The universe is a name that was given to the vast space that contains everything we know (and don’t know).
The name might confuse some into believing that a huge explosion occurred and particles were shattered in all directions. There was no explosion but rather an expansion of the universe
The universe was ‘born’ about 14 billion years ago in a hot maelstrom known as the big bang.
Evidence of the big bang
The universe stretched the wavelength of the radiation emitted when it was quite young. It had much higher-energy and shorter wavelengths but now appears as longer-wavelength microwaves .
From the most simplest beginnings to the complex universe that has been formed in this era.
The big bang has many different phases. The early stages
The beginning was so cataclysmic that it is impossible to look back beyond the creation.
Planck era: This era begun at approximately 0 seconds and is possibly the absolute beginning of of time. The four fundamental forces ( electro magnetic , weak nuclear, gravity and strong nuclear) were unified into one force. The idea of the four forces unified goes back to the ancient Greeks .
Grand unification: The force of gravity separates from the other forces. This was a period when the particle energies were so great that the leptons and quarks started forming.
Inflation: The strong nuclear force separates and the universe undergoes rapid expansion ( the universe expands from a size of a pea to that of a grapefruit). The grand unification was broken. A hot, dense quark-gluon plasma known as quark soup was distributed across the universe.
Electroweak Era: The electroweak force into two forces (weak nuclear force and electro magnetic force). This resulted in four distinguished forces in the universe. The weak force explains beta decay (A nuclear radiation in which a neutron turns into a proton inside the nucleus). The electro magnetic force is carried by massless photons. A large number of particles are created including W,Z and the Higgs boson. The universe is entirely radiation to support the matter. This unification opens up a possibility that under certain high-energy conditions, the forces will be unified. Thus, the search for the theory of everything continues.
Quark Era: Quarks and leptons ( mostly electrons and neutrinos) form and the four forces developed into their present forms. The matter and antimatter annihilate each other. The quarks that have not been annihilated will combine to form matter.
Hadron Era: The temperature cools down and the quarks combine to form hadrons (baryons: protons and neutrons). Electron and protons collides and forms neutrons and massless neutrinos are created.
Lepton Era: Most the the hadrons and anti hadrons annihilate each other. The leptons and anti leptons dominate the mass of the universe.
Nuclei synthesis: The protons and neutrons combine to form nuclei of the simplest element (hydrogen).
Photon Era: The universe cools down and is filled with plasma. The universe is now dominated by photons.
Recombination: Hydrogen and helium ions capture electrons and with the electrons now bound to them, the universe finally becomes transparent to light.
Until about 700 000 years after the big bang, the universe mostly consisted of radiation. Thermal equilibrium of matter was ensured by the absorption of photons. This also prevented matter
from forming clumps or even neutral hydrogen atoms.
At about 700 000 years, the protons could bind to electrons to form hydrogen atoms. The universe became transparent to photons.
Dark Era: The period after the first atoms and before the first stars forms. The universe is dominated by dark matter.
Reionization: The first quasars( Supermassive black holes that accrete matter) form from gravitational collapse.
Star formation: The first stars appeared about 200 million years after the big bang. They were about 1000 solar masses and made completely of hydrogen and helium. They dispersed new chemical elements throughout their lives. Carbon, oxygen, iron and silicon were formed from nuclear fusion in the core of the stars (the elements of life was created in the core of stars).
Galaxies: These are huge collections of stars. The first galaxies began 500 million years after the big bang. The first galaxies are building blocks of the galaxies we see today.
Our solar system
Our sun was formed from the debris of earlier stars. Our solar system formed about 5 billion years ago.
The key to understanding the early universe lies in the understanding of the elementary particles.