Sci-Fi geekdom should be amazed at this piece of news. An invisibility cloak is real and here already.
The "cloak" is made from two pieces of calcite crystal—a cheap, easily obtained mineral—stuck together in a certain configuration.
Calcite is highly anisotropic, which means that light coming from one side will exit at a different angle than light entering from another side. By using two different pieces of calcite, the researchers were able to bend light around a solid object placed between the crystals.
"Under the assembly there is a wedge-shaped gap," said MIT's George Barbastathis, who helped develop the new system. "The idea is that whatever you put under this gap, it looks from the outside like it is not there."
The new invisibility cloak still has its drawbacks: For one, it works best under green light. The researchers designed the cloak this way because the calcite can only be configured for a very narrow wavelength of light, and human eyes are most sensitive to green, Barbastathis said.
In addition, the cloaking effect works only if you look at the hidden object from a certain direction. Viewing the object from another angle will make it "reappear."
Also, the system can only cloak objects that fit under the mineral wedge, which in this case is just two millimeters tall. Still, a larger piece of calcite should be able to hide larger objects.
They are still working on it, but I'm sure in time, we will have real cloak of invisibility.