Here's a mental experiment for you. Imagine that the FRS instead of just putting money into database somewhere instead printed money certificates and then buried them in disused coal mines. Would that be any different from gold?
"Tangible" currency is an incredibly stupid idea, peddled be cretinous quacks of economics. The greatest achievement in economy (sadly ignored now) is that money in itself is a _tool_ that can be controlled.
The current Great Recession has shown time and time again that "hard money" approach just doesn't work. And trying to use it to make predictions fails miserably.