It is always a mystery about how the universe began, whether if and when it will end. Astronomers construct hypotheses called cosmological models that try to find the answer. There are two types of models: and Steady State. However, through many observational evidences, the theory can best explain the creation of the universe. The model postulates that about 15 to 20 billion years ago, the universe violently exploded into being, in an event called the . Before the , all of the matter and radiation of our present universe were packed togethe ....