The question of what existed before the Big Bang and how the universe came to be is one of the most profound mysteries in cosmology. The Big Bang theory describes the expansion of the universe from an extremely hot and dense state, but it does not provide a clear explanation for what triggered the Big Bang or what preceded it. The concept of "nothingness" or the state of the universe before the Big Bang is a subject of speculation and ongoing scientific inquiry.
It's important to note that our understanding of physics and the laws of nature may break down when attempting to describe the conditions before the Big Bang. The singularity at the beginning of the universe, where all matter and energy were concentrated into an infinitesimally small point, represents a regime where our current theories are insufficient to explain what occurred.
There are several cosmological models and theories that attempt to address the question of the universe's origin, such as the concept of cosmic inflation or theories involving multidimensional spaces and branes. However, these models are still subject to ongoing research and are far from being conclusively proven.
Ultimately, the question of what existed before the Big Bang remains an area of active scientific investigation and philosophical contemplation. As our understanding of physics and cosmology continues to evolve, we may gain further insights into the nature of the early universe and its origins.