Hello, I'm Chad Haboomrod.

And I'm Robert Crulwich.

And this is Radio Lab, the podcast.

Which means it's not Radio Lab, the beautiful show that we do here. No, this is a shorty. In this podcast, we're going to take you to New York City to the 92nd Street Y, where I do a series called Giants of Science. And on one night, something very cool happened. Was I in the audience of that? I thought you were. I thought I saw you there in Road 3.

I can't. I can't remember about it. Anyhow, tell him, tell us. I'll shut up. The guest is, well, I don't have to. Let's just go to the hall, and Robert, on tape, we'll take over from here. The man you are about to meet is he's a professor at Columbia University of Mathematics.

He's also a professor of physics at Columbia University. He's also the director of the Institute for Strings, Cosmology, and Astroparticle Physics at Columbia University.

He's also a best-selling author. He's also done work in what's called mirror symmetry, which means I'm not sure what exactly. It involves over relating two different Kalabiyao manifolds, relating the conifold to one of the orbifold, which I'm sure you know all about. He's a Rhodes Scholar. He's the author of the elegant universe. So basically he's not a dumb person, not at all, but... He does, however, believe the most peculiar things. So if you ask

him, and I will, he believes that if you travel from this room, from this auditorium on

90 Second Street and Lexington Avenue in pretty much any direction at all, but if you have

to go really, really, really far, light years upon light years, upon light years out, you will, if you travel far enough, eventually find a galaxy, but that looks, and I mean exactly like our Milky Way. And in that galaxy, you will find a planet that is an absolute copy, a dead ringer for our planet Earth.

And on that planet, you will find a city that is uncannily down to the hairs on the city

rats exactly like this city, New York City.

And in that city, there will be another 90-second street, YW-Y-M-H-A, with a building that

has another auditorium in it that is exactly like this auditorium

here. And if you think that's an unlikely coincidence, I'm just getting started because I think

Brian Ging will also tell you that in that distant, distant auditorium on the other side

of the cosmos backstage waiting to come on stage, there is another professor who also teaches both mathematics and physics

at a school that just happens to also be called Columbia University, who's also the director of Institute for Strings, Cosmology, and astroparticle physics,

who also just happens to be named Brian Green with an E on the end, like this one, the one out here, who happens to have an

identical set of also two sisters and the same mother and the same father with the same

memories down to what he ate this morning for breakfast, which would not be an egg, because

the far away, Brian Green, like the nearby Brian Green, are both of them vagans. And we're

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