There's no shortage of voices sounding the alarm about the national debt.

Our fiscal situation is a 350-pound, two-pack-a-day smoker on the ICU table.

The U.S. federal budget is on an unsustainable path.

We're going to be broke really quickly unless we get serious about dealing with our spending issues.

I do believe that fiscal policy needs to be put on a sustainable course.

The U.S.'s borrowing levels are currently the same size as the entire economy and are expected

to skyrocket from here. That's because America spends

way more than it brings in and then borrows to cover that deficit. And there's plenty of

debate on how to close that gap, raise taxes, cuts spending, a combination of both. No doubt,

any solution demands hard choices. But what are the actual consequences if the deficit gets out of control?

I often liken this to the invisible dog fence where you really don't want to hit it,

but you won't know until you do. And it seems like the U.S. is almost intent on finding out where that tipping point is.

That's Maya McGinnis of the committee for a responsible federal budget.

Business leaders, politicians, economists, investors, almost all share a common fear that the U.S.

is playing with fire when it comes to its deficit, but less clear what the actual ramifications

look like if we reach that tipping point. This is CNBC's goal here, to explore not how to

fix the deficit, but rather what happens if we don't. Over the course of five months, we interviewed

a dozen people for the project and even more off the record. We surveyed everyone from former

Treasury Secretary Robert Rubin to PIMCO, CIO, Dan Iveson,

to former chairman of the Joint Chiefs of Staff Michael Mullen about what they think will happen

if the deficit gets out of control.

We dug into the empirical research in the history of how we got here.

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