The question put in the title of this section, for modern astrophysics is not idle character. Faced in everyday life with the stars, each man for himself creates his individual perception of space. The most part of the history of mankind, the only source of knowledge (and views) about space was a normal human eye.

The contemplation of the painting starry sky suppressed and continues to suppress a person's self-aware grain of sand in a giant ocean of matter. With the help of view, we can fix in the sky just a few thousand stars. However, this relatively small amount is quite enough to understand how grandiose spatial and temporal boundaries of the process playing out before us.

Now, at the end of the twentieth century, few astronomers uses visual observation of a starry sky. Replaced the simplest telescopes came optical system type Large 6-meter telescope of the Special astrophysical Observatory of the Russian Academy of Sciences (www. sao. ru);

the network of the largest telescopes in Chile and Australia, the famous 5,8-meter telescope at mount Palomar and a number of others.

These telescopes registration of the images is not conceivable without the use of special systems amplify the signal and its computer processing, pushing the boundaries of penetration into the depths of space by several billion light years.

However, the capabilities of ground-based telescopes are very close to the limit of sensitivity due fatal interference associated with non-stationarity of the earth's atmosphere. That is why the starting and the successful functioning of the orbiting Hubble space telescope marks a new phase in astronomy, work-related space systems, free from atmospheric interference.

It's about this stage in the development of cosmonautics said I.S. Shklovsky in his book the universe, life, mind another ten years before the practical realization of the satellite astronomy.

As illustrate the possibilities of space research space, we present a picture of the world of galaxies, made space telescope Hubble.

This picture shows how have concentrated the entire history of the formation of structures in the Universe, starting with the dwarf galaxies up to galaxies, very similar to ours. Astrophysicists have long predicted that the formation of structures in the Universe should be achieved by skachivaniya low-mass objects (dwarf galaxies) in the complexes greater and greater masses.

Dwarf galaxies, who lived in the Universe is about 10 billion years ago were the original building blocks from which formed the larger galaxy. But the light from these objects, emitted 10 billion years ago, and today carries information about the condition of substance, except when the first galaxies other structures in the Universe!

Based on the data of deep reviews of galaxies can be identified and the average density of matter in the Universe. Today, these estimates indicate that the average space is extremely sparse. If the unit of measurement density to select the density of plain water (1 gram per cubic centimeter) for comparison, the average density of matter in galaxies such as our might have put it in a fraction, the numerator of which would be standing unit, and the denominator of the number represented by the unit with 24 zeros! And for the average density of matter in the Universe in the denominator would add Yeshe six zeros! This shows how rarefied the average is our universe.

What is the reason for the emptiness of space? The answer to this question in 1929 gave an outstanding astronomer Edwin Hubble:

The universe is sparse because it expands!