On GPS this week, we explore the most important topic (the economy) with the most important economic voices. Fareed Zakaria talks to Nobel Prize winner Paul Krugman and Former IMF Chief Economist Ken Rogoff.

The show also turns a myth on its head. China’s not doing the U.S. a favor by buying its Treasury Bonds - the pleasure is very much China’s. We’ll explain.

All that, plus a fascinating look at America’s fractured relationship with Pakistan with the journalist Ahmed Rashid, and a smart, macro look at the London riots with two top British thinkers.

But first, why does Paul Krugman say space aliens could fix the U.S. economy? Here's an edited excerpt of what he and Ken Rogoff had to say:

Ken Rogoff: Infrastructure spending, if it were well-spent, that's great. I'm all for that. I'd borrow for that, assuming we're not paying Boston Big Dig kind of prices for the infrastructure.

Fareed Zakaria: But even if you were, wouldn't John Maynard Keynes say that if you could employ people to dig a ditch and then fill it up again, that's fine, they're being productively employed, they'll pay taxes, so maybe Boston's Big Dig was just fine after all.

Paul Krugman: Think about World War II, right? That was actually negative social product spending, and yet it brought us out.

I mean, probably because you want to put these things together, if we say, "Look, we could use some inflation." Ken and I are both saying that, which is, of course, anathema to a lot of people in Washington but is, in fact, what basic logic says.

It's very hard to get inflation in a depressed economy. But if you had a program of government spending plus an expansionary policy by the Fed, you could get that. So, if you think about using all of these things together, you could accomplish a great deal.

If we discovered that space aliens were planning to attack and we needed a massive buildup to counter the space alien threat and really inflation and budget deficits took secondary place to that, this slump would be over in 18 months. And then if we discovered, oops, we made a mistake, there aren't any aliens, we'd be better -

Ken Rogoff: And we need Orson Welles, is what you're saying.

Paul Krugman: No, there was a Twilight Zone episode like this in which scientists fake an alien threat in order to achieve world peace. Well, this time...we need it in order to get some fiscal stimulus.