Oh Knuck-Crackers! The Science of Poppin' Knuckles : Wow in the World It's finger poppin' time on Wow in the World, and this week, Mindy and Guy explore the science behind the SNAP, CRACKLE, AND POP of our knuckles! Where in the world is that sound coming from?! Why in the world does it make some people so uncomfortable? And how in the world is it even made? Join in on an interesting quest for the latest Who, What, When, Where, Why, How, and Wow in the World of KNUCKLE CRACKING!
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Oh Knuck-Crackers! The Science of Poppin' Knuckles

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Oh Knuck-Crackers! The Science of Poppin' Knuckles

Oh Knuck-Crackers! The Science of Poppin' Knuckles

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  • <iframe src="https://www.npr.org/player/embed/620464748/620470841" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

(SOUNDBITE OF SONG, "THE GOLDEN AGE (WOW IN THE WORLD PODCAST THEME SONG)")

UNIDENTIFIED PERSON #1: Stay seated. Three, two, one, ignition.

UNIDENTIFIED PERSON #2: Get ready for an adventure of magnificent proportion.

THE POP UPS: (Singing) I don't know what you've been told, but we're in a golden age - so many discoveries that are jumping off the page. Wow in the world. Wow in the world. Wow in the world. Wow in the world. Wow in the world. Wow in the world. Wow in the world. Wow in the world. Wow in the world.

UNIDENTIFIED PERSON #3: With Guy and Mindy.

UNIDENTIFIED PERSON #1: We're on our way, Houston.

UNIDENTIFIED PERSON #4: Breathe deeply in and out. Now float away upon that breath - up, up, up - gently twirling amongst the moon beams. Oh, look. The moon waves to you knowingly like an old neighbor. Wave back now. Hello, moon. Hello.

(SOUNDBITE OF ALARM)

MINDY THOMAS, HOST:

I'm up. I'm awake. Hop out of bed. Run to the bathroom. Brush my teeth. (Vocalizing). Time to get dressed. Call my buddy Guy Raz to make sure he's awake. Dial, dial, dial, dial, dial.

GUY RAZ, HOST:

Hello?

THOMAS: Good morning, Guy Raz.

RAZ: Mindy, it's the middle of the night.

THOMAS: You call it the middle of the night. I call it 3 o'clock in the morning. And you know what day it is.

RAZ: I don't know. Is it your birthday?

THOMAS: Nope.

RAZ: Is it my birthday?

THOMAS: Nope.

RAZ: Oh, no. Is it Reggie's taekwondo and tapdancing recital? Is that today.

THOMAS: What? No. That's not even until next month. By the way, I signed you up to be the stage mom.

RAZ: But I'm not even...

THOMAS: Guy Raz, today is thumb wars day at the Knuckle Hut (ph). Guy Raz? You there? Did I lose you?

RAZ: (Groaning).

THOMAS: What?

RAZ: Mindy, I'm going back to bed.

THOMAS: What? No. There's no time. We need to get there early if we want good seats. Grandma G-Force is competing.

RAZ: Wait. Grandma G-Force is a professional thumb wrestler?

THOMAS: Among other things, yes.

RAZ: Well, I guess I got to see this. What time are we leaving, Mindy?

THOMAS: Well, I'm ready now.

RAZ: Of course you are. All right. Well, I still need to brush my teeth, do my calisthenics routine, the Five Tibetans, the juice cleanse, my morning meditation. I've got to get dressed.

THOMAS: Wait. Don't get dressed.

RAZ: What?

THOMAS: I've got something perfect picked out for you to wear.

RAZ: Mindy, I'm not...

THOMAS: Be right over.

(SOUNDBITE OF DOORBELL)

RAZ: I'm coming. I'm coming.

THOMAS: Ta-da.

RAZ: What are you wearing?

THOMAS: I made us thumb war costumes out of foam.

RAZ: You're dressed as a giant foam hand?

THOMAS: Well, a giant foam right hand. You're going to be the giant foam left hand. Here.

RAZ: Oh, no. No, no. No way. I am not...

THOMAS: Now let me just pull it over your head here.

RAZ: Mindy...

THOMAS: Hold your breath. Would you stop wiggling so much? Stay still. I'm going to - here we go. There. Don't you look cute?

RAZ: (Groaning) Where's my full-length mirror? Mindy, I have no peripheral vision in this thing.

THOMAS: Be careful when you turn around and walk. You might...

(SOUNDBITE OF CRASH)

THOMAS: ...Knock everything over.

RAZ: Oh, hey. You know, Mindy, now that I see myself in the mirror, I don't look half bad.

THOMAS: Guy Raz, you look like a high five.

RAZ: (Screaming). Did you see just body slam me? What was that for?

THOMAS: I gave you a full-body, hand-suit-to-hand-suit high five.

RAZ: Why do I feel like this is going to be the longest day of my life?

THOMAS: Oh, well, probably because it's going to be the longest day of your life.

RAZ: Oh, right. Starting at 3 am.

THOMAS: Well, ready to go?

RAZ: Nope.

THOMAS: (Yelling) Reggie.

RAZ: Reggie, did you swoop in here wearing a sleeping mask?

THOMAS: Oh, no. He's been doing that a lot lately.

RAZ: Doing what?

THOMAS: Sleep sailing through the air.

RAZ: Is that safe?

THOMAS: Yes, of course it's not safe, Guy Raz. Now just gently tickle him awake, OK?

RAZ: Wake up, Reggie. Early bird gets the worm.

THOMAS: Good morning, Reg. We need you to give us a quick ride to the Knuckle Hut.

(SOUNDBITE OF BIRD COOING)

THOMAS: Yes, you can make a pit stop at the Seed Shack once you drop us off.

(SOUNDBITE OF BIRD COOING)

THOMAS: What on earth are we wearing? Oh, these are just giant foam hand suits that I made for us. I made them for Grandma G-Force's thumb war today.

(SOUNDBITE OF BIRD COOING)

THOMAS: High five?

(SOUNDBITE OF BIRD COOING)

RAZ: Oh, no.

THOMAS: Sure. Guy Raz loves a good high-five.

RAZ: (Screaming).

THOMAS: Wow, Guy Raz. You must be as light as a feather.

RAZ: He just knocked me over with his talon.

(SOUNDBITE OF BIRD COOING)

THOMAS: Oh, Reggie says high five.

RAZ: Let's just go, Mindy.

THOMAS: After you. Hey, Guy Raz, give me a boost, and then I'll turn around and pull you up. It's hard to move in this giant foam hand suit.

RAZ: OK.

THOMAS: Thanks, buddy. OK. Your turn. OK. All set?

RAZ: No.

THOMAS: Did you say go?

RAZ: No.

THOMAS: Okeydoke (ph). Here we...

RAZ: No.

THOMAS: ...Go.

(SOUNDBITE OF MUSIC)

THOMAS: Thanks, Reg. You want to stick around?

(SOUNDBITE OF BIRD COOING)

THOMAS: Oh, early bird special at the Seed Shack. OK. Just head back over here when you're finished.

(SOUNDBITE OF BIRD COOING)

RAZ: Wait. The Knuckle Hut is a diner?

THOMAS: Yeah. It's been here since the 1950s.

RAZ: And what's that creepy hand statue coming out of the ground?

THOMAS: Oh, so that's a giant sculpture modeled after the left hand of the original owner, Thomas Fingerling (ph). In fact, it's an exact replica - insides and all. Some say that when he cracked his knuckles, you could hear it from 40 miles away.

RAZ: Yeesh.

THOMAS: Want to go inside?

RAZ: The diner? Yeah, I'm starving. I wonder if they've got some fermented mung beans.

THOMAS: We'll get to the diner later. First, I think we need to find out what's going on inside that hand.

RAZ: You want to go inside that giant hand dressed like giant hands?

THOMAS: Yes.

RAZ: But don't you want to at least say hi to your Grandma G-Force first?

THOMAS: No.

RAZ: But she's your grandma.

THOMAS: Guy Raz, Grandma G-Force isn't even going to get here until 14 hours from now. The thumb war starts at, like, 8 p.m.

RAZ: Mindy, you dragged me here at 3 a.m.?

THOMAS: Follow me, Guy Raz. Waddle, waddle, waddle, waddle, waddle, waddle, waddle, waddle.

RAZ: Waddle, waddle, waddle, waddle, waddle, waddle, waddle, waddle.

THOMAS: Is it just you, Guy Raz, or am I sweating?

RAZ: You know, you'd think foam would be a little more breathable than this.

THOMAS: OK. Brace yourself, Guy Raz, because I'm going to open the door on this giant, creepy hand.

(SOUNDBITE OF OPENING DOOR)

THOMAS: Hello? Anyone in this hand?

RAZ: Mindy, why is it so dark inside here? Wait. Are those real bones?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Twenty-seven bones, to be exact.

RAZ: What? Who said that?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) My name, young lady, is Thomas Fingerling. Welcome to my hand.

RAZ: You're still alive?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) More or less. I see you two are dressed in the traditional hand suit. Ooh. Is this some sort of high-density, open-cell polyurethane?

THOMAS: Thank you for noticing. Made them myself. See, my name is Mindy. And this here is my little buddy Guy Raz. And we came out this way to see my Grandma G-Force compete in the Knuckle Hut's annual thumb war. But then...

RAZ: But then we couldn't help but notice this giant hand replica sculpture thingy. And we thought we'd stop in to check it out.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Well, that's right curious of you. I don't get too many visitors around these days - not since the invention of the Internet superhighway.

THOMAS: (Groaning) The Interwebs. Am I right?

RAZ: Wait. What?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Long ago, knuckle-cracking enthusiasts from around the globe would come to witness my signature Popping Knuckchuck (ph) performance.

THOMAS: Your what?

RAZ: (Whispering) He said his signature Popping Knuckchuck...

THOMAS: (Whispering) I heard what he said, Guy Raz.

So, Thomas Fingerling, what happened exactly?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Well, like I said, once the Internet came along with their WWWs and their Netscape Navigators, people moved on to other forms of so-called entertainment.

RAZ: You're saying that people used to come here to watch you crack your knuckles for entertainment?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Don't sass me, young lady. And yes. But all these Yahoos and dot-com bubbles came along and took my audience. Now it's all MewTube (ph) videos of cats in hamburger buns or what have you.

THOMAS: Oh, yeah. Did you see the one where the cat was wearing a little blueberry pancake beret and rollerskating past the Eiffel Tower in Paris? You got to see this. Here. I'll pull it up on my phone. You are not going to believe this. It is so cute.

RAZ: So let me get this straight. What you're saying, Mr. Fingerling, is that knuckle cracking isn't drawing the same crowds that it was back in the 1950s?

THOMAS: Yeah. So no one is super-impressed by knuckle cracking anymore?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) I'm afraid not, young lady.

THOMAS: Hey, who you calling a lady?

RAZ: Well, Mr. Fingerling, we're here now. Maybe you can show us around your giant hand replica, and we can talk knuckles for a while.

THOMAS: Yeah. That's a great idea. And maybe for the grand finale, you can perform your signature Popping Knuckchuck for us?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Well, I suppose I still got a little pop left in the old knucks.

RAZ: That would be amazing. Woo-hoo.

THOMAS: Yay. This is going to be awesome.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Let's see here. We got tickets to the tour, plus the IMAX video, a refillable sippy cup and the Knuckchuck performance. That'll be $75.92. Oh, hey - 92. That's my age.

RAZ: I'm sorry. Did you say...

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Ninety-two years young, by gum.

RAZ: No, I mean the price of tickets. Seventy-five...

THOMAS: I got this, Guy Raz.

RAZ: Hey, where'd you get my wallet?

THOMAS: Just a little sleight-of-hand trick I've been working on. Twenty, 40, 60, 75 dollars. Here you go, Thomas Fingerling. Two tickets, please.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Thank you for your business. And, well, gosh, I'm just so happy. No one's stopped by here in over 30 years. Between you and me, people tend to find this place a little bit creepy.

RAZ: So where do we begin?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Oh, I suppose wherever you want. Feel free to have a look around. I'll just be napping up in the thumb over there.

RAZ: Napping? What about the tour?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Gadzooks. What do you think this is, a haberdashery? It's self-guided. Now you two kids have fun.

RAZ: Self-guided? Seventy-five bucks?

THOMAS: Don't worry, Guy Raz. I got this.

RAZ: The last time you said that, you stole my wallet, Mindy.

THOMAS: No, really. Half the reason I even wanted to visit the inside of this weird hand sculpture anyway is because I just read this new research on knuckles. And I wanted to get a close-up experience of what it's like when we crack them.

RAZ: You dragged me all the way out here for...

THOMAS: So to begin the tour, Guy Raz, I'd like for you to pull my finger.

RAZ: Oh, no.

THOMAS: Pull my finger, Guy Raz.

RAZ: Nope.

THOMAS: Pull it.

RAZ: (Groaning) Fine.

(SOUNDBITE OF FART)

THOMAS: Whoops.

RAZ: Mindy...

THOMAS: Sorry. Wrong finger. Here, try this one.

RAZ: Mindy, I'm not...

THOMAS: OK. I'll do it. Watch and learn.

(SOUNDBITE OF CRACKING KNUCKLE)

RAZ: Did you snap it off, Mindy?

THOMAS: Nope. That was the sound of me cracking my knuckle. Here, want me to do it again?

RAZ: No, I...

THOMAS: OK.

(SOUNDBITE OF POPPING CORK)

RAZ: Mindy, I'm not sure it's supposed to sound like that.

THOMAS: So you might be wondering to yourself, Mindy, what makes our knuckles crack like that?

RAZ: (Groaning) Mindy, what makes our knuckles crack like that?

THOMAS: Walk with me, Guy Raz, as we climb that super-tall ladder over there to the pointer finger. And there we will find the answer.

RAZ: Are you sure that ladder is safe to climb?

THOMAS: Yes, of course I'm not sure it's safe to climb, Guy Raz. You go first. Climb, climb, climb, climb, climb, climb. climb.

RAZ: Whoa.

THOMAS: Whoa.

RAZ: Look at that, Mindy. Look where the bones of the finger meet the rest of the hand.

THOMAS: That's the knuckle.

RAZ: And there's a little lake inside of it.

THOMAS: Oh, yeah. That's the lake of synovial fluid. Want to take a dip?

RAZ: I don't think that's a good idea, Mindy. There's a sign here that says this lake is full of gas.

THOMAS: Yep. This lake of synovial fluid is full of tiny gas bubbles mostly made up of carbon dioxide.

RAZ: But what's the purpose of the fluid in the first place?

THOMAS: Well, why don't you press that button over there and see what happens?

RAZ: I don't know.

THOMAS: Guy Raz, the sign says press me and see what happens.

RAZ: OK.

Whoa. Whoa. The finger is moving, Mindy, and we're moving with it.

THOMAS: Guy Raz, check it out. The synovial lake of fluid is keeping the finger bones from grinding on each other.

RAZ: Wow.

THOMAS: Now let's see what this lever does.

RAZ: Mindy, the finger bones are pulling away from each other. Stop cranking. Stop cranking.

THOMAS: OK. Now watch that pressure gauge to your right.

RAZ: It appears that when the bones pull away from each other, there's a second drop in pressure in the middle of the knuckle or joint.

THOMAS: Yeah. And look. With the pressure drop, the gases are coming together and making new bubbles.

RAZ: Mindy, Mindy, could the popping of these bubbles be what's causing the popping sound in our knuckles?

THOMAS: Well, that's what some scientists thought for a long time.

RAZ: But?

THOMAS: But other scientists were like, no dice. Clearly, the pop comes from the way the bubbles are formed. And then they went back and forth on this for, like, a hundred years.

RAZ: And, you know, Mindy, I once read that some of the earliest research on knuckle cracking, dating back to the 1900s, showed that not all joints were crackable.

THOMAS: Oh, yeah. And that once you pop, you can't stop - until you wait for at least 20 minutes first.

RAZ: You can't pop the same knuckle more than once in a 20-minute period?

THOMAS: See for yourself.

(SOUNDBITE OF CRACKING KNUCKLE)

RAZ: Huh.

THOMAS: See what I mean?

RAZ: So, Mindy, earlier you'd mentioned some new research on knuckle cracking.

THOMAS: Oh, yeah. So this pair of researchers from the Ecole Polytechnique in France - they made a mathematical model to find out the truth of what's been causing the pop.

RAZ: A mathematical model?

THOMAS: Yeah. So basically, they made this math video game that simulated what happens when our knuckles crack.

RAZ: A mathematical video game? That's my kind of video game.

THOMAS: And in this video game, they had a model of an knuckle with a bubble in it. And then they cracked it over and over and over and over again, listening carefully to the sound it made and how loud that sound was.

RAZ: And then I'm guessing they compared that sound with the sound of actual people cracking their knuckles.

THOMAS: You got it. They compared the sounds in this mathematical video game knuckle with the sounds of their own knuckles and the knuckles of a bunch of volunteers.

RAZ: That must have sounded like a knuckle-popping party.

(SOUNDBITE OF CRACKING KNUCKLES)

THOMAS: That's the way I imagine it. And if I'm wrong, I don't want to be right.

RAZ: So what did they find?

THOMAS: Well, what they found is that when they popped the bubbles on the video game, the bubbles made pretty much the same sounds as the popping knuckles make in real life.

RAZ: So it is the popping of the bubbles after all.

THOMAS: Well, not so fast. See, they also found that when the bubbles only started to collapse - like, less than halfway not popped completely - they still made the same sounds.

RAZ: So what does that mean?

THOMAS: So what this means is that the popping could have something to do with the way the bubbles are formed after all.

RAZ: So I guess it's back to the Knuckle Hut for these researchers.

THOMAS: Speaking of Knuckle Hut, it's probably about time for Grandma G-Force's thumb war to begin.

RAZ: I thought that wasn't for another 14 hours or so.

THOMAS: Guess time flies when you're popping these guys.

(SOUNDBITE OF CRACKING KNUCKLES)

RAZ: Mindy, stop. You're going to give yourself arthritis.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Fake news.

RAZ: What? Who said that?

THOMAS: Guy Raz, Thomas Fingerling is right.

RAZ: Huh?

THOMAS: Arthritis is a disease that keeps people's joints from working in the way they're supposed to. And people with arthritis in their hands can have swelling, pain or stiffness in their joints or knuckles.

RAZ: Yes. But?

THOMAS: But no studies have been able to show any connections between arthritis and knuckle cracking.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Which means it's finger-popping time.

RAZ: It's what?

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Let's head up to the thumb war at the Knuckle Hut. I've been preparing a grand finale you'll never forget.

THOMAS: Your signature Popping Knuckchuck.

RAZ: Oh, boy.

THOMAS: After you, Mr. Fingerling.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Why, thank you, kind sir.

THOMAS: Hey, who you calling sir?

RAZ: Just keep on moving, Mindy.

THOMAS: Calling me sir. I'm a lady.

(SOUNDBITE OF WHOOSH)

THOMAS: Whoa. This is thumb-believable.

RAZ: This is a diner. By the way, do you think we have time for me to order an einkorn and quinoa salad?

THOMAS: No time for that, Guy Raz. Look. Grandma G-Force and her competitor are already in the ring.

RAZ: Mindy, that's a corner booth in the diner. I'm going to go put our names in for that table once they're finished with this whole thumb war thing.

THOMAS: Grandma G-Force, hi. Hi, Grandma G-Force. It's me, Mindy, your granddaughter Mindy. Hi. Grandma G-Force, look over here. Over here, Grandma G-Force.

UNIDENTIFIED ACTOR #2: (As Grandma G-Force) I'm cracking knucks and taking names.

RAZ: I don't think she can hear you, Mindy. She looks like she's really in the zone. Say, where did thumb wrestling come from anyway?

THOMAS: Oh, glad you asked. As the legend would have it, it all started in the year 1936, when a young lad who went by the name Julian Koenig got bored one day at summer camp.

RAZ: And?

THOMAS: And that's it. That's the legend.

RAZ: Huh.

UNIDENTIFIED ACTOR #3: (As announcer) Our contestants for this round of thumb wars are Grandma G-Force and Thumberlina (ph) vs. Sir Alexander Curley (ph) and the Thumber Taker (ph).

RAZ: Wait. Why are there four contestants?

THOMAS: Oh, that's because the thumbs have their own wrestling names and faces and tiny hats.

RAZ: What?

UNIDENTIFIED ACTOR #3: (As announcer) The rules for this match are as follows. Number one, elbows must be on the table at all times. And number two, finger nails must be trimmed to tiny nubs.

GUY RAZ AND MINDY THOMAS: Yikes.

UNIDENTIFIED ACTOR #3: (As announcer) Sixty seconds are on the clock. It's time for the wild thumb war showdown to throw down.

UNIDENTIFIED ACTOR #2: (As Grandma G-Force) One, two, three, four, I declare a thumb war.

RAZ: Go, Grandma G-Force. Go, Thumberlina. You can do it.

THOMAS: Come on, Grandma G-Force. Make me proud. Show them what our genes are made of.

UNIDENTIFIED ACTOR #4: (As character) Oh, my thumb.

RAZ: I think she's got him, Mindy. Look.

UNIDENTIFIED ACTOR #2: (As Grandma G-Force) One, two, three, four. I nailed this thumb war.

UNIDENTIFIED ACTOR #4: (As character) I'm all thumped.

RAZ: Woo. Yeah. There's nothing you can't do, Grandma G-Force.

THOMAS: Grandma G-Force. Woo. Yes, yes, yes, yes, yes, yes.

UNIDENTIFIED ACTOR #2: (As Grandma G-Force) Now who wants to pull my finger?

(SOUNDBITE OF FART)

THOMAS: Runs in the family.

UNIDENTIFIED ACTOR #3: (As announcer) Grandma G-Force and Thumberlina have won in a thumb-believable upset.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Hoo. Ha. Hoo. Pop, pop, pop, pop.

RAZ: What's that, Mindy?

THOMAS: Is that what I think it is?

RAZ: Look up there on the bar. It's Thomas Fingerling.

THOMAS: Thomas Fingerling?

(SOUNDBITE OF KNUCKLES CRACKING)

THOMAS: Wow. Talk about a grand finale. Just listen to him crack those knucks.

RAZ: Thumbs-up, Mr. Fingerling. You still got it in you.

UNIDENTIFIED ACTOR #1: (As Thomas Fingerling) Pop, pop, pop, pop, pop, pop.

UNIDENTIFIED CHILD #1: WOW IN THE WORLD will be right back. Grown-ups, this message is for you.

(SOUNDBITE OF MUSIC)

UNIDENTIFIED CHILD #1: That's it. Back to the show.

(SOUNDBITE OF SONG, "THE GOLDEN AGE (WOW IN THE WORLD PODCAST THEME SONG)")

THE POP UPS: (Singing) Wow in the world.

(SOUNDBITE OF DIALING PHONE)

THOMAS: Hi. Thanks for calling WOW IN THE WORLD. After the beep, get ready to record.

(SOUNDBITE OF BEEP)

HANNAH: Hi, Mindy, Guy Raz and Reggie. My name is Hannah (ph). I'm 11 years old, and I'm from Raleigh, N.C. My wow in the world is that Uranus rotates unlike any other planet in our solar system. Scientists think that Uranus was hit by a meteor to tilt it over, and that's why Uranus rotates counter-clockwise like a wheel. I love your show. Bye.

(SOUNDBITE OF BEEP)

ALICE: My name's Alice (ph). And I'm 4 years old. And I am from Highland Park, N.J. And my wow in the world is that black holes can burp.

(SOUNDBITE OF BEEP)

ELIZA: Hi, Mindy and Guy Raz. My name's Eliza (ph), and I'm 5 years old. And I live in Hawaii. And my wow in the world is that you can see the eruption from the bigger (ph) island all the way from outer space. Aloha.

(SOUNDBITE OF BEEP)

EDIE: Hi. My name is Edie (ph), and I'm from Mountlake Terrace. And my wow in the world is that clouded leopards are the oldest cat species alive.

(SOUNDBITE OF BEEP)

MAYA: Hi, Mindy. Hi, Guy Raz. My name is Maya (ph). I'm 6 years old, and I live in Southern California. My wow in the world is that nitrogen gas is what makes the sky blue. I love your show. Have a (unintelligible) day. Bye.

(SOUNDBITE OF BEEP)

LEO: Hey, Mindy. Hey, Guy Raz. Hey, Reggie. I'm Leo (ph) from Salt Lake City, Utah. And my wow in the world is that scientists believe cats learned hissing from snakes. Love your show. Bye.

(SOUNDBITE OF BEEP)

EMILY: Hi. My name is Emily (ph). I'm from Austin, Texas. And I'm 6 years old. And my wow in the world is that the Ancient Egyptians thought that the brain wasn't important.

(SOUNDBITE OF BEEP)

BEN: Hi. My name is Ben (ph), and I live in New York City. And I am 6 years old. And my wow in the world is that the Sphinx was made out of one piece of limestone. Bye. I love your show. (Laughter).

(SOUNDBITE OF BEEP)

UNIDENTIFIED PERSON #5: End of messages.

THOMAS: Hey, everyone. Thank you so much for joining us this week on WOW IN THE WORLD.

RAZ: And if you want to keep the conversation going, check out some of the questions we've posted on this episode at our website wowintheworld.com.

THOMAS: And, grown-ups, there you can find more details on how your kids can become part of the World Organization of WOWZERS. Lots of cool perks - exclusive T-shirts, autographed pictures of us and a bunch of other cool stuff - wowintheworld.com.

RAZ: Our show is produced by Jed Anderson...

THOMAS: Say hello, Jed.

JED ANDERSON, BYLINE: Yello.

RAZ: ...With help from Thomas van Kalken, Chelsea Ursin and Jessica Boddy. Meredith Halpern-Ranzer is the big boss.

THOMAS: Our theme song was composed and performed by The Pop Ups. You can find more of their awesome, all-ages music at thepopups.com.

RAZ: And, parents and teachers, if you want to send us an email, our address is hello@wowintheworld.com.

THOMAS: Grown-ups, you can also find us on Facebook, Twitter, and Instagram at @wowintheworld.

RAZ: And if you want to be featured at the end of the show, call us up and tell us your wow in the world.

THOMAS: Our phone number is 1-888-7-WOW-WOW. That's 1-888-7-WOW-WOW.

RAZ: And, parents, if you want to upload any photos or videos or messages to us, please visit wowintheworld.com and find a link where you can do just that.

THOMAS: And if you haven't already done so, please subscribe on Apple Podcasts or however you get your podcasts. Leave us a few stars and a review and be sure to tell a friend about the show. Until next time, keep on wowing.

(SOUNDBITE OF SONG, "THE GOLDEN AGE (WOW IN THE WORLD PODCAST THEME SONG)")

THE POP UPS: (Singing) Wow in the world. Wow in the world. Wow in the world. Wow in the world. Wow in the world.

UNIDENTIFIED CHILD #2: WOW IN THE WORLD was made by Tinkercast and sent to you by NPR.

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