Scientists in China were able to make a "false wall" in an incredible demonstration of illusion optics. Find out why you shouldn't believe your eyes anymore, thanks to physics.
China has been in the business of building walls for a long, long time. Recently, they've added a new twist on an old plan. Instead of going to all the trouble of building a wall, they're not building a wall and making people think they had. The wall, in this case, is pretty small. Most people wouldn't notice the entire construction site. However, it's the first time such a thing has been done, and so even if the wall is tiny, it's remarkable.
The false wall is constructed leaving a small gap in a physical barrier. The gap is lined by two conductors in close proximity. One of those conductors is covered by a slab of meta-material that ‘bounces back' electromagnetic radiation. Because of this "bounce back" electrons build up on the surface of the material, thicker and thicker.
When light (or in the case of the experiment, radio waves) comes plowing into the gap between the conductors, it cannot pass through the electrons. It rebounds, just as it would from a conventional wall. Although the experiment was done using radio waves, if it were done using photons a person looking at it would see an unbroken barrier.
Everyone involved with the project admits it's a baby step. Technology to make it applicable to human-sized walls is several decades away. Still, it's an important first step. This isn't a hologram or a projection. It's not a way to trick the eye, or the way the brain processes images. It's a way to manipulate incoming electromagnetic waves into not ‘seeing' a gap in a physical barrier. That's something new.