Nobel prize winning economist Robert Mundell's theory of the op"optimal currency area" predicted that the adoption of a single currency would have more political consequences than simply keeping germany focused on european intergration . Adopting a single currency would in effect remove important economic tools (exchange rate adjustment rates, for example, a nation with a flexible exchange rate regime is free to lower interest tprates to stimulate economic activity . the lower interest would drive down the value of the currency , making domestc products more attractive and stimulating job creation