Ethereum Berlin
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Japan
among Asian countries, Japan seems to be the first country to support cryptocurrency. On the contrary, in the past few years, China has been cracking down on ICO and closing down the trading business of digital currency exchanges in China. Compared with China's strict restrictions, Japan is undoubtedly far ahead in the field of cryptocurrency
maybe it's because of the anonymous people (or teams?) who developed bitcoin Japan's pseudonym is Nakamoto, so Japan's friendliness to cryptocurrency ranks at the top
after being attacked by hackers, the Japanese based Mt. GOx exchange finally closed down in February 2014, which is still the biggest scandal in the digital currency world. After that, Japan's licensed cryptocurrency exchanges came together to form a new self regulatory organization, which put forward guidelines to legalize ICO and formulated clear instry standards to protect investors, while allowing the instry to grow and continue to innovate
members of this association, called ICO business research group, include members of Parliament, academics, bankers and the CEO of bitflyer. Bitflyer is the largest cryptocurrency exchange in Japan. According to the government study, the legislature may allow potentially profitable ICO and cryptocurrency exchanges to continue trading, but at the same time, it must provide the government with more insight into these activities and enhance transparency
blockchain, and each token is said to be supported by one barrel of crude oil. However, analysts generally believe that Maro is obviously lying
nevertheless, as of the end of April, it was reported that Venezuela could offer India a 30% discount if India used petro currency to pay for its crude oil. Bitcoin magazine reported that "Venezuela has assured the buyer that petro currency will have all the functions of legal tender, can pay taxes and can be converted into Venezuelan hard currency, namely Bolivar
while many people are skeptical of petro itself and the Venezuelan government's move to integrate cryptocurrency into its declining economy, others believe that any effort to win the credibility of cryptocurrency is worthwhile. David Garcia, senior vice president and partner of ripio credit network, pointed out that Latin America is going through a transitional period
Latin America is in a difficult situation e to political corruption and economic crisis, and is troubled by high inflation and rapid devaluation of local currency, especially in Venezuela. Garcia believes that innovative ideas and solutions such as blockchain and cryptocurrency are necessary for these countries to develop in a positive direction3. Sweden
in 2015, Sweden became the first country in Europe to approve the trading of two kinds of bitcoin exchange traded notes (ETN), which are managed by XBT providers. The Swedish Krona denominated bitcoin tracker one XBT (ST: se0007126024) fund and bitcoin tracker EUR XBT provider (ST: se0007525332) can be traded on Nordic Nasdaq, the main Swedish exchange
since its launch, XBT has been launched in Denmark, Finland, Estonia and Latvia. As of early December 2017, cointegraph announced that Sweden's ETN "is more than 80% of the US ETF". In mid January, CNBC said that Sweden's bitcoin investment project attracted $1.3 billion
in addition, the Swedish central bank has been considering the development of an electronic currency called e-krona to cope with the situation that Sweden is rapidly becoming the first cashless society in the world. However, Sweden's banking sector has hit back. Hans Lindberg, chief executive of the Swedish Bankers Association, said in an interview on April 17: "in terms of e-money, there is already a lot. There are bank cards, credit cards... And other electronic solutions. The most likely scenario in the future is that the Swedish central bank will stick to wholesale business. "< However, James Pomeroy, a global economist at HSBC, believes that Sweden is still likely to become the first country in the world to issue digital currency, which may be launched in the next few years. Venezuela may be ahead in government supported cryptocurrency issuance, but Sweden, a Scandinavian country with stronger economy and more trusted regulators, may still disrupt the existing order of cryptocurrency and even lead the European cryptocurrency instry< Switzerland
4. The Swiss financial market supervision authority is at the forefront in clarifying the regulation of cryptocurrency and supporting ICO. Marc bernegger, a Swiss financial technologist, cryptocurrency entrepreneur and consultant to Swiss real coin, said Switzerland has traditionally been a haven of wealth. To some extent, this benefits from Switzerland's more open financial regulation and a long culture of protecting the privacy of Swiss banking institutions' customers. Bernegger pointed out that Switzerland has been "looking forward" to cryptocurrency assets as part of overall wealth management and is "preparing for changing economic forms."
the surrounding area of Zug in North Central Switzerland is called crypto Valley, which has been called crypto valley since Ethereum ICO was launched in 2014. For cryptocurrency entrepreneurs, developers and investors, cryptovalley is one of the most active ecosystems,5. Israel
in Israel, discussions on the regulation of cryptocurrency continue, and legislators are looking for ways to protect investors. Although Israel's banking system has failed to help promote bitcoin related business, Union Bank of Israel, the sixth largest bank in Israel, is being sued by a local cryptocurrency miner for stopping transferring funds from bitcoin exchange to the miner; In addition, Israel's second-largest bank, bank Leumi, was intervened by the district court and the country's Supreme Court when it tried to block the account activity of a local cryptocurrency exchange. This is undoubtedly a major victory for the local cryptocurrency instry
in addition, it has recently been reported that the Central Bank of Israel has been considering the possibility of issuing state supported cryptocurrency for several months. According to the Jerusalem Post, an anonymous source said, "digital shekel can record every transaction through mobile phones, making tax evasion more difficult." If a digital Shekel is introced, its value will be equal to that of an entity
in terms of technological innovation, Israel's start-up corporate culture is at the forefront. Roy meirom, co-founder and vice president of business development of wemark, pointed out that many of the 300 multinational R & D centers operating in Israel are committed to the application of blockchain<
Roy meirom also said that this small middle east country, commonly known as the "start-up country", is rapidly becoming the development center of blockchain< Bermuda
Bermuda, a member of the Commonwealth in the North Atlantic and Caribbean, has been actively seeking the adoption of cryptocurrency related regulations to begin to establish an appropriate framework to promote cryptocurrency business activities, including cryptocurrency exchanges, wallet services and payment providers. Recently, the Bermuda Monetary Authority's virtual currency business act was passed in the house of Commons
Bermuda has carried out relevant legislative activities on ICO in the form of amending the Companies Act 1981 and the limited liability companies act 2016. At the end of last year, Bermuda's prime minister and Finance Minister David Burt set up a blockchain working group, which is divided into two groups: the legal and regulatory Working Group on blockchain and the commercial working group on blockchain
7. Berlin, the capital of Germany, is perhaps one of the EU's most cryptocurrency friendly cities. In 2013, Berlin was called the "bitcoin capital of Europe" by the guardian, and it has always maintained this status. At present, people can use bitcoin to buy apartments in Berlin, make holiday reservations, and pay for meals in various fashionable local restaurants
Thomas Schouten, marketing director of lisk, a Swiss based blockchain application platform, said the application chain has a major contractor office in Berlin. Schouten said Berlin provides a vibrant start-up and technology space with a huge talent pool and vibrant culture, making it easy for companies to attract employees. In addition, he said that Germany and the German government are open to blockchain technology
in 2014, Germany became the first country to accept bitcoin as a currency, highlighting its open attitude. Similarly, board members of the Bundesbank have called for effective and appropriate regulation of cryptocurrencies and tokens. In fact, Joachim wuermeling, director of the Bundesbank, has pointed out the need for international cooperation on this issue:
to this end, a number of decision makers of the Bundesbank have participated in discussions involving the whole EU region, including stimulating the cryptocurrency instry in the whole EU region through the European block chain partnership "Scientists and engineers in the instry, many of them retired members of Israel's elite military intelligence forces, have transferred to fill the huge talent demand of the instry, and are supported by more and more blockchain start-ups and supporting ecosystems." -
"because the regulatory capacity of a single country is obviously limited, only by maximizing the potential of international cooperation can virtual currency be effectively regulated."
The 
Ethereum mining
Berlin hard fork will mark the end of the metropolitan era. This is a key stage in Ethereum's history, which is divided into two stages (Byzantine and Constantinople), including several branches, including Atlantis, Istanbul, and finally reached its peak in Berlin
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among these experiments, the measurements made by Albert Michelson and ediward Murray at the case Institute in Cleveland, Ohio in 1887 are the most accurate and detailed. They compared the propagation speed of two beams of light at right angles. Due to the rotation around the axis of rotation and the revolution around the sun, according to the reasoning, the earth should travel through the "Ether". Therefore, the above two beams of light at right angles should be measured at different speeds e to the movement of the earth. Murray found that there was no difference in the speed of the two beams of light, whether day and night or winter and summer. Whether you're moving or not, light always seems to travel at the same speed relative to you<
Irish physicist George Fitzgerald and Dutch physicist Hendrick Lorentz first believed that the size of an object moving relative to the "Ether" would shrink in the direction of motion, while the clock moving relative to the "Ether" would slow down. As for "Ether", both Fitzgerald and Lorentz thought it was a real matter at that time
at this time, a young man named Albert Einstein, who works in the Swiss patent office in Bern, Switzerland, intervened in the "Ether" theory and solved the problem of light propagation speed once and for all
in his 1905 article, Einstein pointed out that the whole concept of "Ether" is superfluous because you can't detect whether you are moving relative to "Ether". On the contrary, Einstein believed that the laws of science should have the same form for all free moving observers. No matter how they move, they should measure the same speed of light< This idea of Einstein requires people to give up the universal concept of time measured by all clocks. As a result, everyone has his own time value: if two people are relatively static, then their time is the same; If there is mutual movement between them, the time they observe is different< A large number of experiments have proved that Einstein's idea is correct. An accurate clock rotating around the earth is different from the accurate clock stored in the laboratory in time indication. If you want to prolong your life, you can fly eastward by plane, which can be superimposed with the speed of the earth's rotation. No matter what, you can get a life extension of a few tenths of a second, which can also make up for the damage caused by your eating aviation food< According to Einstein, the premise that all observer's natural laws of free motion are the same is the basis of relativity. The reason for this is that only relative motion is important. Although many scientists and philosophers are convinced by the perfection and simplicity of the theory of relativity, there are still many contrary opinions. Einstein abandoned the two absolute concepts of Natural Science in the 19th century: the absolute stillness implied by "Ether" and the absolute or universal time measured by all clocks. People can't help asking: does relativity imply that everything is relative and there will no longer be an absolute standard in concept
this uneasiness lasted from 1920s to 1930s. In 1921, Einstein won the Nobel Prize in physics for his contribution to the photoelectric effect. However, e to the complexity and controversy of the theory of relativity, the Nobel Prize did not mention the theory of relativity
up to now, I still get two or three letters a week telling me Einstein was wrong. However, now the theory of relativity is fully accepted by the scientific community, and its prediction has been confirmed by numerous experiments
an important result of relativity is the relationship between mass and energy. Einstein's assumption that the speed of light is the same for all observers implies that there is nothing that can run faster than the speed of light. What happens if particles or spaceships are constantly supplied with energy? The mass of the object to be accelerated will increase, making it difficult to accelerate any faster. It is impossible to accelerate a particle to the speed of light, because it requires infinite energy. The equivalence relationship between mass and energy was summarized by Einstein in his famous mass energy equation "E = MC2 & quot; This is probably the only physical equation that can be known to people on the street
when a uranium nucleus splits into two small nuclei, a huge amount of energy will be released e to a small mass loss. This is one of the results of the mass energy equation. In 1939, when the Second World War was in full swing, a group of scientists who realized the application of fission reaction convinced Einstein to overcome his fear of being a pacifist and write to then US President Franklin Delano Roosevelt, persuading the United States to start its nuclear research program, which led to the Manhattan Project and the explosion of the atomic bomb over Hiroshima in 1945. Some people blame Einstein for discovering the mass energy relationship because of the atomic bomb, but this kind of blame is like blaming Newton for discovering gravitation because of the plane crash. Einstein was not involved in any of the Manhattan projects and was terrified by the huge explosion
although relativity is perfectly combined with the relevant laws of electromagnetic theory, it is incompatible with Newton's law of gravity. Newton's gravity theory shows that if you change the distribution of matter in space, the change of gravity field in the whole universe occurs at the same time, which not only means that you can send signals faster than the speed of light (which is not allowed by relativity), but also requires absolute or universal concept of time, which is abandoned by relativity<
Einstein knew this incompatibility difficulty from 1907, when he was still working in the patent office in Bonn, but it was not until 1911, when Einstein was working in Prague, Germany, that he thought deeply about this problem. Einstein realized the close relationship between acceleration and gravity field. The person in the sealed chamber can't tell whether his pressure on the floor is caused by the gravity field of the earth or by the acceleration of the rocket in the non gravitational space All this happened before the age of Star Trek, when Einstein thought of people in elevators rather than spaceships. But we know that if you don't want the elevator collision to happen, you can't accelerate or fall freely in the elevator for a long time.) if the earth is completely flat, people can say that the apple fell on Newton's head e to gravity, which is equivalent to Newton's head hitting the apple e to Newton's accelerating rise with the earth's surface. However, the equivalence between acceleration and gravity is no longer true on the premise that the earth is round, because people on the opposite side of the earth will be accelerated in reverse, but the distance between the two observers remains unchanged< When he returned to Zurich, Switzerland in 1912, Einstein was inspired and realized that if some adjustments were introced into real geometry, the equivalence between gravity and acceleration could be established. Einstein imagined that if the space-time entity formed by three-dimensional space and the fourth dimensional time is curved, what is the result? His idea is that mass and energy will cause the curvature of time and space, which may have been proved in some ways. Like planets and apples, objects tend to move in straight lines, but their tracks seem to be bent by gravity, because space-time is bent by gravity
with the help of his friend Marshall gelusman, Einstein learned the theory of curved space and surface. When Bernhard Riemann developed these abstract theories, he never thought they would be connected with the real world. In 1913, in an article published jointly by Einstein and gelusman, they put forward an idea: the gravity we know is only an expression of the fact that space and time are curved. However, e to one of Einstein's mistakes (Einstein was a real man and would make mistakes), they failed to find out the relationship between the curvature of space-time curvature and the energy mass contained in it
while in Berlin, Einstein continued to work on this issue. He was free from the troubles of his family and was largely unaffected by the war. In November 1915, Einstein finally found the relationship between the curvature of space-time and the energy mass contained in it. During his visit to Gottingen University in the summer of 1915, Einstein discussed this idea with mathematician David Hilbert, who found the same equation a few days earlier than Einstein. Nevertheless, as Hilbert acknowledged, the credit for this new theory belongs to Einstein, who linked gravity to curved spacetime. Thanks also to civilized Germany, because it was there that such scientific discussions and exchanges could still be carried out without any influence ring the war. What a contrast to what happened 20 years later
the new theory of curved space-time is called "general relativity" to distinguish it from the original theory without gravity, and that theory is renamed "special relativity". In 1919, "general relativity" was proved in a rather spectacular form: a British scientific expedition to West Africa at that time observed the tiny movement of the position of a star near the sun in the sky ring the solar eclipse. As Einstein predicted: the light emitted by the star, when passing near the sun, e to the sun's gravity and bending. This is a direct proof of the curvature of time and space. Since Euclid finished his original in 300 BC, this is the biggest revolutionary update of human perception of their existence in the universe
Einstein's "general relativity" transforms "space-time" from a passive event background to an active participant in the dynamic universe, which leads to a huge difficulty in the forefront of science, which remains unsolved at the end of the 20th century. The universe is full of matter, which in turn leads to the bending of space-time and makes objects gather together. When explaining the static universe with general relativity, Einstein found that his equation had no solution. In order to adapt his equation to the static universe, Einstein added a new equation called "general relativity"“
since the revival of the wave theory of light in the early 19th century, physicists have been talking about the light medium ether, one of the important issues is the relationship between ether and measurable matter (especially the earth)< At that time, there were two opposing views. In 1818, Fresnel believed that the earth is made up of extremely porous material, in which the movement of ether is almost unimpeded. Because the refractive index of the air on the earth's surface is close to 1, it can't or can only drag the ether very weakly< According to Stokes, Fresnel's theory is based on the fact that all objects are transparent to the ether, so it cannot be tolerated. He proposed in 1845 that on the surface of the earth, the ether has the same speed as the earth, that is, the earth completely tows the ether. Only at a certain height above the surface of the earth can the ether be considered static. Since Fresnel's theory of static ether can satisfactorily explain the phenomenon of aberration of light (the apparent positions of stars will change in a year e to the revolution of the earth), people generally agree with it
if the theory of static ether is correct, then because the earth's revolution speed is 30 kilometers per second, there should be "yitaifeng" on the earth's surface. Over the years, people have done a series of optical and electrical experiments (the so-called "etheric drift" experiment) in an attempt to measure the relative motion of the earth through the ether. However, e to the limitation of experimental accuracy, we can only measure the first-order quantity of the ratio of the earth's revolution speed to the speed of light, and all these first-order experiments give negative results
with the development of Maxwell's electromagnetic theory, it is known that the effect related to the square of the ratio of the earth's revolution speed to the speed of light should be detected in optical and electrical experiments. Because Maxwell's theory implies that there is a superior reference frame for optical and electrical phenomena, that is, the reference frame in which the ether is stationary, and the second-order effect of ether drift should exist. However, the accuracy of this experiment is too high to be realized< In fact, Maxwell pointed out as early as 1867 that the experiment of measuring the speed of light was carried out on the earth. Because light travels in the same path, the influence of the earth's motion on the ether is only manifested in the second-order effect. In 1879, Maxwell proposed a plan to measure the relative speed of the solar system relative to the ether in a letter to the U.S. Nautical Almanac office, which was adopted by Michelson, who worked in the office at that time< In 1881, Michelson was studying under Helmholtz in Berlin, Germany. Unable to complete the experiment in Berlin, Michelson transported the entire device built for him to the Potsdam Astrophysical Observatory for experiments. His expected displacement is 0.1 of the interference fringe, but the actual measured displacement is only 0.004 ~ 0.005, which is only equivalent to the experimental error
obviously, the negative result (also known as "zero result") indicates that the attempted Ethernet stream does not exist. Faced with the facts, Michelson has to think: "the hypothesis of static ether is proved to be incorrect, and an inevitable conclusion can be obtained: the hypothesis is wrong", "this conclusion is directly contradictory to the explanation of aberration phenomenon which has been generally accepted so far", "he can not be inconsistent with the abstract of Stokes' paper published in the Journal of Philosophy in 1846"< However, the accuracy of this experiment is not high enough, and the data calculation is also wrong. In the winter of 1881, Poitier in Paris pointed out the errors in calculation (the effect of estimation was twice as great as that of reality), and Lorenz also pointed out these problems in 1884. So neither Michelson nor anyone else saw the experiment as decisive. Since then, Michelson himself has also shifted his interest to the precise measurement of the speed of light, and the improvement of the 1881 experiment has been shelved< In the autumn of 1884, William Thomson visited the United States and gave many speeches in Baltimore. Michelson, who attended the lecture, had the opportunity to meet with Lord Rayleigh, who visited the United States with Thomson. They exchanged views on the 1881 experiment. At the same time, Riley also conveyed Lorenz's opinion. Rayleigh's advice to Michelson with great courage, he further improved the interferometer, and the famous chemistry professor Murray together, in July 1887 in Cleveland to carry out the experiment again, at this time Michelson is Cleveland City Case Institute of Applied Sciences Professor
in order to maintain stability and rece the influence of vibration, Michelson and Murray installed the interferometer on a heavy stone plate, suspended the stone plate on the mercury surface, and could rotate smoothly around the central support axis. In order to enlarge the light path as much as possible, they installed several mirrors on the stone slab to make the sodium beam go back and forth eight times, even though the interferometer's arm length was up to 11 meters. According to the calculation, the movement of the interference fringes should be 0.37, but the measured value is less than 0.01
Michelson and Murray believe that if there is relative motion between the earth and the ether, then the relative velocity may be less than 1 / 60 of the earth's revolution speed, and certainly less than 1 / 40. "There seems to be reason to believe that even if there is relative motion between the earth and the ether, it must be small enough to completely refute Fresnel's explanation of aberration," they said in their experimental report
the negative result of the 1887 experiment was puzzling for everyone at that time, and it remained the same for a long time. People didn't think the experiment was decisive. Even Michelson himself was disappointed with his results. He called his experiment a "failure" and gave up the promise he made in the experiment report (measuring six hours every five days and repeating for three months in order to eliminate all the uncertainty). He didn't want to make long-term observation, And the interferometer is used for other things
Michelson doesn't think his experimental results are of great significance. He thinks that the reason why the experiment is meaningful is that he designed a sensitive interferometer to comfort himself. Until his later years, he told Einstein that his own experiment had caused such a "monster" as the theory of relativity. He was really a little regretful<
Lorentz was also unhappy about the results of Michelson's experiment. In his letter to Rayleigh in 1892, he said, "I don't know how to get rid of this contradiction now, but I still believe that if we have to abandon Fresnel's theory,... We won't have a suitable theory at all.". Lorenz is still suspicious of the results of the 1887 experiment: "is there still something that has been overlooked in Mr. Michelson's experiment so far?"<
in a paper in 1892, Rayleigh thought: "is the ether on the surface of the earth absolutely static or relatively static?" The issue is still up in the air. He felt that the negative result Michelson got was "a real disappointment", and urged Michelson to do another experiment. Until the beginning of this century, William Thomson was not reconciled to the negative results of the experiment
by the way, there is no direct connection between Michelson's experimental work and Einstein's theory of relativity in history. But around 1900, his "etheric drift" experiment had an undoubted influence on Lorentz's electron theory. Although the academic circles still have different views on the historical role of the experiment, Michelson himself still remembers "lovely ether" in his later years. Until 1927, when he mentioned in his last book that the theory of relativity had been accepted, he still had many doubts about the new theory< The Michelson Morey experiment seems to exclude Fresnel's static ether theory, which is not only required by the electromagnetic theory, but also supported by the aberration of light and the Fizeau experiment. In order to get rid of this troublesome dilemma, Fitzgerald and Lorenz independently put forward the so-called "contraction hypothesis" in 1889 and 1892 respectively
they believe that because the tube of the interferometer is shortened by one billionth of the linearity in the direction of motion, the displacement of the interference fringes caused by the earth passing through the static ether is compensated, and the negative result is obtained. Based on the electron theory, Lorentz thinks that the contraction is a real dynamic effect, which has universal significance for matter. Ramo also agreed with this view. He proved that if matter is composed of electrons, this can happen.
Michelson's name is associated with Michelson interferometer and Michelson Murray experiment. In fact, it is also Michelson's most important contribution in his life. In Michelson's time, people thought that light and all electromagnetic waves must be transmitted by means of absolutely static "Ether", and whether "Ether" existed and whether it had the characteristics of static was still a mystery at that time. Some people try to measure the "yitaifeng" caused by the movement of the earth to the static "Ether" to prove the existence of ether and its static characteristics. However, e to the limited accuracy of the instrument, they encounter difficulties. Maxwell wrote to D.P. Todd of the U.S. almanac office in 1879, suggesting that Romer's astronomical method be used to study this problem. When Michelson knew this, he decided to design a method to increase the sensitivity to one in a billion, and detect the effects related to it< In 1881, he worked in Helmholtz Laboratory of Berlin University, for which he invented a high-precision Michelson interferometer and carried out the famous experiment of ether drift. He thinks that if the earth revolves around the sun and moves relative to the ether, it will take different time for light to pass through the same distance in the direction parallel to and perpendicular to the earth, so it will take 90 minutes for the instrument to rotate ° 04 fringes will move in the two times. Michelson experimented with the interferometer which was originally built. The optical part of the interferometer was sealed on the platform with wax. It was very inconvenient to adjust. It often took several hours to measure a data. The experimental results are negative< In 1884, with the encouragement of Rayleigh and Kelvin who visited the United States, he cooperated with the chemist Morley (1838-1923) to improve the sensitivity of the interferometer, and the result was still negative. In 1887, they continued to improve the instrument, increasing the light path to 11 meters. They spent five days carefully observing the relative motion between the earth's orbit and the static ether. The result is still negative. This experiment caused scientists' shock and concern, and was called "two dark clouds in the history of science" together with the "ultraviolet disaster" in thermal radiation. More than 10 people then repeated the experiment for 50 years. The further study of it leads to the new development of physics. Another important contribution of Michelson is the measurement of the speed of light. As early as he worked in the Naval Academy, he became interested in measuring the speed of light e to the practical needs of navigation< In 1879, the speed of light was measured. He was the fourth to measure the speed of light on the ground after fizzo, Foucault and Cornell. He received a grant from his father-in-law and government funding, which enabled him to improve the experimental device. He replaced the rotating mirror in Foucault's experiment with a regular octagonal steel prism, thus extending the light path by 600 meters. The displacement of the return light is 133 mm, which improves the accuracy and Foucault's method. He has been measuring the speed of light for many times and continuously. The most accurate measurement was carried out in 1924-1926 on the 22 mile long light path between the mountains of Southern California, with the value of (299796 ± 4km/s Michelson never satisfied with the accuracy he had achieved. He always improved, experimented repeatedly, worked tirelessly, and kept improving. It took half a century. Finally, in a well-designed process of measuring the speed of light, he died of a stroke. Later, his colleagues published the measurement results.
Michelson's name is associated with Michelson interferometer and Michelson Morey experiment. In fact, it is also Michelson's most important contribution in his life. In Michelson's time, people thought that light and all electromagnetic waves must be transmitted by means of absolutely static "Ether", and whether "Ether" existed and whether it had the characteristics of static was still a mystery at that time. Some people try to measure the "yitaifeng" caused by the movement of the earth to the static "Ether" to prove the existence of ether and its static characteristics. However, e to the limited accuracy of the instrument, they encounter difficulties. Maxwell wrote to D.P. Todd of the U.S. almanac office in 1879, suggesting that Romer's astronomical method be used to study this problem. When Michelson knew this, he decided to design a method to increase the sensitivity to one in a billion, and detect the effects related to it< In 1881, he worked in Helmholtz Laboratory of Berlin University, for which he invented a high-precision Michelson interferometer and carried out the famous experiment of ether drift. He thinks that if the earth revolves around the sun and moves relative to the ether, it will take different time for light to pass through the same distance in the direction parallel to and perpendicular to the earth, so it will take 90 minutes for the instrument to rotate ° 04 fringes will move in the two times. Michelson experimented with the interferometer which was originally built. The optical part of the interferometer was sealed on the platform with wax. It was very inconvenient to adjust. It often took several hours to measure a data. The experimental results are negative. Michelson interferometer is a precision optical instrument designed and manufactured by American physicist Michelson and Murray in 1883 to study "Ether" drift. It uses the amplitude division method to generate two beams to realize the interference. By adjusting the interferometer, equal thickness interference fringes and equal inclination interference fringes can be proced. It is mainly used for the measurement of length and refractive index. If the interference fringes move one by one, it means that the arm movement of M2 is λ/ 2, equivalent to the change of air film thickness between M1 and M2 λ/ 2 It has important applications in modern physics and modern metrology, such as the study of fine structure of spectral lines and the calibration of standard meter with light wave. Based on the principle of the instrument, a variety of special interferometers have been developed. The interference fringes are the trajectories of equal optical path difference. Therefore, in order to analyze the pattern proced by certain interference, it is necessary to find out the function of the position distribution of optical path difference of coherent light. If the interference fringes move, the optical path difference corresponding to the field point must change. The reason for the change of optical path difference may be the change of light length L, the change of refractive index n of some medium in the optical path, or the change of film thickness E
since the revival of the wave theory of light in the early 19th century, physicists have been talking about the light medium ether, one of the important issues is the relationship between ether and measurable matter (especially the earth)< At that time, there were two opposing views. In 1818, Fresnel believed that the earth is made up of extremely porous material, in which the movement of ether is almost unimpeded. Because the refractive index of the air on the earth's surface is close to 1, it can't or can only drag the ether very weakly< According to Stokes, Fresnel's theory is based on the fact that all objects are transparent to the ether, so it cannot be tolerated. He proposed in 1845 that on the surface of the earth, the ether has the same speed as the earth, that is, the earth completely tows the ether. Only at a certain height above the surface of the earth can the ether be considered static. Since Fresnel's theory of static ether can satisfactorily explain the phenomenon of aberration of light (the apparent positions of stars will change in a year e to the revolution of the earth), people generally agree with it
if the theory of static ether is correct, then because the earth's revolution speed is 30 kilometers per second, there should be "yitaifeng" on the earth's surface. Over the years, people have done a series of optical and electrical experiments (the so-called "etheric drift" experiment) in an attempt to measure the relative motion of the earth through the ether. However, e to the limitation of experimental accuracy, we can only measure the first-order quantity of the ratio of the earth's revolution speed to the speed of light, and all these first-order experiments give negative results
with the development of Maxwell's electromagnetic theory, it is known that the effect related to the square of the ratio of the earth's revolution speed to the speed of light should be detected in optical and electrical experiments. Because Maxwell's theory implies that there is a superior reference frame for optical and electrical phenomena, that is, the reference frame in which the ether is stationary, and the second-order effect of ether drift should exist. However, the accuracy of this experiment is too high to be realized< In fact, Maxwell pointed out as early as 1867 that the experiment of measuring the speed of light was carried out on the earth. Because light travels in the same path, the influence of the earth's motion on the ether is only manifested in the second-order effect. In 1879, Maxwell proposed a plan to measure the relative speed of the solar system relative to the ether in a letter to the U.S. Nautical Almanac office, which was adopted by Michelson, who worked in the office at that time< In 1881, Michelson was studying under Helmholtz in Berlin, Germany. Unable to complete the experiment in Berlin, Michelson transported the entire device built for him to the Potsdam Astrophysical Observatory for experiments. His expected displacement is 0.1 of the interference fringe, but the actual measured displacement is only 0.004 ~ 0.005, which is only equivalent to the experimental error
obviously, the negative result (also known as "zero result") indicates that the attempted Ethernet stream does not exist. Faced with the facts, Michelson has to think: "the hypothesis of static ether is proved to be incorrect, and an inevitable conclusion can be obtained: the hypothesis is wrong", "this conclusion is directly contradictory to the explanation of aberration phenomenon which has been generally accepted so far", "he can not be inconsistent with the abstract of Stokes' paper published in the Journal of Philosophy in 1846"< However, the accuracy of this experiment is not high enough, and the data calculation is also wrong. In the winter of 1881, Poitier in Paris pointed out the errors in calculation (the effect of estimation was twice as great as that of reality), and Lorenz also pointed out these problems in 1884. So neither Michelson nor anyone else saw the experiment as decisive. Since then, Michelson himself has also shifted his interest to the precise measurement of the speed of light, and the improvement of the 1881 experiment has been shelved< In the autumn of 1884, William Thomson visited the United States and made many speeches in Baltimore. Michelson, who attended the lecture, had the opportunity to meet with Lord Rayleigh, who visited the United States with Thomson. They exchanged views on the 1881 experiment. At the same time, Riley also conveyed Lorenz's opinion. Rayleigh's advice to Michelson with great courage, he further improved the interferometer, and the famous chemistry professor Murray together, in July 1887 in Cleveland to carry out the experiment again, at this time Michelson is Cleveland City Case Institute of Applied Sciences Professor
in order to maintain stability and rece the influence of vibration, Michelson and Murray installed the interferometer on a heavy stone plate, suspended the stone plate on the mercury surface, and could rotate smoothly around the central support axis. In order to enlarge the light path as much as possible, they installed several mirrors on the stone slab to make the sodium beam go back and forth eight times, even though the interferometer's arm length was up to 11 meters. According to the calculation, the movement of the interference fringes should be 0.37, but the measured value is less than 0.01
Michelson and Murray believe that if there is relative motion between the earth and the ether, then the relative velocity may be less than 1 / 60 of the earth's revolution speed, and certainly less than 1 / 40. "There seems to be reason to believe that even if there is relative motion between the earth and the ether, it must be small enough to completely refute Fresnel's explanation of aberration," they said in their experimental report
the negative result of the 1887 experiment was puzzling for everyone at that time, and it remained the same for a long time.