The theory of relativity is an integral part. Einstein's theory of relativity in simple words. Special theory of relativity

Einstein's theory of relativity has always been something abstract and incomprehensible to me. Let's try to describe Einstein's theory of relativity in simple terms. Imagine you are outside in heavy rain and the wind is blowing on your back. If you start running fast, the rain drops will not fall on your back. Drops will be slower or not reach your back at all, this is a scientifically proven fact, and you yourself can check this in a downpour. Now imagine if you turned around and ran against the wind with rain, the drops would fall harder on your clothes and face than if you just stood.

Previously, scientists thought light acted like rain on windy days. They thought that if the Earth moves around the Sun, and the Sun moves around the galaxy, then it is possible to measure the speed of their movement in space. In their opinion, all that remains for them to do is to measure the speed of light and how it changes relative to two bodies.

Scientists have done this found something very strange. The speed of light was the same, no matter how the bodies moved and no matter in what direction to take measurements.

It was very strange. If we take a rainstorm situation, then under normal circumstances, raindrops will affect you more or less depending on your movements. Agree, it would be very strange if the downpour blew in your back with the same force, both when running and when stopping.

Scientists have discovered that light does not have the same properties as raindrops or anything else in the universe. No matter how fast you are moving, and no matter which direction you are heading, the speed of light will always be the same. This is very confusing and only Albert Einstein was able to shed light on this injustice.

Einstein and another scientist, Hendrik Lorenz, figured out that there is only one way to explain how it all could be. This is only possible if time slows down.

Imagine what would happen if time slowed down for you and you didn't know you were moving slower. You will feel like everything else is happening faster., everything around you will move like in a fast-forward movie.

So now let's pretend you're in a downpour again. How is it possible that the rain will affect you in the same way even if you are running? It turns out that if you tried to run away from the rain, then your time would slow down and the rain would speed up. Raindrops would fall on your back at the same speed. Scientists call this expansion of time. No matter how fast you move, your time slows down, at least for the speed of light, this expression is true.

Duality of measurements

Another thing that Einstein and Lorentz found out is that two people under different circumstances can get different calculated values, and the strangest thing is that they will both be right. It's another one side effect that light always travels at the same speed.

Let's do a thought experiment

Imagine that you are standing in the center of your room and you have placed a lamp right in the middle of the room. Now imagine that the speed of light is very slow and you can see how it spreads, imagine that you have turned on the lamp.

As soon as you turn on the lamp, the light will begin to diverge and illuminate. Since both walls are at the same distance, the light will reach both walls at the same time.

Now imagine that your room has a large window and a friend of yours drives by. He will see something else. To him, it will look like your room is moving to the right, and when you turn on the lamp, he will see the left wall moving towards the light. and the right wall moves away from the light. He will see that the light first hit the left wall, and then the right. It seems to him that the light did not illuminate both walls at the same time.

According to Einstein's theory of relativity, both points of view would be right.. From your point of view, the light hits both walls at the same time. From your friend's point of view, this is not the case. There is nothing wrong.

That's why scientists say that "simultaneity is relative." If you are measuring two things that should happen at the same time, then someone who is moving at a different speed or in a different direction will not be able to measure them the same way as you.

This seems very strange to us, because the speed of light for us is instantaneous, and we move very slowly compared to it. Because the speed of light is so fast, we don't notice the speed of light unless we do special experiments.

The faster an object moves, the shorter and smaller it is

Another very strange side effect that the speed of light does not change. At the speed of light, moving things get shorter.

Again, let's imagine that the speed of light is very slow. Imagine that you are on a train and you have installed a lamp in the middle of the car. Now imagine that you have turned on the lamp, as in the room.

The light will spread and simultaneously reach the walls in front and behind the car. This way you can even measure the length of the wagon by measuring how long it took for the light to reach both sides.

Let's do the calculations:

Imagine that it takes 1 second to travel 10 meters and it takes 1 second for the light to travel from the lamp to the wall of the car. This means that the lamp is located at a distance of 10 meters from both sides of the car. Since 10 + 10 = 20, it means that the length of the car is 20 meters.

Now let's imagine that your friend is on the street, watching the train go by. Remember that he sees things differently. The rear wall of the car moves towards the lamp, while the front wall moves away from it. Thus, for him, the light will not touch the front and back of the wall of the car at the same time. First, the light will reach the back, and then to the front.

Thus, if you and your friend measure the speed of propagation of light from the lamp to the walls, you will get different values, while from the point of view of science, both calculations will be correct. Only for you, according to the measurements, the length of the wagon will be the same size, and for a friend, the length of the wagon will be less.

Remember, it's all about how and under what conditions you measure. If you were inside a flying rocket that moves at the speed of light, you would not feel anything unusual, unlike people on the ground measuring your movement. You wouldn't be able to tell that time was running slower for you, or that the front and back of the ship were suddenly closer together.

At the same time, if you were flying on a rocket, then it would seem to you as if all the planets and stars are flying past you at the speed of light. In this case, if you try to measure their time and size, then logically for them, time should slow down and size decrease, right?

All this was very strange and incomprehensible, but Einstein proposed a solution and combined all these phenomena into one theory of relativity.

Introduction

2. Einstein's general theory of relativity

Conclusion

List of sources used

Introduction

Also in late XIX century, most scientists were inclined to the point of view that the physical picture of the world was basically built and would remain unshakable in the future - only the details had to be clarified. But in the first decades of the twentieth century, physical views changed radically. It was a consequence of the "cascade" scientific discoveries made during an extremely short historical period, covering last years XIX centuries and the first decades of the XX, many of which did not fit into the idea of ​​ordinary human experience. A striking example is the theory of relativity created by Albert Einstein (1879-1955).

For the first time, the principle of relativity was established by Galileo, but it received its final formulation only in Newtonian mechanics.

The principle of relativity means that in all inertial systems all mechanical processes occur in the same way.

When the mechanistic picture of the world dominated in natural science, the principle of relativity was not subjected to any doubt. The situation changed dramatically when physicists came to grips with the study of electrical, magnetic, and optical phenomena. For physicists, the insufficiency of classical mechanics for describing natural phenomena has become obvious. The question arose: is the principle of relativity also valid for electromagnetic phenomena?

Describing the course of his reasoning, Albert Einstein points out two arguments that testified in favor of the universality of the principle of relativity:

This principle is fulfilled with great accuracy in mechanics, and therefore it can be hoped that it will turn out to be correct in electrodynamics as well.

If inertial systems are not equivalent for describing natural phenomena, then it is reasonable to assume that the laws of nature are most simply described in only one inertial system.

For example, consider the movement of the Earth around the Sun at a speed of 30 kilometers per second. If the principle of relativity in this case was not fulfilled, then the laws of motion of bodies would depend on the direction and spatial orientation of the Earth. Nothing like that, ie. physical inequality of different directions was not found. However, here arises the seeming incompatibility of the principle of relativity with the well-established principle of the constancy of the speed of light in a vacuum (300,000 km/s).

A dilemma arises: the rejection of either the principle of the constancy of the speed of light, or the principle of relativity. The first principle is so precisely and unambiguously established that it would be manifestly unjustified to reject it; no less difficulties arise when the principle of relativity is denied in the field of electromagnetic processes. In fact, as Einstein showed:

"The law of the propagation of light and the principle of relativity are compatible."

The apparent contradiction between the principle of relativity and the law of the constancy of the speed of light arises because classical mechanics, according to Einstein, relied on “two unjustified hypotheses”: the time interval between two events does not depend on the state of motion of the reference body and the spatial distance between two points solid body does not depend on the state of motion of the reference body. During the development of his theory, he had to abandon: the Galilean transformations and accept the Lorentz transformations; from the Newtonian concept of absolute space and the definition of the motion of a body relative to this absolute space.

Each movement of the body occurs relative to a certain reference body, and therefore all physical processes and laws must be formulated in relation to a precisely specified reference system or coordinates. Therefore, there is no absolute distance, length, or extent, just as there can be no absolute time.

New concepts and principles of the theory of relativity significantly changed the physical and general scientific ideas about space, time and motion, which dominated science for more than two hundred years.

All of the above justifies the relevance of the chosen topic.

The purpose of this work is a comprehensive study and analysis of the creation of special and general theories of relativity by Albert Einstein.

The work consists of an introduction, two parts, a conclusion and a list of references. The total amount of work is 16 pages.

1. special theory Einstein's relativity

In 1905, Albert Einstein, based on the impossibility of detecting absolute motion, concluded that all inertial frames of reference are equal. He formulated two important postulates that formed the basis new theory space and time, called the Special Theory of Relativity (SRT):

1. Einstein's principle of relativity - this principle was a generalization of Galileo's principle of relativity to any physical phenomena. It says: all physical processes under the same conditions in inertial reference systems (ISF) proceed in the same way. This means that no physical experiments carried out inside a closed IRF can determine whether it is at rest or moving uniformly and rectilinearly. Thus, all IFRs are absolutely equal, and physical laws are invariant with respect to the choice of IFR (ie, the equations expressing these laws have the same form in all inertial frames of reference).

2. The principle of constancy of the speed of light - the speed of light in vacuum is constant and does not depend on the movement of the light source and receiver. It is the same in all directions and in all inertial frames of reference. The speed of light in vacuum - the limiting speed in nature - is one of the most important physical constants, the so-called world constants.

A deep analysis of these postulates shows that they contradict the concepts of space and time accepted in Newton's mechanics and reflected in Galileo's transformations. Indeed, according to principle 1, all laws of nature, including the laws of mechanics and electrodynamics, must be invariant with respect to the same transformations of coordinates and time, carried out during the transition from one frame of reference to another. Newton's equations satisfy this requirement, but Maxwell's equations of electrodynamics do not, i.e. turn out to be invariant. This circumstance led Einstein to the conclusion that Newton's equations needed to be refined, as a result of which both the equations of mechanics and the equations of electrodynamics would turn out to be invariant with respect to the same transformations. The necessary modification of the laws of mechanics was carried out by Einstein. As a result, a mechanics emerged that is consistent with Einstein's principle of relativity - relativistic mechanics.

The creator of the theory of relativity formulated the generalized principle of relativity, which now extends to electromagnetic phenomena, including the motion of light. This principle states that no physical experiments (mechanical, electromagnetic, etc.) carried out within a given frame of reference can distinguish between the states of rest and uniform rectilinear motion. The classical addition of velocities is inapplicable for propagation electromagnetic waves, Sveta. For all physical processes The speed of light has the property of infinite speed. In order to tell a body a speed equal to the speed of light, an infinite amount of energy is required, and that is why it is physically impossible for any body to reach this speed. This result was confirmed by measurements that were carried out on electrons. The kinetic energy of a point mass grows faster than the square of its speed, and becomes infinite for a speed equal to the speed of light.

The speed of light is the limiting speed of propagation of material influences. It cannot add up at any speed and for all inertial systems it turns out to be constant. All moving bodies on Earth in relation to the speed of light have a speed equal to zero. Indeed, the speed of sound is only 340 m/s. It is stillness compared to the speed of light.

From these two principles - the constancy of the speed of light and the extended principle of relativity of Galileo - mathematically follow all the provisions of the special theory of relativity. If the speed of light is constant for all inertial frames, and they are all equal, then physical quantities body length, time interval, mass for different reference systems will be different. So, the length of a body in a moving system will be the smallest in relation to a resting one. According to the formula:

where /" is the length of a body in a moving system with a speed V with respect to a stationary system; / is the length of a body in a resting system.

For a period of time, the duration of a process, the opposite is true. Time will, as it were, stretch, flow more slowly in a moving system in relation to a stationary one, in which this process will be faster. According to the formula:

Recall that the effects of the special theory of relativity will be detected at velocities close to the speed of light. At speeds much less than the speed of light, the SRT formulas turn into the formulas of classical mechanics.

Fig.1. Einstein Train Experiment

Einstein tried to visually show how the flow of time slows down in a moving system in relation to a stationary one. Imagine a railway platform, past which a train passes at a speed close to the speed of light (Fig. 1).

Einstein's theory introduced the following postulates into the understanding of world patterns related to time: - not absolutely, i.e. the simultaneity of events finds meaning in one frame of reference. The course of time depends on movement, therefore it is relative; - space and time make up a four-dimensional world; - gravitational forces affect time: the more, the slower time; - depending on gravity, can change, but only in the direction of decrease; - y a moving body has a reserve of kinetic energy: its mass is greater than the mass of the same body at rest. Einstein, abandoning the Newtonian concept of absolute time, not only proved that time is always relative, but also firmly linked it with gravity and the speed of a body, which depends from the reference system. It was Einstein at the beginning of the twentieth century who was closest to understanding the relativity of time. In accordance with the theory of relativity, the speed of time directly depends on the distance of the object from the center of gravity, as well as the speed of the object. The greater the speed, the shorter the time. For a more understandable disclosure of the relativity of time, one can cite. The person remains in a specially prepared room with one window, and a clock to measure the time spent. If, after a few days, you ask him how long he stayed in this room, then his answer will depend on the calculation of sunsets and sunrises and on the clock, which he always looked at. In his calculations, for example, he stayed in the room for 3 days, but if you tell him that the sun was fake, and the clock was in a hurry, then all his calculations will lose their meaning. The relativity of time can be experienced quite clearly in a dream. Sometimes it seems to a person that his dream lasts for hours, but in fact everything happens in a matter of seconds.

In 1905, Albert Einstein proposed that the laws of physics are universal. So he created the theory of relativity. The scientist spent ten years proving his assumptions, which became the basis for a new branch of physics and gave new ideas about space and time.

Attraction or gravity

Two objects attract each other with a certain force. It's called gravity. Isaac Newton discovered three laws of motion based on this assumption. However, he assumed that gravity is a property of an object.

Albert Einstein in his theory of relativity relied on the fact that the laws of physics are valid in all frames of reference. As a result, it was discovered that space and time are intertwined into a single system known as "space-time" or "continuum". The foundations of the theory of relativity were laid, including two postulates.

The first is the principle of relativity, which says that it is impossible to determine empirically whether an inertial system is at rest or moving. The second is the principle of the invariance of the speed of light. He proved that the speed of light in a vacuum is a constant. Events that occur at a certain moment for one observer may occur for other observers at another time. Einstein also realized that massive objects cause distortion in spacetime.

Experimental data

Although modern instruments cannot detect continuum distortions, they have been proven indirectly.

Light around a massive object, such as a black hole, bends, causing it to act like a lens. Astronomers commonly use this property to study stars and galaxies behind massive objects.

The Einstein Cross, a quasar in the constellation Pegasus, is a perfect example of gravitational lensing. The distance to it is about 8 billion light years. From Earth, a quasar is visible due to the fact that between it and our planet there is another galaxy that works like a lens.

Another example would be the orbit of Mercury. It changes over time due to the curvature of space-time around the Sun. Scientists have found that in a few billion years, the Earth and Mercury may collide.

Electromagnetic radiation from an object may be slightly delayed inside gravitational field. For example, the sound from a moving source changes depending on the distance from the receiver. If the source moves towards the observer, the amplitude of the sound waves decreases. As the distance increases, the amplitude increases. The same phenomenon occurs with waves of light at all frequencies. This is called redshift.

In 1959, Robert Pound and Glen Rebka conducted an experiment to prove the existence of redshift. They fired gamma rays of radioactive iron at the tower of Harvard University and found that the particle oscillation frequency at the receiver was less than expected due to distortion caused by gravity.

Collisions between two black holes are thought to create "ripples" in

It explained the regularity of the movement of two objects relative to each other in the same coordinate system under the condition of a constant speed and uniformity of the external environment.

The fundamental substantiation of SRT was based on two components:

1. Analytical data obtained empirically. When observing moving bodies in one structural parallel, the nature of their movement, significant differences, and features were determined;
2. Determination of speed parameters. The only unchangeable value was taken as a basis - the "speed of light", which is equal to 3 * 10^8 m / s.

The path of the formation of the Theory of Relativity

The emergence of the theory of relativity was made possible by scientific works Albert Einstein, who was able to explain and prove the difference in the perception of space and time depending on the position of the observer and the speed of movement of objects. How did it happen?

In the middle of the 18th century, a mysterious structure called aether became a key base for research. According to preliminary data and conclusions of the scientific group, this substance is able to penetrate through any layers without affecting their speed. It has also been suggested that changes in the external perception of speed change the speed of light itself ( modern science its constancy has been proven).

Albert Einstein, having studied these data, completely rejected the doctrine of the ether and dared to suggest that the speed of light is a determinant quantity that does not depend on external factors. According to him, only the visual perception changes, but not the essence of the ongoing processes. Later, to prove his beliefs, Einstein conducted a differentiated experiment that proved the validity of this approach.

The main feature of the study was the introduction of the human factor. Several persons were asked to move from point A to point B in parallel, but at different speeds. Upon reaching the starting point, these people were asked to describe what they saw around and their impression of the process. Each person from the selected group made their own conclusions and the result did not match. After the same experience was repeated, but people moved at the same speed and in the same direction, the opinion of the participants in the experiment became similar. Thus, the final result was summed up and Einstein's theory has found for certain confirmation.

The second stage in the development of SRT is the doctrine of the space-time continuum

The basis of the doctrine of the space-time continuum was the connecting thread between the direction of movement of an object, its speed and mass. Such a "hook" for further research was provided by the first successful demonstrative experiment conducted with the participation of outside observers.

The material universe exists in three phases of measuring direction: right-left, up-down, forward-backward. If you add to them a constant measure of time (the previously mentioned "speed of light"), you get a definition of the space-time continuum.

What role does the mass fraction of the measurement object play in this process? All schoolchildren and students are familiar with the physical formula E \u003d m * c², in which: E is energy, m is body mass, c is speed. According to the law of application of this formula, the mass of the body increases significantly due to the increase in the speed of light. It follows from this that the higher the speed, the greater will be the mass of the original object in any of the directions of motion. And the space-time continuum only dictates the order of increase and expansion, the volume of space (when we are talking about elementary particles on which all physical bodies are built).

Proof of this approach was the prototypes with which scientists tried to reach the speed of light. They clearly saw that with an artificial increase in body weight, it becomes increasingly difficult to achieve the desired acceleration. This required a constant inexhaustible source of energy, which simply does not exist in nature. After receiving the conclusion Albert Einstein's theory has been fully proven.

The study of relativity requires a significant understanding of the physical processes and fundamentals mathematical analysis that take place in high school and in the first years of vocational technical schools, higher educational institutions technical profile. Without introducing the basics to master full information and it is simply not possible to assess the importance of the research of a brilliant physicist.

The theory of relativity was proposed by the brilliant scientist Albert Einstein in 1905.

The scientist then spoke about a particular case of his development.

Today it is commonly called the Special Theory of Relativity or SRT. SRT studies physical principles uniform and straight motion.

In particular, this is how light moves, if there are no obstacles in its path, much is devoted to it in this theory.

Einstein laid down two fundamental principles at the basis of SRT:

1. The principle of relativity. Any physical laws are the same for stationary objects and for bodies moving uniformly and rectilinearly.
2. The speed of light in vacuum is the same for all observers and is equal to 300,000 km/s.

The theory of relativity is verifiable in practice, Einstein presented evidence in the form of experimental results.

Let's look at the principles with examples.

• Imagine that two objects are moving at constant speeds in a straight line. Instead of considering their movements relative to a fixed point, Einstein proposed to study them relative to each other. For example, two trains travel on adjacent tracks at different speeds. You are sitting in one, in the other, on the contrary, is your friend. You see it, and its speed relative to your view will depend only on the difference in the speeds of the trains, but not on how fast they go. At least until the trains start speeding up or turning.
• They like to explain the theory of relativity using space examples. This is because the effects increase with increasing speed and distance, especially considering that light does not change its speed. In addition, in a vacuum, nothing prevents the propagation of light. So, the second principle proclaims the constancy of the speed of light. If you strengthen and turn on the radiation source on spaceship, then whatever happens to the ship itself: it can move at high speed, hang motionless or disappear altogether together with the emitter, the observer from the station will see the light after a period of time that is the same for all incidents.

General theory of relativity.

From 1907 to 1916 Einstein created general theory relativity. In this section of physics, the movement of material bodies in general is studied, objects can accelerate and change trajectories. The general theory of relativity combines the doctrine of space and time with the theory of gravity, establishes relationships between them. Another name is also known: the geometric theory of gravity. The general theory of relativity is based on the conclusions of the special one. Mathematical calculations in this case are extremely complex.

Let's try to explain without formulas.

Postulates of the General Theory of Relativity:

• the environment in which objects and their movement are considered is four-dimensional;
• All bodies fall at a constant speed.

Let's move on to the details.

So, in general relativity, Einstein uses four dimensions: he supplemented the usual three-dimensional space with time. Scientists call the resulting structure the space-time continuum or space-time. It is argued that four-dimensional objects are unchanged when moving, but we are able to perceive only them 3D projections. That is, no matter how you bend the ruler, you will see only projections of an unknown 4-dimensional body. Einstein considered the space-time continuum to be indivisible.

Concerning gravity, Einstein put forward the following postulate: gravity is a curvature of space-time.

That is, according to Einstein, the fall of an apple on the inventor's head is not a consequence of attraction, but a consequence of the presence of mass-energy at the affected point in space-time. On a flat example: let's take a canvas, stretch it on four supports, place a body on it, we see a dent in the canvas; lighter bodies that are near the first object will roll (not be attracted) as a result of the canvas curvature.

So it is proved that the rays of light are bent in the presence of gravitating bodies. Also experimentally confirmed time dilation with increasing altitude. Einstein concluded that space-time is curved in the presence of a massive body and gravitational acceleration is only a projection into 3D of uniform motion in 4-dimensional space. And the trajectory of small bodies rolling down on the canvas towards a larger object remains straight for them.

Currently, general relativity is the leader among other theories of gravity and is used in practice by engineers, astronomers and developers of satellite navigation. Albert Einstein is actually a great reformer of science and the concept of natural science. In addition to the theory of relativity, he created the theory brownian motion, explored the quantum theory of light, participated in the development of the foundations of quantum statistics.

The use of site materials is allowed only if an active link to the source is placed.