If America defaulted on its debt, would US citiznes starve to death and would the world completely collapse?

Top US experts like Pat Robertson and Gerald Celente have said that if the debt ceiling isn't raised, we are going to default from lack of money cuts, which will turn us into an underdeveloped nation into a third world country just like Zimbawe.....is this true, or just Pat trying to scare people into the 700 club again./ idk, im freakin out, please give FACTS!!!!!!!!!!!!!!