100 must-read books for college students

Chapter 77 The Greatest Discovery of Modern Physics

Chapter 76 The greatest discovery of modern physics: "A Brief Introduction to Special and General Relativity"

Einstein's theory of relativity ushered in a new era of physics, and its impact on people's thoughts and lives in the 20th century is unrivaled.

Estimated.Perhaps, Paul Oherse's words will be recognized by everyone: "For the historical role of Einstein's theory, use'

The word 'impact' is not enough, the theory he proposed was 'transformative', and the atomic age was born of his theory.He Will

Where it will lead mankind, we cannot predict. "

Studying physics and founding the theory of relativity

Albert Einstein (1879-1955) was a theoretical physicist, mathematician, and founder of the theory of relativity.

At the end of the 19th century and the beginning of the 20th century, great achievements were made in the natural sciences. Electronic theory and quantum physics were established one after another.

revolutionized modern physics.At the same time, Riemannian geometry also appeared in the field of mathematics, breaking the long-term dominant Euclidean geometry.
Reedian geometry.All these laid a solid foundation for Einstein to create the theory of relativity. In 1902, Einstein began to
conduct physics research. In 1905, Einstein proposed the special theory of relativity, which had a great impact at that time, but Einstein

Stein believed that special relativity still had certain flaws, so he decided to further develop the theory of relativity. 1915
In [-], Einstein finally established the general theory of relativity after in-depth and assiduous research.After the theory of relativity was put forward, love
In order to let more people understand the thought of relativity, Einstein edited and published three of his papers. This is his famous book "Theory of Relativity".

A Brief Introduction to Special and General Relativity.This book was first published in 1916, and the Chinese translation was based on the 1955th edition of London Methuen Publishing Company in 15.
版译
out.Einstein's scientific research achievements in his life are very remarkable. In addition to his contribution to the development of science in the 20th century in terms of relativity,

In addition to his great contributions, he also made great contributions to quantum physics.Einstein's main works are "The Theory of Relativity"
The Significance of "(1923), "A Study of the Theory of Brownian Motion" (1926), "The Builder of the Universe" (1932), "Theoretical Physics
Method" (1933), "The Evolution of Physics" (1938), etc.

"A Brief Introduction to the Theory of Relativity" A Great Revolution in Science

The main text of "A Brief Introduction to Special and General Relativity" is divided into "Special Relativity", "General Relativity", "About the Whole Universe
Some Considerations of the Universe", expounding the basic principles of the theory of relativity. According to the development of natural science and geometry, Einstein,
Criticized Euclidean geometry, but also accepted and used non-Euclidean geometry to establish and demonstrate his theory of relativity.

Special relativity has two basic principles:

The first principle is the principle of relativity, that the laws of physics are the same in all inertial frames, there is no one particular inertia

.The concepts of time and space are relative.Events that appear to one observer to be simultaneous, another to act relative to him

Moving observers do not appear to be simultaneous.The estimate of the time interval between two events by two such observers will be

will be inconsistent, and their measures of distance will also be inconsistent.Assuming two observers moving with relative uniform velocity, the

If the speed of light is the same, then as long as they use different measures for time and space, they can get the same natural laws for phenomena

, and can tell exactly how much this difference is, in other words, each observer has his own set of time-space frames

There is no absolute space-time that is the same for all observers.

The second principle is the principle of constant speed of light, that is, in all inertial frames, the speed of light in vacuum has the same value.And pass

Experiments have proved that the speed of light is the limit of speed, nothing in the universe can move faster than the speed of light

move.The shortening of the moving ruler and the slowing down effect of the moving clock are both the basic properties of the relativity space-time, which have nothing to do with the internal structure of the object

irrelevant.If the speed of the object is much smaller than the speed of light, the mechanics of relativity can explain Newton's mechanics.

After Einstein proposed the theory of special relativity, he saw the limitations of this theory, because it restricted the principle of relativity to two

In an inertial system of relatively uniform motion.Negating the stationary ether as a special coordinate system, this is a great progress, but in fact
The age-old puzzle in classical mechanics has not really been solved: why the inertial frame is special compared to other coordinate systems in physics, both
superior?There is no answer to this from the theory of classical mechanics.Einstein was acutely aware that this is classical mechanics and
"Inherent epistemological flaws" in special relativity.Therefore, expanding the scope of application of the principle of relativity is naturally his
The next goal to strive for.If viewed from the principle of relativity, non-uniform motion (accelerated motion system or non-inertial system) will produce

what result?He gave serious thought to this question and went on to search for a more general theory of physics.he believes relative
Because of the universality of the principle of sex, it is believed that in nature, no experiment can find absolute motion.Between 1905 and 1906, for
In order to extend the principle of relativity to the accelerated motion system, Einstein accepted Mach's point of view and believed that the theory of non-inertial system must be

To include the theory of gravity, and then he identified the problem of gravity as the research goal.

The non-inertial system must include the gravitational theory.

Physicists have long taken for granted that the two masses are equal, without

Theoretically, further study.After a period of serious thinking, Einstein realized that the inertial mass is equal to the gravitational mass

The key to solving the gravitational problem.Based on the equality of two masses, he proposed the famous equivalence principle: a non-
An inertial frame is equivalent to an inertial frame with a uniform gravitational field.In other words, the motion and presence seen by an accelerating system induce

The inertial system of the force field sees exactly the same motion.Einstein said: The hypothesis of perfect equivalence prevents us from saying

Any frame of reference has absolute acceleration, just as the usual theory of relativity (special relativity) prevents us from saying that any system has absolute velocity

same, and it makes it a matter of course that everything falls with moderate acceleration in the gravitational field.

Discovering the "Equivalent Principle" was considered by Einstein to be the happiest thing in his life.

On the basis of the "equivalent principle", he further proposed the "generalized covariance principle": in any frame of reference, physics

The mathematical form of the law is the same.In this way, he extended the principle of relativity from the inertial frame to the non-inertial frame.However, it is by
Since the "generalized covariance principle" is an extension of the relativity principle of the special theory of relativity, Eins called this gravitational theory

"General Relativity".

The general theory of relativity is essentially a gravitational theory, in the region with a gravitational field, the properties of space

Quality no longer obeys Euclidean geometry, but follows non-Euclidean geometry.For example, in the 19th century, the German mathematician Riemann established the Riemann geometry.
Geometry is a kind of non-Euclidean geometry, it

The properties of non-flat spaces are described.Einstein finally chose Riemann's strict non-Euclidean geometry as the space-time model of general relativity

type.He believes that the real material space is not a flat Euclidean space, but a curved Riemannian space.its bending
The degree depends on the geometric distribution of matter in space.Where the density of matter is high, the strength of the gravitational field is also large, and the space-time is curved
sharp.So it makes no sense to think of absolute vacuum as a physical entity.Obviously, matter revealed by general relativity

The relationship between space and time is more profound than the special theory of relativity.Because the nature of space-time depends not only on the motion of matter, but also on
More importantly, it depends on the distribution of the substance itself.This completely negates Newton's absolute space-time view from a new height.For Africa
The general conditions imposed by the space are

is the gravitational law of general relativity; it is not a law of force, but a set of geometrical
pieces.In order to enable readers to better understand Einstein's theory of relativity, here is a brief introduction to Einstein's three
Prophecy and its confirmation.

First, the movement of the perihelion of Mercury's orbit.According to Newton's gravitational theory, planetary orbits are elliptical.

At one focus of the ellipse.Astronomers have long discovered that there is a discrepancy between the calculated values ​​obtained from Newton's theory and the precise observed values.
After taking into account all the influences of other planets on Mercury, in 1859 the French astronomer Le Verrier discovered that the orbit of Mercury

Compared with the theoretical value, the observed value of point motion is 38" faster per century. In 1882, the American astronomer Newcomb re-determined this value per century

Century Fast 43″. (Note: Today’s measured value is 42″.6).According to general relativity, the elliptical orbits of planets around the sun are very slow
rotates slowly in its own plane, so that the perihelion of the planet's orbit moves by an angle for each revolution of the planet, and its

The value is the largest on Mercury, and the calculated value is 43″.03 per century, which is quite close to the observation data. This confirms the generalized phase

The first effect predicted by the theory of relativity.

Second, the deflection of light rays in a gravitational field.According to general relativity, when a ray passes through a gravitational field, its path will be deflected
change. In 1915, Einstein predicted that light rays would be deflected by 1″.7 when passing through the surface of the sun. He hoped that astronomers would use the heliodon
Observations under favorable conditions confirmed his predictions. In 1919, the Royal Society reviewed this important reasoning, for

Two expeditions were sent, one to Sobral in Brazil and the other to Principe Island in West Africa, with the task of photographing

Photo of the total solar eclipse of May 1919, 5, to determine whether the light emitted by the star was deflected by the gravitational field of the sun.
Turn, and compare the difference between the observed value and the value predicted by the theory of relativity.The observation results of the two places were published on November 1919, 11.
Cloth, they confirmed the predictions of general relativity.

The third one, the red shift of the spectral lines is the third effect predicted by the general theory of relativity.Because in a strong gravitational field, the clock will change
slow, so for the gravitational field centered on the sun, the spectral rate of the sun's light passing from the sun's surface to the earth should be

Redshift phenomenon (that is, the frequency becomes lower and the wavelength becomes longer). In 1925, the American astronomer Adams passed the observation of Sirius's dense
Companion

Observations confirmed the red shift of the spectral lines and confirmed Einstein's prediction.

The effects of these three predictions have been fully confirmed scientifically, which fully demonstrates that Einstein's theory of relativity is scientific and correct.

Theory.

The advanced theory makes a sensation in the world

In 1919, the light rays predicted by the general theory of relativity would be bent and deflected by 1.7 arc seconds when passing through the surface of the sun, and the number of total solar eclipse observations

The value confirmed, the general theory of relativity immediately caused a social sensation.Subsequently, many experiments successively confirmed the deduction of general relativity
The test results pushed the reputation of general relativity to the peak.

Undoubtedly, Einstein's "A Brief Introduction to the Special and General Theory of Relativity" is an epoch-making work in the history of human science.
It puts forward a set of brand-new scientific theories, has caused great changes in the history of science, and has had a great impact on the development of the entire human mind.
had a huge and far-reaching impact.

The general theory of relativity and special relativity put forward by Einstein in this book profoundly reveal the essential properties of time and space

, demonstrated the internal connection and unity of time and space; at the same time, it also developed and transformed Newton's mechanics, making it applicable to a wider range of

A wide range of mechanical phenomena reveals the inner connection between mass and energy, as well as the unity of mechanics and electromagnetism.
Propose a new explanation.It has brought people's research on the world to a new stage.General Relativity Became the Modern Universe
one of the foundations of the theory.The theory of relativity is a physical thought

A major revolution in thinking.

(End of this chapter)