Learn about why Christmas music sounds like Christmas; the Crocodile Paradox, an unsolvable dilemma that dates back to ancient Greece; what causes the smell of fresh rain; and why the National Science Foundation wants your idea for their next project. In this podcast, Cody Gough and Ashley Hamer discuss the following stories to help you get smarter and learn something new in just a few minutes: Here's Why Christmas Music Sounds Like Christmas The Crocodile Paradox Is an Unsolvable Dilemma That Dates Back to Ancient Greece Know that Fresh Rain Smell? Here's What Causes It The National Science Foundation Wants Your Idea for Their Next Project Follow Curiosity Daily on your favorite podcast app to learn something new every day withCody Gough andAshley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Learn about why Christmas music sounds like Christmas; the Crocodile Paradox, an unsolvable dilemma that dates back to ancient Greece; what causes the smell of fresh rain; and why the National Science Foundation wants your idea for their next project.
In this podcast, Cody Gough and Ashley Hamer discuss the following stories to help you get smarter and learn something new in just a few minutes:
Follow Curiosity Daily on your favorite podcast app to learn something new every day with Cody Gough and Ashley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Full episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/christmas-music-psychology-rain-smell-science-crocodile-paradox-and-pitching-the-nsf
[MUSIC PLAYING] CODY GOUGH: Hi. We've got the latest and greatest from curiosity.com to help you get smarter in just a few minutes. I'm Cody Gough.
ASHLEY HAMER: And I'm Ashley Hamer. Today you'll learn about why Christmas music sounds like Christmas, the crocodile paradox, what causes the smell of fresh rain, and how you can tell the National Science Foundation about your idea for their next project.
CODY GOUGH: Let's satisfy some curiosity.
ASHLEY HAMER: If you've walked into a store in the states in the last month, you've probably heard Christmas music. When you hear a Christmas song, you know it. But have you ever wondered, what is it about Christmas music that makes it so, well, Christmassy? Today we've got the science behind why hearing a Christmas song puts you in that Christmas spirit.
CODY GOUGH: And really, since this gets into psychology, this story isn't Christmas exclusive. It just seems like a kind of relevant example right about now.
ASHLEY HAMER: Totally. So psychologically, Christmas is associated with a lot of sensory stimuli that only show up one time of year-- the smell of gingerbread, the taste of candy canes, and yes, the traditional Christmas playlist. And the only time you're exposed to those things is during the holiday season, so you start to associate them with Christmas. That's called classical conditioning.
And just like your favorite bands from high school still hold a special place in your heart, Christmas songs can hold a special place in your memory because of how old you were when you heard them for the first time. That's what psychologists call a reminiscence bump. And songwriters use that to their advantage. Lots of classic Christmas songs were written during the Jazz Era.
So even with today's popular hits, you can sometimes hear upbeat jazz-inspired chords-- not to mention other classic sounds like church bells, trumpet fanfares, and sleigh bells. And of course, there are the classic rules of writing a song that sticks in your head. Simple melodies and chords that lend a sense of familiarity before throwing you a surprise once in a while.
Writing a great Christmas song is pretty much the same thing as writing a great song for any other time of year, only with those little reminiscence notes peppered in. With Christmas music, it's not enough to get it stuck in your head. It needs to nestle deep into your happiest holiday memories too.
CODY GOUGH: I feel like the classical conditioning is also why some people hate Christmas music, especially people who used to work in malls or stores.
ASHLEY HAMER: Definitely.
CODY GOUGH: Because I know a lot of people will say, oh, I hear the same songs all day. What's your favorite Christmas song?
ASHLEY HAMER: I have a weird relationship with Christmas music, and my favorite Christmas song is "What Are You Doing New Year's Eve?"
CODY GOUGH: That's not a Christmas song.
ASHLEY HAMER: But it's totally played with all the other Christmas music, so I think it counts.
CODY GOUGH: Who does that song?
ASHLEY HAMER: Oh, it's an old jazz standard.
CODY GOUGH: My favorite Christmas song is probably Burl Ives' "Holly Jolly Christmas."
ASHLEY HAMER: Oh, that's a good one.
CODY GOUGH: But for some reason, for the last two weeks, I've had Mariah Carey's "All I Want for Christmas is You" stuck on my head.
ASHLEY HAMER: [CHUCKLES] It's a classic.
CODY GOUGH: Is it?
ASHLEY HAMER: It's a modern classic.
CODY GOUGH: It's a modern classic. Non-stop. Cannot get it out. But that's fine. Up next, we're going to take a trip back in time. Earlier this year, a few hundred Curiosity Daily fans took our listener survey to help us understand what you like about our show. And we used those responses to identify your favorite stories from the past year.
ASHLEY HAMER: Starting now through the end of the year, we'll be bringing you our most popular stories to wrap up the holidays on a high note. We'll be back with all brand new episodes on January 2.
CODY GOUGH: Before we get to all that, I want to give a special shout-out to some of our patrons for supporting our show. Thank you, Minzai, John Friesen, Dave Brzezinski, and Mary, for your support this year.
ASHLEY HAMER: We also want to give a special shout-out to Dr. Mary Yancey who gets an executive producer credit today for her generous support on Patreon. Thank you so much for your support this year. It has made a huge difference for us.
CODY GOUGH: If you're listening and you want to support Curiosity Daily, then visit patreon.com/curiosity.com, all spelled out. Any amount helps, and we offer a lot of bonus material as our way of saying thanks to all our patrons, like bonus interviews and access to our Discord server. One more time, that's patreon.com/curiosity.com.
ASHLEY HAMER: And now here's some classic Curiosity Daily.
CODY GOUGH: We'll start off today with a little brain teaser. And by brain teaser, I mean self-contradictory or logically impossible statements, also known as a paradox, specifically an ancient Greek paradox. Ashley, do you have a favorite paradox?
ASHLEY HAMER: Yes. I believe it's, this statement is a lie.
CODY GOUGH: Is that the liar's paradox?
ASHLEY HAMER: Yes.
CODY GOUGH: I love the liar's paradox. I have something to say about the liar's paradox, but I'm going to save it till after we talk about this Greek one.
ASHLEY HAMER: Woo. All right.
CODY GOUGH: There's a little tease for you. Today we wrote about the crocodile paradox. And this is a logic problem that came from ancient Greece. Here's how it goes. A crocodile has captured a little kid. Being the reasonable crocodile that he is, the croc promises the kid's dad that he will release him only if the father can predict what the crocodile will do next. The kid's dad says, you will not give my son back.
Now the croc is in trouble. If the dad was correct in his statement, then the croc keeps the kid, right? But if the croc keeps the kid, then the croc is not keeping his promise to return the kid. But once the croc returns the kid, the dad's prediction is no longer correct. What should the crocodile do?
Spoiler alert, there is no answer. But that's the fun of paradoxes, right? As the philosopher Kierkegaard once said, quote, "The thinker without a paradox is like a lover without feeling," unquote. You can learn more about fun paradoxes like the first recorded paradox from the 6th-century BCE in our full write-up on curiosity.com and on the Curiosity app for Android and iOS.
And the liar's paradox, I love because I just saw Kirk and Spock use it on an android in Star Trek, the original series, in the episode I, Mudd. Kirk and Spock use the paradox to overload this machine, and that's kind of a sci-fi trope that if there's an android or other artificial intelligence, they'll use a paradox, like the liar's paradox, to kind of overload its circuits and then overcome it.
ASHLEY HAMER: Oh, wow. I wonder if we could feed a paradox to IBM Watson and see what happens.
CODY GOUGH: Oh.
ASHLEY HAMER: Cody, do you like the smell of new rain?
CODY GOUGH: I love everything associated with rain.
ASHLEY HAMER: Really?
CODY GOUGH: Yeah.
ASHLEY HAMER: You just like-- you like getting wet? You like puddles?
CODY GOUGH: I love rainy days. I love listening to the rain.
ASHLEY HAMER: Wow.
CODY GOUGH: Everything, and everything precipitation. I love when it snows. I'm just-- yeah.
ASHLEY HAMER: Do you like the smell?
CODY GOUGH: I think so. Yeah.
ASHLEY HAMER: I hate the smell.
CODY GOUGH: Really?
ASHLEY HAMER: Yeah. I don't know what it is. It's like dirt.
CODY GOUGH: [LAUGHS]
ASHLEY HAMER: Yeah. I don't like it. And you know what? I feel like I'm vindicated now that I know what it really is.
CODY GOUGH: Whoa.
ASHLEY HAMER: So a lot of research went into this, including work from a team of Australian scientists and a team of MIT scientists. And it was recently rounded up by Tim Logan, a professor of atmospheric sciences at Texas A&M University. He boiled down the answer into one word, petrichor. Cool. Problem solved. We can all go home. Just kidding.
Logan writes that petrichor is the chemical process that happens when rainwater meets dry earth. When the earth gets moist, it releases a cocktail of chemical compounds, including things like plant oils. But the most important ingredient in producing the smell of petrichor is a type of stinky alcohol called geosmin. It's produced by bacteria that live in the soil and break down whatever dead stuff happens to fall to the earth.
So rain plus dirt equals geosmin, which creates that telltale fresh rain smell. But you only get that with fresh rain because dryness slows down the geosmin-producing bacteria responsible for breaking down the organic matter in the soil. As the raindrops spatter the ground, they kick up geosmin-containing compounds in aerosol form.
Let a few gusts of wind stir things up, and presto. Your nose detects the geosmin and that unmistakable fresh rain smell. It can be strong enough that people downwind can catch a whiff and smell an approaching storm.
And even if you can't smell petrichor before the rain actually arrives, you might be able to sniff out another telltale sign a storm is brewing, ozone. The electric charge from lightning splits atmospheric nitrogen and oxygen molecules into separate atoms. Some of those recombine into nitric oxide, and sometimes that reacts with other atmospheric chemicals to produce a molecule made up of three oxygen atoms, ozone, that has a distinctly sharp scent. So yes, you really can smell rain coming. Isn't nature cool?
CODY GOUGH: So you're saying that it's caused by bacteria?
ASHLEY HAMER: It's bacteria farts
CODY GOUGH: [CHUCKLES]
ASHLEY HAMER: That's what it is.
CODY GOUGH: All right.
ASHLEY HAMER: [CHUCKLES]
CODY GOUGH: Well, you know what? I like the way it smells.
ASHLEY HAMER: That's just fine.
CODY GOUGH: Do you have a question you think science needs to answer? We have a smart audience made of people who have a lot of big questions. Yes, we're talking about you, listener. So today on Curiosity, we wrote about an organization that might be able to help. And this is not a paid placement, by the way. It's just a science thing. The sciencey people like to science it up.
Well if you're listening and you have a big question, starting this week, the National Science Foundation is accepting any and all suggestions for areas of research they may want to focus on. It's called the NSF 2026 Idea Machine, and you don't have to be a scientist or an engineer or even a high school graduate to participate. They're just looking for big ideas. And hey, you don't need to be an expert to have a big idea.
The head of NSF's office of integrative activities told Science Magazine, quote, "We don't want single projects, but rather big umbrella themes with lots of community engagement and involving all units at NSF," unquote. In other words, you don't have to figure out how to make your idea happen. You can leave that to the NSF-funded researchers.
Now as for specific types of big ideas, they're looking for things the NSF isn't already funding. That means they're probably not going to pick projects like a mission to Mars. Instead, focus on ideas with immediate or near-immediate impact or relevance. You can read about some of the things the NSF is working on in a full write-up on curiosity.com and on the Curiosity app for Android and iOS. And let us know if they pick your big idea for their next project.
ASHLEY HAMER: Read about today's stories and more on curiosity.com.
CODY GOUGH: Join us again tomorrow for more of the best stories of the year on the award-winning Curiosity Daily. I'm Cody Gough.
ASHLEY HAMER: And I'm Ashley Hamer. Stay curious.
NARRATOR: On the Westwood One Podcast Network.
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