General theory of relativity(GR) is a geometric theory of gravity published by Albert Einstein in 1915-1916. Within this theory, which is further development special theory of relativity, it is postulated that gravitational effects are caused not by the force interaction of bodies and fields located in space-time, but by the deformation of space-time itself, which is associated, in particular, with the presence of mass-energy. Thus, in general relativity, as in other metric theories, gravity is not a force interaction. General relativity differs from other metric theories of gravity by using Einstein's equations to relate the curvature of spacetime to the matter present in space.

OTO is currently the most successful gravitational theory well confirmed by observations. The first success of general relativity was to explain the anomalous precession of Mercury's perihelion. Then, in 1919, Arthur Eddington reported the observation of a deflection of light near the Sun during a total eclipse, which confirmed the predictions of general relativity.

Since then, many other observations and experiments have confirmed a significant number of the theory's predictions, including gravitational slowdown time, gravitational redshift, signal delay in the gravitational field and, so far only indirectly, gravitational radiation. In addition, numerous observations are interpreted as confirmation of one of the most mysterious and exotic predictions of the general theory of relativity - the existence of black holes.

Despite the overwhelming success of general relativity, there is discomfort in the scientific community that it cannot be reformulated as the classical limit of quantum theory due to the appearance of irremovable mathematical divergences when considering black holes and space-time singularities in general. A number of alternative theories have been proposed to address this problem. Current experimental evidence indicates that any type of deviation from general relativity should be very small, if it exists at all.

Basic principles of general relativity

Newton's theory of gravity is based on the concept of gravity, which is a long-range force: it acts instantly at any distance. This instantaneous nature of the action is incompatible with the field paradigm of modern physics and, in particular, with the special theory of relativity created in 1905 by Einstein, inspired by the work of Poincaré and Lorentz. In Einstein's theory, no information can spread faster speed light in a vacuum.

Mathematically, Newton's gravitational force is derived from the potential energy of a body in a gravitational field. The gravitational potential corresponding to this potential energy obeys the Poisson equation, which is not invariant under Lorentz transformations. The reason for the non-invariance is that the energy in the special theory of relativity is not a scalar quantity, but goes into the time component of the 4-vector. The vector theory of gravity turns out to be similar to Maxwell's theory of the electromagnetic field and leads to negative energy of gravitational waves, which is associated with the nature of the interaction: like charges (masses) in gravity attract, and not repel, as in electromagnetism. Thus, Newton's theory of gravity is incompatible with the fundamental principle of the special theory of relativity - the invariance of the laws of nature in any inertial frame of reference, and the direct vector generalization of Newton's theory, first proposed by Poincaré in 1905 in his work "On the Dynamics of the Electron", leads to physically unsatisfactory results. .

Einstein began searching for a theory of gravity that would be compatible with the principle of the invariance of the laws of nature with respect to any frame of reference. The result of this search was the general theory of relativity, based on the principle of identity of gravitational and inertial mass.

The principle of equality of gravitational and inertial masses

In classical Newtonian mechanics, there are two concepts of mass: the first refers to Newton's second law, and the second to the law gravity. The first mass - inertial (or inertial) - is the ratio of the non-gravitational force acting on the body to its acceleration. The second mass - gravitational (or, as it is sometimes called, heavy) - determines the force of attraction of the body by other bodies and its own force of attraction. Generally speaking, these two masses are measured, as can be seen from the description, in different experiments, so they do not have to be proportional to each other at all. Their strict proportionality allows us to speak of a single body mass in both non-gravitational and gravitational interactions. By a suitable choice of units, these masses can be made equal to each other. The principle itself was put forward by Isaac Newton, and the equality of masses was verified by him experimentally with a relative accuracy of 10?3. At the end of the 19th century, Eötvös conducted more subtle experiments, bringing the accuracy of the verification of the principle to 10?9. During the 20th century, experimental techniques made it possible to confirm the equality of the masses with a relative accuracy of 10x12-10x13 (Braginsky, Dicke, etc.). Sometimes the principle of equality of gravitational and inertial masses is called the weak principle of equivalence. Albert Einstein put it at the basis of the general theory of relativity.

The principle of movement along geodesic lines

If the gravitational mass is exactly equal to the inertial mass, then in the expression for the acceleration of the body, which is affected only gravitational forces, both masses are reduced. Therefore, the acceleration of the body, and consequently, its trajectory does not depend on the mass and internal structure body. If all bodies at the same point in space receive the same acceleration, then this acceleration can be associated not with the properties of the bodies, but with the properties of the space itself at this point.

Thus, the description of the gravitational interaction between bodies can be reduced to a description of the space-time in which the bodies move. It is natural to assume, as Einstein did, that bodies move by inertia, that is, in such a way that their acceleration in their own reference frame is zero. The trajectories of the bodies will then be geodesic lines, the theory of which was developed by mathematicians back in the 19th century.

The geodesic lines themselves can be found by specifying in space-time an analogue of the distance between two events, traditionally called an interval or a world function. The interval in three-dimensional space and one-dimensional time (in other words, in four-dimensional space-time) is given by 10 independent components of the metric tensor. These 10 numbers form the space metric. It defines the "distance" between two infinitely close points of space-time in different directions. The geodesic lines corresponding to the world lines of physical bodies whose speed is less than the speed of light turn out to be the lines of the greatest proper time, that is, the time measured by a clock rigidly fastened to the body following this trajectory. Modern experiments confirm the motion of bodies along geodesic lines with the same accuracy as the equality of gravitational and inertial masses.

Curvature of space-time

If two bodies are launched from two close points parallel to each other, then in the gravitational field they will gradually either approach or move away from each other. This effect is called the deviation of geodesic lines. A similar effect can be observed directly if two balls are launched parallel to each other over a rubber membrane, on which a massive object is placed in the center. The balls will disperse: the one that was closer to the object pushing through the membrane will tend to the center more strongly than the more distant ball. This discrepancy (deviation) is due to the curvature of the membrane. Similarly, in space-time, the deviation of geodesics (the divergence of the trajectories of bodies) is associated with its curvature. The curvature of space-time is uniquely determined by its metric - the metric tensor. The difference between the general theory of relativity and alternative theories of gravity is determined in most cases precisely in the way of connection between matter (bodies and fields of a non-gravitational nature that create a gravitational field) and the metric properties of space-time.

Space-time GR and the strong equivalence principle

It is often incorrectly considered that the basis of the general theory of relativity is the principle of equivalence of the gravitational and inertial fields, which can be formulated as follows:
Relatively small local physical system, located in a gravitational field, is indistinguishable in behavior from the same system located in an accelerated (relative to the inertial reference frame) reference frame, immersed in the flat space-time of special relativity.

Sometimes the same principle is postulated as "local validity of special relativity" or called the "strong equivalence principle".

Historically, this principle really played a big role in the development of the general theory of relativity and was used by Einstein in its development. However, in the most final form of the theory, it is not actually contained, since space-time in both accelerated and original system reference in the special theory of relativity is not curved - flat, and in the general theory of relativity it is curved by any body and it is its curvature that causes the gravitational attraction of bodies.

It is important to note that the main difference between the space-time of the general theory of relativity and the space-time of the special theory of relativity is its curvature, which is expressed by a tensor quantity - the curvature tensor. In the space-time of special relativity, this tensor is identically equal to zero and the space-time is flat.

For this reason, the name "general relativity" is not entirely correct. This theory is only one of a number of theories of gravity currently being considered by physicists, while special theory relativity (more precisely, its principle of space-time metricity) is generally accepted scientific community and is Foundation stone basis of modern physics. It should, however, be noted that none of the other developed theories of gravity, except general relativity, has stood the test of time and experiment.

Main Consequences of General Relativity

According to the correspondence principle, in weak gravitational fields, the predictions of general relativity coincide with the results of applying Newton's law of universal gravitation with small corrections that increase as the field strength increases.

The first predicted and verified experimental consequences of general relativity were three classical effects, listed below in chronological order of their first verification:
1. Additional shift of the perihelion of Mercury's orbit compared to the predictions of Newtonian mechanics.
2. Deviation of a light beam in the gravitational field of the Sun.
3. Gravitational redshift, or time dilation in a gravitational field.

There are a number of other effects that can be experimentally verified. Among them, we can mention the deviation and delay (Shapiro effect) of electromagnetic waves in the gravitational field of the Sun and Jupiter, the Lense-Thirring effect (precession of a gyroscope near a rotating body), astrophysical evidence for the existence of black holes, evidence for the emission of gravitational waves close systems double stars and the expansion of the universe.

So far, reliable experimental evidence refuting general relativity has not been found. The deviations of the measured values ​​of the effects from those predicted by general relativity do not exceed 0.1% (for the above three classical phenomena). Despite this, due to various reasons At least 30 alternative theories of gravity have been developed by theorists, and some of them make it possible to obtain results arbitrarily close to general relativity for the corresponding values ​​of the parameters included in the theory.

SRT, TOE - under these abbreviations lies the term "theory of relativity", familiar to almost everyone. Everything can be explained in simple terms, even the statement 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 with 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 by spending a similar thought experiment, Albert Einstein came to the conclusion that if these two situations are indistinguishable from each other, it means that in fact the body under the influence of gravity does not accelerate, this is a uniform motion that is curved under the influence of a massive body (in this case planets). Thus, accelerated motion is only a projection of uniform motion into three-dimensional space.

illustrative example

Another good example on the topic "The 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, we can put it this way: GR is at the heart of many modern technologies, and thanks to Einstein, we can easily find a pizzeria and a library in an unfamiliar area.

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 of the spacecraft had not been 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 with relative movement, their projections can 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.

Such a 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 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 the motion is uniform in four-dimensional space-time, but in the presence of massive bodies (for example,) it is curved and the uniform motion is projected into our usual three-dimensional space in the form of accelerated 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 the general theory of 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 is formed with infinitely high density, and such, 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.

It was said about this theory that only three people in the world understand it, and when mathematicians tried to express in numbers what follows from it, the author himself - Albert Einstein - joked that now he had ceased to understand it.

Special and general relativity are inseparable parts of the doctrine on which modern scientific views on the structure of the world are built.

"Year of Miracles"

In 1905, Annalen der Physik (Annals of Physics), a leading German scientific publication, published one after another four articles by 26-year-old Albert Einstein, who worked as a 3rd class examiner - a petty clerk - of the Federal Office for Patenting Inventions in Bern. He had collaborated with the magazine before, but the publication of so many papers in one year was an extraordinary event. It became even more outstanding when the value of the ideas contained in each of them became clear.

In the first of the articles, thoughts were expressed about the quantum nature of light, and the processes of absorption and release of electromagnetic radiation were considered. On this basis, the photoelectric effect was first explained - the emission of electrons by matter, knocked out by photons of light, formulas were proposed for calculating the amount of energy released in this case. It is for the theoretical development of the photoelectric effect, which became the beginning of quantum mechanics, and not for the postulates of the theory of relativity, Einstein will be awarded the Nobel Prize in Physics in 1922.

In another article, the foundation was laid for applied areas of physical statistics based on the study of the Brownian motion of the smallest particles suspended in a liquid. Einstein proposed methods for searching for patterns of fluctuations - random and random deviations physical quantities from their most likely values.

And finally, in the articles “On the electrodynamics of moving bodies” and “Does the inertia of a body depend on the energy content in it?” contained the germs of what will be designated in the history of physics as Albert Einstein's theory of relativity, or rather its first part - SRT - the special theory of relativity.

Sources and predecessors

At the end of the 19th century, it seemed to many physicists that most of the global problems of the universe had been solved, the main discoveries had been made, and humanity would only have to use the accumulated knowledge for powerful acceleration technical progress. Only some theoretical inconsistencies spoiled the harmonic picture of the Universe filled with ether and living according to immutable Newtonian laws.

Harmony was spoiled by Maxwell's theoretical research. His equations, which described the interactions of electromagnetic fields, contradicted the generally accepted laws of classical mechanics. It concerned the measurement of the speed of light in dynamic systems reference, when Galileo's principle of relativity ceased to work - the mathematical model of the interaction of such systems when moving at light speed led to the disappearance of electromagnetic waves.

In addition, the ether, which was supposed to reconcile the simultaneous existence of particles and waves, macro and microcosm, did not yield to detection. The experiment, which was conducted in 1887 by Albert Michelson and Edward Morley, was aimed at detecting the “ethereal wind”, which inevitably had to be recorded by a unique device - an interferometer. The experiment lasted a whole year - the time of the complete revolution of the Earth around the Sun. The planet had to move against the ether flow for half a year, the ether had to “blow into the sails” of the Earth for half a year, but the result was zero: no displacement of light waves under the influence of the ether was found, which cast doubt on the very existence of the ether.

Lorentz and Poincaré

Physicists have tried to find an explanation for the results of experiments to detect the ether. Hendrik Lorentz (1853-1928) proposed his mathematical model. It brought back to life the ethereal filling of space, but only under a very conditional and artificial assumption that when moving through the ether, objects can contract in the direction of movement. This model was finalized by the great Henri Poincaré (1854-1912).

In the works of these two scientists, for the first time, concepts appeared that largely constituted the main postulates of the theory of relativity, and this does not allow Einstein's accusations of plagiarism to subside. These include the conditionality of the concept of simultaneity, the hypothesis of the constancy of the speed of light. Poincaré admitted that high speeds Newton's laws of mechanics need to be revised, he made a conclusion about the relativity of motion, but in application to the ethereal theory.

Special Relativity - SRT

Problems of correct description electromagnetic processes became an incentive for choosing a topic for theoretical developments, and Einstein's articles published in 1905 contained an interpretation of a particular case - uniform and rectilinear motion. By 1915, the general theory of relativity was formed, which explained the interactions and gravitational interactions, but the first was the theory, called the special one.

Einstein's special theory of relativity can be summarized in two basic postulates. The first extends the effect of Galileo's principle of relativity to everything physical phenomena and not just mechanical processes. In more general form it says: All physical laws are the same for all inertial (moving uniformly rectilinearly or at rest) frames of reference.

The second statement, which contains the special theory of relativity: the speed of propagation of light in vacuum for all inertial frames of reference is the same. Further, a more global conclusion is made: the speed of light is the maximum value of the transmission rate of interactions in nature.

In the mathematical calculations of SRT, the formula E=mc² is given, which has appeared in physical publications before, but it was thanks to Einstein that it became the most famous and popular in the history of science. The conclusion about the equivalence of mass and energy is the most revolutionary formula of the theory of relativity. The concept that any object with mass contains a huge amount of energy became the basis for developments in the use of nuclear energy and, above all, led to the appearance of the atomic bomb.

Effects of special relativity

Several consequences follow from SRT, which are called relativistic (relativity English - relativity) effects. Time dilation is one of the most striking. Its essence is that in a moving frame of reference time runs slower. Calculations show that on a spacecraft that made a hypothetical flight to the star system Alpha Centauri and back at a speed of 0.95 c (c is the speed of light), 7.3 years will pass, and on Earth - 12 years. Such examples are often given when explaining the theory of relativity for dummies, as well as the related twin paradox.

Another effect is a reduction in linear dimensions, that is, from the observer's point of view, objects moving relative to him at a speed close to c will have smaller linear dimensions in the direction of motion than their own length. This effect predicted by relativistic physics is called the Lorentz contraction.

According to the laws of relativistic kinematics, the mass of a moving object more mass rest. This effect becomes especially significant in the development of instruments for the study of elementary particles - it is difficult to imagine the operation of the LHC (Large Hadron Collider) without taking it into account.

space-time

One of critical components SRT is a graphical representation of relativistic kinematics, a special concept of a single space-time, which was proposed by the German mathematician Hermann Minkowski, who at one time was a teacher of mathematics to student Albert Einstein.

The essence of the Minkowski model lies in a completely new approach to determining the position of interacting objects. The special theory of relativity of time pays special attention. Time becomes not just the fourth coordinate of the classical three-dimensional coordinate system, time is not an absolute value, but an inseparable characteristic of space, which takes the form of a space-time continuum, graphically expressed as a cone, in which all interactions take place.

Such a space in the theory of relativity, with its development to a more general character, was later subjected to further curvature, which made such a model suitable for describing gravitational interactions as well.

Further development of the theory

SRT did not immediately find understanding among physicists, but gradually it became the main tool for describing the world, especially the world of elementary particles, which became the main subject of study of physical science. But the task of supplementing SRT with an explanation of the gravitational forces was very relevant, and Einstein did not stop working, honing the principles of the general theory of relativity - GR. The mathematical processing of these principles took quite a long time - about 11 years, and specialists from the fields of exact sciences adjacent to physics took part in it.

Thus, the leading mathematician of that time, David Hilbert (1862-1943), who became one of the co-authors of the equations of the gravitational field, made a huge contribution. They were the last stone in the construction of a beautiful building, which received the name - the general theory of relativity, or GR.

General relativity - GR

The modern theory of the gravitational field, the theory of the "space-time" structure, the geometry of "space-time", the law of physical interactions in non-inertial frames of reference - all these are the various names that Albert Einstein's general theory of relativity is endowed with.

The theory of universal gravitation, which for a long time determined the views of physical science on gravity, on the interactions of objects and fields of various sizes. Paradoxically, but its main drawback was the intangibility, illusory, mathematical nature of its essence. There was a void between stars and planets, an attraction between celestial bodies explained by the long-range action of certain forces, and instantaneous. Albert Einstein's general theory of relativity filled gravity with physical content, presented it as a direct contact of various material objects.

The geometry of gravity

The main idea with which Einstein explained gravitational interactions is very simple. He declares the physical expression of the forces of gravity to be space-time, endowed with quite tangible features - metrics and deformations, which are influenced by the mass of the object around which such curvatures are formed. At one time, Einstein was even credited with calls to return to the theory of the universe the concept of ether, as an elastic material medium that fills space. He also explained that it was difficult for him to call a substance that has many qualities that can be described as a vacuum.

So gravity is a manifestation geometric properties four-dimensional space-time, which was designated in SRT as uncurved, but in a more common cases This is endowed with a curvature that determines the movement of material objects, which are given the same acceleration in accordance with the principle of equivalence declared by Einstein.

This fundamental principle of the theory of relativity explains many of the "bottlenecks" of the Newtonian theory of universal gravitation: the curvature of light observed when it passes near massive space objects during some astronomical phenomena and, noted by the ancients, the same acceleration of the fall of bodies, regardless of their mass.

Modeling the curvature of space

A common example that explains the general theory of relativity for dummies is the representation of space-time in the form of a trampoline - an elastic thin membrane on which objects (most often balls) are laid out, imitating interacting objects. Heavy balls bend the membrane, forming a funnel around them. A smaller ball launched on the surface moves in full accordance with the laws of gravity, gradually rolling into the depressions formed by more massive objects.

But this example is rather arbitrary. The real space-time is multidimensional, its curvature also does not look so elementary, but the principle of the formation of gravitational interaction and the essence of the theory of relativity become clear. In any case, a hypothesis that would more logically and coherently explain the theory of gravity does not yet exist.

Proofs of Truth

GR quickly came to be seen as a powerful foundation on which to build modern physics. The theory of relativity from the very beginning struck with its harmony and harmony, and not only specialists, and soon after its appearance began to be confirmed by observations.

The closest point to the Sun - the perihelion - of Mercury's orbit is gradually shifting relative to the orbits of other planets in the solar system, which was discovered back in the middle of the 19th century. Such a movement - precession - did not find a reasonable explanation within the framework of Newton's theory of universal gravitation, but was calculated with accuracy on the basis of the general theory of relativity.

The solar eclipse that occurred in 1919 provided an opportunity for yet another proof of general relativity. Arthur Eddington, who jokingly called himself the second person out of three who understand the basics of the theory of relativity, confirmed the deviations predicted by Einstein during the passage of photons of light near the star: at the time of the eclipse, a shift in the apparent position of some stars became noticeable.

The experiment to detect clock slowdown or gravitational redshift was proposed by Einstein himself, among other proofs of general relativity. Only later long years managed to prepare the necessary experimental equipment and conduct this experiment. The gravitational frequency shift of the radiation from the transmitter and receiver, spaced apart in height, turned out to be within the limits predicted by general relativity, and Harvard physicists Robert Pound and Glen Rebka, who conducted this experiment, further only increased the accuracy of measurements, and the relativity theory formula again turned out to be correct.

In substantiation of the most significant research projects outer space Einstein's theory of relativity is a must. Briefly, we can say that it has become an engineering tool for specialists, in particular those involved in satellite navigation systems - GPS, GLONASS, etc. It is impossible to calculate the coordinates of an object with the required accuracy, even in a relatively small space, without taking into account the slowdowns of signals predicted by general relativity. Especially when it comes to objects spaced apart by space distances where the error in navigation can be huge.

Creator of the theory of relativity

Albert Einstein was still a young man when he published the foundations of the theory of relativity. Subsequently, its shortcomings and inconsistencies became clear to him. In particular, the main problem General relativity became the impossibility of its growing into quantum mechanics, since the description of gravitational interactions uses principles that are radically different from each other. In quantum mechanics, the interaction of objects in a single space-time is considered, and according to Einstein, this space itself forms gravity.

Writing the "formula of all things" - unified theory field, which would eliminate the contradictions between general relativity and quantum physics, was Einstein's goal for many years, he worked on this theory until the last hour, but did not achieve success. The problems of general relativity have become a stimulus for many theorists in the search for more perfect models of the world. This is how string theories, loop quantum gravity and many others appeared.

The personality of the author of general relativity left a mark in history comparable to the importance for science of the theory of relativity itself. She does not leave indifferent so far. Einstein himself wondered why so much attention was paid to him and his work by people who had nothing to do with physics. Thanks to his personal qualities, famous wit, active political position and even expressive appearance, Einstein became the most famous physicist on Earth, the hero of many books, films and computer games.

The end of his life is described dramatically by many: he was alone, considered himself responsible for the appearance of the most terrible weapon that became a threat to all life on the planet, his theory unified field remained an unrealistic dream, but the best result can be considered the words of Einstein, spoken shortly before his death, that he completed his task on Earth. It's hard to argue with this.