Scientists like to say that any theory is worth something if it can be presented in a simple language that is accessible to a more or less prepared layman. The stone falls to the ground in such and such an arc with such and such speed, they say, and their words are confirmed by practice. Substance X added to solution Y will color it blue, and substance Z added to the same solution will give it a green color. In the end, almost everything that surrounds us in everyday life (with the exception of a number of completely inexplicable phenomena) is either explained from the point of view of science, or even, like, for example, any synthetics, is its product.
But with such a fundamental phenomenon as light, everything is not so simple. At the primary, everyday level, everything seems to be simple and clear: there is light, and its absence is darkness. Refracted and reflected, light comes in different colors. In bright and low light, objects are seen differently.
But if you dig a little deeper, it turns out that the nature of light is still unclear. Physicists argued for a long time, and then came to a compromise. It is called "Wave-corpuscle dualism". People say about such things “neither to me, nor to you”: some considered light to be a stream of particles-corpuscles, others thought that light was waves. To some extent, both sides were both right and wrong. The result is a classic pull-push - sometimes light is a wave, sometimes - a stream of particles, sort it out yourself. When Albert Einstein asked Niels Bohr what light was, he suggested raising this issue with the government. It will be decided that light is a wave, and photocells will have to be prohibited. They decide that light is a stream of particles, which means that diffraction gratings will be outlawed.
The selection of facts given below will not help to clarify the nature of light, of course, but this is not all an explanatory theory, but only some simple systematization of knowledge about light.
1. From the school physics course, many remember that the speed of propagation of light or, more precisely, electromagnetic waves in a vacuum is 300,000 km / s (in fact, 299,793 km / s, but such accuracy is not needed even in scientific calculations). This speed for physics, like Pushkin for literature, is our everything. Bodies cannot move faster than the speed of light, the great Einstein bequeathed to us. If suddenly a body allows itself to exceed the speed of light by even a meter per hour, it will thereby violate the principle of causality - the postulate according to which a future event cannot influence the previous one. Experts admit that this principle has not yet been proven, while noting that today it is irrefutable. And other specialists sit in laboratories for years and receive results that fundamentally refute the fundamental figure.
2. In 1935, the postulate of the impossibility of surpassing the speed of light was criticized by the outstanding Soviet scientist Konstantin Tsiolkovsky. The cosmonautics theorist elegantly substantiated his conclusion from the point of view of philosophy. He wrote that the figure deduced by Einstein is similar to the biblical six days it took to create the world. It only confirms a separate theory, but in no way can it be the basis of the universe.
3. Back in 1934, the Soviet scientist Pavel Cherenkov, emitting the glow of liquids under the influence of gamma radiation, discovered electrons, the speed of which exceeded the phase speed of light in a given medium. In 1958, Cherenkov, together with Igor Tamm and Ilya Frank (it is believed that the latter two helped Cherenkov to theoretically substantiate the discovered phenomenon) received the Nobel Prize. Neither the theoretical postulates, nor the discovery, nor the prize had any effect.
4. The concept that light has visible and invisible components was finally formed only in the 19th century. By that time, the wave theory of light prevailed, and physicists, having decomposed the part of the spectrum visible by the eye, went further. First, infrared rays were discovered, and then ultraviolet rays.
5. No matter how skeptical we are about the words of psychics, the human body really emits light. True, he is so weak that it is impossible to see him with the naked eye. Such a glow is called ultra-low glow, it has a thermal nature. However, cases have been recorded when the whole body or its individual parts shone in such a way that it was visible to the people around. In particular, in 1934, doctors observed in the Englishwoman Anna Monaro, who suffered from asthma, a glow in the chest area. The glow usually started during a crisis. After its completion, the glow disappeared, the patient's pulse quickened for a short time and the temperature rose. Such a glow is due to biochemical reactions - the glow of flying beetles has the same nature - and so far has no scientific explanation. And in order to see the ultra-small glow of an ordinary person, we have to see 1,000 times better.
6. The idea that sunlight has an impulse, that is, is able to influence bodies physically, will soon be 150 years old. In 1619, Johannes Kepler, observing comets, noticed that any comet's tail is always directed strictly in the direction opposite to the Sun. Kepler suggested that the comet's tail is deflected back by some material particles. It was not until 1873 that one of the main researchers of light in the history of world science, James Maxwell, suggested that the tails of comets were affected by sunlight. For a long time, this assumption remained an astrophysical hypothesis - scientists stated the fact that sunlight had a pulse, but they could not confirm it. Only in 2018, scientists from the University of British Columbia (Canada) managed to prove the presence of a pulse in light. To do this, they needed to create a large mirror and place it in a room isolated from all external influences. After the mirror was illuminated with a laser beam, the sensors showed that the mirror was vibrating. The vibration was tiny, it was not even possible to measure it. However, the presence of light pressure has been proven. The idea of carrying out space flights with the help of giant thinnest solar sails, expressed by science fiction writers since the middle of the twentieth century, in principle, can be realized.
7. Light, or rather, its color, affects even absolutely blind people. American physician Charles Zeisler, after several years of research, took another five years to make a hole in the wall of editors of scientific publications and publish a work on this fact. Zeisler was able to find out that in the retina of the human eye, in addition to ordinary cells responsible for vision, there are cells directly connected to the region of the brain that controls the circadian rhythm. The pigment in these cells is sensitive to blue color. Therefore, blue-toned lighting - according to the temperature classification of light, this is light with an intensity above 6,500 K - affects blind people as soporific as it does on people with normal vision.
8. The human eye is absolutely sensitive to light. This loud expression means that the eye responds to the smallest possible portion of light - one photon. Experiments carried out in 1941 at the University of Cambridge showed that people, even with average vision, reacted to 5 out of 5 photons sent in their direction. True, for this the eyes had to “get used to” the darkness within a few minutes. Although instead of “getting used to” in this case it is more correct to use the word “adapt” - in the dark, the eye cones, which are responsible for the perception of colors, gradually turn off, and the rods come into play. They give a monochrome image, but are much more sensitive.
9. Light is a particularly important concept in painting. To put it simply, these are shades in the illumination and shading of the fragments of the canvas. The brightest fragment of the picture is the glare - the place from which the light is reflected in the eyes of the viewer. The darkest place is the own shadow of the depicted object or person. Between these extremes there are several - there are 5 - 7 - gradations. Of course, we are talking about object painting, and not about genres in which the artist seeks to express his own world, etc. Although from the same impressionists of the early twentieth century, blue shadows fell into traditional painting - before them, shadows were painted in black or gray. And yet - in painting it is considered bad form to make something light with white.
10. There is a very curious phenomenon called sonoluminescence. This is the appearance of a bright flash of light in a liquid in which a powerful ultrasonic wave is created. This phenomenon was described back in the 1930s, but its essence was understood 60 years later. It turned out that under the influence of ultrasound, a cavitation bubble is created in the liquid. It increases in size for some time, and then collapses sharply. During this collapse, energy is released, giving light. The size of a single cavitation bubble is very small, but they appear in the millions, giving a stable glow. For a long time, studies of sonoluminescence looked like science for the sake of science - who is interested in 1 kW light sources (and this was a great achievement at the beginning of the 21st century) with an overwhelming cost? After all, the ultrasound generator itself consumed electricity hundreds of times more. Continuous experiments with liquid media and ultrasonic wavelengths gradually brought the power of the light source to 100 W. So far, such a glow lasts a very short time, but optimists believe that sonoluminescence will allow not only obtaining light sources, but also triggering a thermonuclear fusion reaction.
11. It would seem, what can be in common between such literary characters as the half-insane engineer Garin from “The Hyperboloid of Engineer Garin” by Alexei Tolstoy and the practical doctor Clobonny from the book “The Travels and Adventures of Captain Hatteras” by Jules Verne? Both Garin and Clawbonny skillfully used the focusing of light beams to produce heat. Only Dr. Clawbonny, having hewed out a lens from an ice block, was able to get fire and graze himself and his companions from hunger and cold death, and engineer Garin, having created a complex apparatus slightly resembling a laser, destroyed thousands of people. By the way, getting fire with an ice lens is quite possible. Anyone can replicate Dr. Clawbonny's experience by freezing ice in a concave plate.
12. As you know, the great English scientist Isaac Newton was the first to divide white light into the colors of the rainbow spectrum we are used to today. However, Newton initially counted 6 colors in his spectrum. The scientist was an expert in many branches of science and the then technology, and at the same time was passionately fond of numerology. And in it, the number 6 is considered devilish. Therefore, Newton, after much deliberation, Newton added to the spectrum a color that he called “indigo” - we call it “violet”, and there were 7 primary colors in the spectrum. Seven is a lucky number.
13. The Museum of History of the Academy of the Strategic Missile Forces displays a working laser pistol and a laser revolver. The “Weapon of the Future” was manufactured at the academy back in 1984. A group of scientists led by Professor Viktor Sulakvelidze completely coped with the set creation: to make non-lethal laser small arms, which are also unable to penetrate the skin of the spacecraft. The fact is that laser pistols were intended for the defense of Soviet cosmonauts in orbit. They were supposed to dazzle opponents and hit optical equipment. The striking element was an optical pumping laser. The cartridge was analogous to a flash lamp. The light from it was absorbed by a fiber-optic element that generated a laser beam. The range of destruction was 20 meters. So, contrary to the saying, generals do not always prepare only for past wars.
14. Ancient monochrome monitors and traditional night vision devices did not produce green images at the whim of inventors. Everything was done according to science - the color was chosen so that it would tire the eyes as little as possible, allow a person to maintain concentration, and, at the same time, give the clearest image. According to the ratio of these parameters, the green color was chosen. At the same time, the color of the aliens was predetermined - during the implementation of the search for alien intelligence in the 1960s, the sound display of radio signals received from space was displayed on monitors in the form of green icons. Cunning reporters immediately came up with the "green men".
15. People always tried to light their homes. Even for the ancient people, who kept the fire in one place for decades, the fire served not only for cooking and heating, but also for lighting. But in order to systematically centrally illuminate the streets, it took millennia of civilization development. In the XIV-XV centuries, the authorities of some large European cities began to oblige the townspeople to light the street in front of their houses. But the first truly centralized street lighting system in a large city did not appear until 1669 in Amsterdam. The local resident Jan van der Heyden proposed to put lanterns at the edges of all streets so that people would fall less into numerous canals and be exposed to criminal encroachments. Hayden was a true patriot - a few years ago he proposed creating a fire brigade in Amsterdam. The initiative is punishable - the authorities offered Hayden to take up a new troublesome business. In the story of lighting, everything went like a blueprint - Hayden became the organizer of the lighting service. To the credit of the city authorities, it should be noted that in both cases, an enterprising city dweller received good funding. Hayden not only installed 2,500 lampposts in the city. He also invented a special lamp of such a successful design that Hayden lamps were used in Amsterdam and other European cities until the middle of the 19th century.
