Teoria Wielkiego Wybuchu i etapy rozwoju Wszechświata

Before you start, do the following.

• Recall Hubble's law regarding the escape of galaxies.

One of the most widespread theories describing the origin and developmentdevelopmentdevelopment of our Universe is the Big BangBig BangBig Bang theory. According to it, the origin of the Universe took place at one point with infinite density and temperature. This is the point where the laws of physics known to us did not function, as well as the notions of time and space.

At first it was assumed that the Universe is static, but Hubble observed that all distant galaxies are moving away from us and that the faster they are further away.

The Big Bang theory describes the evolution of the universe from its beginning to the present, assuming it is expanding all the time.

In the evolution of the Universe, the following cosmological epochs are distinguished.

Planck epochepochepoch (duration: 0 to 10Indeks górny -43^-43 s)

The first phase of the developmentdevelopmentdevelopment of the early Universe is called Planck epoch. It covered the time from 0 to 10Indeks górny -43^-43 s. It is assumed that very high temperatures of the order of 10Indeks górny 32³² K prevailed. We cannot yet describe what this state was or what processes occurred in it.

Hadronic epoch (duration: 10Indeks górny -43^-43 to 10Indeks górny -32^-32 s)

The period between 10Indeks górny -43^-43 s and 10Indeks górny -32^-32 s is the time in which the size of the Universe has increased 10Indeks górny 20²⁰ - 10Indeks górny 26²⁶ times - this period is called the inflationary epochepochepoch. At the end of this stage, the Universe's space consisted of a hot and dense mixture of quarks, antiquarks and gluons as well as photons, electrons and positrons. The prevailing temperature is slightly lower - of the order of 10Indeks górny 27²⁷ to 10Indeks górny 28²⁸ K.

Lepton epoch (duration: 10Indeks górny -4^-4 to 10 s)

The next stage was the merging of quarks into protons and neutrons, and when the Universe existed one second, and its temperature dropped to 5 billion Kelvin, there were processes of annihilation of electrons and positrons (after contact of electron and positron both particles disappear, and instead two photons of gamma radiation appear), as a result of which the number of photons increased.

Radiation epoch (duration: 10 s to approx. 100 million years)

The era of nucleosynthesis began - atomic nuclei of deuterium, tritium, and helium were created. It lasted about 4 minutes and it was at that time that the composition of the Universe was established (about 75% of protons and 24% of helium nuclei). Then the heavy nuclei could no longer be formed, because the temperature became too low for the helium nuclei to undergo fusion reactions and form heavier nuclei.

The further expansion of the Universe led to a decrease of temperature - protons and helium nuclei could be combined with electrons into neutral hydrogen and helium atoms. Radiation was then created which at the moment we observe as a relic radiation - cosmic microwave background radiation.

Galactic epoch (duration: 100 million years - up to now / probably 13,7 billion years)

The era of the formation of stars took place (about 100 million years), which then began to merge into galaxies (about 500 million years). The Sun and the Solar System were created around 4,6 billion years ago.

The average temperature in space is T = 2,725 K.

Remember

• The Big BangBig BangBig Bang theory describes a possible scenario of the creation of the Universe.

• The astronomical observations confirm the expansion of the Universe and allow determining its age.

• The current state of knowledge, however, does not allow us to find an unambiguous answer to what the absolute beginning of the Universe looked like.

Exercises

Glossary

Keywords

Big BangBig BangBig Bang

epochepochepoch

hadronshadronshadrons

inflationinflationinflation

leptonsleptonsleptons