The Birth
The universe began with a particle. The universe was very dense and very hot. Eventually, it exploded and gradually expanded. It spread across space carrying matter with it. The universe formed in just a quick second.
This happened approximately 13.7 to 14 billion years ago.
Scientists are unsure if the universe is an open universe or a closed universe. If it's open, then the universe will continue to keep on growing. But if it's closed, it could later reduce to the size of a molecule again and blow up. Then everything would start over. Although, these ideas haven't been confirmed so scientists will continue to research and find out what really happened.
This happened approximately 13.7 to 14 billion years ago.
Scientists are unsure if the universe is an open universe or a closed universe. If it's open, then the universe will continue to keep on growing. But if it's closed, it could later reduce to the size of a molecule again and blow up. Then everything would start over. Although, these ideas haven't been confirmed so scientists will continue to research and find out what really happened.