What is exactly universe? The universe is commonly defined as the totality of everything that exists,including all physical matter and energy, the planets, stars, galaxies, and the contents of intergalactic space,although this usage may differ with the context. The term universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world, or nature.

Observations of earlier stages in the development of the universe, which can be seen at great distances, suggest that the universe has been governed by the same physical laws and constants throughout most of its extent and history.Our universe, the galaxies, solar system, planet Earth — land, sea, air, life — where did they come from? Astronomer Edwin Hubble believes our universe once was very tiny. Take a journey through space and time to discover how the universe was born.