What would be the problems of having one world currency?
It would actually be quite a bad idea. If the economies of two regions are decoupled, they should have separate interest rates. Changing interest rates is the best way we have to moderate the cycles of rapid growth and severe recessions we had until the Greenspan era in America, and similar reforms in Europe. If all regions of the world are on the same currency, they will all have to have the same interest rate, which means that the interest rates won’t be responsive to local economies.
