Thermometers can do a great deal of things: measure the temperature at the focal point of your impeccably braised chicken, or let you know whether to keep your kid home from school because of sickness. But because of their size, conventional thermometers' purposes are as yet restricted. "How would you painlessly measure a temperature inside a living framework like a human?" said NIST's Thinh Bui. "Or, on the other hand, in different conditions that might be difficult to get to—say, the temperature inside a Kevlar vest as a shot enters it. How would you approach that? You can't put a