Nobel Laureate economist Robert Shiller is on a panel at Davos about digital trends in financial markets. Almost immediately he started talking about Bitcoin.

He says that he finds it to be an "inspiration" because of the computer science. But he's not into it as an economic advance. As a currency he says it's a return to the dark ages.

Shiller is a student and expert in the nature of bubbles, and he's adamant that Bitcoin is one. He says he's blown away by how much fascination Bitcoin has engendered, though it makes sense because human nature causes us to be interested in markets that exhibit extreme volatility.

Says Shiller: "It is a bubble, there is no question about it. ... It's just an amazing example of a bubble."

He added that he's "amazed by how people are so excited about it" and that he tells his students that "No, it's not such a great idea."