3D Illustration of an atom, that is the smallest constituent unit of ordinary matter that has the properties of a chemical element.
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Molecules make up everything around us and they are very, very small. But those molecules are made of atoms, which are even smaller. And then those atoms are made up of protons, neutrons and electrons, which are even smaller. And protons are made up of even smaller particles called quarks.
Quarks, like electrons, are fundamental particles, which means they can’t be broken down into smaller parts. Or can they? In this episode we parse out the subatomic by talking with a physicist from Fermilab. We also hear how scientists’ love for glass tubes aided in the discovery of electrons. Our Moment of Um tackles this puzzler: why is chocolate poisonous to dogs? All that and a smoking hot Mystery Sound.
Sound effects from freesfx.co.uk
Audio Transcript
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MARY POOLE: You're listening to Brains On, where we're serious about being curious.
KID: Brains On is supported in part by a grant from the National Science Foundation
[SUSPENSEFUL MUSIC]
MALE SPEAKER 1: Run for your life!
FEMALE SPEAKER: Atoms! Millions upon billions upon trillions of them!
REPORTER: We interrupt this program to bring you an atom update. Well, it looks like there's more to these particles than we thought. There are actually smaller particles than atoms surrounding us and-- wait, wait! I'm being handed an update. They're passing through us right now. Oh, no! I fear this may be the end! Oh, I'm going to take a moment to speak directly to my mother. Mama, I love you!
MARY POOLE: Relax, atoms are nothing to be scared about. They help make up everything around us. They're great. In fact, in today's show, we're going to take a closer look at atoms and beyond.
[BOUNCY MUSIC]
MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom. And with me today is 10-year-old Mary Poole from Atlanta. Hi, Mary Poole.
MARY POOLE: Hi.
MOLLY BLOOM: Today we are looking at some pretty tiny particles, like atoms.
MARY POOLE: And we're going to get even smaller to figure out this question.
SPYRIDON: Hi, my name is Spyridon. And I'm from Taos, New Mexico. My question is, what are atoms made of?
MOLLY BLOOM: Now, Mary Poole, you actually wrote in with a very similar question. What got you thinking about this?
MARY POOLE: Well, in school, we were kind of learning about it. And we are also listening to your podcast. And we thought it would be really cool to send in a question. So we decided to just send in a question. And I really wanted to know what atoms were made of.
MOLLY BLOOM: Well, it is a really good question. So first, we're going to take a short trip to exactly where you are right now. Wherever you are, you are surrounded by atoms. In fact, you are atoms.
MARY POOLE: These are the smallest chemical elements in nature. And they combine together to make up everything.
MOLLY BLOOM: When atoms combine, they make molecules. So two hydrogen atoms and one oxygen atom equals H2O, or water.
MARY POOLE: Carbon dioxide, the air you're breathing out of your lungs, those molecules are made up of one carbon atom and two oxygen atoms, or CO2.
MOLLY BLOOM: And when you're sprinkling table salt onto your popcorn, the molecules that make up table salt are made up of one sodium atom and one chlorine atom, NaCl.
MARY POOLE: The ground underneath you-- molecules.
MOLLY BLOOM: The clouds above you-- molecules.
MARY POOLE: Your body-- molecules.
MOLLY BLOOM: The thing is, molecules are so small, we can't see an individual one with just our eyes. And if molecules are that small and molecules are made up of atoms, well, then atoms are even smaller.
MARY POOLE: And what about the parts of an atom?
MOLLY BLOOM: That was your question, after all. At the center of every atom is its nucleus. That's made up of protons and neutrons. We'll hear more about those in a few minutes. And then zooming around every atom's nucleus are electrons. So we've got a nucleus made up of protons and neutrons, and electrons zooming around it.
MARY POOLE: So if these subatomic particles that make up atoms are even smaller than very small atoms, how did we ever find them in the first place?
MOLLY BLOOM: For that story, producer Sanden Totten is going to give us a little-- and I really mean little-- history.
SANDEN TOTTEN: Once upon a time, scientists loved glass tubes. I mean, they still love glass tubes, but, like, back 200 years ago, they'd do all kinds of weird things with them.
[UPBEAT MUSIC]
One popular pastime was to take a glass tube and add in a negatively charged piece of metal, called a cathode, and a little further away from that, a positively charged piece of metal, called an anode. Next, you'd use a vacuum pump to try to suck some of the air out from the tube. And then you'd charge up those two plates and see what happens.
[ELECTRICITY BUZZING]
MALE SPEAKER 2: Good golly, miss Molly! The tube is glowing!
SANDEN TOTTEN: That's Heinrich Geissler, a German physicist and glassblower living in the 1800s. His tubes would glow when you ran the negative and positive charges into the cathode and anode. Very cool stuff.
MALE SPEAKER 2: Yeah, these were the forerunners of today's neon lights. So lovely.
SANDEN TOTTEN: Why were they glowing? What made them glow? Scientists figured it probably had to do with the electricity that they used to charge these metal plates. But they didn't really know what electricity was. Is it a liquid, kind of tiny, little atom things, or some kind of wavy thingy maybe? The answer, they thought, was in these glass tubes. And they were right. They just needed better vacuums.
MALE SPEAKER 3: My vacuums really sucked. I mean, they were good at sucking. I mean, they pulled out more air from tubes, yes, yes, yes.
SANDEN TOTTEN: That's British scientist William Crookes. By the 1870s, he was able to suck out a lot more air from these tubes. When he'd electrify those negative and positive metal plates in the tube, it wouldn't just glow all over inside. Instead, it would look like there was a beam of light passing from the negative plate to the positive plate. This was because there was less air in the tube.
So whatever was traveling from one plate to another wasn't exciting all these air molecules along the way, leading to that spread out kind of glow. Instead, it could travel directly from one place to another with nothing in the way.
MALE SPEAKER 3: Quite remarkable! It's like there's a ray sent from the cathode.
SANDEN TOTTEN: These became known as cathode rays because, of course, that's what you'd call them.
[JAZZY SCI-FI MUSIC]
Scientists studied these cathode rays a lot, using many, many, many glass tubes. They found that if you placed a magnet around a glass tube like this the cathode ray would actually bend toward the positive side of the magnet.
MALE SPEAKER 4: That means the ray must have a negative charge because negative wants to go positive. Opposites attract. [LAUGHS]
SANDEN TOTTEN: So along comes this British physicist, JJ Thompson. He does a lot of experiments on these rays. Not only does he see that the rays are negatively charged-- you know, because it bended toward the positive side of the magnet-- he also observes that whatever these rays are made up of, it must be very tiny stuff. He does a bunch of measurements and calculations. And he figures out they must be very, very small. So JJ, he has this big idea.
MALE SPEAKER 4: It's not a big idea. It's a small idea, the idea that maybe these rays are made up of particles that are so small they are smaller than atoms. And they're not just smaller than atoms. They're actually parts of atoms!
[FUNKY MUSIC]
SANDEN TOTTEN: OK, so, now, at the time, this is a bold statement because before old JJ, scientists thought the atom was as small as it got. It was, that's it. It was just the atom was the building block, and the atom was made up of the atom, that's it. But JJ argued there was actually even tinier things inside atoms, the things that made up atoms.
And he said these rays we were seeing, these cathode rays, they were actually letting us get a peek at these smaller-than-an-atom things, whatever they were.
MALE SPEAKER 4: I call them corpuscles.
SANDEN TOTTEN: Turns out, he was right about these things. Today we call them electrons.
MALE SPEAKER 4: Corpuscles are better.
SANDEN TOTTEN: Eh, agree to disagree. But it was JJ Thompson's ideas and experiments that helped us figure out that atoms aren't just a single solid thing. They have smaller parts too. And one of those parts is a teeny, tiny, negatively charged thing, called an electron.
MALE SPEAKER 4: A corpuscle!
SANDEN TOTTEN: Oh, come on, JJ. Really? [SIGHS]
MALE SPEAKER 4: Oh, very well-- [SIGHS] an electron.
SANDEN TOTTEN: Thank you. An electron. We discovered all this thanks to some really clever scientists and their weird obsession with glass tubes. Go figure. Back to you, Molly and Mary Poole.
MOLLY BLOOM: OK, so we've got electrons, and they're zooming around the center of an atom, its nucleus. But remember the other parts of an atom?
MARY POOLE: Protons and neutrons.
MOLLY BLOOM: Right. Now, we just heard that electrons have a negative charge. Protons have a positive charge. And neutrons have no charge at all. It's not positive or negative. It's the positive charge of a proton and negative charge of an electron that holds the atom together.
MARY POOLE: Opposites attract.
MOLLY BLOOM: Exactly. And if you want to find out more about how atoms combine with each other to form molecules, check out our episode on how paint sticks. There's a big old molecule party going on in that one.
MALE SPEAKER 5: (SINGING) Molecule party!
MOLLY BLOOM: All right, Mary Poole, we are taking a slight detour from atoms. It's time for the mystery sound.
[SHHH]
KID: (WHISPERING) Mystery sound.
MOLLY BLOOM: You ready to guess?
MARY POOLE: Yes.
MOLLY BLOOM: Here it is.
[MYSTERY SOUND]
OK, any guesses?
MARY POOLE: Rice coming into a cup?
MOLLY BLOOM: So like someone pouring rice into a cup, like before it's been cooked?
MARY POOLE: Uh-huh.
MOLLY BLOOM: Excellent guess. Well, we will play the sound again a little later in the show and see if you were right.
[GENTLE ROCK]
Are you a teacher using Brains On in the classroom? We're looking to provide more resources to educators like you. We've got discussion questions and Pinterest boards with activities perfect for post-listening lessons. To find out more, send an email to Hello@BrainsOn.org with the subject line "Teachers List."
MARY POOLE: Brains on is fueled by your mystery sounds, letters, drawings, and questions.
MOLLY BLOOM: Like this one, from Eliza in Denver, Colorado.
ELIZA: Why is chocolate poisonous to dogs?
MARY POOLE: If you want to get in touch, like Eliza, email us at Hello@BrainsOn.org.
MOLLY BLOOM: We'll answer her question in the Moment of Um and hear the newest addition to the Brains Honor Roll. That's all at the end of the show.
MARY POOLE: Stick around.
[MUSIC PLAYING]
FEMALE SPEAKER 3: Do you like stories? Then you'll love Circle Round, WBUR's new podcast for kids. We tell folk tales from around the world, with awesome actors from the stage and screen.
MALE SPEAKER 6: You are a genius!
FEMALE SPEAKER 3: Find Circle Round on ApplePodcasts.com/kids or wherever you get your podcasts.
MARY POOLE: You're listening to Brains On. I'm Mary Poole.
MOLLY BLOOM: And I'm Molly. OK, let's go back to that mystery sound. Are you ready to hear it one more time?
MARY POOLE: Yes.
MOLLY BLOOM: Here it is.
[MYSTERY SOUND]
OK, did hearing it again prompt any new thoughts about what it might be?
MARY POOLE: Yes, a rain chain.
MOLLY BLOOM: What's that?
MARY POOLE: It's like a-- when rain comes down, it goes into a little chain, and it makes like a little-- that type of sound.
MOLLY BLOOM: Oh, like from your roof. It just helps the rain go off your roof?
MARY POOLE: Uh-huh, yeah.
MOLLY BLOOM: You're teaching me things, Mary Poole.
MARY POOLE: [CHUCKLES]
MOLLY BLOOM: All right, well, let's hear the answer.
MARSHA OLSTEN: Hi, I'm Marsha Olsten from Olympia, Washington. And that was the sound of me putting out a campfire with water.
MOLLY BLOOM: Putting out a campfire with water.
MARY POOLE: Whoa.
MOLLY BLOOM: Have you done that before?
MARY POOLE: Yes
MOLLY BLOOM: So now that you hear that, does it make sense?
MARY POOLE: Yes.
MOLLY BLOOM: Still, water involved, just not rain water.
MALE SPEAKER 7: (SINGING) Ba-ba ba-ba ba-ba ba-ba-ba ba-- Brains On.
MARY POOLE: So far, we've talked about some of the smallest particles we know about-- atoms.
MOLLY BLOOM: And we've peeked behind the atomic curtain to see what they're made up of-- protons, neutrons, and electrons.
MARY POOLE: Which leads us to Bruce from Edmonds, Washington. He wrote in with this Puzzler.
BRUCE: My question is, is there anything smaller than an electron? Has anybody seen it?
MOLLY BLOOM: An electron is what's called a fundamental particle, meaning we can't break it down into anything smaller.
MARY POOLE: Protons, however, are made of quarks. Quarks are also a fundamental particle. We don't think they can be broken down into anything smaller.
MOLLY BLOOM: But within atoms, there are particles smaller than an electron.
MARY POOLE: Producer Marc Sanchez went in search of these particles. And he brought along a pal.
JASPER: I'm Jasper from Washington, DC.
MARC SANCHEZ: I asked Jasper to help me find the answer because--
JASPER: I've always been interested in physics. And a while ago, I heard and I read about subatomic particles, but it never once mentioned anything smaller than them. So I've just had a growing desire to learn about things smaller than subatomic particles.
MARC SANCHEZ: Jasper and I spoke with Kanika Sachdev. She's a physicist at Fermilab in Chicago, where they try to detect smaller and smaller particles. Kanika's specialty is very small. She looks into particles called neutrinos.
JASPER: I was wondering, are we done finding smaller particles? I mean, I know we've found a lot. I don't know all of them. But is it possible there are smaller things?
KANIKA SACHDEV: There actually are some small particles that we're still looking for. So the reason we go looking for things is that we study nature, and then we find something that happens in nature that we can't quite explain with all the particles that we already know about.
So dark matter is one of those things. So when we look out in the universe, we find that the rate at which the galaxies are rotating, it means that there must be more mass in the galaxies than we can see. So then we hypothesize; There must be something else out there that we can't see. And that's what dark matter is. So there certainly are more particles in nature than we have discovered, so far.
And the reason we go looking for them is because the world, as we observe it, doesn't quite make sense without imagining something more than we've already observed. So we're far from done. [CHUCKLES]
JASPER: Are there ways of measuring particles smaller than electrons or protons, neutrons, stuff like that?
KANIKA SACHDEV: Yeah, so it depends upon what the properties of that particular are. So there are certain particles which are, quote-unquote, smaller than electron. One of those particles is a neutrino. And that's the one that I work with. So the way we study these particles is most of these particles, you cannot observe directly. So if you want to see a particle in your detector, that particle has to have some charge.
So an electron has a negative charge. So as the electron goes through your detector, it produces some light, and then you can see it. Similarly, if a positively charged particle goes through your detector, you can see it. But if a particle is neutral, for example, a neutrino is a neutral particle-- that is, it does not have any positive or negative charge-- so when it passes through your detector, you cannot see it at all. It just blows right through it.
And you would never see it, except very occasionally, what happens is that as a neutrino is going through your detector, it just happens to hit an atom inside of your detector. So when the neutrino hits an atom or a nucleus inside of your detector, then it produces a splash of energy. It's basically like a small, tiny billiard ball coming in and hitting the other balls. And then all the other billiard balls will just go around and hit the walls of the billiards table.
So that's what we see. So a neutrino quietly comes into the detector, it hits something, and then it produces-- the something that it hits, it just explodes. And then you see tiny particles coming out of the nucleus. So that's how we observe particles. And that's one of the ways we observe neutrinos, which are smaller than the electron.
MARC SANCHEZ: There are different ways to measure particles. One way a neutrino is smaller than an electron is by its mass. When it comes to mass, a neutrino is about a million times lighter than an electron. And that's not all.
KANIKA SACHDEV: The model of the universe, that we have, standard model is what we call it. And most of the predictions of the standard model have been experimentally confirmed. But there are some experiments that we have done where we don't really understand what's going on. So for instance, we don't understand what dark matter is. We don't really understand what dark energy is. We don't really understand what the fundamental nature of all of these particles is.
So when I say, an electron is a fundamental particle; There's nothing more to an electron but an electron itself. Now, is that really a true statement? There's models out there which say that all of these particles are made up of something else. For instance, there's the string theory, which says that particles are made up of strings. Is that really true? [CHUCKLES] We don't really know yet.
And none of the experiments that we have done show that there are strings or any such thing. But this is an ongoing quest. And I don't think we're anywhere near the answers yet.
MARC SANCHEZ: String theory, dark matter, dark energy, all these things that Kanika and the people at Fermilab and scientists all over the world are trying to find, they're smaller than electrons. They're smaller than we can even imagine. But when you put them all together, they make up everything we know.
[JAZZY SCI-FI MUSIC]
MOLLY BLOOM: Atoms are the smallest natural elements we know of.
MARY POOLE: They combine to make molecules, which make up pretty much everything around us.
MOLLY BLOOM: Atoms are made up of protons, neutrons, and electrons.
MARY POOLE: Fundamental particles like quarks and electrons can't be broken down into smaller pieces.
MOLLY BLOOM: We know neutrinos are smaller than an electron if you measure their mass. And there might be smaller particles too.
MARY POOLE: Scientists are still on the hunt for them.
[LIGHT ROCK]
MOLLY BLOOM: That's it for this episode of Brains On.
MARY POOLE: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: And Brains On is made possible, in part, by a grant from the National Science Foundation.
MARY POOLE: We had audio help from Johnny Vince Evans, Jim Schultz, Kevin Rinker, and Veronica Rodriguez.
MOLLY BLOOM: Special thanks to Parker and Leanne Smith, Michael Wallason, Vicki Shabo, Jamie Olson, Julia Majors, at the American Institute of Physics, Emily Allen, John Lambert, Lauren Dee, Hans Buetow, Vicki Kreckler, John Raby, John Cohen, and Jason Georges.
MARY POOLE: So is that it? Are we done?
MOLLY BLOOM: Almost.
MARY POOLE: Oh, yeah, time for some chocolate.
MOLLY BLOOM: Except not for dogs. No chocolate for dogs.
MARY POOLE: And why is that? It's kind of like a Moment of Um.
[UMS AND UHS]
ELIZA: Hello, my name is Eliza, from Denver, Colorado. And my question is, why is chocolate poisonous to dogs?
CASSIE PANNING: My name is Cassie Panning. I am a certified veterinary technician here at the University of Minnesota. And I work primarily in the nutrition service.
[CLASSICAL MUSIC]
We do nutrition appointments for dogs. So we help with things like dietary recommendations for new puppies or large breed growing dogs. We also do a lot of obesity cases to help pets lose weight in a healthy manner, as well as making specific dietary recommendations if they have certain medical conditions that require a special or "tailored to their individual needs" diet.
Dogs can't eat chocolate in the same way humans can because humans have a specific enzyme that helps break down the theobromine, which is a component of the chocolate that, in dogs, because they have a lot less of that enzyme, can build to toxic levels for the dogs when they eat the chocolate, unlike in humans.
Same as if you or I went ahead and ate the whole bag of our Halloween candy; We might not have life-threatening symptoms, but we're probably going to have an upset stomach, so some stomach pain; We might get a little bit of vomiting or diarrhea. Same with our dogs. When they ingest the products, especially in larger quantities, we absolutely can see it caused that upset stomach first.
And then as their levels build and they get more and more of those toxic components, we end up seeing the things, like their heart starts racing or their blood pressure goes way up, which can, again, lead to more life threatening symptoms if left untreated.
[UMS AND UHS]
MOLLY BLOOM: Let's put a cherry on this chocolate cake.
MARY POOLE: It's time to hand out high fives to the kids who shared their ideas and questions with us. Here are the latest additions to the Brains Honor Roll.
[ELECTRONIC MUSIC]
MOLLY BLOOM: [LISTING HONOR ROLL]
(SINGING) Brains Honor Roll. High-five.
[RHYTHMIC CLAPPING]
[LIGHT ROCK]
MOLLY BLOOM: Remember, if you want your name added to the Honor Roll, send your questions, mystery sounds, drawings, and letters to Hello@BrainsOn.org. We'll be back soon with more answers to your questions.
MARY POOLE: Thanks for listening.
KID: Brains On is supported in part by a grant from the National Science Foundation
[SUSPENSEFUL MUSIC]
MALE SPEAKER 1: Run for your life!
FEMALE SPEAKER: Atoms! Millions upon billions upon trillions of them!
REPORTER: We interrupt this program to bring you an atom update. Well, it looks like there's more to these particles than we thought. There are actually smaller particles than atoms surrounding us and-- wait, wait! I'm being handed an update. They're passing through us right now. Oh, no! I fear this may be the end! Oh, I'm going to take a moment to speak directly to my mother. Mama, I love you!
MARY POOLE: Relax, atoms are nothing to be scared about. They help make up everything around us. They're great. In fact, in today's show, we're going to take a closer look at atoms and beyond.
[BOUNCY MUSIC]
MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom. And with me today is 10-year-old Mary Poole from Atlanta. Hi, Mary Poole.
MARY POOLE: Hi.
MOLLY BLOOM: Today we are looking at some pretty tiny particles, like atoms.
MARY POOLE: And we're going to get even smaller to figure out this question.
SPYRIDON: Hi, my name is Spyridon. And I'm from Taos, New Mexico. My question is, what are atoms made of?
MOLLY BLOOM: Now, Mary Poole, you actually wrote in with a very similar question. What got you thinking about this?
MARY POOLE: Well, in school, we were kind of learning about it. And we are also listening to your podcast. And we thought it would be really cool to send in a question. So we decided to just send in a question. And I really wanted to know what atoms were made of.
MOLLY BLOOM: Well, it is a really good question. So first, we're going to take a short trip to exactly where you are right now. Wherever you are, you are surrounded by atoms. In fact, you are atoms.
MARY POOLE: These are the smallest chemical elements in nature. And they combine together to make up everything.
MOLLY BLOOM: When atoms combine, they make molecules. So two hydrogen atoms and one oxygen atom equals H2O, or water.
MARY POOLE: Carbon dioxide, the air you're breathing out of your lungs, those molecules are made up of one carbon atom and two oxygen atoms, or CO2.
MOLLY BLOOM: And when you're sprinkling table salt onto your popcorn, the molecules that make up table salt are made up of one sodium atom and one chlorine atom, NaCl.
MARY POOLE: The ground underneath you-- molecules.
MOLLY BLOOM: The clouds above you-- molecules.
MARY POOLE: Your body-- molecules.
MOLLY BLOOM: The thing is, molecules are so small, we can't see an individual one with just our eyes. And if molecules are that small and molecules are made up of atoms, well, then atoms are even smaller.
MARY POOLE: And what about the parts of an atom?
MOLLY BLOOM: That was your question, after all. At the center of every atom is its nucleus. That's made up of protons and neutrons. We'll hear more about those in a few minutes. And then zooming around every atom's nucleus are electrons. So we've got a nucleus made up of protons and neutrons, and electrons zooming around it.
MARY POOLE: So if these subatomic particles that make up atoms are even smaller than very small atoms, how did we ever find them in the first place?
MOLLY BLOOM: For that story, producer Sanden Totten is going to give us a little-- and I really mean little-- history.
SANDEN TOTTEN: Once upon a time, scientists loved glass tubes. I mean, they still love glass tubes, but, like, back 200 years ago, they'd do all kinds of weird things with them.
[UPBEAT MUSIC]
One popular pastime was to take a glass tube and add in a negatively charged piece of metal, called a cathode, and a little further away from that, a positively charged piece of metal, called an anode. Next, you'd use a vacuum pump to try to suck some of the air out from the tube. And then you'd charge up those two plates and see what happens.
[ELECTRICITY BUZZING]
MALE SPEAKER 2: Good golly, miss Molly! The tube is glowing!
SANDEN TOTTEN: That's Heinrich Geissler, a German physicist and glassblower living in the 1800s. His tubes would glow when you ran the negative and positive charges into the cathode and anode. Very cool stuff.
MALE SPEAKER 2: Yeah, these were the forerunners of today's neon lights. So lovely.
SANDEN TOTTEN: Why were they glowing? What made them glow? Scientists figured it probably had to do with the electricity that they used to charge these metal plates. But they didn't really know what electricity was. Is it a liquid, kind of tiny, little atom things, or some kind of wavy thingy maybe? The answer, they thought, was in these glass tubes. And they were right. They just needed better vacuums.
MALE SPEAKER 3: My vacuums really sucked. I mean, they were good at sucking. I mean, they pulled out more air from tubes, yes, yes, yes.
SANDEN TOTTEN: That's British scientist William Crookes. By the 1870s, he was able to suck out a lot more air from these tubes. When he'd electrify those negative and positive metal plates in the tube, it wouldn't just glow all over inside. Instead, it would look like there was a beam of light passing from the negative plate to the positive plate. This was because there was less air in the tube.
So whatever was traveling from one plate to another wasn't exciting all these air molecules along the way, leading to that spread out kind of glow. Instead, it could travel directly from one place to another with nothing in the way.
MALE SPEAKER 3: Quite remarkable! It's like there's a ray sent from the cathode.
SANDEN TOTTEN: These became known as cathode rays because, of course, that's what you'd call them.
[JAZZY SCI-FI MUSIC]
Scientists studied these cathode rays a lot, using many, many, many glass tubes. They found that if you placed a magnet around a glass tube like this the cathode ray would actually bend toward the positive side of the magnet.
MALE SPEAKER 4: That means the ray must have a negative charge because negative wants to go positive. Opposites attract. [LAUGHS]
SANDEN TOTTEN: So along comes this British physicist, JJ Thompson. He does a lot of experiments on these rays. Not only does he see that the rays are negatively charged-- you know, because it bended toward the positive side of the magnet-- he also observes that whatever these rays are made up of, it must be very tiny stuff. He does a bunch of measurements and calculations. And he figures out they must be very, very small. So JJ, he has this big idea.
MALE SPEAKER 4: It's not a big idea. It's a small idea, the idea that maybe these rays are made up of particles that are so small they are smaller than atoms. And they're not just smaller than atoms. They're actually parts of atoms!
[FUNKY MUSIC]
SANDEN TOTTEN: OK, so, now, at the time, this is a bold statement because before old JJ, scientists thought the atom was as small as it got. It was, that's it. It was just the atom was the building block, and the atom was made up of the atom, that's it. But JJ argued there was actually even tinier things inside atoms, the things that made up atoms.
And he said these rays we were seeing, these cathode rays, they were actually letting us get a peek at these smaller-than-an-atom things, whatever they were.
MALE SPEAKER 4: I call them corpuscles.
SANDEN TOTTEN: Turns out, he was right about these things. Today we call them electrons.
MALE SPEAKER 4: Corpuscles are better.
SANDEN TOTTEN: Eh, agree to disagree. But it was JJ Thompson's ideas and experiments that helped us figure out that atoms aren't just a single solid thing. They have smaller parts too. And one of those parts is a teeny, tiny, negatively charged thing, called an electron.
MALE SPEAKER 4: A corpuscle!
SANDEN TOTTEN: Oh, come on, JJ. Really? [SIGHS]
MALE SPEAKER 4: Oh, very well-- [SIGHS] an electron.
SANDEN TOTTEN: Thank you. An electron. We discovered all this thanks to some really clever scientists and their weird obsession with glass tubes. Go figure. Back to you, Molly and Mary Poole.
MOLLY BLOOM: OK, so we've got electrons, and they're zooming around the center of an atom, its nucleus. But remember the other parts of an atom?
MARY POOLE: Protons and neutrons.
MOLLY BLOOM: Right. Now, we just heard that electrons have a negative charge. Protons have a positive charge. And neutrons have no charge at all. It's not positive or negative. It's the positive charge of a proton and negative charge of an electron that holds the atom together.
MARY POOLE: Opposites attract.
MOLLY BLOOM: Exactly. And if you want to find out more about how atoms combine with each other to form molecules, check out our episode on how paint sticks. There's a big old molecule party going on in that one.
MALE SPEAKER 5: (SINGING) Molecule party!
MOLLY BLOOM: All right, Mary Poole, we are taking a slight detour from atoms. It's time for the mystery sound.
[SHHH]
KID: (WHISPERING) Mystery sound.
MOLLY BLOOM: You ready to guess?
MARY POOLE: Yes.
MOLLY BLOOM: Here it is.
[MYSTERY SOUND]
OK, any guesses?
MARY POOLE: Rice coming into a cup?
MOLLY BLOOM: So like someone pouring rice into a cup, like before it's been cooked?
MARY POOLE: Uh-huh.
MOLLY BLOOM: Excellent guess. Well, we will play the sound again a little later in the show and see if you were right.
[GENTLE ROCK]
Are you a teacher using Brains On in the classroom? We're looking to provide more resources to educators like you. We've got discussion questions and Pinterest boards with activities perfect for post-listening lessons. To find out more, send an email to Hello@BrainsOn.org with the subject line "Teachers List."
MARY POOLE: Brains on is fueled by your mystery sounds, letters, drawings, and questions.
MOLLY BLOOM: Like this one, from Eliza in Denver, Colorado.
ELIZA: Why is chocolate poisonous to dogs?
MARY POOLE: If you want to get in touch, like Eliza, email us at Hello@BrainsOn.org.
MOLLY BLOOM: We'll answer her question in the Moment of Um and hear the newest addition to the Brains Honor Roll. That's all at the end of the show.
MARY POOLE: Stick around.
[MUSIC PLAYING]
FEMALE SPEAKER 3: Do you like stories? Then you'll love Circle Round, WBUR's new podcast for kids. We tell folk tales from around the world, with awesome actors from the stage and screen.
MALE SPEAKER 6: You are a genius!
FEMALE SPEAKER 3: Find Circle Round on ApplePodcasts.com/kids or wherever you get your podcasts.
MARY POOLE: You're listening to Brains On. I'm Mary Poole.
MOLLY BLOOM: And I'm Molly. OK, let's go back to that mystery sound. Are you ready to hear it one more time?
MARY POOLE: Yes.
MOLLY BLOOM: Here it is.
[MYSTERY SOUND]
OK, did hearing it again prompt any new thoughts about what it might be?
MARY POOLE: Yes, a rain chain.
MOLLY BLOOM: What's that?
MARY POOLE: It's like a-- when rain comes down, it goes into a little chain, and it makes like a little-- that type of sound.
MOLLY BLOOM: Oh, like from your roof. It just helps the rain go off your roof?
MARY POOLE: Uh-huh, yeah.
MOLLY BLOOM: You're teaching me things, Mary Poole.
MARY POOLE: [CHUCKLES]
MOLLY BLOOM: All right, well, let's hear the answer.
MARSHA OLSTEN: Hi, I'm Marsha Olsten from Olympia, Washington. And that was the sound of me putting out a campfire with water.
MOLLY BLOOM: Putting out a campfire with water.
MARY POOLE: Whoa.
MOLLY BLOOM: Have you done that before?
MARY POOLE: Yes
MOLLY BLOOM: So now that you hear that, does it make sense?
MARY POOLE: Yes.
MOLLY BLOOM: Still, water involved, just not rain water.
MALE SPEAKER 7: (SINGING) Ba-ba ba-ba ba-ba ba-ba-ba ba-- Brains On.
MARY POOLE: So far, we've talked about some of the smallest particles we know about-- atoms.
MOLLY BLOOM: And we've peeked behind the atomic curtain to see what they're made up of-- protons, neutrons, and electrons.
MARY POOLE: Which leads us to Bruce from Edmonds, Washington. He wrote in with this Puzzler.
BRUCE: My question is, is there anything smaller than an electron? Has anybody seen it?
MOLLY BLOOM: An electron is what's called a fundamental particle, meaning we can't break it down into anything smaller.
MARY POOLE: Protons, however, are made of quarks. Quarks are also a fundamental particle. We don't think they can be broken down into anything smaller.
MOLLY BLOOM: But within atoms, there are particles smaller than an electron.
MARY POOLE: Producer Marc Sanchez went in search of these particles. And he brought along a pal.
JASPER: I'm Jasper from Washington, DC.
MARC SANCHEZ: I asked Jasper to help me find the answer because--
JASPER: I've always been interested in physics. And a while ago, I heard and I read about subatomic particles, but it never once mentioned anything smaller than them. So I've just had a growing desire to learn about things smaller than subatomic particles.
MARC SANCHEZ: Jasper and I spoke with Kanika Sachdev. She's a physicist at Fermilab in Chicago, where they try to detect smaller and smaller particles. Kanika's specialty is very small. She looks into particles called neutrinos.
JASPER: I was wondering, are we done finding smaller particles? I mean, I know we've found a lot. I don't know all of them. But is it possible there are smaller things?
KANIKA SACHDEV: There actually are some small particles that we're still looking for. So the reason we go looking for things is that we study nature, and then we find something that happens in nature that we can't quite explain with all the particles that we already know about.
So dark matter is one of those things. So when we look out in the universe, we find that the rate at which the galaxies are rotating, it means that there must be more mass in the galaxies than we can see. So then we hypothesize; There must be something else out there that we can't see. And that's what dark matter is. So there certainly are more particles in nature than we have discovered, so far.
And the reason we go looking for them is because the world, as we observe it, doesn't quite make sense without imagining something more than we've already observed. So we're far from done. [CHUCKLES]
JASPER: Are there ways of measuring particles smaller than electrons or protons, neutrons, stuff like that?
KANIKA SACHDEV: Yeah, so it depends upon what the properties of that particular are. So there are certain particles which are, quote-unquote, smaller than electron. One of those particles is a neutrino. And that's the one that I work with. So the way we study these particles is most of these particles, you cannot observe directly. So if you want to see a particle in your detector, that particle has to have some charge.
So an electron has a negative charge. So as the electron goes through your detector, it produces some light, and then you can see it. Similarly, if a positively charged particle goes through your detector, you can see it. But if a particle is neutral, for example, a neutrino is a neutral particle-- that is, it does not have any positive or negative charge-- so when it passes through your detector, you cannot see it at all. It just blows right through it.
And you would never see it, except very occasionally, what happens is that as a neutrino is going through your detector, it just happens to hit an atom inside of your detector. So when the neutrino hits an atom or a nucleus inside of your detector, then it produces a splash of energy. It's basically like a small, tiny billiard ball coming in and hitting the other balls. And then all the other billiard balls will just go around and hit the walls of the billiards table.
So that's what we see. So a neutrino quietly comes into the detector, it hits something, and then it produces-- the something that it hits, it just explodes. And then you see tiny particles coming out of the nucleus. So that's how we observe particles. And that's one of the ways we observe neutrinos, which are smaller than the electron.
MARC SANCHEZ: There are different ways to measure particles. One way a neutrino is smaller than an electron is by its mass. When it comes to mass, a neutrino is about a million times lighter than an electron. And that's not all.
KANIKA SACHDEV: The model of the universe, that we have, standard model is what we call it. And most of the predictions of the standard model have been experimentally confirmed. But there are some experiments that we have done where we don't really understand what's going on. So for instance, we don't understand what dark matter is. We don't really understand what dark energy is. We don't really understand what the fundamental nature of all of these particles is.
So when I say, an electron is a fundamental particle; There's nothing more to an electron but an electron itself. Now, is that really a true statement? There's models out there which say that all of these particles are made up of something else. For instance, there's the string theory, which says that particles are made up of strings. Is that really true? [CHUCKLES] We don't really know yet.
And none of the experiments that we have done show that there are strings or any such thing. But this is an ongoing quest. And I don't think we're anywhere near the answers yet.
MARC SANCHEZ: String theory, dark matter, dark energy, all these things that Kanika and the people at Fermilab and scientists all over the world are trying to find, they're smaller than electrons. They're smaller than we can even imagine. But when you put them all together, they make up everything we know.
[JAZZY SCI-FI MUSIC]
MOLLY BLOOM: Atoms are the smallest natural elements we know of.
MARY POOLE: They combine to make molecules, which make up pretty much everything around us.
MOLLY BLOOM: Atoms are made up of protons, neutrons, and electrons.
MARY POOLE: Fundamental particles like quarks and electrons can't be broken down into smaller pieces.
MOLLY BLOOM: We know neutrinos are smaller than an electron if you measure their mass. And there might be smaller particles too.
MARY POOLE: Scientists are still on the hunt for them.
[LIGHT ROCK]
MOLLY BLOOM: That's it for this episode of Brains On.
MARY POOLE: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: And Brains On is made possible, in part, by a grant from the National Science Foundation.
MARY POOLE: We had audio help from Johnny Vince Evans, Jim Schultz, Kevin Rinker, and Veronica Rodriguez.
MOLLY BLOOM: Special thanks to Parker and Leanne Smith, Michael Wallason, Vicki Shabo, Jamie Olson, Julia Majors, at the American Institute of Physics, Emily Allen, John Lambert, Lauren Dee, Hans Buetow, Vicki Kreckler, John Raby, John Cohen, and Jason Georges.
MARY POOLE: So is that it? Are we done?
MOLLY BLOOM: Almost.
MARY POOLE: Oh, yeah, time for some chocolate.
MOLLY BLOOM: Except not for dogs. No chocolate for dogs.
MARY POOLE: And why is that? It's kind of like a Moment of Um.
[UMS AND UHS]
ELIZA: Hello, my name is Eliza, from Denver, Colorado. And my question is, why is chocolate poisonous to dogs?
CASSIE PANNING: My name is Cassie Panning. I am a certified veterinary technician here at the University of Minnesota. And I work primarily in the nutrition service.
[CLASSICAL MUSIC]
We do nutrition appointments for dogs. So we help with things like dietary recommendations for new puppies or large breed growing dogs. We also do a lot of obesity cases to help pets lose weight in a healthy manner, as well as making specific dietary recommendations if they have certain medical conditions that require a special or "tailored to their individual needs" diet.
Dogs can't eat chocolate in the same way humans can because humans have a specific enzyme that helps break down the theobromine, which is a component of the chocolate that, in dogs, because they have a lot less of that enzyme, can build to toxic levels for the dogs when they eat the chocolate, unlike in humans.
Same as if you or I went ahead and ate the whole bag of our Halloween candy; We might not have life-threatening symptoms, but we're probably going to have an upset stomach, so some stomach pain; We might get a little bit of vomiting or diarrhea. Same with our dogs. When they ingest the products, especially in larger quantities, we absolutely can see it caused that upset stomach first.
And then as their levels build and they get more and more of those toxic components, we end up seeing the things, like their heart starts racing or their blood pressure goes way up, which can, again, lead to more life threatening symptoms if left untreated.
[UMS AND UHS]
MOLLY BLOOM: Let's put a cherry on this chocolate cake.
MARY POOLE: It's time to hand out high fives to the kids who shared their ideas and questions with us. Here are the latest additions to the Brains Honor Roll.
[ELECTRONIC MUSIC]
MOLLY BLOOM: [LISTING HONOR ROLL]
(SINGING) Brains Honor Roll. High-five.
[RHYTHMIC CLAPPING]
[LIGHT ROCK]
MOLLY BLOOM: Remember, if you want your name added to the Honor Roll, send your questions, mystery sounds, drawings, and letters to Hello@BrainsOn.org. We'll be back soon with more answers to your questions.
MARY POOLE: Thanks for listening.
Transcription services provided by 3Play Media.
