When we were children, we rarely stopped to think about how we came into existence. But as we grew older, many of us started asking bigger questions. Where did we come from? How did everything around us begin? And where were we before the world we know today existed?

One of the biggest scientific ideas that tries to answer these questions is the Big Bang. It describes a universe that began in an extremely hot and dense state and has been expanding and changing for about 13.8 billion years.

The Big Bang was not simply a giant explosion happening inside an empty space. Instead, the universe itself was expanding. As it expanded, it cooled, and the conditions of the early universe changed dramatically.

In the early stages of the universe, tiny particles began to form. Among them were the building blocks that later became protons and neutrons. As the universe continued to expand and cool, these particles eventually combined to form the first atomic nuclei.

But the story did not end there. Hundreds of thousands of years later, the universe had cooled enough for electrons to combine with atomic nuclei and form the first atoms. Much later, gravity brought clouds of gas together, eventually creating the first stars and galaxies.

Over billions of years, stars created heavier elements, galaxies continued to evolve, and new generations of stars and planetary systems formed. Somewhere in this enormous cosmic story, our own solar system and Earth eventually came into existence.

But one question still remains: What existed before the Big Bang, and how did that extremely hot and dense early state eventually become the universe we see today?