After the Big Bang
Actually, the Cosmic Background Radiation is a major piece of evidence of the Big Bang. So, what happened to the universe after the Big Bang. As the universe continue to expand, the variation in density inflated to such a scale that gravity is able to take hold and start clumping together clouds of hydrogen and helium gas. And atoms of hydrogen and helium increasingly squeezed together, which means increasing pressure and increasing temperature. As core regions of gas clouds heat up, the atoms get jumpy, move faster and faster, and collide with ever-increasing ferocity. Eventually, it's ferocious enough to overcome the electric repulsion between the atoms. They fuse and the cloud officially becomes stars.
Our galaxy, the Milky Way formed from these galactic mergers with other galaxies that stopped around 10 billion years ago. Our galaxy is about 100,000 light years across. Everything we can touch, feel and see, even us, is debris floating around enormous stars in the vacuum of space. We may just be the ashes of dead stars, but those ashes hold the potential to arrange themselves in increasingly complex ways, from which the Earth and all it contains, can rise.
