So, I think the headline is a little misleading. The article talks about the core spinning in relationship to the earth's spin. So, the disputed claim is that i

So, I think the headline is a little misleading. The article talks about the core spinning in relationship to the earth's spin. So, the disputed claim is that it has been spinning faster than the earth, and it's going to be spinning slower than the earth. It's not stopping or reversing. As for what would cause it to slow down or speed up with relationship to the speed of the planet's spin, they just say "magnetic and gravitational forces", whatever that means.