Science is a powerful fact-finding tool -- but how does it work? In this second installment in our series "Prove It: How to find the facts," we look to the past for answers. We find out how a snake heart helped get rid of an old idea about blood and how failed experiments are just as important as successful ones (bye bye, luminiferous ether). And we'll hear from scientists working today about how curiosity is at the heart of science.

Plus: a mystery sound and our Moment of Um tackles this question: “Where do snails get their shells?”

Listen to the rest of the series:
Part one: A brief history of facts
Part two: Science under the microscope
Part three: The scoop on journalism
Part four: How to find the facts

Audio Transcript

Download transcript (PDF)

KATIE: You're listening to Brains On, where we're serious about being curious.

BOY: Brains On is supported in part by a grant from the National Science Foundation.

MAN: Did you disarm the security system?


MAN: And the museum guard?

WOMAN: Switched his coffee to decaf. He's out like a light.

MAN: And the dogs?

WOMAN: Gave him a laptop full of squirrel videos. They're good.

MAN: What?

WOMAN: I mean, it's mostly stuff I shot myself, but I tried to do some interesting things with the camera angles. And I think it turned out pretty--

MAN: You have the dogs homemade videos?

WOMAN: I told them they can log into my Netflix account if they get bored, but I think they're into the squirrel content, so.

MAN: Fine. Whatever. As long as they're occupied. Now how do we get this diamond out of this case?

WOMAN: Random thought, why don't we take that painting instead? I think it would match our rug.

MAN: We're not here for a painting.

WOMAN: It's just our living room really needs a conversation starter, and that painting would draw the eye.

MAN: Focus. We're here for one thing only, the world's largest diamond.

WOMAN: OK, fine. But what are we even going to do with a really big diamond?

MAN: Are you kidding me? What won't we do? Diamonds are the strongest material in the world.

WOMAN: Right. But is that even true?

MAN: Of course it's true. Everyone knows it's true.

WOMAN: It's just there have been some major advancements in man-made materials lately. And how do we even measure the strength of a material?

MAN: Are you kidding me right now?

GUARD: It's worth looking into.

MAN: Who said that?

GUARD: Oh, it's me, the guard. I woke up because I had to pee. By the way, you're both under arrest.

MOLLY BLOOM: This is part two in our series Prove It, How to find the facts. If you haven't heard part one, you might want to check your feed and start there. OK. Here we go.

MAN: (SINGING) How can we debate what we declare?

WOMAN: (SINGING) Theorize and test for errors.

MAN: (SINGING) What if what we say feels right?

WOMAN: (WOMAN) OK, sure. But let's just shine a light.

MAN AND WOMAN: (SINGING) We can prove it. We can prove it. Let's check the facts and prove it.

We can prove it. We can prove it. Let's check the facts and prove it.

Prove it.


MOLLY BLOOM: This is Brains On. I'm Molly Bloom, and my cohost for this series is 12-year-old Katie from Fairfield, Connecticut. Hi, Katie.


MOLLY BLOOM: So Katie, we're talking science today. If you could study any branch of science, which would you choose and why?

KATIE: Well, I really like biology. We learned about it in school now actually. I really like just studying life.

It's cool. It's amazing how Earth can hold so much life when no other planet can.

MOLLY BLOOM: Yeah, it is really amazing. And what do you think science and journalism have in common?

KATIE: Well, I think science and journalism have one major thing in common. They both need to be well-researched, and the information needs to be accurate.

MOLLY BLOOM: And do you think like journalists and scientists have some things in common too?

KATIE: Yeah. They both have to do their research. You can't do a science experiment if you think plants don't need sunlight.

MOLLY BLOOM: Very true. You kind of have to have a base level of knowledge to get started. OK, let's see how the science stacks up for that claim we heard earlier. We heard this one from listener, Finley.

FINLEY: Hi, my name is Finley. I am from Malibu, California. I have heard that diamonds are the strongest material in the world. And how do we know it's true?

MOLLY BLOOM: Let's bring back our fact-checking buddy Linda Qiu from The New York Times. Hi, Linda.


KATIE: Hi. Are diamonds the strongest material on Earth?

LINDA QIU: So we used to think that was true until 2015 when scientists made a new material out of carbon, which is the same thing that diamonds are made out of. They call it Q-carbon. It's even harder than diamonds. But other scientists haven't been able to replicate that experiment yet, so it's not certain.

So for now, think of it as Q-carbon is challenging diamonds for the top spot, but the results aren't really conclusive.

KATIE: That's really interesting.

MOLLY BLOOM: So the answer is maybe. It might be. [CHUCKLES] So how did you go about checking that fact?

LINDA QIU: Right. So I just googled hardest material in the world, and that brought me to a bunch of news write-ups of this 2015 study that came out about Q-carbon. And then I thought, what does that really mean?

So I went to this website called The Conversation, and it's where scientists write blog posts describing their areas of expertise. And this guy who studies material sciences wrote up a really thorough explanation for what hardness means. And so from there, I learned that like scientists actually have a very specific way of measuring hardness. And this is how we can tell that diamonds are the hardest because they scored the top level in this measure.

MOLLY BLOOM: And where did you find the information about how no one's been able to replicate the Q-carbon?

LINDA QIU: I couldn't find anything else after 2015 on Q-carbon, except for a couple of quotes saying like, this is really interesting. I'm still in-- I still want to look into it. So in Google Scholar, which is Google's database, for scholarly research, I wasn't able to find any other studies on Q-carbon after 2015.

KATIE: Well, thank you so much, Linda, for checking that fact for us today.

LINDA QIU: Thanks for having me.


MOLLY BLOOM: Science has helped humans find facts about the world for thousands of years. So it only makes sense that we're going to answer this question today.

JADE: My name is Jade. I'm nine years old. I'm from Sydney, Australia.

And my question is, how does science work?

KATIE: It's a big question, so we asked some of our scientist friends to help us answer it. And we asked them to do it in 10 words or less.

SCIENTIST 1: That's easy. Think of something new, test it, observe, revise, and repeat.

SCIENTIST 2: Science works by turning curiosity into knowledge.

SCIENTIST 3: Science works on the basis of facts, not someone's opinion.

SCIENTIST 4: Science works by asking questions and designing studies to collect data to answer those questions.

SCIENTIST 5: Science works to predict the world through a process of asking questions, making observations, and evaluating ideas.

SCIENTIST 6: Science works with questions and experiments.

SCIENTIST 7: To me, science is being Sherlock Holmes, solving mysteries of all earthly things. Fun.

MOLLY BLOOM: That was [? Eli Norbosh, ?] Diana Dragomir, Raychelle Burks, Graciela Unguez, Nick Caruso, Gitanjali Rao, and Emilie Snell-Rood. And you can meet all these brilliant scientists in past episodes of Brains On. Head to to find them.

KATIE: There's no one magic way to do science. But at its core, science is this--

MOLLY BLOOM: It's a rigorous examination of the world around us.

KATIE: And people were doing this long before we called it science.

MOLLY BLOOM: Back then, we call these people philosophers or naturalists or doctors, but any way you slice it, it was still science, that rigorous examination of the world.

ALEXANDRA HUI: What counts as rigorous changes all the time.

KATIE: That's Alex Hui. She's a science historian at Mississippi State University.

MOLLY BLOOM: But even though the exact methods used have changed, science has some basic characteristics. There's repetition.

ALEXANDRA HUI: And if someone's doing the same experiment every single day for three years or they go around the world following different eclipses in order to make observations of eclipses--

MOLLY BLOOM: It has to be replicable, meaning that if a scientist finds something in an experiment, other scientists should be able to recreate it and find the same thing.

ALEXANDRA HUI: There's also these qualities of a scientist that make them rigorous. So they're disinterested, and they're objective, these kinds of qualities that allow them to think beyond themselves.

MOLLY BLOOM: Science is also about precision. In the 1700s, tools like thermometers, scales, and other instruments of measurement were becoming more exact and consistent. And they've just gotten better and better ever since.

OK, so science is about objectivity, precision, repetition, and curiosity. But it's also about creativity, being able to think about things differently.

ALEXANDRA HUI: So let me talk about William Harvey then.

MAN: Me? Really? Little old me? No. What's there to say?

MOLLY BLOOM: He was a British scientist working in the 1600s, so 400 years ago. And he wanted to learn about how our bodies work.

MAN: Yeah, like what's the deal with blood?

MOLLY BLOOM: Back then, people thought that blood came from the liver.

ALEXANDRA HUI: And then just kind of like sloshed around the body until it reached the part where it needed to be and would be absorbed.

MAN: In my day, we had no fancy machines to see inside bodies. If you wanted to find out what's going on in there, well, you had to cut a body open. And as you can imagine, it's hard to find volunteers.

ALEXANDRA HUI: It's actually really hard to observe life without killing it, right?

MOLLY BLOOM: But William Harvey was very curious, and he noticed that this idea of where blood came from and how it worked in the body was old.

MAN: Yeah, this guy named Galen came up with it like a thousand years before I was even born. Are we really OK just being like, yeah, sure, Galen, blood just sloshes around. Well, I'm not.

MOLLY BLOOM: So one experiment he does involves a man's arm and a piece of fabric.

MAN: So get this, I tie the fabric tightly above the guy's elbow, and the vein pops out. Blood was stuck there and couldn't get out. And then I could feel the valves in the vein. And when I tried to push the blood around in the veins, it was obvious it could only flow in one direction.

MOLLY BLOOM: And this did not gel with what everyone else was thinking about the way blood worked. If it sloshed all around the body, it wouldn't be stuck in one spot like that.

MAN: And then there was the snake.

ALEXANDRA HUI: He cut a snake open and pinched the blood off above the snake's heart. So the snake is still alive. The heart is still bleeding. Blood is still flowing. And the heart starts to shrink and starts to get pale.

And it becomes clear to him that this is because it's empty, right? So he's pinched off the vein above the heart, and it's meant that the heart can't fill up with blood. And so it starts to look like a dead heart. Like it starts to really slow down and struggle.

And so then he lets go the blood, and it fills up the heart again. And then the heart's re-engaged and happy. And then he pinches off the aorta. And the heart becomes filled with blood. In doing this, he claims that he has demonstrated that the heart pumps the blood and it circulates through the body.

MAN: Boom. Major discovery right there. Take that, Galen.

ALEXANDRA HUI: That fundamentally changed the way people thought about bodies, thought about their own body, and thought about the heart. The heart suddenly becomes quite a bit more important. And this is based on this very careful set of experiments that he did.

MOLLY BLOOM: And, of course, the study of our circulatory systems didn't end there. Scientists after William Harvey kept doing experiments and learning more. The process of science is never done.

Scientists are still learning new things about the way our hearts beat.

KATIE: But sometimes experiments fail. And these failures can be just as important as the experiments that go perfectly according to plan.

MOLLY BLOOM: We're going to give an example of that in a minute. But first, we're going to do a very nonscientific test, a test of your listening skills. It's the shh.

GIRL: Mystery sound

MOLLY BLOOM: Here it is.


OK, any guesses?

KATIE: Well, it sort of sounds like paper being rustled or maybe even turned.

MOLLY BLOOM: And do you think what kind of paper that might be?

KATIE: It sounds like paper-- it's definitely not book paper. It doesn't sound like a book paper, but I'm not really sure.

MOLLY BLOOM: OK, well, we're going to hear that again a little later, so maybe you'll have a different guess. So keep mulling it over.

Want to send us your own mystery sound or maybe a drawing of a scientist at work?

KATIE: Or a question? Go to It's super easy.

MOLLY BLOOM: Just ask Draco who sent us this head-scratcher.

DRACO: How do snails get their shells?

KATIE: We'll unravel that mystery at the end of the show in the Moment of Um.

MOLLY BLOOM: Plus, we'll give a mega huge super loud full of love shout-out to the new members of the Brains Honor Roll. These are the kids who power our podcasts with ideas, art, and all-around awesomeness.

KATIE: So stick around with us.

MOLLY BLOOM: You're listening to Brains On. Here's a fact, I'm Molly, and this is Katie.

KATIE: Correct.

MOLLY BLOOM: OK, so we just heard how rigorous experiments led to people understanding that our blood actually circulates around our bodies. But failed experiments are important too. Cue dramatic music


MAN: It's time for the sad tale of the luminiferous ether.

MOLLY BLOOM: In the 1800s, scientists thought that this stuff called luminiferous ether was all around us. They thought, well, if sound waves move through air and waves in water move through water, light needed to move through something too. And that something was a substance they called the luminiferous ether.

ALEXANDRA HUI: It always sounds to me like the best band name, right? The subtle fluids and the luminiferous ether.

MOLLY BLOOM: Two people who wanted to prove that the luminiferous ether was all around us were Albert Michelson and Edward Morley. They thought they could do this by detecting what they called the ether wind. If there was luminiferous ether all around, you'd be able to detect the ether moving as our planet moved through it, kind of like feeling the wind moving past a car as it's driving.

MAN 1: We'll take it from here, Alex and Molly. Last we left the tale of Albert Michelson and Edward Morley in 1887, the duo were back in the United States after a frustrating trip to Germany.

MAN 2: Morley, old friend, it's good to be back in Ohio. Our trip to Germany was disappointing.

MAN 3: That's one word for it.

MAN 2: But I have not lost hope yet. This instrument this beautiful precise tool of detection that we built and designed ourselves will work this time. It will prove the existence of the luminiferous ether once and for all. We will detect the ether wind with this interferometer.

MAN 3: Hasa. I mean, this stuff is everywhere, right? It fills the space around us. It lets light travel through air, at least that's what everyone thinks.

MAN 2: I mean, we didn't detect it in Germany, but we have made the detector more precise. And this time, it will succeed. Our names will be listed alongside Sir Isaac Newton.

MAN 3: Cheers to that.

MAN 2: Commence the experiment.


MAN 1: That's the sound of time passing, of science happening.

MAN 2: Morley, old friend.

MAN 3: Yes, Michelson an old chum?

MAN 2: The result--

MAN 3: Yes?

MAN 2: It's not there.

MAN 3: The luminiferous ether?

MAN 2: It's not there.

MAN 3: But what is there?

MAN 1: What will their fellow scientists say? What will happen next? What is all around us if it's not luminiferous ether?

ALEXANDRA HUI: So when they repeated the experiment in Ohio, I think that at this point, people were paying attention, and I think there was an understanding that this was an elegant experiment. The design was great. The precision was top-notch. And if they weren't finding it, then yeah, maybe it wasn't there.

MOLLY BLOOM: So they had to admit they were wrong. It sort of blew up the way they and other physicists thought about the world. But scientists at the time weren't bitter or upset or sitting around saying, oh, no.

ALEXANDRA HUI: I think it was more of a like, oh, wow. Like look at the whole new set of possibilities this opened up. And in some ways, this freed physicists especially to think about the world differently.

MOLLY BLOOM: Soon enough, scientists came up with new ideas about how light traveled, and many of these ideas were confirmed by experiments. So even if a particular experiment fails, science is still working. And scientists are constantly replacing old ideas with new ones that help paint a more complete picture of how the world works.

CHILDREN: Brains On.

KATIE: We've heard some examples of how science worked in history. And now it's time to hear from a scientist working today.

MOLLY BLOOM: Or better yet, two scientists. Our pal, Sanden, spoke with a pair of researchers in a new and exciting field. He'll take it from here.

SANDEN TOTTEN: Even today, scientists are making discoveries that are changing how we see the world and ourselves.

REGINA JOICE CORDY: So I am Regina Joice Cordy.

MAUNA DASARI: OK, so my name is Mauna Dasari.

REGINA JOICE CORDY: And I am an assistant professor at Wake Forest University.

MAUNA DASARI: And I am a PhD candidate at the University of Notre Dame.

SANDEN TOTTEN: Regina and Mauna studied something called the microbiome.


MAUNA DASARI: So the microbiome is the word we use to talk about the world of microbes.

REGINA JOICE CORDY: Microbes which would be sort of like the bacteria and other very, very, very small organisms--

MAUNA DASARI: Tiny living creatures--

REGINA JOICE CORDY: You can't even see with the naked eye.

MAUNA DASARI: --that live all around us.

REGINA JOICE CORDY: They live on our skin, inside of our mouths, inside of our gut, so our stomach and the organs associated with digestion.

MAUNA DASARI: Most of them don't actually do anything to us, but many of them do help us.

SANDEN TOTTEN: For a long time, people mostly thought of bacteria as something that can spread from person-to-person and cause harm. They'd infect us and make us sick. Bleugh, no, thanks. But around 10 or so years ago, scientists started using a new tool called a DNA sequencer.

Now DNA is this complex molecule found in living things. And each living thing's DNA is unique. So this DNA sequencer can analyze all the different strands of DNA in a sample and tell you what life forms are in it.

So researchers used this tool to study the bodies of healthy people. And they found that these people weren't alone. They were full of trillions of these little bacteria called microbes. And a lot of these microbes weren't bad. They were actually helpful.


REGINA JOICE CORDY: They are very involved in our digestion.

MAUNA DASARi: Imagine you've eaten a burger. Your burger is going down your stomach. All of your stomach juices are all over it, but there are also all these tiny creatures on top of it.

REGINA JOICE CORDY: Bacteria and other very, very small microscopic organisms--

MAUNA DASARi: That are taking all of the pieces of the burger apart.

REGINA JOICE CORDY: And so they can actually help us to process the food that we're eating and extract nutrients from it.

MAUNA DASARi: Specific microbes that are taking the bun apart. Other microbes are taking apart the meat, as well as some that are just focused on the lettuce.

REGINA JOICE CORDY: And sometimes they can actually produce vitamins that are actually then soaked up by the human body. And altogether, this helps us have a more productive digestive system.

SANDEN TOTTEN: These microbes also seem to influence our mood, and some even fight off the bad bacteria to keep us healthy. Both Mauna and Regina do research to learn more about the microbiome. Regina has been gathering samples of different bacteria from Boston subways, which yeah, sounds totally yuck. But it turns out most of the samples had the same kind of microbes we'd find on our skin or in our homes. Nothing too alarming, which is a huge relief.

REGINA JOICE CORDY: I think it is a relief. I think that it's very difficult for people to separate these out. Like they can hear you say we found bacteria and, I think, immediately jump to thinking that it's something dangerous.

SANDEN TOTTEN: Mauna wants to know how this collection of microbes living in us changes as we age. But it's hard to study people because we take a really long time to age. So instead, she joined a project that studies baboons in Kenya.

MAUNA DASARI: So we follow about 500 baboons every day of the year, except Sundays and Christmas. If we see them, leave a sample. So if they poop, we'll identify it and then collect it.


SANDEN TOTTEN: Those poops are clues, stinky, important clues. You see, they contain all kinds of information about the microbes inside the baboons. Mauna can study the poop from a baboon when it was younger and then again later when it's old to see how the samples changed. Mauna and Regina will write about their findings and share them so other scientists can learn from the results and ask new questions.

Maybe the science will help us develop new medicines or find new ways to measure our health. Or maybe it'll help us discover something totally unexpected that will once again change how we see the world. If that happens, you can bet scientists like Mauna Dasari and Regina Joice Cordy will study that too.

MAN: Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On.

MOLLY BLOOM: OK. We've waited long enough. Let's find out the mystery behind the mystery sound. Before the big reveal, let's hear it one more time.


All right, any final guesses?

KATIE: It's definitely paper, but I'm not sure which kind.

MOLLY BLOOM: What kind of paper might it sound like? Just think about the kinds of paper in your life.

KATIE: Hmm. It sounds like copy paper or printer paper.

MOLLY BLOOM: Hmm, excellent guess. Well, here is the answer.

[? CHRISTINE HART: ?] That was the sound of pages being turned in a newspaper. My name is Christine [? Hart, ?] and I'm the managing production editor at the Minnesota Daily, which is the University of Minnesota's student run paper.

MOLLY BLOOM: So I have to ask you, Katie. Do you actually read a physical newspaper, or do you read it online?

KATIE: I read it online.

MOLLY BLOOM: So you're probably not super familiar with newspaper sound then?

KATIE: Yeah.

MOLLY BLOOM: Because like that newspaper paper is like a very specific kind of paper. And it does make a very loud sound when you turn the pages.

KATIE: Yep, pretty loud.

MOLLY BLOOM: [CHUCKLES] Christine's job is to decide the layout of the newspaper, so like which article goes on which page and what picture goes where.

[? CHRISTINE HART: ?] And then we usually rank the stories, like what should be in the front and what should be in the back, because the front and back are the pages that people tend to look at. And then from there, like how we design it to make it appealing is we put really big pictures because pictures draw the eye. And we also put more important things towards the top.

MOLLY BLOOM: Christine thinks of all the writing in the world, journalism is the most important. When it's done well, it helps people understand their world and make smart decisions.

[? CHRISTINE HART: ?] People really go into journalism because they have a passion to tell the truth and to give people the correct information and make change and understand what's going on.

MOLLY BLOOM: In our next episode, we're diving deep into the world of newspapers and journalism. How do journalists go about finding facts? And how do they do their jobs?

KATIE: I can see the headline now. Scrappy little podcast blows the lid off the world of news.



KATIE: There's not just one way to do science. But there is a quote to the work that the scientists do.

MOLLY BLOOM: They gather evidence to test ideas in a way that is replicable, precise, and objective.

KATIE: Science is constantly testing what we already know to find new knowledge.

MOLLY BLOOM: And sometimes this means old ways of thinking are replaced with new ones. That's it for this episode of Brains On.

KATIE: Brains On is produced by Molly Bloom, Marc Sanchez, and Sanden Totten.

MOLLY BLOOM: We had production help today from [? Netalee Brookstryker ?] and Emily Bright; engineering help from Veronica Rodriguez, [? Anthony Craven, ?] and Erik Stromstad. And many thanks to [? Megan Reddy, ?] [? Andrew Stevenson, ?] Anna Weggel, Jonathan Blakley, [? Eric Bringham, ?] Curtis Gilbert, [? Sam Chu, ?] and Max Nesterak.

KATIE: And Brains On is supported in part by funding from the National Science Foundation.

MOLLY BLOOM: We're a nonprofit public radio production. And donations from our listeners help us keep making new episodes. If you are interested in supporting Brains On, you can head to

KATIE: You can find more episodes of Brains On at, and you can find us on Twitter and Instagram at Brains_On.

MOLLY BLOOM: And if you have a question, mystery sound, drawing, or high five to share, head to

KATIE: Now, before we go, it's time for a Moment of Um


DRACO: My name is Draco, and I am from [INAUDIBLE] California. And my question is, how do snails get their shells?

MOLLY BLOOM: You know how we see like little videos of hermit crabs moving from one shell to another because they don't make their own? Snails, their shell, they make it themselves, and they're physically attached to it. And it gets bigger as they get bigger.

SKYLAR BAYER: My name Skylar Bayer, and I study reproduction in marine animals. And I live in Maine. There are lots of different kinds of snails. And a lot of snails often lay an egg sac, where the baby snails develop and they go through all these stages before they crawl away.

And when they crawl away, they have a little shell on them. Some species actually have them hatch after only a few days. They're in a larval stage. It's sort of a baby stage called a veliger.

And they don't quite look like a little snail. They don't have a full shell. It sort of looks like a glass slipper or bowl. And it's very thin.

They gather calcium carbonate from what they eat to make it harder. It really depends on the species and where they live and their habitat and what's sort of useful, what's their lifestyle choice. And that influences sort of how their shell grows and all of that.

MOLLY BLOOM: I was born ready to read this list of names. It's time for the Brains Honor Roll. These are the amazing listeners who share their intelligence and ideas with us. Here they are.


ROBOT: Brains Honor Roll. Bye Bye.

MOLLY BLOOM: We'll be back next week with more answers to your questions.

KATIE: Thanks for listening.

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