According to media reports on the 20th, invisibility cloaks only appeared in fantasy novel before. Now scientists are boldly trying to develop a real invisibility cloak. Of course, this invisibility cloak can't hide Captain James T Kirk's romulan spaceship or Harry Potter, but it is a significant start and paves the way for more advanced design.

In the first successful experiment, researchers from the United States and Britain hid a copper column.

The researchers said that the phenomenon in the experiment is like a mirage, and the heat causes the light to bend, hiding the road behind the image appearing in the sky. David Sherig, an associate researcher in the Department of Electronic and Computer Engineering at Dick University and a designer of invisibility cloaks, said: "We have made an artificial mirage, which can hide something so that observers can't see it from anywhere."

In the first attempt, the researchers designed a coat to stop the microwave of the detected object. Like light waves and radar waves, microwaves usually reflect back when they encounter objects, so instruments will find such objects and form detectable shadows. The invisibility cloak uses a special material, which allows radar waves, light or other waves to bypass objects without rebounding, just as water in a small river can bypass smooth rocks and continue to flow without rebounding.

Invisible clothing is different from invisible technology. Stealth technology will not make the plane invisible, but only reduce the cross section visible on the radar, making it difficult for the plane to be tracked. Invisibility cloak is an improved technology, which can hide people and objects and make visible light powerless. Sherig said in a telephone interview that in theory, it is beneficial for this technology to adapt to the concept of visible light, but from an engineering point of view, it is very challenging. But only five months after Sherig and his colleagues announced the feasibility of this theory, they successfully hid a cylinder from microwave detection.

Their experimental paper was published in the journal Science published on Friday. David smith, another author of the report, also from Dick University, said: "We finished the work quickly, so this invisibility cloak is not the best, but we know how to make a better one." Smith said that the first invisibility cloak was only two-dimensional, and it also cast a small shadow. The next step is to make a three-dimensional invisibility cloak to eliminate any shadows.

People can see things because an object scatters the light projected on its surface, and some light is reflected into people's eyes. Smith said: "The invisibility cloak reduces the reflection and shadow of objects, while the reflection and shadow of light can be detected. Once these two things are reduced, objects are difficult to detect. "

The invisibility cloak is made of a metamaterial, which is a mixture of metal and circuit board materials such as ceramics, Teflon and optical fiber synthetic materials. In the most ideal situation, the invisibility cloak and the objects it hides are invisible. The observer can see the things around him, but he can't see the objects covered by the invisibility cloak. Smith said: "Because we don't have a perfect invisibility cloak yet, the covered object can still reflect some light and have some shadows, which means that its background can still be seen, but it is darkened. We now need to improve the performance of the invisible material structure. "

He added that people can even imagine that this material can hide sounds without vibration. Lichnester, a researcher in the Department of Electronic Engineering and Computer Science at the University of Michigan, was not involved in the study, but he said that the study took the first step towards developing functional materials for civil and military use.

In addition, anyone who has seen the Harry Potter series knows that invisibility cloaks are mentioned many times in the book. There are two kinds of invisibility cloaks in the book: one is common, which mainly uses spells to achieve invisibility, but this method can't make people completely invisible, because few people have such strong power to achieve invisibility with spells (except albus dumbledore, Galotte Grindelwald and Voldemort), and the effect of this method is not ideal, because the intensity of spells will weaken with time. Another invisibility cloak is very precious, and there is only one-the one in Harry's hand: it can make people completely invisible and ignore the call of the summoning spell (mentioned in chapter 28 of Ha 7). This invisibility cloak was invented by Ignotus Peverell (Harry's ancestor), which belongs to one of the three deathly hallows and is also the most valuable one.