In this short article I will give just about the distribution of matter in the universe at different scales and some of the basics of modern cosmology.

Let me start with the most interesting small cosmological point of view – the size of the solar system. This size is about 50 AU (Astronomical Units) ? 7.5 billion kilometers decide (km), if we consider the limits of the solar system, define the orbit of Pluto. The gravitational field of the sun dominates the area in the immediate vicinity of the scale sparkles of ? 2 × 10 ^ 13 km = 20 trillion kilometers. This scale can also be seen as the size of the solar system in a sense, although the average density of matter (gas, dust, etc.) is extremely low, about 100 billion kilometers away from the sun.

The main source of visible light in the universe is the nuclear fusion in stars (mostly hydrogen and helium). Our sun is a typical yellow dwarf star with a mass of about 10 ^ 30 kg – 100 times more mass than all the planets of the solar system together. We can say that we live in the same gravitational field of a star is rather low, as there are stars in our galaxy 100 times as massive as the sun. Considering that the nearest star, the extent of the box that contains it is in the order of 1 light-year length of the path through a light beam is used for a year. For example, the nearest star, Proxima Centauri, 3261 years of light ? 1 parsec (pc) away from us. The name of unity “parsec” is that Proxima Centauri has a parallax of about one arc second. Considering that, the speed of light 300000 km / s is checked, we, if one light year ? 10 ^ 13 km, while a parsec is ? 3 × 10 ^ 13 km.

The size of the box with the nearby stars is about 1 parsec. If we increase the size of the box after 1000, we find that star clusters, interstellar gas, called dark matter in gravitationally bound conglomerates of matter galaxies combined. The solar system is located away from the center of our galaxy is called the Orion spiral arm. The name is because the stars of the constellation Orion, as the red giant Betelgeuse – belong to the same arm – the brightest star in the sky ninth.

The typical number of stars in a galaxy is extremely important. For instance, contains our own galaxy (Milky Way) 100 billion euros (billion) stars. He has a disk shape with a radius of 12,500 parsecs, and a width of only about 300 parsecs. This disk rotates extremely thin differential with the full period of about 200 million years – as the dinosaurs were eliminated from the surface of the earth during the past year, Galactic. Big old galaxies (including Milky Way) usually have a spiral shape. The reason for this is that the rotating disk of dust particles in gravitational interaction is unstable, and the gravitational instability breaks the glass in a spiral structure. The characteristic length scale of the box with our galaxy, but not the other galaxy is 10,000 light years.

Now let us turn again to increase the size of the box, this time 10 times. We will see that the Milky Way in a small group of galaxies concentrated (LGG) is. All nearby galaxies in this field are much smaller than the Milky Way’s gravitational field is well located (in other words, they are satellites of the Milky Way in the same direction as the Moon is the satellite of the Earth). The nearest galaxy, the Milky Way is the Large Magellanic Cloud (50 kiloparsecs or 50,000 parsecs ? 1.5 × 10 ^ 18 km). The galaxy closest to the size of our own (actually slightly larger) 770 000 parsecs and is called the Andromeda galaxy. A local group of galaxies typically has a volume of several cubic megaparsecs or millions of parsecs. Megaparsec is the preferred unit is a cosmologist, an MPC ? 10 ^ 22 m. These groups of galaxies in galaxy clusters in turn (some of these clusters contain more than 10 000 galaxies) activities. Our local group is in the gravity field and the Virgo cluster itself.

Let us once again to increase the size of the box 10 times. Not surprisingly, it seems that galaxy clusters are grouped into superclusters, but it is surprising that they are the largest collapsed gravitationally objects in nature – in other words, there’s no such thing as super super clusters of galaxies in the universe. The structure of superclusters and their interaction with the gravity felt on a scale of several hundred million light years, or hundreds of megaparsec. In particular, the superclusters of galaxies, the filaments and walls associated with a foam-like structure of matter and gravitational potential called the cosmic web to create. Empty in this web are as large as 50 by megaparsec.

Understanding the structure of the cosmic web is defined by the gravitational instability, and it takes time to develop, on can conclude that the superclusters are collapsed most of the objects, that age was the universe, and also his first state was very symmetrical. In fact, we again have to increase by 10 times the scale of the box. What we find is the map of the universe (about 2 million nearby galaxies) with a characteristic scale of about 3000 megaparsec. This is consistent with the size of the observable patch of the universe – that is, we are not able to probe the physics beyond this scale, even with the best astronomical instruments that we currently have (such as Hubble Space Telescope). In this patch the size of a gigaparsec, the universe is extremely smooth, homogeneous and isotropic. In some ways, the qualitative discussion of the evolution of the universe is possible at any time and cosmology can be considered a legitimate daughter of astronomy. Of course, variations in the density of matter in the universe is homogeneous (we live in such a fluctuation), but their relative amplitude is about 10 ~ 10 ^ -5 ^ -4 on scales of about 1 gigapersec.

Although cosmologists are no data on the distribution of matter and the gravitational potential at a scale larger than 1 gigaparsec have shown the theory that the qualitative picture above, only the extent of changes 13 billion light years (the cosmological horizon scale), although the relative amplitude of the fluctuations begins to increase slightly, while the scale is getting bigger. Standard inflationary paradigm forward, and the relative amplitude increases further the fluctuations of the gravitational potential until it is on the order called by one on the scale of eternal inflation LvEI ~ 13 billion light-years × e ^ N where N is the number more than 60 years and depends on the model of inflation in particular. While the universe is homogeneous and isotropic on scales below, he again ceases to be homogeneous and isotropic L> L ^ AU. In addition, there may be a fractal in a sense – the structure of the gravitational potential to be huge against these benchmarks seem self-replicating.

Think in terms of the propagation of light, and reminded that the speed of light with the highest possible speed in nature, it is evident that the distance or length scale of the general relativity theory – the theory that govern the physical astronomical standards – is quite the same as the time scale. Meet in other words, greater distances to earlier stages of evolution of our universe, as more time passed for the light from distant objects to us. Observing the Universe, we see a film, his first shot corresponding to very distant objects in the sky and the last one – in physics at the scale of the magnitude of the solar system.