Alan Epstein has crafted micro gas-turbine engines out of silicon that he says could become a powerful alternative to the standard rechargeable battery for portable devices. The tiny gas turbines are a little smaller than a dime, spin at more than a million revolutions per minute, and can run on a container of diesel fuel that about the size of a D battery. The US military is already interested in the new technology for mobile soldiers, as they currently lug around some pretty big battery packs. As the technology advances, Epstein is confident that cell phones, PDAs, laptops, and other portable electronics could be fitted with the little jet engines as a more efficient alternative to current battery technologies. One problem, of course, is that you would end up with a cellphone that has an exhaust. "Ooh, excuse me. No, no, that was my cellphone. Really. Ahem."