Speaker 1: Trapped on this little rock. We are desperate to extend
Speaker 1: our understanding beyond our cosmic jail cell without visiting any
Speaker 1: other planets or stars. We want to use our ingenuity
Speaker 1: to figure out how things work in the rest of
Speaker 1: the Solar System, in the heart of the Sun, or
Speaker 1: in distant stars. Until recently, we didn't know the answers
Speaker 1: to basic questions about the rest of the universe, questions
Speaker 1: like what elements is it made out of? Is the
Speaker 1: Sun made out of the same mixture of atoms as
Speaker 1: the Earth? What about the rest of the universe. Today
Speaker 1: we'll tell you the story of how we figured this
Speaker 1: all out. It features naked Greeks running down the street,
Speaker 1: Scottish people climbing mountains, and a clever young woman pushing
Speaker 1: back against the established but mistaken orthodoxy and not getting
Speaker 1: credit for it until recently. So we're going to do
Speaker 1: our bit to set the record straight and to show
Speaker 1: you how clever little apes can actually learn about the
Speaker 1: recipe for making a universe stuck in the confines of
Speaker 1: our little planet. Welcome to Daniel and Kelly's Extraordinary Elemental Universe.
Speaker 2: Hello, I'm Kelly water Smith. I study parasites and space,
Speaker 2: and I'm super excited to learn about another woman that
Speaker 2: we haven't heard anywhere near enough about today.
Speaker 1: Hi, I'm Daniel. I'm a particle physicist, and I study
Speaker 1: what the universe is made out of. But I'm also
Speaker 1: curious what I'm made out of.
Speaker 2: Oh, you know, biologists have been working on that for
Speaker 2: a while. What is your question in particular?
Speaker 1: Well, you know, people tell me that I am what
Speaker 1: I eat, which means I'm mostly dinner.
Speaker 2: I guess, Oh that's right, because you only eat dinner. Yeah, exactly,
Speaker 2: what did you have for dinner last night? What are you?
Speaker 2: What should I expect?
Speaker 1: Last night? We had a dinner party, actually, so we
Speaker 1: went a little fancy. We made miso honey chicken. We
Speaker 1: made asparagus and scallions with barrata. We made a very
Speaker 1: fancy salad. I made a lemon butter almond tart.
Speaker 2: Wow.
Speaker 1: Yeah it was good.
Speaker 2: That's amazing. Okay, But so the main part of the
Speaker 2: dish was chicken. So I'm gonna expect you to squawk
Speaker 2: about physics today.
Speaker 1: Oh and a couple of loaves of sour dough bread.
Speaker 2: Of course, Oh fantastic.
Speaker 1: You gotta have your carb. So yes, I'm chicken and
Speaker 1: bread today. I guess, all.
Speaker 2: Right, well, don't be sour about the information that we're
Speaker 2: going to be sharing. So my question for you today.
Speaker 2: So there was this recent result that maybe there's indirect
Speaker 2: evidence of life in the Solar System, and I was
Speaker 2: just wondering if you had to put a bet on it,
Speaker 2: let's say one hundred bucks, and you were betting, yes,
Speaker 2: there are microbes somewhere in our solar system, or no.
Speaker 1: In our solar system or in our galaxy.
Speaker 2: In our solar system, in our solar system, you know,
Speaker 2: in lava tubes on Mars, in the oceans of Enceladus.
Speaker 2: What do you think? What would you put the odds
Speaker 2: on for or whether or not there are microbes in
Speaker 2: our universe?
Speaker 1: Oh wow, put a number on something we can't possibly
Speaker 1: know and then risk money on it.
Speaker 2: It's not a ton of money, but no.
Speaker 1: I like that. I like framing these as gambling questions
Speaker 1: because it really makes you decide on like how much
Speaker 1: money you'd be willing to lose. I think I put
Speaker 1: the odds of there being alien microbes that is not
Speaker 1: derived from Earth and like you know, somehow kicked off
Speaker 1: via an asteroid somewhere in our solar system independently evolved
Speaker 1: unique apiogenesis somewhere, like, you know, one in a million. Maybe.
Speaker 1: I think it's probably pretty unlikely somewhere in the galaxy, though,
Speaker 1: I put it like ninety eight percent.
Speaker 2: Whoa, yeah, well, how many solar systems are in our galaxy.
Speaker 1: There's hundreds of billions of stars in the galaxy and
Speaker 1: so many planets around the stars, So I just feel
Speaker 1: like that number is so big.
Speaker 2: Yeah, those odds sound pretty good.
Speaker 1: Yeah, are you gonna take my bet?
Speaker 3: Ah?
Speaker 1: Ooh, the rubber hits the road people.
Speaker 2: That's right, that's right. Can you tell I came up
Speaker 2: with this question right before I hit record. I don't know,
Speaker 2: you know, it wouldn't absolutely shock me if they found
Speaker 2: microbes on Mars, given its wet past, or like evidence
Speaker 2: of past microbes or something, and so I, uh, yeah,
Speaker 2: I'll take your bet. I'll take the opposite.
Speaker 1: I wouldn't wait, does that mean I owe you one
Speaker 1: hundred million dollars if you find microbes on Mars?
Speaker 4: Oh?
Speaker 2: Oh uh no, let's just do let's forget odds. Let's
Speaker 2: just do one hundred bucks if you're right, one hundred
Speaker 2: bucks if I'm right.
Speaker 1: Oh, but then I'm betting against aliens. I don't want
Speaker 1: to ever bet against aliens. I'm rooting for aliens. I
Speaker 1: don't want to have a conflict of interest where I
Speaker 1: hope there aren't aliens. So then I get a hundred
Speaker 1: bucks from Kelly.
Speaker 2: I know this is difficult for you, but but we're
Speaker 2: just talking about microbes.
Speaker 1: Yeah, that's true.
Speaker 2: So the microbes that will teach you physics, you're not
Speaker 2: or sorry, the alien that will teach you physics, you're
Speaker 2: not betting against them.
Speaker 1: Okay, so all.
Speaker 2: Right, don't get sour on me here, Daniel. We're moving on. Okay.
Speaker 1: Today we're not talking about what's alive on Mars or
Speaker 1: in the oceans of Europa, or what Daniel aid for dinner.
Speaker 1: We're talking about what the whole universe is made out of,
Speaker 1: what building blocks, what elemental lego bricks are used to
Speaker 1: put our cosmos together.
Speaker 2: And how the heck did we figure that out, especially
Speaker 2: when the stuff is not on Earth?
Speaker 1: Yeah, exactly, and we've never left Earth asterisk. We really
Speaker 1: did go to the Moon, but kind of counts as
Speaker 1: part of Earth.
Speaker 2: Okay, but that definitely wasn't fake in it just to
Speaker 2: be clear, just to be c I did talk to
Speaker 2: a friend the other day who was like, and I
Speaker 2: know the moon landing wasn't real, and I was like,
Speaker 2: oh that was. Every once in a while you have
Speaker 2: one of those moments where you're like, that's I did.
Speaker 2: I didn't expect that. What do I say now?
Speaker 4: All right?
Speaker 2: Anyway, so let's talk to our audience, who almost certainly
Speaker 2: believes that we actually landed on the moon, and ask
Speaker 2: them how do we know what the universe is made of?
Speaker 1: If you would like to contribute your voice for future
Speaker 1: segments on the podcast, please don't be shy right to
Speaker 1: us to questions at Danielankelly dot org. We really really
Speaker 1: love hearing from you. I think we know what the
Speaker 1: universe is mde of? Do you just spectroscopy?
Speaker 4: I don't think we definitively know what it's made of,
Speaker 4: but we probably speculated.
Speaker 2: I think scientists can extrapolate from what's in the earth.
Speaker 1: Lensing likes spectrums and extrapolation from what's immediately around us.
Speaker 1: I don't think we do.
Speaker 3: We may live in a simulation, or that we may
Speaker 3: actually exist in a two dimensional universe projected onto a
Speaker 3: three D hologram. So when you get right down to it.
Speaker 3: The truth is nobody probably knows.
Speaker 4: Right different observational scientific techniques to try and understand the
Speaker 4: different components of it to the best we are able
Speaker 4: and make everything else up from there spectroscopy.
Speaker 1: Wait, do we know.
Speaker 2: That we are the universe?
Speaker 5: Yes, the universe is our way and out there. But
Speaker 5: if we can know the molecules that make up you
Speaker 5: and me and apples and mountains and porcupines and all
Speaker 5: the things we know of you're on Earth, that tells
Speaker 5: us what the universe is made of.
Speaker 1: To spectrocity and gravity.
Speaker 2: We know by spectroscopy, a lot of guessing followed by
Speaker 2: a lot of testing.
Speaker 1: The spectral analysis. We're not sure what dark matter is,
Speaker 1: and I seem to remember something about quantum foam, so
Speaker 1: maybe we don't really know.
Speaker 5: Data collective from ground and space based telescopes.
Speaker 3: I guess the bits that aren't dark matter either in
Speaker 3: midlight so we can look at the spectrum, or they
Speaker 3: have enough gravity to bend light.
Speaker 1: Easy.
Speaker 2: We take one piece of the universe, smash it into
Speaker 2: another piece of the universe and see what comes up.
Speaker 1: With a lot.
Speaker 2: I love the person who said do we know, because actually,
Speaker 2: if it's an episode you and I are doing. There's
Speaker 2: a pretty good chance the answer is we don't know,
Speaker 2: So throwing it back at us is a pretty good guess.
Speaker 1: Yeah, that is a great answer. I also like the
Speaker 1: answers that frame the question much more broadly. When I
Speaker 1: wrote this, I was thinking about what elements the universe
Speaker 1: is made out of, like the atomic matter that you
Speaker 1: know makes up the sun and the stars, and the
Speaker 1: gas and the dust and the wolverines and the ferrets
Speaker 1: and all that kind of stuff. I wasn't yes, exactly,
Speaker 1: I wasn't thinking more broadly, like dark matter, dark energy. So, yeah,
Speaker 1: these are good answers.
Speaker 2: Your question was underspecified.
Speaker 1: It was yes, I should have said, how do we
Speaker 1: know what elements the universe is made out of?
Speaker 2: That's right, We still got some fantastic answers. So what
Speaker 2: let's start with how we figured out what elements the
Speaker 2: Earth is made out of? What tools do we use
Speaker 2: for that here?
Speaker 1: Yeah, the story of figuring out what the universe is
Speaker 1: made out of goes like, first, let's figure out what
Speaker 1: the stuff under our feet and what we are made
Speaker 1: out of, and then let's think about whether we can
Speaker 1: extrapolate that to the rest of the universe because unfortunately
Speaker 1: we still can't go visit most of the universe. So
Speaker 1: in terms of like lab science and like getting our
Speaker 1: fingers literally dirty, the Earth is the only place we
Speaker 1: have to explore. And it's really cool story how we
Speaker 1: figured out what the Earth is made out of it
Speaker 1: because even though it's under our feet, we can't go
Speaker 1: like explore very deep. We haven't drilled very far into
Speaker 1: the earth, so a lot of it is still indirect
Speaker 1: evidence that we put together by clever humans figuring out
Speaker 1: ways to basically see what's inaccessible.
Speaker 2: Well not only getting to the center of the Earth,
Speaker 2: but just being able to like pick up a handful
Speaker 2: of dirt and being like, what kind of elements are
Speaker 2: in this handful of dirt. That's amazing to.
Speaker 1: Me as well exactly, and this requires a lot of
Speaker 1: you know, chemistry, understanding what elements were there and their
Speaker 1: properties and their mixture, and so early on in the
Speaker 1: last few hundred years, when people are trying to figure out, like, hey,
Speaker 1: what is the Earth made out of they're basically three
Speaker 1: big questions that were asking. One is like, what is
Speaker 1: the density of the earth? Can we figure that out?
Speaker 1: Because if we know the density of the Earth. We
Speaker 1: know a lot about what it could be made out
Speaker 1: of and what it couldn't. Like if you measure the
Speaker 1: density of the earth and you discover, oh, it has
Speaker 1: the density of whipped then you know it's not mostly ironed, right,
Speaker 1: Whereas if you measure the density the earth and it's
Speaker 1: like bang on nickel, then you're like, wow, it's probably
Speaker 1: most any nickel. Right. And so measuring the density of
Speaker 1: the earth is an important question. But this isn't easy, right, Like,
Speaker 1: how do you measure the density of something? Well, here
Speaker 1: on Earth, You like put it in water and see
Speaker 1: if it floats, or you measure its mass and you
Speaker 1: measure its volume, right, the famous Eureka moment of figuring
Speaker 1: out whether the crown is made of gold by measuring
Speaker 1: its volume by dipping it in water, et cetera, et cetera.
Speaker 2: This is apparently not a particularly famous Eureka moment because
Speaker 2: I've never heard that story.
Speaker 1: Oh this is a really fun Mas story. Archimedes was
Speaker 1: asked to determine whether the king's crown was made of
Speaker 1: pure gold or not, so he said, well, I'll measure
Speaker 1: its density, because if it's density lines up with gold,
Speaker 1: then we know it's gold, and if it's got something
Speaker 1: else in it, it'll come out a different number. Measure
Speaker 1: the density requires them in the mass and the volume.
Speaker 1: Mass not so hard, Volume not so hard. If you
Speaker 1: have a simple object like a sphere or a cube,
Speaker 1: how do you measure very precisely the volume of a
Speaker 1: really complex shape like a crown turns out to be
Speaker 1: really challenging. So Archimedies is puzzling over this as he's
Speaker 1: slipping into the bath at the end of his day.
Speaker 1: And as he gets into the bath, he sees the
Speaker 1: water level rise, and he's like, oh, now, I understand
Speaker 1: how to measure the volume. You just dip it in
Speaker 1: water and you measure how much it rises. And the
Speaker 1: story goes, probably apocryphally, that he left out of the
Speaker 1: baths and naked down the streets of Siracuse or Syracuse,
Speaker 1: shouting eureka, eureka. And anyway, that's your famous ancient Greek
Speaker 1: nude story for the day.
Speaker 2: Amazing. We should have more of those, But okay, I
Speaker 2: hadn't heard that story. Thanks for sharing.
Speaker 1: But in the case of the earth, you can't just
Speaker 1: dip the earth in water, right, you know, we don't
Speaker 1: have like a bath of water that we could dip
Speaker 1: it in. So what we need to do is measure
Speaker 1: the gravitational pull of the Earth. Right, if you knew
Speaker 1: the total mass and the volume, then you would have
Speaker 1: the density and the volume is pretty straightforward because the
Speaker 1: Earth is a spear. So if you could figure out
Speaker 1: the mass, then you'd know the answer. But figuring out
Speaker 1: the mass is a little bit complicated because to do
Speaker 1: that you have to measure the pull of gravity, and
Speaker 1: to do that you have to know so the constant
Speaker 1: in the gravitational formula Newton's gravitational formula says that the
Speaker 1: pole of gravity depends on two masses and on this
Speaker 1: number in between them. And for a long time we
Speaker 1: didn't know very precisely that number. And so to get
Speaker 1: that number you need like two large known masses that
Speaker 1: you can measure their gravitational pole between them, so you
Speaker 1: can get that number, and then you can measure gravity
Speaker 1: in the Earth and finally figure out what is the
Speaker 1: mass of the Earth.
Speaker 2: That sounds complicated, and so how did they find two
Speaker 2: massive objects to do this with?
Speaker 1: Yeah, they have to be massive objects because gravity is
Speaker 1: super duper weak. Right, you can't measure the gravitational pole
Speaker 1: between like two pennies in your hand. There is a
Speaker 1: gravitational pole there, but it's unmeasurable, especially like one hundred
Speaker 1: two hundred years ago. So what they did is they
Speaker 1: found a mountain. There's this mountain in Scotland called she Holand,
Speaker 1: and in the seventeen seventies that decided this was a
Speaker 1: good candidate for measuring the gravitational constant because it's isolated
Speaker 1: from lots of other stuff. So it's like a single
Speaker 1: mountain on a plane, far away from other stuff, and
Speaker 1: it's kind of symmetrical. It's like not hard to measure
Speaker 1: its volume pretty accurately. It's not like the crown of
Speaker 1: the King of Syracuse, right, it's like kind of a
Speaker 1: simple shape.
Speaker 2: Okay, so there's one massive object.
Speaker 1: Yeah. So then they took a pendulum and they held
Speaker 1: it near the mountain and they measured weather deviated from
Speaker 1: straight down, and the deviation of the pendulum from straight
Speaker 1: down as you get closer and further from the mountain
Speaker 1: is a measure of the gravitational pull of the mountain
Speaker 1: on the pendulum. Right. So here you're like actually measuring
Speaker 1: gravity between two things, neither of which are the Earth
Speaker 1: that works, actually does work. This was the first measurement
Speaker 1: of the gravitational constant, and it required actually a lot
Speaker 1: of work by surveyors, like converting the shape of the
Speaker 1: mountain into prisms so they could calculate the volume very accurately.
Speaker 1: It was a huge project, and that allowed them to
Speaker 1: measure the gravitational constant and then calculate the density of
Speaker 1: the Earth. And they discovered that the day to the
Speaker 1: Earth is like almost twice the density of that mountain.
Speaker 2: So this technique sounds incredibly complicated. How close did they
Speaker 2: get to the value that we believe it is today?
Speaker 1: They're within twenty percent.
Speaker 2: Nice.
Speaker 1: Yeah, and that's pretty good, you know for dudes in
Speaker 1: silly hats with pendulums, you know, walking around mountains like
Speaker 1: these clever apes are figuring stuff out.
Speaker 2: Yeah, no, that's amazing.
Speaker 3: You know.
Speaker 2: I feel like if you took five biologists in our
Speaker 2: field clothes or whatever and you were like figure out
Speaker 2: the density of the Earth, I'd feel pretty good if
Speaker 2: we got within twenty percent. That's pretty solid.
Speaker 1: And that is really revealing at the time, because people
Speaker 1: had no idea what was inside the earth? Is it
Speaker 1: like a hall of core? The way like King Kong
Speaker 1: and Godzilla are fighting down there? Is it mostly made
Speaker 1: of water? People really just didn't know. And this in
Speaker 1: a single measurement tells you a lot about what the
Speaker 1: Earth could and couldn't be made out of. And then
Speaker 1: there's a really amazing history of the measurements of the
Speaker 1: gravitational constant, which got more and more precise. Eventually people
Speaker 1: used torsion experiments like balls hanging on strings that are
Speaker 1: very sensitive and measured their deflection as it got closer
Speaker 1: together Cavendish et cetera. There's a whole fun history there.
Speaker 1: People made these measurements very precisely to within less than
Speaker 1: one percent. So now we have a very accurate estimate
Speaker 1: of the Earth's density.
Speaker 2: That is incredible. Okay, so we have an estimate of
Speaker 2: the density, what did it lead us to believe? That
Speaker 2: most of the Earth is made of yees?
Speaker 1: So the density of the Earth is more dense than
Speaker 1: the mountain, which is a hint that there's like heavy
Speaker 1: stuff in there. Right, it can't just be rock. It's
Speaker 1: not water, right. Water is much less dense than the Earth,
Speaker 1: and so that suggests that there's a dense core, that
Speaker 1: there's something heavy in there. And we now know, of course,
Speaker 1: there's a lot of nickel and iron in the core
Speaker 1: of the Earth. And this was our first hint about
Speaker 1: what was down there.
Speaker 2: Not a giant open sphere with like dinosaurs hiding in it,
Speaker 2: because that would have been cooler, Not.
Speaker 1: A vast chasm filled with swarming parasites, for example. For
Speaker 1: most people, that's a nightmare. For you, that's heaven.
Speaker 2: Now, I'm so bummed out to know that this is
Speaker 2: the Earth I exist on, but it could have been
Speaker 2: so much better.
Speaker 1: And people attack this question of what is the Earth
Speaker 1: made at of? From other angles. We have density, but
Speaker 1: the next angle was age. People were trying to estimate,
Speaker 1: like how old is the Earth, because understanding how old
Speaker 1: the Earth is gives you clues about how it's formed
Speaker 1: and therefore what it's made out of. And we already
Speaker 1: knew at this point a couple hundred years ago that
Speaker 1: the Earth was probably pretty old. And the biggest clue
Speaker 1: there was like Darwin, Darwin should us that life took
Speaker 1: a while to come together, you know, this process of
Speaker 1: evolution was slow, so we had a sense that the
Speaker 1: Earth was like cosmically old, not thousands of years, but
Speaker 1: people didn't really know is that like millions, hundreds of millions, billions,
Speaker 1: even it was still an open question a couple hundred
Speaker 1: years ago.
Speaker 2: Now, I love when Darwin gets credit for stuff, but
Speaker 2: I don't actually know that he should get credit for
Speaker 2: showing us that life was ancient. I mean he was.
Speaker 2: He came up with the theory of natural selection to
Speaker 2: explain how like one form sort of morphs into another.
Speaker 2: But I think there were geologists already working on this
Speaker 2: question and finding fossils and postulating Earth has been around
Speaker 2: for a long time and stuff has been gone. But anyway,
Speaker 2: Darwin awesome. Maybe he just got some credit for something
Speaker 2: he didn't deserve, but biologist getting credit for stuff is
Speaker 2: always awesome, So let's move on.
Speaker 1: Yeah, that's fair, And I'm about to give some credit
Speaker 1: to some chemists to hold onto your hats.
Speaker 2: Oh oh boy, I'm gonna get sour.
Speaker 1: People were wondering, like, how long would it take the
Speaker 1: Earth to cool if you have a like a ball
Speaker 1: of molten stuff sitting in space, how quickly does it
Speaker 1: form a crust that you can like walk around on.
Speaker 1: And Lord Kelvin of you know, Kelvin temperature trying to
Speaker 1: use this to calculate an approximate age for the Earth.
Speaker 1: He was thinking, like, you have a big ball of
Speaker 1: lava basically or magma in space, how quickly can you
Speaker 1: form a crust? And he ignored a bunch of stuff
Speaker 1: like he didn't understand that there was convection inside the
Speaker 1: Earth that hot stuff rises, and so you keep getting
Speaker 1: this like refresher of hot stuff from the core up
Speaker 1: to the surface. He also didn't know about radioactive decay,
Speaker 1: which helps heat the Earth, because he didn't know about
Speaker 1: radiation and quantum mechanics and all that stuff. Nobody had
Speaker 1: discovered that yet. So in Kelvin's calculation, he missed a
Speaker 1: lot of the pieces there, and he came up with
Speaker 1: a range of like twenty to four hundred million years,
Speaker 1: which is like low by more than a factor of
Speaker 1: ten because of these pieces he missed. But you know,
Speaker 1: he's sort of getting up there into the right ballpark.
Speaker 2: Yeah. And so at the time was the predominant view,
Speaker 2: the Christian view, that the Earth was like what two
Speaker 2: or five thousand years old or something. I think postulating
Speaker 2: millions of years could have really like put you in
Speaker 2: the crosshairs. But how common was the idea that it
Speaker 2: was just a couple thousand years old at that point.
Speaker 1: I think that most educated and scientific people didn't accept
Speaker 1: the young Earth hypothesis. Even back then, there was a sense,
Speaker 1: as you said, from geology that things were taking a
Speaker 1: long time. But then people were trying to make a
Speaker 1: specific They're like, can we get an actual number? And
Speaker 1: so I love when people in history are like, well,
Speaker 1: let's try to sit down and get a calculation of this,
Speaker 1: and you know they're wildly off, but getting that first
Speaker 1: estimate is a big step forward, and then you can
Speaker 1: refine it and think about what you're missing, And like,
Speaker 1: this is the process of science, right, First do the
Speaker 1: dumbest thing and then improve it. It's innerative, right.
Speaker 2: I feel like that's kind of where we are with
Speaker 2: the Drake equation, Like we're starting to hone in on
Speaker 2: the things that matter, and exercises like this help you
Speaker 2: think through stuff.
Speaker 1: Yeah, exactly. And now, of course we know a lot
Speaker 1: more precisely how old the Earth.
Speaker 2: Is, and when we get back from the break, we're
Speaker 2: going to hear all about that, all right. So Dan
Speaker 2: was just telling us that Kelvin was thinking about how
Speaker 2: long it would take a molten earth to cool to
Speaker 2: get our initial estimates for the age of the Earth,
Speaker 2: and we ended up with somewhere between twenty and four
Speaker 2: hundred million years. What was the next step that we
Speaker 2: took to get more accurate.
Speaker 1: More accurate understanding the age of the Earth, which again
Speaker 1: helps you understand what it's made out of. It came
Speaker 1: in this century when we understood that rocks have little
Speaker 1: clocks in them, and you can use that to figure
Speaker 1: out when the rock cooled, so you can figure out
Speaker 1: like when something was formed, and these clocks actually depend
Speaker 1: on quantum mechanics. There are these little crystals called zircon
Speaker 1: crystals that help you understand how old a.
Speaker 2: Rock is, and what is it about the zircon crystals
Speaker 2: and why isn't there a watch company called Zircon.
Speaker 1: Zircon are really weird little crystals that hate lead, like
Speaker 1: they will not allow lead to form within the crystal,
Speaker 1: but they will take uranium. So when you get a
Speaker 1: zircon crystal freshly formed, it has no lead in it,
Speaker 1: but it does have uranium in it, and then uranium
Speaker 1: while it's inside the crystal decays naturally into lead at
Speaker 1: a rate we know. So if you pick up a
Speaker 1: random zircon crystal and it has no lead in it.
Speaker 1: You know, this thing is zero years old. It's a
Speaker 1: baby crystal. If you pick up a zircon crystal and
Speaker 1: it's got no uranium and it's pure lead, you're like, wow,
Speaker 1: this thing is old because uranium is slow at decaying.
Speaker 1: So every zircon crystal is like a little clock that
Speaker 1: tells you how long it's been since it's formed.
Speaker 2: That's amazing.
Speaker 1: And there's a whole incredible story about a Chemisty Patterson,
Speaker 1: who figured this out and then started measuring the lead
Speaker 1: and stuff. And he's actually the guy who discovered, oh
Speaker 1: my gosh, this lead everywhere in our environment because of
Speaker 1: lead in gasoline, and he led the crusade to get
Speaker 1: lead out of gasoline because he was realizing, wow, we
Speaker 1: have poisoned our environment. He was trying to make a
Speaker 1: clean room to measure these things really precisely, and he
Speaker 1: just could not get a lead free environment. Wow. And
Speaker 1: so anyway, another chemist who saved us all.
Speaker 2: When it's so hard to know, like what study you're
Speaker 2: doing is going to be the thing that gives you
Speaker 2: important information for humans, like what sort of off ramps
Speaker 2: you're going to end up on?
Speaker 1: And so another argument for funding basic science people. But
Speaker 1: you never know what you're going to discuss important and
Speaker 1: so because of his work, we discovered that the Earth
Speaker 1: is like four and a half billion years old, meaning
Speaker 1: that the oldest rocks we have cooled around four and
Speaker 1: a half billion years ago.
Speaker 2: Oh my gosh. And that's pretty close to our current estimate,
Speaker 2: isn't it.
Speaker 1: Yeah, yeah, exactly.
Speaker 2: That's amazing.
Speaker 1: And so now understanding that the Earth is really old
Speaker 1: gives you more information to figure out the puzzle of like, well,
Speaker 1: what's it made out of? Because you want to understand
Speaker 1: like how old is the Earth, how quickly did it cool? Well,
Speaker 1: to know that you have to know like where's the
Speaker 1: heat coming from? Where are the layers inside the earth?
Speaker 1: You need a complete model for where stuff is within
Speaker 1: the earth, and that's why you need this last piece.
Speaker 1: So we have the age, we have the density. Next
Speaker 1: thing we need is the structure of the earth to
Speaker 1: know like how a stuff organized within the earth. And
Speaker 1: that's where seismology comes in to give us that last piece.
Speaker 2: Oh so we're getting away from chemistry, whew. Back to
Speaker 2: the rock people.
Speaker 1: Of seismology, of course, it's a study of earthquakes and
Speaker 1: earthquakes are cool. I mean, they're devastating and tragic, but
Speaker 1: they also do something really useful, which is that they
Speaker 1: ring the Earth like a bell. And so when there's
Speaker 1: an earthquake, these seismic waves pass through the Earth and
Speaker 1: they give you a glimp as to what's going on
Speaker 1: inside the Earth because these waves bounce off of like interfaces.
Speaker 1: If the whole Earth was just like one solid rock,
Speaker 1: then the waves would travel smoothly through it. But if
Speaker 1: there's an interface where you go from like one kind
Speaker 1: of rock to another, or you go from like nickel
Speaker 1: to iron, or liquid to not liquid, then the waves
Speaker 1: bounce back at that surface and you create complicated patterns.
Speaker 1: And so by reading the waves that reflect on the surface,
Speaker 1: you can reconstruct what was going on inside the Earth.
Speaker 1: It's sort of like a sonogram, right, or an ultrasound.
Speaker 2: That that is absolutely amazing. And just like parents like
Speaker 2: to brag about their kids, I like to brag about
Speaker 2: the human species sometimes, and just note that we've measured
Speaker 2: Mars quakes and it is just amazing to me that
Speaker 2: we've been able to like get equipment there that could
Speaker 2: then measure this happening on another planet in our solar system.
Speaker 2: So anyway, okay, amazing, all right, so now you can
Speaker 2: you can do this. And so did we know at
Speaker 2: the time enough to figure out so like you know,
Speaker 2: if you hit water and you had been going through nickel,
Speaker 2: you're like, oh, some thing is different. How much work
Speaker 2: did we have to do to understand what we were seeing?
Speaker 2: Like it seems like there's a big difference between saying
Speaker 2: something changed or something changed and I understand what that means.
Speaker 1: Yeah, the crucial thing there is having enough instrumented points,
Speaker 1: like you need to reconstruct these waves all across the Earth,
Speaker 1: because like a wave from an earthquake in California will
Speaker 1: propagate down into the Earth and reflect back, but doesn't
Speaker 1: come straight back to California and like goes to Japan
Speaker 1: or Hawaii or somewhere else, and it also continues through
Speaker 1: the Earth, and the different parts of the wave is
Speaker 1: like s waves and pea waves, and different frequencies reflect
Speaker 1: at different rates. And so what you really need to
Speaker 1: do is measure all the different frequencies as many places
Speaker 1: as you can around the Earth to get this complete picture.
Speaker 1: So that's what's crucial is having this like global network
Speaker 1: of seismic grass and yeah, on Mars they have a
Speaker 1: few of these, but wow, if they had more, they
Speaker 1: could really get pictures of these marsquakes and understand what's
Speaker 1: going on inside the Martian core, which is a whole
Speaker 1: other fascinating question about like whether there is still motion
Speaker 1: inside the core or whether it's totally frozen. And of
Speaker 1: course that tells us a lot about like the history
Speaker 1: of Mars and maybe did it have a magnetic field
Speaker 1: and could it protect life from cosmic radiation? But anyway,
Speaker 1: that's off track. Coming back to Earth. We now have
Speaker 1: an idea of what the structure of the Earth is,
Speaker 1: where the density of the Earth is, and how long
Speaker 1: it's been cooling, and altogether that gives us a model
Speaker 1: for what's going on inside the Earth without drilling down
Speaker 1: and going to visit. This is enough information to constrain
Speaker 1: our model and tell us what it has to be
Speaker 1: made out of, each of the layers and their composition.
Speaker 2: And so this is how we figured out that the
Speaker 2: core is mostly nickel and lead, not lead iron.
Speaker 1: Nickel and iron and iron got it. And so it
Speaker 1: turns out that the Earth is like thirty two percent
Speaker 1: iron thirty percent oxygen, which blows my mind. Most of
Speaker 1: it's like absorbed into rock. Fifteen percent silicon, fourteen percent magnesium,
Speaker 1: three percent sulfur, two percent nickel, and the rest of
Speaker 1: a lot of exciting trace elements. But that's the majority
Speaker 1: of what the Earth is made out of.
Speaker 2: Well, okay, so that's not a lot of nickel, So
Speaker 2: with mostly iron and oxygen.
Speaker 1: Mostly iron and oxygen, huh, yeah, exactly. There's a lot
Speaker 1: of oxygen in the Earth because rocks gobble up oxygen.
Speaker 1: Like in the early days of the Earth, when you
Speaker 1: be produced oxygen in the atmosphere, most of it was
Speaker 1: just absorbed by rocks. You have to like satisfy all
Speaker 1: the rocks before you could leave oxygen in the atmosphere
Speaker 1: for life.
Speaker 2: I'm glad there was some leftover for us.
Speaker 1: Yeah, because oxygen is so reactive. So that gives us
Speaker 1: a sense for what our scoop of the universe is
Speaker 1: made out of, right, iron, oxygen, silicon, magnesium. But then
Speaker 1: of course we're wondering, like what's the rest of the
Speaker 1: universe made out of? Is it the same? Is it different?
Speaker 1: What's the Sun made out of? And this is a
Speaker 1: question people had for a long time, like what is
Speaker 1: the Sun made out of how does it work, what's
Speaker 1: going on inside of it, and what fuels it?
Speaker 2: Yeah, because I think all of the techniques that we've
Speaker 2: talked about require you to be on the surface of
Speaker 2: that planet to collect the data, so you probably need
Speaker 2: a whole different set of tools to figure out what's
Speaker 2: happening on the Sun.
Speaker 1: Right, Yeah, exactly, And of course we can't go visit
Speaker 1: the Sun. We had the Parker Solar Probe, which came
Speaker 1: close to the Sun, but of course didn't go into
Speaker 1: the Sun. And for a long time we were trying
Speaker 1: to figure this out, of course, just from Earth and
Speaker 1: trying to understand what it could be made out of.
Speaker 1: And we can know some things without going to visit
Speaker 1: the Sun. Right. We can get a sense of the
Speaker 1: mass of the Sun if we know the gravitational constant
Speaker 1: and we know Earth's mass, and then we can calculate
Speaker 1: from the Earth's orbit how strong the Sun's gravity has
Speaker 1: to be to keep us in orbit. So already we
Speaker 1: know the Sun's mass, right, which gives us a lot
Speaker 1: of clues, but we don't know much about the density
Speaker 1: and what's going on inside there.
Speaker 2: Or the age. Right. We decided we needed to know
Speaker 2: age too, Yeah.
Speaker 1: And another crucial hint is while the Sun is very bright,
Speaker 1: so something going on inside the Sun producing that energy,
Speaker 1: and it's like an incredible amount of energy. I don't
Speaker 1: think people really appreciate how much energy is being put
Speaker 1: out by the Sun, Like we capture the tiniest, tiniest
Speaker 1: little fraction of it. But the Sun's total power outage
Speaker 1: is four times ten to the twenty six watts. Wow,
Speaker 1: which is like ten quadrillion times the amount of power
Speaker 1: released by the most energetic power plants ever constructed on Earth. Wow,
Speaker 1: it's just we are sipping from an ocean of energy here.
Speaker 1: That's just like being blasted out into space.
Speaker 2: And it powers our whole planet.
Speaker 1: It really does. And people wondered for a long time
Speaker 1: like what's producing all that energy? How long has the
Speaker 1: Sun been burning? They're wondering like is there something up
Speaker 1: there that's on fire? And that of course is a
Speaker 1: clue to what the Sun might be made out of.
Speaker 1: People were wondering like is it made at the same
Speaker 1: stuff as the Earth somehow? Is it made out of
Speaker 1: something different? So re enter Lord Kelvin, King of approximate
Speaker 1: initial terrible estimates of what the universe is.
Speaker 2: Made out of would I. I guess I'd be happy
Speaker 2: if I was known for anything, but I do feel
Speaker 2: like I wouldn't really want to be known for that
Speaker 2: in particular.
Speaker 1: No, I love that situation, like getting the first bited
Speaker 1: some apples, some fascinating question nobody's tackled. Those are the
Speaker 1: funnest ones I'm jealous of, Like the Greeks and the
Speaker 1: Sumerians and the ancient Chinese and the Mayans who got
Speaker 1: to think about these questions that nobody had worked on before, right,
Speaker 1: like the answer could have been anything anyway. I think
Speaker 1: that's super exciting.
Speaker 2: One of my favorite stories along this line is there
Speaker 2: was a guy who studied vaccines. His name was Sir
Speaker 2: Wright w R I g h T. And he every
Speaker 2: time got something important incorrect, and he ended up becoming
Speaker 2: known as Sir not quite right and all right anyway,
Speaker 2: tangent complete. Where were we?
Speaker 1: So? Lord Kelvin is trying to understand what's the sun
Speaker 1: man out of And first he thought, well, what if
Speaker 1: it's just like fuel. You know, we have fire here
Speaker 1: on Earth. If the Sun is a huge ball of
Speaker 1: fuel that's chemically burning, could that explain what we're seeing,
Speaker 1: you know? And that would tell you like, oh, maybe
Speaker 1: the Sun is a huge ball of gasoline basically or
Speaker 1: a curacy no runout. So if you do the calculation,
Speaker 1: giving your knowledge the mass of the sun, chemical burning
Speaker 1: can only produce that much power for like tens of
Speaker 1: thousands of years, not for billions of years. Why because
Speaker 1: chemical burning is very inefficient, like most of the energy
Speaker 1: in mass is not released when you just like change
Speaker 1: the chemical state from one to another. Whereas you know,
Speaker 1: fusion is what's happening inside the Sun, and that's much
Speaker 1: more efficient, much more effective release of energy. You get
Speaker 1: a lot more energy out. And so if you want
Speaker 1: to produce all the energy that the Sun is producing
Speaker 1: and do it for billions of years, you can't rely
Speaker 1: on like burning kerosene or some similar chemical process because
Speaker 1: there just isn't enough mass in the Sun to keep
Speaker 1: that going for billions of years.
Speaker 2: All right, It's not logs on a fire. So how
Speaker 2: do they figure out what it was?
Speaker 1: Well, people went down other rabbit holes also, which is
Speaker 1: really fun. They were thinking, maybe the Sun isn't limited
Speaker 1: to its current mass. Maybe this is some source of mass?
Speaker 1: Is it like gobbling up stuff from the Solar system?
Speaker 1: I mean early days you can think of all sorts
Speaker 1: of crazy ideas, right, Yeah, but that was ruled out
Speaker 1: pretty quickly because it would require an enormous amount of mass,
Speaker 1: Like you'd need a sun to refuel the Sun every
Speaker 1: ten thousand years, so it's like the Sun is not
Speaker 1: eating other stars every day. That would leave a huge
Speaker 1: imprint on the orbits of planets and stuff like that,
Speaker 1: so that was ruled out. Another thought people had is
Speaker 1: maybe the Sun is like contracting gravitationally and converting that
Speaker 1: gravitational potential energy somehow into heat. And this is sort
Speaker 1: of on the right track, but if you don't understand fusion,
Speaker 1: you don't have the final piece there. And this would
Speaker 1: only few the star for like tens of millions of years.
Speaker 1: And this is actually what's happening to neutron stars and
Speaker 1: white dwarves that are not undergoing fusion. They're just like
Speaker 1: being compressed and kept hot by gravity.
Speaker 2: Was this Kelvin's idea? All these because it matches up
Speaker 2: with his other All of these were Kelvins.
Speaker 1: These are Calvin's ideas. Yeah, this is Kelvin, like, you know,
Speaker 1: smoking whatever he was smoking and thinking about the universe
Speaker 1: and coming up with dumbers Okay, I love it. I'm
Speaker 1: a fan of Kelvin.
Speaker 2: Yeah, he sounds like a fun guy, and I think
Speaker 2: it would have been fun to read your theories about
Speaker 2: this kind of stuff. And then I could have called
Speaker 2: you not quite rights.
Speaker 1: In, Oh nice, Daniel wrongs and Daniel first a terrible approximation.
Speaker 2: Of the answer that doesn't roll off the tone quite
Speaker 2: as nicely. But okay, what else did Calvin think?
Speaker 1: So that's where the mystery stood until around the early
Speaker 1: nineteen hundreds, And at that point people sort of naturally
Speaker 1: assumed that the Sun must be made of the same
Speaker 1: stuff as the Earth. They were like, hey, the solar
Speaker 1: system comes together, stuff is formed. Why wouldn't the Sun
Speaker 1: be made of the same stuff as the Earth? And
Speaker 1: you know, I think this goes a long way to
Speaker 1: pointing out how often we accept ideas in science because
Speaker 1: they make sense to us without really interrogating them. You know,
Speaker 1: what seems natural doesn't always get as many questions as
Speaker 1: what seems weird, And so later on, one hundred years later,
Speaker 1: when something else seems natural, we might wonder like, huh,
Speaker 1: how could they accept that? But at the time it
Speaker 1: was the most natural explanation, And now is the time
Speaker 1: to enter the major villain of this story, Henry Russell.
Speaker 1: In nineteen fourteen, he wrote, if the Earth's crust should
Speaker 1: be raised to the temperature of the Sun's atmosphere, it
Speaker 1: would give a very similar absorption spectrum. The spectrum of
Speaker 1: the Sun and other stars are similar, so it appears
Speaker 1: that the relative abundance of elements in the universe was
Speaker 1: like that in the Earth's crust. So he's saying the
Speaker 1: Sun is made out of the same stuff as the Earth,
Speaker 1: and if you heat it up the Earth it would
Speaker 1: glow just like the Sun.
Speaker 2: So that sounds wrong, but not villainous. What are we
Speaker 2: going to get to more? Or do you just really
Speaker 2: thought this idea was dumb.
Speaker 1: That's not his villainy, that was just foreshadowing.
Speaker 2: Oh okay, let's take a break and when we come back,
Speaker 2: we'll find out what made Russell villainous. All right, Daniel,
Speaker 2: I'm on pins and needles. Let's get to the story
Speaker 2: of why Russell was such a villain.
Speaker 1: So Russell was on the right track and trying to
Speaker 1: understand what the Sun is made out of, and many
Speaker 1: of our listeners gave this answer. The answer is spectroscopy,
Speaker 1: Like if you can't go there. What can you do
Speaker 1: to understand what something is made out of? And it's
Speaker 1: similar to what you might do on Earth as you mentioned,
Speaker 1: like if you needed to know what is a scoop
Speaker 1: of dirt made out of, you might try to separate
Speaker 1: into components and then you might heat them up and
Speaker 1: look at the light that they emit. Because different atoms
Speaker 1: emit at different wavelengths. Right, every atom has different energy levels.
Speaker 1: The electrons can be on those energy levels, but not
Speaker 1: between them. If you heat it up, the electrons go
Speaker 1: up energy levels. If you let it cool down, the
Speaker 1: electrons go down energy levels and emit photons. The energy
Speaker 1: of those photons matches the energy difference between those energy
Speaker 1: levels and tells you what is the difference between those
Speaker 1: energy levels. And every atom has a different set of energies,
Speaker 1: so every atom has a different spectrum. So you take
Speaker 1: a gas of random stuff, you don't know what it is,
Speaker 1: you heat it up, you look at the energy levels.
Speaker 1: You can figure out what it's made out of and
Speaker 1: what the relative contributions are. You're like, oh, there's a
Speaker 1: little I see hydrogen in here, I see helium here,
Speaker 1: I see lithium or magnesium right, it's an amazing way
Speaker 1: to tell what Earth is made out of. So, in
Speaker 1: terms of the general approach to the listeners and the
Speaker 1: villain of today's episode, Henry Russell, are on the right track.
Speaker 1: The spectroscopy is the way to go.
Speaker 2: He didn't develop spectroscopy, right, he just applied it incorrectly.
Speaker 1: That's right. He didn't develop spectroscopy. And you notice in
Speaker 1: his quote he says if the Earth's crust should be raised,
Speaker 1: it would give a very similar absorption spectrum. And so
Speaker 1: he's sort of speculating here, right, And the problem is
Speaker 1: that this wasn't as easy as we describe it. There
Speaker 1: was an important complexifying factor here, which is ionization. And
Speaker 1: so for example, you might think, well, why don't they
Speaker 1: just look at the light from the Sun and you
Speaker 1: use that to figure out what the Sun is made of?
Speaker 1: Boom boom boom. Done right. Well, the problem is the
Speaker 1: atmosphere of the Sun is complicated, and there's one more
Speaker 1: factor we didn't describe, which is that the atmosphere is ionized.
Speaker 1: Like sometimes these gases in the Sun's atmosphere gets so
Speaker 1: much energy they lose electrons. It's not just like, oh,
Speaker 1: you've got oxygen and has all of its electrons and
Speaker 1: they're going up and down and emitting photons can tell
Speaker 1: it's oxygen. Sometimes those electrons are lost, right, and when
Speaker 1: an atom gets ionized, its energy levels shift a little bit.
Speaker 1: Because it's a big complicated thing, and so the spectrum
Speaker 1: you expect from a star depends on how many electrons
Speaker 1: are around those nuclei, which depends a little bit on
Speaker 1: the temperature of the gas. So it turns out to
Speaker 1: be kind of a complex problem.
Speaker 2: So does that mean that the spectroscopy results from the
Speaker 2: sun were wrong? And he didn't realize that, and that
Speaker 2: was the main problem.
Speaker 1: The spectroscopy results from the Sun. Nobody could understand yet.
Speaker 1: They were like, hmm, this is weird. We don't understand
Speaker 1: these lines. They look different from what we expect. But
Speaker 1: Russell was convinced anyway that it was made of the
Speaker 1: same stuff of the Earth. He believed that it was natural.
Speaker 1: To him. He was like, I'm sure this is just
Speaker 1: some detail. We'll figure this out. And so now enter
Speaker 1: the heroine of this episode. Yes, Cecilia Pain. Cecilia Pain
Speaker 1: is the one who solved this problem. She read a
Speaker 1: paper by a brilliant guy named Megnad Saha, who understood
Speaker 1: all the these ionization effects. He like calculated exactly what you
Speaker 1: should expect for various ionizations at various temperatures of all
Speaker 1: of the elements. He was just like, he wasn't thinking
Speaker 1: about the Sun. He was just like, Hey, chemistry is cool,
Speaker 1: and I want to understand energy levels and let's dig
Speaker 1: deep into this. And he totally nerded out about this.
Speaker 1: And Cecily Pain is like, oh, this is a solution
Speaker 1: to this huge problem that we have over in astrophysics
Speaker 1: of understanding what we should expect from the sun. So
Speaker 1: she put these two things together and she was able
Speaker 1: to interpret correctly the spectrum of light we're getting from
Speaker 1: the Sun and understand why it looked a little shifted
Speaker 1: and a little weird from what folks like Henry Russell expected.
Speaker 2: Amazing, and like note students, the importance of reading widely.
Speaker 2: I think there are so many connections that you make
Speaker 2: that you might not be expecting.
Speaker 1: Yeah, exactly, And so this is a huge breakthrough and like,
Speaker 1: finally we could understand what the sun is made out of.
Speaker 1: And the result was a huge surprise, especially to folks
Speaker 1: like Pain. Number one, the sun is made out of
Speaker 1: the same stuff as the Earth, Like there's hydrogen in this, helium,
Speaker 1: this oxygen, iron, this nickel, this all the same stuff,
Speaker 1: but it comes in very different numbers. Like the relative
Speaker 1: abundances are very very different in the Sun. Basically the
Speaker 1: Sun is mostly hydrogen and helium and everything else is there,
Speaker 1: but it's tiny, Like it's seventy four percent hydrogen, twenty
Speaker 1: five percent helium, and everything else is one percent.
Speaker 2: Wow. Yeah, all right, And so I'm just gonna guess,
Speaker 2: based on some other conversations we've had about women in science,
Speaker 2: that Russell isn't just the villain because he was wrong,
Speaker 2: but he probably did something to turf Pain's results. Am
Speaker 2: I right?
Speaker 1: Oh? Absolutely?
Speaker 2: Okay.
Speaker 1: So she was at Harvard and the director of the
Speaker 1: observatory was Russell, and Russell had the power at the
Speaker 1: time to veto any publication he wanted for whatever reason,
Speaker 1: including her thesis. Aw So he blocked her getting her
Speaker 1: PhD thesis unless she added the following caveat to her
Speaker 1: thesis quote. The outstanding discrepancy between the astrophysical and to
Speaker 1: rrestrial abundances are displayed for hydrogen and helium. The enormous
Speaker 1: abundance derived for these elements in the atmosphere is almost
Speaker 1: certainly not real.
Speaker 2: What he had her at a caveat that was like,
Speaker 2: but also, probably I'm wrong.
Speaker 1: Is all this amazing science is huge breakthrough and then
Speaker 1: he's like, I disagree with it, so probably this is BS.
Speaker 1: Don't believe these numbers.
Speaker 2: By the way, Oh my gosh. And what a coward
Speaker 2: that he did. Sounds like he didn't point out exactly
Speaker 2: where she had an error right, like because.
Speaker 1: He just couldn't accept it. He was like, no, the
Speaker 1: science says, so I don't see a mistake, but no,
Speaker 1: this flies in the face of what I believe, and
Speaker 1: so I'm gonna insist that you add this caveat to
Speaker 1: her thesis. Her advisor was a guy named Harlow Shapley
Speaker 1: and shapely ordered six hundred copies of her thesis and
Speaker 1: sent it to all the important astronomers in the world.
Speaker 2: Oh wow, okay, so he believed in her.
Speaker 1: He believed in her. Yet did he go through exactly.
Speaker 2: All six hundred copies and like cross out that line
Speaker 2: that she had to add.
Speaker 1: I don't know, but he knew this guy because Russell
Speaker 1: was also his PhD advisor. So I think they had
Speaker 1: a common experience there. But it gets even worse because
Speaker 1: even though Russell said no, this isn't true, this can't
Speaker 1: be true, a few years later, when the scientific tides
Speaker 1: turned and everybody accepted this, he took credit for this discovery. No, yes, exactly,
Speaker 1: And so in most historical records until recently, people gave
Speaker 1: Henry Russell credit for a discovery of what the sun
Speaker 1: is made out of, which is like such a tragedy.
Speaker 2: No it is, I agree, it's exactly.
Speaker 1: He's a total villain. So only four years after calling
Speaker 1: it impossible, you find him in the literature taking credit
Speaker 1: for this discovery. So it's a real shame.
Speaker 2: It isn't real. Okay, So then how did we rediscover
Speaker 2: Cecilia Paine?
Speaker 3: Then?
Speaker 1: Yeah, that's an important point. Cecia Paine ended up getting
Speaker 1: her PhD in astronomy, only the second PhD in astronomy
Speaker 1: ever by a woman at Harvard WOW. And initially she
Speaker 1: was barred from becoming a professor at Harvard because she
Speaker 1: was a woman, so she did a lot of less prestigious,
Speaker 1: lower paid research job, but she ended up becoming the
Speaker 1: first female tenured professor at Harvard WOW, and the first
Speaker 1: female chair of a department at Harvard.
Speaker 4: Wow.
Speaker 1: So you know, things changed and she ended up having
Speaker 1: a good career in astrophysics. And then later people digging
Speaker 1: into the record corrected it, and so, for example, there
Speaker 1: is an essay by Otto Struve who called it quote
Speaker 1: undoubtedly the most brilliant Pahd thesis ever written in astronomy.
Speaker 2: Wow.
Speaker 1: Wow, that's forty years later. She went forty years before
Speaker 1: really getting the recognition.
Speaker 2: Was she still alive, Yeah, she was.
Speaker 1: She died in seventy nine.
Speaker 2: I'm glad she got to see her work vindicated in
Speaker 2: her lifetime. That's amazing.
Speaker 1: Yeah. She ended up winning some prizes and was elected
Speaker 1: to the Royal Astronomical Society. The arc of justice is long,
Speaker 1: but it does point in the right direction, even into astronomy.
Speaker 2: I mean often, but not.
Speaker 1: Always eventually, I hope, yes. But to see it, pain
Speaker 1: taught us a lot about the nature of the universe, right.
Speaker 1: People thought for a long time that everything in the
Speaker 1: verse must be made out of the same stuff as
Speaker 1: the Earth, like that was a natural assumption to them.
Speaker 1: And now we know, of course that the Sun is
Speaker 1: mostly hydrogen and helium, and from our models of the
Speaker 1: formation of the solar system. It makes sense, right, Like
Speaker 1: the Sun is the center of gravity and most stuff
Speaker 1: flocks there and it pulls in all the gases in
Speaker 1: the inner Solar System, and the Earth did have more
Speaker 1: hydrogen helium early on, but because these are such light elements,
Speaker 1: they were blasted away by the Sun's radiation in the
Speaker 1: early part of the formation of the Solar System. So
Speaker 1: now we have a full and complex and nuanced understanding
Speaker 1: of the formation of the Solar System and the planets,
Speaker 1: and we can apply this knowledge to understanding other stars,
Speaker 1: like our star isn't the only star in the universe,
Speaker 1: and every star has its own unique pattern. We talked
Speaker 1: recently about why stars are different colors because they are
Speaker 1: made of different stuff, and their atmospheres has different stuff
Speaker 1: and they're different temperatures. And now with this model, with
Speaker 1: to see a pain's understanding, we can use this to
Speaker 1: understand what the rest of the universe is made out of.
Speaker 2: Wow, Okay, And so with these corrections we can now
Speaker 2: look at out into the universe and without even visiting it,
Speaker 2: we can know what different celestial bodies are made out of.
Speaker 1: Yeah, exactly. Thanks to Secila opinion and to Megna Saha,
Speaker 1: he is an Indian astrophysicist who figured out the ionization equations.
Speaker 1: His Saha ionization equation is super important for us to
Speaker 1: figure out the nature of the universe. And it's incredible
Speaker 1: that we can figure this out. I mean, think about
Speaker 1: all the little puzzles that people had to solve all
Speaker 1: the way down to like figuring out how massive the
Speaker 1: Earth is by measuring a mountain in Scotland. Like, all
Speaker 1: of these pieces were necessary and they all came together.
Speaker 1: And when you're solving a puzzle, often there's like a
Speaker 1: huge unanswered question that you don't even know how to begin.
Speaker 1: And if you're lucky, people have been working on that
Speaker 1: question for other reasons for one hundreds of years, making progress,
Speaker 1: hiking around mountains trying to figure it out, or just
Speaker 1: nerding out about the chemistry. But sometimes you're not so lucky.
Speaker 1: And that's why it's so important that we push in
Speaker 1: so many directions simultaneously, even though we don't know yet
Speaker 1: how they're going to be useful or what mysteries they
Speaker 1: might unlock. We need all of these tools so that
Speaker 1: in the future, clever people can come up with answers
Speaker 1: to huge questions like what is the universe?
Speaker 2: Made out of amen. By geeking out and by geeking
Speaker 2: out together, we can change the world.
Speaker 1: All right. Thanks very much for coming on this tour
Speaker 1: of how we figured out what elements of the universe
Speaker 1: is made out of diving deep into the earth and
Speaker 1: casting our minds all the way across the universe.
Speaker 2: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We
Speaker 2: would love to hear from you.
Speaker 1: We really would. We want to know what questions you
Speaker 1: have about this Extraordinary Universe.
Speaker 2: We want to know your thoughts on recent shows, suggestions
Speaker 2: for future shows. If you contact us, we will get
Speaker 2: back to you.
Speaker 1: We really mean it. We answer every message. Email us
Speaker 1: at Questions at Danielankelly.
Speaker 2: Dot org, or you can find us on social media.
Speaker 2: We have accounts on x, Instagram, Blue Sky and on
Speaker 2: all of those platforms. You can find us at D
Speaker 2: and K Universe.
Speaker 1: Don't be shy write to us.