In 1842' s book Positive Philosophy, the French philosopher Auguste Comte once described the stars like this: "We can never understand their internal structures, and for some of them, we can never understand how their atmosphere absorbs heat." When it comes to planets, the philosopher holds the same view. "We will never know their chemical or mineralogical structure, let alone the organized creatures living on their surfaces," he wrote. In fact, Comte's conclusion is based on the fact that the distance between stars and planets and the earth is too far, which has exceeded our visual and geometric limits. He pointed out that although we can calculate their distance, movement and mass, we won't know anything else; We don't have any methods for chemical analysis of stars and planets.
Ironically, what the great philosopher said turned out to be all wet. /kloc-At the beginning of the 0/9th century, both William Hyde Wallerston and Joseph von Frenhoff discovered that the solar spectrum contained a large number of black lines. By the end of 1859, the secret of the black line was further revealed, and its name became "atomic absorption line". By analyzing this type of line, we can determine every chemical element that exists on the sun, which makes it possible to discover the composition of stars.
2. Determine the existence of meteorites
In the early development of Renaissance and modern science, astronomers refused to admit the existence of meteorites. The statement that these stones came from space was once labeled as "superstition" and "heresy". Opponents point out that how could God create such a chaotic universe? At that time, the French Academy of Sciences made a famous conclusion that "nothing can fall from the sky". The reports that fireballs and stones hit the ground have always been regarded as rumors and legends. These stones were once interpreted as "thunderstones", that is, the products of lightning strikes.
It was not until 1794 that the denial of the existence of meteorites came to an end. At that time, the physicist Ernst Kladni, who is famous for his works on vibration and acoustics, pointed out in a book that meteorites should come from outer space. 1790, a "stone rain" happened in Balbotham, France, when 300 people witnessed the process. It was this "stone rain" that prompted Kladni to publish his book.
However, Kladni's masterpiece On the Origin of pallas Iron and Other Similar Iron and Some Natural Phenomena Related to it failed to escape the fate of being laughed at and ridiculed. It was not until 1803 that his unjust case was cleared. At that time, Jean-Baptiste Diest Biot analyzed another "rain of stones" staged in Laegel and found conclusive evidence that these stones really came from space.
3. Airplanes heavier than air
A large number of scientists and engineers have confidently pointed out that it is impossible to fly heavier than air. For the Wright brothers' test flight, this conclusion is undoubtedly an unlucky prelude. Opponents believe that the brothers' dream of flying into the sky is impossible. Of all those who hold this view, Lord Kelvin is probably the most famous one. As early as 1895, he claimed that "it is impossible to make an aircraft heavier than air". However, only eight years later, the Wright brothers proved how ridiculous his argument was with hard facts.
What is even more incredible is that while Kelvin made this infamous assertion, scientists and engineers quickly approached the goal of flying above the air. From the late18th century, humans began to fly by balloon, and by the late19th century, balloons had been controlled by humans. Several designs, including Felix Du Temple's monoplane, also successfully flew into the blue sky, but the flight time was short. Having said that, we will inevitably have such questions-why do some people have doubts about flying heavier than air? This problem can be traced back to 17 16, when Emmanuel Sviden Berg, a scientist and theologian, described the design of an airplane in an article. He wrote: "This kind of plane seems easier said than done. Compared with human body, it needs more power and lighter weight. "
Like many other designs, Sviden Berg's plane is built on the flapping wing mechanism. In other words, before heavier-than-air flight becomes possible, we must design two truly effective wings. First of all, the two flapping wings must be replaced by a sliding mechanism. Secondly, engineers must have the ability to achieve a more ideal energy supply-internal combustion engine. Ironically, Nikolai Otto applied for the patent of internal combustion engine as early as 1877.
Go to space
Flying from the atmosphere to space is undoubtedly a qualitative leap, but the whole process is far more complicated than we thought. For a long time, the idea of sending anything into space and putting humans in orbit has been considered nonsense. Skeptics are well-founded, because at that time, after all, there was no relevant technology to do this. In order to realize space travel, the spacecraft must reach the escape speed-the speed per second is greater than 1 1.2 km before it can rush out of the earth. If the sound barrier is considered, the speed of the spacecraft is only 1238 km per hour. It was not until 1947 that humans successfully broke through the sound barrier for the first time. In jules verne's novel From the Earth to the Moon, the science fiction writer suggested using giant cannons. However, a sudden acceleration like this will kill all the passengers immediately. In addition, the calculation results also show that the strength of the gun is not enough for the spacecraft to reach the escape speed.
At the beginning of the 20th century, two rocket researchers-Konstantin Tsiolkovsky and robert goddard-finally solved this problem. Tsiolkovsky's research work was ignored by countries outside the Soviet Union; After his ideas were severely criticized, Goddard gradually faded out of the public eye. But in any case, the progress of science is unstoppable. 1957, the first artificial satellite "artificial earth satellite 1" was launched. Four years later, the first manned spacecraft successfully entered space. Unfortunately, due to their early deaths, tsiolkovsky and Goddard failed to experience these exciting moments.
5. Use nuclear energy
On February 29th, 1934 1934, the Pittsburgh Post quoted Albert Einstein as saying: "There is no indication that human beings can acquire and use nuclear energy. The use of nuclear energy means freedom, which means that atoms must be torn to pieces. " In the same year, before the report was published, Enrico Fermi found that if uranium was bombarded with neutrons, the uranium atoms would split into lighter elements and release a lot of energy.
Einstein's doubts were finally defeated by facts. By the end of 1939, people had a deeper understanding of nuclear fission, and researchers realized that a chain reaction-once started, the speed increased-could produce a huge explosion. Later, in 1942, the researchers staged a similar chain reaction in the experiment. 1August 6, 945, the first atomic bomb exploded over Hiroshima. Ironically, William Leahy, a five-star general, once said to Truman, then president, "I am an expert in blasting myself. In my opinion, this is the stupidest thing we have ever done, because this bomb will never explode. " 1954, the Soviet union became the first country to use nuclear energy to generate electricity with Obninsk nuclear power plant.
6. Discovering high-temperature superconductors
High-temperature superconductor is undoubtedly a strange guy-its superconducting phenomenon can be observed and measured, but this phenomenon should not have happened. According to the perfect superconductivity theory, superconductivity cannot occur above 30 Kelvin. Interestingly, some superconductors have the best conductivity at 77 Kelvin. Superconductors-they have no resistance when current passes through them-were first discovered in 19 1 1 year. In order to understand superconductivity, conductive materials are usually cooled to a temperature close to absolute zero.
In the next 50 years, scientists discovered and studied many superconducting materials. 1957, john bardeen, Leon Cooper and John schrieffer put forward a complete theory about superconducting materials-"BCS" theory, which explained the characteristics of standard superconductors in detail. According to BCS theory, electrons in superconducting materials move in the form of so-called Cooper pairs. If a "Cooper pair" is firmly combined, it can bear any influence of atoms in the material, and then achieve zero resistance. However, this theory also points out that zero resistance phenomenon can only be produced at extremely low temperature, when atoms only vibrate slightly.
In a famous paper published in 1986, johannes georg bednorz and Karl Alexander Mill reported that they found a material with superconductivity at the highest temperature of 35 Kelvin. The discovery of this material changed the face of the superconductor family, and they won the Nobel Prize in physics the following year. Later, Bednorz and Mill discovered materials that can be superconducting at higher temperatures. Up to now, the highest observed temperature (under pressure) is 164 Kelvin. But with the rapid development of scientific research today, this record may not last long.
7. Discover the existence of black holes
Those who think that black holes belong to futurism or modernism may be surprised to learn that the basic black hole theory was first put forward in 1783. At that time, geologist john mitchell mentioned black holes in a letter to the Royal Society. He pointed out that if a star has enough mass, then a celestial body falling from an infinite height will gain greater surface speed-even faster than the speed of light, so that all the light emitted by a celestial body will return by its own gravity.
However, in the whole19th century, the existence of black holes was once considered as a ridiculous idea, because physicists believe that light is a wave with "ether" as the medium and can be assumed to be massless, so it is "immune" to gravity. It was not until Einstein put forward the famous general theory of relativity in 19 15 that scientists had to take the black hole theory seriously. According to an important prediction of Einstein's theory of relativity, light will bend under the influence of gravity. Since then, arthur eddington has measured the position of the stars during the solar eclipse. The measurement results show that the light they emit is bent due to the gravity of the sun, but due to the limitation of the equipment used at that time, the observed bending effect is too small, so it is not reliable-the theory about the existence of black holes was officially recognized later.
After the establishment of the theory of relativity, black holes became a serious topic, and theorists such as subrahmanyan chandrasekhar elaborated their characteristics in detail. After that, astronomers began to look for black holes. More and more evidences prove that the black hole is similar to the celestial body in the center of many galaxies (including the Milky Way) in the universe, and it is the largest celestial body that produces high-energy cosmic rays. 2019 On April 10, the first black hole photos in human history were released simultaneously in China, Shanghai, Taipei, Brussels, Santiago de Chile, Tokyo, Japan and Washington, D.C., USA. This is the first time that humans have seen black holes intuitively through images.
8. Create a force field
Creativity field is a classic passage in science fiction. Due to the invention of "plasma window", the creative field finally became a reality in 1995. The "plasma window" was designed by Adi Hershkovich of Bukhaven National Laboratory. It can fill a small space with plasma or ionized gas through a magnetic field. The "plasma window" jointly developed by Hershkovich and Acceleron is used to reduce the energy consumption of electron beam welding.
The "plasma window" has most characteristics related to the force field. It can effectively block substances and act as a barrier between vacuum and atmosphere. In addition, it allows the laser and electron beam to pass unimpeded; If argon is used as the working gas of plasma, it can even emit blue light. The only drawback is that it takes a lot of energy to generate a "plasma window" of any size-the current samples are all small people. Theoretically, it is possible to develop a larger "plasma window".
9. Create stealth technology
Invisibility is another science fiction technology. From Richard Wagner's opera "The Gold of the Rhine" to Hull Joe Wells's "The Hollow Man" and then to Harry Potter's magic series, stealth technology can be said to be everywhere. In fact, there is no physical law that invisibility is impossible, and recent progress means that certain types of shielding equipment have become possible. In the past few years, we must have heard many reports about the "invisibility cloak" experiment, and a basic design was made in 2006. These devices rely on metamaterials to guide light around objects. The first invisibility cloak can only work on tiny objects, and it is in the microwave environment. Obviously, it is undoubtedly a great challenge to modify this design to make it used in visible light environment. Fortunately, this modification can be completed after 1 year, although the scope of action only reaches two dimensions and microns (one millionth of a meter). Undoubtedly, the engineering challenge of making a real "invisibility cloak" is still daunting.
10. Realize long-distance transmission of objects.
The term "teleportation" has a history of many years, but people have always been skeptical about this technology with strong sci-fi color. In the book, Lo! ",people heard about long-distance transmission for the first time. Since then, the word has become a "guest" of a large number of science fiction writers, and the "transporter" in Star Trek is the most famous one.
Although the origin of teleportation is very sci-fi, physicists have realized a kind of teleportation, which is attributed to a strange quantum phenomenon called entanglement. Entangled particles have the property that they should be connected no matter how far apart they are from each other. For example, if you change the rotation of an entangled electron, the rotation of its twin brother will also change.
Obviously, entangled particles can be used to transmit information over long distances. It was once thought that it was impossible to perform the same "performance" on anything larger than atoms, but in 2002, a theory related to entangled coupled molecules pointed out that they could be divided into quantum states, which was called "superposition". Recently, scientists put forward an alternative idea, dubbed "long-distance transmission of non-quantum physics", that is, building a beam of rubidium atoms, making them disappear in one place and then appear in another. Although this method does not rely on entanglement, it can transmit all the information about these atoms, that is, they can be "recreated" in another place by means of an optical fiber.