The Big Bang theory is the leading explanation for how our universe began. It suggests that about 13.8 billion years ago, all the matter, energy, space, and time were compressed into an incredibly hot, dense point called a singularity. Then, in an instant, this singularity began to expand rapidly in a massive explosion—or more accurately, an expansion—marking the birth of the universe as we know it.

In the moments after the Big Bang, the universe was a seething hot soup of particles, which gradually cooled down enough to form atoms. Over billions of years, these atoms gathered together under gravity to form stars, galaxies, planets, and eventually life. The expansion of the universe continues even today, and scientists can observe this through the redshift of distant galaxies and the cosmic microwave background radiation—the faint afterglow of the Big Bang still detectable across the universe.

The Big Bang theory revolutionized our understanding of the cosmos by providing a framework for how everything started from a single point and evolved into the vast, complex universe we see today. It raises profound questions about the nature of space and time and inspires ongoing exploration into the origins and ultimate fate of the universe. Simply put, the Big Bang is the cosmic story of how everything—from the smallest atom to the largest galaxy—came to be.