T he universe is vast of which our galaxy is only a small part. We have the sun, planets, stars; every planet has a different number of moons, asteroids and meteors.
But have you ever wondered how did it all begin? How the universe did come into existence? This universe is governed by laws and rules that hold the solar systems together. Without the universe, we would not have had physics or chemistry or any kind or law or life. It is the curiosity of humans that give them the ability to look beyond the present.
What is it?
The big bang theory is an explanation that shows the origin of the stars, planets, galaxies and the universe as a whole. Scientists believe that the Big bang was the very beginning of the creation of this universe. Scientists state that the big bang occurred about 13.73 billion years ago.
Scientists believe that the big bang started with nothing – no space, no matter, no time and no energy. There was a very tiny, hot point, consisting of matter which had the potential to become something. This point then burst into the creation of the Universe. This Bang started time, created space and energy.
Atoms began to form as soon as the point burst. After a certain period of time, galaxies begin to form. Some billion years later planets began to form and after some more millions years later, life started to form on Earth.
Scientists like Stephen Hawking, George Ellis and Roger Penrose have studied and researched on the big bang theory. They believed that Big bang was the reason why space and time were created. These three scientists created and performed mathematical calculations to prove their theories.
Some other scientists believe that maybe there was a universe before the big bang as well. Since universe has the capability of expanding and contracting, this old universe might have collapsed and later might have bounced back with a new big bang. No one knows for sure the real time when the Universe came into existence or when the Big bang happened.
But one thing that scientists know for sure that something created a very hot spot to burst and expand into this Universe that we are in today.
The moment the big bang happened it let loose a large amount of energy into the Universe. The Universe started expanding and getting bigger and bigger, making more space. Electrons and protons came into existence. Gravity came into existence. The protons and electrons which got lost in space, bound together to form hydrogen atoms. These atoms formed nebulas, a group of atoms and molecules, which then developed into stars.
THE BIG BANG
Most astronomers believe the universe began in a big bang about 14 billion years ago. At that time, the entire universe was inside a bubble that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine.
Then it suddenly exploded. The universe that we know was born. Time, space and matter all began with the big bang. In a fraction of a second, the universe grew from smaller than a single atom to bigger than a galaxy. And it kept on growing at a fantastic rate. It is still expanding today.
As the universe expanded and cooled, energy changed into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old.
Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, forming hydrogen and helium nuclei.
After 300,000 years, the Universe had cooled to about 3,000 degrees. Atomic nuclei could finally capture electrons to form atoms. The universe filled with clouds of hydrogen and helium gas.
Five interesting facts about the big bang theory
Our universe is just a small part. There are many other universes exist. We live in a Multi-verse. This idea came from the big bang which might have given rise to bubble like structures which expanded in their own time.
Astronomer Edwin Hubble, in 1920s, discovered that the universe is not static. It is expanding and contracting continuously.
There is a dark energy that is making the Universe expand and accelerate at a larger rate than it did many years ago. There are many galaxies apart from our milky-way, that are moving further and further away.
The universe is infinite. It has no end. Thus scientists believe that the universe is not a closed sphere, but as flat as a sheet of paper and has no boundaries.
According to the scientists the planets, stars and galaxies include only 4 percent of what a universe consists of. 96 percent of the things in the universe cannot be seen.