(Credit: Bank Artist/Shutterstock) A nuclear-armed Pakistani aircraft crashes just over the Indian border and the situation is about to spiral out of control. In Washington D.C., nuclear physicists and geopolitical analysts belonging to the Bulletin of the Atomic Scientists are meeting to decide whether to advance the “Doomsday Clock” ahead by two minutes. The Doomsday Clock is a symbolic representation of the level danger on planet Earth, and moving it ahead two minutes would take it to two minutes before midnight — two minutes before the end. This fictional scenario played out on a recent episode of Madam Secretary, but the Clock has been used as a snapshot of the dangers we face for well over five decades. But how do the hands on the Clock tick?