Reading your most recent book, Do Polar Bears Get Lonely?, I was intrigued by the question: What's the highest level someone can free-fall? (or marked above as Free-Falling) and therefore wondered what would happen if you were to do jump unassisted.
If I was to take a huge heat-proof tube and stick it through the very centre of the earth and then jumped down it, what would happen when I reached the middle? Would I float at the very centre?