Basically, because the wavelength of T-rays is so short (less than a millimeter), the rays can provide much higher resolution than, say,conventional radar, which uses frequencies with wavelengths measuring anywhere from a few centimeters to 100 meters. The density of T-rays makes them good for carrying large amounts of data, too—and, as an added bonus, they’re good at safely penetrating a few millimeters of skin. (Yes, airports are interested in terahertz security scanners.)