Origin of Universe

In our childhood there was always a question in our mind that who came first, the hen or the egg? similarly ,there was one more questions which makes our mind blow that how and when did our universe came and when did we know about it? And how this universe works and many more such questions. "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe” said Albert Einstein. Our universe is a full of an independent Ocean like our mind i.e there is no any boundary of the universe. So,Let's go for a dive in this infinite ocean. 

A Universe is everything from the tiniest particles to the largest galaxies, to the very existence of space - time and life , the spatial size of the entire universe is unknown, it is possible to measure the size of the observable universe, which is currently estimated to be 93 billion light-years in diameter and According to research, the universe is approximately 13.8 billion years old but how did it all begin. The origin of Universe is the origin of everything. Multiple scientific theories plus creation myths from around the world have tried to explain its mysterious Genesis. However the most widely accepted explanation is the Big Bang Theory. The Big Bang Theory states that the universe began as a hot and infinitely dense point, only a few millimetres wide. It was similar to a supercharged Blackhole. 

Big Bang explosion

About 13.7 billion years ago, this tiny singularity violently exploaded and it is from this explosion, this bang that all matters, energy,space and time were created. And now this is the time of evolution. This giant explosion hurled matter in all directions and caused space itself to expand. There were a two major stages of the universe's evolution called the radiation era and the matter era that helps to shape the universe. 

First came the Radiation era named for the dominance of radiation right after the Big Bang. This era is made up of smaller stages called epochs that occurred within the universe's first tens of thousands of years. The earliest is the Planck epoch, no matter existed at this time only energy and the ancestor of four forces i.e.

• Gravity
• Strong Nuclear Force
• Electromagnetic Force
• Weak Force

called Super force there. 

Planck epoch :-

• Temperature : 10⁴⁰ Kelvin
• Time after big bang : Immediate

At the end of the stage however a key event occurred in which gravity split away from the Super force. Next came the Grand unification epoch named for the three remaining unified forces of nature. This epoch ended when one of those forces called strong Nuclear force broke away.

Grand unification epoch :- 

• Temperature :10³⁶ Kelvin
• Time after big bang : 10^-43  second

Then the inflationary epoch began during which the universe rapidly expanded almost instantly it grew from the size of an atom to the size of a grapefruit. The universe at this time was piping hot and it churned with electrons , quarks and other particles. 

Inflationary epoch :- 

• Temperature : 10³³ Kelvin
• Time after big bang : 10^-36 seconds

Then came the electroweak epoch, when the last two forces electromagnetic and weak forces split off.

Electroweak epoch :- 

• Temperature : 10²⁰ Kelvin
• Time after big bang : 10^-32 second

During the next stage,the quark epoch, all of the universe's ingredients were present however the universe was still too hot and dense for subatomic particles to form.

Quark epoch :-  

• Temperature : 10¹⁶ Kelvin
• Time after big bang : 10-12 seconds

Then in the Hadron epoch, the universe cooled down enough for quarks to bind together and form protons and neutrons.

Hadron epoch :- 

• Temperature : 10¹⁰ Kelvin
• Time after big bang : 10-6 second

In the Lepton and Nuclear epochs, the radiation era's last two stages,the proton and neutron underwent a significance change. They fused and created a nuclei and in doing so, they created the first chemical element in the universe, Helium.

Lepton epoch :-

• Temperature : 10⁹ Kelvin
• Time after big bang : 1 second

Nuclear epoch :-

• Temperature : 10⁹ Kelvin
• Time after big bang : 100 second

The universe's new ability to form elements, the building blocks of matter caused the Matter era.Much as the name suggests the matters era is defined by the presence and predominance of matter in the universe. It features three epoch i.e. atomic epoch, Galactic epoch and Stellar epoch that span billion of years.  The firat was the atomic epoch.

Atomic epoch :-

• Temperature : 3000 Kelvin
• Time after big bang : 50,000 years

In this stage the universe's temperature cooled down enough for electrons to attach to nuclei for the first time called recombination. This process helped to create the universe's second element hydrogen. This Hydrogen along with helium atoms dotted the universe with atomic clouds. Within the clouds small pockets of gas may have had enough gravity to cause atoms to collect. These cluster of atoms formed during Galactic epoch became the seedling of galaxies.

Galactic epoch :-

• Time after big bang : 200 million years

Nestled inside those galaxies, stars began to form and in doing so they cued the latest and current stage of the universe's development, The Stellar epoch.

Stellar epoch :-

• Time after big bang : 3 billion years

The formation of star caused a tremendous ripple effect and helped to shape the universe as we know it. Heat within the stars caused the conversion of helium and hydrogen into almost all remaining elements in the universe. In turn those elements became the building blocks for planets,moon,life, everything we see today. 

The ecosystem of this independent ocean was only possible because of many stages of the universe's development while countless questions about the origin of our universe remain, it's only a matter of time for some long sought answers to emerge. 

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