Michael Casey, senior advisor at MIT's Media Lab and author of the Age of Cryptocurrency, spent 18 years at the Wall Street Journal -- a good portion of that covering currency markets. But he says it wasn't until he learned about Bitcoin that he really understood what money was. In this episode of Unchained, he explains why, plus discusses why he thinks China will play a key role in moving the world to a cryptocurrency- or blockchain-based trade settlement system, what that could mean for the U.S. dollar as a reserve currency and what he thinks is the most cutting-edge work being done in blockchain.