Many of you have heard of the Doomsday Clock — a decades-old analogue clock meant to symbolize how close we are to nuclear catastrophe. However far we are from midnight, we are told, is how close we are to disaster. More recently, it is also meant to incorporate the risks of catastrophic climate change. It was started by many of the scientists responsible for the creation of the nuclear weapon. And it is, and has always been, run by the Bulletin of the Atomic Scientists. The Bulletin just set the clock to 100 seconds to midnight — the closest it's ever been. On Twitter, Ryan remarked that he didn't think this exercise added much in the way of value. And so, a debate began. Ryan assembled a group to debate the Doomsday Clock (over Manhattans, appropriately). On one side, Miles Pomper of the James Martin Center for Nonproliferation Studies and Benjamin H. Friedman of Defense Priorities. On the other, Jon Wolfsthal and Sharon Squassoni, both of whom sit on the Bulletin of the Atomic Scientists' Science and Security Board. And Ryan served as an admittedly biased moderator.