Resumo de Begining Of The Universe

THE BEGINNING OF THE UNIVERSE
THE BIG-BANG THEORY

Time space and matter all began so astronomers believe in one truly momentous event: a hot, dense explosion called the Big Bang which took place between 10-20 billion years ago. In the first few millionths of a second, as the universe expanded incredibly quickly, many complicated events happened.
The first steps in the creation of matter itself are of immense interests to scientists everywhere. Many important experiments are conducted in order to study these events ? a field of science known as particle physics.
Atoms are the building blocks of all kinds of matter, from grains of sand to people from planets to stars. Although atoms are very tiny, they are composed of even smaller particles. It is these particles that were made in the Big Bang, eventually forming galaxies billions of years later. Such was the violence of that event that galaxies, or cluster of galaxies, are still rushing apart in an ever-expanding universe.

The Birth Of Atoms
Immediately after the start of the Big Bang, space rapidly expanded for a very short time. This process which lasted for the minutest fraction of second in called inflation. After that, expansion began to slow down and different kinds of particles including quarks and electrons made their appearance. Just one millionth of a second after the birth of the universe, the quarks had clumped together to form new particles called protons and neutrons.
After a hundred seconds some of the protons and nearly all neutrons gathered into bunches consisting of 2 protons and neutrons. Eventually each bunch or atomic nucleus captured 2 electrons to form a helium atom and each remaining proton captured a single electron to form a hydrogen atom. The first building blocks of matter had been born.

The Birth Of Galaxies
By the time atoms of hydrogen and helium had formed, the searing heat of the Big Bang had cooled down and the dense gas of earlier times was becoming more thinly spread out as the space continued to expand. Gradually though perhaps a billion years later huge clouds of gas held together by gravity began to collapse to form galaxies and clusters of galaxies. As time went on stars began to be formed in the galaxies and the galaxies began to form familiar elliptical and spiral shapes. About 5 billion years ago, in our own Milky Way Galaxy the Sun was born. Planets began to form around the Sun, and one of them was our home the Earth.

The Big Crunch ? Universe Open OR Closed
The expansion of the universe is gradually slowing down. Galaxies may continue to move apart forever. However, gravity a force of attraction between bodies in the universe ? may eventually halt the expansion. Then, the galaxies will start to fall together until everything collides in a ?Big Crunch?. No one can tell whether the universe is open (ever expanding) or closed (destined eventually to collapse upon itself).

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