Invisibility: The History and Science of How Not to Be Seen

Gbur (Falling Felines and Fundamental Physics), a physics professor at the University of North Carolina, Charlotte, surveys in this entertaining primer the state of research into literal invisibility. Providing an overview of scientific theories on how to achieve invisibility, he explains that “passive invisibility” conceals objects by manipulating light to pass around them, while “active invisibility” involves producing new light to disguise the object. Among the fascinating examples Gbur cites of the latter is a crude invisibility cloak developed by Japanese professor Susumu Tachi that captures the scene behind the wearer with a camera and projects the image onto the cloak’s front, though the wearer remains visible from the sides. Passive invisibility poses its own problems; Gbur notes that using refraction to disguise an object would require the object to have about the same density as air. However, he suggests that research on the physics of invisibility has practical applications and contends that sea vessels could be designed to redirect ocean waves the same way that researchers hope to achieve invisibility by redirecting the electromagnetic waves that constitute light. Discussions of how relativity affects light and how light interacts with atoms can get technical, but there’s enough fun trivia to keep readers hooked. The result is a robust examination of a fascinating field of research. Photos. (Apr.)