You might honestly swear you are up to no good if you got your hands on a new portable invisibility cloak designed by German scientists.
However, the new cloak, created by scientists at the Karlsruhe Institute of Technology in Germany, isn't exactly wearable (yet), but is one of the first portable cloaks of its kind and works without the need for any additional specialized equipment.
We already have invisibility cloaks, but they're not really cloaks, just systems that bend light around objects that keep them hidden. Most are very small and only work at certain wavelengths, which means they're not anything like the invisibility cloak we think of, such as the one worn by Harry Potter.
This new cloak, though, is different and can hide small objects from view, in a much more Harry Potter-like way.
So how does this new invisibility cloak actually work? It starts with bending light around an object, but that means the light now has to travel farther to do the same work, taking more time to get there. We can't really speed light up faster than its normal speed (at least according to general relativity), so that causes a problem.
The German researchers, though, designed their cloak to scatter light. This means that when light hits the material of the cloak, it slows down the speed of light through the material, so that the light that goes around the material travels at the same speed as that which goes through the material.
"Our cloak takes advantage of the much lower effective propagation speed in light-scattering media," says Robert Schittny, the lead scientists on the project. "As we seemingly slow down the light everywhere, speeding it up again in the cloak to make up for the longer path around the core is not a problem."
If that sounds like rocket science, it's not: it's just physics. However, the KIT team hope that their cloak will make it into classrooms (Hogwarts, anyone?) to inspire future scientists to take an interest in physics and perhaps even improve upon the cloak's design.
"It is a macroscopic cloak that you can look at with your bare eyes and hold in your hands," says Schittny. "With a reasonably strong flashlight in a not too bright room, it is very easy to demonstrate the cloaking. That means no fancy lab equipment, no microscopes, no post-processing of measurement data. The effect is just there for everyone to see."
[Photo Credit: Warner Brothers]