After the 2008-09 financial crisis, the world's major central banks undertook a giant monetary policy experiment to see whether quantitative easing or its variants could restart the world's economic engines. As much of the world keeps pumping money into its various financial systems, the U.S. Federal Reserve is moving in the opposite direction by raising interest rates. On Friday, all eyes at the annual central bankers' symposium will be on Federal Reserve Board Chair Janet Yellen to see whether her speech will give any indication of the Fed's next interest rate hike. Throughout the conference, which kicked off Thursday in Jackson Hole, Wyoming, the untested -- and disputed -- success of quantitative easing will be a topic of much discussion. ...