Slathering yourself with mud to avoid head-hunting aliens is great and all, but it ain't exactly the paragon of good personal hygiene. Fortunately, researchers have concocted a cleaner and less cakey defense against Predators that's more likely to be mom approved. Fresh on the heels of the microwave invisibility project at the University of Texas at Austin, French researchers have found a way to make a cloak that can hide a subject from thermal imaging devices. The concept uses alternating materials with varying rates of diffusion to move heat around and create a thermally invisible region. Conversely, the technique can be used to concent
