Yesterday I received my Essentials of Geology textbook for college, and I looked over it a bit. But then when I was really high at night, I read most of the first chapter, and learned how the Universe formed. It is some crazy shit, and I was surprised I didn't know it before, so I will explain it here. It all begins with the big bang, which started with a huge amount of energy condensed in a hot ball. There were no atoms or molecules, it was just pure energy. Then it "exploded" and expanded very rapidly. During the course of this expansion, the energy quickly took form into the most basic atoms: Hydrogen. Through something known as big bang nucleosynthesis, the atoms collided into each other so hard they fused, creating helium. Therefore, essentially all the matter in the Universe was hydrogen and helium. The hydrogen and helium would come together in large clouds known as nebula. Gravity would pull the nebula in on itself, until it began to get so hot in the center that fusion reactions could begin. This is the birth of a star. Now here is where things get interesting. The stars that formed were powerful enough to fuse atoms into higher elements, which is known as stellar nucleosynthesis. This process can produce elements with atomic numbers higher than 5, while big bang nucleosynthesis was mainly limited to hydrogen and helium. Essentially, stars are what produced the higher elements that we see around us today. Many elements are so large that they cannot be produced during the lifetime of a star, but during its death, when it explodes in a supernova. This is when the heaviest elements are released. As the Universe evolved, the first generation of stars gave way to larger atoms (new elements) that produced new stars, and then those new stars gave way to even larger atoms. What is most amazing is that since all the heavier elements were composed in stars or during supernovas, that means that all of us, and all of this world, was once inside a star, being created through stellar nucleosynthesis. That's crazy as shit! It is also pretty interesting how the planets formed, but I feel this thread is long enough as it is, so thanks for reading!