The question about the evolution of the universe has always been open to humanity. Starry sky over your head for a long time was the symbol of eternity and immutability. Only in the New time people realized that "fixed" stars actually moving with huge velocity. In XX century the humanity accustomed to the more bizarre fact: the distances between star systems - galaxies that are not related to each other by the forces of gravity, is constantly increasing. And it is not in the nature of galaxies the universe is constantly growing! Science had to part with one of its fundamental principles: all things can change in this world, but the world as a whole is always the same. This can be considered a major scientific event of the XX century

It all started when albert Einstein created the General theory of relativity. In its equations describes the fundamental properties of matter, space and time. ("Relative" in Latin sounds like rela-tivus, so the theory based on the theory of relativity, are called relativistic.)

Applying his theory to the Universe as a whole system, Einstein found that this decision, which would correspond not changing over time, the universe does not work. This result did not satisfy the great scientist. To achieve stationary solutions to their equations, Einstein introduced additional element - the so-called lambda member. However, until now no one has been able to find any physical substantiation of this additional term.

In the early 20's. the Soviet mathematician Alexander Alexandrovich Friedman decided to Universe equations of General relativity, without imposing conditions of stationarity. He proved that there may be two solutions to the Universe: the expanding and shrinking world peace. Received by the Friedman equations used to describe the evolution of the Universe and at the present time.

All these theoretical reasoning was not contacted by scientists with the real world, while in 1929, the American astronomer Edwin Hubble not confirmed the extension of the visible part of the Universe. He used the Doppler effect. The lines in the spectrum of a moving source is shifted by an amount proportional to the speed of zoom, so the speed of a galaxy can always be calculated on a repositioning of its spectral lines.

Even in the second decade of XX century American astronomer Just sly-fer, examining the spectra of several galaxies, noted that most of them spectral line is shifted to the red. This meant that they are removed from our Galaxy at speeds of hundreds of kilometers per second.

Hubble has determined the distance to a small number of galaxies and their speed. His observations indicated that the farther away the galaxy, the faster it removes from us. The law on which the removal rate is proportional to the distance, called the Hubble law.

Does this mean that our Galaxy is the center of which is the expansion? From the point of view of astronomers, this is impossible. The observer anywhere in the Universe should see the same picture: all the galaxies would have redshifts, proportional to their distance. The space itself is like blown. If on the air ball to draw galaxy and start to inflate it, then the distance between them will increase, and the faster, the further away they are from each other. The only difference is that drawn on the ball galaxies themselves are increased, the real star system everywhere in the Universe preserve their volume. This is because their constituent stars are connected among themselves by forces of gravity.

The fact of permanent expansion of the Universe is set firmly. The most distant known galaxies and kVA-Sarov have such a large red shift that the wavelengths of all the lines in their spectra are more than the close of sources, five to six times!

But if the universe is expanding, but today we see it not such what it was in the past. Billions of years ago galaxies were much closer to each other. Even before the individual galaxies simply could not exist, and even closer to the beginning of the extension could not be even stars. This epoch - the beginning of expansion of the Universe is removed from us at 12-15 billion years. Estimation of the age of galaxies is still too close to specify these figures. But reliably established that the oldest stars of different galaxies are about the same age. Consequently, most star systems emerged in the period when the density of matter in the Universe was much higher than today.

At the initial stage all the matter of the Universe was so high density, that it is impossible to imagine. The idea of expansion of the Universe from the super-dense state introduced in 1927, a Belgian astronomer Georges Lemaitre, and the assumption that the initial stuff was very hot, first expressed George Gamow in 1946 Later this hypothesis confirmed the discovery of the so-called background radiation. It remains an echo of the violent birth of the Universe often called the Big Bang. But still a lot of questions. That led to the formation of currently observable Universe, to the beginning of the Explosion? Why the space has three dimensions, and time is one? As a rapidly expanding Universe could appear stationary objects - stars and galaxies? What was before the Big Bang? Over the search for answers to these and many other questions are modern astronomers and physicists.