Step 1: Understanding the Concept:
The Big Bang Theory is the leading cosmological model explaining the existence of the observable universe from its earliest known periods through its subsequent large-scale evolution.
Step 2: Detailed Explanation:
The theory proposes that the universe began from a singular, extremely hot, and dense state approximately 13.8 billion years ago.
From this initial singularity, the universe rapidly expanded and cooled, allowing the formation of subatomic particles, and eventually simple atoms.
Giant clouds of these primordial elements later coalesced through gravity to form stars and galaxies, including our Milky Way.
The origin of the Solar System and the Earth is explained by a later process called the Nebular Hypothesis, which occurred about 4.6 billion years ago.
Step 3: Final Answer:
The Big Bang Theory relates to the origin of the Universe.