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Speaker 1: Trapped on this little rock. We are desperate to extend

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Speaker 1: our understanding beyond our cosmic jail cell without visiting any

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Speaker 1: other planets or stars. We want to use our ingenuity

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Speaker 1: to figure out how things work in the rest of

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Speaker 1: the Solar System, in the heart of the Sun, or

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Speaker 1: in distant stars. Until recently, we didn't know the answers

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Speaker 1: to basic questions about the rest of the universe, questions

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Speaker 1: like what elements is it made out of? Is the

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Speaker 1: Sun made out of the same mixture of atoms as

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Speaker 1: the Earth? What about the rest of the universe. Today

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Speaker 1: we'll tell you the story of how we figured this

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Speaker 1: all out. It features naked Greeks running down the street,

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Speaker 1: Scottish people climbing mountains, and a clever young woman pushing

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Speaker 1: back against the established but mistaken orthodoxy and not getting

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Speaker 1: credit for it until recently. So we're going to do

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Speaker 1: our bit to set the record straight and to show

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Speaker 1: you how clever little apes can actually learn about the

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Speaker 1: recipe for making a universe stuck in the confines of

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Speaker 1: our little planet. Welcome to Daniel and Kelly's Extraordinary Elemental Universe.

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Speaker 2: Hello, I'm Kelly water Smith. I study parasites and space,

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Speaker 2: and I'm super excited to learn about another woman that

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Speaker 2: we haven't heard anywhere near enough about today.

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Speaker 1: Hi, I'm Daniel. I'm a particle physicist, and I study

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Speaker 1: what the universe is made out of. But I'm also

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Speaker 1: curious what I'm made out of.

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Speaker 2: Oh, you know, biologists have been working on that for

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Speaker 2: a while. What is your question in particular?

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Speaker 1: Well, you know, people tell me that I am what

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Speaker 1: I eat, which means I'm mostly dinner.

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Speaker 2: I guess, Oh that's right, because you only eat dinner. Yeah, exactly,

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Speaker 2: what did you have for dinner last night? What are you?

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Speaker 2: What should I expect?

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Speaker 1: Last night? We had a dinner party, actually, so we

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Speaker 1: went a little fancy. We made miso honey chicken. We

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Speaker 1: made asparagus and scallions with barrata. We made a very

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Speaker 1: fancy salad. I made a lemon butter almond tart.

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Speaker 2: Wow.

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Speaker 1: Yeah it was good.

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Speaker 2: That's amazing. Okay, But so the main part of the

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Speaker 2: dish was chicken. So I'm gonna expect you to squawk

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Speaker 2: about physics today.

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Speaker 1: Oh and a couple of loaves of sour dough bread.

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Speaker 2: Of course, Oh fantastic.

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Speaker 1: You gotta have your carb. So yes, I'm chicken and

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Speaker 1: bread today. I guess, all.

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Speaker 2: Right, well, don't be sour about the information that we're

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Speaker 2: going to be sharing. So my question for you today.

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Speaker 2: So there was this recent result that maybe there's indirect

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Speaker 2: evidence of life in the Solar System, and I was

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Speaker 2: just wondering if you had to put a bet on it,

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Speaker 2: let's say one hundred bucks, and you were betting, yes,

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Speaker 2: there are microbes somewhere in our solar system, or no.

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Speaker 1: In our solar system or in our galaxy.

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Speaker 2: In our solar system, in our solar system, you know,

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Speaker 2: in lava tubes on Mars, in the oceans of Enceladus.

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Speaker 2: What do you think? What would you put the odds

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Speaker 2: on for or whether or not there are microbes in

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Speaker 2: our universe?

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Speaker 1: Oh wow, put a number on something we can't possibly

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Speaker 1: know and then risk money on it.

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Speaker 2: It's not a ton of money, but no.

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Speaker 1: I like that. I like framing these as gambling questions

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Speaker 1: because it really makes you decide on like how much

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Speaker 1: money you'd be willing to lose. I think I put

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Speaker 1: the odds of there being alien microbes that is not

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Speaker 1: derived from Earth and like you know, somehow kicked off

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Speaker 1: via an asteroid somewhere in our solar system independently evolved

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Speaker 1: unique apiogenesis somewhere, like, you know, one in a million. Maybe.

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Speaker 1: I think it's probably pretty unlikely somewhere in the galaxy, though,

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Speaker 1: I put it like ninety eight percent.

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Speaker 2: Whoa, yeah, well, how many solar systems are in our galaxy.

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Speaker 1: There's hundreds of billions of stars in the galaxy and

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Speaker 1: so many planets around the stars, So I just feel

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Speaker 1: like that number is so big.

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Speaker 2: Yeah, those odds sound pretty good.

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Speaker 1: Yeah, are you gonna take my bet?

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Speaker 3: Ah?

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Speaker 1: Ooh, the rubber hits the road people.

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Speaker 2: That's right, that's right. Can you tell I came up

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Speaker 2: with this question right before I hit record. I don't know,

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Speaker 2: you know, it wouldn't absolutely shock me if they found

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Speaker 2: microbes on Mars, given its wet past, or like evidence

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Speaker 2: of past microbes or something, and so I, uh, yeah,

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Speaker 2: I'll take your bet. I'll take the opposite.

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Speaker 1: I wouldn't wait, does that mean I owe you one

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Speaker 1: hundred million dollars if you find microbes on Mars?

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Speaker 4: Oh?

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Speaker 2: Oh uh no, let's just do let's forget odds. Let's

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Speaker 2: just do one hundred bucks if you're right, one hundred

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Speaker 2: bucks if I'm right.

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Speaker 1: Oh, but then I'm betting against aliens. I don't want

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Speaker 1: to ever bet against aliens. I'm rooting for aliens. I

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Speaker 1: don't want to have a conflict of interest where I

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Speaker 1: hope there aren't aliens. So then I get a hundred

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Speaker 1: bucks from Kelly.

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Speaker 2: I know this is difficult for you, but but we're

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Speaker 2: just talking about microbes.

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Speaker 1: Yeah, that's true.

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Speaker 2: So the microbes that will teach you physics, you're not

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Speaker 2: or sorry, the alien that will teach you physics, you're

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Speaker 2: not betting against them.

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Speaker 1: Okay, so all.

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Speaker 2: Right, don't get sour on me here, Daniel. We're moving on. Okay.

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Speaker 1: Today we're not talking about what's alive on Mars or

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Speaker 1: in the oceans of Europa, or what Daniel aid for dinner.

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Speaker 1: We're talking about what the whole universe is made out of,

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Speaker 1: what building blocks, what elemental lego bricks are used to

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Speaker 1: put our cosmos together.

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Speaker 2: And how the heck did we figure that out, especially

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Speaker 2: when the stuff is not on Earth?

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Speaker 1: Yeah, exactly, and we've never left Earth asterisk. We really

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Speaker 1: did go to the Moon, but kind of counts as

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Speaker 1: part of Earth.

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Speaker 2: Okay, but that definitely wasn't fake in it just to

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Speaker 2: be clear, just to be c I did talk to

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Speaker 2: a friend the other day who was like, and I

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Speaker 2: know the moon landing wasn't real, and I was like,

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Speaker 2: oh that was. Every once in a while you have

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Speaker 2: one of those moments where you're like, that's I did.

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Speaker 2: I didn't expect that. What do I say now?

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Speaker 4: All right?

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Speaker 2: Anyway, so let's talk to our audience, who almost certainly

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Speaker 2: believes that we actually landed on the moon, and ask

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Speaker 2: them how do we know what the universe is made of?

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Speaker 1: If you would like to contribute your voice for future

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Speaker 1: segments on the podcast, please don't be shy right to

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Speaker 1: us to questions at Danielankelly dot org. We really really

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Speaker 1: love hearing from you. I think we know what the

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Speaker 1: universe is mde of? Do you just spectroscopy?

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Speaker 4: I don't think we definitively know what it's made of,

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Speaker 4: but we probably speculated.

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Speaker 2: I think scientists can extrapolate from what's in the earth.

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Speaker 1: Lensing likes spectrums and extrapolation from what's immediately around us.

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Speaker 1: I don't think we do.

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Speaker 3: We may live in a simulation, or that we may

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Speaker 3: actually exist in a two dimensional universe projected onto a

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Speaker 3: three D hologram. So when you get right down to it.

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Speaker 3: The truth is nobody probably knows.

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Speaker 4: Right different observational scientific techniques to try and understand the

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Speaker 4: different components of it to the best we are able

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Speaker 4: and make everything else up from there spectroscopy.

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Speaker 1: Wait, do we know.

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Speaker 2: That we are the universe?

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Speaker 5: Yes, the universe is our way and out there. But

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Speaker 5: if we can know the molecules that make up you

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Speaker 5: and me and apples and mountains and porcupines and all

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Speaker 5: the things we know of you're on Earth, that tells

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Speaker 5: us what the universe is made of.

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Speaker 1: To spectrocity and gravity.

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Speaker 2: We know by spectroscopy, a lot of guessing followed by

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Speaker 2: a lot of testing.

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Speaker 1: The spectral analysis. We're not sure what dark matter is,

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Speaker 1: and I seem to remember something about quantum foam, so

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Speaker 1: maybe we don't really know.

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Speaker 5: Data collective from ground and space based telescopes.

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Speaker 3: I guess the bits that aren't dark matter either in

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Speaker 3: midlight so we can look at the spectrum, or they

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Speaker 3: have enough gravity to bend light.

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Speaker 1: Easy.

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Speaker 2: We take one piece of the universe, smash it into

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Speaker 2: another piece of the universe and see what comes up.

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Speaker 1: With a lot.

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Speaker 2: I love the person who said do we know, because actually,

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Speaker 2: if it's an episode you and I are doing. There's

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Speaker 2: a pretty good chance the answer is we don't know,

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Speaker 2: So throwing it back at us is a pretty good guess.

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Speaker 1: Yeah, that is a great answer. I also like the

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Speaker 1: answers that frame the question much more broadly. When I

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Speaker 1: wrote this, I was thinking about what elements the universe

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Speaker 1: is made out of, like the atomic matter that you

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Speaker 1: know makes up the sun and the stars, and the

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Speaker 1: gas and the dust and the wolverines and the ferrets

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Speaker 1: and all that kind of stuff. I wasn't yes, exactly,

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Speaker 1: I wasn't thinking more broadly, like dark matter, dark energy. So, yeah,

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Speaker 1: these are good answers.

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Speaker 2: Your question was underspecified.

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Speaker 1: It was yes, I should have said, how do we

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Speaker 1: know what elements the universe is made out of?

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Speaker 2: That's right, We still got some fantastic answers. So what

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Speaker 2: let's start with how we figured out what elements the

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Speaker 2: Earth is made out of? What tools do we use

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Speaker 2: for that here?

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Speaker 1: Yeah, the story of figuring out what the universe is

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Speaker 1: made out of goes like, first, let's figure out what

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Speaker 1: the stuff under our feet and what we are made

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Speaker 1: out of, and then let's think about whether we can

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Speaker 1: extrapolate that to the rest of the universe because unfortunately

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Speaker 1: we still can't go visit most of the universe. So

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Speaker 1: in terms of like lab science and like getting our

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Speaker 1: fingers literally dirty, the Earth is the only place we

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Speaker 1: have to explore. And it's really cool story how we

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Speaker 1: figured out what the Earth is made out of it

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Speaker 1: because even though it's under our feet, we can't go

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Speaker 1: like explore very deep. We haven't drilled very far into

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Speaker 1: the earth, so a lot of it is still indirect

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Speaker 1: evidence that we put together by clever humans figuring out

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Speaker 1: ways to basically see what's inaccessible.

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Speaker 2: Well not only getting to the center of the Earth,

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Speaker 2: but just being able to like pick up a handful

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Speaker 2: of dirt and being like, what kind of elements are

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Speaker 2: in this handful of dirt. That's amazing to.

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Speaker 1: Me as well exactly, and this requires a lot of

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Speaker 1: you know, chemistry, understanding what elements were there and their

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Speaker 1: properties and their mixture, and so early on in the

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Speaker 1: last few hundred years, when people are trying to figure out, like, hey,

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Speaker 1: what is the Earth made out of they're basically three

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Speaker 1: big questions that were asking. One is like, what is

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Speaker 1: the density of the earth? Can we figure that out?

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Speaker 1: Because if we know the density of the Earth. We

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Speaker 1: know a lot about what it could be made out

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Speaker 1: of and what it couldn't. Like if you measure the

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Speaker 1: density of the earth and you discover, oh, it has

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Speaker 1: the density of whipped then you know it's not mostly ironed, right,

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Speaker 1: Whereas if you measure the density the earth and it's

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Speaker 1: like bang on nickel, then you're like, wow, it's probably

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Speaker 1: most any nickel. Right. And so measuring the density of

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Speaker 1: the earth is an important question. But this isn't easy, right, Like,

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Speaker 1: how do you measure the density of something? Well, here

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Speaker 1: on Earth, You like put it in water and see

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Speaker 1: if it floats, or you measure its mass and you

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Speaker 1: measure its volume, right, the famous Eureka moment of figuring

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Speaker 1: out whether the crown is made of gold by measuring

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Speaker 1: its volume by dipping it in water, et cetera, et cetera.

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Speaker 2: This is apparently not a particularly famous Eureka moment because

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Speaker 2: I've never heard that story.

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Speaker 1: Oh this is a really fun Mas story. Archimedes was

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Speaker 1: asked to determine whether the king's crown was made of

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Speaker 1: pure gold or not, so he said, well, I'll measure

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Speaker 1: its density, because if it's density lines up with gold,

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Speaker 1: then we know it's gold, and if it's got something

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Speaker 1: else in it, it'll come out a different number. Measure

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Speaker 1: the density requires them in the mass and the volume.

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Speaker 1: Mass not so hard, Volume not so hard. If you

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Speaker 1: have a simple object like a sphere or a cube,

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Speaker 1: how do you measure very precisely the volume of a

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Speaker 1: really complex shape like a crown turns out to be

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Speaker 1: really challenging. So Archimedies is puzzling over this as he's

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Speaker 1: slipping into the bath at the end of his day.

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Speaker 1: And as he gets into the bath, he sees the

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Speaker 1: water level rise, and he's like, oh, now, I understand

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Speaker 1: how to measure the volume. You just dip it in

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Speaker 1: water and you measure how much it rises. And the

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Speaker 1: story goes, probably apocryphally, that he left out of the

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Speaker 1: baths and naked down the streets of Siracuse or Syracuse,

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Speaker 1: shouting eureka, eureka. And anyway, that's your famous ancient Greek

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Speaker 1: nude story for the day.

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Speaker 2: Amazing. We should have more of those, But okay, I

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Speaker 2: hadn't heard that story. Thanks for sharing.

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Speaker 1: But in the case of the earth, you can't just

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Speaker 1: dip the earth in water, right, you know, we don't

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Speaker 1: have like a bath of water that we could dip

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Speaker 1: it in. So what we need to do is measure

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Speaker 1: the gravitational pull of the Earth. Right, if you knew

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Speaker 1: the total mass and the volume, then you would have

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Speaker 1: the density and the volume is pretty straightforward because the

256
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Speaker 1: Earth is a spear. So if you could figure out

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Speaker 1: the mass, then you'd know the answer. But figuring out

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Speaker 1: the mass is a little bit complicated because to do

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Speaker 1: that you have to measure the pull of gravity, and

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Speaker 1: to do that you have to know so the constant

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Speaker 1: in the gravitational formula Newton's gravitational formula says that the

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Speaker 1: pole of gravity depends on two masses and on this

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Speaker 1: number in between them. And for a long time we

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Speaker 1: didn't know very precisely that number. And so to get

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Speaker 1: that number you need like two large known masses that

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Speaker 1: you can measure their gravitational pole between them, so you

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Speaker 1: can get that number, and then you can measure gravity

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Speaker 1: in the Earth and finally figure out what is the

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Speaker 1: mass of the Earth.

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Speaker 2: That sounds complicated, and so how did they find two

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Speaker 2: massive objects to do this with?

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Speaker 1: Yeah, they have to be massive objects because gravity is

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Speaker 1: super duper weak. Right, you can't measure the gravitational pole

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Speaker 1: between like two pennies in your hand. There is a

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Speaker 1: gravitational pole there, but it's unmeasurable, especially like one hundred

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Speaker 1: two hundred years ago. So what they did is they

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Speaker 1: found a mountain. There's this mountain in Scotland called she Holand,

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Speaker 1: and in the seventeen seventies that decided this was a

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Speaker 1: good candidate for measuring the gravitational constant because it's isolated

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Speaker 1: from lots of other stuff. So it's like a single

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Speaker 1: mountain on a plane, far away from other stuff, and

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Speaker 1: it's kind of symmetrical. It's like not hard to measure

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Speaker 1: its volume pretty accurately. It's not like the crown of

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Speaker 1: the King of Syracuse, right, it's like kind of a

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Speaker 1: simple shape.

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Speaker 2: Okay, so there's one massive object.

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Speaker 1: Yeah. So then they took a pendulum and they held

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Speaker 1: it near the mountain and they measured weather deviated from

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Speaker 1: straight down, and the deviation of the pendulum from straight

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Speaker 1: down as you get closer and further from the mountain

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Speaker 1: is a measure of the gravitational pull of the mountain

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Speaker 1: on the pendulum. Right. So here you're like actually measuring

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Speaker 1: gravity between two things, neither of which are the Earth

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Speaker 1: that works, actually does work. This was the first measurement

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Speaker 1: of the gravitational constant, and it required actually a lot

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Speaker 1: of work by surveyors, like converting the shape of the

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Speaker 1: mountain into prisms so they could calculate the volume very accurately.

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Speaker 1: It was a huge project, and that allowed them to

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Speaker 1: measure the gravitational constant and then calculate the density of

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Speaker 1: the Earth. And they discovered that the day to the

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Speaker 1: Earth is like almost twice the density of that mountain.

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Speaker 2: So this technique sounds incredibly complicated. How close did they

303
00:14:09,000 --> 00:14:10,960
Speaker 2: get to the value that we believe it is today?

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Speaker 1: They're within twenty percent.

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Speaker 2: Nice.

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Speaker 1: Yeah, and that's pretty good, you know for dudes in

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Speaker 1: silly hats with pendulums, you know, walking around mountains like

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Speaker 1: these clever apes are figuring stuff out.

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Speaker 2: Yeah, no, that's amazing.

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Speaker 3: You know.

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Speaker 2: I feel like if you took five biologists in our

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Speaker 2: field clothes or whatever and you were like figure out

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Speaker 2: the density of the Earth, I'd feel pretty good if

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Speaker 2: we got within twenty percent. That's pretty solid.

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Speaker 1: And that is really revealing at the time, because people

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Speaker 1: had no idea what was inside the earth? Is it

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Speaker 1: like a hall of core? The way like King Kong

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Speaker 1: and Godzilla are fighting down there? Is it mostly made

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Speaker 1: of water? People really just didn't know. And this in

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Speaker 1: a single measurement tells you a lot about what the

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Speaker 1: Earth could and couldn't be made out of. And then

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Speaker 1: there's a really amazing history of the measurements of the

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Speaker 1: gravitational constant, which got more and more precise. Eventually people

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Speaker 1: used torsion experiments like balls hanging on strings that are

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Speaker 1: very sensitive and measured their deflection as it got closer

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Speaker 1: together Cavendish et cetera. There's a whole fun history there.

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Speaker 1: People made these measurements very precisely to within less than

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Speaker 1: one percent. So now we have a very accurate estimate

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Speaker 1: of the Earth's density.

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Speaker 2: That is incredible. Okay, so we have an estimate of

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Speaker 2: the density, what did it lead us to believe? That

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Speaker 2: most of the Earth is made of yees?

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Speaker 1: So the density of the Earth is more dense than

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Speaker 1: the mountain, which is a hint that there's like heavy

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Speaker 1: stuff in there. Right, it can't just be rock. It's

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Speaker 1: not water, right. Water is much less dense than the Earth,

337
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Speaker 1: and so that suggests that there's a dense core, that

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Speaker 1: there's something heavy in there. And we now know, of course,

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Speaker 1: there's a lot of nickel and iron in the core

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Speaker 1: of the Earth. And this was our first hint about

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Speaker 1: what was down there.

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Speaker 2: Not a giant open sphere with like dinosaurs hiding in it,

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Speaker 2: because that would have been cooler, Not.

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Speaker 1: A vast chasm filled with swarming parasites, for example. For

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Speaker 1: most people, that's a nightmare. For you, that's heaven.

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Speaker 2: Now, I'm so bummed out to know that this is

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Speaker 2: the Earth I exist on, but it could have been

348
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Speaker 2: so much better.

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Speaker 1: And people attack this question of what is the Earth

350
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Speaker 1: made at of? From other angles. We have density, but

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Speaker 1: the next angle was age. People were trying to estimate,

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Speaker 1: like how old is the Earth, because understanding how old

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Speaker 1: the Earth is gives you clues about how it's formed

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Speaker 1: and therefore what it's made out of. And we already

355
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Speaker 1: knew at this point a couple hundred years ago that

356
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Speaker 1: the Earth was probably pretty old. And the biggest clue

357
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Speaker 1: there was like Darwin, Darwin should us that life took

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Speaker 1: a while to come together, you know, this process of

359
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Speaker 1: evolution was slow, so we had a sense that the

360
00:16:31,800 --> 00:16:35,280
Speaker 1: Earth was like cosmically old, not thousands of years, but

361
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Speaker 1: people didn't really know is that like millions, hundreds of millions, billions,

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Speaker 1: even it was still an open question a couple hundred

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Speaker 1: years ago.

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Speaker 2: Now, I love when Darwin gets credit for stuff, but

365
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Speaker 2: I don't actually know that he should get credit for

366
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Speaker 2: showing us that life was ancient. I mean he was.

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Speaker 2: He came up with the theory of natural selection to

368
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Speaker 2: explain how like one form sort of morphs into another.

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Speaker 2: But I think there were geologists already working on this

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Speaker 2: question and finding fossils and postulating Earth has been around

371
00:17:01,120 --> 00:17:03,400
Speaker 2: for a long time and stuff has been gone. But anyway,

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00:17:03,480 --> 00:17:06,359
Speaker 2: Darwin awesome. Maybe he just got some credit for something

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00:17:06,359 --> 00:17:09,480
Speaker 2: he didn't deserve, but biologist getting credit for stuff is

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Speaker 2: always awesome, So let's move on.

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Speaker 1: Yeah, that's fair, And I'm about to give some credit

376
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Speaker 1: to some chemists to hold onto your hats.

377
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Speaker 2: Oh oh boy, I'm gonna get sour.

378
00:17:18,200 --> 00:17:20,439
Speaker 1: People were wondering, like, how long would it take the

379
00:17:20,480 --> 00:17:22,760
Speaker 1: Earth to cool if you have a like a ball

380
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Speaker 1: of molten stuff sitting in space, how quickly does it

381
00:17:26,480 --> 00:17:28,840
Speaker 1: form a crust that you can like walk around on.

382
00:17:29,280 --> 00:17:32,840
Speaker 1: And Lord Kelvin of you know, Kelvin temperature trying to

383
00:17:32,920 --> 00:17:35,720
Speaker 1: use this to calculate an approximate age for the Earth.

384
00:17:36,160 --> 00:17:38,000
Speaker 1: He was thinking, like, you have a big ball of

385
00:17:38,119 --> 00:17:41,480
Speaker 1: lava basically or magma in space, how quickly can you

386
00:17:41,520 --> 00:17:44,240
Speaker 1: form a crust? And he ignored a bunch of stuff

387
00:17:44,280 --> 00:17:47,040
Speaker 1: like he didn't understand that there was convection inside the

388
00:17:47,080 --> 00:17:49,960
Speaker 1: Earth that hot stuff rises, and so you keep getting

389
00:17:50,000 --> 00:17:52,800
Speaker 1: this like refresher of hot stuff from the core up

390
00:17:52,880 --> 00:17:56,120
Speaker 1: to the surface. He also didn't know about radioactive decay,

391
00:17:56,240 --> 00:17:58,680
Speaker 1: which helps heat the Earth, because he didn't know about

392
00:17:58,760 --> 00:18:01,199
Speaker 1: radiation and quantum mechanics and all that stuff. Nobody had

393
00:18:01,200 --> 00:18:05,280
Speaker 1: discovered that yet. So in Kelvin's calculation, he missed a

394
00:18:05,280 --> 00:18:07,199
Speaker 1: lot of the pieces there, and he came up with

395
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Speaker 1: a range of like twenty to four hundred million years,

396
00:18:11,119 --> 00:18:13,280
Speaker 1: which is like low by more than a factor of

397
00:18:13,320 --> 00:18:15,320
Speaker 1: ten because of these pieces he missed. But you know,

398
00:18:15,640 --> 00:18:18,360
Speaker 1: he's sort of getting up there into the right ballpark.

399
00:18:18,680 --> 00:18:21,240
Speaker 2: Yeah. And so at the time was the predominant view,

400
00:18:21,320 --> 00:18:23,680
Speaker 2: the Christian view, that the Earth was like what two

401
00:18:23,840 --> 00:18:26,680
Speaker 2: or five thousand years old or something. I think postulating

402
00:18:26,920 --> 00:18:29,000
Speaker 2: millions of years could have really like put you in

403
00:18:29,040 --> 00:18:31,760
Speaker 2: the crosshairs. But how common was the idea that it

404
00:18:31,800 --> 00:18:33,879
Speaker 2: was just a couple thousand years old at that point.

405
00:18:34,040 --> 00:18:37,120
Speaker 1: I think that most educated and scientific people didn't accept

406
00:18:37,240 --> 00:18:40,000
Speaker 1: the young Earth hypothesis. Even back then, there was a sense,

407
00:18:40,359 --> 00:18:43,000
Speaker 1: as you said, from geology that things were taking a

408
00:18:43,040 --> 00:18:45,320
Speaker 1: long time. But then people were trying to make a

409
00:18:45,320 --> 00:18:48,080
Speaker 1: specific They're like, can we get an actual number? And

410
00:18:48,119 --> 00:18:49,719
Speaker 1: so I love when people in history are like, well,

411
00:18:49,760 --> 00:18:51,639
Speaker 1: let's try to sit down and get a calculation of this,

412
00:18:51,720 --> 00:18:54,439
Speaker 1: and you know they're wildly off, but getting that first

413
00:18:54,600 --> 00:18:56,480
Speaker 1: estimate is a big step forward, and then you can

414
00:18:56,520 --> 00:18:58,439
Speaker 1: refine it and think about what you're missing, And like,

415
00:18:58,720 --> 00:19:01,000
Speaker 1: this is the process of science, right, First do the

416
00:19:01,080 --> 00:19:04,120
Speaker 1: dumbest thing and then improve it. It's innerative, right.

417
00:19:04,280 --> 00:19:05,760
Speaker 2: I feel like that's kind of where we are with

418
00:19:05,800 --> 00:19:08,560
Speaker 2: the Drake equation, Like we're starting to hone in on

419
00:19:08,600 --> 00:19:11,080
Speaker 2: the things that matter, and exercises like this help you

420
00:19:11,119 --> 00:19:11,879
Speaker 2: think through stuff.

421
00:19:11,960 --> 00:19:14,359
Speaker 1: Yeah, exactly. And now, of course we know a lot

422
00:19:14,480 --> 00:19:16,480
Speaker 1: more precisely how old the Earth.

423
00:19:16,280 --> 00:19:17,960
Speaker 2: Is, and when we get back from the break, we're

424
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Speaker 2: going to hear all about that, all right. So Dan

425
00:19:41,240 --> 00:19:44,080
Speaker 2: was just telling us that Kelvin was thinking about how

426
00:19:44,119 --> 00:19:46,159
Speaker 2: long it would take a molten earth to cool to

427
00:19:46,160 --> 00:19:48,200
Speaker 2: get our initial estimates for the age of the Earth,

428
00:19:48,240 --> 00:19:50,840
Speaker 2: and we ended up with somewhere between twenty and four

429
00:19:50,920 --> 00:19:53,879
Speaker 2: hundred million years. What was the next step that we

430
00:19:53,880 --> 00:19:55,680
Speaker 2: took to get more accurate.

431
00:19:55,600 --> 00:19:58,080
Speaker 1: More accurate understanding the age of the Earth, which again

432
00:19:58,119 --> 00:20:00,320
Speaker 1: helps you understand what it's made out of. It came

433
00:20:00,400 --> 00:20:03,400
Speaker 1: in this century when we understood that rocks have little

434
00:20:03,480 --> 00:20:06,000
Speaker 1: clocks in them, and you can use that to figure

435
00:20:06,000 --> 00:20:08,960
Speaker 1: out when the rock cooled, so you can figure out

436
00:20:09,080 --> 00:20:12,960
Speaker 1: like when something was formed, and these clocks actually depend

437
00:20:13,040 --> 00:20:16,680
Speaker 1: on quantum mechanics. There are these little crystals called zircon

438
00:20:16,800 --> 00:20:19,480
Speaker 1: crystals that help you understand how old a.

439
00:20:19,480 --> 00:20:22,520
Speaker 2: Rock is, and what is it about the zircon crystals

440
00:20:22,520 --> 00:20:24,600
Speaker 2: and why isn't there a watch company called Zircon.

441
00:20:26,200 --> 00:20:29,080
Speaker 1: Zircon are really weird little crystals that hate lead, like

442
00:20:29,119 --> 00:20:31,920
Speaker 1: they will not allow lead to form within the crystal,

443
00:20:32,240 --> 00:20:35,159
Speaker 1: but they will take uranium. So when you get a

444
00:20:35,240 --> 00:20:38,479
Speaker 1: zircon crystal freshly formed, it has no lead in it,

445
00:20:38,600 --> 00:20:41,760
Speaker 1: but it does have uranium in it, and then uranium

446
00:20:41,800 --> 00:20:45,480
Speaker 1: while it's inside the crystal decays naturally into lead at

447
00:20:45,480 --> 00:20:47,600
Speaker 1: a rate we know. So if you pick up a

448
00:20:47,680 --> 00:20:50,520
Speaker 1: random zircon crystal and it has no lead in it.

449
00:20:50,600 --> 00:20:52,720
Speaker 1: You know, this thing is zero years old. It's a

450
00:20:52,720 --> 00:20:55,359
Speaker 1: baby crystal. If you pick up a zircon crystal and

451
00:20:55,400 --> 00:20:58,119
Speaker 1: it's got no uranium and it's pure lead, you're like, wow,

452
00:20:58,160 --> 00:21:02,160
Speaker 1: this thing is old because uranium is slow at decaying.

453
00:21:02,760 --> 00:21:05,359
Speaker 1: So every zircon crystal is like a little clock that

454
00:21:05,440 --> 00:21:08,000
Speaker 1: tells you how long it's been since it's formed.

455
00:21:08,240 --> 00:21:08,920
Speaker 2: That's amazing.

456
00:21:09,000 --> 00:21:11,880
Speaker 1: And there's a whole incredible story about a Chemisty Patterson,

457
00:21:12,040 --> 00:21:14,560
Speaker 1: who figured this out and then started measuring the lead

458
00:21:14,640 --> 00:21:17,160
Speaker 1: and stuff. And he's actually the guy who discovered, oh

459
00:21:17,160 --> 00:21:19,720
Speaker 1: my gosh, this lead everywhere in our environment because of

460
00:21:19,800 --> 00:21:22,600
Speaker 1: lead in gasoline, and he led the crusade to get

461
00:21:22,680 --> 00:21:25,119
Speaker 1: lead out of gasoline because he was realizing, wow, we

462
00:21:25,160 --> 00:21:27,960
Speaker 1: have poisoned our environment. He was trying to make a

463
00:21:28,000 --> 00:21:30,159
Speaker 1: clean room to measure these things really precisely, and he

464
00:21:30,280 --> 00:21:33,240
Speaker 1: just could not get a lead free environment. Wow. And

465
00:21:33,600 --> 00:21:36,520
Speaker 1: so anyway, another chemist who saved us all.

466
00:21:36,400 --> 00:21:38,720
Speaker 2: When it's so hard to know, like what study you're

467
00:21:38,760 --> 00:21:40,520
Speaker 2: doing is going to be the thing that gives you

468
00:21:40,560 --> 00:21:43,320
Speaker 2: important information for humans, like what sort of off ramps

469
00:21:43,359 --> 00:21:44,199
Speaker 2: you're going to end up on?

470
00:21:44,440 --> 00:21:48,000
Speaker 1: And so another argument for funding basic science people. But

471
00:21:48,280 --> 00:21:51,640
Speaker 1: you never know what you're going to discuss important and

472
00:21:51,680 --> 00:21:53,960
Speaker 1: so because of his work, we discovered that the Earth

473
00:21:54,040 --> 00:21:57,080
Speaker 1: is like four and a half billion years old, meaning

474
00:21:57,280 --> 00:21:59,680
Speaker 1: that the oldest rocks we have cooled around four and

475
00:21:59,720 --> 00:22:01,040
Speaker 1: a half billion years ago.

476
00:22:01,240 --> 00:22:04,439
Speaker 2: Oh my gosh. And that's pretty close to our current estimate,

477
00:22:04,600 --> 00:22:04,960
Speaker 2: isn't it.

478
00:22:05,119 --> 00:22:06,040
Speaker 1: Yeah, yeah, exactly.

479
00:22:06,119 --> 00:22:06,639
Speaker 2: That's amazing.

480
00:22:06,680 --> 00:22:09,080
Speaker 1: And so now understanding that the Earth is really old

481
00:22:09,240 --> 00:22:11,720
Speaker 1: gives you more information to figure out the puzzle of like, well,

482
00:22:11,760 --> 00:22:14,320
Speaker 1: what's it made out of? Because you want to understand

483
00:22:14,320 --> 00:22:17,240
Speaker 1: like how old is the Earth, how quickly did it cool? Well,

484
00:22:17,240 --> 00:22:18,919
Speaker 1: to know that you have to know like where's the

485
00:22:18,920 --> 00:22:21,280
Speaker 1: heat coming from? Where are the layers inside the earth?

486
00:22:21,320 --> 00:22:24,080
Speaker 1: You need a complete model for where stuff is within

487
00:22:24,119 --> 00:22:26,639
Speaker 1: the earth, and that's why you need this last piece.

488
00:22:26,840 --> 00:22:28,840
Speaker 1: So we have the age, we have the density. Next

489
00:22:28,840 --> 00:22:30,960
Speaker 1: thing we need is the structure of the earth to

490
00:22:31,040 --> 00:22:34,720
Speaker 1: know like how a stuff organized within the earth. And

491
00:22:34,760 --> 00:22:37,600
Speaker 1: that's where seismology comes in to give us that last piece.

492
00:22:37,840 --> 00:22:41,679
Speaker 2: Oh so we're getting away from chemistry, whew. Back to

493
00:22:41,720 --> 00:22:42,800
Speaker 2: the rock people.

494
00:22:43,640 --> 00:22:46,760
Speaker 1: Of seismology, of course, it's a study of earthquakes and

495
00:22:46,920 --> 00:22:49,879
Speaker 1: earthquakes are cool. I mean, they're devastating and tragic, but

496
00:22:49,920 --> 00:22:52,520
Speaker 1: they also do something really useful, which is that they

497
00:22:52,640 --> 00:22:55,440
Speaker 1: ring the Earth like a bell. And so when there's

498
00:22:55,480 --> 00:22:59,159
Speaker 1: an earthquake, these seismic waves pass through the Earth and

499
00:22:59,200 --> 00:23:01,280
Speaker 1: they give you a glimp as to what's going on

500
00:23:01,440 --> 00:23:05,920
Speaker 1: inside the Earth because these waves bounce off of like interfaces.

501
00:23:06,440 --> 00:23:08,800
Speaker 1: If the whole Earth was just like one solid rock,

502
00:23:09,000 --> 00:23:11,320
Speaker 1: then the waves would travel smoothly through it. But if

503
00:23:11,359 --> 00:23:13,120
Speaker 1: there's an interface where you go from like one kind

504
00:23:13,119 --> 00:23:15,119
Speaker 1: of rock to another, or you go from like nickel

505
00:23:15,119 --> 00:23:18,400
Speaker 1: to iron, or liquid to not liquid, then the waves

506
00:23:18,480 --> 00:23:21,840
Speaker 1: bounce back at that surface and you create complicated patterns.

507
00:23:22,119 --> 00:23:24,840
Speaker 1: And so by reading the waves that reflect on the surface,

508
00:23:24,920 --> 00:23:27,880
Speaker 1: you can reconstruct what was going on inside the Earth.

509
00:23:27,880 --> 00:23:31,199
Speaker 1: It's sort of like a sonogram, right, or an ultrasound.

510
00:23:30,760 --> 00:23:34,199
Speaker 2: That that is absolutely amazing. And just like parents like

511
00:23:34,240 --> 00:23:37,000
Speaker 2: to brag about their kids, I like to brag about

512
00:23:37,040 --> 00:23:40,520
Speaker 2: the human species sometimes, and just note that we've measured

513
00:23:41,200 --> 00:23:44,119
Speaker 2: Mars quakes and it is just amazing to me that

514
00:23:44,160 --> 00:23:46,280
Speaker 2: we've been able to like get equipment there that could

515
00:23:46,320 --> 00:23:50,000
Speaker 2: then measure this happening on another planet in our solar system.

516
00:23:50,080 --> 00:23:52,880
Speaker 2: So anyway, okay, amazing, all right, so now you can

517
00:23:53,040 --> 00:23:55,159
Speaker 2: you can do this. And so did we know at

518
00:23:55,160 --> 00:23:57,240
Speaker 2: the time enough to figure out so like you know,

519
00:23:57,240 --> 00:23:59,440
Speaker 2: if you hit water and you had been going through nickel,

520
00:23:59,440 --> 00:24:02,480
Speaker 2: you're like, oh, some thing is different. How much work

521
00:24:02,520 --> 00:24:05,560
Speaker 2: did we have to do to understand what we were seeing?

522
00:24:05,600 --> 00:24:07,560
Speaker 2: Like it seems like there's a big difference between saying

523
00:24:07,760 --> 00:24:11,879
Speaker 2: something changed or something changed and I understand what that means.

524
00:24:12,280 --> 00:24:15,120
Speaker 1: Yeah, the crucial thing there is having enough instrumented points,

525
00:24:15,400 --> 00:24:17,920
Speaker 1: like you need to reconstruct these waves all across the Earth,

526
00:24:18,000 --> 00:24:20,760
Speaker 1: because like a wave from an earthquake in California will

527
00:24:20,760 --> 00:24:23,960
Speaker 1: propagate down into the Earth and reflect back, but doesn't

528
00:24:23,960 --> 00:24:26,400
Speaker 1: come straight back to California and like goes to Japan

529
00:24:26,520 --> 00:24:29,840
Speaker 1: or Hawaii or somewhere else, and it also continues through

530
00:24:29,880 --> 00:24:31,800
Speaker 1: the Earth, and the different parts of the wave is

531
00:24:31,840 --> 00:24:34,639
Speaker 1: like s waves and pea waves, and different frequencies reflect

532
00:24:34,680 --> 00:24:36,680
Speaker 1: at different rates. And so what you really need to

533
00:24:36,720 --> 00:24:39,359
Speaker 1: do is measure all the different frequencies as many places

534
00:24:39,400 --> 00:24:41,800
Speaker 1: as you can around the Earth to get this complete picture.

535
00:24:42,720 --> 00:24:45,520
Speaker 1: So that's what's crucial is having this like global network

536
00:24:45,640 --> 00:24:48,480
Speaker 1: of seismic grass and yeah, on Mars they have a

537
00:24:48,520 --> 00:24:50,439
Speaker 1: few of these, but wow, if they had more, they

538
00:24:50,440 --> 00:24:53,360
Speaker 1: could really get pictures of these marsquakes and understand what's

539
00:24:53,400 --> 00:24:56,040
Speaker 1: going on inside the Martian core, which is a whole

540
00:24:56,040 --> 00:24:59,000
Speaker 1: other fascinating question about like whether there is still motion

541
00:24:59,160 --> 00:25:02,719
Speaker 1: inside the core or whether it's totally frozen. And of

542
00:25:02,720 --> 00:25:04,479
Speaker 1: course that tells us a lot about like the history

543
00:25:04,480 --> 00:25:07,040
Speaker 1: of Mars and maybe did it have a magnetic field

544
00:25:07,160 --> 00:25:10,800
Speaker 1: and could it protect life from cosmic radiation? But anyway,

545
00:25:11,080 --> 00:25:14,399
Speaker 1: that's off track. Coming back to Earth. We now have

546
00:25:14,480 --> 00:25:16,520
Speaker 1: an idea of what the structure of the Earth is,

547
00:25:16,800 --> 00:25:19,360
Speaker 1: where the density of the Earth is, and how long

548
00:25:19,440 --> 00:25:22,320
Speaker 1: it's been cooling, and altogether that gives us a model

549
00:25:22,560 --> 00:25:25,160
Speaker 1: for what's going on inside the Earth without drilling down

550
00:25:25,200 --> 00:25:28,000
Speaker 1: and going to visit. This is enough information to constrain

551
00:25:28,040 --> 00:25:29,600
Speaker 1: our model and tell us what it has to be

552
00:25:29,640 --> 00:25:31,879
Speaker 1: made out of, each of the layers and their composition.

553
00:25:32,280 --> 00:25:33,879
Speaker 2: And so this is how we figured out that the

554
00:25:33,880 --> 00:25:37,200
Speaker 2: core is mostly nickel and lead, not lead iron.

555
00:25:37,320 --> 00:25:39,600
Speaker 1: Nickel and iron and iron got it. And so it

556
00:25:39,640 --> 00:25:42,399
Speaker 1: turns out that the Earth is like thirty two percent

557
00:25:42,480 --> 00:25:45,879
Speaker 1: iron thirty percent oxygen, which blows my mind. Most of

558
00:25:45,920 --> 00:25:51,119
Speaker 1: it's like absorbed into rock. Fifteen percent silicon, fourteen percent magnesium,

559
00:25:51,200 --> 00:25:54,080
Speaker 1: three percent sulfur, two percent nickel, and the rest of

560
00:25:54,160 --> 00:25:57,920
Speaker 1: a lot of exciting trace elements. But that's the majority

561
00:25:57,920 --> 00:25:59,119
Speaker 1: of what the Earth is made out of.

562
00:25:59,320 --> 00:26:01,600
Speaker 2: Well, okay, so that's not a lot of nickel, So

563
00:26:01,680 --> 00:26:04,040
Speaker 2: with mostly iron and oxygen.

564
00:26:04,320 --> 00:26:07,680
Speaker 1: Mostly iron and oxygen, huh, yeah, exactly. There's a lot

565
00:26:07,760 --> 00:26:11,879
Speaker 1: of oxygen in the Earth because rocks gobble up oxygen.

566
00:26:12,080 --> 00:26:13,960
Speaker 1: Like in the early days of the Earth, when you

567
00:26:14,119 --> 00:26:16,720
Speaker 1: be produced oxygen in the atmosphere, most of it was

568
00:26:16,800 --> 00:26:19,840
Speaker 1: just absorbed by rocks. You have to like satisfy all

569
00:26:19,880 --> 00:26:22,280
Speaker 1: the rocks before you could leave oxygen in the atmosphere

570
00:26:22,320 --> 00:26:22,760
Speaker 1: for life.

571
00:26:23,880 --> 00:26:25,640
Speaker 2: I'm glad there was some leftover for us.

572
00:26:25,760 --> 00:26:28,639
Speaker 1: Yeah, because oxygen is so reactive. So that gives us

573
00:26:28,640 --> 00:26:30,879
Speaker 1: a sense for what our scoop of the universe is

574
00:26:30,920 --> 00:26:34,199
Speaker 1: made out of, right, iron, oxygen, silicon, magnesium. But then

575
00:26:34,240 --> 00:26:36,080
Speaker 1: of course we're wondering, like what's the rest of the

576
00:26:36,160 --> 00:26:38,640
Speaker 1: universe made out of? Is it the same? Is it different?

577
00:26:38,680 --> 00:26:40,920
Speaker 1: What's the Sun made out of? And this is a

578
00:26:41,000 --> 00:26:43,119
Speaker 1: question people had for a long time, like what is

579
00:26:43,160 --> 00:26:45,320
Speaker 1: the Sun made out of how does it work, what's

580
00:26:45,359 --> 00:26:47,720
Speaker 1: going on inside of it, and what fuels it?

581
00:26:47,800 --> 00:26:49,720
Speaker 2: Yeah, because I think all of the techniques that we've

582
00:26:49,760 --> 00:26:52,199
Speaker 2: talked about require you to be on the surface of

583
00:26:52,200 --> 00:26:55,399
Speaker 2: that planet to collect the data, so you probably need

584
00:26:55,440 --> 00:26:57,560
Speaker 2: a whole different set of tools to figure out what's

585
00:26:57,560 --> 00:26:58,880
Speaker 2: happening on the Sun.

586
00:26:58,760 --> 00:27:01,840
Speaker 1: Right, Yeah, exactly, And of course we can't go visit

587
00:27:01,880 --> 00:27:04,440
Speaker 1: the Sun. We had the Parker Solar Probe, which came

588
00:27:04,520 --> 00:27:06,600
Speaker 1: close to the Sun, but of course didn't go into

589
00:27:06,600 --> 00:27:08,960
Speaker 1: the Sun. And for a long time we were trying

590
00:27:08,960 --> 00:27:10,760
Speaker 1: to figure this out, of course, just from Earth and

591
00:27:10,800 --> 00:27:12,520
Speaker 1: trying to understand what it could be made out of.

592
00:27:12,600 --> 00:27:14,560
Speaker 1: And we can know some things without going to visit

593
00:27:14,640 --> 00:27:16,639
Speaker 1: the Sun. Right. We can get a sense of the

594
00:27:16,680 --> 00:27:19,200
Speaker 1: mass of the Sun if we know the gravitational constant

595
00:27:19,440 --> 00:27:21,800
Speaker 1: and we know Earth's mass, and then we can calculate

596
00:27:21,840 --> 00:27:24,960
Speaker 1: from the Earth's orbit how strong the Sun's gravity has

597
00:27:25,000 --> 00:27:27,119
Speaker 1: to be to keep us in orbit. So already we

598
00:27:27,200 --> 00:27:29,640
Speaker 1: know the Sun's mass, right, which gives us a lot

599
00:27:29,680 --> 00:27:32,000
Speaker 1: of clues, but we don't know much about the density

600
00:27:32,040 --> 00:27:33,920
Speaker 1: and what's going on inside there.

601
00:27:34,040 --> 00:27:35,919
Speaker 2: Or the age. Right. We decided we needed to know

602
00:27:36,000 --> 00:27:37,320
Speaker 2: age too, Yeah.

603
00:27:37,160 --> 00:27:39,920
Speaker 1: And another crucial hint is while the Sun is very bright,

604
00:27:40,119 --> 00:27:43,639
Speaker 1: so something going on inside the Sun producing that energy,

605
00:27:43,680 --> 00:27:46,440
Speaker 1: and it's like an incredible amount of energy. I don't

606
00:27:46,440 --> 00:27:49,320
Speaker 1: think people really appreciate how much energy is being put

607
00:27:49,359 --> 00:27:52,680
Speaker 1: out by the Sun, Like we capture the tiniest, tiniest

608
00:27:52,720 --> 00:27:55,920
Speaker 1: little fraction of it. But the Sun's total power outage

609
00:27:56,080 --> 00:27:59,520
Speaker 1: is four times ten to the twenty six watts. Wow,

610
00:27:59,560 --> 00:28:03,719
Speaker 1: which is like ten quadrillion times the amount of power

611
00:28:03,760 --> 00:28:07,600
Speaker 1: released by the most energetic power plants ever constructed on Earth. Wow,

612
00:28:07,840 --> 00:28:11,160
Speaker 1: it's just we are sipping from an ocean of energy here.

613
00:28:11,200 --> 00:28:14,240
Speaker 1: That's just like being blasted out into space.

614
00:28:14,080 --> 00:28:15,520
Speaker 2: And it powers our whole planet.

615
00:28:15,840 --> 00:28:18,880
Speaker 1: It really does. And people wondered for a long time

616
00:28:19,040 --> 00:28:22,119
Speaker 1: like what's producing all that energy? How long has the

617
00:28:22,160 --> 00:28:25,280
Speaker 1: Sun been burning? They're wondering like is there something up

618
00:28:25,280 --> 00:28:28,000
Speaker 1: there that's on fire? And that of course is a

619
00:28:28,040 --> 00:28:29,840
Speaker 1: clue to what the Sun might be made out of.

620
00:28:29,960 --> 00:28:31,680
Speaker 1: People were wondering like is it made at the same

621
00:28:31,680 --> 00:28:34,040
Speaker 1: stuff as the Earth somehow? Is it made out of

622
00:28:34,040 --> 00:28:38,840
Speaker 1: something different? So re enter Lord Kelvin, King of approximate

623
00:28:38,840 --> 00:28:41,120
Speaker 1: initial terrible estimates of what the universe is.

624
00:28:41,080 --> 00:28:44,640
Speaker 2: Made out of would I. I guess I'd be happy

625
00:28:44,680 --> 00:28:46,520
Speaker 2: if I was known for anything, but I do feel

626
00:28:46,560 --> 00:28:48,400
Speaker 2: like I wouldn't really want to be known for that

627
00:28:48,440 --> 00:28:49,200
Speaker 2: in particular.

628
00:28:49,360 --> 00:28:51,719
Speaker 1: No, I love that situation, like getting the first bited

629
00:28:51,760 --> 00:28:54,760
Speaker 1: some apples, some fascinating question nobody's tackled. Those are the

630
00:28:54,800 --> 00:28:57,280
Speaker 1: funnest ones I'm jealous of, Like the Greeks and the

631
00:28:57,360 --> 00:28:59,680
Speaker 1: Sumerians and the ancient Chinese and the Mayans who got

632
00:28:59,720 --> 00:29:03,040
Speaker 1: to think about these questions that nobody had worked on before, right,

633
00:29:03,280 --> 00:29:06,520
Speaker 1: like the answer could have been anything anyway. I think

634
00:29:06,560 --> 00:29:07,520
Speaker 1: that's super exciting.

635
00:29:07,840 --> 00:29:10,880
Speaker 2: One of my favorite stories along this line is there

636
00:29:11,000 --> 00:29:13,400
Speaker 2: was a guy who studied vaccines. His name was Sir

637
00:29:13,640 --> 00:29:16,560
Speaker 2: Wright w R I g h T. And he every

638
00:29:16,640 --> 00:29:21,080
Speaker 2: time got something important incorrect, and he ended up becoming

639
00:29:21,120 --> 00:29:26,280
Speaker 2: known as Sir not quite right and all right anyway,

640
00:29:26,440 --> 00:29:28,640
Speaker 2: tangent complete. Where were we?

641
00:29:29,160 --> 00:29:31,200
Speaker 1: So? Lord Kelvin is trying to understand what's the sun

642
00:29:31,280 --> 00:29:33,480
Speaker 1: man out of And first he thought, well, what if

643
00:29:33,480 --> 00:29:35,840
Speaker 1: it's just like fuel. You know, we have fire here

644
00:29:36,000 --> 00:29:38,600
Speaker 1: on Earth. If the Sun is a huge ball of

645
00:29:38,640 --> 00:29:42,280
Speaker 1: fuel that's chemically burning, could that explain what we're seeing,

646
00:29:42,560 --> 00:29:44,360
Speaker 1: you know? And that would tell you like, oh, maybe

647
00:29:44,360 --> 00:29:47,720
Speaker 1: the Sun is a huge ball of gasoline basically or

648
00:29:47,720 --> 00:29:50,560
Speaker 1: a curacy no runout. So if you do the calculation,

649
00:29:50,640 --> 00:29:53,440
Speaker 1: giving your knowledge the mass of the sun, chemical burning

650
00:29:53,480 --> 00:29:55,600
Speaker 1: can only produce that much power for like tens of

651
00:29:55,680 --> 00:29:59,560
Speaker 1: thousands of years, not for billions of years. Why because

652
00:29:59,640 --> 00:30:03,080
Speaker 1: chemical burning is very inefficient, like most of the energy

653
00:30:03,360 --> 00:30:06,360
Speaker 1: in mass is not released when you just like change

654
00:30:06,400 --> 00:30:09,280
Speaker 1: the chemical state from one to another. Whereas you know,

655
00:30:09,360 --> 00:30:11,600
Speaker 1: fusion is what's happening inside the Sun, and that's much

656
00:30:11,640 --> 00:30:14,640
Speaker 1: more efficient, much more effective release of energy. You get

657
00:30:14,680 --> 00:30:16,880
Speaker 1: a lot more energy out. And so if you want

658
00:30:16,920 --> 00:30:19,200
Speaker 1: to produce all the energy that the Sun is producing

659
00:30:19,240 --> 00:30:21,840
Speaker 1: and do it for billions of years, you can't rely

660
00:30:21,920 --> 00:30:25,719
Speaker 1: on like burning kerosene or some similar chemical process because

661
00:30:25,760 --> 00:30:28,160
Speaker 1: there just isn't enough mass in the Sun to keep

662
00:30:28,200 --> 00:30:29,600
Speaker 1: that going for billions of years.

663
00:30:29,880 --> 00:30:32,040
Speaker 2: All right, It's not logs on a fire. So how

664
00:30:32,040 --> 00:30:33,360
Speaker 2: do they figure out what it was?

665
00:30:34,000 --> 00:30:36,160
Speaker 1: Well, people went down other rabbit holes also, which is

666
00:30:36,200 --> 00:30:38,880
Speaker 1: really fun. They were thinking, maybe the Sun isn't limited

667
00:30:38,880 --> 00:30:41,200
Speaker 1: to its current mass. Maybe this is some source of mass?

668
00:30:41,280 --> 00:30:44,120
Speaker 1: Is it like gobbling up stuff from the Solar system?

669
00:30:44,440 --> 00:30:46,520
Speaker 1: I mean early days you can think of all sorts

670
00:30:46,560 --> 00:30:49,200
Speaker 1: of crazy ideas, right, Yeah, but that was ruled out

671
00:30:49,200 --> 00:30:52,560
Speaker 1: pretty quickly because it would require an enormous amount of mass,

672
00:30:52,600 --> 00:30:55,400
Speaker 1: Like you'd need a sun to refuel the Sun every

673
00:30:55,560 --> 00:30:57,720
Speaker 1: ten thousand years, so it's like the Sun is not

674
00:30:57,800 --> 00:31:01,280
Speaker 1: eating other stars every day. That would leave a huge

675
00:31:01,320 --> 00:31:03,560
Speaker 1: imprint on the orbits of planets and stuff like that,

676
00:31:03,880 --> 00:31:06,520
Speaker 1: so that was ruled out. Another thought people had is

677
00:31:06,840 --> 00:31:10,960
Speaker 1: maybe the Sun is like contracting gravitationally and converting that

678
00:31:11,040 --> 00:31:15,000
Speaker 1: gravitational potential energy somehow into heat. And this is sort

679
00:31:15,000 --> 00:31:17,600
Speaker 1: of on the right track, but if you don't understand fusion,

680
00:31:17,760 --> 00:31:19,760
Speaker 1: you don't have the final piece there. And this would

681
00:31:19,760 --> 00:31:22,240
Speaker 1: only few the star for like tens of millions of years.

682
00:31:22,680 --> 00:31:25,400
Speaker 1: And this is actually what's happening to neutron stars and

683
00:31:25,440 --> 00:31:28,000
Speaker 1: white dwarves that are not undergoing fusion. They're just like

684
00:31:28,280 --> 00:31:30,760
Speaker 1: being compressed and kept hot by gravity.

685
00:31:31,080 --> 00:31:33,520
Speaker 2: Was this Kelvin's idea? All these because it matches up

686
00:31:33,520 --> 00:31:35,240
Speaker 2: with his other All of these were Kelvins.

687
00:31:35,320 --> 00:31:38,000
Speaker 1: These are Calvin's ideas. Yeah, this is Kelvin, like, you know,

688
00:31:38,080 --> 00:31:41,040
Speaker 1: smoking whatever he was smoking and thinking about the universe

689
00:31:41,120 --> 00:31:43,120
Speaker 1: and coming up with dumbers Okay, I love it. I'm

690
00:31:43,160 --> 00:31:43,840
Speaker 1: a fan of Kelvin.

691
00:31:43,920 --> 00:31:45,840
Speaker 2: Yeah, he sounds like a fun guy, and I think

692
00:31:45,880 --> 00:31:48,840
Speaker 2: it would have been fun to read your theories about

693
00:31:48,880 --> 00:31:50,800
Speaker 2: this kind of stuff. And then I could have called

694
00:31:50,840 --> 00:31:52,720
Speaker 2: you not quite rights.

695
00:31:52,360 --> 00:32:00,640
Speaker 1: In, Oh nice, Daniel wrongs and Daniel first a terrible approximation.

696
00:32:00,320 --> 00:32:02,720
Speaker 2: Of the answer that doesn't roll off the tone quite

697
00:32:02,720 --> 00:32:05,160
Speaker 2: as nicely. But okay, what else did Calvin think?

698
00:32:05,520 --> 00:32:08,000
Speaker 1: So that's where the mystery stood until around the early

699
00:32:08,080 --> 00:32:11,840
Speaker 1: nineteen hundreds, And at that point people sort of naturally

700
00:32:11,920 --> 00:32:14,000
Speaker 1: assumed that the Sun must be made of the same

701
00:32:14,000 --> 00:32:16,480
Speaker 1: stuff as the Earth. They were like, hey, the solar

702
00:32:16,480 --> 00:32:20,280
Speaker 1: system comes together, stuff is formed. Why wouldn't the Sun

703
00:32:20,560 --> 00:32:22,959
Speaker 1: be made of the same stuff as the Earth? And

704
00:32:23,240 --> 00:32:24,720
Speaker 1: you know, I think this goes a long way to

705
00:32:24,760 --> 00:32:28,680
Speaker 1: pointing out how often we accept ideas in science because

706
00:32:28,720 --> 00:32:32,320
Speaker 1: they make sense to us without really interrogating them. You know,

707
00:32:32,400 --> 00:32:35,600
Speaker 1: what seems natural doesn't always get as many questions as

708
00:32:35,640 --> 00:32:39,120
Speaker 1: what seems weird, And so later on, one hundred years later,

709
00:32:39,160 --> 00:32:41,800
Speaker 1: when something else seems natural, we might wonder like, huh,

710
00:32:41,880 --> 00:32:44,280
Speaker 1: how could they accept that? But at the time it

711
00:32:44,320 --> 00:32:47,240
Speaker 1: was the most natural explanation, And now is the time

712
00:32:47,280 --> 00:32:50,320
Speaker 1: to enter the major villain of this story, Henry Russell.

713
00:32:51,400 --> 00:32:55,280
Speaker 1: In nineteen fourteen, he wrote, if the Earth's crust should

714
00:32:55,320 --> 00:32:57,720
Speaker 1: be raised to the temperature of the Sun's atmosphere, it

715
00:32:57,720 --> 00:33:01,120
Speaker 1: would give a very similar absorption spectrum. The spectrum of

716
00:33:01,120 --> 00:33:03,200
Speaker 1: the Sun and other stars are similar, so it appears

717
00:33:03,240 --> 00:33:06,400
Speaker 1: that the relative abundance of elements in the universe was

718
00:33:06,560 --> 00:33:09,600
Speaker 1: like that in the Earth's crust. So he's saying the

719
00:33:09,640 --> 00:33:11,760
Speaker 1: Sun is made out of the same stuff as the Earth,

720
00:33:12,080 --> 00:33:13,880
Speaker 1: and if you heat it up the Earth it would

721
00:33:13,920 --> 00:33:15,320
Speaker 1: glow just like the Sun.

722
00:33:15,800 --> 00:33:19,080
Speaker 2: So that sounds wrong, but not villainous. What are we

723
00:33:19,120 --> 00:33:20,880
Speaker 2: going to get to more? Or do you just really

724
00:33:20,880 --> 00:33:22,080
Speaker 2: thought this idea was dumb.

725
00:33:22,280 --> 00:33:24,120
Speaker 1: That's not his villainy, that was just foreshadowing.

726
00:33:24,320 --> 00:33:27,080
Speaker 2: Oh okay, let's take a break and when we come back,

727
00:33:27,120 --> 00:33:51,240
Speaker 2: we'll find out what made Russell villainous. All right, Daniel,

728
00:33:51,240 --> 00:33:53,920
Speaker 2: I'm on pins and needles. Let's get to the story

729
00:33:53,960 --> 00:33:55,560
Speaker 2: of why Russell was such a villain.

730
00:33:56,320 --> 00:33:58,840
Speaker 1: So Russell was on the right track and trying to

731
00:33:58,920 --> 00:34:00,960
Speaker 1: understand what the Sun is made out of, and many

732
00:34:00,960 --> 00:34:04,000
Speaker 1: of our listeners gave this answer. The answer is spectroscopy,

733
00:34:04,200 --> 00:34:06,640
Speaker 1: Like if you can't go there. What can you do

734
00:34:06,720 --> 00:34:08,759
Speaker 1: to understand what something is made out of? And it's

735
00:34:08,760 --> 00:34:10,840
Speaker 1: similar to what you might do on Earth as you mentioned,

736
00:34:10,880 --> 00:34:13,120
Speaker 1: like if you needed to know what is a scoop

737
00:34:13,160 --> 00:34:15,440
Speaker 1: of dirt made out of, you might try to separate

738
00:34:15,480 --> 00:34:17,480
Speaker 1: into components and then you might heat them up and

739
00:34:17,520 --> 00:34:20,080
Speaker 1: look at the light that they emit. Because different atoms

740
00:34:20,120 --> 00:34:24,160
Speaker 1: emit at different wavelengths. Right, every atom has different energy levels.

741
00:34:24,239 --> 00:34:26,480
Speaker 1: The electrons can be on those energy levels, but not

742
00:34:26,600 --> 00:34:29,040
Speaker 1: between them. If you heat it up, the electrons go

743
00:34:29,160 --> 00:34:31,680
Speaker 1: up energy levels. If you let it cool down, the

744
00:34:31,680 --> 00:34:35,320
Speaker 1: electrons go down energy levels and emit photons. The energy

745
00:34:35,360 --> 00:34:39,280
Speaker 1: of those photons matches the energy difference between those energy

746
00:34:39,320 --> 00:34:42,200
Speaker 1: levels and tells you what is the difference between those

747
00:34:42,280 --> 00:34:45,160
Speaker 1: energy levels. And every atom has a different set of energies,

748
00:34:45,200 --> 00:34:47,960
Speaker 1: so every atom has a different spectrum. So you take

749
00:34:48,000 --> 00:34:50,040
Speaker 1: a gas of random stuff, you don't know what it is,

750
00:34:50,080 --> 00:34:52,400
Speaker 1: you heat it up, you look at the energy levels.

751
00:34:52,640 --> 00:34:54,840
Speaker 1: You can figure out what it's made out of and

752
00:34:54,880 --> 00:34:57,480
Speaker 1: what the relative contributions are. You're like, oh, there's a

753
00:34:57,520 --> 00:35:00,279
Speaker 1: little I see hydrogen in here, I see helium here,

754
00:35:00,320 --> 00:35:03,040
Speaker 1: I see lithium or magnesium right, it's an amazing way

755
00:35:03,080 --> 00:35:04,960
Speaker 1: to tell what Earth is made out of. So, in

756
00:35:05,040 --> 00:35:07,440
Speaker 1: terms of the general approach to the listeners and the

757
00:35:07,520 --> 00:35:10,959
Speaker 1: villain of today's episode, Henry Russell, are on the right track.

758
00:35:11,000 --> 00:35:12,920
Speaker 1: The spectroscopy is the way to go.

759
00:35:13,400 --> 00:35:17,600
Speaker 2: He didn't develop spectroscopy, right, he just applied it incorrectly.

760
00:35:17,840 --> 00:35:20,400
Speaker 1: That's right. He didn't develop spectroscopy. And you notice in

761
00:35:20,400 --> 00:35:23,400
Speaker 1: his quote he says if the Earth's crust should be raised,

762
00:35:23,440 --> 00:35:26,120
Speaker 1: it would give a very similar absorption spectrum. And so

763
00:35:26,160 --> 00:35:29,239
Speaker 1: he's sort of speculating here, right, And the problem is

764
00:35:29,280 --> 00:35:31,640
Speaker 1: that this wasn't as easy as we describe it. There

765
00:35:31,680 --> 00:35:36,719
Speaker 1: was an important complexifying factor here, which is ionization. And

766
00:35:36,840 --> 00:35:38,799
Speaker 1: so for example, you might think, well, why don't they

767
00:35:38,800 --> 00:35:40,200
Speaker 1: just look at the light from the Sun and you

768
00:35:40,280 --> 00:35:41,719
Speaker 1: use that to figure out what the Sun is made of?

769
00:35:41,719 --> 00:35:44,160
Speaker 1: Boom boom boom. Done right. Well, the problem is the

770
00:35:44,200 --> 00:35:46,600
Speaker 1: atmosphere of the Sun is complicated, and there's one more

771
00:35:46,640 --> 00:35:49,839
Speaker 1: factor we didn't describe, which is that the atmosphere is ionized.

772
00:35:50,200 --> 00:35:53,120
Speaker 1: Like sometimes these gases in the Sun's atmosphere gets so

773
00:35:53,200 --> 00:35:56,160
Speaker 1: much energy they lose electrons. It's not just like, oh,

774
00:35:56,200 --> 00:35:58,080
Speaker 1: you've got oxygen and has all of its electrons and

775
00:35:58,120 --> 00:36:00,399
Speaker 1: they're going up and down and emitting photons can tell

776
00:36:00,480 --> 00:36:04,520
Speaker 1: it's oxygen. Sometimes those electrons are lost, right, and when

777
00:36:04,560 --> 00:36:07,520
Speaker 1: an atom gets ionized, its energy levels shift a little bit.

778
00:36:07,920 --> 00:36:11,200
Speaker 1: Because it's a big complicated thing, and so the spectrum

779
00:36:11,200 --> 00:36:14,719
Speaker 1: you expect from a star depends on how many electrons

780
00:36:14,800 --> 00:36:18,080
Speaker 1: are around those nuclei, which depends a little bit on

781
00:36:18,120 --> 00:36:20,759
Speaker 1: the temperature of the gas. So it turns out to

782
00:36:20,760 --> 00:36:22,360
Speaker 1: be kind of a complex problem.

783
00:36:22,600 --> 00:36:25,400
Speaker 2: So does that mean that the spectroscopy results from the

784
00:36:25,400 --> 00:36:28,440
Speaker 2: sun were wrong? And he didn't realize that, and that

785
00:36:28,560 --> 00:36:30,040
Speaker 2: was the main problem.

786
00:36:29,880 --> 00:36:32,719
Speaker 1: The spectroscopy results from the Sun. Nobody could understand yet.

787
00:36:32,840 --> 00:36:34,920
Speaker 1: They were like, hmm, this is weird. We don't understand

788
00:36:35,000 --> 00:36:37,200
Speaker 1: these lines. They look different from what we expect. But

789
00:36:37,280 --> 00:36:40,680
Speaker 1: Russell was convinced anyway that it was made of the

790
00:36:40,719 --> 00:36:42,840
Speaker 1: same stuff of the Earth. He believed that it was natural.

791
00:36:42,880 --> 00:36:44,600
Speaker 1: To him. He was like, I'm sure this is just

792
00:36:44,640 --> 00:36:48,319
Speaker 1: some detail. We'll figure this out. And so now enter

793
00:36:48,400 --> 00:36:52,879
Speaker 1: the heroine of this episode. Yes, Cecilia Pain. Cecilia Pain

794
00:36:52,960 --> 00:36:55,600
Speaker 1: is the one who solved this problem. She read a

795
00:36:55,640 --> 00:36:59,680
Speaker 1: paper by a brilliant guy named Megnad Saha, who understood

796
00:36:59,719 --> 00:37:02,680
Speaker 1: all the these ionization effects. He like calculated exactly what you

797
00:37:02,680 --> 00:37:05,839
Speaker 1: should expect for various ionizations at various temperatures of all

798
00:37:05,880 --> 00:37:08,319
Speaker 1: of the elements. He was just like, he wasn't thinking

799
00:37:08,320 --> 00:37:10,279
Speaker 1: about the Sun. He was just like, Hey, chemistry is cool,

800
00:37:10,280 --> 00:37:12,239
Speaker 1: and I want to understand energy levels and let's dig

801
00:37:12,280 --> 00:37:14,839
Speaker 1: deep into this. And he totally nerded out about this.

802
00:37:15,360 --> 00:37:18,080
Speaker 1: And Cecily Pain is like, oh, this is a solution

803
00:37:18,200 --> 00:37:20,919
Speaker 1: to this huge problem that we have over in astrophysics

804
00:37:20,920 --> 00:37:23,759
Speaker 1: of understanding what we should expect from the sun. So

805
00:37:23,800 --> 00:37:26,240
Speaker 1: she put these two things together and she was able

806
00:37:26,280 --> 00:37:29,440
Speaker 1: to interpret correctly the spectrum of light we're getting from

807
00:37:29,480 --> 00:37:32,160
Speaker 1: the Sun and understand why it looked a little shifted

808
00:37:32,200 --> 00:37:35,240
Speaker 1: and a little weird from what folks like Henry Russell expected.

809
00:37:35,640 --> 00:37:39,920
Speaker 2: Amazing, and like note students, the importance of reading widely.

810
00:37:40,800 --> 00:37:42,719
Speaker 2: I think there are so many connections that you make

811
00:37:42,760 --> 00:37:44,000
Speaker 2: that you might not be expecting.

812
00:37:44,400 --> 00:37:47,640
Speaker 1: Yeah, exactly, And so this is a huge breakthrough and like,

813
00:37:47,719 --> 00:37:50,000
Speaker 1: finally we could understand what the sun is made out of.

814
00:37:50,200 --> 00:37:53,120
Speaker 1: And the result was a huge surprise, especially to folks

815
00:37:53,239 --> 00:37:56,160
Speaker 1: like Pain. Number one, the sun is made out of

816
00:37:56,160 --> 00:37:59,320
Speaker 1: the same stuff as the Earth, Like there's hydrogen in this, helium,

817
00:37:59,320 --> 00:38:01,800
Speaker 1: this oxygen, iron, this nickel, this all the same stuff,

818
00:38:01,920 --> 00:38:05,320
Speaker 1: but it comes in very different numbers. Like the relative

819
00:38:05,360 --> 00:38:08,920
Speaker 1: abundances are very very different in the Sun. Basically the

820
00:38:08,960 --> 00:38:12,920
Speaker 1: Sun is mostly hydrogen and helium and everything else is there,

821
00:38:13,120 --> 00:38:17,400
Speaker 1: but it's tiny, Like it's seventy four percent hydrogen, twenty

822
00:38:17,400 --> 00:38:20,880
Speaker 1: five percent helium, and everything else is one percent.

823
00:38:21,440 --> 00:38:24,080
Speaker 2: Wow. Yeah, all right, And so I'm just gonna guess,

824
00:38:24,480 --> 00:38:27,320
Speaker 2: based on some other conversations we've had about women in science,

825
00:38:27,600 --> 00:38:30,800
Speaker 2: that Russell isn't just the villain because he was wrong,

826
00:38:31,400 --> 00:38:34,879
Speaker 2: but he probably did something to turf Pain's results. Am

827
00:38:34,880 --> 00:38:35,200
Speaker 2: I right?

828
00:38:35,280 --> 00:38:36,080
Speaker 1: Oh? Absolutely?

829
00:38:36,239 --> 00:38:36,520
Speaker 2: Okay.

830
00:38:36,680 --> 00:38:39,239
Speaker 1: So she was at Harvard and the director of the

831
00:38:39,280 --> 00:38:42,920
Speaker 1: observatory was Russell, and Russell had the power at the

832
00:38:42,960 --> 00:38:46,600
Speaker 1: time to veto any publication he wanted for whatever reason,

833
00:38:47,040 --> 00:38:51,200
Speaker 1: including her thesis. Aw So he blocked her getting her

834
00:38:51,200 --> 00:38:54,759
Speaker 1: PhD thesis unless she added the following caveat to her

835
00:38:54,800 --> 00:38:59,840
Speaker 1: thesis quote. The outstanding discrepancy between the astrophysical and to

836
00:39:00,040 --> 00:39:04,120
Speaker 1: rrestrial abundances are displayed for hydrogen and helium. The enormous

837
00:39:04,120 --> 00:39:07,360
Speaker 1: abundance derived for these elements in the atmosphere is almost

838
00:39:07,560 --> 00:39:08,720
Speaker 1: certainly not real.

839
00:39:09,040 --> 00:39:11,440
Speaker 2: What he had her at a caveat that was like,

840
00:39:11,480 --> 00:39:12,719
Speaker 2: but also, probably I'm wrong.

841
00:39:13,480 --> 00:39:16,560
Speaker 1: Is all this amazing science is huge breakthrough and then

842
00:39:16,600 --> 00:39:19,120
Speaker 1: he's like, I disagree with it, so probably this is BS.

843
00:39:19,160 --> 00:39:20,200
Speaker 1: Don't believe these numbers.

844
00:39:20,280 --> 00:39:23,680
Speaker 2: By the way, Oh my gosh. And what a coward

845
00:39:23,719 --> 00:39:26,800
Speaker 2: that he did. Sounds like he didn't point out exactly

846
00:39:26,840 --> 00:39:29,400
Speaker 2: where she had an error right, like because.

847
00:39:30,160 --> 00:39:32,360
Speaker 1: He just couldn't accept it. He was like, no, the

848
00:39:32,400 --> 00:39:35,120
Speaker 1: science says, so I don't see a mistake, but no,

849
00:39:35,320 --> 00:39:37,160
Speaker 1: this flies in the face of what I believe, and

850
00:39:37,239 --> 00:39:41,000
Speaker 1: so I'm gonna insist that you add this caveat to

851
00:39:41,080 --> 00:39:44,120
Speaker 1: her thesis. Her advisor was a guy named Harlow Shapley

852
00:39:44,520 --> 00:39:47,080
Speaker 1: and shapely ordered six hundred copies of her thesis and

853
00:39:47,160 --> 00:39:49,720
Speaker 1: sent it to all the important astronomers in the world.

854
00:39:49,840 --> 00:39:51,640
Speaker 2: Oh wow, okay, so he believed in her.

855
00:39:51,960 --> 00:39:54,200
Speaker 1: He believed in her. Yet did he go through exactly.

856
00:39:54,000 --> 00:39:56,680
Speaker 2: All six hundred copies and like cross out that line

857
00:39:56,719 --> 00:39:57,680
Speaker 2: that she had to add.

858
00:39:59,000 --> 00:40:00,760
Speaker 1: I don't know, but he knew this guy because Russell

859
00:40:00,840 --> 00:40:03,520
Speaker 1: was also his PhD advisor. So I think they had

860
00:40:03,520 --> 00:40:06,880
Speaker 1: a common experience there. But it gets even worse because

861
00:40:06,960 --> 00:40:10,280
Speaker 1: even though Russell said no, this isn't true, this can't

862
00:40:10,320 --> 00:40:13,760
Speaker 1: be true, a few years later, when the scientific tides

863
00:40:13,840 --> 00:40:19,720
Speaker 1: turned and everybody accepted this, he took credit for this discovery. No, yes, exactly,

864
00:40:19,800 --> 00:40:23,879
Speaker 1: And so in most historical records until recently, people gave

865
00:40:23,960 --> 00:40:26,680
Speaker 1: Henry Russell credit for a discovery of what the sun

866
00:40:26,760 --> 00:40:29,280
Speaker 1: is made out of, which is like such a tragedy.

867
00:40:29,520 --> 00:40:32,040
Speaker 2: No it is, I agree, it's exactly.

868
00:40:32,239 --> 00:40:35,160
Speaker 1: He's a total villain. So only four years after calling

869
00:40:35,160 --> 00:40:38,320
Speaker 1: it impossible, you find him in the literature taking credit

870
00:40:38,360 --> 00:40:40,800
Speaker 1: for this discovery. So it's a real shame.

871
00:40:41,080 --> 00:40:43,440
Speaker 2: It isn't real. Okay, So then how did we rediscover

872
00:40:43,560 --> 00:40:44,359
Speaker 2: Cecilia Paine?

873
00:40:44,400 --> 00:40:44,560
Speaker 3: Then?

874
00:40:44,760 --> 00:40:47,479
Speaker 1: Yeah, that's an important point. Cecia Paine ended up getting

875
00:40:47,520 --> 00:40:50,719
Speaker 1: her PhD in astronomy, only the second PhD in astronomy

876
00:40:50,719 --> 00:40:53,279
Speaker 1: ever by a woman at Harvard WOW. And initially she

877
00:40:53,440 --> 00:40:55,640
Speaker 1: was barred from becoming a professor at Harvard because she

878
00:40:55,680 --> 00:40:58,480
Speaker 1: was a woman, so she did a lot of less prestigious,

879
00:40:58,520 --> 00:41:01,759
Speaker 1: lower paid research job, but she ended up becoming the

880
00:41:01,800 --> 00:41:04,840
Speaker 1: first female tenured professor at Harvard WOW, and the first

881
00:41:04,840 --> 00:41:06,960
Speaker 1: female chair of a department at Harvard.

882
00:41:07,040 --> 00:41:07,239
Speaker 4: Wow.

883
00:41:07,440 --> 00:41:10,720
Speaker 1: So you know, things changed and she ended up having

884
00:41:10,760 --> 00:41:14,400
Speaker 1: a good career in astrophysics. And then later people digging

885
00:41:14,400 --> 00:41:17,560
Speaker 1: into the record corrected it, and so, for example, there

886
00:41:17,640 --> 00:41:20,320
Speaker 1: is an essay by Otto Struve who called it quote

887
00:41:20,880 --> 00:41:24,799
Speaker 1: undoubtedly the most brilliant Pahd thesis ever written in astronomy.

888
00:41:24,920 --> 00:41:25,400
Speaker 2: Wow.

889
00:41:25,480 --> 00:41:30,880
Speaker 1: Wow, that's forty years later. She went forty years before

890
00:41:31,000 --> 00:41:32,360
Speaker 1: really getting the recognition.

891
00:41:32,760 --> 00:41:34,320
Speaker 2: Was she still alive, Yeah, she was.

892
00:41:34,760 --> 00:41:36,239
Speaker 1: She died in seventy nine.

893
00:41:36,520 --> 00:41:38,719
Speaker 2: I'm glad she got to see her work vindicated in

894
00:41:38,719 --> 00:41:39,920
Speaker 2: her lifetime. That's amazing.

895
00:41:40,120 --> 00:41:42,240
Speaker 1: Yeah. She ended up winning some prizes and was elected

896
00:41:42,239 --> 00:41:46,000
Speaker 1: to the Royal Astronomical Society. The arc of justice is long,

897
00:41:46,120 --> 00:41:48,799
Speaker 1: but it does point in the right direction, even into astronomy.

898
00:41:48,960 --> 00:41:50,840
Speaker 2: I mean often, but not.

899
00:41:50,719 --> 00:41:54,319
Speaker 1: Always eventually, I hope, yes. But to see it, pain

900
00:41:54,400 --> 00:41:56,840
Speaker 1: taught us a lot about the nature of the universe, right.

901
00:41:56,920 --> 00:41:59,759
Speaker 1: People thought for a long time that everything in the

902
00:42:00,120 --> 00:42:01,799
Speaker 1: verse must be made out of the same stuff as

903
00:42:01,800 --> 00:42:04,000
Speaker 1: the Earth, like that was a natural assumption to them.

904
00:42:04,320 --> 00:42:06,200
Speaker 1: And now we know, of course that the Sun is

905
00:42:06,360 --> 00:42:09,640
Speaker 1: mostly hydrogen and helium, and from our models of the

906
00:42:09,640 --> 00:42:12,440
Speaker 1: formation of the solar system. It makes sense, right, Like

907
00:42:12,760 --> 00:42:15,440
Speaker 1: the Sun is the center of gravity and most stuff

908
00:42:15,400 --> 00:42:17,799
Speaker 1: flocks there and it pulls in all the gases in

909
00:42:17,840 --> 00:42:20,399
Speaker 1: the inner Solar System, and the Earth did have more

910
00:42:20,480 --> 00:42:23,760
Speaker 1: hydrogen helium early on, but because these are such light elements,

911
00:42:23,760 --> 00:42:26,719
Speaker 1: they were blasted away by the Sun's radiation in the

912
00:42:26,719 --> 00:42:29,040
Speaker 1: early part of the formation of the Solar System. So

913
00:42:29,080 --> 00:42:31,920
Speaker 1: now we have a full and complex and nuanced understanding

914
00:42:32,280 --> 00:42:34,520
Speaker 1: of the formation of the Solar System and the planets,

915
00:42:34,640 --> 00:42:37,759
Speaker 1: and we can apply this knowledge to understanding other stars,

916
00:42:37,800 --> 00:42:40,000
Speaker 1: like our star isn't the only star in the universe,

917
00:42:40,040 --> 00:42:43,000
Speaker 1: and every star has its own unique pattern. We talked

918
00:42:43,000 --> 00:42:45,920
Speaker 1: recently about why stars are different colors because they are

919
00:42:45,960 --> 00:42:48,360
Speaker 1: made of different stuff, and their atmospheres has different stuff

920
00:42:48,360 --> 00:42:51,120
Speaker 1: and they're different temperatures. And now with this model, with

921
00:42:51,160 --> 00:42:53,960
Speaker 1: to see a pain's understanding, we can use this to

922
00:42:54,040 --> 00:42:56,440
Speaker 1: understand what the rest of the universe is made out of.

923
00:42:57,040 --> 00:42:59,480
Speaker 2: Wow, Okay, And so with these corrections we can now

924
00:42:59,640 --> 00:43:02,520
Speaker 2: look at out into the universe and without even visiting it,

925
00:43:02,600 --> 00:43:05,080
Speaker 2: we can know what different celestial bodies are made out of.

926
00:43:05,840 --> 00:43:09,440
Speaker 1: Yeah, exactly. Thanks to Secila opinion and to Megna Saha,

927
00:43:09,560 --> 00:43:12,960
Speaker 1: he is an Indian astrophysicist who figured out the ionization equations.

928
00:43:13,000 --> 00:43:16,440
Speaker 1: His Saha ionization equation is super important for us to

929
00:43:16,480 --> 00:43:19,600
Speaker 1: figure out the nature of the universe. And it's incredible

930
00:43:19,640 --> 00:43:21,680
Speaker 1: that we can figure this out. I mean, think about

931
00:43:21,719 --> 00:43:24,440
Speaker 1: all the little puzzles that people had to solve all

932
00:43:24,480 --> 00:43:26,840
Speaker 1: the way down to like figuring out how massive the

933
00:43:26,880 --> 00:43:30,080
Speaker 1: Earth is by measuring a mountain in Scotland. Like, all

934
00:43:30,120 --> 00:43:32,840
Speaker 1: of these pieces were necessary and they all came together.

935
00:43:33,280 --> 00:43:35,600
Speaker 1: And when you're solving a puzzle, often there's like a

936
00:43:35,680 --> 00:43:38,640
Speaker 1: huge unanswered question that you don't even know how to begin.

937
00:43:38,800 --> 00:43:40,920
Speaker 1: And if you're lucky, people have been working on that

938
00:43:41,000 --> 00:43:44,520
Speaker 1: question for other reasons for one hundreds of years, making progress,

939
00:43:44,640 --> 00:43:47,120
Speaker 1: hiking around mountains trying to figure it out, or just

940
00:43:47,160 --> 00:43:50,280
Speaker 1: nerding out about the chemistry. But sometimes you're not so lucky.

941
00:43:50,440 --> 00:43:52,279
Speaker 1: And that's why it's so important that we push in

942
00:43:52,400 --> 00:43:55,520
Speaker 1: so many directions simultaneously, even though we don't know yet

943
00:43:55,760 --> 00:43:58,160
Speaker 1: how they're going to be useful or what mysteries they

944
00:43:58,239 --> 00:44:00,960
Speaker 1: might unlock. We need all of these tools so that

945
00:44:01,080 --> 00:44:03,320
Speaker 1: in the future, clever people can come up with answers

946
00:44:03,600 --> 00:44:06,360
Speaker 1: to huge questions like what is the universe?

947
00:44:06,480 --> 00:44:09,520
Speaker 2: Made out of amen. By geeking out and by geeking

948
00:44:09,560 --> 00:44:11,680
Speaker 2: out together, we can change the world.

949
00:44:13,520 --> 00:44:15,359
Speaker 1: All right. Thanks very much for coming on this tour

950
00:44:15,440 --> 00:44:18,080
Speaker 1: of how we figured out what elements of the universe

951
00:44:18,280 --> 00:44:20,640
Speaker 1: is made out of diving deep into the earth and

952
00:44:20,680 --> 00:44:23,120
Speaker 1: casting our minds all the way across the universe.

953
00:44:30,080 --> 00:44:33,920
Speaker 2: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We

954
00:44:33,960 --> 00:44:35,359
Speaker 2: would love to hear from you.

955
00:44:35,480 --> 00:44:38,400
Speaker 1: We really would. We want to know what questions you

956
00:44:38,640 --> 00:44:41,280
Speaker 1: have about this Extraordinary Universe.

957
00:44:41,360 --> 00:44:44,320
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958
00:44:44,320 --> 00:44:47,319
Speaker 2: for future shows. If you contact us, we will get

959
00:44:47,360 --> 00:44:47,759
Speaker 2: back to you.

960
00:44:48,040 --> 00:44:51,560
Speaker 1: We really mean it. We answer every message. Email us

961
00:44:51,600 --> 00:44:54,799
Speaker 1: at Questions at Danielankelly.

962
00:44:53,880 --> 00:44:55,960
Speaker 2: Dot org, or you can find us on social media.

963
00:44:56,040 --> 00:44:59,799
Speaker 2: We have accounts on x, Instagram, Blue Sky and on

964
00:45:00,040 --> 00:45:01,920
Speaker 2: all of those platforms. You can find us at D

965
00:45:02,320 --> 00:45:03,840
Speaker 2: and K Universe.

966
00:45:04,040 --> 00:45:05,600
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