The big bang time came into existence when the universe begins so the question what happened before? has no meaning. Space also came into existence. The big bang was not an explosion of matter true space – it was an explosion of space itself.
At first, the universe consisted of pure energy, but within a trillionth of a second, some of this energy turned into matter, farming a vast soup of subatomic particles (particles smaller than atoms). It took nearly 400,000 years for the particles to cool down enough to form atoms, and then another 300 million years before the atoms formed planets, stars, and galaxies. The expansion that began in the big bang continues to this day, and most scientists think it will carry on forever.
The universe began called a singularity: A point of zero size but infinite density.
1. The universe appears out of nowhere, at the start, the universe consists purely of energy and is infinitely dense and unimaginably hot – 10 billion trillion centigrade (18 billion trillion Fahrenheit).
2. Within a tiny fraction of a second, the universe balloons in size from trillions of x smaller than an atom size of a city. The rate of Expansion then slows.
3. The intense energy of the universe creates matter. At first, the matter is a soup of particles and antiparticles. This crash into and cancel each other out, turning back into energy. But some of the matter is leftover this will eventually turn into atoms and later stars and galaxies.
4. The universe is now about 1 microsecond old and hundred billion kilometers (60 billion miles) wide. The leftover particles begin to form protons and neutrons – the particles that today make up the nucleus of atoms. But the universe is too hot for atoms to form yet. Light cannot pass through the sea of particles show the young Universe resembles a dense fog.
5. After 379 Thousand Years, the universe cools enough for atoms to form. The universe is now a vast cloud of hydrogen and helium. Light can pass through space more easily, and the universe becomes transparent.
6. Half million years after the big bang, the matter is spread out almost evenly in the universe, but tiny ripples exist. Working on this d e n s e r patches, gravity begins pulling the matter into clumps.
7. At 300 million years, stars appear. Stars form when great clouds of gas are p England XI pulled into tight knots by Gravity. The pressure and heat become so intense in the dense pockets of gas that nuclear reactions begin, igniting the star.
8. Earth 500 million years, the first Galaxies are forming. Galaxies are enormous clouds of stars, held together by Gravity.
9. 5 billion years old, the universe consists of vast clusters of galaxies arranged in threads, with gigantic voids between them. The voids get ever bigger as space continues to expand. At 8 billion years, the expansion of the universe begins to accelerate.
10. Our solar system forms at 9 billion years old, the sun will expand in size and destroy the earth.
11. The universe will carry on expanding forever, becoming cold and dark everywhere.