2023-12-05 09:23:00
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Chu Junhaoa venerable 78-year-old physicist and distinguished director of the Faculty of Science at Donghua University, has dedicated his life to the research of metamaterials, those amazing laboratory-made structures capable of altering their physical properties through the application of electrical currents.
With this knowledge, Chu has embraced a challenge that seemed to belong only in the realm of fantasy: invisibility.
During a presentation that seemed straight out of a science fiction story, Chu and his team demonstrated how invisibility becomes reality. On a lit stage, two assistants held a transparent panel in front of the scientist. With a simple 90-degree turn, Chu’s legs vanished before the stunned eyes of the audience.
invisible animals
This act of “magic” was due to the panel’s lenticular grid, an intricate series of convex cylindrical lenses capable of refracting light so that the invisible becomes visible. Chu’s vision is not limited to academic laboratories. With inspiring confidence, he proclaimed: “In the future, everyone will have their own Harry Potter-style ‘invisibility cloak’ in their closets.”
It’s nothing new
Although the presentation was spectacular and Chu is a great researcher in metamaterials, what we have actually seen here is a simple magic trick that has nothing new. The secret lies in the call lente de Lubor.
The Lubor lens, named after its creator, the Czech chemical engineer and amateur magician Lubor Fiedler (1933-2014), is a unique optical device. This lens is made up of a lenticular sheet formed by a series of parallel lenses that function similarly to a prism, deflecting the light that passes through them.
This particular arrangement allows objects aligned with the ridges of the lenses to be blurred to the point of being almost invisible. On the other hand, objects that are placed at right angles to these lines are minimally affected, especially if they do not have large variations in their length, as could be the case with a pencil or the handle of a hammer.
The unique ability that allows fireflies to produce light
All in all, there are significant advances in the field of metamaterials, in which Chu is an expert.
Metamateriales
Los metamateriales They are artificial materials designed to have properties not found in nature, especially regarding their interaction with electromagnetic waves. They are structured in a way that they can manipulate these waves in unusual and often surprising ways. One of the most fascinating and widely discussed uses of metamaterials is their potential to achieve invisibility.
Metamaterials are composed of structural elements smaller than the wavelength of the light they manipulate. This structure allows them to interact with light in ways that natural materials cannot.
Some metamaterials have a negative refractive index, a property not found in natural materials. This means they can bend light in opposite directions to any natural material.
They can be designed to affect various properties of waves, such as their phase, amplitude, and direction.
The evolution of invisibility
When it comes to invisibility, experiments so far have managed to hide small objects under very specific conditions and usually only for certain wavelengths of light, such as microwaves. Invisibility in the visible spectrum remains a great challenge.
Invisibility cloaks that operate in the visible spectrum would have to handle a very wide range of wavelengths and do so from all possible angles, which is extremely difficult with current technology.
Chinese scientists, following in Chu’s footsteps, have carried out pioneering research in the field of invisibility. A notable example is that of a group of students from Wuhan University, who, in a contest sponsored by Huawei, revealed InvisDefense, a coat that defies perception and surveillance technology. This coat, capable of hiding the individual from both daytime CCTV cameras and nighttime thermal imaging cameras, has become a viral phenomenon in China.
Wei Hui, leader of the student team, explains the sophistication of InvisDefense: “The challenge was to create a camouflage pattern that could fool computer vision without standing out to human eyes.” The shelter, thanks to its innovative algorithms, reduced pedestrian detection accuracy by 57% in tests carried out. However, Wei and his team are not seeking to undermine security systems; Its objective is to strengthen visual recognition technology and improve security.
This research is not limited to the civil sphere. The Chinese military has integrated the metamaterials into military prototypes, as a “cloak” that can hide ground targets from radar satellites.
In Nanjing, a team led by Cui Tiejun has taken invisibility to the skies, developing a metamaterial cloak for fighter jets. “Our ghost illusion device can make an aircraft undetectable to military radar.”
These innovations are not mere scientific curiosities: they are the vanguard of a revolution that promises to redefine the limits of what is possible. In this new world, invisibility, a concept once relegated to the pages of fantasy literature, becomes a tangible reality, unfolding a range of possibilities that until now we could only imagine.
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