The article explores how the economy behaves near zero interest rates. It looks at different scenarios, including one where prices fall and another where the economy switches between rising and falling prices. By analyzing data from the 2008-09 recession, the researchers found that keeping interest rates low can boost government spending's impact on the economy. In some cases, this can more than double the effect of government spending. However, if the economy is in a state where prices are unstable, the impact of government spending is smaller, and traditional monetary policy may not work as well.