Acclaimed theoretical physicist and futurist Dr. Michio Kaku is designing a garment to make the wearer almost completely invisible, like Harry Potter. This is possible by making the light bend around an object instead of passing through it. Until a few years ago, most physicists thought that invisibility was an impossible violation of the laws of optics, but it turns out they were wrong...and it's much easier than anyone thought. In 2006, a team at Duke University demonstrated how substances called metamaterials, with refractive indices different from anything found in nature, could deflect beams of light.
The catch? If light bends around an object such as an invisibility suit, it is impossible to see out of it. Complete invisibility would render the invisible man completely blind. Kaku's solution is to use a beamsplitter to redirect a very small percentage (perhaps 4%) of the light into the invisible man's eye. Careful observers would be able to see the faint image of two eyes floating in the air, but that would be the only visual clue of the invisible person's presence.
Dr. Kaku believes that something resembling Harry Potter's invisibility cloak will be a reality in a few decades. I was skeptical that progress could be made that quickly, until I saw the current state of progress in this field. Skip to 3:40 in the first clip to be amazed.
While an invisibility cloak would certainly be impressive from a technical standpoint, I'm not sure it would actually be a good development for society. I can think of a lot of pernicious uses for an invisibility cloak, but very few positive applications. This is an invention that may end up being banned, and/or limited to military/intelligence agencies.
By 2040 - An "invisibility suit" exists which renders the wearer almost completely invisible to those who aren't actively looking for him or her.