The Big Bang theory is the prevailing scientific explanation for the origin and evolution of the universe. It proposes that the universe began as a hot, dense, and extremely small singularity approximately 13.8 billion years ago. This singularity contained all the matter, energy, and space that exist in the universe today.
According to the Big Bang theory, the universe underwent a rapid expansion known as cosmic inflation. During this inflationary period, the universe expanded exponentially in size, cooling down and allowing particles to form. As the universe continued to expand and cool, matter and energy began to interact and form the building blocks of galaxies, stars, and other celestial structures.