I'm Alan Alda, and this is clear and vivid conversations about connecting and communicating.

It turns out in the entire visible universe, there are 10 billion trillion habitable planets.

It's every one of those planets that's in the right place for life to form is like an

experiment that nature has run. And the only way that we're the only time in the entire

universe that life and intelligence has formed is if every one of

those experiments failed.

So you've had 10 billion trillion chances to form something else like us.

And if you think they all fail, then it's up to you as a pessimist to tell me why it could

have happened here on Earth, but then the other 10 billion trillion experiments

failed.

It doesn't mean that there's somebody for us to discover next week, but it just means that

the possibilities are so vast that it's unlikely that we're the only time that this has

ever happened.

That's Adam Frank.

An astrophysicist at the University of Rochester, he studies how stars form and how they die.

He's also a self-described evangelist of science.

When we discovered his book, The Little Book of Aliens, we realized he was the perfect person to follow last week's episode

in which we talked about the craze a little more than a century ago

around the idea that aliens were living on Mars.

This is an interesting time for us to be having this conversation.

We just had a conversation last week about how in the early 1900s, the New York Times announced that there was definite proof of life on Mars.

Oops.

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