Politicians like to talk about "American exceptionalism."
Let's expand the scope a bit and talk about Earth exceptionalism; that's what British scientist David Waltham writes of in his book Lucky Planet.
Waltham is both a biologist and a geophysicist, and he says the conditions that produced life on our planet may indeed be rare.
As in, not likely to be duplicated in our corner of the universe.
He joins us to make the case for Earth being a lonely planet in the cosmos.
