The Big Bang theory represents cosmologists' best attempts to reconstruct the 14 billion year story of the universe based on the sliver of existence visible today. Different people use the term "Big Bang" in different ways. Most generally, it illustrates the arc of the observable universe as it thinned out and cooled down from an initially dense, hot state.

Big Bang can also refer to the birth of the observable universe itself — the moment something changed, kickstarting the events that led to today. Cosmologists have argued for decades about the details of that fraction of a second, and the discussion continues today

n this video, we're going on a journey through the true story of the universe's origin. From Isaac Newton's static universe to Albert Einstein's revolutionary theory of relativity, from Edwin Hubble's mind blowing discovery that the universe is expanding to the cosmic microwave background radiation that proved the Big Bang happened. But that's just the beginning of the story.

The Universe is all of space including everything that exists. Our planet, all other planets in existence, stars, and galaxies are all part of the universe. It was born more than thirteen billion years ago in the Big Bang. Scientists say that it is at least ten billion light-years in diameter. In this sense, the Universe means the Cosmos. The Universe is all time and space, i.e., spacetime. It includes all the galaxies, stars, planets, moons, and all other forms of energy and matter.

Science is the intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment.