Eli5: how does for over 4.5b years the earths core still hasn’t cooled off?

Question

Eli5: how does for over 4.5b years the earths core still hasn’t cooled off?

In: 6

Answer 1

There are a lot of radioactive elements down there and their decays generate heat. The only way that can escape is to reach the surface and radiate sway. That takes a long time and heat is still bring generated, and will be for a long time to come