THE BIG BANG THEORY

An incredible explosion called the Big Bang is believed to have created the universe. Observations of the galaxies and the heat radiation from space have helped confirm this theory. Astronomers are now working to explain exactly what happens from the point of the Big Bang explosion which created everything in today's universe- matter, energy, space and time- to the present universe with its galaxies, stars planets and us.

Origin of the Universe

One of the most difficult problems that the scientists were facing in the 20th century was to explain the origin of the universe. The Universe is ever changing, but the real question here is from what and to what? The steady state theory suggests that the universe had neither a beginning nor an end. The alternative and now the generally accepted theory is the Big Bang Theory, which  proposes that the universe was created in an explosion 15 billion years ago. From the very small and simple beginning it has grown vast and complex.

The Steady State Theory

In the late 1940's the steady state theory was as popular as the Big Bang theory. It proposed that the universe looked the same from a long time. Although expanding, it would stay unchanged and would always be in a perfect balance. Materials were being continuously used up to keep the density of the universe constant. But as the proofs of the Big Bang theory were discovered, this theory was abandoned.

The Big Bang Theory

All matter was created in the Big Bang. The explosion started pushing everything away and the universe has been expanding ever since, and as the universe expanded the temperature dropped. After a fraction of second following the explosion, the 1st tiny particles began to form. By the time the Universe was minutes old it consists of 75% hydrogen & 25% helium were present and everything that exists now the galaxies, Earth, the stars, and life were created with the help of these elements.

Structure of the Universe

The most common object in the Universe is the star. There are billions and billions of them. At least one of them, the sun- has planets, and one among the planet has life in it- the Earth. On the face of it the stars, the planets and the human beings appear to be very different, but all of them have the same chemical composition and are affected by the laws of science, such as gravity, electromagnetism etc. By studying the constituents of the universe and understanding its laws, scientists are trying to build up a picture of the Universe and discover it's parts which may enable them to predict the future.

Expanding Universe

In the 1920's analyzing straight from the galaxies showed that the galaxies are moving away from Earth. This is true for galaxies in every direction from earth. Over time, Universe is becoming larger and less dense. The idea that the Universe started in an explosion from a single point and grew out of the observation proves that the universe is expanding.

Future of the Universe  

Nobody is quite certain about what is going to happen in the future of the Universe. At present it is expanding and becoming denser. Most astronomers believe that there will come a time when it will stop expanding, but there is a disagreement about what will follow; it is still uncertain that when that time comes will the Universe live on or wither and die or start to contract.

Big Crunch

The Universe may end in a Big Crunch if it starts to contract until it is hot and dense once more, but even this may not mean the end of the Universe. The big Crunch may also be followed by another big bang and a whole new cycle may begin again.