Photo: Jemal Countess/Getty Images Worrying about debt is, in a very real way, worrying about power. Ancient Rome was weakened by its debts, as was the Soviet Union . In the case of the United States, concerns about the $35 trillion national debt — now proportionately higher than at any time in history, including a huge World War II spike — tends to lead to anxiety that the U.S.’s global influence will wane as it has a harder and harder time convincing bondholders (the hedge funds, banks,