I'm a little bit fuzzy on the whole thing, myself. How can the Earth expand unless it creates matter? The amount of matter that collects from spacedust is a tiny fraction of an amount of the Earth's mass.

You suggest that the Earth started expanding after the planets formed and cooled down? How is this mass created? The Earth doesn't have any processes of which I'm aware of that allows it to grow. You'd have to have a hollow planet expand like a balloon. The Earth would have a much lower density is had been expanding than it does now.

It's like Johnny Cochcran and the Wookie defense!