Imagine there is nothing. Absolute nothingness. No air, no light, no human, no planet, no stars, no space and even no time. This is the time when it all began. The birth of the entire universe. The birth of time.
Most of the scientist of 20th century thought that the universe was infinite and ageless. But by the help of Albert Einstein and Edwin Hubble we got a better definition of the birth of the universe and it's structure. Also the discovery of the cosmic microwave background radiation made the Big Bang as the most accepted theory.
Let's talk about the very first moment when the universe came into existence. Firstly we have to keep in mind that the Big Bang was not an explosion. It was an expansion. The universe started very small and quickly expanded in every direction. Space expanded into itself. Because there was no outside of the universe.
10^-35 second after the birth the Infation started.
10^-32 second after the Big Bang it was the Quark Era. From Gluons pairs of Quarks were created. Those Quarks destroyed each other and created more Gluons. Matter and Antimatter was in a war. But Matter became victorious. Also in that time the universe was very very very hot and dense.
10^-9 second after the Natural Laws were created. The four forces of nature was born in that time.
- Strong Nuclear Force
- Weak Nuclear Force
- Electro Magnetic Force
- Gravity
The cycle of Quarks and Gluons stoped and the diameter of the universe stretched to 1 billion kilometers.
10^-6 second after it was the Hadron and Lepton Era. Quarks created new particles Hadrons and Leptons like Protons and Neutrons.
1 second after it was the Nucleosynthesis Era. The universe was cold enough to form the first atoms of Hydrogen and the diameter was 100 billion kilometers.
After that the Hydrogen gas clouds participated in nuclear fusion and made the first stars of the universe. Finally there was light. Countless Galaxies were formed from those stars. The universe expanded much more quickly. Also rate of the expansion is accelerating as we speak. The Big Bang happened 13.8 billion years ago and this is considered as the age of the universe.
This is a very simplified explanation of the birth of the universe. It's much more complicated than this. If you want to know more go to the Wikipedia page. I will post more episodes on our fantastic universe. So follow me if you are interested.