The next time you hear someone in the government use the word "billion" casually, think about it. A billion is a difficult number to comprehend. One advertising agency did a good job of putting that figure into perspective in one of its releases: A billion seconds ago it was 1959. A billion minutes ago Jesus was alive. A billion hours ago our ancestors were living in the Stone Age. A billion days ago no-one walked on two feet on earth. And a billion dollars lasts 8 hours and 20 minutes at the rate our government spends it...