The Big Bang Theory: Evidence, Implications, and Unresolved Questions in Cosmology

The leading scientific explanation for the origin of the universe is the Big Bang theory, according to which our universe began 13.8 billion years ago from an infinitely dense and hot point, expanding rapidly into the expanse we see today 1. The theory emerged from a historical shift from the previously known static universe models 2. Resultantly, it transformed cosmology in the 20th century. We will also go through the basics of Big Bang Theory and its key evidence, like Cosmic Microwave Background Radiation, Redshift of Galaxies, and Abundance of light elements present in the Universe, to make us understand how our universe evolved. Observational support remains based on these pillars: redshift, CMB and primordial element abundances. The paper also examines perplexing issues related to dark matter, dark energy, and the universe's first moments that remain unresolved. Inflation theory, the singularity problem and what (if anything) might have existed before the Big Bang is also covered. This paper shows a concise and engaging way of explaining the great Big Bang debate by interweaving it with the scientific discoveries of today as well as historical context, making this subject more accessible to all who are interested in humankind's efforts to uncover how the cosmos began. It also takes into account the involvement of modern-day technology and future research in either supporting or possibly redefining the way we look at the universe's origin and fate.