How Did The Universe Begin // From the Big Bang to the Present

The Big Bang theory says that more than 13 billion years ago, the universe came from a single point that was so hot and thick that it was hard to imagine. This point is called a singularity. It didn't happen in a place that was already there. Space itself started to get bigger and cooler because of it.

It explains a lot of what scientists see through telescopes on the ground and in space. It shows why other galaxies are getting farther away from us as space keeps getting bigger. It explains why the whole universe has a faint glow. (The glow is the extra heat from the birth of the universe, which has now cooled to just a few degrees above absolute zero.) In short, it is a very powerful and beautiful way to explain how the world we can see came to be.