At that time, the entire universe was inside a bubble. This bubble was very small and it was incredibly hot. Then the bubble suddenly exploded and the universe was created.
According to this theory, time and space began with the Big Bang. Nobody has discovered what was before it. In less than a second, the universe grew from a single atom to bigger than a galaxy. It has not stopped growing. Since then, the universe has grown and grown at a very high speed.
There are millions of galaxies and ours is the Milky Way. Other galaxies are billions of light years away and there are more that astronomers have not yet discovered. So… Is there life on other planets? Have aliens ever visited our planet? Can people from Earth live on other planets? These are just some questions astronomers have not answered yet. And their research goes on…