Well, we know that virtual photons can be created out of thin air so why not virtual $? A 2013 dollar is about as substantial as a photon so why not? Moreover, as Steven (No God Needed) Hawking has theorized, a virtual photon created at the event horizon of a black hole can become 'real'. Since the US government is a black hole of spending, it makes perfect sense that it can turn virtual $ into real dollars!! viola!!