Ether is a historical term, and its meaning develops with the development of history.
In ancient Greece, ether refers to the blue sky or upper atmosphere. In cosmology, it is sometimes used to represent the matter occupying celestial space. /kloc-R. Descartes in the 0/7th century was a philosopher who had a great influence on the development of scientific thought. He was the first person to introduce science and give him some mechanical properties. In Descartes' view, all forces between objects must be transmitted through some intermediate substance, and there is no distance effect. So space can't be empty, it is full of the medium of ether.
/kloc-in the 0/7th century, Descartes (March 365438 +0, February 65438 +65438 +0650) thought that matter was composed of particles, and particles were the only entity, the essence of matter was its spatial extensibility, and mechanical movement, that is, the change of position, was the only movement form of matter. All natural phenomena and all material properties (including color, fragrance, hardness, heat, etc. ) are caused by the mechanical interaction of matter particles. With the movement of matter (space) and (machinery), the whole world can be built according to the natural laws of material movement itself, without the care of God. This mechanistic view of nature has dominated natural science for more than two centuries. He also believes that matter is full of space, that is, there is no vacuum (it is irrational to say that there is absolute void or space without objects), matter can be infinitely divided (there can be no atoms or material parts inseparable from nature in the universe), and space is infinite (the vastness of the world is infinite), and he affirmed the unity and diversity of the material world (the matter in heaven and underground is the same, and the world is not pluralistic), and "all matter" Therefore, Engels Descartes' methodology has an important influence on the later development of physics.
Descartes applied his mechanistic views to celestial bodies and formed his theory on the origin and structure of the universe. He believes that it is easier to understand things from the perspective of development than just from the existing form. He explained the formation process of celestial bodies, the sun, planets, satellites and comets. For the first time, it relied on mechanics instead of theology, and used the vortex model (pictured). He believes that the motion of celestial bodies comes from inertia (tangent to orbit) and some cosmic substances. The pressure of etheric vortex on celestial bodies must have a celestial body (such as the sun) at the center of various vortex sizes. This hypothesis is used to explain the interaction between celestial bodies.
Descartes' theory of celestial evolution, vortex model and viewpoint of near motion, like his whole ideological system, on the one hand, have rich physical thoughts and rigorous scientific methods, which played a role in opposing scholasticism, inspiring scientific thinking and promoting the progress of natural science at that time, and had a far-reaching impact on the thoughts of many natural scientists. On the other hand, it often stays in the intuitive and qualitative stage, rather than starting from quantitative experimental facts, so some concrete conclusions often have many defects, which have become the main opposites of Newtonian physics and caused extensive debates.
Nevertheless, as a natural scientist and philosopher, Descartes' materialism has become the real wealth of natural science.
Today, when we understand the whole universe system from the viewpoint of the unified field of matter and magnetism, it is obvious that one of the biggest omissions of Descartes' view of ether lies in separating ether from the microscopic particles of celestial bodies and matter. If Descartes closely combined ether with celestial bodies and microscopic particles and thought in an integrated way, human scientific and technological progress would take fewer detours and the level of science and technology would far exceed today's state.
Newton,1643 65438+1October 4th, was born in Lincolnshire, England. 1686, he published his law of gravity based on J. Kepler's law of planetary motion, and used it to explain the motion of the moon and planets and tidal phenomena, which was a great discovery. It seems that Newton's law of universal gravitation seems to support the viewpoint of action at a distance, but Newton himself does not agree with the explanation of action at a distance. In a famous letter to R. Bentley, he wrote: "It is hard to imagine that inanimate and unconscious substances can act and influence other substances without touching each other. ..... Gravity is natural, inherent and fundamental to matter, so there is no other medium, and one object can act on another object through vacuum. With it, the force can be transferred from one object to another. In my opinion, this idea is ridiculous. I believe that people who have full thinking ability on philosophical issues will not be addicted to it. " Newton himself tended to take an etheric view. In a letter to R. Boyle, he privately expressed his belief that he would eventually find some material function to explain gravity. However, the specific idea of ether is different from that of R. Descartes, who was quite influential at that time, only in the details.
As we all know, Newton held the particle theory when he understood the nature of light. But when he discussed the nature of light with Hooke and Huygens, he said that light has one or another instinct to excite the vibration of the ether. This means that ether is the medium of light vibration. Here, Newton seems to understand the duality of light. Actually, it is not. His view on the existence of ether medium is very similar to that of ubiquitous air, but it is much thinner, finer and more elastic. He reiterated that it is the etheric animal temperament that makes muscles contract and stretch, and animals can exercise. He further explained the reflection and refraction of light, transparency and opacity, and the generation of color (including Newton's ring). He even imagined that the gravity of the earth was caused by the constant condensation of etheric temperament. At the end of the explanation in chapter 6 of the second part of Principles, it is said that from memory, he has done experiments and tends to say that ether fills the gaps of all objects, although ether has no perceptible influence on gravity.
Since 14 and 15 centuries, European scholars have been fascinated by ether, and the theory of ether has become all the rage. Later, the great scientist Descartes was convinced of the existence of ether. He thinks that the motion of planets can be explained by too much vortex. Etherism became a temporary philosophical trend of thought. Newton, who respected experiments, was inevitably involved in this philosophical trend of thought and tended to exist. At that time, people had different views on the function of distance. Newton once put forward his gravitational interaction theorem, which is not considered as the final explanation, but just a law summarized from experiments. So Newton did not come to a conclusion about the nature of gravity.
But Newton clarified in the last paragraph of the second part of the Principles that the vortex hypothesis has nothing to do with celestial motion.
Obviously, Newton, like Descartes, did not unify matter with ether and thought. Therefore, it is a pity that "the gravitational interaction theorem is not considered as the final explanation, and no conclusion has been made on the nature of gravity". Today, starting from the duality principle of matter, it is obvious that we can sum up the fundamental relationship between ether and the universe and matter, and then have a deeper and more essential understanding of the whole universe.
According to the viewpoint of the ether, although it can't be felt by human senses, it can transmit the effects of forces, such as magnetism and the effect of the moon on the tides. Later, as the load of light waves, ether was largely related to the wave theory of light. The wave theory of light was first put forward by Hooke and further developed by Huygens. For a long time (until the beginning of the 20th century), people's understanding of waves was limited to the mechanical vibration of a certain medium. This medium is called wave load, for example, air is the load of sound wave. As light can travel in a vacuum, Huygens proposed that the dielectric substance (ether) carrying light waves should fill all the spaces including vacuum and penetrate into ordinary substances. In addition to being the load of light waves, Huygens also used it to explain the phenomenon of gravity.
Newton disagreed with Hooke's light wave theory, but like Descartes, he opposed the action at a distance and admitted the existence of ether. In his view, ether is not necessarily a single substance, so it can transmit various functions, such as generating different phenomena such as electricity, magnetism and gravity. Newton also thought that ether can propagate vibration, but the vibration of ether is not light, because the wave theory of light (shear wave was not known at that time, and light wave was considered as longitudinal wave like sound wave) can not explain the polarization of light, nor can it explain the phenomenon of straight-line propagation of light.
18th century is the period of the decline of Etherism. Because French Descartes refused to be attracted by inverse square law, Newton's followers rose up against Descartes' philosophical system, and his etherism was also opposed. With the success of gravitational inverse square law in celestial mechanics and the lack of practical results in exploring ether, the viewpoint of action at a distance became popular. The wave theory of light has also been abandoned, and the particle theory has been widely recognized. By the end of18th century, it was proved that the force between charges (and between magnetic poles) was also inversely proportional to the square of the distance. Therefore, the concept of electromagnetic ether has been abandoned, and the viewpoint of action at a distance has also occupied a dominant position in electricity.
In the19th century, the revival and development of Etherism began with optics, which was mainly the result of the work of T. Young and A. J. Fresnel. Yang explained Newton's ring with the interference of light waves, and in 18 17, inspired by experiments, he put forward a new view that light waves are intersecting (shear waves in elastic bodies were not studied at that time), which solved the problem that wave theory could not explain the polarization of light for a long time. It can be seen that the revival and development of the concept of ether is conducive to promoting scientific and technological progress.
Fresnel successfully explained the diffraction phenomenon of light with wave theory. His theoretical method (now often called huygens-fresnel principle) can correctly calculate the diffraction pattern and explain the straight-line propagation phenomenon of light. Fresnel further explained the birefringence of light and achieved great success. In 1823, according to Yang's theory that light waves intersect, and his own hypothesis that the density of ether in transparent materials is directly proportional to the quadratic square of its refractive index, under certain boundary conditions, he derived famous formulas about the amplitude of reflected light and refracted light, which well explained the experimental results measured by D. Bourdette several years ago.
One of Fresnel's important theoretical work on ether is to derive the velocity formula of light in a transparent object moving relative to the Ethernet frame of reference. In 18 18, in order to explain the starlight refraction experiment, he proposed on the basis of Yang's thought that the density of ether in transparent matter is directly proportional to the quadratic square of the refractive index of matter, and he also assumed that when an object moves relative to the ether reference frame, only the part of ether inside it that is out of vacuum is driven by the object (ether partial traction hypothesis). From this, the average speed formula of ether in an object can be obtained: (1- 1/nn)v, where v is the speed of the object.
Using the above results, it is not difficult to deduce that in the Ethernet frame of reference, the speed of light in a moving object is (accurate to the first power of v/c), and u=c/n = (Park-1/nn)vcoso, where o is the included angle between u and v. The above formula is called Fresnel formula of the speed of light in a moving medium. The later Fizeau test confirmed this.
In the middle of19th century, some experiments were carried out to show the effect caused by the movement of the earth relative to the etheric frame of reference, and the velocity v of the earth relative to the etheric frame of reference was measured, but the results were all negative. These experimental results can be explained by the above Fresnel theory. According to the formula of light speed in Fresnel moving medium, when the experimental accuracy only reaches the order of v/c, the speed of the earth relative to the etheric reference frame will not be shown in these experiments. To measure V, the accuracy should at least reach the order of vv/cc (estimated vv/cc= 10**-8), but the experiment at that time did not reach this accuracy.
Through the work of Yang and Fresnel, the wave theory of light established its position in physics. However, there are also some problems with etherism. First of all, if light waves are shear waves, then ether should be an elastic solid medium. In this way, some people put forward the explanation that the celestial body is not subject to resistance when it runs: ether may be a plastic substance similar to wax or asphalt, elastic enough to vibrate as fast as light, like a solid, but moving as slowly as a celestial body is like a fluid. In addition, there should be longitudinal waves besides transverse waves in elastic media, but experiments show that there is no longitudinal wave. How to eliminate the longitudinal wave of Ethernet and how to obtain the boundary conditions needed to derive the reflection intensity formula are long-term controversial problems in various Ethernet models. It seems difficult for optics to meet the requirements of ether properties with ordinary elasticity. In order to meet the needs of optics, people have to assume some extraordinary properties of ether, such as 1839 Michael model and Assi model. For another example, because the refractive index n of different optical frequencies is different, the traction coefficient of different frequencies will be different. In this way, each frequency of light must have its own ether and so on.
Subsequently, ether also gained a position in electromagnetism, which was mainly attributed to the contributions of M Faraday and J·C· Maxwell. In Faraday's thought, the idea that function is gradually transmitted has a very solid position. He introduced magnetic lines of force to describe the magnetic and electrical effects. In his view, lines of force are real, space is full of lines of force, and light and heat may be the lateral vibration of lines of force. He once suggested that the force line should replace the ether, and thought that the atoms of matter might be the force line field gathered near a snack. In 185 1, he wrote: If we accept the existence of optical ether, it may be the load of force line. "But Faraday's point of view was not accepted by theoretical physicists at that time.
By1early 1960s, Maxwell put forward the concept of displacement current, and on the basis of predecessors' work, put forward a set of differential equations describing the universal laws of electromagnetic fields. This set of equations will be called Maxwell equations in the future. According to Maxwell's equations, it can be concluded that the disturbance of electromagnetic field propagates in the form of waves, and the speed of electromagnetic wave in air is 3. 1 * 10 * * 8m/s, which is consistent with the known speed of light in air at that time. "Later, H.R. Hertz confirmed the existence of electromagnetic waves by experimental methods (1888). The electromagnetic theory of light successfully explains the properties of light waves, which makes ether not only gain a position in electromagnetism, but also the electromagnetic ether and optical ether are unified.
Maxwell also imagined that electromagnetic phenomena could be explained by too many mechanical movements. In his paper 1855, he compared the magnetic induction intensity b with the speed of ether. Later (186 1 year-1862) accepted the viewpoint of W. Tang Musun (that is, Kelvin), and changed it to magnetic field for rotation and electric field for translation. He believes that the ether rotates around the magnetic field lines to form vortex elements, and there is a layer of charged particles between adjacent vortex elements. He also assumed that when these particles deviate from their equilibrium position, that is, there is displacement, they will exert a force on the substance in the vortex element and cause the deformation of the vortex element, which represents the electrostatic phenomenon.
There is a certain correspondence between electric field and displacement, which is not a brand-new idea. W Tang Musun once compared the electric field to the displacement of the ether. In addition, Faraday proposed earlier (1838) that when an insulating substance is placed in an electric field, the charge in it will shift. The difference between Maxwell and Faraday is that he thinks that no matter whether there is insulating material or not, as long as there is an electric field, there will be the displacement of etheric charged particles, and the displacement D is proportional to the electric field intensity E. When the displacement of charged particles Z changes with time, a current will be formed. This is what he called current) is the real current.
During this period, other Ethernet models were established. Although Maxwell made great progress in electromagnetic theory, neither he nor Hertz later tried to extend electromagnetic theory to moving matter.
In 1990s, H.A. Lorenz put forward a new concept. He attributed the electromagnetic properties of matter to the electronic effect related to atoms. As for the ether in matter, it is no different from the ether in vacuum in density and elasticity. He also assumed that when an object moves, it will not drive the etheric motion in it. However, when the electrons in an object move with the object, they are not only forced by the electric field, but also by the magnetic field, and when the object moves, there will be a dielectric moving current in it, so the speed of electromagnetic waves in moving matter is different from that in static matter. After considering the above effects, he also derived the Fresnel formula about the speed of light in moving matter. However, the difficulties encountered by Fresnel theory (light with different frequencies has different ethereum) no longer exist. Lorenz can deduce the change of refractive index with frequency from the strong vibration of bound electrons. Lorenz's above theory is called electronic theory, and he has achieved great success.
The end of 19 can be said to be the heyday of etherism. But in Lorenz theory, ether has no other movement and change except electromagnetic vibration. In this way, it almost degenerates into some abstract symbol. Except as the load and absolute reference system of electromagnetic waves, it has lost all other concrete and vivid physical properties. This created conditions for its decline.
In order to measure the movement of the earth relative to the Ethernet frame of reference, as mentioned above, the experimental accuracy must reach the order of vv/cc. By the 1980s of 19, the experiment made by A.A. Michelson and E.W. Morey reached this accuracy for the first time, but the result was still negative (that is, the earth did not move relative to the ether). Since then, other experiments have achieved the same result. Therefore, the ether further lost its nature as an absolute frame of reference. This result makes the principle of relativity universally recognized and extended to the whole field of physics.
At the end of 19 and the beginning of the 20th century, although some efforts were made to save the ether, it was finally abandoned by physicists after the establishment of the special theory of relativity. The accepted concept is that the electromagnetic field itself is a form of matter, and the field can spread in the form of waves in a vacuum. The establishment of quantum mechanics strengthens this phenomenon, because people find that the motion of atoms of matter and particles such as electrons, protons and neutrons that make up them also has the nature of waves. Fluctuation has become one of the basic properties of material movement. The narrow view that wave is only understood as mechanical vibration of a certain medium has been completely broken.
However, people's understanding is constantly developing. After the mid-20th century, people gradually realized that vacuum is not absolutely empty, and there is a continuous fluctuation process (the generation and subsequent annihilation of virtual particles). This vacuum fluctuation is the quantum effect of the interaction field. Today, theoretical physicists have further discovered that vacuum has more complex properties. The vacuum state represents the ground state of the field and is degenerate. The actual vacuum is a specific state among these degenerate states. Many symmetry breaking observed in particle physics at present are caused by this special "orientation" of vacuum. Based on this view, the unified theory of weak interaction and electromagnetic interaction has achieved great success.
In this way, although the mechanical ether is dead, some spirits of the ether (no distance effect, no vacuum in the sense of absolute emptiness) are still alive and have strong vitality.
In a word, after its birth in the14th century, Etherism experienced three centuries of development, growth and decline, then died out in the17th century, revived, developed, expanded and declined again in the18th century, and finally reached a complete failure at the beginning of the19th century, even now 2/kloc. It can be seen that the development path of ether is a tortuous progress course on the road of human science and technology. This is a glorious course to improve and perfect the level of human understanding of nature. Therefore, the revival of etherism is a new hope and dawn for human beings to understand nature.
At the end of 19, during the development of electromagnetic theory of light, some people thought that the universe was full of a medium called "ether", and light propagated through the ether, so this "ether" was chosen as an absolutely static frame of reference, and any movement relative to this absolute frame of reference was called absolute movement, which was different from that relative to other frames of reference. Classical electromagnetic theory can only be established in an inertial system that is static relative to the ether. According to this view, physicists at that time designed various experiments to find the etheric reference system. Among them, from 65438 to 0887, the experiments of A.A. Michelson and E.W. Molly were particularly famous. According to their hypothesis, if there is an ether, and the ether is not driven by the movement of the earth at all, then the speed at which the earth moves towards the ether is the absolute speed of the earth. Using the difference between the absolute speed of the earth and the speed of light in the direction, we should get some expected results in the Michelson interferometer experiment, so as to get the absolute speed of the earth relative to the ether.
Michelson and Morey have done many experiments in different geographical conditions and different seasonal conditions, but they have never seen the movement of interference fringes. Unexpectedly, the experiment originally carried out to verify the Ethernet frame of reference inadvertently presented evidence to deny the Ethernet frame of reference, which was not accepted by the whole physics community until now. It is under this condition that the special theory of relativity broke ground.
However, due to the duality of wave and particle, light is a very, very tiny energy individual, which is not only a straight line propagation (running), but a spiral trajectory with fluctuation characteristics. Although light wave is a kind of electromagnetic wave, it does not propagate spherically like most electromagnetic waves. Therefore, light particles don't propagate by ether, but just like boring bullets, they run in a straight line (spiral line) in one direction, and only need to start energy, without the propagation of the medium, and they can't simply be equated with the continuous spherical expansion transmission of the mechanical energy of sound waves in its medium. At the same time, it is subjective and one-sided to choose "ether" as the absolute static frame of reference. Because, why should the ether be absolutely static? If "Ether" is not an absolutely static material system, but a synchronous and dense material system related to the movement of galaxies, then before the end of 19, people will only regard "Ether" as an absolutely static reference system, which will inevitably lead to wrong conclusions and wrong theoretical systems! If the ether distributed on the earth's surface is in the same direction and synchronous with the earth's running speed (revolution and rotation), as described in On the Unified Field. Then in 1887, the optical interference experiment done by A.A. Michelson and E.W. Morley to prove the existence of ether should actually be a scientific conclusion that ether definitely exists. That is to say, the experiment is definitely correct, and the assumption of "absolute static ether" is wrong, thus drawing a historic and completely different scientific conclusion! ! !
Obviously, Michelson and Morey's optical interference experiment to verify the etheric reference system cannot be used as evidence to deny the etheric reference system because of its incomplete preconditions, although it has been recognized by the world physical science community for more than one hundred years. Therefore, it is a historical mistake or illusion to deny the experimental conclusion of ether.
Furthermore, when the ether does exist, and it is not absolutely static, then Einstein's theory of relativity, which is only based on coordinate transformation, is naturally only a mathematical transformation and does not necessarily have exact physical significance. Moreover, the theory of relativity does not decipher the material properties of this special substance and the specific mechanism of gravity transfer and action, but is only a mathematical description. Although a mathematical description form that can't directly reveal its physical meaning and material essence claims to be very accurate, it is obvious that there is still a certain gap, even a considerable gap, in its profound understanding of material essence and systematic and comprehensive decoding. So Einstein himself pursued the simplicity of theory very much, and continued to explore the unified field theory for decades until his life. When he was unable to unify the whole country, he also had high hopes for future generations.