When is a radio show about science and philosophy more than just a radio show about science and philosophy? When it's

Radiolab. Because hosts Jad Abumrad and Robert Krulwich are more than just two smart guys with microphones. Their radio show (and podcasts) sonically engage the listener with every word and every sound effect, weaving a heart-wrenching stories out of what, on paper, may look like incomprehensible research and dry facts. Add their witty banter, compelling soundscapes and revelations about the human mind, and you've got a guaranteed recipe for becoming so enthralled you completely miss your subway stop. If Congress needs a reason to keep giving NPR their funding, this is it.

Recently, the duo have taken their latest show, "Symmetry," on the road, recording and performing live across the country. In between their travels they took a moment to talk to us about where they get their ideas, how to improv on radio, why they hope the "nerd herd pillages and plunders the cultural landscape like a mongolian horde," and why their groupies don't even know what they look like.

We're sure you guys get this one all the time, but where do your ideas come from? And how do you find these people?

Jad Abumrad: We read a lot. We make lots of phones calls. We send each other a million articles with the subject line "interesting?" And we ultimately chase a lot of stories that never amount to anything. The storyverse is filled with almosts. It's getting to the point these days where we have to run at eight stories to get three. And that ratio will probably go up. So we spend a long time looking, and there's lots of murder involved (of story ideas, that is!). But at this point all of us share a gut. When something has that poetic spookiness, we all know it.

Robert Krulwich: I read a lot. And I look for themes. It's one of my recreations. Jad does it differently. He hunts for glorious tales. I sometimes send in memos saying, "Here's a topic with 10 different ways to go." We circulate, annotate it, add things, scratch off things. Often the idea that first caught my attention, that launched the notion, quietly disappears as we build the show, but the key question is: does this idea spawn baby ideas? If a theme keeps growing and growing, it moves to the head of the line. If it sits there, a single story, taking its own bows but not generating collateral ideas...it waits.

As for the people, they just show up. All different kinds, shy people, talkative people, exacting people, sloppy people, they are like musical instruments. When you investigate a story, they are out there, waiting. The trick is not to select for one kind of person, the great talker, the happy, noisy, celebrator. We like them in every possible flavor.

We have a few friends who worry that you're veering away from the "harder science" subjects. Is that something that concerns you?

JA: No. Your friends can get the hard science anywhere. And science explainers have never been the point of this show. If anything, Radiolab is a wrestling match between science and mystery. And speaking personally—Robert and I disagree on this point—I have no allegiance to physicists or biologists or neuroscientists. I root for mystery. What pulls me through the intensely long hours of producing this show is the chance to stand in awe of the world around me. But the key—and this is where the science comes in—that awe can't be a cheap awe. I want the awe that's hard fought, that you only get after interviewing impenetrable researchers and fighting with them a little. The point for me is to look past the scientists, to walk through the land of What We Can Know until you get to The Edge (I'm also a U2 fan).

RK: I happen to love the "harder science" subjects. I think that's where we make our greatest contributions. But Jad pulls hard to make sure that the emotional qualities of the tale, the hearts broken, the mystery addressed, the sweat generated, the cry of the unknown, the thrill of discovery, the ferocious egos, the gladiatorial science, that all that gets fully described. And the truth is, I agree with him. These are hard subjects, and one way to make them easier to listen to is to talk, not to the head, but to the heart. Every good storyteller knows that. Still, I love it when we pierce through a hard technical question. It makes me dance.

It's safe to say that one of the reasons people are drawn to your show is your banter with each other. You have a great way of playing off each other's attitudes and tones, which makes for great radio. And great theater, as many saw at the "Symmetry" performance at NYU. How much of that is scripted, and how much do you find yourself improvising? Is there even that much room for improvisation on radio?

JA: The ratio of scripted to made-up-on-the-spot is hard to pin down. But we figured out a while ago that the show finds it's groove when the two are somehow in an uncomfortable tension, where the anarchy and the architecture are kinda fighting to a draw. I sometimes think of the show as a musical version of a conversation Robert and I used to have at this one particular diner on 66th and Broadway, so like any conversation, the rhythms have to be freewheeling and unknown to us in the moment. On the other hand, when you're talking about the micro-evolution of a tumor cell, there's serious technical writing involved and that can't be improvised. So often what we'll do is improvise a lot—reams of blather—then isolate the best bits and script around them.

RK: This is where it feels to me like music, like we're a pair of instruments, riffing. Almost from the beginning, we could do this. It's not like ordinary conversation, or even ordinary radio conversation; it's always been a duet. So we do a take, then do another, then combine them into an edit, then listen, then feel—again, in a musical way—where it's not right, not making its points clearly, and we do it again. At first I thought this was the craziest, most uneconomical way to do a radio show I'd ever heard of. Now I'm kind of into it. In the end, what you get is a carefully edited, multiple takes version of a conversation that watches its details, hits its marks and sounds like two people having fun—which, most of the time, we are.

Do you guys prefer hosting the show in front of a live audience, or from inside a recording room? The two must be extremely different. Do you find yourselves preparing for a show differently if you're doing it live?

JA: I'm sorta liking the stage thing these days. I feel like some kind of adventure tourist up there. I'm not one of those natural performers, so it all feels new to me—the way you can slip from absolute terror in to this strange 900 person shamanic trance, and then back poof... throughout the course of a performance. But there are all kinds of things you can do on the radio that you obviously can't do live, by virtue of the fact that we're invisible on the radio. You can bleed the edges between the forms. An interview can magically morph into surreal bit of radio theater. Two people talking can suddenly become three, as if the third person just suddenly barged in through a wall that wasn't there. A person's words can stretch like toffee to become something like wind. The mental stage of a radio moment is fluid. It constantly shifts and changes. The actual stage of a live performance is, well, not that way.

RK: Oh, it's kind of amazing to suddenly glance out at all those people. Plus, Jad sitting there, strumming his computer and making these sounds, Aladdin-like, emerge from his machine—that's good too. But I guess my heart is in the deeply imaginative space that allows us to strip an idea and build it back up again, note by note, phrase by phrase, till it bends to our will. We are doing some very, very advanced technical writing in these shows and we are inventing new ways to do it. And that's where the deep challenge was and still is.

What led you to radio, and what about the format of radio do you think makes the show work? Do you think it would be the same if you put yourselves on TV or on a YouTube channel?

JA: We've gotten a lot of interest in making a TV version of Radiolab, but every time, when we get down to the pertinent questions—What would it look like? What would it feel like?—everyone draws a blank. I'm sure there's some pill-popping animator out there who could prove me wrong. But right now, even though we experiment a lot with short videos (in fact, we're about to release one on our podcast), I'm most comfortable when there are no pictures involved. Radio works for us simply because it's such a visceral media. The sound actually slams into your ear drum. It's physical. And because it hits your ear only, if I do my job right, you're forced to join me in co-authoring the pictures into being. There's something fundamentally more empathic about the whole experience. We're doing it together.

RK: I have never stopped thinking in pictures. I spent 23 years in commercial TV—plus public TV—so pictures and I have a long history together. I have pushed the Radiolab team to think about video podcasts and the ones we've done, with Everynone (a Brooklyn-based group) and more recently, (with help from NPR), with Benjamin Arthur, are deeply beautiful and challenging, just like the radio show. I can't imagine a future for Radiolab, or for any serious storytelling outfit, that doesn't include a deep exploration of what you can do for a pair of eyes. Ears we're good at. Eyes matter too. People, for whatever reason, will mail each other things they just saw more quickly than they will e-mail things they just heard. Also, the machines we carry will probably make it more and more possible to bounce from sound to sight with a tap or a nod or a who-knows-what, so the border between sight and sound is narrowing all the time. I don't know about a TV show, (in the classic 58 minute sense), but I am all for visuals: drawings, designs, infographics, animations, videos—this is just another way to explore.

A few years ago the stuff you cover may have been considered "nerdy." But given how popular you are, clearly the nerds aren't in the minority anymore. How do you feel about "nerd culture" being in the spotlight?

JA: I hope the nerd herd pillages and plunders the cultural landscape like a mongolian horde. That said, what exactly counts as a nerd these days? I'm pretty sure I'm a nerd and everyone I know and care about is a nerd, but how does one know?

RK: Turns out, everybody has a little nerdy goblin inside. Joe Sixpack has his nerdy moments. Albert Einstein had his Sixpack side (ever see that crazy tongue picture?) I don't think about these distinctions much.

What are some of your favorite Radiolab segments?

JA: My recent favorite is the Words episode. In that show, one of the central questions was, can a person think without words? Do words merely describe thought, or do words actually create thought? I like thinking about that while watching my son learn his first words.

RK: I was really happy about The Good Show, which wondered out loud why people and animals are sometimes willing to be kind and generous. We attacked the subject—talk about dangerous—as a mathematical problem, which is how biologists think about it. I found doing that show totally fascinating, and very, very hard. We had to invent all kinds of sounds and tropes to make the math clear; we had to interview a bunch of different people, had to stretch, had to revise endlessly, had to reach well past anyone's idea of how long it should take to do a story, but in the end we gave our audience something hard to think about that bubbled along like a stream. That's what I love.

When you're not doing Radiolab, what are you favorite things to do around the city?

JA: Every time we hit a big deadline, I'll take the day off and walk from Brooklyn, over the bridge, all the way to Harlem and then back. I get to do that twice a year and it makes me very happy.

RK: I am always walking. I wander. I get stopped by places that I didn't know are hiding in plain sight—like the Wave Hill gardens over the Hudson, or the Locust Trees that sit in a clump in Fort Tryon Park that in spring time are the choice make-out center for high school students, but if I sit really quietly, they ignore me. I like discovering a 50 nest high "apartment building" of sparrow nests tucked between two buildings on 106th and Riverside. I like sitting along the canal that separates Staten Island from New Jersey and watch the giant Asian ships loom over me as they roll by. New York is the perfect leveler. If you feel like you are a superstar, you can dash out onto the street and discover that nobody cares. If you are feeling awful, and ugly and sad, you can drift onto the street, and people pay you the privilege of not noticing. I was born here. I love it here.

Silly, but do you guys have groupies?

JA: I saw someone the other day carrying a radiolab tote. She had no idea who I was. Does that count?

RK: If I do, they are very, very shy.