At the beginning of the 20th century was formulatedtheory of relativity. Every schoolboy knows what it is and who its creator is today. It is so fascinating that even people far from science are interested in it. In this article, the theory of relativity is described in an accessible language: what it is, what its postulates and applications are.
Говорят, что к Альберту Эйнштейну, ее создателю, epiphany came in a flash. The scientist allegedly rode a tram in Swiss Bern. He looked at the street clock and suddenly realized that this clock would stop if the tram accelerated to the speed of light. In this case, there would be no time. Time in the theory of relativity plays a very important role. One of the postulates formulated by Einstein - different observers perceive reality in different ways. This applies in particular to time and distance.
Accounting for the position of the observer
On that day, Albert understood that, in the languagescience, the description of any physical phenomenon or event depends on what the reference system is an observer. For example, if any passenger of the tram drops her glasses, they will fall vertically towards her. If you look from the position of a pedestrian standing on the street, then the trajectory of their fall will correspond to a parabola, as the tram moves and at the same time points fall. Thus, each has its own reference system. We propose to consider in more detail the basic tenets of the theory of relativity.
The law of distributed motion and the principle of relativity
Despite the fact that when changing the reference systemsdescriptions of events change, there are also universal things that remain unchanged. In order to understand this, you need to wonder not about falling points, but about the law of nature that causes this fall. For any observer, regardless of whether he is in a moving or fixed coordinate system, the answer to it remains unchanged. This law is called the law of distributed motion. It acts equally in the streetcar as well as on the street. In other words, if the description of events always depends on who observes them, then this does not apply to the laws of nature. They are, as is customary to be expressed in a scientific language, invariant. This is the principle of relativity.
Two theories of Einstein
This principle, like any other hypothesis,it was necessary to check first, correlating it with natural phenomena acting in our reality. Einstein derived 2 theories from the principle of relativity. Although they are related, they are considered separate.
Private, or special, theory of relativity(STR) is based on the position that for all possible reference systems, the speed of which is constant, the laws of nature remain the same. The general theory of relativity (GTR) extends this principle to any reference systems, including those that move with acceleration. In 1905, A. Einstein published the first theory. The second, more complex in terms of the mathematical apparatus, completed by 1916. The creation of the theory of relativity, both SRT and GR, became an important stage in the development of physics. Let us dwell on each of them.
Special theory of relativity
What is it, what is its essence?Let's answer this question. It is this theory that predicts many paradoxical effects that contradict our intuitive ideas about how the world works. We are talking about those effects that are observed when the speed of movement approaches the speed of light. The most famous among them is the effect of slowing down time (running hours). Clocks that move relative to the observer, go slower for him than those that are in his hands.
In the coordinate system when moving with speed,close to the speed of light, time is stretched relative to the observer, and the length of the objects (spatial extent), on the contrary, is compressed along the axis of the direction of this movement. Scientists call this effect the Lorentz-Fitzgerald contraction. Back in 1889, George Fitzgerald, an Italian physicist, described it. And in 1892, Hendrik Lorenz, a Dutchman, supplemented it. This effect explains the negative result, which gives the Michelson-Morley experience, in which the speed of movement of our planet in outer space is determined by the measurement of the "ether wind". These are the basic tenets of the theory of relativity (special). Einstein supplemented these equations with the formula for the mass transformation made by analogy. According to her, as the speed of the body approaches the speed of light, the mass of the body increases. For example, if the speed is 260 thousand km / s, that is, 87% of the speed of light, from the point of view of the observer who is in the resting frame, the mass of the object will double.
STO confirmations
Все эти положения, как бы они ни противоречили common sense, since the time of Einstein, has been directly and completely confirmed in many experiments. One of them was conducted by scientists at the University of Michigan. This curious experience confirms the theory of relativity in physics. The researchers placed aboard the airliner, which regularly made transatlantic flights, ultra-precise atomic clocks. Each time after his return to the airport, the readings of these watches were checked against the control. It turned out that the clock on the plane every time more and more lagged behind the control. Of course, it was only minor numbers, fractions of a second, but the fact itself is quite indicative.
Последние полвека исследователи изучают elementary particles on accelerators - huge hardware complexes. In them, beams of electrons or protons, that is, charged subatomic particles, are accelerated until their speeds approach the speed of light. After that, they are firing nuclear targets. In these experiments it is necessary to take into account the fact that the mass of particles increases, otherwise the results of the experiment cannot be interpreted. In this regard, SRT is no longer just a hypothetical theory. It has become one of the tools used in applied engineering, along with Newton's laws of mechanics. The principles of the theory of relativity have found great practical application today.
SRT and Newton's laws
By the way, speaking of Newton's laws (a portrait of thisthe scientist is presented above), it should be said that the special theory of relativity, which would seem to contradict them, actually reproduces the equations of Newton's laws almost exactly if used to describe bodies whose speed of movement is much less than the speed of light. In other words, if the special theory of relativity is applied, Newton's physics is not canceled at all. This theory, on the contrary, complements and expands it.
The speed of light is a universal constant.
Using the principle of relativity, one can understandWhy in this model of the structure of the world the speed of light plays a very important role, and not something else. This question is asked by those who are just starting their acquaintance with physics. The speed of light is a universal constant due to the fact that it is defined as such a natural science law (you can learn more about this by studying the Maxwell equations). The speed of light in a vacuum, due to the principle of relativity, is the same in any reference system. You might think that this is contrary to common sense. It turns out that the observer simultaneously receives light from both a stationary source and a moving one (no matter how fast it moves). However, it is not. The speed of light, due to its special role, is given a central place not only in the special, but also in GR. Let's tell about it.
General theory of relativity
It is used, as we said, for allreference systems, not necessarily those whose speed relative to each other is constant. Mathematically, this theory looks much more complicated than special. This explains the fact that 11 years have passed between their publications. The GR includes a special case as a special case. Consequently, the laws of Newton also enter into it. However, GRT goes much further than its predecessors. For example, it has a new way to explain gravity.
Fourth dimension
Благодаря ОТО мир становится четырехмерным:time is added to the three spatial dimensions. All of them are inseparable, therefore, it is necessary to speak not about the spatial distance existing in the three-dimensional world between two objects. We are now talking about space-time intervals between various events, uniting both their spatial and temporal distance from each other. In other words, time and space in the theory of relativity are considered as a kind of four-dimensional continuum. It can be defined as space-time. In this continuum, those observers who are moving relative to each other will even have different opinions about whether two events occurred at the same time, or whether one of them preceded the other. However, causal relationships are not violated. In other words, the existence of such a system of coordinates, where two events occur in different sequences and not simultaneously, does not allow even GTR.
GTR and the law of the world
According to the law of the world, openNewton, the force of mutual attraction exists in the universe between any two bodies. From this position, the Earth rotates around the Sun, since there are forces of mutual attraction between them. However, the GTR forces one to look at the phenomenon from the other side. Gravity, according to this theory, is a consequence of the "curvature" (deformation) of space-time, which is observed under the influence of mass. The heavier the body (in our example, the Sun), the more space-time bends under it. Accordingly, its gravitational field is stronger.
In order to better understand the essence of the theoryrelativity, we turn to the comparison. The Earth, according to GR, revolves around the Sun, like a small ball that rolls around a funnel cone created as a result of the space-time being "pushed through" by the Sun. And what we are accustomed to consider gravity, is actually an external manifestation of this curvature, and not force, in Newton's understanding. There is no better explanation of the phenomenon of gravity than that proposed in GR.
WG verification methods
We note that it is not easy to verify GR, since itsresults in laboratory conditions almost correspond to the law of the world. However, scientists still conducted a number of important experiments. Their results lead to the conclusion that Einstein's theory is confirmed. GTR, in addition, helps to explain the various phenomena observed in space. These are, for example, small deviations of Mercury from its stationary orbit. From the point of view of Newtonian classical mechanics, they cannot be explained. This is also why electromagnetic radiation emanating from distant stars is bent when it passes close to the Sun.
Результаты, предсказанные ОТО, на самом деле Significantly differ from those that give Newton's laws (his portrait is presented above) only when there are superstrong gravitational fields. Consequently, for a complete verification of general relativity, either very accurate measurements of objects of enormous mass or black holes are necessary, since our usual ideas are inapplicable to them. Therefore, the development of experimental methods of testing this theory is one of the main tasks of modern experimental physics.
The minds of many scientists, and people far from scienceoccupies the theory of relativity created by Einstein. What it is, we briefly told. This theory overturns our familiar ideas about the world, so interest in it still does not fade.
