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Speaker 1: Hey, or Hey, how's your dad band going?

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Speaker 2: Uh? Pretty good? Yeah, we're getting better. It's a lot

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Speaker 2: of fun, didn't you guys have some clever name, sort

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Speaker 2: of clever. We call ourselves the Grateful Dads.

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Speaker 1: And is that the kind of music you play? Psychedelic

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Speaker 1: sixties rock or are you more like alternative or metal?

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Speaker 2: We play a little bit of everything, you know, Eighties music,

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Speaker 2: nineties rock, some Marvin Gaye, some Pink Floyd, a little bit.

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Speaker 1: Of all right. So then the physicist in me wants

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Speaker 1: to know how metal are you guys?

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Speaker 2: I would say we're less and Iron Maiden, maybe more

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Speaker 2: than the Doobie Brothers.

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Speaker 1: That sounds like it leaves a lot of uncertainty.

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Speaker 2: That's for sure. We always try to rocket.

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Speaker 1: Hi.

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Speaker 2: I'm Horem and Cartoonez and the author of Oliver's Great

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Speaker 2: Big Universe.

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

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Speaker 1: at UC Irvine, and I like music with all different

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Speaker 1: kinds of metal.

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Speaker 2: You mean, like the instruments or like the genre the genre?

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Speaker 1: You know, A little heavy metal, little light metal? Is

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Speaker 1: light metal even a thing?

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Speaker 2: M I think some of these heavy metal groups have

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Speaker 2: saw songs. Does that still count as metal.

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Speaker 1: I'm not even going to weigh in on that.

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Speaker 2: Yeah, we don't want to anger those metal people. M

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Speaker 2: they're pretty intense. But anyways, Welcome to our podcast Daniel

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Speaker 2: and Jorge Explain the Universe, a production of iHeartRadio.

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Speaker 1: In which we attempt to understand everything in the universe,

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Speaker 1: from the tiny quantum particles to the amazing shiny metals

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Speaker 1: that make up our universe. We want to know how

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Speaker 1: everything in the universe functions. We want to know what

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Speaker 1: its smallest bits are and how they come together to

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Speaker 1: explain everything in our amazing, crazy, delicious and bonkers universe.

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Speaker 2: That's right, because the universe is made out of all

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Speaker 2: kinds of things, and in this podcast we'd like to

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Speaker 2: explore all of it and to figure out what it's

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Speaker 2: all made out of, how it's all put together, and

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Speaker 2: what makes things the way they are.

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Speaker 1: How you can go from quantum particles to dad bands

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Speaker 1: in Pasadena or marching bands in New Mexico. The only

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Speaker 1: kind of band I've ever been in.

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Speaker 2: And did you play metal or did you play a

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Speaker 2: metal instrument?

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Speaker 1: Not even I played the totally unhearable instrument, the clarinet. Oh,

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Speaker 1: you can only hear the clarinet in the marching band

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Speaker 1: if you're literally in the middle of the clarinet section.

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Speaker 1: Otherwise it's just trumpets.

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Speaker 2: But the clarinet is made out of metal, isn't it?

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Speaker 2: Or is that one of the woodwinds.

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Speaker 1: It's a woodwind, though there are metal bits of course

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Speaker 1: to operate the holes.

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Speaker 2: And what kind of music did you guys play?

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Speaker 1: Oh? You know, we played marching band versions of all

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Speaker 1: your greatest.

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Speaker 2: Hits, including metal songs, including metal songs.

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Speaker 1: Absolutely, there's a marching band version of every song you love,

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Speaker 1: and we ruin it.

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Speaker 2: Maybe you should start a band with physicists.

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Speaker 1: What would we call it?

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Speaker 2: I don't know what would you call it?

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Speaker 1: Maybe some Higgs Boson reference. We make everything heavy?

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Speaker 2: How about you too have mass?

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Speaker 1: That's pretty good?

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Speaker 2: Or how about the clash of particles?

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Speaker 1: All right, now, I just need some musical talents that

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Speaker 1: I'm all set.

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Speaker 2: How about the doov Boson brothers?

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Speaker 1: All right? I think we're good on band names.

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Speaker 2: But yeah, it is interesting to think about all the

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Speaker 2: things that the stuff in the universe is made out of, right.

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Speaker 1: It is really interesting. It's fascinating to understand how all

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Speaker 1: that stuff got made and how it comes together to

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Speaker 1: make our universe, because even the tiniest little bits of

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Speaker 1: metal here and there are required, absolutely essential for the

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Speaker 1: universe to operate the way that it does.

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Speaker 2: Yeah, Because the universe, I guess, is made out of

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Speaker 2: all kinds of things, gases, solids, liquids, metals, non metals, acids, bases.

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Speaker 2: There's all kinds of ways that you can categorize the

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Speaker 2: stuff that stuff is made out of, right.

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Speaker 1: Yeah, absolutely, And though it's all made out of the

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Speaker 1: same fundamental bits. You take quarks and you mix them

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Speaker 1: together to make protons and neutrons, you add electrons. Those

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Speaker 1: few little ingredients can make all kinds of things out

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Speaker 1: there in the universe, with all kinds of different behaviors.

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Speaker 1: Some of them conduct electricity, some of them don't. Some

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Speaker 1: of them are strong, some of them are brittle, some

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Speaker 1: of them are soft, some of them interact, and some

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Speaker 1: of them don't. It's incredible the variety of stuff you

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Speaker 1: can make with just a few basic bits.

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Speaker 2: Some of the stuff is soft rock, some of it

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Speaker 2: is classical physics, some of it is heavy metals.

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Speaker 1: Literally, with the same instruments, you can make any kind

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Speaker 1: of music.

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Speaker 2: And with the same kinds of particles. You can make

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Speaker 2: everything that you see out there in the universe, all

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Speaker 2: the different kinds of stuff out there, And sometimes it's

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Speaker 2: kind of surprising all the different kinds of things that

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Speaker 2: we're made out of, right, Like, we're not just made

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Speaker 2: out of carbon and the basic building blocks, but there's

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Speaker 2: a bunch of weird things that it turns out are

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Speaker 2: sort of essential to our living. Right. Our bodies need copper.

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Speaker 1: Yeah, and oxygen for example, and all sorts of bits

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Speaker 1: to take advantage of the clever tricks of chemistry to

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Speaker 1: communicate information along our nerves. To capture oxygen in our

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Speaker 1: red blood cells, you need all sorts of elements. So

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Speaker 1: it's wonderful that these things exist out there in the universe,

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Speaker 1: that they've been somehow manufactured through physics in order to

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Speaker 1: shape our existence.

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Speaker 2: Now, some of us have more or less metal inside

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Speaker 2: of us, right, I mean, I grew up in the eighties,

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Speaker 2: and so my teeth are full of metals, all kinds

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Speaker 2: of metals in there. Absolutely, you got some lead grills.

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Speaker 1: And some of us probably played with mercury as a kid,

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Speaker 1: and so we have more or less mercury in us.

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Speaker 2: Yeah, did you play with Mercury. I play with Mercury

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Speaker 2: all the time, which probably maybe explains a lot.

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Speaker 1: That's why you're in a heavy metal band now, Yeah.

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Speaker 2: Yeah, that's why I'm so Mercuriers. But yeah, it kind

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Speaker 2: of makes you wonder what else the stuff out there

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Speaker 2: in the universe is made out of. You know, even

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Speaker 2: our planet I'm sure is mostly iron and rocks and silica.

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Speaker 2: But the stuff out there in space, what is that

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Speaker 2: made out of?

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Speaker 1: Yeah? Most of the stuff in the Solar System is

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Speaker 1: not us or even the Earth. An overwhelming fraction of

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Speaker 1: the Solar System is basically just the Sun. And of

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Speaker 1: course the Sun is crucial to life on Earth and

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Speaker 1: the operation of the Solar system. So it's in our

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Speaker 1: interest to understand, like, hey, what's in the sun because

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Speaker 1: that affects how long it's going to last and how

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Speaker 1: it behaves.

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Speaker 2: And so today on the podcast, we'll be tackling the

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Speaker 2: question how much metal is in the sun, not how

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Speaker 2: much metal is the sun?

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Speaker 1: How metal is the sun? If it had a dad band,

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Speaker 1: what would it play?

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Speaker 2: Well, we probably play a lot of songs about the sun.

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Speaker 2: You know, here comes the Sun, you are my sunshine.

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Speaker 1: It's opening has to be. Here comes the Sun. Absolutely,

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Speaker 1: that's its walk on music. For sure, that's their theme music.

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Speaker 2: Who would the son being a band with Jupiter, I guess,

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Speaker 2: or other suns?

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Speaker 1: It might outshine Jupiter.

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Speaker 2: Yeah, or maybe it's a solo act. Can you be

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Speaker 2: a solo metal act?

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Speaker 1: Probably you'd have to because nobody wants to be in

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Speaker 1: the Sun's shadow.

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Speaker 2: I think if you're next to the Sun, you're definitely

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Speaker 2: not in the shadow.

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Speaker 1: I know. I love how that joke made no sense.

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Speaker 2: Yeah, I'm trying to save it there, but no, you know,

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Speaker 2: I'm finding the loss of physics here.

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Speaker 1: Daniel, No, I was going for maximum nonsense.

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Speaker 2: Hmm, right, right, was on purpose. There's very metal of you.

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Speaker 2: If he has shouted it out, it would be even

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Speaker 2: more metal.

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Speaker 1: This is a really fascinating topic to me because I

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Speaker 1: love mysteries in our own neighborhood. You know, we wonder

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Speaker 1: about what's going on at the edge of the universe

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Speaker 1: or the beginning of time. But gosh darn it, we

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Speaker 1: haven't even figured out what our own solar system is

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Speaker 1: made out of.

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Speaker 2: We live in it, but we don't know kind of

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Speaker 2: what's in it, what's it all made out of? But

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Speaker 2: it's kind of an interesting question because you're particularly asking

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Speaker 2: how much metal is in the sun, not like what

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Speaker 2: is the sun made out of? Because I guess most

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Speaker 2: of the sun is just one thing, right.

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Speaker 1: Yeah, the sun is mostly hydrogen and a little bit

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Speaker 1: of helium, and what you call the rest is kind

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Speaker 1: of up for debate. I cringe to inform you that

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Speaker 1: it depends on your definition of metal, because in astronomy,

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Speaker 1: metal is anything but hydrogen or helium.

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Speaker 2: Right. I was going to mention that, like, what exactly

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Speaker 2: do you mean by metal? Because the metal means different

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Speaker 2: things to different people, right, yeah, exactly. I feel like

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Speaker 2: to us or to the everyday person, a metal is

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Speaker 2: something that's shiny and hard conducts electricity. Now is that wrong?

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Speaker 1: No, It's totally reasonable to think metals are things that

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Speaker 1: are metallic that have those properties, right, And that's how chemists,

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Speaker 1: for example, use the word metal, But astronomers think about

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Speaker 1: things differently.

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Speaker 2: Wait wait, wait, so is there an official definition of

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Speaker 2: metal by chemists that's different than the definition of metals

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Speaker 2: by physicists.

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Speaker 1: Well, by astronomers in particular, because the condensed matter physicists

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Speaker 1: would agree with the chemists because they're sort of almost

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Speaker 1: on the chemistry side physics. But astronomers, Wow, that's their

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Speaker 1: own community, and you know they got their issues with

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Speaker 1: naming stuff. There's fights about everything.

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Speaker 2: M okay. So then if we're asking how much metal

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Speaker 2: is in the sun, what are we asking like how

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Speaker 2: much non helium and hydrogen is in the sun? Or

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Speaker 2: are we asking how much metallic shining stuff is in

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Speaker 2: the sun?

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Speaker 3: Well?

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Speaker 1: I want to know everything about what's in the sun,

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Speaker 1: like how much iron is there anywhere? And where did

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Speaker 1: it come from? How could iron get into the sun?

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Speaker 1: But we don't even know very well the answer to

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Speaker 1: the more basic question, which is how much non hydrogen

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Speaker 1: and helium is there in the sun? How much astronomy

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Speaker 1: metal is in the sun.

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Speaker 2: Oh okay, so we're really asking the question how much

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Speaker 2: of the sun is not hydrogen or helium?

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Speaker 1: Yeah? Exactly.

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Speaker 2: Can we ask later how much of the sun is

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Speaker 2: the shining metallic stuff.

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Speaker 1: I mean, you're very mercurious, so you're allowed to ask anything.

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Speaker 2: A mercurious said mercurious?

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Speaker 1: Yeah?

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Speaker 2: Is that like a merman? But like a curious merman?

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Speaker 1: Well, you know, I guess you can be bi curious,

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Speaker 1: you can be mercurious. You know, I don't know what

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Speaker 1: that means. I'll let you figure that out. You just

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Speaker 1: want to dive into everything.

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Speaker 2: Yeah, I want to know it at all, but only

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Speaker 2: for a short amount of time. But anyways, how much

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Speaker 2: metal is in the sun, that's an interesting question. How

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Speaker 2: did you come up with this question?

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Speaker 1: Well, I was reading some papers about the mysteries of

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Speaker 1: how much metal is in the sun. I thought it

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Speaker 1: was fascinating that we still don't know the answer to

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Speaker 1: this pretty basic question that influences like the most important

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Speaker 1: thing in our neighborhood.

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Speaker 3: Hmmm.

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Speaker 2: Interesting, And I think also like what's in the sun

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Speaker 2: sort of affects the kind of light that we get

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Speaker 2: from the sun, right, Like you can tell what kinds

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Speaker 2: of things are inside of a star by looking at

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Speaker 2: its light.

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Speaker 1: And it has really cosmic consequences because we use the

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Speaker 1: Sun to calibrate our understanding of what's in the rest

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Speaker 1: of the universe, and the amount of metal in stars

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Speaker 1: controls their fate, like whether they'll collapse into a black

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Speaker 1: hole or not, and also how likely they are to

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Speaker 1: have planets around them. And so if we revise our

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Speaker 1: understanding of what's in the sun, it could change our

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Speaker 1: understand of what's out there in the universe, how long

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Speaker 1: it will last, and the likelihood that there could be aliens.

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Speaker 1: So yeah, in the end, it always connects to aliens.

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Speaker 2: Where did that come from? Is this just a big

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Speaker 2: excuse to talk about aliens again?

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Speaker 1: That's what this whole podcast is. Are you just figuring

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Speaker 1: that out?

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Speaker 2: Yeah, a little bit. Yeah, that we were explaining the universe.

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Speaker 1: It's just a fun for talking about aliens.

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Speaker 2: I see. This is all just a ployed to what

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Speaker 2: prepares us subconsciously for the imminent arrival of aliens or

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Speaker 2: the big reveal that you are an alien?

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Speaker 1: No comment.

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Speaker 2: Yeah, that's very suspicious, all right. So, as usual, we

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Speaker 2: were wondering how many people out there had thought about

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Speaker 2: this question and about the amount of metal in the sun.

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Speaker 1: Thanks very much to everybody who answers these questions. I

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Speaker 1: love hearing your thoughts on the question of the day,

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Speaker 1: so please don't be shy. If you would like to contribute,

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Speaker 1: write to me two questions at Daniel and Jorge dot

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Speaker 1: com and I'll get you on the air.

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Speaker 2: So think about it for a second. How much metal

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Speaker 2: do you think is in the sun. Here's what be

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Speaker 2: bled to say.

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Speaker 1: I think the heavier elements only come out during supernova's

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Speaker 1: and so I would have to say no metal in

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Speaker 1: the Sun.

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Speaker 2: I think that nineteen nine percent of the Solar System's

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Speaker 2: metals allocated in the Sun itself. But with regards to

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Speaker 2: the makeup of the Sun, I think that only about

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Speaker 2: eight percent of it is metal. The rest of it

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Speaker 2: is gas.

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Speaker 1: Most of it is fine.

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Speaker 3: I want to guess not very much right now, like

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Speaker 3: less than one percent. But as the Sun grows older,

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Speaker 3: maybe the amount of metal in the core will increase

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Speaker 3: until the mass becomes so great that the light cannot escape,

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Speaker 3: and then the Sun will turn black.

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Speaker 4: If we measured that diameter of the outer core, I

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Speaker 4: would assume that the metal is like less than like

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Speaker 4: ten percent of like the diameter with But I feel

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Speaker 4: like it's a truck question because don't cosmologists say anything

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Speaker 4: above helium as a metal, so this might be a

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Speaker 4: true question. I'm going to go ninety eight percent metal.

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Speaker 5: The Sun is totally metal, but I think if we're

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Speaker 5: talking about actual companies, there's not all that much. I'm

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Speaker 5: going to guess that the Sun has a little bit

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Speaker 5: of metal, like maybe one or two percent of its

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Speaker 5: total composition, but that's actually considered a lot compared to

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Speaker 5: other stars, and that the stars that came before the

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Speaker 5: sun had even less metal.

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Speaker 2: All right, Like the person who said the sun is

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Speaker 2: totally metal.

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Speaker 1: The sun has a good attitude. I think that's what

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Speaker 1: he means.

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Speaker 2: Yeah, well it is pretty hot, I guess intense.

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Speaker 1: Yeah, it's just not back down. Yeah, it just keeps

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Speaker 1: rocking on and on.

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Speaker 2: Yeah, and it eventually burns up. So that kind of

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Speaker 2: fits the heavy metal rock star.

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Speaker 1: Trope, flaming out as a pretty metal thing to do.

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Speaker 2: Yeah, all right, well, Daniel, maybe start with the basics.

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Speaker 2: How does a star even get metal in it? Because,

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Speaker 2: as we all know, stars are made out of hydrogen,

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Speaker 2: helium or hydrogen initially, right, all stars, or at least

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Speaker 2: the original stars were made out of hydrogen.

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Speaker 1: Yeah, it's a cool question. Stars can get metal in

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Speaker 1: them in two ways. One is that they can be

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Speaker 1: formed with metal in them. Stars come from a collapse

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Speaker 1: of a big cloud of like gas and dust and

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Speaker 1: other bits, So there's metal in the neighborhood. When the

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Speaker 1: star collapses, then that metal will become part of the star.

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Speaker 1: But that depends, as you were alluding to, on what's

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Speaker 1: around what's been made? Has something else out there? Made metal,

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Speaker 1: And the only way that we know to make metal

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Speaker 1: is in the hearts of stars. So the second way

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Speaker 1: that stars can get metal in them is they can

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Speaker 1: make metal. They confuse hydrogen and helium together to make

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Speaker 1: heavier stuff producing metal.

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Speaker 2: I meaning like when a star was formed and it

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Speaker 2: gathered all the gas to become a star, maybe there

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Speaker 2: were metals floating around where all this stuff was, and

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Speaker 2: that's how metal got inside the star. But were the

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Speaker 2: first stars made out of pure hydrogen or that the

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Speaker 2: universe makes a metal at the Big bang?

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Speaker 1: Yeah, great question. So about millions of a second after

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Speaker 1: the sort of primordial do things were expanding and cooling,

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Speaker 1: and you got quarks forming into protons and neutrons and

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Speaker 1: protons are hydrogen, So basically the first thing that made

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Speaker 1: was hydrogen. Because protons form, then you have a few

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Speaker 1: minutes in which the conditions are ripe for fusion for

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Speaker 1: those protons to bang together and make heavier stuff. And

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Speaker 1: so that's when helium was made. But you only had

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Speaker 1: like three minutes where the universe was in the right

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Speaker 1: conditions to make anything heavier, So you had huge amounts

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Speaker 1: of hydrogen, made a little bit of helium, but almost

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Speaker 1: nothing else. Basically, after the Big Bang, you had vast

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Speaker 1: quantities of hydrogen, trace amounts of helium, and almost nothing else. Basically,

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Speaker 1: no metal was around after the Big Bang.

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Speaker 2: Although I hear you saying almost, does that mean that

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Speaker 2: there was a little bit of the heavier metals in

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Speaker 2: the universe right after the Big Bang before stars got made.

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Speaker 1: It's impossible to say that there was none, But it's

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Speaker 1: very hard to make those heavier elements without the density

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Speaker 1: and the time. Using helium together makes something very unstable.

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Speaker 1: If you just start with two helium nuclei, you really

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Speaker 1: need three together to get the carbon, and that's much

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Speaker 1: harder to do without the density that you have in

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Speaker 1: stars and the time to fuse them. So it's possible

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Speaker 1: you made a little tiny bit of carbon after the

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Speaker 1: Big Bang, but it's overwhelmingly hydrogen, a little bit of helium,

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Speaker 1: and maybe tiny negligible amounts of carbon mm.

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Speaker 2: So the universe, I guess, was pretty pure hydrogen and helium,

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Speaker 2: and then those started to make stars, and that's when

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Speaker 2: the first metals really came into the universe exactly.

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Speaker 1: So those first stars were basically metal free, just huge

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Speaker 1: clouds of hydrogen with a little bit of helium in them,

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Speaker 1: and they produced the first metals. Right, they didn't start

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Speaker 1: with really any metal in them at all, but these

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Speaker 1: were huge stars. Turns out, if you form stars without

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Speaker 1: any metal in them, you get much bigger globs. And

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Speaker 1: those stars are really big, so they burn really hot

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Speaker 1: and they burn really fast, so they don't last for

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Speaker 1: very long. And then when they die, they spray their

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Speaker 1: metals out into the universe to see the next stars.

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Speaker 2: Right, and some of them burn and explode and collapse

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Speaker 2: without having used up all of the hydrogen and helium.

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Speaker 1: Right, Oh, yes, absolutely, stars do not burn all of

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Speaker 1: their hydrogen helium before they end their lives.

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Speaker 2: So like when those first stars exploded, how much of

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Speaker 2: them was still hydrogen and helium and how much of

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Speaker 2: the heavier metals had they made.

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Speaker 1: Yeah, that's a cool question. We can answer that by

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Speaker 1: looking at how much metal is in the next generation

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Speaker 1: of stars, because those little bits of metal are excellent

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Speaker 1: seeds for the next stars. Like, metal is heavier than

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Speaker 1: non metal, it has more protons, and it is more mass,

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Speaker 1: it's denser, so it's more likely to form a seed

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Speaker 1: of another star start that gravitational collapse. So the next

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Speaker 1: generation of stars. The stars were called population two. These

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Speaker 1: are still really really low metal. It's like less than

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Speaker 1: a tenth of one percent of those stars is metal,

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Speaker 1: so it's still overwhelmingly hydrogen and helium. Even in the

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Speaker 1: second generation of stars whoa.

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Speaker 2: So maybe painted pictures. So those first stars burned, they collapse,

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Speaker 2: They exploded, and then all that stuff recollapsed to get.

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Speaker 1: Yeah, exactly, but it didn't happen that quickly. Helium floats

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Speaker 1: around for like hundreds of millions of years before the

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Speaker 1: first stars are born. There's this period in the early

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Speaker 1: universe called the dark Ages, before there was any light

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Speaker 1: in the universe, just these dark clouds of hydrogen and helium.

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Speaker 1: And then those first stars burn for like just a

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Speaker 1: few million years. The larger the star is, the shorter

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Speaker 1: it's life. So those didn't burn for very long. But

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Speaker 1: then the next generation they're a little smaller and they

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Speaker 1: can burn for a very very long time.

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Speaker 2: Why were they smaller.

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Speaker 1: The more metal you have in the universe, the more

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Speaker 1: likely it is that a big cloud of gas is

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Speaker 1: going to break up and do multiple stars rather than

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Speaker 1: collapsing into one megastar, because you have all these different

402
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Speaker 1: places for it to seed. Remember, that for a star

403
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Speaker 1: to form, you need sort of special conditions. You need

404
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Speaker 1: a big cloud of gas, but you need to also

405
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Speaker 1: be cold enough so that it can collapse, and you

406
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Speaker 1: need some like gravitational seed to get that runaway effect going.

407
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Speaker 1: And so if you have a variety of different densities,

408
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Speaker 1: you're more likely to have smaller clumps than bigger clumps.

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Speaker 1: And those smaller stars tend to burn colder, and then

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Speaker 1: they last longer.

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Speaker 2: So if you have a giant cloud of hydrogen, it

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Speaker 2: doesn't break up as much. It just hangs around until

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Speaker 2: it all condenses into a giant star exactly.

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Speaker 1: And people might be imagining like that one cloud makes

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Speaker 1: one star, but it's more likely that a huge cloud

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Speaker 1: makes multiple stars all simultaneously. And if that cloud has

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Speaker 1: more metal in it, then you have more seeds for

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Speaker 1: those stars, so you end up with more smaller stars

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Speaker 1: rather than fewer megastars like you did in the first batch.

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Speaker 2: Okay, so then that's the second generation of stars, right.

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Speaker 1: Yeah, exactly, And those stars were formed like thirteen fourteen

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Speaker 1: billion years ago, but they burn a long time because

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Speaker 1: they're small, they're redder, they're colder stars. So we can

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Speaker 1: still see some of those stars around in the universe,

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Speaker 1: especially in globular clusters.

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Speaker 2: Like around us or only far away or further back

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Speaker 2: in time.

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Speaker 1: They're also in like the heart of our galaxy. So

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Speaker 1: population two stars are all around.

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Speaker 2: Did that generation of stars then they eventually explode and

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Speaker 2: make the next generation of stars?

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Speaker 1: That definitely happened. It's a little bit misleading to think

433
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Speaker 1: about these as generations in a sort of crisp sense.

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Speaker 1: It's not like all that first generation died and then

435
00:20:14,359 --> 00:20:17,360
Speaker 1: there's only the second generation and there's only the third generation.

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Speaker 1: Every star is formed from remnants of multiple stars, and

437
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Speaker 1: some of them might have gone through one, two, three,

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Speaker 1: four generations, maybe even more. It depends on the size

439
00:20:26,240 --> 00:20:29,400
Speaker 1: of those stars. So this categorization is very rough. It's

440
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Speaker 1: not super precise. It's not like all the stars are

441
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Speaker 1: in sync. But the latest generation of stars, which are

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Speaker 1: called population one stars for more recently in the universe,

443
00:20:39,119 --> 00:20:41,920
Speaker 1: when there's been more time to make metal in the universe.

444
00:20:42,320 --> 00:20:45,520
Speaker 1: So these we call high metallicity stars, which means they

445
00:20:45,560 --> 00:20:48,240
Speaker 1: have like between one and four percent metal.

446
00:20:48,480 --> 00:20:50,880
Speaker 2: Wait wait, wait, the third generation of stars is called

447
00:20:50,920 --> 00:20:51,920
Speaker 2: population one.

448
00:20:52,480 --> 00:20:55,320
Speaker 1: Yeah, that's exactly right. Population one are the ones made

449
00:20:55,320 --> 00:20:59,600
Speaker 1: most recently. Population two is the previous generation. Population three

450
00:21:00,160 --> 00:21:04,399
Speaker 1: is still somewhat theoretical first generation of stars. And I

451
00:21:04,520 --> 00:21:06,640
Speaker 1: know the naming system is ridiculous, and I won't defend

452
00:21:06,680 --> 00:21:07,600
Speaker 1: it even for a moment.

453
00:21:07,760 --> 00:21:09,240
Speaker 2: What generation is our sun?

454
00:21:09,400 --> 00:21:11,919
Speaker 1: Our son we think is a population one star, so

455
00:21:11,920 --> 00:21:13,640
Speaker 1: it's part of the most recent generation.

456
00:21:13,880 --> 00:21:15,760
Speaker 2: All right, Well, then let's get to the question of

457
00:21:15,840 --> 00:21:19,119
Speaker 2: how much metal is in our star, the Sun, and

458
00:21:19,160 --> 00:21:22,240
Speaker 2: whether it rocks or not. So let's dig into that.

459
00:21:22,400 --> 00:21:37,200
Speaker 2: But first let's take a quick break. All right, we're

460
00:21:37,200 --> 00:21:40,480
Speaker 2: asking the question how much metal is in the Sun,

461
00:21:41,200 --> 00:21:44,280
Speaker 2: and by metal we mean elements that are not hydrogen

462
00:21:44,359 --> 00:21:44,800
Speaker 2: or helium.

463
00:21:44,880 --> 00:21:49,679
Speaker 1: Yeah, exactly. We want to know how much oxygen, carbon, neon, nitrogen, sulfur, iron,

464
00:21:49,760 --> 00:21:52,520
Speaker 1: all that stuff all added up. That's even like the

465
00:21:52,560 --> 00:21:54,679
Speaker 1: first most basic question you want to know, like how

466
00:21:54,760 --> 00:21:56,800
Speaker 1: much of that heavier stuff is in the Sun. And

467
00:21:56,840 --> 00:21:59,080
Speaker 1: then of course we want to know the proportions also,

468
00:21:59,160 --> 00:22:01,480
Speaker 1: But we first need to nail down the initial question.

469
00:22:01,920 --> 00:22:05,120
Speaker 2: Well, why do you think astronomers call everything not hygrogen

470
00:22:05,200 --> 00:22:08,440
Speaker 2: and helium metals because they couldn't come up with another name?

471
00:22:08,840 --> 00:22:12,160
Speaker 2: Or is there rationale there? Like I would think metals

472
00:22:12,560 --> 00:22:15,960
Speaker 2: maybe in chemistry has the connotation that it conducts electricity

473
00:22:16,160 --> 00:22:20,320
Speaker 2: or is shining. So what's the astronomer's excuse.

474
00:22:20,560 --> 00:22:23,520
Speaker 1: Well, I think there is this division between hydrogen helium,

475
00:22:23,720 --> 00:22:27,119
Speaker 1: of which there's so much in the universe, and everything else,

476
00:22:27,680 --> 00:22:30,000
Speaker 1: and so you really need another category. I don't know

477
00:22:30,040 --> 00:22:32,439
Speaker 1: if metal was the right way to describe it, but

478
00:22:32,560 --> 00:22:35,240
Speaker 1: there definitely are two different categories. There really is hydrogen

479
00:22:35,280 --> 00:22:37,320
Speaker 1: helium and all the other stuff in the universe.

480
00:22:37,400 --> 00:22:40,600
Speaker 2: M So it's more of a name just given by

481
00:22:40,640 --> 00:22:42,120
Speaker 2: population or abundancy.

482
00:22:43,200 --> 00:22:45,840
Speaker 1: Also, this is the stuff produced by stars, so it's

483
00:22:45,840 --> 00:22:48,480
Speaker 1: sort of like the output of stars. It doesn't have

484
00:22:48,520 --> 00:22:50,680
Speaker 1: to do as much with like the chemical properties or

485
00:22:50,720 --> 00:22:53,280
Speaker 1: the behaviors or the appearance the way it does in chemistry.

486
00:22:53,760 --> 00:22:56,040
Speaker 1: It's more about the abundance in the universe and how

487
00:22:56,040 --> 00:22:56,560
Speaker 1: it was made.

488
00:22:56,800 --> 00:22:59,639
Speaker 2: All right, So then the latest generation of star has

489
00:22:59,720 --> 00:23:03,720
Speaker 2: a one point four to four percent metals.

490
00:23:03,520 --> 00:23:06,680
Speaker 1: Yeah, exactly, And so there's a variation there, like depending

491
00:23:06,720 --> 00:23:08,920
Speaker 1: on where you were when you were formed, and also

492
00:23:08,920 --> 00:23:12,359
Speaker 1: whether you can make metals inside you. There's a pretty

493
00:23:12,359 --> 00:23:14,639
Speaker 1: big spread and how much metal there is in stars.

494
00:23:15,000 --> 00:23:18,520
Speaker 1: On the other hand, most stars still hydrogen helium. Like,

495
00:23:18,560 --> 00:23:22,760
Speaker 1: we've been burning hydrogen for fourteen billion years. We've hardly

496
00:23:22,760 --> 00:23:25,480
Speaker 1: made a dent in the fraction of the universe that

497
00:23:25,720 --> 00:23:27,119
Speaker 1: is hydrogen.

498
00:23:26,880 --> 00:23:29,880
Speaker 2: You mean our star or in the universe in general.

499
00:23:29,920 --> 00:23:32,560
Speaker 1: The universe in general, you know, the universe is still

500
00:23:33,000 --> 00:23:36,200
Speaker 1: mostly hydrogen. Like ninety two percent of the universe right

501
00:23:36,200 --> 00:23:37,720
Speaker 1: now is hydrogen.

502
00:23:37,880 --> 00:23:40,560
Speaker 2: So like our star right now is burning hydrogen. Were

503
00:23:40,600 --> 00:23:43,080
Speaker 2: you saying, like the amount of hydrogen it's burning or

504
00:23:43,359 --> 00:23:46,280
Speaker 2: fusing together is super tiny tiny.

505
00:23:46,280 --> 00:23:48,600
Speaker 1: I'm saying, we've been burning it for fourteen billion years

506
00:23:48,600 --> 00:23:50,840
Speaker 1: and we've hardly made a dent. Yeah, stars are the

507
00:23:50,920 --> 00:23:55,359
Speaker 1: universe's mechanism for like turning light stuff like hydrogen into

508
00:23:55,400 --> 00:23:57,320
Speaker 1: heavier stuff. And you might think, wow, we've been burning

509
00:23:57,320 --> 00:23:59,160
Speaker 1: for a long time. We must have plowed through it all.

510
00:23:59,200 --> 00:24:02,560
Speaker 1: But there's still vast, vast quantities of hydrogen out there.

511
00:24:02,640 --> 00:24:06,480
Speaker 2: Now, Why is that just because there's so much hydrogen

512
00:24:06,520 --> 00:24:08,440
Speaker 2: and helium in the sun. But really the part that

513
00:24:08,520 --> 00:24:11,520
Speaker 2: is fusing, it's only at the very tiny center of it.

514
00:24:11,680 --> 00:24:13,960
Speaker 2: Or why isn't it burning up faster?

515
00:24:14,280 --> 00:24:16,560
Speaker 1: The reason you suggest it is totally accurate. Like fusion

516
00:24:16,600 --> 00:24:19,199
Speaker 1: happens mostly at the core where things are dense and

517
00:24:19,240 --> 00:24:22,000
Speaker 1: things are hot, at least in the initial stages. Then

518
00:24:22,040 --> 00:24:24,280
Speaker 1: when the core of the sun fills with ash or

519
00:24:24,320 --> 00:24:27,480
Speaker 1: fills with heavier metals than the sun confuse, then the

520
00:24:27,520 --> 00:24:31,960
Speaker 1: fusion moves outwards. But also remember fusion is hard. Even

521
00:24:32,000 --> 00:24:34,440
Speaker 1: if you have an enormous pile of hydrogen you squeeze

522
00:24:34,440 --> 00:24:37,400
Speaker 1: it to the right pressure and density and temperature, it's

523
00:24:37,400 --> 00:24:39,560
Speaker 1: not like all the hydrogen is instantly just going to

524
00:24:39,600 --> 00:24:42,040
Speaker 1: fuse into helium. You need a lot of hydrogen and

525
00:24:42,080 --> 00:24:44,919
Speaker 1: a lot of time to get any fusion happening. So

526
00:24:44,960 --> 00:24:47,280
Speaker 1: it's a very low probability thing, which is why you

527
00:24:47,320 --> 00:24:51,160
Speaker 1: need an enormous pile a very high temperature, high density

528
00:24:51,160 --> 00:24:52,720
Speaker 1: gas to get any of it to happen.

529
00:24:53,000 --> 00:24:55,800
Speaker 2: All right, So then that's kind of the general picture.

530
00:24:55,840 --> 00:24:57,840
Speaker 2: But what about our sun? How much of our sun

531
00:24:57,960 --> 00:25:00,520
Speaker 2: is still hydrogen and helium and how much it is

532
00:25:00,920 --> 00:25:01,879
Speaker 2: badly named metals.

533
00:25:03,960 --> 00:25:06,560
Speaker 1: So about twenty years ago we thought we had this settled.

534
00:25:07,040 --> 00:25:09,080
Speaker 1: We had studied the sun and looked at the light

535
00:25:09,080 --> 00:25:10,840
Speaker 1: that comes from the sun, the spectrum of it, like

536
00:25:10,880 --> 00:25:12,920
Speaker 1: how much red light is there, how much green light,

537
00:25:12,920 --> 00:25:15,159
Speaker 1: how much blue light, and use that to try to

538
00:25:15,200 --> 00:25:17,040
Speaker 1: figure out what was in the sun, and we thought

539
00:25:17,040 --> 00:25:18,960
Speaker 1: we had it nailed down. We thought the answer was

540
00:25:19,000 --> 00:25:22,480
Speaker 1: about one point eight percent metal.

541
00:25:22,480 --> 00:25:24,480
Speaker 2: Meaning like if you look at the light from the Sun,

542
00:25:25,200 --> 00:25:27,439
Speaker 2: the spectrum of the light from the Sun sort of

543
00:25:27,480 --> 00:25:29,159
Speaker 2: can tell you what the Sun is made out of,

544
00:25:29,320 --> 00:25:30,120
Speaker 2: or we thought it could.

545
00:25:30,320 --> 00:25:33,320
Speaker 1: Yeah, exactly. The Sun is really fascinating because, on one hand,

546
00:25:33,440 --> 00:25:35,600
Speaker 1: a lot of the light comes from just the Sun

547
00:25:35,640 --> 00:25:38,440
Speaker 1: being hot. Everything out there in the universe that's made

548
00:25:38,480 --> 00:25:41,480
Speaker 1: of charged particles will glow based on its temperature, and

549
00:25:41,480 --> 00:25:44,159
Speaker 1: the hotter things are, the higher energy the photons it

550
00:25:44,200 --> 00:25:46,600
Speaker 1: will be released. So a lot of the light from

551
00:25:46,640 --> 00:25:48,880
Speaker 1: the Sun is what we call just black body radiation,

552
00:25:49,240 --> 00:25:51,880
Speaker 1: something hot giving off light the way like I give

553
00:25:51,880 --> 00:25:53,920
Speaker 1: off light and you give off light. We don't give

554
00:25:53,920 --> 00:25:56,080
Speaker 1: off light in the visible spectrum the way the Sun

555
00:25:56,119 --> 00:25:58,720
Speaker 1: does because we're not white hot the way the Sun is.

556
00:25:59,040 --> 00:26:00,600
Speaker 1: But that's where a lot of the light from the

557
00:26:00,600 --> 00:26:01,439
Speaker 1: Sun comes from.

558
00:26:01,680 --> 00:26:03,120
Speaker 2: Where does the other light come from.

559
00:26:03,200 --> 00:26:05,639
Speaker 1: The other light comes from specific atoms in the Sun

560
00:26:05,960 --> 00:26:09,159
Speaker 1: emitting light or absorbing that light. So I feel like

561
00:26:09,160 --> 00:26:11,560
Speaker 1: an oxygen atom in the atmosphere of the Sun and

562
00:26:11,640 --> 00:26:14,119
Speaker 1: it gets hot, its electrons jump up a couple of

563
00:26:14,240 --> 00:26:16,920
Speaker 1: energy levels, then they jump down, they relax, and they

564
00:26:16,920 --> 00:26:20,840
Speaker 1: emit a photon, and that photon it's very specific energy.

565
00:26:20,840 --> 00:26:24,399
Speaker 1: It corresponds to the difference in the energy levels of

566
00:26:24,400 --> 00:26:27,679
Speaker 1: that electron around the oxygen atom. Every atom out there

567
00:26:27,760 --> 00:26:31,480
Speaker 1: can emit an absorbed light in very specific wavelengths. So

568
00:26:31,520 --> 00:26:33,160
Speaker 1: if you look at the spectrum from the Sun, there's

569
00:26:33,200 --> 00:26:37,560
Speaker 1: this overall black body radiation, then these spikes where certain

570
00:26:37,600 --> 00:26:41,119
Speaker 1: atoms are emitting light that correspond to their energy levels

571
00:26:41,359 --> 00:26:44,760
Speaker 1: and their dips where other atoms are absorbing light that's

572
00:26:44,800 --> 00:26:47,080
Speaker 1: produced by the Sun at the energy levels that they

573
00:26:47,080 --> 00:26:49,280
Speaker 1: can do it. So you look at all those wiggles

574
00:26:49,280 --> 00:26:52,360
Speaker 1: in the spectrum and you can tell what's in the sun, or.

575
00:26:52,280 --> 00:26:54,879
Speaker 2: At least it seems like we thought we could. So

576
00:26:54,920 --> 00:26:56,720
Speaker 2: we did that for our sun, and we thought it

577
00:26:56,800 --> 00:26:58,840
Speaker 2: had a certain amount of metals in it. But then

578
00:26:58,880 --> 00:26:59,440
Speaker 2: what happened.

579
00:27:00,000 --> 00:27:02,040
Speaker 1: I thought, Okay, that's cool, one point eight percent. That

580
00:27:02,080 --> 00:27:04,720
Speaker 1: makes total sense. But then people thought, well, let's cross

581
00:27:04,760 --> 00:27:07,159
Speaker 1: check it. Let's see if we can measure what's in

582
00:27:07,160 --> 00:27:09,879
Speaker 1: the sun using another technique and come up with the

583
00:27:09,920 --> 00:27:12,240
Speaker 1: same answer. Another way to figure out what's in the

584
00:27:12,280 --> 00:27:15,320
Speaker 1: sun is to watch it boil is to like look

585
00:27:15,359 --> 00:27:18,439
Speaker 1: for waves in the surface of the Sun because that

586
00:27:18,440 --> 00:27:21,760
Speaker 1: tells you like how thick the sun is, the viscosity

587
00:27:21,800 --> 00:27:24,480
Speaker 1: of the Sun, which depends on what's in there, what's

588
00:27:24,480 --> 00:27:25,760
Speaker 1: sort of mucking around?

589
00:27:26,080 --> 00:27:27,919
Speaker 2: Wait, what what do you mean? Like as you look

590
00:27:27,960 --> 00:27:30,000
Speaker 2: at the surface of the Sun, you see it churning.

591
00:27:30,240 --> 00:27:33,399
Speaker 2: It's like super hot plasma, right mm hmm. And the

592
00:27:33,440 --> 00:27:37,719
Speaker 2: way the plasma churns tells you how goopy it is.

593
00:27:37,960 --> 00:27:41,280
Speaker 1: Yeah. They call it helio seismology, and it's sort of

594
00:27:41,280 --> 00:27:44,160
Speaker 1: similar to the way you can use earthquakes to understand

595
00:27:44,280 --> 00:27:46,920
Speaker 1: what the Earth is made out of. Like an earthquake

596
00:27:47,040 --> 00:27:49,879
Speaker 1: shakes the Earth, and then that shaking travels through the

597
00:27:49,920 --> 00:27:53,159
Speaker 1: Earth and it reflects at boundaries. Like that's how we

598
00:27:53,280 --> 00:27:56,280
Speaker 1: know where that boundary is between various layers of the Earth,

599
00:27:56,359 --> 00:27:58,600
Speaker 1: And we can also deduce things about like what's there

600
00:27:58,720 --> 00:28:01,840
Speaker 1: because how it bounces and reflects depends on the relative

601
00:28:01,880 --> 00:28:05,159
Speaker 1: density of things at those layers. So just by measuring

602
00:28:05,200 --> 00:28:07,640
Speaker 1: earthquakes at the surface, you can get a pretty good

603
00:28:07,640 --> 00:28:10,600
Speaker 1: picture for what's in the Earth. In the same way

604
00:28:10,680 --> 00:28:13,359
Speaker 1: we can look at ripples on the surface of the sun.

605
00:28:13,880 --> 00:28:17,280
Speaker 1: Helio seismology, they call it, to get a picture for

606
00:28:17,359 --> 00:28:18,480
Speaker 1: what's in the sun.

607
00:28:18,880 --> 00:28:21,760
Speaker 2: We don't have earthquake measuring devices on the sun. How

608
00:28:21,840 --> 00:28:24,840
Speaker 2: do we know the shaking of the surface of the sun.

609
00:28:25,320 --> 00:28:27,159
Speaker 1: So we don't need a complete picture of what's in

610
00:28:27,200 --> 00:28:29,720
Speaker 1: the sun. But we can watch waves move across the

611
00:28:29,760 --> 00:28:31,000
Speaker 1: surface of the sun. You know, we have a lot

612
00:28:31,000 --> 00:28:33,600
Speaker 1: of telescopes that can look at the Sun and they

613
00:28:33,600 --> 00:28:36,000
Speaker 1: can see the behavior and the churning on the surface,

614
00:28:36,440 --> 00:28:38,479
Speaker 1: and there's a lot of stuff going on there. But

615
00:28:38,520 --> 00:28:40,440
Speaker 1: we only need a sort of rough picture of what's

616
00:28:40,440 --> 00:28:42,920
Speaker 1: in the sun because it turns out this one very

617
00:28:42,960 --> 00:28:46,120
Speaker 1: particular thing that's controlled by the metals that we're trying

618
00:28:46,120 --> 00:28:48,320
Speaker 1: to get a sense of. It's a balance between two

619
00:28:48,440 --> 00:28:51,240
Speaker 1: processes that are trying to move the heat out of

620
00:28:51,280 --> 00:28:53,720
Speaker 1: the sun. The sun has sort of two parts to it.

621
00:28:53,720 --> 00:28:56,440
Speaker 1: It's like the outermost part and the innermost part. And

622
00:28:56,520 --> 00:28:58,959
Speaker 1: the innermost part a lot of heat is being created

623
00:28:58,960 --> 00:29:02,160
Speaker 1: it's radiating out, so that radiation comes out from the

624
00:29:02,160 --> 00:29:05,040
Speaker 1: core and hits the outer part of the sun. But

625
00:29:05,160 --> 00:29:07,240
Speaker 1: that outer part can be kind of opaque because of

626
00:29:07,320 --> 00:29:11,320
Speaker 1: like oxygen or heavy elements can absorb those photons. So

627
00:29:11,360 --> 00:29:14,560
Speaker 1: that means that that energy can't be radiated out from

628
00:29:14,600 --> 00:29:16,800
Speaker 1: the core of the Sun. Instead, you need to get

629
00:29:16,800 --> 00:29:20,520
Speaker 1: that energy out using another method we call convection, basically

630
00:29:20,600 --> 00:29:23,240
Speaker 1: just like hot stuff rising up the way it does

631
00:29:23,280 --> 00:29:25,480
Speaker 1: in a pot of water. So there's sort of two

632
00:29:25,560 --> 00:29:28,080
Speaker 1: parts of the Sun, one where photons can bring the

633
00:29:28,160 --> 00:29:30,200
Speaker 1: energy out and the other where we have to rely

634
00:29:30,360 --> 00:29:33,480
Speaker 1: on convection. And there's a boundary between these two regions,

635
00:29:33,720 --> 00:29:36,200
Speaker 1: and that depends a lot on like how much oxygen

636
00:29:36,360 --> 00:29:38,280
Speaker 1: is there in the Sun, and that's what we're trying

637
00:29:38,280 --> 00:29:41,280
Speaker 1: to measure with this helio seismology. We're trying to figure out,

638
00:29:41,280 --> 00:29:44,200
Speaker 1: like where's the threshold between these two parts of the

639
00:29:44,240 --> 00:29:45,200
Speaker 1: inside of the sun.

640
00:29:45,400 --> 00:29:48,240
Speaker 2: And we do this by just looking at the flow

641
00:29:48,840 --> 00:29:51,040
Speaker 2: that you can see in the picture of the sun.

642
00:29:51,160 --> 00:29:53,400
Speaker 2: Or do we have like an X ray way to

643
00:29:53,440 --> 00:29:54,360
Speaker 2: look inside the sun.

644
00:29:54,520 --> 00:29:56,920
Speaker 1: No, we have no X ray. Unfortunately, it's just effectively

645
00:29:57,040 --> 00:30:00,520
Speaker 1: sound waves in the sun. And of course nobody's hearing

646
00:30:00,560 --> 00:30:02,760
Speaker 1: these things. When we say sound waves, we just mean

647
00:30:02,760 --> 00:30:05,360
Speaker 1: pressure waves moving through the Sun, but just the same

648
00:30:05,400 --> 00:30:08,480
Speaker 1: way that earthquakes make effectively sound waves through the Earth,

649
00:30:08,720 --> 00:30:11,320
Speaker 1: and you can listen to the earth ringing just by

650
00:30:11,320 --> 00:30:13,960
Speaker 1: seeing the Earth shake. If we watch the surface of

651
00:30:14,000 --> 00:30:16,600
Speaker 1: the Sun, we don't have like instruments on the surface

652
00:30:16,640 --> 00:30:19,280
Speaker 1: that measure the actual shaking, but you can see these

653
00:30:19,400 --> 00:30:22,720
Speaker 1: ripples in the plasma on the surface. You can effectively

654
00:30:22,800 --> 00:30:26,480
Speaker 1: see sound moving through the Sun and bouncing back. And

655
00:30:26,560 --> 00:30:29,160
Speaker 1: this boundary between the two parts of the Sun, one

656
00:30:29,160 --> 00:30:31,920
Speaker 1: that's opaque to photons and one that isn't shows up

657
00:30:31,960 --> 00:30:34,360
Speaker 1: as like a glitch in the sound waves. It changes

658
00:30:34,400 --> 00:30:36,560
Speaker 1: how those sound waves move through the Sun.

659
00:30:37,240 --> 00:30:39,480
Speaker 2: Well, wait, are you saying there's sort of like two

660
00:30:39,720 --> 00:30:41,760
Speaker 2: kinds of sun surfaces.

661
00:30:42,000 --> 00:30:44,200
Speaker 1: Yeah, there's like a surface within the surface, the same

662
00:30:44,240 --> 00:30:46,840
Speaker 1: way that like the Earth has multiple layers to it.

663
00:30:46,880 --> 00:30:48,720
Speaker 1: You know, it's the mantle and the outer core and

664
00:30:48,760 --> 00:30:51,520
Speaker 1: the inner core, et cetera. The Sun also has these

665
00:30:51,560 --> 00:30:55,200
Speaker 1: regions and there's this boundary. They think it's like seventy

666
00:30:55,320 --> 00:30:58,720
Speaker 1: ish percent of the solar radius. Within that photons can

667
00:30:58,800 --> 00:31:01,920
Speaker 1: like fly free, and you this radiative transfer where photons

668
00:31:01,920 --> 00:31:05,040
Speaker 1: can move heat out from the center. The outer part

669
00:31:05,080 --> 00:31:08,040
Speaker 1: is more opake and photons can't really get through it.

670
00:31:08,040 --> 00:31:09,880
Speaker 1: It's the only way to get heat out from the Sun.

671
00:31:09,920 --> 00:31:13,520
Speaker 1: There is more like convection like hot gas rising up.

672
00:31:13,760 --> 00:31:15,600
Speaker 2: But then what are you basically saying that looking at

673
00:31:15,600 --> 00:31:18,200
Speaker 2: these sound waves tells us a different number for what

674
00:31:18,280 --> 00:31:19,200
Speaker 2: the Sun is made out of.

675
00:31:19,440 --> 00:31:22,080
Speaker 1: Exactly, looking at the sound waves tells us something about

676
00:31:22,120 --> 00:31:24,600
Speaker 1: where this balance is between the two different parts of

677
00:31:24,600 --> 00:31:27,320
Speaker 1: the Sun, and that depends on how much metal is

678
00:31:27,360 --> 00:31:30,360
Speaker 1: in the Sun, because the metallicity of the Sun controls

679
00:31:30,400 --> 00:31:34,440
Speaker 1: whether it's opaque or transparent. You have more oxygen, more carbon,

680
00:31:34,520 --> 00:31:38,440
Speaker 1: more neon. That makes the Sun more opaque, which changes

681
00:31:38,480 --> 00:31:41,040
Speaker 1: how far the photons can get. So if we can

682
00:31:41,160 --> 00:31:43,600
Speaker 1: use sound waves on the surface of the Sun figure

683
00:31:43,600 --> 00:31:47,160
Speaker 1: out where is this transition within the Sun between opaque

684
00:31:47,280 --> 00:31:50,160
Speaker 1: and transparent to these photons, then we could figure out

685
00:31:50,400 --> 00:31:53,040
Speaker 1: how much metal is in the Sun because the metallicity

686
00:31:53,120 --> 00:31:55,360
Speaker 1: controls where that transition is.

687
00:31:55,640 --> 00:31:57,720
Speaker 2: But then why do metals make the Sun more opake?

688
00:31:58,040 --> 00:32:00,560
Speaker 1: These heavy elements like oxygen, they like to absorb these

689
00:32:00,560 --> 00:32:04,280
Speaker 1: photons like more than hydrogen, Yeah, more than hydrogen. You know,

690
00:32:04,320 --> 00:32:06,959
Speaker 1: every atom likes to absorb photons of a certain energy,

691
00:32:07,240 --> 00:32:09,080
Speaker 1: and so the kinds of energy that tend to be

692
00:32:09,080 --> 00:32:11,719
Speaker 1: produced in fusion tend to also be the kind that

693
00:32:11,800 --> 00:32:15,000
Speaker 1: oxygen likes to gobble up. For example. So if you

694
00:32:15,000 --> 00:32:17,600
Speaker 1: do all these calculations, you figure out, well, where is

695
00:32:17,680 --> 00:32:20,400
Speaker 1: this threshold where's the sun become opaque inside of it?

696
00:32:20,720 --> 00:32:22,880
Speaker 1: And what does that mean about the amount of metal

697
00:32:22,920 --> 00:32:26,000
Speaker 1: inside the sun? You get a different number. So from

698
00:32:26,080 --> 00:32:28,760
Speaker 1: helio seismology, from these sound waves, we get the number

699
00:32:28,760 --> 00:32:31,600
Speaker 1: one point eight percent. Whereas we look at the spectrum

700
00:32:31,640 --> 00:32:33,520
Speaker 1: of light from the sun, we got the number one

701
00:32:33,520 --> 00:32:36,520
Speaker 1: point three percent. So we thought, oh, this would be

702
00:32:36,520 --> 00:32:38,440
Speaker 1: a great way to cross check and to just make

703
00:32:38,480 --> 00:32:40,280
Speaker 1: sure we understand what's in the sun. And then it

704
00:32:40,320 --> 00:32:42,800
Speaker 1: turns out, oops, the numbers don't agree.

705
00:32:43,040 --> 00:32:45,920
Speaker 2: Now is that do you think maybe because looking at

706
00:32:45,960 --> 00:32:47,760
Speaker 2: the spectrum of the sun only kind of maybe tells

707
00:32:47,800 --> 00:32:49,280
Speaker 2: you what's in the surface of the sun.

708
00:32:49,560 --> 00:32:51,400
Speaker 1: It is possible, but they've accounted for that. They have

709
00:32:51,480 --> 00:32:54,280
Speaker 1: models for where these things are distributed in the sun

710
00:32:54,320 --> 00:32:57,200
Speaker 1: and how much they would radiate. So there are definitely

711
00:32:57,280 --> 00:32:59,760
Speaker 1: questions there and things people are trying to drill down on,

712
00:33:00,080 --> 00:33:01,680
Speaker 1: but they do think they've accounted for that.

713
00:33:02,600 --> 00:33:04,360
Speaker 2: But the second one of the ways seems a little

714
00:33:04,400 --> 00:33:08,840
Speaker 2: a bit more circumspect, I guess, or more indirect than

715
00:33:08,960 --> 00:33:10,760
Speaker 2: actually just looking at the light from the sun.

716
00:33:11,760 --> 00:33:14,120
Speaker 1: It does in the end, we're always just getting information

717
00:33:14,200 --> 00:33:16,240
Speaker 1: from far away and using that to try to infer

718
00:33:16,320 --> 00:33:18,800
Speaker 1: what's going on, and what's happening here is something I

719
00:33:18,880 --> 00:33:20,959
Speaker 1: love in science. It's like, well, let's cross check our

720
00:33:21,040 --> 00:33:23,880
Speaker 1: understanding by seeing if we could do this two different ways,

721
00:33:24,160 --> 00:33:26,920
Speaker 1: making different assumptions, or probing our model in different ways

722
00:33:26,960 --> 00:33:30,040
Speaker 1: to see whether it breaks. And this kind of detailed

723
00:33:30,080 --> 00:33:32,600
Speaker 1: work has led to crazy discoveries in the past. You know,

724
00:33:32,920 --> 00:33:35,800
Speaker 1: when we, for example, predicted how many neutrinos would be

725
00:33:35,800 --> 00:33:37,880
Speaker 1: coming from the sun versus how many new trinos we

726
00:33:37,920 --> 00:33:40,000
Speaker 1: saw from the sun, and we saw a huge difference.

727
00:33:40,400 --> 00:33:44,400
Speaker 1: That led to understanding neutrino oscillations and neutrino masses. So

728
00:33:44,600 --> 00:33:46,600
Speaker 1: not every way is going to be as precise, but

729
00:33:46,640 --> 00:33:48,560
Speaker 1: it's important to have different ways to cross check each

730
00:33:48,560 --> 00:33:50,600
Speaker 1: other and to try to get some hints about what's

731
00:33:50,640 --> 00:33:52,120
Speaker 1: really going on inside the sun.

732
00:33:52,680 --> 00:33:55,120
Speaker 2: Well, it sounds like we've measured how much metal is

733
00:33:55,120 --> 00:33:57,400
Speaker 2: in the sun in two different ways and they disagree

734
00:33:57,880 --> 00:34:00,920
Speaker 2: by a pretty big amount, and so let's get into

735
00:34:00,960 --> 00:34:04,160
Speaker 2: what the difference means, who's right, who's wrong, and how

736
00:34:04,200 --> 00:34:06,760
Speaker 2: metal is the sun. So let's dig into that. But

737
00:34:06,800 --> 00:34:21,840
Speaker 2: first let's take another quick break. All right, we're asking

738
00:34:21,880 --> 00:34:24,040
Speaker 2: how much metal is in the sun, and it sounds

739
00:34:24,040 --> 00:34:27,200
Speaker 2: like we have two answers. One way, by looking at

740
00:34:27,200 --> 00:34:29,879
Speaker 2: the light from the sun tells us that it's one

741
00:34:29,880 --> 00:34:33,560
Speaker 2: point three percent non hydrogen and helium. But looking at

742
00:34:33,600 --> 00:34:37,560
Speaker 2: the flow of the plasma and how the sound ways

743
00:34:37,600 --> 00:34:39,920
Speaker 2: travel across the surface of the Sun, that tells us

744
00:34:39,920 --> 00:34:42,920
Speaker 2: that maybe the sun is one point eight percent non

745
00:34:43,239 --> 00:34:46,439
Speaker 2: hydrogen and helium. So who's right and who's wrong.

746
00:34:47,520 --> 00:34:50,560
Speaker 1: We don't know yet, But we have a third answer.

747
00:34:51,000 --> 00:34:53,440
Speaker 1: People came up with yet another way to try to

748
00:34:53,440 --> 00:34:54,600
Speaker 1: figure out how much.

749
00:34:54,480 --> 00:34:56,839
Speaker 2: Metal is in the sun, just asking the sun.

750
00:34:58,160 --> 00:35:00,560
Speaker 1: Nobody thought of that. Oh my god, you know, if

751
00:35:00,600 --> 00:35:02,359
Speaker 1: the Sun really isn't a rock band, it's gonna love

752
00:35:02,400 --> 00:35:06,480
Speaker 1: doing interviews. But this third way actually does use neutrinos,

753
00:35:06,880 --> 00:35:09,520
Speaker 1: because fusion at the heart of the Sun produces vast,

754
00:35:09,600 --> 00:35:13,960
Speaker 1: vast quantities of neutrinos, these tiny, little ghostly particles that

755
00:35:14,000 --> 00:35:16,560
Speaker 1: are everwhere, but we can't feel them because they only

756
00:35:16,600 --> 00:35:19,480
Speaker 1: have weak interactions. They have no electric charge, they have

757
00:35:19,520 --> 00:35:23,120
Speaker 1: no strong force charge. They're very difficult to spot. But

758
00:35:23,160 --> 00:35:26,399
Speaker 1: we have technologies neutrino eyeballs, we've invented to be able

759
00:35:26,400 --> 00:35:28,759
Speaker 1: to pick out a few of these neutrinos. We can

760
00:35:28,880 --> 00:35:32,960
Speaker 1: also measure the energy of those neutrinos. And the neutrinos

761
00:35:32,960 --> 00:35:36,080
Speaker 1: are produced by fusion in the sun, and how much

762
00:35:36,160 --> 00:35:38,600
Speaker 1: metal you have in the sun affects the rate at

763
00:35:38,640 --> 00:35:41,759
Speaker 1: which that fusion happens and also affects the energy of

764
00:35:41,800 --> 00:35:45,719
Speaker 1: the neutrinos that's produced. We're trying to fuse protons and

765
00:35:45,760 --> 00:35:48,320
Speaker 1: protons together. If there's a bunch of heavy metal around

766
00:35:48,320 --> 00:35:51,640
Speaker 1: that actually interferes with the fusion, makes it less likely,

767
00:35:51,680 --> 00:35:54,080
Speaker 1: it makes it more important to have higher energy on

768
00:35:54,120 --> 00:35:58,280
Speaker 1: those protons, etc. So the neutrino energy spectrum you expect

769
00:35:58,480 --> 00:36:01,200
Speaker 1: depends on how much metal in the sun, but it's

770
00:36:01,239 --> 00:36:03,200
Speaker 1: a bit of a weak effect. It's not a very

771
00:36:03,239 --> 00:36:05,360
Speaker 1: strong way to measure this quantity.

772
00:36:05,560 --> 00:36:07,600
Speaker 2: Well, also, what do you compare it to, like, how

773
00:36:07,640 --> 00:36:10,239
Speaker 2: do you know what the right amount of neutrinos should

774
00:36:10,280 --> 00:36:11,960
Speaker 2: be for a certain amount of metals.

775
00:36:12,320 --> 00:36:15,480
Speaker 1: Yeah, great question. We have a really detailed model of

776
00:36:15,520 --> 00:36:18,680
Speaker 1: the fusion and how it produces neutrinos, and that's been

777
00:36:18,680 --> 00:36:21,359
Speaker 1: the subject of decades of study, and of course, first

778
00:36:21,400 --> 00:36:24,280
Speaker 1: there were big mysteries we predicted a huge amount of neutrinos,

779
00:36:24,280 --> 00:36:26,480
Speaker 1: we only saw a third of them. Later we discovered

780
00:36:26,520 --> 00:36:29,279
Speaker 1: that's because those neutrinos are changing into another kind of

781
00:36:29,360 --> 00:36:32,480
Speaker 1: neutrino as they travel through space. Check out our episode

782
00:36:32,480 --> 00:36:35,000
Speaker 1: on neutrino oscillation if you want to understand that more.

783
00:36:35,440 --> 00:36:37,800
Speaker 1: But yeah, there are definitely uncertainties there. These are models

784
00:36:37,840 --> 00:36:40,040
Speaker 1: we have of how the diffusion is happening and how

785
00:36:40,080 --> 00:36:42,640
Speaker 1: the neutrinos are being created, So we don't have an

786
00:36:42,640 --> 00:36:45,600
Speaker 1: absolute calibration of that either. We just have these calculations

787
00:36:45,640 --> 00:36:49,000
Speaker 1: we've done that predict the spectrum, and then those calculations

788
00:36:49,040 --> 00:36:51,640
Speaker 1: depend also on the metal. So you tweak the metals up,

789
00:36:51,680 --> 00:36:53,480
Speaker 1: you get one spectrum. You tweak the metals down, you

790
00:36:53,520 --> 00:36:55,920
Speaker 1: get another spectrum. So we can tweak the amount of

791
00:36:55,920 --> 00:36:58,680
Speaker 1: metals we put into these calculations to match what we see,

792
00:36:58,920 --> 00:37:01,000
Speaker 1: and then we think, well, let's the most likely value

793
00:37:01,000 --> 00:37:02,080
Speaker 1: of the metal in the sun.

794
00:37:03,280 --> 00:37:05,880
Speaker 2: So then what does this neutrino method say about the

795
00:37:05,920 --> 00:37:06,680
Speaker 2: metals in the sun.

796
00:37:06,880 --> 00:37:10,640
Speaker 1: So unfortunately, this method isn't super precise. It slightly favors

797
00:37:10,880 --> 00:37:13,680
Speaker 1: the higher metal scenario, so like one point eight percent,

798
00:37:13,920 --> 00:37:15,920
Speaker 1: but it can't rule out the one point three percent.

799
00:37:15,920 --> 00:37:18,080
Speaker 1: It's just sort of more like a hint. It's a

800
00:37:18,120 --> 00:37:19,880
Speaker 1: little bit of a vote towards heavy metals.

801
00:37:21,280 --> 00:37:25,440
Speaker 2: So then we have three competing methods and they all

802
00:37:25,480 --> 00:37:28,120
Speaker 2: say something slightly different. How are we going to figure

803
00:37:28,120 --> 00:37:28,879
Speaker 2: out which one's right.

804
00:37:28,880 --> 00:37:31,320
Speaker 1: We're going to dig in and question all of our assumptions,

805
00:37:31,400 --> 00:37:34,160
Speaker 1: understand where we might have overlooked something. We're going to

806
00:37:34,239 --> 00:37:39,200
Speaker 1: do more experiments, collect more data, these neutrino experiments. Specifically,

807
00:37:39,320 --> 00:37:41,160
Speaker 1: this is sort of like the first run, the first

808
00:37:41,200 --> 00:37:43,960
Speaker 1: gasp of the data. As that runs longer and longer,

809
00:37:43,960 --> 00:37:46,520
Speaker 1: it little bit more and more precise and maybe sharpen

810
00:37:46,600 --> 00:37:49,440
Speaker 1: our understanding. But this is really crucial that we figure

811
00:37:49,440 --> 00:37:51,040
Speaker 1: this out because the Sun is sort of like our

812
00:37:51,160 --> 00:37:54,440
Speaker 1: yardstick for the rest of the universe. For other stars,

813
00:37:54,480 --> 00:37:56,640
Speaker 1: we have no hope. But like looking at sound waves

814
00:37:56,640 --> 00:37:58,520
Speaker 1: on the surface, we can only look at the light

815
00:37:58,560 --> 00:38:01,480
Speaker 1: from those stars. Compare the light from those stars to

816
00:38:01,520 --> 00:38:03,680
Speaker 1: the light we get from the Sun, and we use

817
00:38:03,719 --> 00:38:06,239
Speaker 1: that to infer what's in them. Our whole estimate for

818
00:38:06,280 --> 00:38:09,040
Speaker 1: what's out there in the universe is based on what's

819
00:38:09,120 --> 00:38:11,200
Speaker 1: in the sun. If we were wrong about what's in

820
00:38:11,200 --> 00:38:14,080
Speaker 1: the sun, then we were wrong about the whole universe.

821
00:38:14,360 --> 00:38:16,640
Speaker 2: Well, unless it turns out that these other ways to

822
00:38:16,680 --> 00:38:19,680
Speaker 2: measure what's in the sun are wrong, and maybe the

823
00:38:19,800 --> 00:38:22,439
Speaker 2: one that you can't apply to other stars is right.

824
00:38:22,920 --> 00:38:25,319
Speaker 1: Yeah, absolutely, it could be, or it could be that

825
00:38:25,360 --> 00:38:27,480
Speaker 1: we don't understand what's inside the sun and how this

826
00:38:27,520 --> 00:38:30,839
Speaker 1: all works, and they're both wrong. Either way, we'd love

827
00:38:30,880 --> 00:38:33,160
Speaker 1: to understand better what's in the sun because it helps

828
00:38:33,239 --> 00:38:35,719
Speaker 1: us understand what's out there in the universe. It also

829
00:38:35,800 --> 00:38:38,920
Speaker 1: really helps us understand the fate of all of those stars.

830
00:38:39,400 --> 00:38:42,400
Speaker 1: Even though the stars are mostly not metal, those metals

831
00:38:42,440 --> 00:38:45,680
Speaker 1: can really influence whether those stars have planets around them,

832
00:38:45,880 --> 00:38:48,560
Speaker 1: how long those stars will live, and how they will die.

833
00:38:48,920 --> 00:38:52,719
Speaker 2: Ooh wait, what's the connection between the metals in the

834
00:38:52,760 --> 00:38:54,200
Speaker 2: star and their planets?

835
00:38:54,600 --> 00:38:56,799
Speaker 1: I knew you wanted to talk about aliens, right.

836
00:38:56,680 --> 00:38:58,399
Speaker 2: No, No, I just ask about the planets. I didn't

837
00:38:58,400 --> 00:39:01,600
Speaker 2: say anything about aliens. Don't protect your alien fetish on me.

838
00:39:01,719 --> 00:39:05,680
Speaker 1: Man, Who do you think is living on those planets? Man?

839
00:39:06,160 --> 00:39:11,560
Speaker 2: Nobody? Maybe alg plants heavy metal bands. Nobody said anything

840
00:39:11,560 --> 00:39:13,040
Speaker 2: about aliens. Daniels, All right, well.

841
00:39:12,960 --> 00:39:15,960
Speaker 1: I'm about to okay, get ready, Well, the more metal

842
00:39:15,960 --> 00:39:19,200
Speaker 1: there is in the initial cloud that forms that solar system.

843
00:39:19,320 --> 00:39:21,600
Speaker 1: The more metal there's going to be for making planets,

844
00:39:22,040 --> 00:39:23,880
Speaker 1: and the more metal there is, the more likely you

845
00:39:23,920 --> 00:39:27,239
Speaker 1: are to seed something that's not just the star. You

846
00:39:27,280 --> 00:39:29,640
Speaker 1: have this huge collapse in cloud. Why doesn't it all

847
00:39:29,760 --> 00:39:32,960
Speaker 1: just become a star? If some little seed near the

848
00:39:33,000 --> 00:39:35,600
Speaker 1: star can form fast enough to make its own little

849
00:39:35,600 --> 00:39:38,520
Speaker 1: gravitational well, it can gather up a bunch of stuff

850
00:39:38,640 --> 00:39:41,160
Speaker 1: and get into orbit and avoid collapsing into the star.

851
00:39:41,640 --> 00:39:44,120
Speaker 1: Do that you need a little density seed. And so

852
00:39:44,600 --> 00:39:47,560
Speaker 1: stars with more metal in them tend to have more

853
00:39:47,640 --> 00:39:51,200
Speaker 1: planets around them as well, rocky planets and giant.

854
00:39:50,800 --> 00:39:53,279
Speaker 2: Planets, we think, or we know this for sure, Like,

855
00:39:53,320 --> 00:39:54,880
Speaker 2: have we measured this out there?

856
00:39:55,000 --> 00:39:57,399
Speaker 1: We've measured this out there because we've seen planets around

857
00:39:57,480 --> 00:40:00,800
Speaker 1: other stars and so we've seen this correlation. Stars whose

858
00:40:00,880 --> 00:40:04,080
Speaker 1: light indicates more metal in them also tend to have

859
00:40:04,120 --> 00:40:05,359
Speaker 1: more planets around them.

860
00:40:05,440 --> 00:40:11,040
Speaker 2: So there's a correlation between melicity and number of planets potentially.

861
00:40:10,600 --> 00:40:12,560
Speaker 1: No, that's something we've measured. Of course, we have a

862
00:40:12,560 --> 00:40:14,919
Speaker 1: biased view of all the planets out there. We can't

863
00:40:14,920 --> 00:40:17,000
Speaker 1: see all the kinds of planets. We're not great at

864
00:40:17,000 --> 00:40:19,840
Speaker 1: seeing some kinds of planets. We can only see planets

865
00:40:19,880 --> 00:40:22,440
Speaker 1: under certain conditions, et cetera, et cetera. So this is

866
00:40:22,440 --> 00:40:24,279
Speaker 1: sort of an initial thing, but it's a correlation that

867
00:40:24,280 --> 00:40:26,640
Speaker 1: we've noticed and also one that makes sense. Right, it

868
00:40:26,680 --> 00:40:29,200
Speaker 1: fits in with our model for householar systems form.

869
00:40:29,480 --> 00:40:31,160
Speaker 2: All right, Well, I guess how are we going to

870
00:40:31,239 --> 00:40:33,839
Speaker 2: figure out what's in our sun? Then? Is there going

871
00:40:33,880 --> 00:40:35,960
Speaker 2: to be a conclusive proof at some point? Like are

872
00:40:35,960 --> 00:40:37,759
Speaker 2: we going to be able to maybe dip into the

873
00:40:37,800 --> 00:40:39,000
Speaker 2: sun and get a scoop of it?

874
00:40:40,080 --> 00:40:42,080
Speaker 1: That would be awesome. We were thinking about sending your

875
00:40:42,160 --> 00:40:44,520
Speaker 1: band over to visit the sun. Are you guys available?

876
00:40:45,000 --> 00:40:45,720
Speaker 1: Who's your agent?

877
00:40:46,000 --> 00:40:48,880
Speaker 2: Well, it depends how much are you paying and what's

878
00:40:48,920 --> 00:40:52,799
Speaker 2: the budget. Will there be green Eminem's in the green room?

879
00:40:53,320 --> 00:40:55,319
Speaker 1: I thought it was brown Eminem's in the green room?

880
00:40:55,480 --> 00:40:56,960
Speaker 2: Well, I mean, I think the whole point is that

881
00:40:57,000 --> 00:40:58,799
Speaker 2: we get to choose what kind of mmms are in

882
00:40:58,840 --> 00:41:01,800
Speaker 2: the waiting room.

883
00:41:01,840 --> 00:41:04,400
Speaker 1: All right, we'll work on the budget, but this is

884
00:41:04,440 --> 00:41:07,520
Speaker 1: not something that we are likely to figure out directly.

885
00:41:07,800 --> 00:41:10,240
Speaker 1: It's always going to be a game of improving our models,

886
00:41:10,520 --> 00:41:13,200
Speaker 1: comparing the model's predictions to what we see out there

887
00:41:13,200 --> 00:41:15,400
Speaker 1: in the universe and then seeing if we get it

888
00:41:15,400 --> 00:41:17,160
Speaker 1: to tell a coherent story.

889
00:41:17,239 --> 00:41:19,799
Speaker 2: Can we send something into the sun, like have something

890
00:41:19,840 --> 00:41:21,799
Speaker 2: fall into the Sun, and as it falls and gets

891
00:41:21,880 --> 00:41:23,640
Speaker 2: destroyed and maybe tells us what's in the.

892
00:41:23,600 --> 00:41:27,200
Speaker 1: Sun potentially with some technological advances. As I know, you know,

893
00:41:27,520 --> 00:41:30,400
Speaker 1: our recent Parker solar probe got pretty close to the

894
00:41:30,400 --> 00:41:33,080
Speaker 1: Sun but almost got toasted. It's very difficult to even

895
00:41:33,120 --> 00:41:35,719
Speaker 1: get that close to the Sun, and it was nowhere

896
00:41:35,960 --> 00:41:39,839
Speaker 1: near being able to actually sample something. On the other hand,

897
00:41:39,880 --> 00:41:42,480
Speaker 1: we're sort of already in the Sun in one sense

898
00:41:42,880 --> 00:41:45,160
Speaker 1: because where it is the edge of the Sun, the

899
00:41:45,200 --> 00:41:47,000
Speaker 1: Sun starts out very dense and then gets more and

900
00:41:47,040 --> 00:41:50,160
Speaker 1: more dilute. Then it's got this huge extended corona and

901
00:41:50,200 --> 00:41:52,960
Speaker 1: the wind. So we're already sort of sampling stuff from

902
00:41:52,960 --> 00:41:55,560
Speaker 1: the Sun. So it's possible that like the solar wind

903
00:41:55,600 --> 00:41:58,520
Speaker 1: itself might have clues we can use to figure out

904
00:41:58,760 --> 00:42:02,280
Speaker 1: what's in the Sun. Energy of those particles could potentially

905
00:42:02,320 --> 00:42:04,799
Speaker 1: be sensitive to the metallicity of the Sun.

906
00:42:05,600 --> 00:42:08,160
Speaker 2: Well, it's kind of interesting that, like we only have

907
00:42:08,239 --> 00:42:11,080
Speaker 2: one star close to us, we be able to run

908
00:42:11,120 --> 00:42:14,040
Speaker 2: these experiments and verify our models of what goes on

909
00:42:14,160 --> 00:42:16,799
Speaker 2: in any star, and so we're sort of hoping that

910
00:42:16,880 --> 00:42:19,640
Speaker 2: our Sun is not super atypical or weird.

911
00:42:19,880 --> 00:42:22,560
Speaker 1: Yeah, exactly, And we know that our star is unusual

912
00:42:22,560 --> 00:42:25,000
Speaker 1: in some sense. It's more massive than your typical star.

913
00:42:25,360 --> 00:42:27,880
Speaker 1: Most of the stars out there are red dwarfs. But

914
00:42:27,920 --> 00:42:30,680
Speaker 1: it's also in the sort of unusually good position to

915
00:42:30,719 --> 00:42:33,439
Speaker 1: sample the average kind of stuff. In the Milky Way.

916
00:42:33,760 --> 00:42:36,480
Speaker 1: We're like halfway from the Milky Way center to the

917
00:42:36,680 --> 00:42:39,680
Speaker 1: edge of the disk of stars, and most stars out

918
00:42:39,680 --> 00:42:42,040
Speaker 1: there in the universe are in big galaxies like the

919
00:42:42,080 --> 00:42:44,520
Speaker 1: Milky Way, So the Sun is sort of a scoop

920
00:42:44,560 --> 00:42:47,759
Speaker 1: of typical material, we think, so understanding what's in the

921
00:42:47,800 --> 00:42:51,240
Speaker 1: Sun will really help us understand what's in the universe.

922
00:42:51,080 --> 00:42:56,120
Speaker 2: And how heavy metal aliens might be. Isn't that the

923
00:42:56,120 --> 00:42:58,080
Speaker 2: whole point of this episode, Daniel.

924
00:42:58,000 --> 00:43:00,319
Speaker 1: Yes, exactly. We were just working up to that one

925
00:43:00,400 --> 00:43:01,240
Speaker 1: joke the whole.

926
00:43:01,000 --> 00:43:06,920
Speaker 2: Time, all right. Well, another example of how there are

927
00:43:07,000 --> 00:43:10,360
Speaker 2: still big mystories. Even in our own heart of the

928
00:43:10,440 --> 00:43:13,960
Speaker 2: Solar system, the Sun, we sort of don't really know

929
00:43:14,120 --> 00:43:17,399
Speaker 2: what it's actually made out of, and even though it's

930
00:43:17,400 --> 00:43:20,720
Speaker 2: so close we can actually go in there and figure

931
00:43:20,760 --> 00:43:23,000
Speaker 2: it out ourselves directly. We have to find all these

932
00:43:23,040 --> 00:43:26,480
Speaker 2: clever ways to infer what's inside the sun, and.

933
00:43:26,520 --> 00:43:30,040
Speaker 1: These basic questions about what's in our own backyard, in fact,

934
00:43:30,040 --> 00:43:32,319
Speaker 1: the whole universe. They tell us what's likely to be

935
00:43:32,400 --> 00:43:35,480
Speaker 1: out there in the universe, and also how it all

936
00:43:35,520 --> 00:43:39,160
Speaker 1: will end. Stars with more metallinem are more likely to

937
00:43:39,239 --> 00:43:42,279
Speaker 1: form neutron stars rather than black holes, and so the

938
00:43:42,320 --> 00:43:44,520
Speaker 1: fate of all those stars we see up there in

939
00:43:44,520 --> 00:43:47,359
Speaker 1: the night sky could depend on these measurements of what's

940
00:43:47,400 --> 00:43:48,520
Speaker 1: in our backyard.

941
00:43:48,840 --> 00:43:52,160
Speaker 2: We hope you enjoyed that. Thanks for joining us, See

942
00:43:52,160 --> 00:43:52,600
Speaker 2: you next tent.

943
00:43:57,440 --> 00:44:00,640
Speaker 1: For more science and curiosity, come find us on social media,

944
00:44:00,719 --> 00:44:05,240
Speaker 1: where we answer questions and post videos. We're on Twitter, Discorg, Insta,

945
00:44:05,360 --> 00:44:09,080
Speaker 1: and now TikTok. Thanks for listening, and remember that Daniel

946
00:44:09,080 --> 00:44:12,560
Speaker 1: and Jorge Explain the Universe is a production of iHeartRadio.

947
00:44:12,840 --> 00:44:18,000
Speaker 1: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

948
00:44:18,080 --> 00:44:20,440
Speaker 1: or wherever you listen to your favorite shows.