"And it is We Who have constructed the heaven (universe) with might, and verily, it is We Who are steadily expanding it". (Qur'an, 51:47)
At the beginning of the 20th century, the Russian physicist Alexander Friedmann and the Belgian cosmologist Georges Lemaitre theoretically calculated that the universe is in constant motion and that it is expanding. From the moment of the Big Bang, the universe has been constantly expanding at a great speed. Scientists compare the expanding universe to the surface of a balloon that is inflated.
This notion was confirmed by the use of observational data in 1929. While observing the sky with a telescope, Edwin Hubble, the American astronomer, discovered that the stars and galaxies were constantly moving away from each other. This discovery is regarded as one of the greatest in the history of astronomy. During these observations, Hubble established that the stars emit a light that turns redder according to their distance. That is because according to the known laws of physics, light heading towards a point of observation turns violet, and light moving away from that point assumes a more reddish hue. During his observations, Hubble noted a tendency towards the colour red in the light emitted by stars. In short, the stars were moving further and further away, all the time. The stars and galaxies were not only moving away from us, but also from each other. A universe where everything constantly moves away from everything else implied a constantly expanding universe. The observations carried out in the following years verified that the universe is constantly expanding.
In order to gain a clearer understanding of this, let us imagine the universe to be the surface of a balloon being inflated. In the same way that the more the balloon is inflated, the further away the points on its surface move from one another, celestial bodies also move away from one another as the universe expands. This was theoretically discovered by Albert Einstein, regarded as one of the greatest scientists of the 20th century.
Modified from: www.miraclesofthequran.com