Speaker 1: Hey, Daniel, you're kind of a neat freak, aren't you.
Speaker 2: I do like to keep my laptop nicely, well dusted.
Speaker 1: The weight dust it like you put dust in it,
Speaker 1: or you take out dust, or you wipe dust out
Speaker 1: of it.
Speaker 2: Good question. I mean, I like my cookies well dusted
Speaker 2: with sugar, but my laptop keyboard well dusted with zero dust.
Speaker 1: Yeah, household dust is less delicious, and powdered sugar is
Speaker 1: in regular dust, like fifty percent skin cells.
Speaker 2: That sounds like a pretty gross thing to put on
Speaker 2: your cookies. On the other hand, it would be pretty
Speaker 2: weird if powdered sugar just like accumulated in your.
Speaker 1: House, it'd be pretty sweet.
Speaker 2: We might call for some sweeping changes.
Speaker 1: Uh, I'm glad you got to dust off that old punt.
Speaker 2: Hi.
Speaker 1: I'm Poor hammy cartoonas and the author of Oliver's Great
Speaker 1: Big Universe.
Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor
Speaker 2: at UC Irvine, and I don't like dust as much
Speaker 2: as astronomers do.
Speaker 1: But do you still like it a little bit?
Speaker 2: I like dust the way I like the sun. It's fascinating,
Speaker 2: it's interesting, it's useful, It tells us about the cosmos.
Speaker 2: But I don't really want it on my laptop or
Speaker 2: on my table.
Speaker 1: But everywhere else it's okay.
Speaker 2: Yeah, study it from a distance, you know, the way
Speaker 2: like I'm fascinated by cheetahs, but I don't really want
Speaker 2: to have a cheat on my lap.
Speaker 1: Do you carry a duster with you at all times?
Speaker 3: Then?
Speaker 2: I actually do have this very fancy little machine for
Speaker 2: removing dust from your keyboard.
Speaker 1: Is it called blowing on it? Or did you Did
Speaker 1: you actually pay for a machine to do that?
Speaker 2: I actually have a nice little machine. It's really quite good. Yeah,
Speaker 2: I should call it mini made.
Speaker 1: Wait, what is it like a vacuum?
Speaker 2: No, it's like a little blower, you know. It replaces
Speaker 2: those disposable cans that I thought were not very environmentally friendly,
Speaker 2: though I do love them.
Speaker 3: Mmm.
Speaker 1: Oh, I see you mean like the dust between the keys,
Speaker 1: like you want to get rid of it, like in
Speaker 1: the nooks and crannies.
Speaker 2: Yeah, exactly. I like a nice clean keyboard.
Speaker 3: Oh.
Speaker 1: I thought you meant like on your screen, because I
Speaker 1: think you can just wipe that off.
Speaker 2: I think you can. But probably that dust contains all
Speaker 2: sorts of fascinating stories where each of those bits has
Speaker 2: been But you.
Speaker 1: Know, if you just blow the dust, it's just getting
Speaker 1: in the air and then it's going to come back
Speaker 1: down on your keyboard.
Speaker 2: I know it's a cycle. Unless I'm willing to live
Speaker 2: in a clean room, I can never escape it.
Speaker 1: So you don't like living in clean rooms.
Speaker 2: I don't have to wear a hairnet and booties all
Speaker 2: the time.
Speaker 1: No, just some of the time. But anyways, welcome for
Speaker 1: a podcast Daniel and Jorge Explain the Universe, a production
Speaker 1: of our Heart Radio.
Speaker 2: In which we dive deep into the cycles of the universe,
Speaker 2: the ones that produce massive stars and tiny grains of dust.
Speaker 2: Everything out there in the universe has a history and
Speaker 2: tells a story, and if we can unpack it, unravel
Speaker 2: it and study it, you can reveal those stories and
Speaker 2: the history of our own cosmos. To learn about the
Speaker 2: formation of the planets and stars and the universe itself,
Speaker 2: from the biggest clues to the tiniest speck of dust.
Speaker 1: That's right, we blow the dust off of the universe,
Speaker 1: trying to uncover what's underneath, What shiny surface or interesting
Speaker 1: facts are there for us to understand and to learn about.
Speaker 2: I love in archaeology, how every time they're going to
Speaker 2: discover something amazing, they always have to blow dust off
Speaker 2: of it, pull cobwebs off of it. That's like your
Speaker 2: visual cue that you're about to learn something ancient.
Speaker 1: Wait, wait, what do you mean?
Speaker 2: I mean? I just watched a new Indian Jones. I guess.
Speaker 2: So you know anytime they unde earth something from the
Speaker 2: olden days, it's always covered in dust.
Speaker 1: Of course, mm to see they carry a dust with
Speaker 1: them at all times. Maybe you can buy one of
Speaker 1: those devices and you didn't have to waste electricity.
Speaker 2: I'd be that neat freak archaeologist. I don't think i'd
Speaker 2: get very far in the field.
Speaker 1: Yeah, it is a dusty universe full of amazing things,
Speaker 1: where even the dust is interesting. In the universe.
Speaker 2: Down here on Earth we see dust is sort of
Speaker 2: a nuisance, something to brush out of our But out
Speaker 2: in space dust plays a very important role in the
Speaker 2: formation of stars and planets, and it can reveal that history.
Speaker 2: Dust is not just a nuisance. It's a fascinating pile
Speaker 2: of tiny clues.
Speaker 1: So today end podcast, we'll be asking the question how
Speaker 1: important is cosmic dust? Now? Hopefully this episode won't be
Speaker 1: a bust.
Speaker 2: Should we just be sweeping cosmic dust under the cosmic
Speaker 2: rug or should we take it seriously and study it
Speaker 2: in detail.
Speaker 1: That's a bit of a dusty pun there, you used
Speaker 1: it already, But yeah, it's an interesting question here cosmic dust.
Speaker 1: I guess it's different than regular dust.
Speaker 2: Well, I think there's fewer dead skin cells and leftover
Speaker 2: bits of insects out there floating between the stars than
Speaker 2: there is here on Earth. But cosmic dust also falls
Speaker 2: to Earth.
Speaker 1: You mean it gets sprinkled from space like powdered sugar.
Speaker 2: Well, you know that space isn't empty, and there's dust
Speaker 2: out there between the stars but also between the planets,
Speaker 2: and as the Earth moves through these cosmic dust clouds,
Speaker 2: it accumulates some of them. Some tons of dust fall
Speaker 2: to Earth every year from interplanetary space out there in
Speaker 2: the Solar System.
Speaker 1: WHOA is it like dandruff space? Dandruff? Or is that
Speaker 1: too embarrassing?
Speaker 2: We had a whole fun episode about where this stuff
Speaker 2: comes from. It's a bit of a mystery. There's a
Speaker 2: recent experiment though, that tries to pin the blame on Mars.
Speaker 2: It might be that dust storms on Mars are blowing
Speaker 2: that stuff out into space and the Earth is flying
Speaker 2: through Mars's dust clouds. So yeah, I guess it's all
Speaker 2: Martian dandruff.
Speaker 1: Yeah, Mars needs some head and shoulders.
Speaker 2: Well first they need heads and shoulders. That'd be pretty
Speaker 2: awesome discovery.
Speaker 1: Yeah, or maybe just a hat that might help. But
Speaker 1: it is an interesting question. How important is cosmic dust?
Speaker 1: Which I guess means Daniel, that cosmic dust is important.
Speaker 2: Cosmic dust is more important than you might think. I mean,
Speaker 2: the word dust makes you think it's insignificant. It's just
Speaker 2: something to be blown off of. Something else. Man, it
Speaker 2: gets in your way, something, it messes things up, something
Speaker 2: to be gotten rid of. But dust has clues in it.
Speaker 2: This is like the dust here on Earth tells you
Speaker 2: who's been living there and the insects that have been around.
Speaker 2: Dust out in space tells you what's been happening in
Speaker 2: the universe, because there's dust makers and dust consumers, and
Speaker 2: dust also plays a big role in making stars and planets.
Speaker 1: Well, you just said dust consumers out in space like
Speaker 1: aliens who buy dust. That's what it sounds like.
Speaker 2: Not dust customers. You know, ways in which just is
Speaker 2: created and then dust is destroyed. I should say dust destroyers.
Speaker 1: Oh there you go. See that's a device. I would
Speaker 1: buy a dust destroyer.
Speaker 2: Wait till you learn how dust is destroyed. You don't
Speaker 2: want one of these things?
Speaker 1: Maybe I do. Let's find out. Well, as usual, we
Speaker 1: were wondering how many people had thought about the importance
Speaker 1: of cosmic does and what role it has in our
Speaker 1: search for the meaning of the universe and how it
Speaker 1: all works.
Speaker 2: Thanks to everybody who pitches in for this segment of
Speaker 2: the podcast. I hear from listeners that they really enjoy
Speaker 2: hearing your voices in your thoughts on the episode topic.
Speaker 2: If you would like to share your voice and thoughts,
Speaker 2: please don't be shy. Write me to Questions at Daniel
Speaker 2: Andandjorge dot com.
Speaker 1: So think about for a second, how important do you
Speaker 1: think cosmic dust is. Here's what people have to say.
Speaker 2: Stop waving from the universe. I would say that twenty
Speaker 2: percent is planet stars, black holes, sixty percent gus, and
Speaker 2: the rest twenty percent is dust.
Speaker 3: I think that this is the one of those questions
Speaker 3: that but you have to think about some things that
Speaker 3: you usually take for granted. So I would say that
Speaker 3: the QA is mostly composed by dust.
Speaker 1: All right, interesting, answers here, some people seem to interpret
Speaker 1: the questions like how significant is cosmic? Doest?
Speaker 2: Yeah?
Speaker 1: Like, or like how much how much of the universe
Speaker 1: is cosmic? Does?
Speaker 2: And they also seem to be taking it as a
Speaker 2: leading question, like because I'm asking it, they're figuring probably
Speaker 2: it's a big component of the universe and playing an
Speaker 2: important role.
Speaker 1: I see, it wouldn't be very interesting just the answer
Speaker 1: was just like not at all or nope, nobody cares.
Speaker 2: Yeah, Like how important are Daniel dirty socks?
Speaker 3: Yeah?
Speaker 2: Not interesting, not important? Move on, That wouldn't be a
Speaker 2: very fun episode.
Speaker 1: Let's not talk about your socks because I know you
Speaker 1: don't wear socks, so.
Speaker 2: Well, then it's a philosophy question, right can my socks
Speaker 2: be unimportant if they don't even exist?
Speaker 1: There you go, philosophy of footwear.
Speaker 2: Somebody out there is doing a whole PhD thesis on
Speaker 2: that topic, probably.
Speaker 1: On your socks. On socks, and Jackie, I know you're
Speaker 1: famous now, Daniel, but geez.
Speaker 2: No on socks? Why they disappear where they go? Why
Speaker 2: dryers consume them? See dryers are sock destroyers.
Speaker 1: Nay, it turns them into dust.
Speaker 2: Maybe it transports them to the hozone layer of the atmosphere.
Speaker 1: So let's dig into this topic, Daniel, what is cosmic dust?
Speaker 2: Cosmic dust is an important part of the Solar system,
Speaker 2: though it's not a big fraction of the Solar system.
Speaker 2: The answer from these listeners made me dig into the
Speaker 2: question of like, actually, but is the mass budget of
Speaker 2: the Solar system? How much of it is cosmic dust
Speaker 2: and how much of it is made of other stuff?
Speaker 1: So what's the breakdown?
Speaker 2: So the Milky Way weighs about one to one and
Speaker 2: a half trillion times the mass of the Sun. That's
Speaker 2: like our mass unit a solar mass, and the total
Speaker 2: Milky Way is about a trillion trillion and a half
Speaker 2: solar masses. Now, most of that, like ninety percent of
Speaker 2: that is dark matter. We know that the stuff that's
Speaker 2: visible in the universe, the stuff that glows, and even
Speaker 2: the stuff that doesn't glow that much, like rocks and
Speaker 2: dust and asteroids, that's only like ten percent of the
Speaker 2: mass of the Milky Way. Out there in the larger universe,
Speaker 2: dark matter is a little bit less common than it
Speaker 2: is here in the Milky Way. The Milky Way has
Speaker 2: more dark matter than an average galaxy.
Speaker 1: And I guess. How do we know these things? Like
Speaker 1: how do we know how much the Milky Way weighs?
Speaker 1: Do we put it on a scale or something.
Speaker 2: We can measure the component of the Milky Way independently
Speaker 2: and then add them up. The stars and the interstellar medium,
Speaker 2: the black hole, all that stuff we can measure independently,
Speaker 2: and then we can measure the total mass by looking
Speaker 2: at how fast the Milky Way is rotating. Because stars
Speaker 2: are like tracers, they move around the Milky Way, and
Speaker 2: their speed is determined by the gravitational traction of everything
Speaker 2: closer to the center than they are. Things further away
Speaker 2: from the center on the outer shell don't affect them
Speaker 2: at all, things on the inside do. So by reading
Speaker 2: the speed of these stars, we can tell how much
Speaker 2: mass they're radius encloses, and so that measures the total
Speaker 2: mass of the Solar system. And that's how we infer
Speaker 2: dark matter, sort of the left over bit that we
Speaker 2: can't account for with stars and planets and gas and dust.
Speaker 1: But we can't see all of the Milky Way right
Speaker 1: Like we're in the Milky Way, can we really see
Speaker 1: the full extent of it and have a good guess
Speaker 1: about its composition?
Speaker 2: There's a lot of uncertainty, which is why I said
Speaker 2: one to one and a half trillion solar masses. So
Speaker 2: that's like an uncertainty of five hundred billion solar masses.
Speaker 2: And yeah, part of that comes from the fact that
Speaker 2: we can't see the whole Milky Way because we're looking
Speaker 2: through it, we're inside of it, and the Milky Way
Speaker 2: has a good amount of dust in it, and that
Speaker 2: dust obscures our view. So there's a whole region of
Speaker 2: the Milky Way that we can't see very well in
Speaker 2: many frequencies of light, and that leads to a lot
Speaker 2: of this uncertainty. I see.
Speaker 1: So then how much of our Milky Way is dust?
Speaker 2: So it's like ninety percent dark matter, Then it's like
Speaker 2: three percent stars, it's like one hundred to two hundred
Speaker 2: billion stars. And then leftover is this stuff called the
Speaker 2: interstellar medium, which is maybe like half a percent or
Speaker 2: one percent of the mass of the Milky Way, and
Speaker 2: one percent of that is dust. The interstellar medium is
Speaker 2: mostly gas, it's like hydrogen and a little bit of helium.
Speaker 2: So one percent of the interstellar medium, which is one
Speaker 2: percent of the galaxy, is dust. So the dust is
Speaker 2: like point zho one percent or maybe half of that.
Speaker 2: It's a tiny fraction of the mass of the Milky Way.
Speaker 1: So I guess you don't count that gas is dust, right.
Speaker 2: That's right. And this is another example of humans putting
Speaker 2: categories on things where really there's a smooth spectrum. If
Speaker 2: we call it gas, it means it's like a molecule,
Speaker 2: there's like h two floating out there, we call that gas.
Speaker 2: If it's a larger clump of stuff, a bunch of
Speaker 2: molecules together, little grains down like one hundred nanometers or larger,
Speaker 2: we call that dust. Get much bigger, we start to
Speaker 2: call you like a meteor or an asteroid or even
Speaker 2: a planet. But in the end, there's a whole spectrum
Speaker 2: all the way down from individual molecules which we call gas,
Speaker 2: to larger clumps of stuff which we call dust, all
Speaker 2: the way up to much bigger objects stars and planets.
Speaker 1: I guess at some point you get to like pebbles, right,
Speaker 1: and little rocks. Is there such a thing as space sand?
Speaker 2: Well, you know this dust is made of carbon and silicates, right,
Speaker 2: and sand is mostly silicates. So in the end, like
Speaker 2: a lot of this space dust is kind of like
Speaker 2: super fine grains of sand.
Speaker 1: But then I also imagine there is sort of sand
Speaker 1: sized grains out there in space.
Speaker 2: There are larger pieces for sure, And so this intermedia
Speaker 2: category we call dust is not a very big fraction
Speaker 2: of the mass of the Milky Way. But to compare,
Speaker 2: it's about the same mass as the central black Hole.
Speaker 2: Point oh one percent of the Milky Way sounds like
Speaker 2: a tiny number. It's a tiny percentage of a huge number, right,
Speaker 2: one and a half trillion solar masses. So it comes
Speaker 2: out to be about the mass of the central black Hole.
Speaker 1: And so where did all this dust come from? Like
Speaker 1: are there giant space aliens shedding of their skin?
Speaker 2: To understand where the dust comes from, we need to
Speaker 2: dig into a little bit more about like what is
Speaker 2: this dust? And it's made of like a bunch of
Speaker 2: different stuff, some tiny little portion of it, this is
Speaker 2: really fascinating, comes from the atmospheres of stars. We know
Speaker 2: that stars their job is to take hydrogen and helium
Speaker 2: and lighter elements and fuse them into heavier elements, although
Speaker 2: I have to iron and even heavier in the case
Speaker 2: of supernova and in the atmospheres of these stars, especially
Speaker 2: when they get really really big and near the end
Speaker 2: of their life. Their atmospheres produce these little grains. They're
Speaker 2: like coalesce as they cool, and the outflow in the
Speaker 2: atmosphere of these stars. That's sort of like one source
Speaker 2: of this stuff. But if you look out into the
Speaker 2: universe and study this stuff, most of it is not
Speaker 2: these presolar grains, these like pristine little blobs made in
Speaker 2: the atmospheres of stars. Most of it's been like reprocessed,
Speaker 2: like shattered and ground up and reformed into new bits.
Speaker 1: Interesting just from like the churning of space, of stuff
Speaker 1: in space.
Speaker 2: Just from the churning of space. It turns out that
Speaker 2: you can't just hang out as a grain in the
Speaker 2: middle of space. There are processes happening out there. There
Speaker 2: are processes that destroy dust and processes that reform it.
Speaker 2: The dust destroyers that are out there. It sounds like,
Speaker 2: you know, some big alien ship coming along to clean
Speaker 2: up the universe, but actually it's shock waves from supernova.
Speaker 2: When supernova collapse and then explode, they produce these huge
Speaker 2: shock waves, massive amounts of energy, gamma, rays, neutrinos, all
Speaker 2: sorts of stuff, and that comes along and it shatters
Speaker 2: these grains, destroying the dust and breaking it like back
Speaker 2: down into gas.
Speaker 1: Well you know they say space is just a big vacuum,
Speaker 1: so those are just suckle. Anyways, So you were saying
Speaker 1: that dust is important in the universe. Is it important
Speaker 1: to the universe or just to our understanding or to
Speaker 1: our search for answers about the universe?
Speaker 2: Well both, Like the history of dust tells us what's
Speaker 2: happened out there in the universe. You can take each
Speaker 2: individual solar grain if it survived this like interstellar shattering process,
Speaker 2: and some of them have, and you can trace it
Speaker 2: back to an individual star. Like every star has a
Speaker 2: different mixture of elements and a different mixture of isotopes,
Speaker 2: so they leave special fingerprints in their solar grains, and
Speaker 2: so like ular grain can tell you, like what that
Speaker 2: star was. It's like a little sample from that star.
Speaker 2: And some of them are made during supernova and capture
Speaker 2: elements and isotopes that only exist, we think, in the
Speaker 2: atmospheres of supernova during those brief moments that are super
Speaker 2: energetic and can tell us about the formation of heavy
Speaker 2: elements and what's going on in supernova. So there are
Speaker 2: these amazing capsules that tell us about the history of
Speaker 2: the universe.
Speaker 1: But I think maybe you don't mean like each individual grain,
Speaker 1: do you look? You maybe need like a population or
Speaker 1: like a cloud of this dust to sort of know
Speaker 1: what the star was like.
Speaker 2: Well, each individual grain tells you something about that star.
Speaker 2: Not every grain produced by the star is identical, right,
Speaker 2: and the star has a variety of stuff in it,
Speaker 2: but each one traces back to an individual star.
Speaker 1: Just each grain would be made out of different things.
Speaker 2: Yeah, each star would make different kinds of grains. There's
Speaker 2: going to be some overlap. It's not completely unique, right,
Speaker 2: But each star is made out of different kinds of stuff,
Speaker 2: different elements, different mixtures. Each star is a slightly different
Speaker 2: mass and temperature and so produces different mixtures of stuff
Speaker 2: and different isotopes, and so the grains produced by each
Speaker 2: star are different.
Speaker 1: Like an individual grain would have different things in it
Speaker 1: and different signatures in it.
Speaker 2: Yeah, exactly. The isotopes found in an individual grain tell
Speaker 2: you about the star that it came from.
Speaker 1: Mmmm. Interesting, So how is it important to the universe itself?
Speaker 1: Because it doesn't seem like it weighs a lot in
Speaker 1: the Milca way, So maybe I wonder if it has
Speaker 1: a big role in you know, the dynamics of space.
Speaker 2: It does play a big role in the dynamics of
Speaker 2: space sort of for two reasons. One is that stuff
Speaker 2: heavier than gas is the reason that we have like
Speaker 2: planets and stars and stuff like that. Like the Earth
Speaker 2: is mostly made out of stuff that's not just hydrogen
Speaker 2: and helium, right, and that's cosmic dust gathered together to
Speaker 2: form planets. So most of the rocky stuff of the
Speaker 2: Solar system came originally from what we would call cosmic dust, right,
Speaker 2: those heavier elements that are created by stars and spewed
Speaker 2: out into space. And also we think that this cosmic
Speaker 2: dust plays a role in the formation of solar systems.
Speaker 2: You have a huge gas cloud that eventually collapses into
Speaker 2: a bunch of stars. Why does it collapse. It collapses
Speaker 2: because it's a little spot here that's denser, that's heavier,
Speaker 2: that's cosmic dust. Man, Those are like the iron grains
Speaker 2: and the little bits of heavy elements floating around that
Speaker 2: seed that gravitational collapse.
Speaker 1: Wait, are you saying the Bible was right? We all
Speaker 1: come from dust, from dust to dust.
Speaker 2: And even ashes, right, star ashes.
Speaker 1: Cool And so then how does it help us study
Speaker 1: the universe or how does it not help us study
Speaker 1: the universe.
Speaker 2: Yeah, it both hurts our ability to study the universe
Speaker 2: and helps us. Like it prevents us from seeing things
Speaker 2: in the universe because it absorbs light and it blocks
Speaker 2: our view. The center of the Milky Way, which is
Speaker 2: choked with dust, is famously called by astronomers the zone
Speaker 2: of avoidance because they have to look away from that region.
Speaker 2: You can't see through the center of the Milky Way
Speaker 2: in optical lights, so you can't see what's on the
Speaker 2: other side of the galaxy very easily. So it's sort
Speaker 2: of a pain for astronomers, but it also captures this
Speaker 2: history right, And in order to understand the cycles of
Speaker 2: star formation in the universe, we do have to understand
Speaker 2: the cosmic dust because the cosmic dust plays a role
Speaker 2: in the formation of those stars and is also then
Speaker 2: destroyed by the supernovas and then reforms. It's all part
Speaker 2: of the cycle of the Milky Way. You might imagine
Speaker 2: the Milky Way is just like a bunch of stars
Speaker 2: floating in space basically doing nothing, but it's churning and burning.
Speaker 2: This stuff going on just sort of much longer time
Speaker 2: scales than we're used to thinking about.
Speaker 1: Hmm. Interesting all right, Well, let's get into how we
Speaker 1: know where the dust in the universe is and the
Speaker 1: very important question where does it all come from? Who's
Speaker 1: making this mess in the universe. So let's dig into that,
Speaker 1: But first let's take a quick break. All right, we're
Speaker 1: talking about cosmic dust, which is not a drug, I imagine,
Speaker 1: so it sounds like it might be something you'd sell
Speaker 1: on the streets.
Speaker 2: I don't know. If you walk down the street in
Speaker 2: Berkeley and you ask people for cosmic dust, I'm pretty
Speaker 2: sure they'll sell you something.
Speaker 1: They'll sell you something. But we're talking about the dust's
Speaker 1: out there in space between the stars, and it's important
Speaker 1: because we're all made out of dust. Stars and planets,
Speaker 1: they're all essentially come from dust that gravity pulls together,
Speaker 1: and so it's important for that reason. But it also
Speaker 1: sort of helps us understand the origins of stars in
Speaker 1: the universe.
Speaker 2: Right, even though it's tiny, it's a little bitty part
Speaker 2: of the mass budget of the Solar system. It tells
Speaker 2: about how things work and it plays a role in
Speaker 2: getting those things started.
Speaker 1: But I imagine maybe at some point in the universe's
Speaker 1: history dust it was all dust, basically, right, That's where
Speaker 1: all those stars came from No, I guess you went
Speaker 1: from gas to stars and then those made dust exactly.
Speaker 2: We think that the universe began and dust lists right.
Speaker 2: So it's actually an interesting open question in astronomy right now.
Speaker 2: It is like when was the first dust made? People
Speaker 2: really want to understand the process by which dust is
Speaker 2: created and destroyed and helps form new stars, and there's
Speaker 2: a lot of open questions out there. We don't really
Speaker 2: fully understand the process of it. But we're pretty sure
Speaker 2: that the universe began with just hydrogen and helium and
Speaker 2: the tiny trace elements of things heavier and no larger
Speaker 2: molecules of course, and it's only when stars began to
Speaker 2: burn that dust was created.
Speaker 1: But I wonder if in the Big Band, you know,
Speaker 1: things were so intense, there was so much pressure, there
Speaker 1: was so much violent processes going on, so many of
Speaker 1: those that I wonder if some hydrogens aret it e
Speaker 1: merging together and make dust without any stars? Is that possible?
Speaker 2: With the earliest dust we've seen is like several hundred
Speaker 2: million years after the Big Bang, and it's possible that
Speaker 2: hydrogen formed and crystallized somehow earlier on. I don't think
Speaker 2: we would call that cosmic dust. Though if it's just
Speaker 2: pure hydrogen, probably you just call that hydrogen crystals. I
Speaker 2: think to be called dust probably needs to have some
Speaker 2: like carbon and some silicon and some heavier elements in it.
Speaker 1: But I mean, could a little bit of a carbon
Speaker 1: and silicon have formed in the big during the Big Bang?
Speaker 2: Big Bang nuclear synthesis is a pretty precise science, and
Speaker 2: it tells us, based on the temperature and like the
Speaker 2: cork density, exactly how much of what was made. And
Speaker 2: we think that it's almost overwhelmingly hydrogen, with just tiny
Speaker 2: trace elements of helium and then little tiny, anty bitty
Speaker 2: bits of heavier stuff carbon. Probably not because carbon requires
Speaker 2: the merging of three helium simultaneously. Because lithium is so unstable,
Speaker 2: so very unlikely that any carbon was formed, but you
Speaker 2: can't say no, it's possible there were tiny, tiny grains
Speaker 2: of carbon form during the Big Bang.
Speaker 1: So there could be primordial dust out there, like og dust.
Speaker 2: That's right, The most ancient dust is possible, though the
Speaker 2: oldest dust we've ever seen is a few hundred million
Speaker 2: years after the Big Bang.
Speaker 1: All right, Well, that brings us to our next question,
Speaker 1: which is, how do we know where the dust in
Speaker 1: the universe is. It doesn't glow in space, right, It.
Speaker 2: Actually kind of does glow in space, not the way
Speaker 2: that stars do. Right. Stars create their own light through fusion.
Speaker 2: They light up the whole universe. But everything out there
Speaker 2: has a temperature, and everything that has a temperature glows.
Speaker 2: Even the Earth glows. Right. It gives off infrared radiation,
Speaker 2: and so dust glows in the very very infrared because
Speaker 2: dust is pretty cold. So you can see the dust
Speaker 2: if you use telescopes that can see infrared light and
Speaker 2: so like the Spitzer Space Telescope and a James Web
Speaker 2: Space telescope. These things out there can see dust in
Speaker 2: our galaxy and in other galaxies by its thermal emissions.
Speaker 1: Like I guess you could tell where there was a
Speaker 1: lot of dust and where there isn't a lot of dust.
Speaker 2: Yeah, exactly. You can't see an individual grain. You can
Speaker 2: see like huge clouds of dust here and there. You
Speaker 2: can see it glowing in the very far infrared. You
Speaker 2: can also see dust by how it blocks light. Like
Speaker 2: we think we understand how stars glow and the light
Speaker 2: that they give off, and dust blocks that light. You know,
Speaker 2: it absorbs some frequencies of it, it reflects other frequencies of it,
Speaker 2: and so by looking at what astronomers call the extinction curve,
Speaker 2: like where's light being blocked, they can measure how much
Speaker 2: dust there is between us and something.
Speaker 1: So we measure it by how it much it blocks light,
Speaker 1: not how much it reflects light.
Speaker 2: We measure it by how much it blocks light and
Speaker 2: also emits a little bit of light in the infrared,
Speaker 2: so it depends a lot on the frequency it will reflect.
Speaker 2: Blue light mostly infrared light can mostly pass through dust
Speaker 2: shorter frequencies where the light has like roughly the wavelength
Speaker 2: of the dust that will get reflected or absorbed. So
Speaker 2: when light passes through a dust cloud, it basically gets
Speaker 2: reddened because the blue light gets reflected and the red
Speaker 2: light makes it through.
Speaker 1: It's a little bit of the opposite of what happens
Speaker 1: here during the sunset. No, it's the same.
Speaker 2: It's the same. The light gets reddened, right, the atmosphere
Speaker 2: tends to reflect blue light, so the sky looks blue
Speaker 2: because in direct sunlight it's scattered down to your eye.
Speaker 2: That at sunset, the light is coming straight at you
Speaker 2: and the blue light is being reflected away and you're
Speaker 2: seeing the red light. Mm.
Speaker 1: It filters like it filters out blue light.
Speaker 2: M hmm, exactly, it filters out blue light. And so
Speaker 2: when astronomers look out into the sky, they can see
Speaker 2: that some stars appear to be dimmed, and they appear
Speaker 2: to be dimmed differently across the spectrum. Right, It's not
Speaker 2: just like the whole star is dimmer, which might mean
Speaker 2: it just further away, but it's dimmed more in the
Speaker 2: red than in the blue. So these extinction curves are
Speaker 2: really important for astronomers to study because every time they're
Speaker 2: looking at something in the universe, they want to know,
Speaker 2: like how much dust are we looking through? How much
Speaker 2: is dust distorting what we're seeing?
Speaker 1: So technically, does that mean that dust, this space dust
Speaker 1: is blue like if you were well, when you sort
Speaker 1: of look at it, it's blueish.
Speaker 2: I guess it reflects blue light. It glows in the
Speaker 2: far infrared, but it reflects blue light, so I guess
Speaker 2: that would make it kind blue.
Speaker 1: Yeah, And have we ever like got in a sample
Speaker 1: of dust, Like, have we ever gone out there and
Speaker 1: grabbed a you know, vacuum up some dust to study it?
Speaker 2: We do actually have samples of space dust. It's super fascinating.
Speaker 2: All the dust that we have sampled is only stuff
Speaker 2: in our solar system, so we've never sampled stuff outside
Speaker 2: of our solar system. The furthest probes we ever sent
Speaker 2: have like just barely left the Solar system. But there's
Speaker 2: plenty of space dust here in our solar system, and
Speaker 2: many many satellites that we send have little dust collectors.
Speaker 2: It's kind of a challenge because these satellites are moving
Speaker 2: in very high speeds relative to the dust, so it
Speaker 2: can be trickyed like catch the dust. But there are
Speaker 2: some missions like the Star Dust Mission, specifically to capture
Speaker 2: dust and bring it back, But then lots of other
Speaker 2: satellites have like a little space dust collector on it.
Speaker 2: We talked once about the JUNO mission that went to
Speaker 2: Jupiter in twenty eleven had sort of an accidental star
Speaker 2: dust collector on it. The dust was slamming into the
Speaker 2: back of the solar panels on the satellite and then
Speaker 2: spilating off little bits which you got picked up by
Speaker 2: a camera, and it turned out to be like a
Speaker 2: huge effective dust collector, and this is how we learned
Speaker 2: that Mars is giving off all of this dust, which
Speaker 2: is probably responsible for causing the zodiacal light. We have
Speaker 2: also captured some dust and broad down to Earth and
Speaker 2: studied it under a microscope and seeing like some fractions
Speaker 2: of this stuff really are presolar grains, bits of dust
Speaker 2: that are older than our solar system. Oh, super old dust,
Speaker 2: super old dust. Our solar system is like four and
Speaker 2: a half billion years old. But of course stars have
Speaker 2: been around for much longer than that, and some of
Speaker 2: them died and created these grains, which amazingly survived out
Speaker 2: there in space and then formed into asteroids or formed
Speaker 2: as part of the Earth, or still just floating out there.
Speaker 2: It's incredible that some of these little grains have lasted
Speaker 2: so long.
Speaker 1: And we also know how much dust is out there
Speaker 1: because it's polarized, right, It's got some sort of electrical charge,
Speaker 1: noess to it.
Speaker 2: Yeah, the dust grains are not spherical, right, They have
Speaker 2: little shapes. They're irregular, which means that they tend to
Speaker 2: be longer in one direction than another. And because they're
Speaker 2: made of electromagnetic stuff, sometimes they have an overall charge.
Speaker 2: You know. The dust like bumps against itself, it gets
Speaker 2: like static electricity essentially, and then interstellar space it will
Speaker 2: align with magnetic fields, you know, the Earth has a
Speaker 2: magnetic field, the Sun has a magnetic field, the whole
Speaker 2: galaxy has magnetic fields. We think there might even be
Speaker 2: magnetic fields out there in between superclusters. We talked once
Speaker 2: about primordial magnetic fields. Anyway, the dust grains are a
Speaker 2: great way to measure those magnetic fields because they align
Speaker 2: with the magnetic fields, and then when light passes through them,
Speaker 2: it tends to polarize the light because the dust itself
Speaker 2: is pointing in a specific direction. So light passing through
Speaker 2: this region can tell you about the dust and about
Speaker 2: the magnetic fields in that region. It's sort of an amazing
Speaker 2: way to like learn about these huge regions of space
Speaker 2: which otherwise look empty.
Speaker 1: Well, it's like having special glasses to see the universe.
Speaker 2: Yeah, exactly. So we have lots of ways to study
Speaker 2: cosmic dust and to look at the spectrum. And you know,
Speaker 2: looking at the spectrum also tells you what's in there,
Speaker 2: because if it has like a certain crystal, then that
Speaker 2: crystal has rotational and vibrational frequencies and they will absorb
Speaker 2: with those frequencies or emitted those frequencies, and so they
Speaker 2: can tell what's in cosmic dust. Even if we can't
Speaker 2: sample it, like cosmic dust is far far away in
Speaker 2: the milky Way. They can tell what it's made out
Speaker 2: of based on how it glows and how it absorbs light.
Speaker 1: Hmmm, because that can change, I guess, depending on what
Speaker 1: was happening there that made the dust exactly.
Speaker 2: Because cosmic dust is not static, right. One of the
Speaker 2: big mysteries is like where's all this cosmic dust come from?
Speaker 2: And you know, we think that a lot of it
Speaker 2: is made in stars. It's made in supernova, It's made
Speaker 2: in these stars called asymptotic giant branch stars. It's made
Speaker 2: in super red giant stars to have like just the
Speaker 2: right conditions in their atmosphere to coalesce this stuff, like
Speaker 2: outflowing and cooling gases will create these grains and shoot
Speaker 2: them out into the universe. And that's cool, but it
Speaker 2: can't explain all the dust that we see out there.
Speaker 2: There's like not enough stars and not enough for of
Speaker 2: this dust to explain all the dust that's out there
Speaker 2: in the universe. Because, as we said earlier, the dust
Speaker 2: doesn't survive forever. Right. The dust is like shattered by supernova.
Speaker 2: So we have like stars pumping dust out in the
Speaker 2: universe supernova shattering it back in the gas, and that
Speaker 2: leaves sort of a mystery because there's not enough being
Speaker 2: made by the stars to explain all the stuff that
Speaker 2: we see out there, all the dust in the Milky
Speaker 2: Way I see.
Speaker 1: So like dust is sort of like they're bigger molecules basically, right,
Speaker 1: they're like little tiny pebbles, and inside of the stars
Speaker 1: they just burn up I guess, right, because it's so
Speaker 1: hot and under so much pressure.
Speaker 2: Yeah, that's why they're made. Like in the outer atmosphere,
Speaker 2: the outflowing and cooling gases coalesced into these grains. If
Speaker 2: that ever happened inside the star, that would just burn
Speaker 2: up as fuel.
Speaker 1: Yeah, like the carbon and all the silicon. It's sort
Speaker 1: of gassy within the sun, but once it gets out
Speaker 1: of the Sun, it tends to form into molecules and
Speaker 1: maybe little clumps mm hmm. But then you're saying like,
Speaker 1: once it's out there in space, then if there's a supernova,
Speaker 1: the supernova breaks it up back into carbon and silicon exactly.
Speaker 2: So like the typical lifetime for a grain of dust,
Speaker 2: it's like one hundred million years. It can float out there,
Speaker 2: and then on average it's going to get shattered after
Speaker 2: about one hundred million years, some longer, some shorter, but
Speaker 2: on average one hundred million years.
Speaker 1: There are that many supernovas happening that to shatter does
Speaker 1: so frequently.
Speaker 2: There are not that many supernovas, but they're frequent enough
Speaker 2: and powerful enough to shatter this cosmic dust.
Speaker 1: So like on average, for any point in space, you
Speaker 1: experience this shattering supernova every hundred million years.
Speaker 2: Yeah, the supernova are more common than every hundred million years.
Speaker 2: There's a supernova in our galaxy roughly every fifty years,
Speaker 2: so in one hundred million years, you're going to get
Speaker 2: two million supernova across the galaxy and they're very very powerful.
Speaker 2: So the modeling at least tells astronomers that these things
Speaker 2: should be shattered on average within one hundred million years.
Speaker 1: But the Earth has been around longer than that, and
Speaker 1: have we experienced such as shattering supernova.
Speaker 2: The Earth has been around much longer than that, but
Speaker 2: it would take a very close by supernova to shatter
Speaker 2: the Earth. These grains are more delicate than Earth, which
Speaker 2: has been like compressed right.
Speaker 1: M So like if there's a bit of dust circling
Speaker 1: the Earth, it would get shattered by the supernova, but
Speaker 1: not our atmosphere or US.
Speaker 2: Yeah, dust is more fragile. You know, it's floating out
Speaker 2: there into space. It's very low pressure. These things are
Speaker 2: sort of fragile compared to like a rock on Earth.
Speaker 1: All right, So then the mystery you're saying is like
Speaker 1: how it's made?
Speaker 2: Then, Yeah, the mystery is like why is there still
Speaker 2: so much of it? There's a lot more cosmic dust
Speaker 2: out there than can be explained by this combination of
Speaker 2: stars producing it and then supernova's destroying it. There's a
Speaker 2: lot more cosmic dust that can be explained by just
Speaker 2: that process.
Speaker 1: Maybe the unergy just hasn't bought that neat device you
Speaker 1: have to get rid of dust.
Speaker 2: Well, one theory about what's going on is that cosmic
Speaker 2: dust itself can reform out there between the stars. So
Speaker 2: you take these little pebbles, these little grains, you send
Speaker 2: them out there. They get shattered back into gas, but
Speaker 2: there's like a tiny little seed left, you know, a
Speaker 2: few molecules still cleaning together, and then those can accrete
Speaker 2: because they're flowing through these molecular clouds which are super
Speaker 2: duper cold, and basically because you have a few tiny,
Speaker 2: little grains left, they can like pick up more like
Speaker 2: ice can form on these things, and you get these
Speaker 2: layers that surround the original tiny core that rebuilds this
Speaker 2: thing back up into what you would call dust.
Speaker 1: I see. Yeah, just reforms because and also because of gravity.
Speaker 1: I imagine, right, like even if you split a little
Speaker 1: grain of dust out there, eventually, gravity is going to
Speaker 1: put it back together, isn't it.
Speaker 2: Yeah, exactly? And you know that's the process that eventually
Speaker 2: forms stars and planets, right, These little gravitational seeds gathered
Speaker 2: together over very long periods, but it begins with gathering
Speaker 2: little bits of ice here and there and reforming. And
Speaker 2: so some of the cognic dust that's out there are
Speaker 2: like og grains that came from their stars and haven't
Speaker 2: been shattered, but most of it probably comes from this
Speaker 2: process where they have been shattered and then they coalesce,
Speaker 2: collecting ice and reforming into grains.
Speaker 1: All right, Well, you mentioned that there are some things
Speaker 1: called dust destroyers out there in space and also mysterious
Speaker 1: ways that dust is made, and so let's dig deeper
Speaker 1: into those things. But first let's take a quick break. Okay,
Speaker 1: we're talking about dust and Daniels you're saying, the big
Speaker 1: question is where does it come from? Because most of
Speaker 1: the dust. If you just put dust out there in space,
Speaker 1: within one hundred million years, some distant supernova's shockwave is
Speaker 1: gonna shatter that back into its constituent atoms like carbon
Speaker 1: and slogan. It doesn't seem that fragile here on Earth, right,
Speaker 1: Like if I blow on dust, it doesn't break up
Speaker 1: into carbon gas.
Speaker 2: I mean, you're pretty tough, dude, But are you saying
Speaker 2: that your breath is as powerful as a supernova?
Speaker 1: Well, some mornings, yeah, But I mean, like it's weird
Speaker 1: to think that it's so powerful because here on Earth
Speaker 1: we don't feel these supernovas. But you're saying it's drying
Speaker 1: enough to like split apart molecules in space.
Speaker 2: The dust is more fragile than the Earth is. Yeah,
Speaker 2: and it hasn't been a supernova in our Milky Way
Speaker 2: in quite a few hundred years, so it's not like
Speaker 2: we're feeling these things every ten years or so. Even
Speaker 2: these supernovas are not that common. But yeah, the lifetime
Speaker 2: of dust is shorter than the lifetime of the Earth.
Speaker 2: So the Earth and planets and stars definitely survived these
Speaker 2: super nova shock waves in ways that the stellar dust doesn't.
Speaker 1: So then the mystery is, like, if it is being
Speaker 1: destroyed out there in space, why is there still dust?
Speaker 1: Why is in and auges gas and individual atoms exactly?
Speaker 2: And it's important that the dust is there because the
Speaker 2: dust seeds planetary formation and star formation, you know, in
Speaker 2: ways that we didn't always understand. Like back in the seventies,
Speaker 2: before we really understood cosmic dust at all, people thought
Speaker 2: that our solar system started just from gas, that you
Speaker 2: could start from just like a blob of hydrogen and
Speaker 2: helium and form all of this stuff, which doesn't really
Speaker 2: make sense to me because then like where you're getting
Speaker 2: all the iron and all this stuff to make planets.
Speaker 2: But now it's very well understood that most of the
Speaker 2: iron and most of the heavy metals are bound up
Speaker 2: in these cosmic dust grains and you need them to
Speaker 2: form solar systems with interesting bits on them like rocks
Speaker 2: and people.
Speaker 1: So then are you saying that like just gravity, you know,
Speaker 1: pulling all of this stuff out there floating in space
Speaker 1: into dust is not enough to account for the dust
Speaker 1: we're seeing, Well, why not?
Speaker 2: So just stellar production of dust isn't enough to account
Speaker 2: for the dust that we're seeing. You need some way
Speaker 2: to reform dust in the interstellar medium, otherwise, as you say,
Speaker 2: it would be just gas. But we think that these
Speaker 2: little grains probably do gather back together from gravity and
Speaker 2: from deecretion of ice crystals. As you pass through a
Speaker 2: molecular cloud, there's going to be chemical bonds that form
Speaker 2: because these things are a little sticky, right, And so
Speaker 2: that is a process that they think might explain where
Speaker 2: the gas comes from. I talked to one scientist at
Speaker 2: the University of Wasita in Japan who's super interested in
Speaker 2: cosmic dust, and she said that this is like the
Speaker 2: leading theory for how cosmic dust is being regenerated. But
Speaker 2: nobody's like demonstrated this in the lab. They haven't done
Speaker 2: tests where they take like a little grain and pass
Speaker 2: it through a dust cloud and see this stuff reform.
Speaker 2: It's alsort of like theoretical chemistry at this point.
Speaker 1: Well, you need to replicate zero gravity, wouldn't you.
Speaker 2: Yeah, exactly. It's the kind of experiment you'd want to
Speaker 2: do out in space or on the iss or something.
Speaker 1: So then that's the best answer to this mystery.
Speaker 2: That's the best answer to this mystery.
Speaker 1: So it sounds like you're saying, like there's a giant
Speaker 1: vacuum in space just gathering all this stuff dust.
Speaker 2: Well, you know again it's the supernova, right, Those are
Speaker 2: the dust stories shattering it back into gas, and then
Speaker 2: they think that it's probably reforming. But another really fascinating
Speaker 2: way that they're trying to understand this process is by
Speaker 2: trying to answer a related question, which is like how
Speaker 2: early did dust form in the universe. So now that
Speaker 2: we have like a super powerful infrared telescope, we can
Speaker 2: look deeper into the history of the universe and look
Speaker 2: for evidence of dust very very early on, like what
Speaker 2: is the oldest dust that we can see in the universe,
Speaker 2: and they'll give us a sense for these processes because remember,
Speaker 2: like stars didn't turn on for a few hundred million years,
Speaker 2: so the origin of the dust can really tell us
Speaker 2: about like who is making this dust?
Speaker 1: Right I think I mean, like if you look out
Speaker 1: into deep space with your telescopes, you're looking back in time,
Speaker 1: so like the light you're getting from those deep places
Speaker 1: in the universe is really old light, which might be
Speaker 1: old dust exactly.
Speaker 2: And we think that most of the dust out there
Speaker 2: in the universe right now is probably produced by these
Speaker 2: super red giant stars and this asymptotic giant branch stars.
Speaker 2: These special stars are super big and have just the
Speaker 2: right conditions for this, like outflowing gas to cool and
Speaker 2: form these little blobs which then flow down into space.
Speaker 2: But the James Web Space Telescope recently saw direct evidence
Speaker 2: for really really old grains of stars, like several hundred
Speaker 2: million years or up to a billion years after the
Speaker 2: Big Bang, too long ago for these stars, Like, we
Speaker 2: don't think that there were these super red giant stars
Speaker 2: early on in the universe. So probably the first dust
Speaker 2: made in the universe were made by supernova from the
Speaker 2: first generation of stars.
Speaker 1: WHOA wait, so how do we know we're looking at
Speaker 1: dust that old.
Speaker 2: Because we're looking at images of galaxies that are super
Speaker 2: duper far away. And so you can look at a
Speaker 2: galaxy and you can understand from its red shift how
Speaker 2: fast it's moving away from us, and therefore how far
Speaker 2: away it is, and therefore the age of the thing
Speaker 2: we're looking at.
Speaker 1: Isn't most of that light coming from the stars in
Speaker 1: the galaxy.
Speaker 2: Yeah, most of that light does come from the stars,
Speaker 2: But we're looking at an infrared telescope, and stars are
Speaker 2: much quieter in the infrared, so we're seeing information from
Speaker 2: the dust also.
Speaker 1: Oh, I see, like we see the galaxy with a
Speaker 1: regular light and then we switch the filter over to infrared,
Speaker 1: and then you're basically getting the light from the dust.
Speaker 2: Exactly, and specifically, what they're seeing here is extinction, right.
Speaker 2: They're seeing an absorption feature at a very specific wavelength
Speaker 2: twenty one seventy five inkstrums that they think is like
Speaker 2: a dust wavelength, that that's what dust absorbs. So they
Speaker 2: see like a dip in the light in this galaxy
Speaker 2: at just the right wavelength that tells them that there
Speaker 2: is dust in this very very old galaxy.
Speaker 1: Oh, because I guess the size of your thing affects
Speaker 1: what kind of light you're absorbing, right, because you kind
Speaker 1: of have to be at about the same size as
Speaker 1: the wavelength to absorb it exactly.
Speaker 2: Earlier we were talking about how dust absorbs as various frequencies.
Speaker 2: In general, the picture is that it interacts more with
Speaker 2: blue light. It reflects that blue light, and it doesn't
Speaker 2: interact as much with redor light because, as you say,
Speaker 2: it's too small, like the wavelength of light is bigger
Speaker 2: than these dust grains so it doesn't interact with them.
Speaker 2: But also these things contain specific chemicals and sometimes little crystals,
Speaker 2: and those have features that absorb at certain wavelengths, like
Speaker 2: little oscillations and vibrational energy levels of these little crystals
Speaker 2: inside these dust grains will absorb at specific wavelengths that
Speaker 2: are known to be dust wavelengths. So they saw this
Speaker 2: in this signature from the James Web Space telescope from
Speaker 2: the duper Ancient galaxy, a galaxy too old to whole
Speaker 2: any of these red giant stars or ASB stars. So
Speaker 2: they think probably this is ancient dust, maybe from the
Speaker 2: first round of generation of dust in the universe, probably
Speaker 2: from supernova.
Speaker 1: Like the first supernova's right, because that's that's when the
Speaker 1: heavier elements are made.
Speaker 2: And it's fascinating because supernova make this stuff and then
Speaker 2: also destroy it, so they kind of like clean up
Speaker 2: after themselves.
Speaker 1: Right, Wait, how can it make them and destroy them
Speaker 1: at the same time.
Speaker 2: These dust grains are made by supernovas sort of in
Speaker 2: the last dying minutes of a star's life, where you know,
Speaker 2: these shockwaves create really intense environments and specific isotopes, and
Speaker 2: then the outflow and the cooling makes these grains, but
Speaker 2: then shockwaves from supernova's also destroy dust. Right, supernova are
Speaker 2: the dust destroyers of the universe, So they both create
Speaker 2: it and they also are responsible for destroying it.
Speaker 1: Which do they do first? Do they first clean up
Speaker 1: and then put a bunch of dust there or do
Speaker 1: they put a bunch of dust and then immediately destroy it.
Speaker 1: Can't be the latter, can it, because then we wouldn't
Speaker 1: have any dust.
Speaker 2: It must be that the shockwave from the supernova travels
Speaker 2: out faster than dust grains, which means the first they're
Speaker 2: cleaning up and then they're making a mess. So I
Speaker 2: guess you're right. Actually it's in the wrong order. Or
Speaker 2: they're destroying the dust grains from other supernovas and to
Speaker 2: make space for their own.
Speaker 1: So they're not cleaning up after themselves. They're just cleaning
Speaker 1: it so that they can make a mess.
Speaker 2: Yeah, they're sort of like scrubbing the graffiti off the
Speaker 2: wall and then writing their own name on it.
Speaker 1: Yeah.
Speaker 2: I take it back. I take back everything positive I
Speaker 2: said about supernovas well.
Speaker 1: They're the reason we're here, so glad they haven't wiped
Speaker 1: us off. I guess I'm we're glad that they made us.
Speaker 1: All right, Well, what does it all mean about our
Speaker 1: understanding of the history of the universe.
Speaker 2: It means that all these processes, the ones that form stars,
Speaker 2: that lead to supernovas, that lead to dust creation and
Speaker 2: dust destruction, it's all part of this huge cosmic dance.
Speaker 2: You know. We tend to think of the Milky Way
Speaker 2: as like done, We've made all these stars. They're just
Speaker 2: sort of like hanging out and burning now. But it's
Speaker 2: a process, you know, and everything is connected as like
Speaker 2: dust flowing and swirling. These things are being created, they're
Speaker 2: being destroyed, they're being reformed. The whole thing is a big, frothing, active,
Speaker 2: lively mess of processes, all of which are important to
Speaker 2: creating the universe as we know it.
Speaker 1: Yeah, and it sounds kind of precarious, right, Like basically,
Speaker 1: we need a supernova to make all this dust, and
Speaker 1: we need the dust to basically clump together into planets
Speaker 1: and stars quickly before the next supernova tries to wipe
Speaker 1: the board clean. Right, Like if another supernova had gone
Speaker 1: off near us, or not even neros, but around us,
Speaker 1: before the Sun, you know, got put together and the
Speaker 1: Earth got put together, we might not be here. Is
Speaker 1: that true?
Speaker 2: It definitely would have affected things, but it's not something
Speaker 2: we understand very well. And supernova's contribute in lots of
Speaker 2: different ways. Like first of all, they destroy these grains,
Speaker 2: but then later on a supernova shockwave can actually precipitate
Speaker 2: the gravitational collapse of surviving grains into a new star.
Speaker 2: So supernova shockwaves play lots of different complex roles. And
Speaker 2: to say like that we even understand this story would
Speaker 2: be to overstate it. For sure, there's a lot of
Speaker 2: parts of this that we still don't understand. What we
Speaker 2: do know is that it's complicated and everything is connected.
Speaker 1: Sounds like our knowledge of it is a little dusty.
Speaker 2: There's definitely a lot of ancient wisdom out there we
Speaker 2: haven't yet collected, and we can look forward to blowing
Speaker 2: the dust off of all of these.
Speaker 1: Secrets, but not too hard, because then you might destroy
Speaker 1: the dust.
Speaker 2: Right, only if you have supernova morning breath.
Speaker 1: All right, I guess the next time you look at
Speaker 1: into the nice guy, I know that you're looking at
Speaker 1: a bunch of dust as well, not just the beautiful
Speaker 1: twinkling stars.
Speaker 2: These tiny but mighty grains play an important role in
Speaker 2: the formation of the Solar system, in helping us understand
Speaker 2: what's out there, and also in blocking our view of
Speaker 2: part of the glorious cosmos.
Speaker 1: Hope you enjoyed that. Thanks for joining us. See you
Speaker 1: next time. Hey, it's hoar Hey from the podcast, and
Speaker 1: I'm super excited to announce that my new book, Oliver's
Speaker 1: Great Big Universe, is available to order now.
Speaker 2: Thanks for listening, and remember that Daniel and Jorge Explain
Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
Speaker 2: you listen to your favorite shows.