Invisibility is not that simple

  Invisibility is always full of mythology, it is like a fairyland in a dream, and it touches the hearts of many people! For thousands of years, people have been weaving magical stories with beautiful ideals. As a result, the West has the fairy tale of the invisibility hat, and the East has the legend of the invisibility grass… Then, do humans have invisibility? If there is a stealth technique, why haven’t you seen it in the wars of the past? If there is an invisibility technique, will it change human life?
  after a long period of time, gradually, people master the scientific way of thinking. At first, people progressed from the induction of things to the judgment of concepts, and then to the logical reasoning of things.
  People have already felt the presence of air. It cannot be seen because people know that the air is transparent. After that, people made glass, through which the scene in front can be seen because glass is transparent. People also understand that vision depends on the reflection and absorption of light by things (all reflection, the object is white; all absorption, the object is black); they understand that the transparent body neither reflects nor absorbs light, but makes light direct Through this basic physical phenomenon. As a result, people at this time are no longer satisfied with weaving stories to pin their fantasy.
  In some quick-thinking scholars, there has been such a reasoning: transparent matter is invisible; human beings are also a kind of matter, if human beings become transparent, invisibility will be realized.
  In the 18th century, the earth has entered a period of civilization. Advanced science and technology bring convenience to practice this reasoning. As a result, various weird experiments aimed at the transparency of the human body swept across Europe, the center of science and culture at that time, like a hot wind.
  An outstanding scientist of the Paris Medical Association dedicated his life to this. He got a translucent rabbit body with the skeleton and internal organs clearly visible, which was considered a very remarkable achievement at the time. This achievement inspired the confidence of hundreds of scientists and also inspired the well-known British science fiction novelist Wells at the time. Based on this, he successfully portrayed the protagonist in the novel “The Invisible Man”.
  Wells’s work is undoubtedly successful, and it still has a large audience today. Unfortunately, scientists who have struggled to make the human body transparent for more than a century have found nothing. In fact, they cannot gain anything. Because of the further discoveries of science in theory and technology, all their efforts were completely denied.

  The first problem that scientists encounter is how to make the basic substance of the human body-protein-transparent.
  It is known that chemistry can stain or decolor various substances. So scientists turned to chemistry. But people immediately discovered that protein was far from being dominated by people as they thought. This smallest unit of life is not hospitable. It refuses to accept all “givens” from the outside, and “prefers death than surrender”: Once invaded by foreign objects, the nucleic acids and amino acids that make up the protein are immediately decomposed and died. In the face of ruthless facts, scientists shook their heads like a rattle—they failed.
  However, the fact is more than that. Even if this problem is solved, there is still a second problem-refractive index.
  Major breakthroughs in various fields in modern optical research have made people know that transparent bodies of different densities have different refraction of light; moreover, transparent bodies at certain angles can also decompose light, such as a prism that can separate out the seven-color spectrum. The density and angle of the various substances that make up the human body are obviously different. Therefore, even if the whole body is transparent, people will see a colorful monster due to the different density and angle of this “transparent person”. This is another insurmountable gap.
  What’s more, the “invisible man” created by the above methods can only be a blind man!
  Physics and medicine tell us that the eye can see scenes because of the refraction of the cornea, vitreous body and lens, and the light sensitivity of the retinal cones and cylinders. If the cells that make up the human eye are also transparent and become the same density, then who will realize the function of refraction and reception of light!
  After understanding all the above, the scientist finally despaired.
  Since then, in the long years of more than 100 years, people dare not put forward new ideas on the ancient topic of invisibility.
  However, human society has moved along a curve since the day it was born. Failure will only make people more experienced.
Negation of negation

  At the beginning of reading this section, please remember this optical principle: light always advances along the shortest route.
  Classical physics created by Newton tells us that all matter in the universe interacts through force fields: electric charges interact through electric fields, and the earth and sun, tables and chairs interact through gravitational fields. The force field connects all matter together, forming a relative balance of space. In this balanced space, the shortest distance between any two points is a straight line. This is a concept that people already know.
  However, when the great Albert Einstein proposed general relativity in 1916, this concept was shaken in some scientific fields. The general theory of relativity states: under the action of a force field, space will bend! In this kind of bending, the shortest distance between two points should be a curve. However, light always takes the shortest route. Therefore, the light travels along a curve in the force field.
  In 1919, British scientists took the opportunity of a total solar eclipse to first verify this revolutionary theory. They pointed an astronomical telescope at the edge of the sun for observation. However, what appeared in the lens was not the sun, but a star blocked by the sun. This is enough to prove that Einstein’s words are right-people’s eyes are bent by the strong gravitational field near the sun, thus bypassing the sun.
  This amazing discovery awakened some sensitive scientists from their confusion and gave them enough courage to make a new denial of the denial of the invisibility technique. The argument they hold is eloquent: since people’s eyes can go around the sun, why can’t they go around a person who generates a force field like the sun?
Who will accomplish this mission

  The problem seems simple. As long as you create a “stealth suit” that can generate a powerful force field and wear it on your body, you can make people’s eyes go around the person’s body, move on in the original direction, and fall directly on On the scene blocked by him. As a result, this person became an “invisible person” who was invisible to anyone.
  General relativity tells people that this idea is feasible, and the rest is just a technical problem.
  However, this “but” is not simple. A normal person can only carry a maximum of 20 kilograms if he wants to remain flexible. How to make this “stealth suit” of only 20 kilograms produce a force field sufficient to deflect light? Moreover, what method will be adopted to keep the eyes of the people wrapped in the “stealth suit” from being deflected? Also, is this super strong field harmful to the human body? It can be seen that the burden on the shoulders of scientists is not easy. But the good news is that people have found a theoretical basis to hide themselves after all.
  Naturally, finding the road does not mean that you can reach the end of the road. At the end of 2017, American scientists found a way to bend the light around an object to achieve an invisible effect. They use “metamaterials” to make specific compounds whose characteristics are determined by the structure of the substance rather than the chemical composition.
  The substance of this “invisibility cloak” guides light around the surface of the object, which means that this special substance does not reflect light into the line of sight. So, what kind of special substance is it? Studies have shown that the electromagnetic properties of inhomogeneous composite materials can produce a substance with a variable refractive index, which can effectively block electromagnetic waves from entering a certain area or the line of sight of people, thereby achieving invisibility.
  When light hits the “invisibility cloak”, it will naturally flow through the hidden object and continue to spread in another direction. Therefore, the “invisibility cloak” neither reflects light nor produces shadows. To put it bluntly, this kind of “invisibility cloak” captures the light and then adjusts the direction of the light around these objects so that the human eye will not see it.
  At present, stealth technology has made major breakthroughs in the military. We know that the reason for the stealth aircraft is that it mainly relies on electronic radiation to prevent the other party’s radar from monitoring. Now, this kind of physical method can also achieve the invisibility effect, that is, the use of a special coating containing metal particles, which can absorb the light emitted by the radar, so that the light cannot be reflected.
  Now, we look forward to stealth technology can enter people’s lives. Perhaps in the near future, this technology will be used in the construction field. Suddenly the tall tower that blocked people’s sight was gone, the walls became transparent, and the bridge floated in the air like a rainbow. As an ancient proposition, the distant fantasy about invisibility is like a shining pearl, constantly emitting alluring brilliance!