The Big Bang Theory is the leading scientific explanation for how the universe began. It proposes that the universe started as an extremely hot, dense point — often called a singularity — approximately 13.8 billion years ago. From this state, the universe began to expand rapidly, not as an explosion in space, but as an expansion of space itself.
Key Features of the Theory:
- Initial Singularity: At time zero, all matter and energy were concentrated in an incredibly small, hot, and dense region.
- Expansion: The universe has been expanding ever since that moment. This expansion continues today and is measurable through the redshift of light from distant galaxies.
- Cosmic Microwave Background (CMB): Leftover radiation from the early universe, discovered in 1965, provides strong evidence for the Big Bang. It’s a faint glow still detectable in all directions.
- Element Formation: In the first few minutes after the Big Bang, the universe cooled enough for nuclear reactions to form light elements like hydrogen, helium, and lithium, a process known as Big Bang nucleosynthesis.
Misconceptions:
The Big Bang wasn’t an explosion in space — it was the expansion of space itself. Every point in the universe is moving away from every other point, not from a central explosion site.
The Big Bang Theory has been confirmed by multiple lines of evidence and forms the foundation of modern cosmology, helping us understand the universe’s origin, structure, and fate.