The universe is believed to have been form from a very dense fireball billions of years ago is called big bang.
The Big Bang was the moment when the universe began as a explosion of tiny, dense fireball. It is a cosmological model of the observable universe from the earliest known periods through subsequent large-scale evolution Measurements of the expansion rate of the universe place the Big Bang was at around 13.8 billion years ago. The model describes about how the universe expanded from a very high-density and high-temperature state. After initial expansion, the universe cooled sufficiently then allows the formation of subatomic particles, and later atoms.
The theory offered the explanation for a broad range of observed phenomena such as the abundance of light elements, the CMB, large-scale structure, and Hubble's law.
First, Hubble figured out that the Milky Way isn’t the only galaxy. Then Hubble discovered that the galaxies are constantly moving away from each other
Belgian astronomer Georges Lemaître used Hubble‘s amazing discoveries to suggest an answer about how did the universe begin? If the universe is always getting bigger, then long ago it was smaller. And long, long ago, it was much smaller. That means billions of years ago, everything in the universe was contained in a tiny ball that exploded!
Learn more about big bang https://brainly.com/question/11985627
#LearnWithBrainly
