Ah, Benny's parents, thanks for coming.

Hiya.

So, Benny has really blossomed this term.

You're telling me, he outgrew his bike. We sold it, on eBay.

Oh, that's not quite what I meant.

It's free to sell on there?

Free to sell?

Easy too. Sold Benny's bike, your guitar, my jacket.

You sold my guitar?

Shall we talk about Benning?

When it's this easy to sell for free, you can't help but say when it's eBay.

Things people love. T's and Cs apply, exclusive vehicles.

Welcome to Scientific American Science Talk posted on May 6th, 2015.

I'm Steve Merski.

On this episode, along with some historians, I think that a great deal of history is actually contingent, and given slightly different circumstances or different

luck, key world events could actually have gone in a completely different direction. That's Alan Smale,

he's an astronomer, and he's also the author of a new novel called Clash of Eagles.

It takes place in the 13th century AD in a world where the Roman Empire never fell,

and in which a Roman legion has made it across the Atlantic to North America.

We talked by phone about the book and the field of alternate history writing in general.

Stay tuned after our conversation for some

brand new research about some of the people in his book. First, tell us about your day job. You're

...