic radiation in the far infrared frequency range—from liquid water. Now, as reported in a paper published in Applied Physics Letters, researchers at the University of Rochester have "made the impossible, possible," says Zhang, the M. Parker Givens Professor of Optics. "Figuring out how to generate terahertz waves from liquid water is a fundamental breakthrough because water is such an important element in the human body and on Earth." Terahertz waves have...