How did the universe begin?

We know we live in a universe that is expanding. As time passes by and the universe expands, it gets bigger, colder, and less dense. This means that in the past the universe was smaller, hotter, and denser. All we see and are today came from this initial stage. The model that describes the evolution of our universe from this initial hot and dense phase is called the Big Bang model and compiles our understanding of our universe. However, this initial stage of the evolution of the universe is still a mystery to us and cosmologists have many theories to describe it! In this talk, we are going to discuss the early universe and the models developed to describe the initial evolution of our universe. We are going to discuss the main paradigm, called inflation, and explain how it gives us the universe we observe today. We are also going to discuss alternative models of the evolution of the early universe like bouncing cosmologies, where our universe did not have a beginning but came from a phase of contraction before our current expanding phase, and emerging universes. We are going to discuss the progress and efforts in cosmology to constrain these models and unravel the mystery of the beginning of our universe.