Nobody knows how the Universe began. The most widely believed scientific theory is called the Big Bang theory. The Big Bang theory suggests that all the matter in the Universe was suddenly created about 20 000 000 000 years ago. The matter began to fly apart. It then became grouped together to form galaxies. One of the reasons that astronomers support this theory is that the Universe is still expanding further and further apart from one another.
Other scientists have suggested that the Universe did not have beginning, but has exited forever. At the moment this is not a well-supported idea. Bit astronomers find out more and more about the Universe, they may change their theories about how it began.
Future of Universe
Scientists differ on how long the Universe will exist. Some of them believe that will go on forever - even after all the stars have ceased to shine. They hold that the Universe will be quite dark and cold then.
Bur other scientists believe that the Universe will go on expanding, no doubt. But ultimately it will reach a stage where further expansion will not be possible. This stage will be followed by period of contraction and the Universe will reach its original state to repeat the process of expansion again. This theory has been named the Oscillation theory.
According to the Oscillation theory the Universe will never cease to exist. It keeps expanding and contracting in turn again and again. Thus it will go on for all time to come.
