It is unknown how the universe began. but it's thought to have been extremely small, dense and hot at some point..
"If it were an explosion, it would have a center"- Physicist Paul Steinhardt
Then it's theorized that it became so small, dense and hot, that it "exploded" and rapidly expanded in all directions. It is thought to beinfinitely expanding in every direction and estimated to be expanding 67km/s
As the universe keeps expanding, the elements inside it continue to combine and create things such as stars, planets, galaxies.
And in one of these billions of galaxies, is earth.
On this planet called earth, there live curious creatures known as humans, who's curiosity push them into learning more about how the planet they live on and the ever expanding universe around it came to be.