Public Debt

[Naji Dahi]

http://www.publicdebt.treas.gov/opd/opdpdodt.htm

I am very intrigued about the 6 trillion dollar debt that the US has. How
long can a country function as a superpower with such a massive debt. It is
more than 60% of the GDP. When will the "piper be paid" so to speak.

Is this sustainable in the long term? Help me understand this?

Thanks

Naji