According to Odaily Planet Daily, Kent Smetters, head of the Wharton Budget Modeling Project at the University of Pennsylvania, believes that a "doomsday" will arrive in the United States between 2045 and 2050, a critical point for the US economy. By then, the cost of paying interest on the federal government's national debt will be so enormous that even massive tax increases will be ineffective. Smetters states that by then, the US government will be in a situation of explicit or implicit default, both of which will have catastrophic consequences. An explicit default would make the US a global defaulter. An implicit default could theoretically be achieved through debt monetization (leading to inflation) or cuts to Social Security and Medicare spending. Smetters says, "This is when panic begins to spread, and it's also when trust in the government is lost. This is also the cause of the destruction of other societies. Tracing back to Rome, France, Spain, England, and Germany, almost every empire collapsed because of debt." (Jin Shi)