How the Universe is Organized?

How the Universe is Organized?

Black hole| Astrophysics| Gravity| Universe| Cosmology

The observed structure of the Universe (galaxies, stars, planets) was created first of all by gravity. To understand, how the Universe can be organized we first need to understand, how works the gravity, collecting the matter in Universe in different compact structures.

As it was mentioned, the Newton’s theory of Gravitation did not explain how the gravity works. It simply states, that the forces between massive bodies are defined by the 4-th Newton’s Law,

F(r)= Gm1m2/r2

But why this Law looks as it looks – Newton left this topic open. Consciously! He simply did not know how to approach it.






An attempt to explain the gravitation was made by Albert Einstein in the very beginning of 20-th century. His famous General Relativity Theory was published in 1915–16.


Gravitation in General Relativity Theory is a geometrical effect! Any mass causes some curvature of space – where other massive object are moving along shortest trajectories (see illustration).


At certain range this effect is mathematically absolutely identical to Newton gravitation theory. But near bigger masses where forces are too strong, the Newton’s theory cannot be applied.



Many theoreticians share the opinion, that if there are several models, explaining one and the same effect, the true one will be usually the one that is the most BEAUTIFUL. Einstein gravitation theory is mathematically extremely beautiful!


One of the most beautiful results obtained based on the GRT is the impossibility of the equilibrium state of the Universe! The result was obtained in 1922 by Russian mathematician Alexander Friedman (1888 – 1923), who applied Einstein’s equations of GRT to the Universe taken as a whole (endless space, filled with homogeneously distributed matter) and found out, that those equations in this case simply have NO stationary solution! The Universe can either constantly expand, or collapse, or fluctuate!


Einstein himself, when he first saw this result published in “Zeitschrift fur Physics”, simply could not believe in it! He was sure that the Universe as a whole must be stationary.


But already in 1929 the American astronomer Edwin Hubble (1889-1953) proved, that Friedman is right – the Universe is expanding!

Basically the observed result is:

At relatively close distances (inside our Galaxy or among neighboring galaxies) space objects are moving in different directions with different speeds. But if we take the really far away objects (~108 light years from us or more) – than observations definitely show:

The further from us is the object – the faster it moves away from us.

The main indication of this regular runaway of the far away objects is the redshift in their spectra. All lines in those spectra are arranged in the same order as in spectra of radiation from nearby stars, but they all are proportionally shifted towards bigger wavelengths. This is the consequence of Doppler effect, which occurs when the source of radiation is moving away from the receiver.


The observed effect may happen only in one case – if the Universe is expanding as a whole – like a stretched rubber plane. But if it is expanding now – does it mean that initially it was much more compact with much higher density of matter?

Yes, it does. Initially, at the very beginning of its history, the Universe had practically infinite density of matter and energy, which at some moment exploded and started expanding. This theory, proposed initially by Russian and American physicist George Gamov (1904–1968) in 1948, received the name of Big Bang theory.

According to this theory, the Universe started expanding approximately 13–15 billion years ago from extremely hot and dense state, which in modern physics is called quark-gluon plasma. Actually the whole Universe was one tremendously big elementary particle, filled with chaotically moving and interacting with each other quarks, leptons, gluons and photons.

With the expansion of the Universe, started from the Big Bang Explosion, the density and temperature of It was gradually decreasing, and first the quarks united in inseparable groups forming protons, neutrons and small stable groups of them (like alpha-particles), than protons and alpha-particles captured electrons, forming atoms, than the expanding electrically neutral gas of hydrogen and helium atoms under the influence of the forces of gravitation started aggregating in the re-contracting clouds, forming galaxies and starts, which were then again exploding, creating heavy nuclei and heavy chemical atoms, which then were aggregated by gravity into new stars and planets etc., etc.

The Big Bang theory is a very popular topic in scientific popular products on TV and in the Internet. One can find plenty of information about it just making a search in the Internet with the key-words ‘Big Bang’. But one aspect of it is important to mention here.

At the very first moment of the life of the Universe, when it was a hot ‘bouillon’ of quarks, gluons, photons and leptons, all the available sorts of them must have been presented in it in comparable shares. As the distribution of energy over degrees of freedom of molecules in gas has to be uniform due to chaotic character of their collisions, the production of various elementary particles in chaotic reactions of intensively interacting quarks and leptons in this extremely hot initial ‘bouillon’ had also to be more or less equiprobable.

Moreover, as the number of degrees of freedom of molecules define the energy, accumulated by certain amount of gas at certain temperature – the number of sorts of elementary particles, that could have been produced in reactions, defines the density of energy in this initial ‘bouillon’, The more sorts of particles can be produced (the more ‘degrees of

Freedom’ we have) – the more will be the density of energy, and it means – the higher will be the mass of the Universe.

If it were initially too high – the gravity would stop the expansion of the Universe at some early phase and turn it back into super-hot state. No planets, no life would ever have chance to emerge in such Universe.

If the density of the initial Universe was too small – the gravity would not be able to compete with initial expansion even at the phase when the atomic gas will be formed. It will fail to aggregate matter into stars and planets – and again there will be no chance for life to emerge in such a Universe.

The fact that we (living creatures) do exist thus is due to the fact that the energy density, provided by exactly three generations of elementary particles – quarks and leptons – allowed gravity to slow down the initial expansion of the Universe just in time, to be able to form stars and planets and thus the conditions for the life to emerge.

Everything had started from the tremendous energy blow up. Then the gravity (means the changing geometry of space and time) brought the Universe to the observed now shape and structure.

Who Created the Design of All This? – Let us leave this question open…