When Harry Potter didn't want anyone to see him, all he had to do was pull on a magical cloak and -- poof! -- he was invisible. Although invisibility cloaks, which work by bending light around an object have been around since 2006, scientists said in June that they made a major breakthrough by building a broadband device that can hide objects at a wide range of light frequencies [source: MIT]. Of course, there was just one teeny drawback: The device made other parts of the object more noticeable.
Here's how: While a person might not be able to see an object at one point in the light spectrum, it makes another part of the object more visible. For example, the cloak might make an object invisible in the red light spectrum, but if it was illuminated by white light, which contains all colors, that object would become bright blue and stand out like a sore thumb. In other words, it's impossible to become fully invisible. The device could be used in biomedicine and in the military [source: Pocklington].