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Speaker 1: Hey, Daniel, you're kind of a neat freak, aren't you.

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Speaker 2: I do like to keep my laptop nicely, well dusted.

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Speaker 1: The weight dust it like you put dust in it,

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Speaker 1: or you take out dust, or you wipe dust out

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Speaker 1: of it.

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Speaker 2: Good question. I mean, I like my cookies well dusted

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Speaker 2: with sugar, but my laptop keyboard well dusted with zero dust.

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Speaker 1: Yeah, household dust is less delicious, and powdered sugar is

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Speaker 1: in regular dust, like fifty percent skin cells.

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Speaker 2: That sounds like a pretty gross thing to put on

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Speaker 2: your cookies. On the other hand, it would be pretty

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Speaker 2: weird if powdered sugar just like accumulated in your.

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Speaker 1: House, it'd be pretty sweet.

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Speaker 2: We might call for some sweeping changes.

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Speaker 1: Uh, I'm glad you got to dust off that old punt.

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Speaker 2: Hi.

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Speaker 1: I'm Poor hammy cartoonas and the author of Oliver's Great

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Speaker 1: Big Universe.

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Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor

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Speaker 2: at UC Irvine, and I don't like dust as much

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Speaker 2: as astronomers do.

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Speaker 1: But do you still like it a little bit?

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Speaker 2: I like dust the way I like the sun. It's fascinating,

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Speaker 2: it's interesting, it's useful, It tells us about the cosmos.

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Speaker 2: But I don't really want it on my laptop or

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Speaker 2: on my table.

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Speaker 1: But everywhere else it's okay.

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Speaker 2: Yeah, study it from a distance, you know, the way

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Speaker 2: like I'm fascinated by cheetahs, but I don't really want

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Speaker 2: to have a cheat on my lap.

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Speaker 1: Do you carry a duster with you at all times?

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Speaker 3: Then?

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Speaker 2: I actually do have this very fancy little machine for

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Speaker 2: removing dust from your keyboard.

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Speaker 1: Is it called blowing on it? Or did you Did

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Speaker 1: you actually pay for a machine to do that?

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Speaker 2: I actually have a nice little machine. It's really quite good. Yeah,

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Speaker 2: I should call it mini made.

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Speaker 1: Wait, what is it like a vacuum?

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Speaker 2: No, it's like a little blower, you know. It replaces

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Speaker 2: those disposable cans that I thought were not very environmentally friendly,

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Speaker 2: though I do love them.

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Speaker 3: Mmm.

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Speaker 1: Oh, I see you mean like the dust between the keys,

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Speaker 1: like you want to get rid of it, like in

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Speaker 1: the nooks and crannies.

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Speaker 2: Yeah, exactly. I like a nice clean keyboard.

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Speaker 3: Oh.

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Speaker 1: I thought you meant like on your screen, because I

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Speaker 1: think you can just wipe that off.

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Speaker 2: I think you can. But probably that dust contains all

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Speaker 2: sorts of fascinating stories where each of those bits has

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Speaker 2: been But you.

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Speaker 1: Know, if you just blow the dust, it's just getting

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Speaker 1: in the air and then it's going to come back

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Speaker 1: down on your keyboard.

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Speaker 2: I know it's a cycle. Unless I'm willing to live

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Speaker 2: in a clean room, I can never escape it.

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Speaker 1: So you don't like living in clean rooms.

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Speaker 2: I don't have to wear a hairnet and booties all

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Speaker 2: the time.

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Speaker 1: No, just some of the time. But anyways, welcome for

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Speaker 1: a podcast Daniel and Jorge Explain the Universe, a production

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Speaker 1: of our Heart Radio.

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Speaker 2: In which we dive deep into the cycles of the universe,

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Speaker 2: the ones that produce massive stars and tiny grains of dust.

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Speaker 2: Everything out there in the universe has a history and

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Speaker 2: tells a story, and if we can unpack it, unravel

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Speaker 2: it and study it, you can reveal those stories and

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Speaker 2: the history of our own cosmos. To learn about the

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Speaker 2: formation of the planets and stars and the universe itself,

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Speaker 2: from the biggest clues to the tiniest speck of dust.

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Speaker 1: That's right, we blow the dust off of the universe,

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Speaker 1: trying to uncover what's underneath, What shiny surface or interesting

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Speaker 1: facts are there for us to understand and to learn about.

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Speaker 2: I love in archaeology, how every time they're going to

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Speaker 2: discover something amazing, they always have to blow dust off

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Speaker 2: of it, pull cobwebs off of it. That's like your

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Speaker 2: visual cue that you're about to learn something ancient.

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Speaker 1: Wait, wait, what do you mean?

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Speaker 2: I mean? I just watched a new Indian Jones. I guess.

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Speaker 2: So you know anytime they unde earth something from the

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Speaker 2: olden days, it's always covered in dust.

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Speaker 1: Of course, mm to see they carry a dust with

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Speaker 1: them at all times. Maybe you can buy one of

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Speaker 1: those devices and you didn't have to waste electricity.

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Speaker 2: I'd be that neat freak archaeologist. I don't think i'd

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Speaker 2: get very far in the field.

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Speaker 1: Yeah, it is a dusty universe full of amazing things,

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Speaker 1: where even the dust is interesting. In the universe.

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Speaker 2: Down here on Earth we see dust is sort of

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Speaker 2: a nuisance, something to brush out of our But out

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Speaker 2: in space dust plays a very important role in the

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Speaker 2: formation of stars and planets, and it can reveal that history.

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Speaker 2: Dust is not just a nuisance. It's a fascinating pile

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Speaker 2: of tiny clues.

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Speaker 1: So today end podcast, we'll be asking the question how

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Speaker 1: important is cosmic dust? Now? Hopefully this episode won't be

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Speaker 1: a bust.

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Speaker 2: Should we just be sweeping cosmic dust under the cosmic

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Speaker 2: rug or should we take it seriously and study it

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Speaker 2: in detail.

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Speaker 1: That's a bit of a dusty pun there, you used

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Speaker 1: it already, But yeah, it's an interesting question here cosmic dust.

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Speaker 1: I guess it's different than regular dust.

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Speaker 2: Well, I think there's fewer dead skin cells and leftover

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Speaker 2: bits of insects out there floating between the stars than

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Speaker 2: there is here on Earth. But cosmic dust also falls

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Speaker 2: to Earth.

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Speaker 1: You mean it gets sprinkled from space like powdered sugar.

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Speaker 2: Well, you know that space isn't empty, and there's dust

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Speaker 2: out there between the stars but also between the planets,

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Speaker 2: and as the Earth moves through these cosmic dust clouds,

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Speaker 2: it accumulates some of them. Some tons of dust fall

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Speaker 2: to Earth every year from interplanetary space out there in

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Speaker 2: the Solar System.

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Speaker 1: WHOA is it like dandruff space? Dandruff? Or is that

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Speaker 1: too embarrassing?

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Speaker 2: We had a whole fun episode about where this stuff

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Speaker 2: comes from. It's a bit of a mystery. There's a

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Speaker 2: recent experiment though, that tries to pin the blame on Mars.

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Speaker 2: It might be that dust storms on Mars are blowing

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Speaker 2: that stuff out into space and the Earth is flying

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Speaker 2: through Mars's dust clouds. So yeah, I guess it's all

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Speaker 2: Martian dandruff.

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Speaker 1: Yeah, Mars needs some head and shoulders.

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Speaker 2: Well first they need heads and shoulders. That'd be pretty

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Speaker 2: awesome discovery.

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Speaker 1: Yeah, or maybe just a hat that might help. But

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Speaker 1: it is an interesting question. How important is cosmic dust?

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Speaker 1: Which I guess means Daniel, that cosmic dust is important.

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Speaker 2: Cosmic dust is more important than you might think. I mean,

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Speaker 2: the word dust makes you think it's insignificant. It's just

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Speaker 2: something to be blown off of. Something else. Man, it

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Speaker 2: gets in your way, something, it messes things up, something

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Speaker 2: to be gotten rid of. But dust has clues in it.

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Speaker 2: This is like the dust here on Earth tells you

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Speaker 2: who's been living there and the insects that have been around.

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Speaker 2: Dust out in space tells you what's been happening in

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Speaker 2: the universe, because there's dust makers and dust consumers, and

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Speaker 2: dust also plays a big role in making stars and planets.

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Speaker 1: Well, you just said dust consumers out in space like

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Speaker 1: aliens who buy dust. That's what it sounds like.

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Speaker 2: Not dust customers. You know, ways in which just is

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Speaker 2: created and then dust is destroyed. I should say dust destroyers.

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Speaker 1: Oh there you go. See that's a device. I would

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Speaker 1: buy a dust destroyer.

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Speaker 2: Wait till you learn how dust is destroyed. You don't

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Speaker 2: want one of these things?

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Speaker 1: Maybe I do. Let's find out. Well, as usual, we

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Speaker 1: were wondering how many people had thought about the importance

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Speaker 1: of cosmic does and what role it has in our

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Speaker 1: search for the meaning of the universe and how it

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Speaker 1: all works.

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Speaker 2: Thanks to everybody who pitches in for this segment of

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Speaker 2: the podcast. I hear from listeners that they really enjoy

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Speaker 2: hearing your voices in your thoughts on the episode topic.

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Speaker 2: If you would like to share your voice and thoughts,

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Speaker 2: please don't be shy. Write me to Questions at Daniel

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Speaker 2: Andandjorge dot com.

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Speaker 1: So think about for a second, how important do you

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Speaker 1: think cosmic dust is. Here's what people have to say.

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Speaker 2: Stop waving from the universe. I would say that twenty

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Speaker 2: percent is planet stars, black holes, sixty percent gus, and

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Speaker 2: the rest twenty percent is dust.

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Speaker 3: I think that this is the one of those questions

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Speaker 3: that but you have to think about some things that

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Speaker 3: you usually take for granted. So I would say that

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Speaker 3: the QA is mostly composed by dust.

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Speaker 1: All right, interesting, answers here, some people seem to interpret

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Speaker 1: the questions like how significant is cosmic? Doest?

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Speaker 2: Yeah?

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Speaker 1: Like, or like how much how much of the universe

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Speaker 1: is cosmic? Does?

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Speaker 2: And they also seem to be taking it as a

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Speaker 2: leading question, like because I'm asking it, they're figuring probably

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Speaker 2: it's a big component of the universe and playing an

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Speaker 2: important role.

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Speaker 1: I see, it wouldn't be very interesting just the answer

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Speaker 1: was just like not at all or nope, nobody cares.

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Speaker 2: Yeah, Like how important are Daniel dirty socks?

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Speaker 3: Yeah?

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Speaker 2: Not interesting, not important? Move on, That wouldn't be a

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Speaker 2: very fun episode.

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Speaker 1: Let's not talk about your socks because I know you

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Speaker 1: don't wear socks, so.

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Speaker 2: Well, then it's a philosophy question, right can my socks

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Speaker 2: be unimportant if they don't even exist?

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Speaker 1: There you go, philosophy of footwear.

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Speaker 2: Somebody out there is doing a whole PhD thesis on

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Speaker 2: that topic, probably.

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Speaker 1: On your socks. On socks, and Jackie, I know you're

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Speaker 1: famous now, Daniel, but geez.

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Speaker 2: No on socks? Why they disappear where they go? Why

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Speaker 2: dryers consume them? See dryers are sock destroyers.

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Speaker 1: Nay, it turns them into dust.

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Speaker 2: Maybe it transports them to the hozone layer of the atmosphere.

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Speaker 1: So let's dig into this topic, Daniel, what is cosmic dust?

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Speaker 2: Cosmic dust is an important part of the Solar system,

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Speaker 2: though it's not a big fraction of the Solar system.

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Speaker 2: The answer from these listeners made me dig into the

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Speaker 2: question of like, actually, but is the mass budget of

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Speaker 2: the Solar system? How much of it is cosmic dust

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Speaker 2: and how much of it is made of other stuff?

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Speaker 1: So what's the breakdown?

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Speaker 2: So the Milky Way weighs about one to one and

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Speaker 2: a half trillion times the mass of the Sun. That's

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Speaker 2: like our mass unit a solar mass, and the total

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Speaker 2: Milky Way is about a trillion trillion and a half

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Speaker 2: solar masses. Now, most of that, like ninety percent of

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Speaker 2: that is dark matter. We know that the stuff that's

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Speaker 2: visible in the universe, the stuff that glows, and even

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Speaker 2: the stuff that doesn't glow that much, like rocks and

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Speaker 2: dust and asteroids, that's only like ten percent of the

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Speaker 2: mass of the Milky Way. Out there in the larger universe,

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Speaker 2: dark matter is a little bit less common than it

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Speaker 2: is here in the Milky Way. The Milky Way has

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Speaker 2: more dark matter than an average galaxy.

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Speaker 1: And I guess. How do we know these things? Like

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Speaker 1: how do we know how much the Milky Way weighs?

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Speaker 1: Do we put it on a scale or something.

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Speaker 2: We can measure the component of the Milky Way independently

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Speaker 2: and then add them up. The stars and the interstellar medium,

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Speaker 2: the black hole, all that stuff we can measure independently,

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Speaker 2: and then we can measure the total mass by looking

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Speaker 2: at how fast the Milky Way is rotating. Because stars

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Speaker 2: are like tracers, they move around the Milky Way, and

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Speaker 2: their speed is determined by the gravitational traction of everything

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Speaker 2: closer to the center than they are. Things further away

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Speaker 2: from the center on the outer shell don't affect them

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Speaker 2: at all, things on the inside do. So by reading

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Speaker 2: the speed of these stars, we can tell how much

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Speaker 2: mass they're radius encloses, and so that measures the total

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Speaker 2: mass of the Solar system. And that's how we infer

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Speaker 2: dark matter, sort of the left over bit that we

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Speaker 2: can't account for with stars and planets and gas and dust.

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Speaker 1: But we can't see all of the Milky Way right

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Speaker 1: Like we're in the Milky Way, can we really see

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Speaker 1: the full extent of it and have a good guess

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Speaker 1: about its composition?

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Speaker 2: There's a lot of uncertainty, which is why I said

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Speaker 2: one to one and a half trillion solar masses. So

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Speaker 2: that's like an uncertainty of five hundred billion solar masses.

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Speaker 2: And yeah, part of that comes from the fact that

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Speaker 2: we can't see the whole Milky Way because we're looking

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Speaker 2: through it, we're inside of it, and the Milky Way

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Speaker 2: has a good amount of dust in it, and that

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Speaker 2: dust obscures our view. So there's a whole region of

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Speaker 2: the Milky Way that we can't see very well in

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Speaker 2: many frequencies of light, and that leads to a lot

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Speaker 2: of this uncertainty. I see.

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Speaker 1: So then how much of our Milky Way is dust?

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Speaker 2: So it's like ninety percent dark matter, Then it's like

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Speaker 2: three percent stars, it's like one hundred to two hundred

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Speaker 2: billion stars. And then leftover is this stuff called the

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Speaker 2: interstellar medium, which is maybe like half a percent or

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Speaker 2: one percent of the mass of the Milky Way, and

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Speaker 2: one percent of that is dust. The interstellar medium is

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Speaker 2: mostly gas, it's like hydrogen and a little bit of helium.

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Speaker 2: So one percent of the interstellar medium, which is one

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Speaker 2: percent of the galaxy, is dust. So the dust is

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Speaker 2: like point zho one percent or maybe half of that.

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Speaker 2: It's a tiny fraction of the mass of the Milky Way.

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Speaker 1: So I guess you don't count that gas is dust, right.

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Speaker 2: That's right. And this is another example of humans putting

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Speaker 2: categories on things where really there's a smooth spectrum. If

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Speaker 2: we call it gas, it means it's like a molecule,

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Speaker 2: there's like h two floating out there, we call that gas.

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Speaker 2: If it's a larger clump of stuff, a bunch of

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Speaker 2: molecules together, little grains down like one hundred nanometers or larger,

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Speaker 2: we call that dust. Get much bigger, we start to

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Speaker 2: call you like a meteor or an asteroid or even

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Speaker 2: a planet. But in the end, there's a whole spectrum

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Speaker 2: all the way down from individual molecules which we call gas,

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Speaker 2: to larger clumps of stuff which we call dust, all

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Speaker 2: the way up to much bigger objects stars and planets.

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Speaker 1: I guess at some point you get to like pebbles, right,

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Speaker 1: and little rocks. Is there such a thing as space sand?

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Speaker 2: Well, you know this dust is made of carbon and silicates, right,

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Speaker 2: and sand is mostly silicates. So in the end, like

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Speaker 2: a lot of this space dust is kind of like

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Speaker 2: super fine grains of sand.

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Speaker 1: But then I also imagine there is sort of sand

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Speaker 1: sized grains out there in space.

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Speaker 2: There are larger pieces for sure, And so this intermedia

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Speaker 2: category we call dust is not a very big fraction

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Speaker 2: of the mass of the Milky Way. But to compare,

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Speaker 2: it's about the same mass as the central black Hole.

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Speaker 2: Point oh one percent of the Milky Way sounds like

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Speaker 2: a tiny number. It's a tiny percentage of a huge number, right,

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Speaker 2: one and a half trillion solar masses. So it comes

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Speaker 2: out to be about the mass of the central black Hole.

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Speaker 1: And so where did all this dust come from? Like

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Speaker 1: are there giant space aliens shedding of their skin?

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Speaker 2: To understand where the dust comes from, we need to

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Speaker 2: dig into a little bit more about like what is

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Speaker 2: this dust? And it's made of like a bunch of

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Speaker 2: different stuff, some tiny little portion of it, this is

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Speaker 2: really fascinating, comes from the atmospheres of stars. We know

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Speaker 2: that stars their job is to take hydrogen and helium

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Speaker 2: and lighter elements and fuse them into heavier elements, although

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Speaker 2: I have to iron and even heavier in the case

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Speaker 2: of supernova and in the atmospheres of these stars, especially

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Speaker 2: when they get really really big and near the end

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Speaker 2: of their life. Their atmospheres produce these little grains. They're

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Speaker 2: like coalesce as they cool, and the outflow in the

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Speaker 2: atmosphere of these stars. That's sort of like one source

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Speaker 2: of this stuff. But if you look out into the

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Speaker 2: universe and study this stuff, most of it is not

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Speaker 2: these presolar grains, these like pristine little blobs made in

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Speaker 2: the atmospheres of stars. Most of it's been like reprocessed,

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Speaker 2: like shattered and ground up and reformed into new bits.

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Speaker 1: Interesting just from like the churning of space, of stuff

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Speaker 1: in space.

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Speaker 2: Just from the churning of space. It turns out that

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Speaker 2: you can't just hang out as a grain in the

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Speaker 2: middle of space. There are processes happening out there. There

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Speaker 2: are processes that destroy dust and processes that reform it.

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Speaker 2: The dust destroyers that are out there. It sounds like,

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Speaker 2: you know, some big alien ship coming along to clean

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Speaker 2: up the universe, but actually it's shock waves from supernova.

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Speaker 2: When supernova collapse and then explode, they produce these huge

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Speaker 2: shock waves, massive amounts of energy, gamma, rays, neutrinos, all

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Speaker 2: sorts of stuff, and that comes along and it shatters

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Speaker 2: these grains, destroying the dust and breaking it like back

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Speaker 2: down into gas.

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Speaker 1: Well you know they say space is just a big vacuum,

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Speaker 1: so those are just suckle. Anyways, So you were saying

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Speaker 1: that dust is important in the universe. Is it important

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Speaker 1: to the universe or just to our understanding or to

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Speaker 1: our search for answers about the universe?

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Speaker 2: Well both, Like the history of dust tells us what's

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Speaker 2: happened out there in the universe. You can take each

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Speaker 2: individual solar grain if it survived this like interstellar shattering process,

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Speaker 2: and some of them have, and you can trace it

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Speaker 2: back to an individual star. Like every star has a

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Speaker 2: different mixture of elements and a different mixture of isotopes,

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Speaker 2: so they leave special fingerprints in their solar grains, and

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Speaker 2: so like ular grain can tell you, like what that

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Speaker 2: star was. It's like a little sample from that star.

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Speaker 2: And some of them are made during supernova and capture

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Speaker 2: elements and isotopes that only exist, we think, in the

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Speaker 2: atmospheres of supernova during those brief moments that are super

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Speaker 2: energetic and can tell us about the formation of heavy

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Speaker 2: elements and what's going on in supernova. So there are

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Speaker 2: these amazing capsules that tell us about the history of

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Speaker 2: the universe.

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Speaker 1: But I think maybe you don't mean like each individual grain,

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Speaker 1: do you look? You maybe need like a population or

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Speaker 1: like a cloud of this dust to sort of know

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Speaker 1: what the star was like.

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Speaker 2: Well, each individual grain tells you something about that star.

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Speaker 2: Not every grain produced by the star is identical, right,

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Speaker 2: and the star has a variety of stuff in it,

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Speaker 2: but each one traces back to an individual star.

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Speaker 1: Just each grain would be made out of different things.

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Speaker 2: Yeah, each star would make different kinds of grains. There's

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Speaker 2: going to be some overlap. It's not completely unique, right,

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Speaker 2: But each star is made out of different kinds of stuff,

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Speaker 2: different elements, different mixtures. Each star is a slightly different

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Speaker 2: mass and temperature and so produces different mixtures of stuff

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Speaker 2: and different isotopes, and so the grains produced by each

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Speaker 2: star are different.

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Speaker 1: Like an individual grain would have different things in it

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Speaker 1: and different signatures in it.

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Speaker 2: Yeah, exactly. The isotopes found in an individual grain tell

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Speaker 2: you about the star that it came from.

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Speaker 1: Mmmm. Interesting, So how is it important to the universe itself?

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Speaker 1: Because it doesn't seem like it weighs a lot in

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Speaker 1: the Milca way, So maybe I wonder if it has

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Speaker 1: a big role in you know, the dynamics of space.

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Speaker 2: It does play a big role in the dynamics of

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Speaker 2: space sort of for two reasons. One is that stuff

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Speaker 2: heavier than gas is the reason that we have like

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Speaker 2: planets and stars and stuff like that. Like the Earth

376
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Speaker 2: is mostly made out of stuff that's not just hydrogen

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Speaker 2: and helium, right, and that's cosmic dust gathered together to

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Speaker 2: form planets. So most of the rocky stuff of the

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Speaker 2: Solar system came originally from what we would call cosmic dust, right,

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Speaker 2: those heavier elements that are created by stars and spewed

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Speaker 2: out into space. And also we think that this cosmic

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Speaker 2: dust plays a role in the formation of solar systems.

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Speaker 2: You have a huge gas cloud that eventually collapses into

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Speaker 2: a bunch of stars. Why does it collapse. It collapses

385
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Speaker 2: because it's a little spot here that's denser, that's heavier,

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Speaker 2: that's cosmic dust. Man, Those are like the iron grains

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Speaker 2: and the little bits of heavy elements floating around that

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Speaker 2: seed that gravitational collapse.

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Speaker 1: Wait, are you saying the Bible was right? We all

390
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Speaker 1: come from dust, from dust to dust.

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Speaker 2: And even ashes, right, star ashes.

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Speaker 1: Cool And so then how does it help us study

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Speaker 1: the universe or how does it not help us study

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Speaker 1: the universe.

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Speaker 2: Yeah, it both hurts our ability to study the universe

396
00:18:01,280 --> 00:18:04,200
Speaker 2: and helps us. Like it prevents us from seeing things

397
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Speaker 2: in the universe because it absorbs light and it blocks

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Speaker 2: our view. The center of the Milky Way, which is

399
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Speaker 2: choked with dust, is famously called by astronomers the zone

400
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Speaker 2: of avoidance because they have to look away from that region.

401
00:18:16,040 --> 00:18:18,320
Speaker 2: You can't see through the center of the Milky Way

402
00:18:18,760 --> 00:18:21,000
Speaker 2: in optical lights, so you can't see what's on the

403
00:18:21,080 --> 00:18:23,800
Speaker 2: other side of the galaxy very easily. So it's sort

404
00:18:23,840 --> 00:18:26,560
Speaker 2: of a pain for astronomers, but it also captures this

405
00:18:26,720 --> 00:18:29,439
Speaker 2: history right, And in order to understand the cycles of

406
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Speaker 2: star formation in the universe, we do have to understand

407
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Speaker 2: the cosmic dust because the cosmic dust plays a role

408
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Speaker 2: in the formation of those stars and is also then

409
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Speaker 2: destroyed by the supernovas and then reforms. It's all part

410
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Speaker 2: of the cycle of the Milky Way. You might imagine

411
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Speaker 2: the Milky Way is just like a bunch of stars

412
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Speaker 2: floating in space basically doing nothing, but it's churning and burning.

413
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Speaker 2: This stuff going on just sort of much longer time

414
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Speaker 2: scales than we're used to thinking about.

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Speaker 1: Hmm. Interesting all right, Well, let's get into how we

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Speaker 1: know where the dust in the universe is and the

417
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Speaker 1: very important question where does it all come from? Who's

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Speaker 1: making this mess in the universe. So let's dig into that,

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Speaker 1: But first let's take a quick break. All right, we're

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Speaker 1: talking about cosmic dust, which is not a drug, I imagine,

421
00:19:25,160 --> 00:19:28,200
Speaker 1: so it sounds like it might be something you'd sell

422
00:19:28,200 --> 00:19:28,840
Speaker 1: on the streets.

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Speaker 2: I don't know. If you walk down the street in

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Speaker 2: Berkeley and you ask people for cosmic dust, I'm pretty

425
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Speaker 2: sure they'll sell you something.

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Speaker 1: They'll sell you something. But we're talking about the dust's

427
00:19:37,480 --> 00:19:40,879
Speaker 1: out there in space between the stars, and it's important

428
00:19:41,080 --> 00:19:44,000
Speaker 1: because we're all made out of dust. Stars and planets,

429
00:19:44,000 --> 00:19:47,639
Speaker 1: they're all essentially come from dust that gravity pulls together,

430
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Speaker 1: and so it's important for that reason. But it also

431
00:19:50,680 --> 00:19:53,760
Speaker 1: sort of helps us understand the origins of stars in

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Speaker 1: the universe.

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Speaker 2: Right, even though it's tiny, it's a little bitty part

434
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Speaker 2: of the mass budget of the Solar system. It tells

435
00:20:00,200 --> 00:20:02,280
Speaker 2: about how things work and it plays a role in

436
00:20:02,320 --> 00:20:03,480
Speaker 2: getting those things started.

437
00:20:03,560 --> 00:20:05,800
Speaker 1: But I imagine maybe at some point in the universe's

438
00:20:05,840 --> 00:20:09,360
Speaker 1: history dust it was all dust, basically, right, That's where

439
00:20:09,359 --> 00:20:11,640
Speaker 1: all those stars came from No, I guess you went

440
00:20:11,680 --> 00:20:15,040
Speaker 1: from gas to stars and then those made dust exactly.

441
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Speaker 2: We think that the universe began and dust lists right.

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Speaker 2: So it's actually an interesting open question in astronomy right now.

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Speaker 2: It is like when was the first dust made? People

444
00:20:25,040 --> 00:20:27,720
Speaker 2: really want to understand the process by which dust is

445
00:20:27,800 --> 00:20:32,440
Speaker 2: created and destroyed and helps form new stars, and there's

446
00:20:32,440 --> 00:20:34,240
Speaker 2: a lot of open questions out there. We don't really

447
00:20:34,240 --> 00:20:37,240
Speaker 2: fully understand the process of it. But we're pretty sure

448
00:20:37,280 --> 00:20:40,320
Speaker 2: that the universe began with just hydrogen and helium and

449
00:20:40,359 --> 00:20:44,240
Speaker 2: the tiny trace elements of things heavier and no larger

450
00:20:44,320 --> 00:20:47,240
Speaker 2: molecules of course, and it's only when stars began to

451
00:20:47,280 --> 00:20:49,240
Speaker 2: burn that dust was created.

452
00:20:49,359 --> 00:20:51,439
Speaker 1: But I wonder if in the Big Band, you know,

453
00:20:51,480 --> 00:20:54,239
Speaker 1: things were so intense, there was so much pressure, there

454
00:20:54,320 --> 00:20:57,399
Speaker 1: was so much violent processes going on, so many of

455
00:20:57,400 --> 00:21:00,480
Speaker 1: those that I wonder if some hydrogens aret it e

456
00:21:00,680 --> 00:21:04,000
Speaker 1: merging together and make dust without any stars? Is that possible?

457
00:21:04,160 --> 00:21:06,840
Speaker 2: With the earliest dust we've seen is like several hundred

458
00:21:06,920 --> 00:21:09,280
Speaker 2: million years after the Big Bang, and it's possible that

459
00:21:09,400 --> 00:21:13,720
Speaker 2: hydrogen formed and crystallized somehow earlier on. I don't think

460
00:21:13,720 --> 00:21:15,600
Speaker 2: we would call that cosmic dust. Though if it's just

461
00:21:15,680 --> 00:21:18,919
Speaker 2: pure hydrogen, probably you just call that hydrogen crystals. I

462
00:21:18,960 --> 00:21:20,960
Speaker 2: think to be called dust probably needs to have some

463
00:21:21,080 --> 00:21:23,680
Speaker 2: like carbon and some silicon and some heavier elements in it.

464
00:21:23,720 --> 00:21:25,760
Speaker 1: But I mean, could a little bit of a carbon

465
00:21:25,800 --> 00:21:28,640
Speaker 1: and silicon have formed in the big during the Big Bang?

466
00:21:28,760 --> 00:21:31,919
Speaker 2: Big Bang nuclear synthesis is a pretty precise science, and

467
00:21:32,000 --> 00:21:34,240
Speaker 2: it tells us, based on the temperature and like the

468
00:21:34,320 --> 00:21:37,960
Speaker 2: cork density, exactly how much of what was made. And

469
00:21:38,240 --> 00:21:41,479
Speaker 2: we think that it's almost overwhelmingly hydrogen, with just tiny

470
00:21:41,600 --> 00:21:44,879
Speaker 2: trace elements of helium and then little tiny, anty bitty

471
00:21:44,880 --> 00:21:49,040
Speaker 2: bits of heavier stuff carbon. Probably not because carbon requires

472
00:21:49,040 --> 00:21:53,240
Speaker 2: the merging of three helium simultaneously. Because lithium is so unstable,

473
00:21:53,680 --> 00:21:56,240
Speaker 2: so very unlikely that any carbon was formed, but you

474
00:21:56,240 --> 00:21:59,199
Speaker 2: can't say no, it's possible there were tiny, tiny grains

475
00:21:59,240 --> 00:22:00,920
Speaker 2: of carbon form during the Big Bang.

476
00:22:01,440 --> 00:22:05,080
Speaker 1: So there could be primordial dust out there, like og dust.

477
00:22:05,359 --> 00:22:08,960
Speaker 2: That's right, The most ancient dust is possible, though the

478
00:22:09,000 --> 00:22:11,840
Speaker 2: oldest dust we've ever seen is a few hundred million

479
00:22:11,960 --> 00:22:13,240
Speaker 2: years after the Big Bang.

480
00:22:13,280 --> 00:22:15,200
Speaker 1: All right, Well, that brings us to our next question,

481
00:22:15,240 --> 00:22:17,040
Speaker 1: which is, how do we know where the dust in

482
00:22:17,040 --> 00:22:19,520
Speaker 1: the universe is. It doesn't glow in space, right, It.

483
00:22:19,480 --> 00:22:21,680
Speaker 2: Actually kind of does glow in space, not the way

484
00:22:21,720 --> 00:22:24,800
Speaker 2: that stars do. Right. Stars create their own light through fusion.

485
00:22:24,920 --> 00:22:27,400
Speaker 2: They light up the whole universe. But everything out there

486
00:22:27,400 --> 00:22:30,080
Speaker 2: has a temperature, and everything that has a temperature glows.

487
00:22:30,440 --> 00:22:33,720
Speaker 2: Even the Earth glows. Right. It gives off infrared radiation,

488
00:22:34,280 --> 00:22:37,160
Speaker 2: and so dust glows in the very very infrared because

489
00:22:37,240 --> 00:22:40,440
Speaker 2: dust is pretty cold. So you can see the dust

490
00:22:40,480 --> 00:22:43,439
Speaker 2: if you use telescopes that can see infrared light and

491
00:22:43,480 --> 00:22:46,280
Speaker 2: so like the Spitzer Space Telescope and a James Web

492
00:22:46,320 --> 00:22:49,399
Speaker 2: Space telescope. These things out there can see dust in

493
00:22:49,440 --> 00:22:53,159
Speaker 2: our galaxy and in other galaxies by its thermal emissions.

494
00:22:54,000 --> 00:22:55,760
Speaker 1: Like I guess you could tell where there was a

495
00:22:55,800 --> 00:22:57,880
Speaker 1: lot of dust and where there isn't a lot of dust.

496
00:22:57,960 --> 00:23:00,359
Speaker 2: Yeah, exactly. You can't see an individual grain. You can

497
00:23:00,400 --> 00:23:04,119
Speaker 2: see like huge clouds of dust here and there. You

498
00:23:04,160 --> 00:23:06,480
Speaker 2: can see it glowing in the very far infrared. You

499
00:23:06,520 --> 00:23:09,119
Speaker 2: can also see dust by how it blocks light. Like

500
00:23:09,160 --> 00:23:11,600
Speaker 2: we think we understand how stars glow and the light

501
00:23:11,640 --> 00:23:14,280
Speaker 2: that they give off, and dust blocks that light. You know,

502
00:23:14,320 --> 00:23:17,719
Speaker 2: it absorbs some frequencies of it, it reflects other frequencies of it,

503
00:23:18,119 --> 00:23:21,320
Speaker 2: and so by looking at what astronomers call the extinction curve,

504
00:23:21,520 --> 00:23:24,560
Speaker 2: like where's light being blocked, they can measure how much

505
00:23:24,640 --> 00:23:26,600
Speaker 2: dust there is between us and something.

506
00:23:27,400 --> 00:23:29,880
Speaker 1: So we measure it by how it much it blocks light,

507
00:23:30,080 --> 00:23:31,600
Speaker 1: not how much it reflects light.

508
00:23:31,720 --> 00:23:33,639
Speaker 2: We measure it by how much it blocks light and

509
00:23:33,720 --> 00:23:36,440
Speaker 2: also emits a little bit of light in the infrared,

510
00:23:36,960 --> 00:23:39,360
Speaker 2: so it depends a lot on the frequency it will reflect.

511
00:23:39,400 --> 00:23:43,040
Speaker 2: Blue light mostly infrared light can mostly pass through dust

512
00:23:43,160 --> 00:23:45,720
Speaker 2: shorter frequencies where the light has like roughly the wavelength

513
00:23:45,800 --> 00:23:49,000
Speaker 2: of the dust that will get reflected or absorbed. So

514
00:23:49,040 --> 00:23:51,640
Speaker 2: when light passes through a dust cloud, it basically gets

515
00:23:51,720 --> 00:23:55,040
Speaker 2: reddened because the blue light gets reflected and the red

516
00:23:55,119 --> 00:23:56,000
Speaker 2: light makes it through.

517
00:23:57,040 --> 00:23:58,879
Speaker 1: It's a little bit of the opposite of what happens

518
00:23:58,920 --> 00:24:00,760
Speaker 1: here during the sunset. No, it's the same.

519
00:24:00,840 --> 00:24:03,240
Speaker 2: It's the same. The light gets reddened, right, the atmosphere

520
00:24:03,320 --> 00:24:06,200
Speaker 2: tends to reflect blue light, so the sky looks blue

521
00:24:06,280 --> 00:24:09,280
Speaker 2: because in direct sunlight it's scattered down to your eye.

522
00:24:09,400 --> 00:24:11,280
Speaker 2: That at sunset, the light is coming straight at you

523
00:24:11,359 --> 00:24:13,480
Speaker 2: and the blue light is being reflected away and you're

524
00:24:13,520 --> 00:24:14,760
Speaker 2: seeing the red light. Mm.

525
00:24:15,119 --> 00:24:17,640
Speaker 1: It filters like it filters out blue light.

526
00:24:17,560 --> 00:24:20,439
Speaker 2: M hmm, exactly, it filters out blue light. And so

527
00:24:20,480 --> 00:24:23,000
Speaker 2: when astronomers look out into the sky, they can see

528
00:24:23,040 --> 00:24:25,720
Speaker 2: that some stars appear to be dimmed, and they appear

529
00:24:25,760 --> 00:24:28,879
Speaker 2: to be dimmed differently across the spectrum. Right, It's not

530
00:24:28,960 --> 00:24:31,159
Speaker 2: just like the whole star is dimmer, which might mean

531
00:24:31,160 --> 00:24:33,639
Speaker 2: it just further away, but it's dimmed more in the

532
00:24:33,680 --> 00:24:36,560
Speaker 2: red than in the blue. So these extinction curves are

533
00:24:36,600 --> 00:24:39,280
Speaker 2: really important for astronomers to study because every time they're

534
00:24:39,320 --> 00:24:40,879
Speaker 2: looking at something in the universe, they want to know,

535
00:24:40,960 --> 00:24:43,400
Speaker 2: like how much dust are we looking through? How much

536
00:24:43,440 --> 00:24:45,639
Speaker 2: is dust distorting what we're seeing?

537
00:24:46,560 --> 00:24:49,800
Speaker 1: So technically, does that mean that dust, this space dust

538
00:24:49,840 --> 00:24:52,240
Speaker 1: is blue like if you were well, when you sort

539
00:24:52,240 --> 00:24:53,560
Speaker 1: of look at it, it's blueish.

540
00:24:53,800 --> 00:24:56,000
Speaker 2: I guess it reflects blue light. It glows in the

541
00:24:56,080 --> 00:24:59,200
Speaker 2: far infrared, but it reflects blue light, so I guess

542
00:24:59,240 --> 00:25:00,360
Speaker 2: that would make it kind blue.

543
00:25:00,440 --> 00:25:03,119
Speaker 1: Yeah, And have we ever like got in a sample

544
00:25:03,160 --> 00:25:05,040
Speaker 1: of dust, Like, have we ever gone out there and

545
00:25:05,320 --> 00:25:08,880
Speaker 1: grabbed a you know, vacuum up some dust to study it?

546
00:25:09,000 --> 00:25:12,360
Speaker 2: We do actually have samples of space dust. It's super fascinating.

547
00:25:12,520 --> 00:25:14,639
Speaker 2: All the dust that we have sampled is only stuff

548
00:25:14,680 --> 00:25:18,360
Speaker 2: in our solar system, so we've never sampled stuff outside

549
00:25:18,359 --> 00:25:20,960
Speaker 2: of our solar system. The furthest probes we ever sent

550
00:25:21,000 --> 00:25:23,640
Speaker 2: have like just barely left the Solar system. But there's

551
00:25:23,640 --> 00:25:26,199
Speaker 2: plenty of space dust here in our solar system, and

552
00:25:26,440 --> 00:25:29,800
Speaker 2: many many satellites that we send have little dust collectors.

553
00:25:30,080 --> 00:25:32,160
Speaker 2: It's kind of a challenge because these satellites are moving

554
00:25:32,160 --> 00:25:34,919
Speaker 2: in very high speeds relative to the dust, so it

555
00:25:34,920 --> 00:25:37,359
Speaker 2: can be trickyed like catch the dust. But there are

556
00:25:37,359 --> 00:25:40,640
Speaker 2: some missions like the Star Dust Mission, specifically to capture

557
00:25:40,720 --> 00:25:42,760
Speaker 2: dust and bring it back, But then lots of other

558
00:25:42,800 --> 00:25:45,479
Speaker 2: satellites have like a little space dust collector on it.

559
00:25:45,560 --> 00:25:47,560
Speaker 2: We talked once about the JUNO mission that went to

560
00:25:47,640 --> 00:25:50,920
Speaker 2: Jupiter in twenty eleven had sort of an accidental star

561
00:25:51,040 --> 00:25:53,800
Speaker 2: dust collector on it. The dust was slamming into the

562
00:25:53,880 --> 00:25:56,560
Speaker 2: back of the solar panels on the satellite and then

563
00:25:56,640 --> 00:25:59,159
Speaker 2: spilating off little bits which you got picked up by

564
00:25:59,200 --> 00:26:01,600
Speaker 2: a camera, and it turned out to be like a

565
00:26:01,800 --> 00:26:04,880
Speaker 2: huge effective dust collector, and this is how we learned

566
00:26:04,920 --> 00:26:08,280
Speaker 2: that Mars is giving off all of this dust, which

567
00:26:08,320 --> 00:26:11,320
Speaker 2: is probably responsible for causing the zodiacal light. We have

568
00:26:11,400 --> 00:26:13,639
Speaker 2: also captured some dust and broad down to Earth and

569
00:26:13,680 --> 00:26:16,840
Speaker 2: studied it under a microscope and seeing like some fractions

570
00:26:16,840 --> 00:26:20,440
Speaker 2: of this stuff really are presolar grains, bits of dust

571
00:26:20,520 --> 00:26:24,119
Speaker 2: that are older than our solar system. Oh, super old dust,

572
00:26:24,400 --> 00:26:26,800
Speaker 2: super old dust. Our solar system is like four and

573
00:26:26,840 --> 00:26:29,560
Speaker 2: a half billion years old. But of course stars have

574
00:26:29,600 --> 00:26:31,840
Speaker 2: been around for much longer than that, and some of

575
00:26:31,880 --> 00:26:35,600
Speaker 2: them died and created these grains, which amazingly survived out

576
00:26:35,600 --> 00:26:38,800
Speaker 2: there in space and then formed into asteroids or formed

577
00:26:38,840 --> 00:26:41,480
Speaker 2: as part of the Earth, or still just floating out there.

578
00:26:41,600 --> 00:26:44,199
Speaker 2: It's incredible that some of these little grains have lasted

579
00:26:44,240 --> 00:26:44,640
Speaker 2: so long.

580
00:26:45,040 --> 00:26:47,240
Speaker 1: And we also know how much dust is out there

581
00:26:47,400 --> 00:26:51,479
Speaker 1: because it's polarized, right, It's got some sort of electrical charge,

582
00:26:51,640 --> 00:26:52,159
Speaker 1: noess to it.

583
00:26:52,320 --> 00:26:54,720
Speaker 2: Yeah, the dust grains are not spherical, right, They have

584
00:26:54,800 --> 00:26:57,560
Speaker 2: little shapes. They're irregular, which means that they tend to

585
00:26:57,560 --> 00:27:01,240
Speaker 2: be longer in one direction than another. And because they're

586
00:27:01,240 --> 00:27:04,320
Speaker 2: made of electromagnetic stuff, sometimes they have an overall charge.

587
00:27:04,680 --> 00:27:06,960
Speaker 2: You know. The dust like bumps against itself, it gets

588
00:27:07,000 --> 00:27:10,400
Speaker 2: like static electricity essentially, and then interstellar space it will

589
00:27:10,400 --> 00:27:13,000
Speaker 2: align with magnetic fields, you know, the Earth has a

590
00:27:13,000 --> 00:27:15,280
Speaker 2: magnetic field, the Sun has a magnetic field, the whole

591
00:27:15,280 --> 00:27:17,919
Speaker 2: galaxy has magnetic fields. We think there might even be

592
00:27:18,040 --> 00:27:22,120
Speaker 2: magnetic fields out there in between superclusters. We talked once

593
00:27:22,160 --> 00:27:25,720
Speaker 2: about primordial magnetic fields. Anyway, the dust grains are a

594
00:27:25,720 --> 00:27:29,040
Speaker 2: great way to measure those magnetic fields because they align

595
00:27:29,119 --> 00:27:32,480
Speaker 2: with the magnetic fields, and then when light passes through them,

596
00:27:32,800 --> 00:27:35,680
Speaker 2: it tends to polarize the light because the dust itself

597
00:27:35,720 --> 00:27:38,760
Speaker 2: is pointing in a specific direction. So light passing through

598
00:27:38,760 --> 00:27:41,000
Speaker 2: this region can tell you about the dust and about

599
00:27:41,000 --> 00:27:44,199
Speaker 2: the magnetic fields in that region. It's sort of an amazing

600
00:27:44,160 --> 00:27:46,560
Speaker 2: way to like learn about these huge regions of space

601
00:27:46,600 --> 00:27:47,879
Speaker 2: which otherwise look empty.

602
00:27:48,080 --> 00:27:51,320
Speaker 1: Well, it's like having special glasses to see the universe.

603
00:27:51,040 --> 00:27:54,240
Speaker 2: Yeah, exactly. So we have lots of ways to study

604
00:27:54,320 --> 00:27:56,800
Speaker 2: cosmic dust and to look at the spectrum. And you know,

605
00:27:56,840 --> 00:27:59,320
Speaker 2: looking at the spectrum also tells you what's in there,

606
00:27:59,400 --> 00:28:01,800
Speaker 2: because if it has like a certain crystal, then that

607
00:28:01,840 --> 00:28:05,600
Speaker 2: crystal has rotational and vibrational frequencies and they will absorb

608
00:28:05,600 --> 00:28:08,680
Speaker 2: with those frequencies or emitted those frequencies, and so they

609
00:28:08,680 --> 00:28:11,280
Speaker 2: can tell what's in cosmic dust. Even if we can't

610
00:28:11,280 --> 00:28:14,080
Speaker 2: sample it, like cosmic dust is far far away in

611
00:28:14,080 --> 00:28:16,520
Speaker 2: the milky Way. They can tell what it's made out

612
00:28:16,520 --> 00:28:19,200
Speaker 2: of based on how it glows and how it absorbs light.

613
00:28:19,480 --> 00:28:23,680
Speaker 1: Hmmm, because that can change, I guess, depending on what

614
00:28:23,720 --> 00:28:26,760
Speaker 1: was happening there that made the dust exactly.

615
00:28:26,400 --> 00:28:29,359
Speaker 2: Because cosmic dust is not static, right. One of the

616
00:28:29,359 --> 00:28:32,280
Speaker 2: big mysteries is like where's all this cosmic dust come from?

617
00:28:32,880 --> 00:28:34,639
Speaker 2: And you know, we think that a lot of it

618
00:28:34,680 --> 00:28:37,240
Speaker 2: is made in stars. It's made in supernova, It's made

619
00:28:37,280 --> 00:28:41,080
Speaker 2: in these stars called asymptotic giant branch stars. It's made

620
00:28:41,120 --> 00:28:44,480
Speaker 2: in super red giant stars to have like just the

621
00:28:44,560 --> 00:28:48,040
Speaker 2: right conditions in their atmosphere to coalesce this stuff, like

622
00:28:48,120 --> 00:28:51,640
Speaker 2: outflowing and cooling gases will create these grains and shoot

623
00:28:51,640 --> 00:28:54,160
Speaker 2: them out into the universe. And that's cool, but it

624
00:28:54,200 --> 00:28:56,920
Speaker 2: can't explain all the dust that we see out there.

625
00:28:57,080 --> 00:29:00,760
Speaker 2: There's like not enough stars and not enough for of

626
00:29:00,800 --> 00:29:03,240
Speaker 2: this dust to explain all the dust that's out there

627
00:29:03,280 --> 00:29:05,400
Speaker 2: in the universe. Because, as we said earlier, the dust

628
00:29:05,440 --> 00:29:09,320
Speaker 2: doesn't survive forever. Right. The dust is like shattered by supernova.

629
00:29:09,400 --> 00:29:11,640
Speaker 2: So we have like stars pumping dust out in the

630
00:29:11,720 --> 00:29:14,239
Speaker 2: universe supernova shattering it back in the gas, and that

631
00:29:14,320 --> 00:29:16,840
Speaker 2: leaves sort of a mystery because there's not enough being

632
00:29:16,880 --> 00:29:19,120
Speaker 2: made by the stars to explain all the stuff that

633
00:29:19,160 --> 00:29:20,960
Speaker 2: we see out there, all the dust in the Milky

634
00:29:20,960 --> 00:29:21,520
Speaker 2: Way I see.

635
00:29:21,560 --> 00:29:25,560
Speaker 1: So like dust is sort of like they're bigger molecules basically, right,

636
00:29:25,560 --> 00:29:28,840
Speaker 1: they're like little tiny pebbles, and inside of the stars

637
00:29:28,840 --> 00:29:31,360
Speaker 1: they just burn up I guess, right, because it's so

638
00:29:31,400 --> 00:29:32,920
Speaker 1: hot and under so much pressure.

639
00:29:33,080 --> 00:29:35,200
Speaker 2: Yeah, that's why they're made. Like in the outer atmosphere,

640
00:29:35,240 --> 00:29:39,040
Speaker 2: the outflowing and cooling gases coalesced into these grains. If

641
00:29:39,080 --> 00:29:41,320
Speaker 2: that ever happened inside the star, that would just burn

642
00:29:41,400 --> 00:29:41,960
Speaker 2: up as fuel.

643
00:29:42,040 --> 00:29:44,840
Speaker 1: Yeah, like the carbon and all the silicon. It's sort

644
00:29:44,880 --> 00:29:47,400
Speaker 1: of gassy within the sun, but once it gets out

645
00:29:47,480 --> 00:29:50,440
Speaker 1: of the Sun, it tends to form into molecules and

646
00:29:50,720 --> 00:29:53,120
Speaker 1: maybe little clumps mm hmm. But then you're saying like,

647
00:29:53,160 --> 00:29:55,840
Speaker 1: once it's out there in space, then if there's a supernova,

648
00:29:55,920 --> 00:29:59,440
Speaker 1: the supernova breaks it up back into carbon and silicon exactly.

649
00:29:59,480 --> 00:30:01,960
Speaker 2: So like the typical lifetime for a grain of dust,

650
00:30:02,160 --> 00:30:05,280
Speaker 2: it's like one hundred million years. It can float out there,

651
00:30:05,280 --> 00:30:07,960
Speaker 2: and then on average it's going to get shattered after

652
00:30:07,960 --> 00:30:10,640
Speaker 2: about one hundred million years, some longer, some shorter, but

653
00:30:10,760 --> 00:30:12,560
Speaker 2: on average one hundred million years.

654
00:30:12,360 --> 00:30:15,720
Speaker 1: There are that many supernovas happening that to shatter does

655
00:30:16,000 --> 00:30:16,640
Speaker 1: so frequently.

656
00:30:16,720 --> 00:30:19,280
Speaker 2: There are not that many supernovas, but they're frequent enough

657
00:30:19,520 --> 00:30:22,360
Speaker 2: and powerful enough to shatter this cosmic dust.

658
00:30:22,480 --> 00:30:25,080
Speaker 1: So like on average, for any point in space, you

659
00:30:25,240 --> 00:30:28,640
Speaker 1: experience this shattering supernova every hundred million years.

660
00:30:28,720 --> 00:30:31,520
Speaker 2: Yeah, the supernova are more common than every hundred million years.

661
00:30:31,560 --> 00:30:35,560
Speaker 2: There's a supernova in our galaxy roughly every fifty years,

662
00:30:35,680 --> 00:30:38,240
Speaker 2: so in one hundred million years, you're going to get

663
00:30:38,280 --> 00:30:42,320
Speaker 2: two million supernova across the galaxy and they're very very powerful.

664
00:30:42,600 --> 00:30:45,720
Speaker 2: So the modeling at least tells astronomers that these things

665
00:30:45,720 --> 00:30:48,760
Speaker 2: should be shattered on average within one hundred million years.

666
00:30:48,840 --> 00:30:50,680
Speaker 1: But the Earth has been around longer than that, and

667
00:30:50,840 --> 00:30:53,560
Speaker 1: have we experienced such as shattering supernova.

668
00:30:53,640 --> 00:30:55,400
Speaker 2: The Earth has been around much longer than that, but

669
00:30:55,400 --> 00:30:57,680
Speaker 2: it would take a very close by supernova to shatter

670
00:30:57,800 --> 00:31:00,600
Speaker 2: the Earth. These grains are more delicate than Earth, which

671
00:31:00,600 --> 00:31:02,480
Speaker 2: has been like compressed right.

672
00:31:02,520 --> 00:31:05,120
Speaker 1: M So like if there's a bit of dust circling

673
00:31:05,160 --> 00:31:07,240
Speaker 1: the Earth, it would get shattered by the supernova, but

674
00:31:07,320 --> 00:31:08,960
Speaker 1: not our atmosphere or US.

675
00:31:09,120 --> 00:31:11,400
Speaker 2: Yeah, dust is more fragile. You know, it's floating out

676
00:31:11,400 --> 00:31:13,920
Speaker 2: there into space. It's very low pressure. These things are

677
00:31:14,000 --> 00:31:16,800
Speaker 2: sort of fragile compared to like a rock on Earth.

678
00:31:16,920 --> 00:31:19,520
Speaker 1: All right, So then the mystery you're saying is like

679
00:31:19,560 --> 00:31:20,200
Speaker 1: how it's made?

680
00:31:20,280 --> 00:31:22,280
Speaker 2: Then, Yeah, the mystery is like why is there still

681
00:31:22,320 --> 00:31:24,760
Speaker 2: so much of it? There's a lot more cosmic dust

682
00:31:24,800 --> 00:31:27,560
Speaker 2: out there than can be explained by this combination of

683
00:31:27,560 --> 00:31:30,520
Speaker 2: stars producing it and then supernova's destroying it. There's a

684
00:31:30,560 --> 00:31:33,160
Speaker 2: lot more cosmic dust that can be explained by just

685
00:31:33,240 --> 00:31:33,880
Speaker 2: that process.

686
00:31:34,080 --> 00:31:36,080
Speaker 1: Maybe the unergy just hasn't bought that neat device you

687
00:31:36,120 --> 00:31:37,240
Speaker 1: have to get rid of dust.

688
00:31:40,880 --> 00:31:43,440
Speaker 2: Well, one theory about what's going on is that cosmic

689
00:31:43,520 --> 00:31:47,600
Speaker 2: dust itself can reform out there between the stars. So

690
00:31:47,640 --> 00:31:50,280
Speaker 2: you take these little pebbles, these little grains, you send

691
00:31:50,280 --> 00:31:53,560
Speaker 2: them out there. They get shattered back into gas, but

692
00:31:53,600 --> 00:31:55,720
Speaker 2: there's like a tiny little seed left, you know, a

693
00:31:55,760 --> 00:31:59,200
Speaker 2: few molecules still cleaning together, and then those can accrete

694
00:31:59,360 --> 00:32:02,440
Speaker 2: because they're flowing through these molecular clouds which are super

695
00:32:02,520 --> 00:32:06,200
Speaker 2: duper cold, and basically because you have a few tiny,

696
00:32:06,200 --> 00:32:08,800
Speaker 2: little grains left, they can like pick up more like

697
00:32:08,880 --> 00:32:11,440
Speaker 2: ice can form on these things, and you get these

698
00:32:11,560 --> 00:32:15,880
Speaker 2: layers that surround the original tiny core that rebuilds this

699
00:32:15,960 --> 00:32:17,960
Speaker 2: thing back up into what you would call dust.

700
00:32:18,160 --> 00:32:21,760
Speaker 1: I see. Yeah, just reforms because and also because of gravity.

701
00:32:21,800 --> 00:32:24,160
Speaker 1: I imagine, right, like even if you split a little

702
00:32:24,200 --> 00:32:27,200
Speaker 1: grain of dust out there, eventually, gravity is going to

703
00:32:27,240 --> 00:32:28,479
Speaker 1: put it back together, isn't it.

704
00:32:28,560 --> 00:32:31,280
Speaker 2: Yeah, exactly? And you know that's the process that eventually

705
00:32:31,400 --> 00:32:36,120
Speaker 2: forms stars and planets, right, These little gravitational seeds gathered

706
00:32:36,160 --> 00:32:40,200
Speaker 2: together over very long periods, but it begins with gathering

707
00:32:40,280 --> 00:32:43,720
Speaker 2: little bits of ice here and there and reforming. And

708
00:32:43,800 --> 00:32:46,120
Speaker 2: so some of the cognic dust that's out there are

709
00:32:46,160 --> 00:32:49,120
Speaker 2: like og grains that came from their stars and haven't

710
00:32:49,160 --> 00:32:51,880
Speaker 2: been shattered, but most of it probably comes from this

711
00:32:52,000 --> 00:32:55,240
Speaker 2: process where they have been shattered and then they coalesce,

712
00:32:55,600 --> 00:32:58,120
Speaker 2: collecting ice and reforming into grains.

713
00:32:58,360 --> 00:33:00,800
Speaker 1: All right, Well, you mentioned that there are some things

714
00:33:00,840 --> 00:33:04,760
Speaker 1: called dust destroyers out there in space and also mysterious

715
00:33:04,760 --> 00:33:07,760
Speaker 1: ways that dust is made, and so let's dig deeper

716
00:33:07,800 --> 00:33:23,560
Speaker 1: into those things. But first let's take a quick break. Okay,

717
00:33:23,560 --> 00:33:26,040
Speaker 1: we're talking about dust and Daniels you're saying, the big

718
00:33:26,120 --> 00:33:28,440
Speaker 1: question is where does it come from? Because most of

719
00:33:28,480 --> 00:33:30,520
Speaker 1: the dust. If you just put dust out there in space,

720
00:33:30,600 --> 00:33:34,960
Speaker 1: within one hundred million years, some distant supernova's shockwave is

721
00:33:35,040 --> 00:33:39,440
Speaker 1: gonna shatter that back into its constituent atoms like carbon

722
00:33:39,480 --> 00:33:42,440
Speaker 1: and slogan. It doesn't seem that fragile here on Earth, right,

723
00:33:42,480 --> 00:33:44,640
Speaker 1: Like if I blow on dust, it doesn't break up

724
00:33:44,680 --> 00:33:45,800
Speaker 1: into carbon gas.

725
00:33:46,080 --> 00:33:47,760
Speaker 2: I mean, you're pretty tough, dude, But are you saying

726
00:33:47,760 --> 00:33:49,800
Speaker 2: that your breath is as powerful as a supernova?

727
00:33:50,000 --> 00:33:55,080
Speaker 1: Well, some mornings, yeah, But I mean, like it's weird

728
00:33:55,120 --> 00:33:57,840
Speaker 1: to think that it's so powerful because here on Earth

729
00:33:57,880 --> 00:34:00,000
Speaker 1: we don't feel these supernovas. But you're saying it's drying

730
00:34:00,080 --> 00:34:02,120
Speaker 1: enough to like split apart molecules in space.

731
00:34:02,240 --> 00:34:05,080
Speaker 2: The dust is more fragile than the Earth is. Yeah,

732
00:34:05,160 --> 00:34:08,040
Speaker 2: and it hasn't been a supernova in our Milky Way

733
00:34:08,160 --> 00:34:10,120
Speaker 2: in quite a few hundred years, so it's not like

734
00:34:10,160 --> 00:34:12,799
Speaker 2: we're feeling these things every ten years or so. Even

735
00:34:12,800 --> 00:34:15,680
Speaker 2: these supernovas are not that common. But yeah, the lifetime

736
00:34:15,719 --> 00:34:19,160
Speaker 2: of dust is shorter than the lifetime of the Earth.

737
00:34:19,280 --> 00:34:21,880
Speaker 2: So the Earth and planets and stars definitely survived these

738
00:34:21,880 --> 00:34:25,200
Speaker 2: super nova shock waves in ways that the stellar dust doesn't.

739
00:34:25,320 --> 00:34:27,799
Speaker 1: So then the mystery is, like, if it is being

740
00:34:27,840 --> 00:34:30,440
Speaker 1: destroyed out there in space, why is there still dust?

741
00:34:30,719 --> 00:34:35,360
Speaker 1: Why is in and auges gas and individual atoms exactly?

742
00:34:35,400 --> 00:34:37,440
Speaker 2: And it's important that the dust is there because the

743
00:34:37,520 --> 00:34:41,600
Speaker 2: dust seeds planetary formation and star formation, you know, in

744
00:34:41,600 --> 00:34:44,759
Speaker 2: ways that we didn't always understand. Like back in the seventies,

745
00:34:44,800 --> 00:34:47,879
Speaker 2: before we really understood cosmic dust at all, people thought

746
00:34:47,880 --> 00:34:51,120
Speaker 2: that our solar system started just from gas, that you

747
00:34:51,120 --> 00:34:53,200
Speaker 2: could start from just like a blob of hydrogen and

748
00:34:53,239 --> 00:34:56,480
Speaker 2: helium and form all of this stuff, which doesn't really

749
00:34:56,520 --> 00:34:58,320
Speaker 2: make sense to me because then like where you're getting

750
00:34:58,320 --> 00:35:00,880
Speaker 2: all the iron and all this stuff to make planets.

751
00:35:00,960 --> 00:35:03,480
Speaker 2: But now it's very well understood that most of the

752
00:35:03,520 --> 00:35:05,880
Speaker 2: iron and most of the heavy metals are bound up

753
00:35:05,880 --> 00:35:08,440
Speaker 2: in these cosmic dust grains and you need them to

754
00:35:08,520 --> 00:35:12,720
Speaker 2: form solar systems with interesting bits on them like rocks

755
00:35:12,760 --> 00:35:13,280
Speaker 2: and people.

756
00:35:14,120 --> 00:35:17,160
Speaker 1: So then are you saying that like just gravity, you know,

757
00:35:17,280 --> 00:35:19,320
Speaker 1: pulling all of this stuff out there floating in space

758
00:35:19,360 --> 00:35:21,680
Speaker 1: into dust is not enough to account for the dust

759
00:35:21,680 --> 00:35:23,279
Speaker 1: we're seeing, Well, why not?

760
00:35:23,640 --> 00:35:26,680
Speaker 2: So just stellar production of dust isn't enough to account

761
00:35:26,680 --> 00:35:28,640
Speaker 2: for the dust that we're seeing. You need some way

762
00:35:28,680 --> 00:35:32,120
Speaker 2: to reform dust in the interstellar medium, otherwise, as you say,

763
00:35:32,160 --> 00:35:34,120
Speaker 2: it would be just gas. But we think that these

764
00:35:34,160 --> 00:35:37,440
Speaker 2: little grains probably do gather back together from gravity and

765
00:35:37,440 --> 00:35:40,480
Speaker 2: from deecretion of ice crystals. As you pass through a

766
00:35:40,480 --> 00:35:43,279
Speaker 2: molecular cloud, there's going to be chemical bonds that form

767
00:35:43,520 --> 00:35:46,399
Speaker 2: because these things are a little sticky, right, And so

768
00:35:46,600 --> 00:35:49,839
Speaker 2: that is a process that they think might explain where

769
00:35:49,880 --> 00:35:52,239
Speaker 2: the gas comes from. I talked to one scientist at

770
00:35:52,239 --> 00:35:55,560
Speaker 2: the University of Wasita in Japan who's super interested in

771
00:35:55,640 --> 00:35:58,600
Speaker 2: cosmic dust, and she said that this is like the

772
00:35:58,719 --> 00:36:02,120
Speaker 2: leading theory for how cosmic dust is being regenerated. But

773
00:36:02,160 --> 00:36:04,759
Speaker 2: nobody's like demonstrated this in the lab. They haven't done

774
00:36:05,000 --> 00:36:07,520
Speaker 2: tests where they take like a little grain and pass

775
00:36:07,560 --> 00:36:10,400
Speaker 2: it through a dust cloud and see this stuff reform.

776
00:36:10,480 --> 00:36:13,160
Speaker 2: It's alsort of like theoretical chemistry at this point.

777
00:36:13,280 --> 00:36:15,920
Speaker 1: Well, you need to replicate zero gravity, wouldn't you.

778
00:36:16,000 --> 00:36:18,239
Speaker 2: Yeah, exactly. It's the kind of experiment you'd want to

779
00:36:18,239 --> 00:36:20,680
Speaker 2: do out in space or on the iss or something.

780
00:36:20,920 --> 00:36:23,160
Speaker 1: So then that's the best answer to this mystery.

781
00:36:23,280 --> 00:36:24,800
Speaker 2: That's the best answer to this mystery.

782
00:36:24,920 --> 00:36:26,720
Speaker 1: So it sounds like you're saying, like there's a giant

783
00:36:26,800 --> 00:36:29,280
Speaker 1: vacuum in space just gathering all this stuff dust.

784
00:36:31,040 --> 00:36:33,000
Speaker 2: Well, you know again it's the supernova, right, Those are

785
00:36:33,000 --> 00:36:36,239
Speaker 2: the dust stories shattering it back into gas, and then

786
00:36:36,280 --> 00:36:39,280
Speaker 2: they think that it's probably reforming. But another really fascinating

787
00:36:39,280 --> 00:36:41,480
Speaker 2: way that they're trying to understand this process is by

788
00:36:41,480 --> 00:36:44,440
Speaker 2: trying to answer a related question, which is like how

789
00:36:44,520 --> 00:36:47,920
Speaker 2: early did dust form in the universe. So now that

790
00:36:47,920 --> 00:36:51,160
Speaker 2: we have like a super powerful infrared telescope, we can

791
00:36:51,200 --> 00:36:54,399
Speaker 2: look deeper into the history of the universe and look

792
00:36:54,480 --> 00:36:57,719
Speaker 2: for evidence of dust very very early on, like what

793
00:36:57,880 --> 00:37:00,560
Speaker 2: is the oldest dust that we can see in the universe,

794
00:37:00,640 --> 00:37:03,760
Speaker 2: and they'll give us a sense for these processes because remember,

795
00:37:03,800 --> 00:37:06,640
Speaker 2: like stars didn't turn on for a few hundred million years,

796
00:37:06,920 --> 00:37:08,839
Speaker 2: so the origin of the dust can really tell us

797
00:37:08,840 --> 00:37:10,640
Speaker 2: about like who is making this dust?

798
00:37:10,880 --> 00:37:12,840
Speaker 1: Right I think I mean, like if you look out

799
00:37:12,880 --> 00:37:16,000
Speaker 1: into deep space with your telescopes, you're looking back in time,

800
00:37:16,440 --> 00:37:19,600
Speaker 1: so like the light you're getting from those deep places

801
00:37:19,600 --> 00:37:22,279
Speaker 1: in the universe is really old light, which might be

802
00:37:22,480 --> 00:37:23,760
Speaker 1: old dust exactly.

803
00:37:24,280 --> 00:37:26,640
Speaker 2: And we think that most of the dust out there

804
00:37:26,640 --> 00:37:28,799
Speaker 2: in the universe right now is probably produced by these

805
00:37:28,840 --> 00:37:32,760
Speaker 2: super red giant stars and this asymptotic giant branch stars.

806
00:37:32,920 --> 00:37:34,759
Speaker 2: These special stars are super big and have just the

807
00:37:34,800 --> 00:37:37,960
Speaker 2: right conditions for this, like outflowing gas to cool and

808
00:37:38,000 --> 00:37:40,760
Speaker 2: form these little blobs which then flow down into space.

809
00:37:40,960 --> 00:37:44,400
Speaker 2: But the James Web Space Telescope recently saw direct evidence

810
00:37:44,520 --> 00:37:48,480
Speaker 2: for really really old grains of stars, like several hundred

811
00:37:48,560 --> 00:37:51,120
Speaker 2: million years or up to a billion years after the

812
00:37:51,200 --> 00:37:54,480
Speaker 2: Big Bang, too long ago for these stars, Like, we

813
00:37:54,560 --> 00:37:57,760
Speaker 2: don't think that there were these super red giant stars

814
00:37:57,800 --> 00:38:01,600
Speaker 2: early on in the universe. So probably the first dust

815
00:38:01,680 --> 00:38:04,279
Speaker 2: made in the universe were made by supernova from the

816
00:38:04,320 --> 00:38:05,960
Speaker 2: first generation of stars.

817
00:38:06,320 --> 00:38:09,399
Speaker 1: WHOA wait, so how do we know we're looking at

818
00:38:10,200 --> 00:38:11,400
Speaker 1: dust that old.

819
00:38:11,200 --> 00:38:13,560
Speaker 2: Because we're looking at images of galaxies that are super

820
00:38:13,600 --> 00:38:16,080
Speaker 2: duper far away. And so you can look at a

821
00:38:16,080 --> 00:38:18,839
Speaker 2: galaxy and you can understand from its red shift how

822
00:38:18,840 --> 00:38:21,080
Speaker 2: fast it's moving away from us, and therefore how far

823
00:38:21,120 --> 00:38:23,680
Speaker 2: away it is, and therefore the age of the thing

824
00:38:23,719 --> 00:38:24,439
Speaker 2: we're looking at.

825
00:38:24,640 --> 00:38:26,560
Speaker 1: Isn't most of that light coming from the stars in

826
00:38:26,640 --> 00:38:27,240
Speaker 1: the galaxy.

827
00:38:27,360 --> 00:38:29,320
Speaker 2: Yeah, most of that light does come from the stars,

828
00:38:29,520 --> 00:38:31,920
Speaker 2: But we're looking at an infrared telescope, and stars are

829
00:38:32,000 --> 00:38:35,319
Speaker 2: much quieter in the infrared, so we're seeing information from

830
00:38:35,360 --> 00:38:36,200
Speaker 2: the dust also.

831
00:38:36,600 --> 00:38:38,640
Speaker 1: Oh, I see, like we see the galaxy with a

832
00:38:38,920 --> 00:38:42,200
Speaker 1: regular light and then we switch the filter over to infrared,

833
00:38:42,280 --> 00:38:45,520
Speaker 1: and then you're basically getting the light from the dust.

834
00:38:45,320 --> 00:38:48,359
Speaker 2: Exactly, and specifically, what they're seeing here is extinction, right.

835
00:38:48,360 --> 00:38:51,920
Speaker 2: They're seeing an absorption feature at a very specific wavelength

836
00:38:52,040 --> 00:38:55,000
Speaker 2: twenty one seventy five inkstrums that they think is like

837
00:38:55,040 --> 00:38:58,560
Speaker 2: a dust wavelength, that that's what dust absorbs. So they

838
00:38:58,600 --> 00:39:00,760
Speaker 2: see like a dip in the light in this galaxy

839
00:39:00,880 --> 00:39:03,080
Speaker 2: at just the right wavelength that tells them that there

840
00:39:03,160 --> 00:39:05,920
Speaker 2: is dust in this very very old galaxy.

841
00:39:06,520 --> 00:39:11,000
Speaker 1: Oh, because I guess the size of your thing affects

842
00:39:11,080 --> 00:39:13,319
Speaker 1: what kind of light you're absorbing, right, because you kind

843
00:39:13,360 --> 00:39:15,920
Speaker 1: of have to be at about the same size as

844
00:39:15,920 --> 00:39:17,520
Speaker 1: the wavelength to absorb it exactly.

845
00:39:17,560 --> 00:39:21,279
Speaker 2: Earlier we were talking about how dust absorbs as various frequencies.

846
00:39:21,360 --> 00:39:23,480
Speaker 2: In general, the picture is that it interacts more with

847
00:39:23,560 --> 00:39:25,960
Speaker 2: blue light. It reflects that blue light, and it doesn't

848
00:39:25,960 --> 00:39:28,920
Speaker 2: interact as much with redor light because, as you say,

849
00:39:28,960 --> 00:39:31,960
Speaker 2: it's too small, like the wavelength of light is bigger

850
00:39:31,960 --> 00:39:34,680
Speaker 2: than these dust grains so it doesn't interact with them.

851
00:39:35,200 --> 00:39:39,000
Speaker 2: But also these things contain specific chemicals and sometimes little crystals,

852
00:39:39,040 --> 00:39:42,719
Speaker 2: and those have features that absorb at certain wavelengths, like

853
00:39:42,800 --> 00:39:46,799
Speaker 2: little oscillations and vibrational energy levels of these little crystals

854
00:39:46,840 --> 00:39:50,600
Speaker 2: inside these dust grains will absorb at specific wavelengths that

855
00:39:50,680 --> 00:39:53,520
Speaker 2: are known to be dust wavelengths. So they saw this

856
00:39:53,640 --> 00:39:56,279
Speaker 2: in this signature from the James Web Space telescope from

857
00:39:56,280 --> 00:39:59,919
Speaker 2: the duper Ancient galaxy, a galaxy too old to whole

858
00:40:00,080 --> 00:40:03,600
Speaker 2: any of these red giant stars or ASB stars. So

859
00:40:03,640 --> 00:40:07,080
Speaker 2: they think probably this is ancient dust, maybe from the

860
00:40:07,120 --> 00:40:11,040
Speaker 2: first round of generation of dust in the universe, probably

861
00:40:11,080 --> 00:40:13,120
Speaker 2: from supernova.

862
00:40:12,320 --> 00:40:15,040
Speaker 1: Like the first supernova's right, because that's that's when the

863
00:40:15,400 --> 00:40:16,799
Speaker 1: heavier elements are made.

864
00:40:16,920 --> 00:40:19,520
Speaker 2: And it's fascinating because supernova make this stuff and then

865
00:40:19,560 --> 00:40:22,080
Speaker 2: also destroy it, so they kind of like clean up

866
00:40:22,120 --> 00:40:22,880
Speaker 2: after themselves.

867
00:40:23,000 --> 00:40:25,000
Speaker 1: Right, Wait, how can it make them and destroy them

868
00:40:25,040 --> 00:40:25,640
Speaker 1: at the same time.

869
00:40:25,719 --> 00:40:27,799
Speaker 2: These dust grains are made by supernovas sort of in

870
00:40:27,840 --> 00:40:30,719
Speaker 2: the last dying minutes of a star's life, where you know,

871
00:40:30,760 --> 00:40:34,239
Speaker 2: these shockwaves create really intense environments and specific isotopes, and

872
00:40:34,280 --> 00:40:36,759
Speaker 2: then the outflow and the cooling makes these grains, but

873
00:40:36,800 --> 00:40:40,799
Speaker 2: then shockwaves from supernova's also destroy dust. Right, supernova are

874
00:40:40,840 --> 00:40:44,200
Speaker 2: the dust destroyers of the universe, So they both create

875
00:40:44,239 --> 00:40:46,480
Speaker 2: it and they also are responsible for destroying it.

876
00:40:46,640 --> 00:40:48,520
Speaker 1: Which do they do first? Do they first clean up

877
00:40:48,520 --> 00:40:50,200
Speaker 1: and then put a bunch of dust there or do

878
00:40:50,280 --> 00:40:52,600
Speaker 1: they put a bunch of dust and then immediately destroy it.

879
00:40:52,680 --> 00:40:54,520
Speaker 1: Can't be the latter, can it, because then we wouldn't

880
00:40:54,520 --> 00:40:55,040
Speaker 1: have any dust.

881
00:40:55,120 --> 00:40:57,560
Speaker 2: It must be that the shockwave from the supernova travels

882
00:40:57,560 --> 00:40:59,960
Speaker 2: out faster than dust grains, which means the first they're

883
00:41:00,080 --> 00:41:02,160
Speaker 2: cleaning up and then they're making a mess. So I

884
00:41:02,160 --> 00:41:04,840
Speaker 2: guess you're right. Actually it's in the wrong order. Or

885
00:41:04,920 --> 00:41:08,239
Speaker 2: they're destroying the dust grains from other supernovas and to

886
00:41:08,360 --> 00:41:09,719
Speaker 2: make space for their own.

887
00:41:10,760 --> 00:41:14,400
Speaker 1: So they're not cleaning up after themselves. They're just cleaning

888
00:41:14,440 --> 00:41:15,839
Speaker 1: it so that they can make a mess.

889
00:41:15,920 --> 00:41:18,080
Speaker 2: Yeah, they're sort of like scrubbing the graffiti off the

890
00:41:18,120 --> 00:41:19,880
Speaker 2: wall and then writing their own name on it.

891
00:41:20,080 --> 00:41:22,960
Speaker 1: Yeah.

892
00:41:23,040 --> 00:41:25,279
Speaker 2: I take it back. I take back everything positive I

893
00:41:25,320 --> 00:41:26,520
Speaker 2: said about supernovas well.

894
00:41:26,520 --> 00:41:29,800
Speaker 1: They're the reason we're here, so glad they haven't wiped

895
00:41:30,080 --> 00:41:34,359
Speaker 1: us off. I guess I'm we're glad that they made us.

896
00:41:34,440 --> 00:41:37,120
Speaker 1: All right, Well, what does it all mean about our

897
00:41:37,280 --> 00:41:39,000
Speaker 1: understanding of the history of the universe.

898
00:41:39,000 --> 00:41:41,960
Speaker 2: It means that all these processes, the ones that form stars,

899
00:41:42,000 --> 00:41:44,759
Speaker 2: that lead to supernovas, that lead to dust creation and

900
00:41:44,840 --> 00:41:48,640
Speaker 2: dust destruction, it's all part of this huge cosmic dance.

901
00:41:49,040 --> 00:41:50,920
Speaker 2: You know. We tend to think of the Milky Way

902
00:41:50,960 --> 00:41:53,640
Speaker 2: as like done, We've made all these stars. They're just

903
00:41:53,680 --> 00:41:55,960
Speaker 2: sort of like hanging out and burning now. But it's

904
00:41:56,000 --> 00:41:58,520
Speaker 2: a process, you know, and everything is connected as like

905
00:41:58,640 --> 00:42:01,640
Speaker 2: dust flowing and swirling. These things are being created, they're

906
00:42:01,640 --> 00:42:05,800
Speaker 2: being destroyed, they're being reformed. The whole thing is a big, frothing, active,

907
00:42:06,040 --> 00:42:08,920
Speaker 2: lively mess of processes, all of which are important to

908
00:42:09,040 --> 00:42:10,680
Speaker 2: creating the universe as we know it.

909
00:42:10,800 --> 00:42:13,480
Speaker 1: Yeah, and it sounds kind of precarious, right, Like basically,

910
00:42:13,600 --> 00:42:16,319
Speaker 1: we need a supernova to make all this dust, and

911
00:42:16,360 --> 00:42:19,719
Speaker 1: we need the dust to basically clump together into planets

912
00:42:19,719 --> 00:42:23,520
Speaker 1: and stars quickly before the next supernova tries to wipe

913
00:42:23,600 --> 00:42:27,759
Speaker 1: the board clean. Right, Like if another supernova had gone

914
00:42:27,800 --> 00:42:30,799
Speaker 1: off near us, or not even neros, but around us,

915
00:42:31,440 --> 00:42:35,120
Speaker 1: before the Sun, you know, got put together and the

916
00:42:35,160 --> 00:42:37,480
Speaker 1: Earth got put together, we might not be here. Is

917
00:42:37,520 --> 00:42:37,879
Speaker 1: that true?

918
00:42:37,920 --> 00:42:40,160
Speaker 2: It definitely would have affected things, but it's not something

919
00:42:40,160 --> 00:42:42,759
Speaker 2: we understand very well. And supernova's contribute in lots of

920
00:42:42,760 --> 00:42:45,760
Speaker 2: different ways. Like first of all, they destroy these grains,

921
00:42:46,040 --> 00:42:49,759
Speaker 2: but then later on a supernova shockwave can actually precipitate

922
00:42:49,800 --> 00:42:54,280
Speaker 2: the gravitational collapse of surviving grains into a new star.

923
00:42:54,880 --> 00:42:57,960
Speaker 2: So supernova shockwaves play lots of different complex roles. And

924
00:42:58,000 --> 00:43:00,680
Speaker 2: to say like that we even understand this story would

925
00:43:00,719 --> 00:43:02,719
Speaker 2: be to overstate it. For sure, there's a lot of

926
00:43:02,760 --> 00:43:05,000
Speaker 2: parts of this that we still don't understand. What we

927
00:43:05,040 --> 00:43:07,920
Speaker 2: do know is that it's complicated and everything is connected.

928
00:43:08,239 --> 00:43:10,760
Speaker 1: Sounds like our knowledge of it is a little dusty.

929
00:43:12,200 --> 00:43:14,440
Speaker 2: There's definitely a lot of ancient wisdom out there we

930
00:43:14,480 --> 00:43:16,720
Speaker 2: haven't yet collected, and we can look forward to blowing

931
00:43:16,719 --> 00:43:18,400
Speaker 2: the dust off of all of these.

932
00:43:18,239 --> 00:43:20,920
Speaker 1: Secrets, but not too hard, because then you might destroy

933
00:43:20,960 --> 00:43:21,799
Speaker 1: the dust.

934
00:43:21,640 --> 00:43:24,000
Speaker 2: Right, only if you have supernova morning breath.

935
00:43:24,320 --> 00:43:26,319
Speaker 1: All right, I guess the next time you look at

936
00:43:26,400 --> 00:43:28,239
Speaker 1: into the nice guy, I know that you're looking at

937
00:43:28,239 --> 00:43:30,560
Speaker 1: a bunch of dust as well, not just the beautiful

938
00:43:30,600 --> 00:43:31,440
Speaker 1: twinkling stars.

939
00:43:31,640 --> 00:43:35,200
Speaker 2: These tiny but mighty grains play an important role in

940
00:43:35,239 --> 00:43:38,160
Speaker 2: the formation of the Solar system, in helping us understand

941
00:43:38,200 --> 00:43:41,160
Speaker 2: what's out there, and also in blocking our view of

942
00:43:41,320 --> 00:43:43,000
Speaker 2: part of the glorious cosmos.

943
00:43:43,280 --> 00:43:45,759
Speaker 1: Hope you enjoyed that. Thanks for joining us. See you

944
00:43:45,760 --> 00:43:48,920
Speaker 1: next time. Hey, it's hoar Hey from the podcast, and

945
00:43:48,960 --> 00:43:51,920
Speaker 1: I'm super excited to announce that my new book, Oliver's

946
00:43:52,000 --> 00:43:56,040
Speaker 1: Great Big Universe, is available to order now.

947
00:44:02,840 --> 00:44:05,640
Speaker 2: Thanks for listening, and remember that Daniel and Jorge Explain

948
00:44:05,680 --> 00:44:09,680
Speaker 2: the Universe is a production of iHeartRadio. For more podcasts

949
00:44:09,680 --> 00:44:14,360
Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

950
00:44:14,440 --> 00:44:16,160
Speaker 2: you listen to your favorite shows.