The whole clock is kind of ridiculous.  There's no metric to it at all.  It's just the opinion of a bunch of guys.  Their whole reasoning is "a more hopeful state of world affairs"<p>The fact that a Doomsday clock that was designed to warn against the problem of nuclear weapons is being moved back mere months after Iran decided to defy the UN and start building another uranium enrichment plant should tell you how much of a crock this is.