What is the Big Bang?

I'd love to walk you through how the universe began! Before we dive into the deep cosmic history, I'd like to understand a little bit about what brings you here today.

What brings you to learn about the Big Bang today, and how familiar are you already with astronomy or physics?

I'm a beginner just curious about how everything started

It's great to have you here! Since you are curious about how everything started, we are going to travel back to the very beginning of time and space to see how our universe came to be.

Your path

Timeline of the early universe

Key evidence supporting the theory

Common misconceptions and modern context

A Universe in Motion

When most people hear the words "Big Bang," they instantly picture a giant, fiery explosion in the middle of empty space, like a cosmic firework going off in a dark room. But here is the real mind-bending secret: the Big Bang wasn't an explosion in space at all. It was the sudden, rapid expansion of .

Imagine a vast, infinite sheet of rubber. Instead of objects flying across this sheet, the rubber sheet itself is stretching out in every direction. Before this stretching started, about , everything that exists today—every star, planet, grain of sand, and even the space we occupy—was squeezed into a single, unimaginably tiny point. This starting point was hotter and denser than the core of any star.

A 2D coordinate grid with galaxy dots positioned at grid line intersections.

I have set up a visualization above to help you see how this stretching works. Notice how the "galaxies" aren't actually traveling through the grid; rather, the grid lines between them are expanding!

Would you like to explore an analogy that makes this stretching concept even easier to visualize?