Speaker 1: Hey, Daniel, did you see that amazing volcano that erupted
Speaker 1: in Iceland? Is that the one in oh Nice? Is
Speaker 1: that how you say it in Icelandic? I don't actually
Speaker 1: speak Icelandic, though I do speak some Danish. Icelandic is
Speaker 1: more like old Norse. But Iceland, the country is super
Speaker 1: awesome and filled with volcanoes. Yeah, and there's one right now.
Speaker 1: It's spewing hot lava like as we speak. Yeah, it's
Speaker 1: like the Earth is breathing out more like burping or vomiting.
Speaker 1: The Earth got indigestion, I think I wonder how you
Speaker 1: say indigestion in Icelandic. It's just a volcano. I am
Speaker 1: more handmade cartoonists and the creator of PhD comics. Hi,
Speaker 1: I'm Daniel. I'm a particle physicist, and I'm substantially less
Speaker 1: gassy than the island of Iceland. Are you less gassy
Speaker 1: than the average physicists? No comment? Are you all full
Speaker 1: of I'm more full of hot area exactly. But welcome
Speaker 1: to our podcast. Daniel and Jorge Explained the Universe, a
Speaker 1: production of I Heart Radio in which we blow your
Speaker 1: mind into tiny, little hot pieces of gas by talking
Speaker 1: about all the crazy stuff that exists in our universe.
Speaker 1: We go way way back to the very beginning of
Speaker 1: the universe. Talk about how all that happened, how it
Speaker 1: led to this crazy, beautiful structure that we see today,
Speaker 1: and what progress we've made in unraveling that structure and
Speaker 1: understanding the fundamental nature of matter and space and time,
Speaker 1: and of course what the open questions are still. Yeah,
Speaker 1: we are here burping out amazing facts about the universe
Speaker 1: and expelling them out into the atmosphere for all of YouTube.
Speaker 1: Breathe in to your brains and absorb them and hopefully
Speaker 1: get nursed with some amazing pruce about the universe. That's right.
Speaker 1: We want these hot truth to roll over you like
Speaker 1: lava floating out a volcano. But you know, we're hoping
Speaker 1: not to burn you too much. Things are getting kind
Speaker 1: of hot, Dannie, I love it. I love it, and
Speaker 1: I love it, and who doesn't love lava. But yeah,
Speaker 1: it's a pretty big universe, and we are just this small,
Speaker 1: tiny little planet floating in the middle of mostly emptiness,
Speaker 1: careening through the space, ready to be hit by an
Speaker 1: asteroid perhaps. And this planet has a long and illustrious history.
Speaker 1: It hasn't looked the way it currently does for most
Speaker 1: of its life. We don't think of the Solar System
Speaker 1: and the galaxy is changing very much. They seems sort
Speaker 1: of static. But on a cosmological time scale, things are crazy,
Speaker 1: things are chaotic, things are changing all the time. Yeah,
Speaker 1: it's easy to think when you look out into the
Speaker 1: universe and to the stars that things are always the
Speaker 1: way they are right now. But no, actually, the universe
Speaker 1: is very dynamic, and it's changing, and it's constantly evolving,
Speaker 1: which tells us something important about what is gonna be like.
Speaker 1: If we want to know what the future Earth is
Speaker 1: going to be like and whether he means can still
Speaker 1: live on it, we better dig into its past and
Speaker 1: understand how it got to be such a warm and wonderful,
Speaker 1: cozy place to live. Yeah, what are we gonna be
Speaker 1: burping in a hundred million years perhaps or having indigestion
Speaker 1: with Yeah, So the Earth has an amazing history, and
Speaker 1: so one part of the Earth that's very important to
Speaker 1: us is its atmosphere. I count on it every day breathing.
Speaker 1: It fills me with life every single moment. Really, when
Speaker 1: you think about it, No, absolutely, we rely on it
Speaker 1: every single day. Well, we couldn't live without it. It
Speaker 1: feeds not just us, of course, but all the things
Speaker 1: that we eat drink. The atmosphere. It's a very complex
Speaker 1: and elaborate system of pumping gases out of plants and
Speaker 1: into plants and out of the ocean into the ocean.
Speaker 1: It's an amazing and complicated system, and it's incredible that
Speaker 1: it works at all, frankly, and then it's even at
Speaker 1: all stable. Thank goodness, we haven't because without an atmosphere,
Speaker 1: we wouldn't be here. We wouldn't just be out of
Speaker 1: breath and choke to death, but we would also be
Speaker 1: a pretty toasted thanks to all of the radiation coming
Speaker 1: from space. That's right, themospheres here. He keeps us warm
Speaker 1: and acts like a blanket and also acts like a
Speaker 1: shield protecting us from so many rocks and particles and
Speaker 1: all sorts of stuff coming from space. So it's a
Speaker 1: pretty important part of life here on Earth today and
Speaker 1: hopefully it'll stick around for another billion years or so. Yeah,
Speaker 1: and we should appreciate it because it wasn't always here
Speaker 1: on Earth. The Earth didn't always have an atmosphere. There
Speaker 1: was time and the history of Earth that we were
Speaker 1: basically naked right out in space nothing to drape over us.
Speaker 1: That's right. If you build a time machine and you
Speaker 1: want to see the early Earth, don't neglect to bring
Speaker 1: your space suit, because if you go back to three
Speaker 1: four billion years into Earth's history, you're not gonna be
Speaker 1: able to breathe whatever was on the Earth, if there
Speaker 1: even was anything. Yeah, and so a big question would
Speaker 1: be how did it get this way? How is it
Speaker 1: that we have this beautiful and fresh well depending on
Speaker 1: where you live, fresh air for us to take in
Speaker 1: and enjoy and live with. It's a fascinating story that
Speaker 1: dates way back to the very beginning of the Solar
Speaker 1: System and involves lots of dramatic pauses like volcanoes and
Speaker 1: the years and all sorts of other crazy stuff. So
Speaker 1: today on the podcast, we'll be asking the question where
Speaker 1: did the Earth get its atmosphere? Yeah? Where did it
Speaker 1: get its airs? Daniel? It's ambiance, that's right. And it's
Speaker 1: a very very fine place to hang out. It's very airy,
Speaker 1: it's very blue and transparent. I love what you've done
Speaker 1: with the place, really, Dole are burping apparently, I'm guessing
Speaker 1: maybe does that count as interior design if you're designing
Speaker 1: an entire planet or is it the still exterior design.
Speaker 1: I guess it depends. Are you like an alien shopping
Speaker 1: for planets? Are you like an earthling looking around? I'm
Speaker 1: imagining the aliens come, they take over the Earth, and
Speaker 1: they don't really like what we've done with the place,
Speaker 1: and they want to fix it up a little bit.
Speaker 1: So they hire some like massive geoengineering firm to do
Speaker 1: the equivalent of interior design, but for the whole planet.
Speaker 1: I wonder if that would be like a future career, like, hey, mom,
Speaker 1: I want to be a geo designer or a geodecorator.
Speaker 1: That's right, Mars has been using that same shade of
Speaker 1: red for like a billion years. It's time to pick
Speaker 1: a fresh color. How about cyan or a nice mango glaba.
Speaker 1: You need always three words in every name for a
Speaker 1: shade of paint, you know, wild Mountain, raspberry or something
Speaker 1: right that, so you can sell more of them, to
Speaker 1: be honest, because maybe you just sell red and blue,
Speaker 1: you're out of business. Well, if you're covering a whole planet,
Speaker 1: I think you're gonna sell a lot of gallons of paint.
Speaker 1: So yeah, So the Earth didn't always have the atmosphere
Speaker 1: that we're breathing right now. It used to be a
Speaker 1: pretty inhospitable place, right, that's right. It used to be
Speaker 1: a place where humans or animals could not survive because
Speaker 1: I guess initially, you know, we formed around a brand
Speaker 1: new Sun and we were just a bunch of rocks
Speaker 1: and gas kind of gathered together by gravity. Right. Yeah,
Speaker 1: everything in the whole Solar system, of course, came from
Speaker 1: the same big cloud of gas and dust to form
Speaker 1: the Sun and the planets and everything. But the story
Speaker 1: is a little bit more complicated. Yeah, So we were wondering,
Speaker 1: as usual, how many people out there know the story
Speaker 1: of our atmosphere and now how we got to have
Speaker 1: the air that we have. So, as usual, Daniel went
Speaker 1: out there into the wilds of the internet to ask
Speaker 1: people where did Earth get its atmosphere? And so, as usual,
Speaker 1: if you'd like to participate by answering funny questions with
Speaker 1: no preparation, please write to me two questions at Daniel
Speaker 1: and Jorge dot com. Trust me, it's fun. Here's what
Speaker 1: people had to say. I gotta guess from rocks during
Speaker 1: the heavy bombardment period when they guesses got released into
Speaker 1: the atmosphere. But the oxygen and atmosphere, which actually a
Speaker 1: lot higher today, came from I think it's Sanda bacteria,
Speaker 1: those rocks in Australia that the first thing is to
Speaker 1: photosymphasize and actually caused a huge distinction event um And
Speaker 1: the Earth was just formed. It was hot, and I
Speaker 1: think there were many chemical reactions going on away her
Speaker 1: atomic reactions and all. So maybe because of the reactions,
Speaker 1: I think probably they were just hydrogen and helium in
Speaker 1: the beginning, but then due to all these reactions, all
Speaker 1: the different gases will formed. Then maybe that's how we
Speaker 1: got that atmosphere. Let's say we have lots of nitrogen
Speaker 1: that prevents everything from blowing up. Then we have some
Speaker 1: oxygen and some argon. And that's about what I know
Speaker 1: about earth atmosphere. I can't really tell you where it
Speaker 1: comes from. I think the atmosphere came from volcanic activity
Speaker 1: when the Earth was young, and I know that the
Speaker 1: oxygen came from cyanobacteria producing it when life just got
Speaker 1: started on Earth. Well the proto or it was very
Speaker 1: very hot, so I would say that the burning and
Speaker 1: the temperature itself would cause gases to form that would
Speaker 1: accumulate around the Earth, being trapped in its gravitational field,
Speaker 1: and once the Earth cooled, the composition of the those
Speaker 1: gases must have changed, especially when life started to arise
Speaker 1: and would start to change the atmosphere and take out
Speaker 1: garbon dioxide and fill it with oxygen. I think they
Speaker 1: say Mars used to have an atmosphere. Maybe we stole
Speaker 1: mars atmosphere here have it on Earth now. Our atmosphere
Speaker 1: came from all the various eruptions on the Earth. In
Speaker 1: other words, the Earth's hot are the biggest contributor easy life.
Speaker 1: You fount organisms reciting the various chemicals from the atmosphere,
Speaker 1: apart from the atmosphere easily blanged by absorbing common trails
Speaker 1: and volcano emissions. I'm assuming, like ah, the formation of
Speaker 1: the Earth, there was a bunch of like dust and
Speaker 1: rocks and like just surrounding chemicals, and the Earth kind
Speaker 1: of lumped together. The rocks lumped together created kind of
Speaker 1: some strong gravity, and like particles and like air particles
Speaker 1: were like, hey, there's some gravity here. I guess let's
Speaker 1: like stick around, stick to it. And that's what happened. Alright.
Speaker 1: A lot of pretty detailed answers. You people have thoughts
Speaker 1: on the topic. Yeah, they have air, They have a
Speaker 1: lot of things to say about how we got our atmosphere.
Speaker 1: That's pretty cool. Do you think it's out there in
Speaker 1: the popular culture kind of the history of our atmosphere? Yeah?
Speaker 1: Or you know, maybe it's just so immediate people think
Speaker 1: about it. They literally breathe it in and out every day.
Speaker 1: So it's not some like weird, abstruse topic that only
Speaker 1: physicists wake up late at night thinking about. It's something
Speaker 1: everybody thinks about. And these days with all the discussion
Speaker 1: of global warming and climate change, it's something that people
Speaker 1: really do think about what's in the air and how
Speaker 1: we can influence it. And I guess it's kind of
Speaker 1: interesting that nobody was surprised. Nobody was like, what, we
Speaker 1: didn't always have an atmosphere? Like people seem to know
Speaker 1: that it came from somewhere. Yeah. Somebody even suggested we
Speaker 1: stole it from Mars. No way, what is it? Hot
Speaker 1: airror air? Hot exactly. They're gonna come looking for it,
Speaker 1: bring it pulled over with a vacuum and suck it
Speaker 1: all back up. So do you have a receipt for
Speaker 1: this atmosphere? I do. I just lost a seven billion
Speaker 1: years ago. Who keeps records that long anyway. Yeah, so
Speaker 1: it is an interesting story how we got our atmosphere,
Speaker 1: and so it's interesting to think that that wasn't always
Speaker 1: the case. You know, we were just a little barren
Speaker 1: rock floating out in space with some gas. Right. Yeah.
Speaker 1: It's really a fascinating story because the Earth has had
Speaker 1: different atmospheres through its history. Like if you took a
Speaker 1: time machine back to the very very early hot Earth,
Speaker 1: you'd experienced something very different from if you went back
Speaker 1: like three billion years ago or one billion years ago.
Speaker 1: So it's really it's a fascinating, very very dynamic story
Speaker 1: with lots of twists and turns. Yeah, and it's not
Speaker 1: just like a different temperature maybe, or like twists in
Speaker 1: the composition. It's like a totally different set of gas
Speaker 1: that was enveloping the Earth. Right, Yeah, we have like
Speaker 1: atmosphere three point oh these days we're not breathing the
Speaker 1: original atmosphere or even the second atmosphere. We're lacked on
Speaker 1: the third version of the atmosphere. It's been upgraded twice already. Well,
Speaker 1: do you think we got it this time or do
Speaker 1: you think we're do for an upgrade? I'm pretty happy
Speaker 1: with it. I got no notes like do we have
Speaker 1: to schedule the update? You know? Can we schedule it
Speaker 1: for like a billion years from now and when we're
Speaker 1: not around. Well that's the problem is sometimes you know,
Speaker 1: you're happy with your version of your operating system and
Speaker 1: then it updates itself and you're like, no, don't change anything.
Speaker 1: It was great. Do we have auto update on? Maybe
Speaker 1: we should turn that off because sometimes things don't work
Speaker 1: the same, you know, that's the solution of climate change.
Speaker 1: Rather just untake that box on the atmosphere operating system
Speaker 1: that says no updates please. All right, everybody stopped breathing
Speaker 1: for about a hundred years and then we'll get anyone.
Speaker 1: We're gonna reboot. Yeah, all right. Well, so you're saying
Speaker 1: this is not our first atmosphere. Um, we're in the
Speaker 1: third version. So what was the first version of the atmosphere?
Speaker 1: So the first version in the atmosphere formed when Earth
Speaker 1: formed itself. As we were saying before, everything in the
Speaker 1: Solar system came from the same basic constituents. You have
Speaker 1: this huge cloud of hydrogen mostly in a little helium
Speaker 1: and trace heavier elements, and that whole thing got sparked
Speaker 1: into a collapse, which led to the formation of the
Speaker 1: Sun of course, which is a huge ball of hydrogen.
Speaker 1: And then the planets gathered together and all basically came
Speaker 1: out of the same stuff, and you had planets formed
Speaker 1: because you had like little rocky cores that gathered together
Speaker 1: and gradually pulled other stuff along with it. And so
Speaker 1: what was Earth's atmosphere when it first formed, Well, the
Speaker 1: only gases around really were hydrogen and helium mostly, So
Speaker 1: just like Jupiter and the Sun and the other gas
Speaker 1: giants have big atmospheres mostly of hydrogen with a little
Speaker 1: bit of helium, Earth also had a helium hydrogen envelope
Speaker 1: around it when it first formed, right because I guess
Speaker 1: you know, the whole area in space was covered in
Speaker 1: hydrogen and helium and most of it went into the Sun,
Speaker 1: but I imagine some of it sort of hung out
Speaker 1: around the little rocky planets that were forming. Yeah, but
Speaker 1: not for very long. So what happens is these things
Speaker 1: are forming and they're collapsing, and there's sort of a race,
Speaker 1: Like the Sun is gobbling up a huge amount of
Speaker 1: this stuff, and the gas giants are out there, they're
Speaker 1: gobbling up a lot of it. And here in the
Speaker 1: inner Solar System, it turned out to be pretty hard
Speaker 1: to hold onto any gas because you're competing with the
Speaker 1: Sun that's slurping up all of the hydrogen as much
Speaker 1: as it can, and you don't have the gravity that
Speaker 1: like Jupiter has because the inner part of the Solar
Speaker 1: System is warmer, so there's no like rock ice to
Speaker 1: help you build a planet rapidly to grab some of
Speaker 1: that helium and that hydrogen. So out in the outer
Speaker 1: part of the Solar System where Jupiter was, you had
Speaker 1: rocks formed together but also with ice that let them
Speaker 1: see these larger planets that could hold onto their hydrogen.
Speaker 1: But here in the inner Solar System, Earth was just
Speaker 1: sort of like too small to really hang onto its hydrogen,
Speaker 1: so it was very short lived atmosphere. I guess maybe,
Speaker 1: like you know, lighter elements like hydrogen and helium, they
Speaker 1: get more easily sucked in by the Sun and other
Speaker 1: planets than the rocks that we have, right, that's kind
Speaker 1: of what happens is that you know, it's so light
Speaker 1: that they can just leave and get sucked in by
Speaker 1: the Sun. But whereas the rocks, it's harder for the
Speaker 1: Sun to have pulled us in that's exactly right. And
Speaker 1: there was also an opposite effect because once the Sun
Speaker 1: started burning, it was producing a solar wind, which is
Speaker 1: a huge amount of radiation that then blew off the
Speaker 1: rest of our atmosphere. Right, we had no magnetic field
Speaker 1: yet to protect ourselves from these things. Magnetic field is
Speaker 1: formed when layers inside the Earth are like mixing and
Speaker 1: blending and spinning. But the Earth was too young to
Speaker 1: have like differentiated and had these nicely divided layers that
Speaker 1: could produce a magnetic field. And so the solar radiation
Speaker 1: also blew off any gas that we did manage to grab.
Speaker 1: So initially we had a little bit of gas around
Speaker 1: our kind of brand new Earth, but then it quickly
Speaker 1: either left or it got blown away. Yeah, so this
Speaker 1: first atmosphere was very very short lived. I'm not even
Speaker 1: really sure you could say they was like settled down
Speaker 1: before it got slurped up by the Sun and then
Speaker 1: blown off by the solar radiation. Yeah. I feel like
Speaker 1: there's a lot of gas and wind in this story
Speaker 1: is getting a little um you know, gastric here, not
Speaker 1: just cosmic dig a tums. But there was a lot
Speaker 1: of stuff going on, like the early solar system was
Speaker 1: a very chaotic place, and it could have gone in
Speaker 1: lots of directions. You know, you could have had a
Speaker 1: planet here or a planet there. The reason we have
Speaker 1: a planet exactly here depends on a lot of very
Speaker 1: small chaotic factors that depended just on like the distribution
Speaker 1: of the initial stuff. But a little bit more clumpy
Speaker 1: or there, you would have got a different set of planets.
Speaker 1: All right, So then we had a little bit of
Speaker 1: hydrogen and helium, but then that quickly went away, and
Speaker 1: so what was our second atmosphere? So then the Earth
Speaker 1: was barren, right, we had just a ball of rock
Speaker 1: with really no atmosphere to speak of. Say this period
Speaker 1: here where the Earth is like naked. There's just no
Speaker 1: atmosphere protecting the surface of the Earth from basically space.
Speaker 1: And you know, interestingly, I talked to some geologists, and
Speaker 1: they don't see the Earth as naked in that sense.
Speaker 1: Like for them, the atmosphere is part of the crust.
Speaker 1: It's just like a different kind of crust, you know.
Speaker 1: They don't think of it as like the crust ends
Speaker 1: at the surface and then you have atmosphere. The atmosphere
Speaker 1: is just sort of like part of the crust. Because
Speaker 1: there's like constant interchange between the atmosphere and the surface,
Speaker 1: and it's just like you know, another layer of the earth. Sure,
Speaker 1: I guess two a geologist. They want it all, they
Speaker 1: want it all there like the air. That's part of
Speaker 1: my grant proposal as well. It's part of geology. Of course,
Speaker 1: humans where also geology. We are part of geology. Absolutely,
Speaker 1: we are part of the crust. And that's where this
Speaker 1: outer gas la or the crust that we call atmosphere
Speaker 1: came from when it was replenished. It was replenished from
Speaker 1: inside the Earth because volcanoes like the one in Iceland
Speaker 1: and the other ones around the Earth out gased like
Speaker 1: internal processes inside the Earth lead to these explosions and eruptions,
Speaker 1: which can produce enormous quantities of gas. Meaning like was
Speaker 1: all this gas forms inside of the Earth or it
Speaker 1: just got trapped as the Earth was sort of forming
Speaker 1: and all those rocks, actual rocks were coming together. Yeah,
Speaker 1: it's all in there, and it's all mixed together. You know,
Speaker 1: you have carbon, you have sulfur, as, you have oxygen.
Speaker 1: These are all the elemental ingredients of the Solar system,
Speaker 1: which are then compressed and mixed together. There's a lot
Speaker 1: of chemistry going on. So these elements all mixed together
Speaker 1: in the way that's like energetically most favorable. But then yeah,
Speaker 1: they get spewed up from underneath the earth, and you know,
Speaker 1: these rocks have gases dissolved in them sometimes and then
Speaker 1: those can come out when there's less pressure or I
Speaker 1: guess as maybe as things were sort of churning and
Speaker 1: coming up from the surface, then the gas was able
Speaker 1: to escape the rock. Exactly. Large gas bubbles exactly can
Speaker 1: make their way up through the crust and then emitted
Speaker 1: by the volcanoes. I mean, that's why volcanic eruptions happen, right.
Speaker 1: We talked about this in a recent episode on most
Speaker 1: massive volcanoes in the Solar System. When you have lava
Speaker 1: that has like a lot of silica dissolved into it,
Speaker 1: then it becomes like very sticky and it can absorb
Speaker 1: a lot of gas, and then the gas builds up
Speaker 1: the pressure and then it erupts and the gas can
Speaker 1: be freed. Right, And so that's how we got things
Speaker 1: like water of water, vapor and CO two and hydrogen
Speaker 1: open in the atmosphere. In that second atmosphere. Yeah, so
Speaker 1: the second atmosphere is mostly as you say, water, vapor,
Speaker 1: carbon dioxide, sulfur dioxide, and then a huge amount of
Speaker 1: just nitrogen. And very importantly, there was no free oxygen,
Speaker 1: no like O two molecules were floating around in the atmosphere.
Speaker 1: So this second atmosphere is not something we can breathe
Speaker 1: at all. It would be totally toxic. You took a
Speaker 1: time machine back to this volcanic period of the Earth
Speaker 1: and you took a deep breath as you stepped out,
Speaker 1: you would die pretty quickly. Great, not a great place
Speaker 1: to visit. No exactly what bring your space suit, you know,
Speaker 1: no big deal. Packs of oxygen. Just pack oxygen for
Speaker 1: fifty years. And there's one other source of sort of
Speaker 1: basic ingredients for our atmosphere. In those early days, it
Speaker 1: didn't just come from inside the Earth. There were some
Speaker 1: deposits from outside the Earth because during this period of
Speaker 1: chaos in the early Solar System, there's a lot of
Speaker 1: stuff moving around. The planets were switching positions and passing
Speaker 1: through the asteroid belt and passing through the asteroid belt
Speaker 1: in the other direction, which led to a lot of
Speaker 1: bombardment of the Earth by really big rocks. This is
Speaker 1: called the late heavy bombardment, and some of those rocks
Speaker 1: have water, and they have ice, they have other things
Speaker 1: frozen into them which then evaporated when they hit the Earth. Interesting,
Speaker 1: so those rocks had other sort of gaseous elements and
Speaker 1: then when they hit the Earth, they made it into
Speaker 1: our atmosphere. Yeah, just like we talked about how comets
Speaker 1: probably replenished the Earth's water in a very same way. Right,
Speaker 1: Earth had water when it formed, but then it boiled
Speaker 1: off because we our atmosphere is very hot surface, And
Speaker 1: we had a whole episode about how comics replenished the
Speaker 1: Earth's water in the same way. Asteroids and other things
Speaker 1: probably also replenished part of our atmosphere. Cool. All right,
Speaker 1: Well let's get into how we actually got breathable oxygen
Speaker 1: in our atmosphere and how we know all of these things.
Speaker 1: How do we know the history of our atmosphere? But
Speaker 1: first let's take a quick break. All right, we're talking
Speaker 1: about the history of air. Basically, right, where did air
Speaker 1: come from? And why is it so fresh to breathe? Yeah? Exactly,
Speaker 1: something it's all around us. It's something that we rely on,
Speaker 1: so we better understand why it's here and whether it's
Speaker 1: going away. Yeah. Do you think air is offended when
Speaker 1: we sneeze or like cough, like you know, get it
Speaker 1: out of my body? No, I think it's probably grateful.
Speaker 1: It's like, oh, that's much more interesting. Who wants to
Speaker 1: be inside of a wind warm human? All right, Well,
Speaker 1: we had one atmosphere, but then it was blown away
Speaker 1: by the sun and cosmic rays, and then we had
Speaker 1: got a second atmosphere that was burped up from the
Speaker 1: rock inside of the core of the Earth. And this
Speaker 1: atmosphere had a lot of oxygen, but it which just
Speaker 1: wasn't free oxygen like it was inside of C O
Speaker 1: two and H two O or s O two, but
Speaker 1: it was not something that we could use, like if
Speaker 1: we breathe it that you wouldn't be able to get
Speaker 1: that oxygen. Yeah, your lungs can't use that, right, even
Speaker 1: though there's oxygen c O two, if you step into
Speaker 1: a room that's pure CEO two, you're gonna fall unconscious
Speaker 1: pretty quickly. Yeah, not good. Alright, So then that's our
Speaker 1: second atmosphere. How do we get breathable oxygen? Then breathable
Speaker 1: oxygen came from life, right, This was terraformed by tiny, tiny,
Speaker 1: little microbes. But the first oxygen that was produced on
Speaker 1: Earth wasn't actually from those microbes. The very first came
Speaker 1: from ultra violet light that hit the Earth's atmosphere. When
Speaker 1: you v photons, these are just really high energy particles
Speaker 1: from the Sun and hit H two O molecules of water.
Speaker 1: They can break it up and you can get ozone
Speaker 1: formed in the atmosphere. And ozone is just a form
Speaker 1: of oxygen. It's an O three molecule and it forms
Speaker 1: in the upper atmosphere and it helps to actually shield
Speaker 1: us from ultra violet light. So ozone again not something
Speaker 1: you can breathe, but it's oxygen in the atmosphere which
Speaker 1: then shielded us from UV which helped life I think
Speaker 1: evolve a little bit interesting. So, like you just have
Speaker 1: water molecules H two os there and then when it
Speaker 1: gets hit by this light, it just breaks up, and
Speaker 1: I guess breaks up. But then the oxygen doesn't go
Speaker 1: into O two, it goes straight into OH three. Yeah.
Speaker 1: In these chemical processes, you always get a mixture of everything,
Speaker 1: but primarily this is how ozone is formed, and you
Speaker 1: also get some other stuff forming. You know, you get
Speaker 1: a little bit of O two but that's only responsible
Speaker 1: for like one per cent of the oxygen in the atmosphere.
Speaker 1: That's certainly not enough for us to breathe, all right,
Speaker 1: but it did sort of form enough O two then
Speaker 1: that you've kind of had to shield around Earth so
Speaker 1: that you could, you know, evolve little organism that did
Speaker 1: make well, it made O three, which is ozone, which
Speaker 1: is primarily the shield. But exactly it provides a shield
Speaker 1: to protect us from UV and that can like protect
Speaker 1: the DNA of delicate little critters as they're evolving on
Speaker 1: the Earth. All right. So then that's how we got
Speaker 1: most of our oxygen then, is through bacteria and things
Speaker 1: like that. Yeah, so bacteria have been around for quite
Speaker 1: a while, turning away in the oceans of the Earth,
Speaker 1: and at some point they evolved the ability to do photosynthesis, right,
Speaker 1: to take sunlight and to combine the energy from sunlight
Speaker 1: with C O two and water and to produce oxygen.
Speaker 1: And when this happens, they're essentially producing fuel for themselves.
Speaker 1: And so this is a really cool little thing that
Speaker 1: they evolved. It's called cyanobacteria that first evolved this ability
Speaker 1: to basically drink energy from the sun. And this started
Speaker 1: about two points seven billion years ago, and that's a
Speaker 1: very efficient way to turn c O two and H
Speaker 1: two O into oxygen us. Maybe the you know, in
Speaker 1: the primordial soup, you know, the earth was you know, inhospitable,
Speaker 1: but there were little tiny things that could grow in
Speaker 1: this environment in the oceans, and then that started turning
Speaker 1: out O two. But that wasn't very beneficial for them, right, No,
Speaker 1: it actually poisons them. Cyanobacteria are killed by the presence
Speaker 1: of O two, and so if they make too much
Speaker 1: of it, they kill themselves off. And again they don't
Speaker 1: need O too. It's like a byproduct. It's a waste
Speaker 1: product for them. But they wanted the CEO two, right.
Speaker 1: Plants breathe CEO two and produce oxygen. Animals like us
Speaker 1: breathe O two and produce c O two and cyanobacteria
Speaker 1: they're not plants. They're like the precursors of photosynthesis in plants.
Speaker 1: So they made a lot of oxygen, but that's not
Speaker 1: quite the oxygen we breathe today, right, that's right. The
Speaker 1: oxygen that was made by cyanobacteria originally didn't stick around
Speaker 1: in the atmosphere because oxygen is super duper reactive. It
Speaker 1: doesn't usually just hang out like if it can react
Speaker 1: with anything around it, it will. So you have this
Speaker 1: fresh earth covered in rocks, and these rocks are very
Speaker 1: reactive with oxygen. Like imagine a bunch of iron out
Speaker 1: there and you combine it with oxygen. When you get
Speaker 1: you get rust. And so basically most of the oxygen
Speaker 1: produced by the Earth and the first few hundred million
Speaker 1: years was then breathed in by the rocks on the Earth.
Speaker 1: They like sucked it all up. Wow, Like the Earth was,
Speaker 1: you know, shiny and nice looking, and then suddenly these
Speaker 1: bacteria breathed oxygen and everything rusted. Yeah, it was like
Speaker 1: hundreds of millions of years where the Earth was getting
Speaker 1: like a weatherized by all the oxygen that was being produced.
Speaker 1: And you know how you talk about like free radicals,
Speaker 1: etcetera in your body maybe causing damage and causing cancer.
Speaker 1: That's all because of oxygen. Oxygen is very reactive. It's
Speaker 1: like a crazy thing. It's going to touch and break
Speaker 1: things near it. And so that's what happened when cyanobacteria
Speaker 1: started pumping O two into the atmosphere, is that it's
Speaker 1: starting to get absorbed by all these rocks and break
Speaker 1: them down and weatherize them. And as you say, rust
Speaker 1: the entire planet. I guess that's a process that they
Speaker 1: had to happen, you know what I mean, Like, you
Speaker 1: can't just have like a shiny, brand new rust free
Speaker 1: Earth and also have oxygen. Like you're gonna put oxygen
Speaker 1: in the atmosphere, you have to first, you know, rust
Speaker 1: everything before you can breathe it. Yeah, everything is going
Speaker 1: to drink of that oxygen. So if you want enough
Speaker 1: floating around in the atmosphere for other things like animals
Speaker 1: to breathe, then you've got to sort of like fill
Speaker 1: up all the reservoirs out there that are just going
Speaker 1: to gobble the oxygen so that there's enough to float around.
Speaker 1: It's sort of like electrons and a semiconductor. You've got
Speaker 1: to fill up all the lower energy levels so you
Speaker 1: can have some floating around in the conduction band and
Speaker 1: conduct electricity. Right, That was the first analogy I was
Speaker 1: going to go with. I think these cyanobacteria are super amazing,
Speaker 1: and I love how plants basically co opted them because
Speaker 1: you know, the cyanobacteria, they evolved photosynthesis, and now when
Speaker 1: we look inside plants, we see these little objects inside
Speaker 1: a plant cell that can do the same thing, these chloroplasts.
Speaker 1: But those things are basically cyanobacteria. They got co opted
Speaker 1: by plants. The plants like eight them and said, okay,
Speaker 1: come do that work for me now. So the cyanobacteria
Speaker 1: should get all the credit for evolving this incredible ability
Speaker 1: to plants just to like took it over. They're like
Speaker 1: the managers. Or you could look at it the other way, right,
Speaker 1: you could say that cyanobacteria, you know, kind of form
Speaker 1: plants around themselves kind of to do all the hard work.
Speaker 1: They just have to sit back and get a plan. Exactly.
Speaker 1: You can look at anything in two ways, I guess.
Speaker 1: All right, So then we had to wait until everything
Speaker 1: was rusted before we got our third atmosphere. Yeah, it
Speaker 1: wasn't until everything was rusted that the oxygen being produced
Speaker 1: by cyanobacteria and then later also by plants could just
Speaker 1: sort of hang out in the atmosphere that those levels
Speaker 1: could climb to the point where like animals could breathe them.
Speaker 1: And so now we're up to the atmosphere that we
Speaker 1: have today, which is you know, still mostly nitrogen. It's
Speaker 1: like seventy eight percent nitrogen, but a good of our
Speaker 1: atmosphere is O two wow. And it was all made
Speaker 1: by bacteria and plant basically right like before and like
Speaker 1: you know, we didn't get that we made that. Yeah,
Speaker 1: it was made by living creatures. And it took a
Speaker 1: long long time. Right, So if you're imagining, like let's
Speaker 1: go to Mars and produce enough oxygen for the atmosphere
Speaker 1: for us to walk around and breathe, like, it takes
Speaker 1: a long time. Even when you got like jillions of
Speaker 1: tiny little machines pumping out of oxygen, it took millions
Speaker 1: and millions of years. Yeah, it took like four hundred
Speaker 1: million years actually to be precise. And in a way,
Speaker 1: they sort of ruined the planet for themselves a little bit, right,
Speaker 1: or do you think they were co evolving as they
Speaker 1: were changing the atmosphere. They're definitely co evolving. And cyanobacteria
Speaker 1: are still with us. They still produce half of the
Speaker 1: oxygen that we have on the Earth currently, like half
Speaker 1: of it is made by plants and half of it
Speaker 1: is made by cyanobacteria. So they're still around in the oceans. Yeah,
Speaker 1: And so that's how we got our atmosphere and it's
Speaker 1: not I mean it's a lot, obviously, because we have
Speaker 1: a lot to breathe, but in terms of the scale
Speaker 1: of the Earth, it's a really small fliver or a
Speaker 1: small coating of air that we have on the planet. Yeah.
Speaker 1: The whole Earth, of course, is six thousand kilometers in radius.
Speaker 1: The atmosphere where we considerately the atmosphere is you know,
Speaker 1: just like thirty or fifty kilometers high, so it's a
Speaker 1: very very thin ver near It's like a very thin
Speaker 1: coating of water on a billiard ball. Yeah, because like
Speaker 1: what the Earth is, what like ten thousand kilometers in
Speaker 1: radius or something like that kilometers in radius, but only
Speaker 1: the last thirty kilometers are atmosphere. Yeah, And where exactly
Speaker 1: you say the atmosphere and depends really just on where
Speaker 1: you want to say it ends. Some people say it's
Speaker 1: up to a hundred kilometers because you know, it falls
Speaker 1: off very smoothly as you go out into space. But
Speaker 1: of the mass of the atmosphere, like most of the
Speaker 1: stuff in the atmosphere is within the first thirty kilometers.
Speaker 1: The geologists also claim space as geology as well. They're like,
Speaker 1: you know, I just keep going. Their atmosphere is geology,
Speaker 1: space is geology. Galaxies geology. When they say we are
Speaker 1: one with the universe, they mean it literally, like the
Speaker 1: universe is just all part of the Earth. We are one,
Speaker 1: and that one is you got below the surface and
Speaker 1: above the surface, and it's just two parts to the
Speaker 1: whole universe. Or no, it's it's all one big surface geologist.
Speaker 1: But it's actually quite interesting. There are lots of like
Speaker 1: really fascinating layers to the atmosphere. Like you might imagine
Speaker 1: as you go higher up, the air gets thinner and
Speaker 1: thinner and colder and colder until you get out into
Speaker 1: space and it's like super freezing. But actually the temperature
Speaker 1: like varies and it gets hotter and colder and hotter
Speaker 1: and colder as you go up really depending on like
Speaker 1: the composition or did you just get like pockets of stuff, Yeah,
Speaker 1: depending on the composition. They're all these fascinating layers. Like
Speaker 1: as you go up, you know, you go above like
Speaker 1: Mount Everest, for example, things get colder and colder and
Speaker 1: thinner and thinner. But then when you get to like
Speaker 1: this ozone layer, things turn around and start to get hotter.
Speaker 1: As you go past the stratosphere, things actually start to
Speaker 1: get hotter and hotter and hotter, not quite back up
Speaker 1: to like surface levels, but you know, getting kind of
Speaker 1: warm before they turn around again and then get colder
Speaker 1: as you go up through the is a sphere and
Speaker 1: then it turns around again and it actually gets hotter
Speaker 1: and hotter as you go into space, right, Yeah, because
Speaker 1: I guess those are the layers that are absorbing a
Speaker 1: lot of the sunlight. Is that what's happening. They are
Speaker 1: absorbing a lot of the sunlight and they are evaporating, Right,
Speaker 1: what's going to be leaving the Earth? What's going to
Speaker 1: be making it out there to the higher levels are
Speaker 1: the faster moving particles, and so the Earth is sort
Speaker 1: of like differentiating. We are losing our atmosphere constantly. We
Speaker 1: had a whole podcast about that, and primarily we lose
Speaker 1: the hotter atoms, the faster moving ones. So while it's
Speaker 1: not very dense up there, there's not a lot of heat,
Speaker 1: you have faster moving particles, which are the ones that
Speaker 1: are escaping, and so it technically it is hotter. Yeah,
Speaker 1: the hotter ones that are always the first ones to leave,
Speaker 1: for sure. And there's also sort of like radioactive elements
Speaker 1: out there in our atmosphere too, right, Like some pretty
Speaker 1: not saying stuff out there. Yeah, absolutely, one percent of
Speaker 1: our atmosphere is actually are gone. You know, You've got
Speaker 1: like seventy percent nitrogen oxygen, and then one percent are gone,
Speaker 1: which is sort of weird. It's this radiogenic argon forty
Speaker 1: which comes from the decay of potassium forty. And it's
Speaker 1: really interesting actually, because mostly which you have out there
Speaker 1: in the universe, like made by stars is aregon thirty six,
Speaker 1: which is, you know, a different isotope of argon that's
Speaker 1: made in the fusion inside stars. But here on Earth,
Speaker 1: most of the argon in our atmosphere is argon forty,
Speaker 1: which comes from this radioactive decay. And it took people
Speaker 1: a long time to figure out that that's where it
Speaker 1: came from and how it worked, and it was a
Speaker 1: fun puzzle that was solved a few decades ago. And
Speaker 1: there's also some pretty interesting elements like krypton and neon
Speaker 1: and methane, And our atmosphere is not just like nitrogen
Speaker 1: and air and oxygen. Do you remember that everything in
Speaker 1: our solar system came from those same basic soup of ingredients.
Speaker 1: Inside the Sun, of course you have fusion making new
Speaker 1: heavy elements, but outside of the Sun, everything is just
Speaker 1: a mixture of the same elements that went in. Right,
Speaker 1: we have no fusion happening on Earth. All the elemental
Speaker 1: like crypton or neon, or hydrogen or oxygen or all
Speaker 1: the other weird stuff that we have came from fusion
Speaker 1: in side some star somewhere else. Our solar system is
Speaker 1: a population one solar system, which is the third generation
Speaker 1: in our universe. So all of these atoms of oxygen
Speaker 1: and other stuff were formed inside a star billions of
Speaker 1: years ago, which then blew up and led to the
Speaker 1: formation of this dust cloud, which eventually became our solar system.
Speaker 1: That means we're all a little bit cryptonian, right, a
Speaker 1: little bit. Yeah. All of these things that were made
Speaker 1: of that we're breathing, that we're relying on, all came
Speaker 1: from somewhere else, were fused inside a star somewhere, and
Speaker 1: so that's how we got our atmosphere through a lot
Speaker 1: of burpaying by the Earth and surviving some winds and
Speaker 1: a lot of bacteria making it. And that's how we
Speaker 1: got the air that we have today. And thank goodness,
Speaker 1: because it smells pretty good. You could have smelled that, right,
Speaker 1: you guys. We're lucky that the Earth smells good. It
Speaker 1: probably did smell pretty bad for long periods. You know,
Speaker 1: they're probably some pretty stinky times when Earth the stinker scene,
Speaker 1: I think it's called, you know, teenagers they never smelled,
Speaker 1: Introduce them to deodorant, and then things pick up from there.
Speaker 1: All right, let's get into how we know this interesting
Speaker 1: history of our atmosphere and what it could mean for
Speaker 1: the future of Earth and people breathing in it. But first,
Speaker 1: let's take another quick break. All right, we're talking about
Speaker 1: the history of our atmosphere and we're kind of in
Speaker 1: our third atmosphere, is what you're saying, Like we you know,
Speaker 1: we're not in our starter home, we're not in our
Speaker 1: second home. We're like in our our vacation home. Unless
Speaker 1: we've been working on this for a while. We're living
Speaker 1: the dream right now, breathing the dream. We are we
Speaker 1: are And I love hearing those kinds of stories when
Speaker 1: you look around and you don't really know what the
Speaker 1: history of the Earth is, and then you discover through
Speaker 1: various like really subtle clues and awesome detective work that
Speaker 1: things have changed, that the Earth used to be really
Speaker 1: really different. Because you know, your naive assumption is like
Speaker 1: I don't know the earth form that had it to
Speaker 1: have spirits always been like this, that's the simplest story,
Speaker 1: and science always prefers the simplest story. But it's super
Speaker 1: fun when you discover that the story is more complicated
Speaker 1: than it has twists and turns. But you can't just
Speaker 1: like tell that story. You gotta find the clues. You've
Speaker 1: got to discover that story. Yeah, because that's a big question.
Speaker 1: It's like, how do we know all these details? I
Speaker 1: feel like that was a very detailed story of how
Speaker 1: we got our atmosphere, but there was nobody around really
Speaker 1: to sort of measure the oxygen or to see what
Speaker 1: was happening. So how do we know all of these things? Yeah,
Speaker 1: we have to look for clues in the geological record,
Speaker 1: and so the rock record, like rocks that were formed
Speaker 1: five hundred million years ago or a billion years ago
Speaker 1: or two billion years ago, how they formed, and which
Speaker 1: kinds of rocks formed tell us about what atmosphere there
Speaker 1: was around, because some kind of rocks can only form
Speaker 1: in the presence of oxygen, and other kind of rocks
Speaker 1: can only form if there's no oxygen. So as you
Speaker 1: look at the rock layers, you can look like back
Speaker 1: in time and get a sense for like what was
Speaker 1: going on, right, because I guess the rocks are stead
Speaker 1: of changing, right, they're churning, they're flipping over. They sort
Speaker 1: of build up as they're growing, right, So then then
Speaker 1: that's where you get the record. Yeah, if you drive
Speaker 1: through the desert, for example, and you see canyons, etcetera,
Speaker 1: you can see these stripes in the rocks. Right, where
Speaker 1: do those stripes come from? Those are layers of rocks
Speaker 1: that have been laid down over millions and billions of years.
Speaker 1: As you say, the surface is like active stuff is
Speaker 1: coming out from underneath and then creating new layers which
Speaker 1: get laid down and then pushed down, and sometimes those
Speaker 1: layers then break and get pushed back up to the
Speaker 1: surface and revealed, and so we can see that history.
Speaker 1: That's why like dinosaurs are buried in the earth, because
Speaker 1: we're constantly laying down new layers of rock on top
Speaker 1: of the old ones. And so that's super cool because
Speaker 1: it's basically like a snapshot of what was going on
Speaker 1: on the planet back in the day. And as you
Speaker 1: can look at those rocks and see patterns in them,
Speaker 1: then you can get a clue is to like what
Speaker 1: was going on in the atmosphere because all those rocks,
Speaker 1: as we were saying before, interacted with the atmosphere that
Speaker 1: leaves an imprint on the rock basically like if they
Speaker 1: was a lot of oxygen or not, or other kinds
Speaker 1: of gases than the rocks a little different. Yeah, And
Speaker 1: one of the most important clues are these formations called
Speaker 1: banded iron. And these are really beautiful. You should google
Speaker 1: them and check them out because they are basically these
Speaker 1: rocks with these thick red stripes in them, this oxidized
Speaker 1: iron stripes, And that tells us a lot about when
Speaker 1: this oxygen nation event happened, when the cyanobacteria started pumping
Speaker 1: oxygen into the atmosphere, because it started to bind with
Speaker 1: the iron that was out there and get weatherized and
Speaker 1: make these layers and layers of basically rushed inside the
Speaker 1: Earth's atmosphere. So you can look back at these first
Speaker 1: earliest layers of rust and pinpoint when oxygen starts to
Speaker 1: be produced. That makes me think of like a heavy
Speaker 1: metal band or something bad. Iron first rust. There you go,
Speaker 1: red rusted rage. It's super cool because it's sort of
Speaker 1: like rings on a tree because you can see these bands.
Speaker 1: It's not just like, oh, oxygen turned on, start to
Speaker 1: be produced, and then everything after that is just rusted iron.
Speaker 1: You have these bands where it's like rusted iron and
Speaker 1: then none, and then rusted iron and then none, like
Speaker 1: turned on and off and on and off. You can
Speaker 1: be like, oh, look at the earth just burped here
Speaker 1: or just past wind. Yeah, what happens is that this
Speaker 1: oxygen that these bacteria produced is actually poisonous to them, right.
Speaker 1: Cyanobacteria do not like a lot of oxygen, so they
Speaker 1: produced a bunch of oxygen and some cases there was
Speaker 1: like a lot of iron around in the water to
Speaker 1: grab that oxygen and then sink back down to the
Speaker 1: ocean floor and form a band. But sometimes the cyanobacteria
Speaker 1: would produce too much oxygen it couldn't all get breathed
Speaker 1: in by this iron, and then they would poison themselves
Speaker 1: and like kill themselves off, and then they wouldn't be
Speaker 1: producing as much anymore, and so there wouldn't be as
Speaker 1: much iron deposited. But then the conditions were favorable again
Speaker 1: for a cyanobacteria, which would then grow back and produce
Speaker 1: a huge amount of oxygen, which would they create another
Speaker 1: band and sort of this sort of cycle effect where
Speaker 1: they overproduced and kill themselves and then grow. That's kind
Speaker 1: of what's happening to us right now. I mean, we
Speaker 1: are creating so much c O two. Every time we
Speaker 1: breathe out, we create c O two, And so we
Speaker 1: didn't have all these other processes to repleashes the O two,
Speaker 1: we would be basically poisoning ourselves, right, breathing ourselves out
Speaker 1: of a planet. Yeah, we could have a sort of
Speaker 1: similar effect we have, like human civilization builds up and
Speaker 1: then poisons itself with c O two, and then you
Speaker 1: have like a com period on the Earth for a
Speaker 1: million years, while you have like small bands of humanity surviving,
Speaker 1: rebuilding civilization to poison ourselves. Again. I can see your
Speaker 1: brain just writing the sci fi novel there. I think
Speaker 1: I've read that one. But I guess maybe a question
Speaker 1: is like, how do we, you know, correlate that to time.
Speaker 1: Like we can see these bands in the rock, but
Speaker 1: how do we know that band took place or was formed,
Speaker 1: you know, three hundred million years ago or six billion
Speaker 1: years ago? How do we get that calibration of the
Speaker 1: rings in the tree? Oh yeah, great question. It's like
Speaker 1: how do we know the age of any rock? You know?
Speaker 1: And I remember thinking about this as a kid, wondering,
Speaker 1: like what does it even mean the age of a rock?
Speaker 1: You know, because like love is lava, rock and melt
Speaker 1: or flow. It's like asking how old water is. But
Speaker 1: when you talk about the age of a rock, you're
Speaker 1: not talking about like when the chemical elements or even
Speaker 1: the elements inside the rock were formed, because that happened
Speaker 1: inside a star billions of years ago. We're talking about
Speaker 1: like when this crystal was created. Because rocks are a
Speaker 1: solid formation of these elements, right, like cooled together to
Speaker 1: form a solid object. So you can measure that age
Speaker 1: of the rock, which is when did this thing become
Speaker 1: a solid object? How long ago was this thing fluid?
Speaker 1: When did it transition to becoming solid? And you can
Speaker 1: measure that because when that happens, it captures things inside
Speaker 1: of it, these crazy little crystals, and those crystals, some
Speaker 1: of them are radioactive and they like decay very slowly
Speaker 1: over time. You can measure how many of those are
Speaker 1: and calibrate them. And that's when you do to measure
Speaker 1: the age of rocks. I see, like when the rock forms,
Speaker 1: they capture like a taking clock almost inside of them.
Speaker 1: It's sort of similar to carbon dating, which we can
Speaker 1: use to age like things that were once alive because
Speaker 1: they have certain ratios of carbon in them. But here
Speaker 1: we're talking about things that are much much older. So
Speaker 1: we use these radiometric dating methods based on the natural
Speaker 1: radioactive decay of things like potassium and carbon to date
Speaker 1: these ancient ancient events. I would different rocks. That's a
Speaker 1: terrible joke. I apologist for them. So yeah, so that's
Speaker 1: how we know then, how the history of our atmosphere. Yeah,
Speaker 1: because we can look at this record and so that's
Speaker 1: one piece of evidence is these banded iron formations. You
Speaker 1: know this that's a big influence on like our civilization
Speaker 1: because Detroit, for example, is in a location where there
Speaker 1: used to be an ocean with huge colonies of cyanobacteria
Speaker 1: depositing lots of bands of iron and so like that's
Speaker 1: why a huge fraction of the steel deposits available on
Speaker 1: Earth are like near Detroit, and that's why we have
Speaker 1: a car industry near Detroit because of this cyanobacteria. So
Speaker 1: I love these like connections from the ancient times back
Speaker 1: to like you know, modern zivilization and even politics. They
Speaker 1: always talk about the rust belt, right exactly, they should
Speaker 1: be talking about the cyanobacteria belt. Really, yeah, nobody wants
Speaker 1: to be in that political group. But this also lines
Speaker 1: up with other pieces of evidence. Again, we look into
Speaker 1: the record to see what could happen with oxygen and
Speaker 1: what could happen without oxygen. And there are other minerals
Speaker 1: like pyrite, this thing called fools gold, which can only
Speaker 1: form when there's no oxygen in the atmosphere. It's it's
Speaker 1: oxygen around and the elements that would otherwise make pyrite
Speaker 1: tend to make other things instead. And so you can say, like, oh,
Speaker 1: pyrite was only created until about a certain date several
Speaker 1: billion years ago. So that's another clue. And I imagine
Speaker 1: also there's a lot of it is sort of theoretical,
Speaker 1: kind of based on models of how the Earth form, right,
Speaker 1: for example, we can only go back so much. But
Speaker 1: these methods, like when you're talking about before, like you know,
Speaker 1: our early or first atmosphere getting blown away by the
Speaker 1: solar wind. That's you know, we don't have evidence for that,
Speaker 1: but you know, from what we know how the planets
Speaker 1: get formed, that's probably what happened and we know the
Speaker 1: solar wind exists. We can measure the solar wind, and
Speaker 1: so we can model what would happen if we didn't
Speaker 1: have a magnetic field. So yeah, well there's a lot
Speaker 1: of things we can do to validate those models. But
Speaker 1: absolutely there's modeling going on all over the place in
Speaker 1: all of these studies. And you know, we try to
Speaker 1: make assumptions and then they would trying to find ways
Speaker 1: to check them and to validate those assumptions. Absolutely. You know,
Speaker 1: another thing we do is we think about, like how
Speaker 1: life could have evolved. A lot of the basic chemical
Speaker 1: building blocks of life couldn't have formed if we had
Speaker 1: oxygen in the atmosphere, right, So life produced oxygen, but
Speaker 1: in lots of cases it's inhibited by the presence of oxygen.
Speaker 1: That kind of life that me and you are, this
Speaker 1: aerobic kind of life that relies on oxygen, is fairly
Speaker 1: late showing up in the evolutionary record. And so if
Speaker 1: we had had oxygen, like outgassed by those volcanoes, we
Speaker 1: might not have formed life, right because the earliest life,
Speaker 1: like our ancestors, were anaerobic, right, they didn't like oxygen. Yeah,
Speaker 1: they're poisoned by oxygen, and not just the life itself,
Speaker 1: like the chemical building blocks, a lot of those amino
Speaker 1: acids that they need to just like bump together in
Speaker 1: a weird way in the primordial soup. Those couldn't have
Speaker 1: formed if there was oxygen, because oxygen is just like
Speaker 1: so excited. It bonds to everything and it prevents other
Speaker 1: things from happening. So if we've had oxygen around, we
Speaker 1: could have made those building blocks, and maybe life itself
Speaker 1: wouldn't have started sort of crazy. So it's a good
Speaker 1: thing we didn't have oxygen then, but it's a good
Speaker 1: thing that we have it now, Yes, exactly. And it's
Speaker 1: like such a delicate balance, right. We needed oxygen to
Speaker 1: not be around, and then we needed these other life
Speaker 1: to exist for a while, and then to produce a
Speaker 1: bunch of oxygen so that we could evolve. It's a
Speaker 1: crazy story, right, but I guess it's all one constant evolution. Right.
Speaker 1: You can't just ask, like, we wouldn't be here if
Speaker 1: we didn't have oxygen, but maybe some other anaerobic beans
Speaker 1: would be here having a podcast breathing out less hot
Speaker 1: air than we are, at least less mellie air. Maybe. Yeah, absolutely,
Speaker 1: it's just that our particular path relied on all of
Speaker 1: these things happened in a particular order. Really, if things
Speaker 1: have been different, you know, you could have evolved life
Speaker 1: in lots of other different ways. Well, I guess I'm
Speaker 1: glad that it worked out this way. And it's good
Speaker 1: to know these things also because not just because maybe
Speaker 1: we want to change other planets, but we may also
Speaker 1: want to find other planets like ours that have an atmosphere,
Speaker 1: and so knowing these things might help us find or
Speaker 1: maybe our second or fourth home or retirement home maybe
Speaker 1: for humanity. Yeah, we are just now able to probe
Speaker 1: the atmospheres of planets around other stars by seeing how
Speaker 1: light passes through them as they block their stars. And
Speaker 1: understanding how a planet forms its atmosphere and how the
Speaker 1: atmosphere evolves is really crucial to answering the question like
Speaker 1: is there one out there we could land on? Because
Speaker 1: there might be a planet out there in the habitable zone,
Speaker 1: meaning it's like warm enough to melt water on the surface,
Speaker 1: but there might not be an atmosphere, and that's not
Speaker 1: terribly useful because you can take millions and millions of years.
Speaker 1: Even if you like plants cyanobacteria in the water on
Speaker 1: an alien planet to produce enough oxygen. So it's a
Speaker 1: really interesting question, like how long does this take? Is
Speaker 1: it unusual on Earth? Could happen faster on other planets?
Speaker 1: Is it already happening on other planets out there right
Speaker 1: now with primitive life producing oxygen. It's a really interesting
Speaker 1: and deep question and one that might be really important
Speaker 1: for the future of humanity. Yeah, you don't want to
Speaker 1: pack up all of your things move halfway across the
Speaker 1: gaxy and then when you get there, that wouldn't be good.
Speaker 1: And also for our neighbors. You know, Elon Musk talks
Speaker 1: a lot about moving to Mars and making it a
Speaker 1: second home for humanity, but it's going to take a
Speaker 1: long time before you can walk on the surface of
Speaker 1: Mars and like take a deep breath and survive, not
Speaker 1: to mention even enjoy it. All right, Well, it kind
Speaker 1: of makes you grateful for the air that we have,
Speaker 1: because you know, this is kind of the only thing
Speaker 1: we have to breathe and the only place in our
Speaker 1: Solar System and maybe in our galaxy that we know
Speaker 1: of right now where we could comfortably walk around outside
Speaker 1: and breathe the air. I'm very grateful. I'm full of it.
Speaker 1: You're full of hot air and cold air and all
Speaker 1: the air. I'm putting them all on at the same time,
Speaker 1: and burping them and doing other contributions to the air
Speaker 1: all at the same time, and speaking Icelandic very badly
Speaker 1: into a microphone for other people to hear. All right, Well,
Speaker 1: that's the history of our atmosphere and we hope you
Speaker 1: enjoyed that. Thanks for joining us, See you next time.
Speaker 1: Thanks for listening, and remember that Daniel and Jorge explained.
Speaker 1: The Universe is a production of I Heart Radio or
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