The next big thing in homeland-security technology is a T-ray machine, which can see through leather, fabric, cardboard and paper, but can't penetrate water or metal. T-rays (terahertz rays) used to be really hard to make without massive gear, but now researchers in Turkey and Japan have figured out how to build a compact T-ray machine using—what else?—high-temperature superconducting crystals. T-rays may prove to be the next great ray; they can even look half an inch into your skin and spot tooth decay in your mouth. And unlike X-rays, which do evil things to your cells, T-rays don't have the energy to cause cancerous cell ionization. They're totally harmless, except of course when used by TSA to look at you naked. [Reuters]