Why is this evidence that our planet is young and still changing?

Answer 1

I believe your missing the first half of the question but i think i can answer it anyway. The question is usually in regards to the earths core and how it is still molten at its center and spinning. As the core of the earth cools down it will stop spinning as fast from heat energy being lost to the system and loss of properties from that molten iron which deal with magnetism and electric charge. The sub surface of the earths crust helps exert spin on the core and vice versa. Without these attraction forces when the core cools they will show change.