It's to the best of our knowledge. I'm Anne Strange Champs. Today, across the universe.

One thing we love to do on this show is talk about big ideas, and there's no bigger idea, literally, than the universe.

Today we travel across time and space, wonder what it would be like to walk on Mars

and reflect on an unforgettable childhood visit to a planetarium.

I was born in the Bronx, New York,

where I pretty much thought I'd seen all the stars visible.

It was about 11 stars at night.

And here were thousands.

And in fact, I thought it was a hoax at first.

I would later recognize that, of course, that was the real sky. And in fact, I thought it was a hoax at first. I would later recognize that, of course,

that was the real sky. And I was struck, star-struck, really, by it.

But first, there is actually one thing that could be bigger than the universe, and that's the

multiverse. Theoretical physicist Max Tegmark is one of the leading proponents of the idea that we

could be living in just one of many universes. Steve Paulson caught up with him recently to talk

about his new book, Our Mathematical Universe. Max, you have a rather audacious theory that

reality is ultimately a mathematical structure, not just that math

describes our universe, but that our universe is made out of math, that it's a giant mathematical

object. Can you explain what you mean?

Yeah, this sounds kind of crazy. We look around ourselves in the world, and it doesn't

look particularly mathematical at all. But yet we physicists have, of course,

discovered that everything in our universe is made of these elementary particles like quarks and

electrons. And if you ask what properties does an electron actually have? You know, my friend Anthony's

...