Explain · Like I'm five version
The Big Bang in terms of opening a can of fizzy pop
Have you ever wondered how the whole wide world popped into being?
The Big Bang is exactly like opening a very fizzy can of pop on a hot summer day. Before you open the tab, all the bubbles are squished together in a tiny, tight space. The universe was once just like that, squashed into a tiny dot that was super hot and very crowded. When the universe started, it did not just sit there, it went pop and pushed everything out super fast.
When you pull the tab, the bubbles rush out to find more room. They start as a little fizz at the top and then spread out everywhere across the kitchen table. The universe did the same thing by growing bigger and bigger every single second. It is still growing right now, just like how the fizz keeps moving until the bubbles finally find a place to rest.
Everything we see, from the big yellow sun to your favourite bouncy ball, is made from the bits that came out of that first big pop. The hot fizz cooled down as it spread out, turning into all the stars and planets we see in the sky at night. It is a bit like how the pop gets less fizzy and more still as it sits in your glass.
Where the analogy breaks downThe universe does not stop being fizzy when it gets old, and it does not need a cupboard to stay in.