Depending on the day, Amazon founder Jeff Bezos is either the richest or second richest human on Earth. And while he's trying to figure out how to use some of that money philanthropically, he announced today that construction has begun on the giant clock in the middle of nowhere that he put up $US42 million ($53 million) to build. The 10,000 Year Clock is intended as a symbolic reminder that we should consider the long-term impact of our actions.