I didn't get that far down, no.

I mean I could see that it's full of uncertainty, I did hear you when you said there's a Nobel prize up for grabs for solving this.

The fact of the matter is though, the heat is there. I'm not going to speculate why it shouldn't be there, because it is there, and it's there because it should be. I'm going to try and speculate why it is there.

I just did a google search for "half life of uranium". We're good for another billion years if uranium 238 is plentiful, and it seems that it's the most abundant form of uranium in the planet. Plutonium is realtive short, potassium can get over a billion years.

So the plutonium and potassium should have decayed by now. If it hasn't, well then the planet must be producing the stuff.