Here is a bit of Cold War trivia: Did you know that the Soviets actually had a real doomsday device? If you didn't, don't worry; even former CIA Director James Woolsey--until recently--wasn't aware. 

Originally known as Perimeter, but often referred to as Dead Hand, Moscow's doomsday device was intended to ensure that the Soviets could respond to a US attack even if its military command structure was wiped out. 

Here is how it worked: Dead Hand was equipped with sensors to detect both seismic activity and radiation in the atmosphere. In the event that either sensor registered a reading indicative of a nuclear attack, Dead Hand would send a message to Soviet General Staff. If the message bounced back because the communication line was down, the system would then send the necessary launch codes directly to lower level commanders at each Russian missile facility bypassing the traditional human chain of command. 

The argument for such a system is that it lessens the chance of an accidental launch by taking the pressure off leaders to respond at the first sign of attack. Retaliation is assured, so there is no need to launch your missiles when you are 50/50 on whether the other guy actually launched his. The computer will take care of the whole revenge thing whether you are around or not. 

The real shocker is that Dead Hand isn't just a piece of Cold War trivia. It remains a part of Russia nuclear defense strategy to this day. Want to learn more? Check out Nicholas Thompson's excellent new article on the origins and use of Dead Hand in the most recent issue of Wired Magazine.