Why the Universe is expanding and to what extent it will expand?
Dear Student!
Long back in about 1929, an astronomer, Edwin Hubble discovered that the universe is expanding. Once scientists understood this they realized that it would have been really small at the previous time. At some point in the past the entire universe would have been one small point. Thus it is believed that there was a Big Bang that led to the expanding universe. Astronomers believe that there are three possibilities that the universe can end up with.
It can either go on expanding forever, or may be at much much later time stop expanding and everything stays where it is. The last possibility that they ponder over is that there might be a Big Crunch antagonistic to the Big Bang when the entire universe will collapse. And then there comes another Big Bang.
Research is going on and scientists will soon be able to find what the fate of the universe would be.