The Big Bang nucleosynthesis:
One may get a fair idea on how the Universe came into being from nothing from the Big Bang nucleosynthesis of the Universe. The nuclear reactions in a process called Big Bang nucleosynthesis. Nucleosynthesis is the formation of new atomic nuclei, the centres of atoms that are made up of protons and neutrons. The first nuclei were formed a few minutes after the Big Bang, a quark-gluon plasma, a soup of particles known as quarks and gluons, condensed into protons and neutrons, further process formed new atomic nuclei from pre-existing nucleons i.e. protons and neutrons, and nuclei.
Similarity:
Evidence of nucleosynthesis in other stars has been discovered in S-Type stars by Merrill (1952). Nucleosynthesis in main sequence stars involves fusion of 4 Hydrogen nuclei into Helium (He4 or α-particle) through a chain of reactions called the Proton-Proton chain (as first discovered by Hans Bethe in 1939). Stellar nucleosynthesis is the nuclear process by which new nuclei are produced. It occurs in stars during stellar evolution. It is responsible for the galactic abundances of elements from carbon to iron. The synthesis of the naturally occurring elements and their isotopes present in the Solar System solids may be divided into three broad segments: primordial nucleosynthesis (H, He), energetic particle (cosmic ray) interactions (Li, Be, B), and stellar nucleosynthesis (C and heavier elements).
The timeline of the early universe:
The timeline of the early universe outlines the formation and subsequent evolution of the Universe from the Big Bang (13.799 ± 0.021 billion years ago) to the present day. An epoch is a moment in time from which nature or situations change to such a degree that it marks the beginning of a new era or age.
The chronology of the universe:
The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. The earliest stages of the universe's existence are estimated as taking place 13.8 billion years ago, with an uncertainty of around 21 million years at the 68% confidence level.
The first 20 minutes:
- Planck epoch - the Planck epoch or Planck era is the earliest stage of the Big Bang, before the time passed was equal to the Planck time, tP, or approximately 10^−43 seconds. It is generally assumed that quantum effects of gravity dominate physical interactions at this time scale.
- Grand unification epoch - The Grand Unification Epoch took place from 10^-43 seconds to 10^-36 seconds after our universe was born. During this period, three of the four fundamental interactions—electromagnetism, the strong interaction, and the weak interaction—were unified as the electronuclear force. Gravity had separated from the electronuclear force at the end of the Planck era. The strong force separated from the other fundamental forces.
- Electroweak epoch - The quark epoch ended when the universe was about 10^−6 seconds old. The electroweak interaction is a fundamental force representing unification of the electromagnetic and weak nuclear interactions. The work of three physicists, Glashow, Weinberg, and Salam, showed that the electromagnetic and weak nuclear forces can be understood as a single interaction.
- Quark epoch - The quark epoch ended when the universe was about 10^−6 seconds old, when the average energy of particle interactions had fallen below the binding energy of hadrons. During the quark epoch the universe was filled with dense, hot quark–gluon plasma, containing quarks, leptons and their antiparticles.
- Hadron epoch - The Hadron epoch started 20 microseconds after the Big Bang and lasted from 10^-6 seconds until one second. The universe was now around 1 trillion degrees which allowed quarks to combine and form hadrons. Hadrons are subatomic particles made up of quarks, anti-quarks, and gluons. There are two categories of known hadrons: baryons and mesons. Most of the hadrons and anti-hadrons were eliminated in annihilation reactions, leaving a small residue of hadrons. Upon elimination of anti-hadrons, the Universe was dominated by photons, neutrinos and electron-positron pairs.
- Lepton epoch - The Lepton epoch commencing about 10^−5 s after the Big Bang, in which the various kinds of lepton were the main contributors to the density of the Universe.
- Photon epoch - The photon epoch was the period in the evolution of the early universe in which photons dominated the energy of the universe.
Matter era:
The period in the evolution of the universe, beginning roughly 105 years after the big bang, when the universe had cooled to the point at which electrons and protons were able to form neutral hydrogen atoms, and continuing to the present time, during which matter, in the form of atoms, is dominant over radiation.
- Cosmic Dark Age - The cosmic dark ages were a time when the universe was enveloped by a fog of neutral hydrogen that trapped the light of the first stars and galaxies. The fog didn't lift until 1 billion years after the Big Bang, when the neutral hydrogen had been re-ionized and once again split apart.
- Galaxy epoch - From 370,000 years until about 1 billion years. After recombination and decoupling, the universe was transparent but the clouds of hydrogen only collapsed very slowly to form stars and galaxies, so there were no new sources of light, large galaxies were formed through a rapid gravitational collapse that would have resulted in huge bursts of star formation at early epochs, leaving behind galaxies that had rapidly exhausted their fuel to age quiescently until the present; these galaxies appear now as large collections of old, red stars, such as elliptical galaxies and the central bulges of spiral galaxies.
- Acceleration - Dark-energy dominated era begins, following the matter-dominated era during which cosmic expansion was slowing down. Messier 67 open star cluster forms. Three exoplanets confirmed orbiting stars in the cluster including a twin of our Sun. Lalande 21185, red dwarf in Ursa Major, forms. Proxima Centauri forms completing the Alpha Centauri trinary system.
Epochs of the formation of the solar system:
9.2318 billion years, Sun forms - Planetary nebula begins accretion of planets. 9.257 billion years, Solar System of Eight planets, four terrestrial Mercury, Venus, Earth, Mars evolve around the sun.
