T-RAYS CAN SENSE WHAT EVEN X-RAYS MIGHT MISS.

Terahertz radiation is the final frontier in the electromagnetic spectrum. It lies between microwaves and infrared light, with frequencies of around 1 trillion cycles per second. Worldwide, only a handful of laboratories were exploring terahertz light, or T-rays, before September 11. Since then, research has shifted into high gear. Compared with X-rays, T-rays promise sharper, more detailed views of what's inside luggage or hidden under clothing. Hit with a terahertz beam, molecules in explosives give off a distinctive optical signature. The same is true for cancer cells, illicit drugs, and most other substances. And T-rays don't seem to damage living tissue, so they could make for safer mammograms and dental exams.