Expansion of the Universe proceeds with delay, for the future there are two opportunities. Delay is proportional to substance density in the Universe. With expansion density falls, delay decreases. The situation when at today's speed of expansion density of substance is rather small also delay a little is possible. Then expansion will proceed is not limited.
It is interesting to compare the found t time which passed since the beginning of expansion, with age other objects in the Universe. For example, the age, so-called spherical congestions in a galaxy is estimated at 10-14 billion years.
Cepheids were open in other galaxies. Distance to these cepheids, so, and to galaxies in which they are, were much bigger, than the size of our own Galaxy. Thereby it was finalized that galaxies are far star systems similar sew.
Let's consider at first the gravity created on a surface of this sphere only by substance of the sphere and we will not consider all other substance of the Universe so far. Let the radius of a sphere be chosen not too big so the inclination field created by substance of a sphere Newton's theory for calculation of gravity is rather weak and is applicable. Then the galaxies which are on the boundary sphere it will be attracted to the center of a sphere with a force proportional to the mass of a sphere of M and inversely proportional to a square of its radius of R.
The idea of evolution of all Universe is represented quite natural and even necessary today. However so was not always. As well as any great scientific idea, it passed a difficult way of fight and formation, did not triumph in science yet. Today evolution of the Universe is the scientific fact which is comprehensively proved by numerous astrophysical supervision and having under themselves strong theoretical basis of all physics.
So, any two galaxies which are in the uniform Universe at R distance experience relative acceleration (negatively and, given by a formula It and means that the Universe has to be non-stationary. Really, if we presented that in some timepoint of a galaxy are based, do not move and density of substance in the Universe does not change, at the next moment of a galaxy would receive speeds under the influence of mutual inclination of all substance as there is an inclination acceleration given by a formula
This equation shows that acceleration and in direct ratio to distance. So, at the moment time and the speed of removal of galaxies and acceleration (delays are proportional to distance. But if it is proportional to distance and the speed and its change, so in the timepoints following the present proportionality of speed to distance will also remain. Thus, in Friedman's model always speeds of a razbeganiye of galaxies are proportional to distance, only the coefficient of proportionality changes eventually. Expansion is slowed down, and earlier this coefficient was more. In a similar way the distance between any two far galaxies in the Universe changes. Only according to that, more than this distance today, than R sphere radius, or is less, the schedule has to be in this way increased or reduced. Such schedules are represented in drawing
First, we will note the following important feature of the acceleration described above. Let's express the mass of a sphere of M through substance density ρ and the volume of a sphere 4/3 πR3, and we will substitute in a formula for acceleration. As a result we will receive
Now we will address to consideration of gravity in the Universe. In the previous point it was found out that in big scales distribution of substance in the Universe can be considered uniform. Everywhere only big scales therefore the substance is considered uniform are considered.
This formula is fair for v speeds, it is a lot of smaller velocity of light with when it is applicable the mechanic Newton. At the speeds close to light, the formula becomes complicated, but we now on it will not stop because we will consider speeds, small in comparison about the light.
Scientific physical cosmology can be considered as a child of the XX century. Only last century Albert Einstein created the relativistic theory of inclination (the general theory of relativity) which is the theoretical base of science about the Universe structure.