In fact, Einstein's theory of relativity focuses more on the establishment of a concept and does not require very complicated calculations. However, it is very difficult to establish a new world view, because many times people are easily swayed by inertial thinking.
Let’s take a look at how Einstein derived this theory that was seriously ahead of its time.
In fact, the discovery process of this theory was mentioned in a speech delivered by Einstein in Kyoto, Japan on December 14, 1922:
The first time I considered relativity The idea of ????principle was probably 17 years ago. I'm not sure where it comes from, but it must have something to do with optical problems with moving objects. Light passes through the etheric sea, and the earth passes through the etheric sea. From the Earth's perspective, the ether is flowing relative to the Earth. However, I could not find any evidence of ether flow in any physics books. This made me want to find any possible way to prove the flow of ether relative to the earth caused by the movement of the earth. When I began to think about this problem, I had no doubt about the existence of the ether or the motion of the earth. So I predicted that if light from a source was properly reflected by a mirror, it should have a different energy depending on whether it was moving in the direction of the Earth's motion or in the opposite direction. Using two thermopiles, I tried to verify this by measuring the difference in heat generated in each thermopile. The idea was the same as in Michelson's experiment, but my understanding of his experiment was not clear at the time.
When I was a student pondering these questions, I was already familiar with the strange results of Michelson's experiment, and I intuitively realized that if we could accept his results as a fact, then thinking that the earth is relatively The idea of ??ether motion is just wrong. This insight actually provided the first path leading to what is now known as the principle of special relativity. I have since come to believe that although the Earth revolves around the Sun, the motion of the Earth cannot be confirmed experimentally using light.
It happened to be around that time that I had the opportunity to read Lorenz's 1895 monograph. Lorentz discussed and managed to completely solve electrodynamics to a first-order approximation, i.e., to second- and higher-order quantities neglecting the ratio of the speed of a moving body to the speed of light. I also began to study the problem of Fizeau's experiment and hypothesized that when the vacuum coordinate system is replaced by the coordinate system of a moving object, the electron equation established by Lorentz is still valid to explain the problem of Fizeau's experiment. In any case, I believed at the time that the Maxwell-Lorentz equations of electrodynamics were sound and that they described the true state of events. Furthermore, the equations hold true in a moving coordinate system, providing an argument known as the constancy of the speed of light. But this invariance of the speed of light is incompatible with the law of speed addition known from mechanics.
Why do these two things contradict each other? I feel that I encounter an unusual difficulty here. I spent almost a year thinking about it, thinking that I would have to make some kind of revision of Lorenz's view, but in vain. I have to admit, this is not an easy mystery to solve.
By chance, a friend who lives in Bern (Switzerland) helped me. It was a nice day. I visited him and what I said to him was probably: "I have been struggling with a problem these days, and no matter how hard I try, I can't solve it. Today, I bring this problem to you." I had many discussions with him. discussions. Through these discussions, it dawned on me. The next day, I visited him again and simply told him: "Thank you. I have completely solved my problem."
My solution is actually related to the concept of time. The point is that there is no absolute definition of time, but rather an inseparable connection between time and signal speed. Using this idea I was able to completely solve for the first time what had previously been an unusual difficulty.
After having this idea, I completed the special theory of relativity in five weeks. I have no doubt that this theory is also very natural from a philosophical point of view. I also realize that it aligns well with Mach's point. Although special relativity is obviously not directly related to Mach's views, as is the problems later solved by general relativity, it can be said to be indirectly related to Mach's analysis of various scientific concepts.
In this way, the special theory of relativity came out.
And then there's general relativity:
The first idea for general relativity occurred two years later—in 1907, under memorable circumstances.
The relativity of motion is limited to relatively uniform motion and does not apply to random motion. I was already dissatisfied with this at the time. I've always wondered secretly if there was some way to remove this restriction.
In 1907, at the request of Mr. Stark, the editor of the Jahrbuch der Radioaktivit?tund Elektronik (Annals of Radioactivity and Electronics), I attempted to summarize the results of the special theory of relativity for the Jahrbuch. I realized then that while all other laws of nature could be discussed in terms of special relativity, this theory could not be applied to the law of gravity. I had a strong desire to try to find out the reason behind this. But achieving this goal is not easy. What I am most dissatisfied with the special theory of relativity is that although this theory can perfectly give the relationship between inertia and energy, it is still completely unclear about the relationship between inertia and weight, that is, the energy of the gravitational field. I think there may be no explanation at all in the special theory of relativity.
I was sitting in a chair at the Patent Office in Bern when an idea suddenly occurred to me: "If a person falls freely, of course he will not feel his own weight."
I Startled. Such a simple imagination brought a huge impact to me, and it was it that pushed me to propose a new gravity theory. My next thought was: "When a person falls, he is accelerating. What he observes is nothing more than what he observes in an accelerating system." From this, I decided to generalize the theory of relativity from the system of uniform motion to acceleration. in the system. I'm expecting this generalization to allow me to solve the problem of gravity. This is because a falling person's inability to feel his or her own weight can be explained by a new additional gravitational field that cancels out the Earth's gravitational field; in other words, because an accelerating system provides a new gravitational force. field.
I was not able to completely solve the problem immediately based on this point of view. It took me eight more years to find the right relationship. But at the same time, I began to partially realize the general basis of this solution.
Mach also insisted that all acceleration systems are equivalent. But this is obviously inconsistent with our geometry, because if accelerated systems are allowed, then Euclidean geometry will not be applicable in all systems. Expressing a law without geometry is like expressing an idea without language. We first have to find a language to express our thoughts. So what are we looking for in this case?
Before 1912, I did not solve this problem. It was during that year that I suddenly realized that there was good reason to believe that Gauss's surface theory might hold the key to this mystery. At the time I realized that Gaussian surface coordinates were extremely important, but I did not know that Riemann had provided a deeper discussion of the foundations of geometry. I happen to recall that when I was a student, I heard about Gaussian theory in a class of a mathematics professor named Geiser. From here I developed my ideas and came up with the concept that geometry must have physical meaning.
When I returned to Zurich from Prague, my good friend and mathematics professor Grossmann was there. When I was at the Patent Office in Bern, it was difficult to obtain mathematical literature, and he was willing to help me. This time, he taught me Ricci theory and then Riemann theory. So I asked him if Riemannian theory could really solve my problem, which was whether the invariance of a curve element could completely determine its coefficients—the coefficients I had been trying to find. In 1913 we co-wrote a paper. But we didn't get the correct equation for gravity in that paper. Although I continued to study the Riemann equation and tried various methods, I just found many different reasons that led me to believe that it simply could not produce the results I wanted.
Two years of painstaking research followed. Then I finally realized there was an error in my previous calculations. So I turned back to invariant theory and tried to find the correct equation of gravity. Two weeks later, the correct equation finally appeared before my eyes for the first time.
Concerning the research I did after 1915, I would like to mention only cosmological questions. This question involves cosmic geometry and time, based on the treatment of boundary conditions in general relativity on the one hand and Mach's view of inertia on the other.
Of course, I don’t know exactly what Mach thought about the relativity of inertia, but he certainly had at least one extremely important influence on me.
Anyway, after trying to find the invariant boundary conditions for the equation of gravity, I was finally able to solve the cosmological problem by treating the universe as a closed space and eliminating the boundaries. From this I conclude that inertia is nothing more than a property shared by some objects. If there are no other celestial bodies next to a particular object, its inertia will definitely disappear. This, I believe, makes general relativity epistemologically satisfactory.
It can also be seen from Einstein’s description that the introduction of these two theories was not all at once, but a theory derived bit by bit from some experiments and ideas. Its birth is also supported by considerable physical foundation.
Posterity’s evaluation of Einstein
Posterity believes that Einstein was a peace-loving man who also tried his best throughout his life to make great contributions to world peace. Because Einstein burned all his research efforts before his death, some close relatives and friends said that Einstein did this to avoid war and to prevent some people with ulterior motives from using his research data to create weapons.
In fact, when Einstein was alive, European scientists also had a very positive evaluation of Einstein. They all believed that Einstein had done work that no one before him could do. Although Einstein There were some minor mistakes in his later years, but overall his contribution to all mankind cannot be ignored by anyone. He created the three laws, changed people's worldview and values, and changed subsequent technology.
Some people’s evaluation of Einstein focuses on his character. Many experts believe that he was a low-key and introverted person and a maverick. In his will, he asked the world to Don't worship him as a god, and don't turn his former residence into a museum for future generations to admire. It seems that this scientific giant did not want to be disturbed by too many people after his death, nor did he want his death to have a negative impact on people. cause impact.