I was watching Bill Nye the science guy on TV recently. He stated that the earth's insides are molten because they were really hot a long time ago and they just haven't cooled off yet. We all know that's rubbish. It's the natural radioactive decay of isotopes in the earth that keeps it hot. Why is this guy misleading children this way? I think it's because he doesn't want kids growing up to think that radioactivity is as natural as sunshine and rain. He'd prefer them to think its an evil byproduct of modern civilization. What do YOU think?