His book, A Brief History of Time , has been translated into 33 languages and has sold nine million copies. A Brief History of Time has been translated into 33 languages and has sold nine million copies. You're probably familiar with the generally accepted scientific answer to the first question. The Big Bang theory says that the universe began 12 to 15 billion years ago. As the gas expanded, it cooled and allowed the matter to condense into structures like stars and galaxies and formed the world as we know it today.
Observations support the theory.
For example, we know from observation that the further a galaxy is from us, the faster it is flying away. But, there is a big problem. That means that our standard physics theories, like Einstein's general theory of relativity, can't deal with the start of the universe. So, scientists use two partial theories to describe the start of the universe. However, the theories are inconsistent with each other.