The theory of relativity was introduced by Albert Einstein at the beginning of the 20th century. What is its essence? Let us consider the main points and characterize the TOE in an understandable language.

The theory of relativity practically eliminated the inconsistencies and contradictions of physics of the 20th century, forced to radically change the idea of ​​the structure of space-time and was experimentally confirmed in numerous experiments and studies.

Thus, TOE formed the basis of all modern fundamental physical theories. In fact, this is the mother of modern physics!

To begin with, it is worth noting that there are 2 theories of relativity:

• Special Relativity (SRT) - considers physical processes in uniformly moving objects.
• General Relativity (GR) - describes accelerating objects and explains the origin of such phenomena as gravity and existence.

It is clear that SRT appeared earlier and, in fact, is a part of GRT. Let's talk about her first.

STO in simple words

The theory is based on the principle of relativity, according to which any laws of nature are the same with respect to stationary and bodies moving at a constant speed. And from such a seemingly simple thought it follows that the speed of light (300,000 m/s in vacuum) is the same for all bodies.

For example, imagine that you are given a spaceship from the far future that can fly at great speeds. A laser cannon is mounted on the bow of the ship, capable of firing photons forward.

Relative to the ship, such particles fly at the speed of light, but relative to a stationary observer, it would seem that they should fly faster, since both speeds are summed up.

However, this does not actually happen! An outside observer sees photons flying at 300,000 m/s, as if the speed spaceship not added to them.

It must be remembered: relative to any body, the speed of light will be a constant value, no matter how fast it moves.

From this, amazing conclusions follow, such as time dilation, longitudinal contraction, and the dependence of body weight on speed. Read more about the most interesting consequences of the Special Theory of Relativity in the article at the link below.

The essence of the general theory of relativity (GR)

To better understand it, we need to combine two facts again:

• We live in 4D space

Space and time are manifestations of the same entity called "space-time continuum". This is the 4-dimensional space-time with x, y, z and t coordinate axes.

We humans are not able to perceive 4 dimensions in the same way. In fact, we see only projections of a real four-dimensional object onto space and time.

Interestingly, the theory of relativity does not state that bodies change as they move. 4-dimensional objects always remain unchanged, but when relative motion their projections may change. And we perceive this as a slowdown in time, a reduction in size, etc.

• All bodies fall at a constant speed instead of accelerating

Let's do a scary thought experiment. Imagine that you are riding in a closed elevator cabin and are in a state of weightlessness.

This situation could arise only for two reasons: either you are in space, or you are freely falling along with the cabin under the influence of the earth's gravity.

Without looking out of the booth, it is absolutely impossible to distinguish between these two cases. It's just that in one case you fly evenly, and in the other with acceleration. You will have to guess!

Perhaps Albert Einstein himself was thinking about an imaginary elevator, and he had one amazing idea: if these two cases cannot be distinguished, then falling due to gravity is also uniform motion. It's just that uniform motion is in four-dimensional space-time, but in the presence of massive bodies (for example,) it is bent and uniform motion is projected into the usual one for us three-dimensional space in the form of fast motion.

Let's look at another simpler, albeit not entirely correct, example of a two-dimensional space curvature.

It can be imagined that any massive body under itself creates a kind of figurative funnel. Then other bodies flying past will not be able to continue their movement in a straight line and will change their trajectory according to the curves of curved space.

By the way, if the body does not have so much energy, then its movement may turn out to be closed in general.

It is worth noting that from the point of view of moving bodies, they continue to move in a straight line, because they do not feel anything that makes them turn. They just got into a curved space and without realizing it have a non-rectilinear trajectory.

It should be noted that 4 dimensions are bent, including time, so this analogy should be treated with caution.

Thus, in general theory Relativity gravity is not a force at all, but only a consequence of the curvature of space-time. At the moment, this theory is a working version of the origin of gravity and is in excellent agreement with experiments.

Surprising Consequences of General Relativity

Light rays can be bent when flying near massive bodies. Indeed, distant objects have been found in space that “hide” behind others, but the light rays go around them, thanks to which the light reaches us.

According to general relativity, the stronger gravity, the slower time passes. This fact is necessarily taken into account in the operation of GPS and GLONASS, because their satellites have the most accurate atomic clocks that tick a little faster than on Earth. If this fact is not taken into account, then in a day the error of coordinates will be 10 km.

It is thanks to Albert Einstein that you can understand where a library or a store is located nearby.

And, finally, GR predicts the existence of black holes, around which gravity is so strong that time simply stops nearby. Therefore, light entering a black hole cannot leave it (be reflected).

In the center of a black hole, due to the colossal gravitational contraction, an object with an infinitely high density is formed, and this, it seems, cannot be.

Thus, GR can lead to very contradictory conclusions, in contrast to , so the majority of physicists did not accept it completely and continued to look for an alternative.

But she manages to predict a lot successfully, for example, the recent sensational discovery confirmed the theory of relativity and made me remember the great scientist with his tongue hanging out again. Love science, read WikiScience.

The science. The Greatest Theories 1: Einstein. Theory of relativity.

Space is a matter of time.

The science. The Greatest Theories Issue #1, 2015 Weekly

Per. from Spanish – M.: De Agostini, 2015. – 176 p.

© David Blanco Laserna, 2012 (text)

Illustrations provided by:

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Introduction

Einstein lived in an era of revolutions. In the 19th century, advertising conquered the press, in the 1920s it established itself on radio, and a couple of decades later it came to television. For the first time, a man found himself in the face of an informational element and met its powerful shock wave to its full height. In the collective memory forever imprinted are the figures of people raised at that historical moment to the crest of glory: Charlie Chaplin, Marilyn Monroe, Elvis Presley, Albert Einstein ...

We can say that by the end of his life, Einstein was ranked among the secular saints. After two world conflicts that legalized chemical weapons and nuclear attacks, worship of scientific progress bordered on horror. The figure of an absent-minded sage with tousled hair, who stood up for disarmament and preached intellectual humility before the forces of nature, became for the whole disappointed generation a symbol of the last opportunity to resurrect faith in the humanism of science. At the moment when Einstein reached the zenith of his fame, he was 72 years old. By that time, many of his passions had cooled down, except for one - the dream of reconciling quantum mechanics with the theory of relativity. In 1980, access to his private correspondence was opened, and the admirers of the scientist were able to recognize their idol as ordinary person. For some, it was a real discovery that he did not wear socks, smoked a pipe, played the violin and had a number of other non-scientific activities and interests.

In the memory of many, Einstein remained an exemplary citizen and pacifist, an opponent of the First World War, Nazism and McCarthyism, but his personal life could not be called as exemplary.

Time magazine named Einstein the man of the century, and it is hardly possible to remove him from this pedestal. This place belongs to the scientist quite deservedly - as a person who embodies the whole century for us. For us, Einstein is both world wars, this is the nuclear mushroom of Hiroshima, this is the persecution and extermination of the Jews, this is the inexorable growth scientific knowledge and its influence on society, it is Zionism, the paranoia of Senator McCarthy, a collection of aphorisms, the formula E = mc², the dream of world peace ...

Einstein tried to preserve his personal space by writing an autobiography that contained less biographical facts than any other biography ever written in history. On the very first pages, he placed a policy statement, which was later quoted a myriad of times: “The main thing in the life of a person of my warehouse is what he thinks and how he thinks, and not in what he does or experiences.” And yet it is unlikely that this warning can stop human curiosity. We will try to trace the connection between the vicissitudes of life through which the scientist went, and his amazing scientific insights. Perhaps if Einstein had immediately achieved an academic position instead of working eight hours a day at the Swiss patent office, he would have come to the same results. But in itself, the reconstruction of the circumstances in which the scientist actually worked is an extremely fascinating and thought-provoking exercise.

From birth, Einstein was close to the latest technological advances, from electric light bulbs to various devices that his father used in his factory. Illustrating the theory of relativity, the scientist constantly gives examples that refer us to the railway and clock mechanics. During Einstein's childhood and youth Railway became new vehicle. The speed that the trains developed was unheard of at that time. In Bern, Einstein observed how the synchronization of clocks between cities stoked the already fervent Swiss passion for punctuality. Perhaps it was these circumstances that stimulated his imagination and contributed to the emergence of a theory that combined time, incredible speeds, and a constant change in the frame of reference. Later, the secrets of gravity were revealed with the help of another invention, which in Einstein's time was at the pinnacle of technological progress: "What I need to know for sure," the physicist exclaimed, "is what happens to the passengers of an elevator that falls into the void!"

In his first articles, the scientist demonstrated an impeccable command of statistical mechanics and exhausted all the possibilities of the traditional molecular kinetic theory. His work explained the movement of dust particles in a beam of light, blue color the sky and the trembling of pollen in a glass of water. In addition, he gave an explanation for the phenomenon of the photoelectric effect, which occupied the minds of many experimental physicists. However, the main thing was waiting for him ahead. The publication in 1905 of a work on special relativity ushered in the real era of Einstein, with its main legacy - a new way of thinking that became a revelation and inspiration for the next generation of physicists. The scientist himself described this transition as follows: New theory is necessary when, first, we are confronted with new phenomena that old theories cannot explain. But this reason is, shall we say, banal, imposed from outside. There is another reason, no less important. It lies in the desire for simplicity and unification of the premises of the theory within its own framework. Following in the footsteps of Euclid, who deduced all geometry known to us from a handful of axioms, Schnstein extended the scope of his theories to the whole of physics. In fact, the general theory of relativity, formulated in 1915, laid the foundations of modern astronomy. Based on simple hypotheses, such as constant the speed of light, or the assumption that all laws of physics apply equally to all observers regardless of their relative motion, Einstein forever changed our understanding of time, space, and gravity. His scientific imagination has managed to reach such limits, the mere thought of which is breathtaking, from the quantum scale (10 ~ 15 m) to the very edge of visible space (1026 m).

The ability to separate the wheat from the chaff is a special gift. Einstein was born with him. Anyone who has ever struggled with solving problems in physics knows how difficult it can be to fly over chains of equations - like how a football player must see not just a center forward approaching him, but the entire field at once. Outstanding intuition was a characteristic feature of Einstein, and it was thanks to it that he could calculate the moves of nature in advance, while others were lost in the external chaos of experimental results. If there was no other way out, he used the most sophisticated mathematical tools, but still his main talent was the ability to immediately enter into a deep dialogue with reality, from where he brought out something like insights, later found expression using the language of logic.

The grains from which the two great theories of the scientist, the general and special theories of relativity, sprouted, were two mental images that came to him in moments of insight. The first was the image of himself chasing a sunbeam in the dark and at the same time wondering: what will happen when I catch up with him? The second image was of a man falling into an abyss and, as he fell, losing the sense of his own weight. It is believed that the most ambitious project of the great physicist - the construction of the final theory, the sum of premises from which all the laws of physics could be derived - failed precisely because for him there was no intuitive image that could serve as a guiding star.

Einstein's modus operandi (mode of action) contributed to the fact that his figure became polemical: often the scientist's guesses were decades ahead of their experimental evidence, but after the discovery of the solution, the contradiction itself turned into the best confirmation of his correctness. Published in 1919, the news that the trajectory of the rays of light from stars is bent near the Sun, in the blink of an eye lifted the physicist to the heights of glory.

SRT, TOE - under these abbreviations lies the term "theory of relativity", familiar to almost everyone. in plain language everything can be explained, even the saying of a genius, so don't be discouraged if you don't remember school course physics, because in fact everything is much simpler than it seems.

The origin of the theory

So, let's start the course "The Theory of Relativity for Dummies". Albert Einstein published his work in 1905 and it caused a stir among scientists. This theory almost completely covered many gaps and inconsistencies in the physics of the last century, but, in addition, it turned the idea of ​​space and time upside down. It was difficult for contemporaries to believe in many of Einstein's statements, but experiments and studies only confirmed the words of the great scientist.

Einstein's theory of relativity explained in simple terms what people had struggled with for centuries. It can be called the basis of all modern physics. However, before continuing the conversation about the theory of relativity, the question of terms should be clarified. Surely many, reading popular science articles, have come across two abbreviations: SRT and GRT. In fact, they mean somewhat different concepts. The first is the special theory of relativity, and the second stands for "general relativity".

Just about complex

SRT is an older theory that later became part of GR. It can only consider physical processes for objects moving at a uniform speed. A general theory, on the other hand, can describe what happens to accelerating objects, and also explain why graviton particles and gravity exist.

If you need to describe the movement and as well as the relationship of space and time when approaching the speed of light - this can be done by the special theory of relativity. In simple terms, it can be explained as follows: for example, friends from the future gave you a spaceship that can fly at high speed. On the nose of the spaceship is a cannon capable of firing photons at everything that comes in front.

When a shot is fired, relative to the ship, these particles fly at the speed of light, but, logically, a stationary observer should see the sum of two speeds (the photons themselves and the ship). But nothing like that. The observer will see photons moving at a speed of 300,000 m/s, as if the speed of the ship was zero.

The thing is that no matter how fast an object moves, the speed of light for it is a constant value.

This statement is the basis of amazing logical conclusions like slowing down and time distortion, depending on the mass and speed of the object. The plots of many science fiction films and series are based on this.

General theory of relativity

A more voluminous general relativity can also be explained in simple terms. To begin with, we should take into account the fact that our space is four-dimensional. Time and space are united in such a "subject" as "space-time continuum". Our space has four coordinate axes: x, y, z, and t.

But people cannot directly perceive four dimensions, just like a hypothetical flat man living in a two-dimensional world, unable to look up. In fact, our world is only a projection of four-dimensional space into three-dimensional.

An interesting fact is that, according to the general theory of relativity, bodies do not change when they move. The objects of the four-dimensional world are in fact always unchanged, and when moving, only their projections change, which we perceive as a distortion of time, reduction or increase in size, and so on.

The elevator experiment

The theory of relativity can be explained in simple terms with the help of a small thought experiment. Imagine that you are in an elevator. The cabin began to move, and you were in a state of weightlessness. What happened? There can be two reasons: either the elevator is in space, or it is in free fall under the influence of the planet's gravity. The most interesting thing is that it is impossible to find out the cause of weightlessness if there is no way to look out of the elevator cabin, that is, both processes look the same.

Perhaps, after conducting a similar thought experiment, Albert Einstein came to the conclusion that if these two situations are indistinguishable from each other, then in fact the body under the influence of gravity does not accelerate, it is a uniform movement that is curved under the influence of a massive body (in this case, the planet ). Thus, accelerated motion is only a projection uniform motion into three-dimensional space.

illustrative example

Another good example on the topic "Theory of Relativity for Dummies". It is not entirely correct, but it is very simple and clear. If any object is placed on a stretched fabric, it forms a "deflection", a "funnel" under it. All smaller bodies will be forced to distort their trajectory according to the new curvature of space, and if the body has little energy, it may not overcome this funnel at all. However, from the point of view of the moving object itself, the trajectory remains straight, they will not feel the curvature of space.

Gravity "downgraded"

With the advent of the general theory of relativity, gravity has ceased to be a force and is now content with the position of a simple consequence of the curvature of time and space. General relativity may seem fantastic, but it is a working version and is confirmed by experiments.

A lot of seemingly incredible things in our world can be explained by the theory of relativity. In simple terms, such things are called consequences of general relativity. For example, rays of light flying at close range from massive bodies are bent. Moreover, many objects from distant space are hidden behind each other, but due to the fact that the rays of light go around other bodies, seemingly invisible objects are available to our gaze (more precisely, to the gaze of the telescope). It's like looking through walls.

The greater the gravity, the slower time flows on the surface of an object. This applies not only to massive bodies like neutron stars or black holes. The effect of time dilation can be observed even on Earth. For example, satellite navigation devices are equipped with the most accurate atomic clocks. They are in the orbit of our planet, and time is ticking a little faster there. Hundredths of a second in a day will add up to a figure that will give up to 10 km of error in route calculations on Earth. It is the theory of relativity that allows us to calculate this error.

In simple terms, it can be expressed as follows: GR underlies many modern technologies, and thanks to Einstein, we can easily find a pizzeria and a library in an unfamiliar area.

The revolutionary physicist used his imagination, not complex mathematics, to come up with his most famous and elegant equation. Einstein is known for predicting strange but true phenomena, such as slower aging of astronauts in space compared to humans on Earth and changes in the shape of solid objects at high speeds.

But the interesting thing is that if you take a copy of Einstein's original 1905 paper on relativity, it's pretty easy to parse. The text is simple and clear, and the equations are mostly algebraic - any high school student can understand them.

This is because complex mathematics was never Einstein's forte. He liked to think figuratively, to conduct experiments in his imagination and comprehend them until the physical ideas and principles became crystal clear.

Here's how Einstein's thought experiments began when he was only 16 years old, and how they eventually led him to the most revolutionary equation in modern physics.

By this point in Einstein's life, his thinly concealed disdain for his German roots, the authoritarian methods of teaching in Germany, had already played a role, and he was kicked out of high school, so he moved to Zurich in hopes of enrolling in the Swiss Federal Institute of Technology (ETH).

But first, Einstein decided to spend a year of training at a school in the nearby city of Aarau. At this point, he soon found himself wondering what it was like to run next to a beam of light.

Einstein had already learned in physics class what a ray of light is: lots of oscillating electric and magnetic fields moving at 300,000 kilometers per second, the measured speed of light. If he ran close at that speed, Einstein realized, he could see many oscillating electric and magnetic fields near him, as if frozen in space.

But it was impossible. Firstly, stationary fields would violate Maxwell's equations, mathematical laws, which contained everything that physicists knew about electricity, magnetism and light. These laws were (and still are) quite strict: any waves in these fields must move at the speed of light and cannot stand still, bar none.

Worse, stationary fields did not fit in with the principle of relativity that had been known to physicists since the days of Galileo and Newton in the 17th century. Essentially, the principle of relativity says that the laws of physics cannot depend on how fast you are moving: you can only measure the speed of one object relative to another.

But when Einstein applied this principle to his thought experiment, a contradiction arose: relativity dictated that everything he could see moving near a beam of light, including stationary fields, must be something mundane that physicists could create in the lab. But no one has ever seen this.

This problem will worry Einstein for another 10 years, throughout his journey of studying and working at ETH and moving to the capital of Switzerland, Bern, where he will become an examiner at the Swiss patent office. It is there that he will resolve the paradox once and for all.

1904: light measurement from a moving train

It wasn't easy. Einstein tried every solution that came to his mind, but nothing worked. Almost despairing, he began to consider a simple yet radical solution. Maybe Maxwell's equations work for everything, he thought, but the speed of light has always been constant.

In other words, when you see a beam of light passing by, it doesn't matter if its source is moving towards you, away from you, to the side, or somewhere else, and it doesn't matter how fast its source is moving. The speed of light you measure will always be 300,000 kilometers per second. Among other things, this meant that Einstein would never see stationary oscillating fields, since he would never be able to catch a beam of light.

This was the only way Einstein saw to reconcile Maxwell's equations with the principle of relativity. At first glance, however, this solution had its own fatal flaw. He later explained it with another thought experiment: imagine a beam being fired along a railroad embankment while a train is passing by in the same direction at, say, 3,000 kilometers per second.

Someone standing near the embankment would have to measure the speed of the light beam and come up with a standard number of 300,000 kilometers per second. But someone on the train will see the light moving at 297,000 kilometers per second. If the speed of light is not constant, Maxwell's equation inside the car must look different, Einstein concluded, and then the principle of relativity will be violated.

This seeming contradiction kept Einstein thinking for almost a year. But then, one fine morning in May 1905, he went to work with his best friend Michel Besso, an engineer he knew from student years in Zurich. The two men talked about Einstein's dilemma, as they always did. And suddenly Einstein saw the solution. He worked on it all night, and when they met the next morning, Einstein said to Besso, “Thank you. I completely solved the problem."

May 1905: lightning strikes a moving train

Einstein's revelation was that observers in relative motion perceive time differently: it is entirely possible for two events to occur simultaneously from the point of view of one observer, but at different times from the point of view of another. And both observers will be right.

Einstein later illustrated his point with another thought experiment. Imagine that the observer is again standing next to the railway and the train is speeding past him. At the moment when the central point of the train passes the observer, lightning strikes at each end of the train. Since lightning strikes at the same distance from the observer, their light enters his eyes at the same time. It is fair to say that the lightning strikes at the same time.

Meanwhile, another observer sits exactly in the center of the train. From his point of view, the light from two lightning strikes travels the same distance and the speed of light will be the same in either direction. But since the train is moving, the light coming from the rear zipper has to get through greater distance, so it hits the observer a few moments later than the light from the beginning. Since the light pulses arrive at different times, it can be concluded that the lightning strikes are not simultaneous - one occurs faster.

Einstein realized that it is precisely this simultaneity that is relative. And once you admit it, the strange effects that we now associate with relativity are resolved with simple algebra.

Einstein feverishly wrote down his thoughts and submitted his work for publication. The title was On the Electrodynamics of Moving Bodies, and it reflected Einstein's attempt to link Maxwell's equations with the principle of relativity. Besso received a special thanks.

September 1905: mass and energy

This first work, however, did not become the last. Einstein was obsessed with relativity until the summer of 1905, and in September he submitted a second paper for publication, already after the fact, retroactively.

It was based on yet another thought experiment. Imagine an object at rest, he said. Now imagine that it simultaneously emits two identical pulses of light in opposite directions. The object will stay in place, but since each pulse carries a certain amount of energy, the energy contained in the object will decrease.

Now, wrote Einstein, what would this process look like to a moving observer? From his point of view, the object will simply continue to move in a straight line while the two pulses fly away. But even if the speed of the two pulses remains the same - the speed of light - their energies will be different. An impulse that moves forward in the direction of travel will have a higher energy than one that travels in the opposite direction.

Adding a bit of algebra, Einstein showed that for all of this to be consistent, the object must not only lose energy when sending light pulses, but also mass. Or mass and energy must be interchangeable. Einstein wrote down an equation that connects them. And it became the most famous equation in the history of science: E = mc 2 .

Special Theory of Relativity (SRT).

SRT is based on two principles or postulates that do not explain why it should happen in this way and not otherwise. However, the theory built on their acceptance makes it possible to accurately describe the events taking place in the world.

All physical laws must look the same in all inertial frames of reference.

The speed of light in vacuum does not change when the state of motion of the light source changes.

Consequences following from the first principle:

• Not only laws mechanical movement, as it was in classical mechanics, but also the laws of other physical phenomena should look or behave the same in all inertial frames of reference.
• · Everything inertial systems counts are equal. Therefore, there is no preferred frame of reference, whether it be the Earth or the ether.

The concept of ether as an absolute reference system has no physical meaning.

Consequences arising from the second principle:

• · There is no infinitely high speed of distribution of physical interaction in the world.
• · In the physical world, the interaction is not carried out instantly at a speed exceeding the speed of light.

Consequences arising jointly from the two principles of SRT:

• There are no simultaneous events in the world.
• · It is impossible to consider space and time as independent from each other properties of the physical world.

Lorentz transformations have physical meaning. Ruzavin G.I. Concepts of modern natural science: a textbook for universities. - M.: Culture and sport, UNITI, 2006.

The proof of the connection between space and time can be explained by the following example, in which it should be borne in mind that, according to SRT, in all inertial frames of reference, light propagates with the same speed. Suppose that there are two inertial frames of reference that are equal in describing physical events, i.e., each gives objective descriptions: a person standing on a railway platform (caretaker), and a passenger of a train moving at the same speed relative to the platform and a stationary caretaker. Above the passenger's head is an electric light bulb, which flashes at the moment when the passenger, sitting at the window of the car, and the caretaker, standing on the platform, are exactly opposite each other in the direction of the train. Classical mechanics gives the following description of this event.

Time has an absolute meaning, so it does not depend on the spatial movement of events. The caretaker is standing, the passenger is moving, but the rhythm of time is the same for them. SRT gives another solution:

For a passenger in a car, the light will reach both walls of the car at the same time, since in all inertial reference frames the light will travel in all directions at the same speed.

The caretaker will have a different point of view. He will say that the light will reach the back wall (it moves towards the light along the train) before the front wall of the car, since it catches up with it along the train.

Further, if we set in advance the same time on the clocks of the caretaker and the passenger of the train, then for stationmaster the clock at the rear wall of the car will show a different time from the time on the clock face at the front wall. They will show that the light reaches the back wall before the front wall. Therefore, some clocks go faster, others slower. Thus, space and time, according to SRT, are interconnected and are not absolute, as it was with Galileo - Newton, but relative: the speed of the clock depends on its position in space, the position in space affects the speed of the clock.

SRT Disadvantages:

In her we are talking only about inertial frames of reference. But most frames of reference are in real life non-inertial (acceleration and speed change with time).

It does not take into account the effect of gravitational force on light. The search for the elimination of these shortcomings of SRT led to the creation of general relativity.

General Theory of Relativity (GR).

General relativity is based on two principles or postulates:

• The principle of relativity.
• · The principle of equivalence of heavy and inertial body masses.

The first principle states that the laws of physics should have the same form not only in inertial frames, but also in non-inertial frames of reference, i.e., inertial frames of reference should not be considered as privileged frames of reference, as classical mechanics did. Analyzing non-inertial frames of reference moving with the same acceleration, Einstein came to the unexpected conclusion that in these frames a phenomenon arises similar to the phenomenon of gravitation in a uniform gravitational field. A homogeneous gravitational field is a kind of abstraction or idealization. In this field, the gravitational force has the same value in all its directions and at each of its points. Considering this similarity, A. Einstein came to the conclusion that the force of gravity can be created or destroyed by the transition to a reference frame moving with acceleration. For example, if a person is in a windowless elevator outside of gravity, then he will be in a state of weightlessness. All objects around him and he himself will not be attracted to the floor of the elevator. If you mentally pull the elevator up with a rope at a speed equal to the free fall acceleration on Earth, then this person will feel the action of the gravitational force, which will be similar to the gravitational force in a uniform gravitational field, where at each of its points the free fall acceleration of bodies has the same size. Actually from external system counting, it is correct to say that the elevator, its floor, is moving towards the person and objects in it.

The principle of equivalence of heavy and inertial masses. This principle contains the answer to the question that Einstein asked himself: what determines the action of the force of gravity, how is it determined? In Newtonian physics, gravity depends solely on the mass of bodies. From the law of free fall of bodies, discovered by Galileo, it followed that between the heavy and inertial masses of the body there is proportional dependence, which allows us to assume that there is no significant difference between these body masses when we talk about the action of the gravitational force.

Since all the balls fall with the same -acceleration, regardless of their weight, this indicates that the inertial mass of bodies is proportional to their gravitational mass. Relation Mi ? mi (where mi is the inertial mass of any body, Mi is the gravitational mass of the same body) remains constant for all bodies in free fall, regardless of their real physical nature (made of wood or metal, etc.). In 1890, the Hungarian physicist Eötvös experimentally proved the validity of the assumption of Galileo-Newton physics about the proportional inertial and gravitational masses of the body. For Newton, this ratio was less than 10-8 (M1,/m1< 10-8). В дальнейшем эта величина оказалась еще меньше, что позволяет говорить о равенстве, эквивалентности этих масс тела.

Analyzing the physical meaning of the proportional correspondence between the inertial and heavy masses of the body, as well as the nature of the similarity of the action of the gravitational force with the phenomenon that occurs in a non-inertial frame of reference moving with constant acceleration, Einstein came to the conclusion that the gravitational force does not depend on the mass of bodies. Naturally, the question arose: what does it depend on? Einstein gave the following answer to this question: from a theoretical point of view, there are grounds to assert that the force of gravity is equivalent to the curvature of space and the curvature of space is equivalent to the action of the force of gravity. In this solution, the force of inertia, which in Newtonian physics was considered as an unreal force, is given a real status. For example, when a train is moving, passengers observe the apparent movement of objects outside the train in the opposite direction. In Einstein's theory, this force is given real meaning. Suppose there is an elevator, which is fixed on a rope in such a way that the objects located in it are not affected by the force of gravity. Then the objects will be located on the same line relative to the floor of the elevator. At the moment of cutting the rope, an inertia force will arise, which will tend to maintain the initial position of each object in the elevator. Since the gravitational force is directed towards the center of the Earth, the direction of the inertial force for each object of the elevator will not be the same, but will depend on its distance from the center of the elevator. For some objects, it will be directed upwards, where the force of gravity will be perpendicular to the center of the Earth. In other places of the elevator, the direction of the inertial force will be at a certain angle to the direction of the gravitational force. As a result, the space inside the falling elevator will be curved. For an observer outside the elevator, objects will not be located on a straight horizontal line parallel to the floor, but on a curved line. Light in such a space will not propagate in a straight line, as required by SRT, but along a curved line.

Consequences of general relativity.

Light in curved space-time cannot propagate at the same speed, as SRT required. Near the source of gravitational force, it propagates more slowly than away from it.

The rate of the clock slows down when approaching the source of gravity.

In the structure of space - time - energy (substance, field, radiation), formations, structures are possible, where the gravitational force, represented by the corresponding value of the curvature tensor, is so strong that energy cannot escape from this structure, as a kind of "black hole". in the form of light, field and matter. Einstein's gravitational equation includes a 10-component "energy-momentum" tensor to describe the acceleration of a body in a moving medium. Adding to this tensor information (components) about the forces acting in the moving medium itself, where the body is located, gives a system of equations for describing evolutionary processes in the Universe.

Having created general relativity, A. Einstein pointed out three phenomena, the explanations of which by his theory and Newton's theory gave different results: this is the rotation of the plane of Mercury's orbit, the deflection of light rays passing near the Sun, and the red shift of the spectral lines of light emitted from the surface of massive bodies. The effect of turning the plane of Mercury's orbit was discovered by the astronomer Leverrier (1811-1877). Newton's theory did not provide an explanation for this phenomenon. We are talking about the rotation of the plane of the orbit of Mercury around the major axis of the ellipse, along which Mercury moves around the Sun.

According to A. Einstein's General Relativity, the planets, completing a complete revolution around the Sun, cannot return to the same place, but move somewhat forward and their orbits rotate slowly in their plane. This effect was predicted by A. Einstein. The verification of the calculations coincided exactly with the predictions of general relativity. Concepts of modern natural science: a textbook for university students / ed. V.N. Lavrinenko, V.P. Ratnikov. - 4th ed., revised. and additional - M.: UNITY-DANA, 2008.

The idea of ​​creating a theory of gauge fields is closely connected with the development of the theory of general relativity. The German mathematician G. Weil (1862-1943) in his work "Space, Time and Matter" (1918) formulated the principle that physical laws must be invariant (have the same look) concerning change of scales of measurement in systems space - time - substance. The transformation or change in the measurement scales can be both homogeneous and non-homogeneous from one point to another in spatio-temporal structures.

Inhomogeneous transformations are called gauge transformations. In general relativity, the scales of lengths and time do not depend on the place, time and state of motion of the observer. The theory of G. Weyl allows just changes in time scales in spatio-temporal structures.

Curved space can be imagined as follows. If you stretch a thin piece of rubber and place a heavy object in the center of it, the rubber underneath will sag. If now a small ball is rolled along this patch, it will be pulled towards the hollow. If the cavity is deep, then the ball will rotate around the object that formed this cavity.

The first physicist who enthusiastically accepted the discovery of the elementary quantum of action and creatively developed it was A. Einstein. In 1905, he transferred the ingenious idea of ​​quantized absorption and energy release during thermal radiation to radiation in general, and thus substantiated the new theory of light. If M. Planck (1900) quantized only the energy of a material oscillator, then Einstein introduced the concept of a discrete, quantum structure of the light radiation itself, considering the latter as a stream of light quanta, or photons (the photon theory of light). Thus, Einstein owns the theoretical discovery of the photon, experimentally discovered in 1922 by A. Compton.

The notion of light as a stream of fast-moving quanta was extremely bold, almost daring, in the correctness of which few believed at first. First of all, M. Planck himself did not agree with the extension of the quantum hypothesis to the quantum theory of light, referring his quantum formula only to the laws he considered thermal radiation black body.

A. Einstein suggested that we are talking about a natural pattern of a universal nature. Without looking back at the prevailing views in optics, he applied Planck's hypothesis to light and came to the conclusion that the corpuscular structure of light should be recognized. Concepts of modern natural science: a textbook for university students / ed. V.N. Lavrinenko, V.P. Ratnikov. - 4th ed., revised. and additional - M.: UNITY-DANA, 2008.

The quantum theory of light, or photon theory, by A. Einstein argued that light is a wave phenomenon constantly propagating in the world space. And at the same time, light energy, in order to be physically effective, is concentrated only in certain places, therefore light has a discontinuous structure. Light can be viewed as a stream of indivisible energy grains, light quanta, or photons. Their energy is determined by the elementary Planck action quantum and the corresponding number of oscillations. Light of different colors consists of light quanta of different energies.

Einstein's idea of ​​light quanta helped to understand and visualize the phenomenon of the photoelectric effect, the essence of which is to knock electrons out of matter under the influence of electromagnetic waves. Experiments have shown that the presence or absence of the photoelectric effect is determined not by the intensity of the incident wave, but by its frequency. If we assume that each electron is knocked out by one photon, then the following becomes clear: the effect occurs only if the energy of the photon, and, consequently, its frequency, is large enough to overcome the binding forces of the electron with the substance.

The correctness of this interpretation of the photoelectric effect (for this work, Einstein in 1922 received Nobel Prize in physics) after 10 years was confirmed in the experiments of the American physicist R.E. Millikan (1868 - 1953). Discovered in 1923 by the American physicist A.Kh. Compton (1892 - 1962) the phenomenon (Compton effect), which is observed when atoms with free electrons are exposed to very hard X-rays, again and already finally confirmed the quantum theory of light. This theory is one of the most experimentally confirmed physical theories. But the wave nature of light has already been firmly established by experiments on interference and diffraction.

A paradoxical situation arose: it was discovered that light behaves not only like a wave, but also like a stream of corpuscles. In experiments on diffraction and interference, his wave properties, and with the photoelectric effect - corpuscular. In this case, the photon turned out to be a corpuscle of a very special kind. The main characteristic of its discreteness - the portion of energy inherent in it - was calculated through a purely wave characteristic - frequency.

Like all great discoveries in the natural sciences, the new doctrine of light was of fundamental epistemological significance. The old position on the continuity of natural processes, which was thoroughly shaken by M. Planck, Einstein excluded from a much wider area of ​​physical phenomena.

Modern relativistic cosmology builds models of the Universe, starting from the basic equation of gravitation introduced by A. Einstein in the general theory of relativity (GR). Likhin A.F. Concepts of modern natural science: textbook. - M.: TK Velby, Prospekt Publishing House, 2006.

The basic equation of general relativity links the geometry of space (more precisely, the metric tensor) with the density and distribution of matter in space. For the first time in science, the Universe appeared as a physical object. The theory includes its parameters: mass, density, size, temperature.

Einstein's equation of gravitation has not one, but many solutions, which is the reason for the existence of many cosmological models of the Universe. The first model was developed by A. Einstein in 1917. He rejected the postulates of Newtonian cosmology about the absoluteness and infinity of space. According to A. Einstein's cosmological model of the Universe world space uniformly and isotropically, matter is distributed uniformly in it on average, the gravitational attraction of masses is compensated by the universal cosmological repulsion. A. Einstein's model has a stationary character, since the space metric is considered independent of time. The time of existence of the Universe is infinite, i.e. has neither beginning nor end, and space is boundless, but finite.

Universe in cosmological model A. Einstein is stationary, infinite in time and unlimited in space.

This model seemed at that time quite satisfactory, since it was consistent with all known facts. But the new ideas put forward by A. Einstein stimulated further research, and soon the approach to the problem changed decisively.

In the same 1917, the Dutch astronomer W. de Sitter (1872--1934) proposed another model, which is also a solution to the equations of gravitation. This solution had the property that it would exist even in the presence of an "empty" Universe free of matter. If, however, masses appeared in such a Universe, then the solution ceased to be stationary: a kind of cosmic repulsion arose between the masses, tending to remove them from each other. The tendency to expand, according to V. de Sitter, became noticeable only at very large distances.

In 1922, the Russian mathematician and geophysicist A.A. Friedman (1888 - 1925) rejected the postulate of classical cosmology about the stationarity of the Universe and obtained a solution to A. Einstein's equations describing the Universe with an "expanding" space.

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