Speaker 1: Hey, Orge, are you preparing your kids for when the
Speaker 1: end times come?
Speaker 2: Oh?
Speaker 3: You mean when bananas go extinct? Or do you mean
Speaker 3: when I retire?
Speaker 1: Yeah, I mean the fall of civilization, when we're all
Speaker 1: listening to podcast in our caves.
Speaker 3: I feel like I've been preparing my whole life. If
Speaker 3: there's a post apocalyptic movie out there, I probably see it.
Speaker 1: Well, then I hope you're teaching your kids some useful skills,
Speaker 1: you know, blacksmithing, martial arts, cartooning.
Speaker 3: Oh yeah, cartooning for sure, that's going to come in handy.
Speaker 3: But you don't think they should learn a particle physics.
Speaker 1: I don't know that anybody's going to be building colliders
Speaker 1: out of sticks and rocks.
Speaker 3: Isn't it fire? Doesn't it fire evolve particles colliding?
Speaker 1: A fire is kind of a chemical accelerator. I suppose
Speaker 1: there must be some collisions, or.
Speaker 3: Are you going to be like, you know, freezing out there,
Speaker 3: and you're gonna be like, oh no, no, sorry, the
Speaker 3: fire is just not fundamental.
Speaker 1: Enough for me. I think I would be hiding in
Speaker 1: my cave eating the last of the world's chocolate reserves.
Speaker 3: Who would that be a useful skill? You could be
Speaker 3: it the world's only chocolate tear. Hopefully the zombies like chocolate.
Speaker 1: Dark chocolate is the world's final currency.
Speaker 3: I am Poorge, my corctoonist and the author of Oliver's
Speaker 3: Great Big Universe.
Speaker 1: Hi, I'm Daniel. I'm a particle physicist and a professor
Speaker 1: at UC Irvine, and I purposely got into particle physics
Speaker 1: because it was useless.
Speaker 3: You're like, how can I make my time here on
Speaker 3: Earth less useful?
Speaker 1: I wasn't so much worried about the positive practical benefits
Speaker 1: as the negative. You know, my parents worked in the
Speaker 1: weapons programs, and I really really didn't want to do
Speaker 1: anything that could be used as the basis of a
Speaker 1: death ray.
Speaker 3: I see, But you could have picked something positively useful,
Speaker 3: like making a chocolate Yeah, there you go, making people happy.
Speaker 1: Well, you know, my dad did retire from the lab
Speaker 1: and then became a blacksmith, so he's definitely got useful
Speaker 1: skills for the end times.
Speaker 3: He became a blacksmith. Wow, was he forging like swords
Speaker 3: or internal combustion engines in your garage?
Speaker 1: Or what swords? Spears? All kinds of stuff?
Speaker 3: Yes, He's like, I want to wait more weapons.
Speaker 1: I wish I were joking more and.
Speaker 3: More direct, but anyways, Welcome to our podcast. Daniel and
Speaker 3: Jorge Explain the Universe, a production of iHeartRadio.
Speaker 1: In which our only weapon is our minds. As we
Speaker 1: tackle the quest of understanding the universe, we go forging
Speaker 1: through all of the craziness that's out there and try
Speaker 1: to weave it all together into an explanation that makes sense.
Speaker 1: We hope that whatever the universe is made out of
Speaker 1: its time, any little basic bits that somehow they're danced
Speaker 1: together can explain everything that we experience in the universe,
Speaker 1: that we can somehow find fundamental laws, and then we
Speaker 1: can also make sense of it all that's right.
Speaker 3: We try to hone our knowledge of signs here and
Speaker 3: try to prepare you for the end times when we'll
Speaker 3: all be looking up at the stars wondering how do
Speaker 3: we all get here? And how do we avoid those
Speaker 3: pesky zombies.
Speaker 1: I guess we should all try to sharpen our minds
Speaker 1: so we can slice our way through these problems.
Speaker 3: Yeah, I'm sure having physics knowledge will be helpful in
Speaker 3: the apocalypse, right, you can, I guess, try to build
Speaker 3: a laser gun to fight the zombies.
Speaker 1: If the zombies assigned a lot of homework problems, then
Speaker 1: I'm definitely there to help.
Speaker 3: Oh, that could be another way to defeat them. You know,
Speaker 3: you give them physics problems that are so tricky that
Speaker 3: their brains explode, and that everyone knows that's how you
Speaker 3: kill zombies.
Speaker 1: Wow. Yes, exactly. Too many into girls.
Speaker 3: Calculus.
Speaker 1: No, you know, Newton definitely believed in zombies. Really, Newton
Speaker 1: definitely believed in some weird stuff. I don't know about zombies,
Speaker 1: but you know, he was an alchemist and he definitely
Speaker 1: was a fan of the arcane.
Speaker 3: Wasn't he really into currencies too?
Speaker 1: Mm hmmm, yeah, exactly.
Speaker 3: At some point became like a coin master or something.
Speaker 1: He was definitely a weird dude.
Speaker 3: Yes, by word, do you mean a genius who basically
Speaker 3: invented science.
Speaker 1: I think that's actually giving him a little bit too
Speaker 1: much credit. But yeah, he invented lots of physics and
Speaker 1: big chunks of math, and I think he would be
Speaker 1: pretty tickled if we could use calculus against the zombies.
Speaker 3: Oh well, I'm sure a lot of people will be
Speaker 3: relieved to learn it's useful for something after all that
Speaker 3: work in high school.
Speaker 1: Yeah, they can integrate it into their lives.
Speaker 3: Oh boy, that was very terrifical joke. But anyways, we
Speaker 3: do like to think about the universe and we try
Speaker 3: to explain it here on the podcast, and sometimes that
Speaker 3: involves answering questions.
Speaker 1: That's right. It's not just Isaac Newton who's thinking about
Speaker 1: the nature of the universe. It's everybody. The goal of
Speaker 1: science is to understand the universe, and that means for
Speaker 1: everybody to figure it out. And that, of course means
Speaker 1: everybody's got to be out there thinking about the universe,
Speaker 1: asking questions, wondering how it all works, and we want
Speaker 1: you to be doing that. We hope that this podcast
Speaker 1: stimulates your curiosity. You hear on the podcast about the
Speaker 1: questions we are asking, but we want to hear about
Speaker 1: the questions you are asking, and then we want to
Speaker 1: answer them. So if you have questions about the nature
Speaker 1: of the universe or something you heard about on the podcast,
Speaker 1: or something you heard about on Gass another podcast, please
Speaker 1: write to me to questions at Danielanjorge dot com. We'll
Speaker 1: clear it up for you.
Speaker 3: Yeah, because it's part of human nature to be asking questions,
Speaker 3: and it's totally fun to ask questions as well, and
Speaker 3: so here in the podcast we sometimes like to answer
Speaker 3: questions that listeners send us, and so to be on
Speaker 3: the podcast, we'll be tackling listener questions number sixty six.
Speaker 1: You have a sixty six related snide comment.
Speaker 3: Only a warning, Daniel. If we keep going, we're going
Speaker 3: to hit listener questions six sixty six.
Speaker 1: Oh, I thought you were going to warn me. But
Speaker 1: listener question sixty nine, where we turn everything upside down.
Speaker 3: I have warned you repeatedly about that milestone, and you
Speaker 3: don't seem very concerned.
Speaker 1: I'm mindlessly barreling towards it.
Speaker 3: Well, just maybe we'll record it, but then we'll censor it.
Speaker 1: Maybe we'll just skip it. We'll go straight to seventy.
Speaker 3: Yeah, seventy isn't new sixty nine.
Speaker 1: Nobody says that. Don't make that a thing.
Speaker 3: I don't care if other people say, oh I see,
Speaker 3: but yeah. We do like to answer questions here on
Speaker 3: the podcast that listeners said this, and so today we
Speaker 3: have three awesome questions. They are about galaxies colliding but
Speaker 3: extreme forces, and about the air we breathe. So let's
Speaker 3: jump right in. Our first question comes from Pedra from Boston.
Speaker 4: Hi, Daniel and jre I routinely hear not to worry
Speaker 4: about the impending collision between our galaxy and the Andromeda galaxy,
Speaker 4: since the space between the stars within each galaxy is
Speaker 4: so great there won't be any direct collisions. However, on
Speaker 4: some of the podcast episodes, it seems as though the
Speaker 4: orbital stability of the planets in our Solar system isn't
Speaker 4: all that great. For example, some planets may have traded places,
Speaker 4: while other planets could have been captured or ejected. So, really,
Speaker 4: which argument wins? Do I need to tell my descendants
Speaker 4: to start worrying about it in four point five billion years,
Speaker 4: I really want them to see the Sun become a
Speaker 4: red giant.
Speaker 1: Thanks for the great podcast.
Speaker 3: All right, interesting question. Basically, should we be worried four
Speaker 3: and a half billion years from now?
Speaker 1: Yeah, exactly if we're all alive, or should the zombies
Speaker 1: that have succeeded us, should they be worried about.
Speaker 3: What's going to happen? I think that's the best part
Speaker 3: of being a zombies is you don't have to worry
Speaker 3: about anything.
Speaker 1: As long as you've killed off all the people who
Speaker 1: might assign you homework problems, you're.
Speaker 3: Fine, man, I wou think the best part of being
Speaker 3: a zombies you can just turn your brain off.
Speaker 1: Don't you need to protect it from exploding? Right? Isn't
Speaker 1: that the kryptonite of zombies?
Speaker 3: Well, I think fire also kills zombies.
Speaker 1: Oh boy, wow, Yeah, I'm so glad you've been doing
Speaker 1: this research.
Speaker 3: I'm glad the people I'll be hanging out with know
Speaker 3: how to make a fire.
Speaker 1: But I think Petra's question is really touching on two
Speaker 1: things we hear about a lot in science. One that
Speaker 1: our galaxy is colliding with another galaxy and the other
Speaker 1: that our solar system is kind of fragile, that the
Speaker 1: orbits are not really that stable, and so he's worried
Speaker 1: that even if stars are pretty dilute in the galaxy,
Speaker 1: would our solar system get upset?
Speaker 3: Basically, what's going to happen when our galaxy collides with Andromeda?
Speaker 1: Like?
Speaker 3: Will be safe?
Speaker 4: Like?
Speaker 3: Is nothing going to happen to us? Or should we
Speaker 3: be concerned that maybe our plant might get disrupted and
Speaker 3: thrown out into space?
Speaker 1: Yeah, it's definitely a valid concern, and it touches on
Speaker 1: a lot of really interesting physics. And the first thing
Speaker 1: I want to talk about is why Andrama is going
Speaker 1: to collide with the Milky Way, because I get a
Speaker 1: lot of questions about exactly this. People hear us talking
Speaker 1: about how the universe is expanding and space is being
Speaker 1: created between galaxies, and then they hear us talking about
Speaker 1: how Andromeda is coming towards us and say, how does
Speaker 1: that make any sense? Why isn't space expanding between us
Speaker 1: and Andromeda and pushing it further and further away? And
Speaker 1: so first we should try to reconcile that apparent contradiction.
Speaker 4: Mm.
Speaker 3: Yeah, because we talked about like how because dark energy
Speaker 3: is expanding the universe, the galaxies out there getting further
Speaker 3: and further away from us, But we've also talked about
Speaker 3: how Drama is in a collision course with our galaxy.
Speaker 1: Yeah, And the answer comes down to distances, and dark
Speaker 1: energy is something that gets more powerful for distant objects.
Speaker 1: It's basically like a chunk of space grows a little bit,
Speaker 1: and so more chunks of space are growing more. So
Speaker 1: a little tiny chunk of space is hardly growing, but
Speaker 1: a vast distance between our galaxy cluster and a really
Speaker 1: distant other galaxy cluster that's kind of growing a lot.
Speaker 1: And gravity is the opposite. Gravity gets weaker with distance.
Speaker 1: As things get further apart, gravity fades away. So for
Speaker 1: stuff that's really close together, like the Earth and the Sun,
Speaker 1: or even our galaxy in the neighboring galaxy, gravity wins
Speaker 1: over dark energy. Things that are really really far apart,
Speaker 1: like clusters of galaxies, not individual galaxies. Dark energy is winning,
Speaker 1: And most of the universe is far apart from most
Speaker 1: of the universe, so mostly things are expanding away from
Speaker 1: each other, but in little neighborhoods like our cluster of galaxy,
Speaker 1: stuff is still getting pulled together by gravity. So gravity
Speaker 1: is the reason the Milky Way and Andromeda will collide
Speaker 1: in a few billion years.
Speaker 3: Is it gravity or is it just that we just
Speaker 3: happen to be in a course that intercepts the course
Speaker 3: of Andromeda, Like is Indrameda really being attracted to our galaxy?
Speaker 3: I mean, obviously it is, But is it really significant
Speaker 3: to call it the main reason we're going to collide
Speaker 3: with it?
Speaker 1: It definitely is. I mean, the Milky Way Andromeda are
Speaker 1: part of a cluster of galaxies, and that cluster exists
Speaker 1: because of gravity, so it's holding it together and the
Speaker 1: galaxies are sort of sloshing around. It's not guaranteed at
Speaker 1: any moment that they're going to hit each other, but
Speaker 1: it's gravity that holds them together, that's pulling them together.
Speaker 1: It's sort of like asking if a comet falls towards
Speaker 1: the Sun and it collides to the Sun, why is
Speaker 1: that Well, it's definitely because of the gravity. That doesn't
Speaker 1: mean that every comet does collide with the Sun. Gravity
Speaker 1: is not omnipotent. Sometimes comets go around the back of
Speaker 1: the Sun in the same way in the local cluster.
Speaker 1: Not every galaxy is gonna collide with every other galaxy
Speaker 1: as soon as possible. Sometimes they pass around each other.
Speaker 1: But it is gravity that's pulling these two together.
Speaker 3: Well, I guess what I mean is like if you
Speaker 3: have to asteroids, for example, in the Solar System, and
Speaker 3: they're gonna collide with each other. I mean, sure, they're
Speaker 3: in the Solar System together because of the gravity well
Speaker 3: of the Sun, but the fact that they're colliding with
Speaker 3: each other as opposed to not colliding, it's mostly just
Speaker 3: kind of look right, Yeah.
Speaker 1: It's gravity plus chance. It's possible a cluster where galaxies
Speaker 1: like ours and Andromeda don't collide until later on. Eventually
Speaker 1: everything is going to collide and it's all going to
Speaker 1: collapse into one supermassive black hole. So it's really just
Speaker 1: a waiting game.
Speaker 3: But the collision that's going to happen in four and
Speaker 3: a half billion years, that's basically luck. Right. It's not
Speaker 3: like it's inevitable. Like if our galaxy was moving a
Speaker 3: few degrees in another direction, or to the right or
Speaker 3: to the left, we wouldn't be colliding with Andromeda, would we.
Speaker 1: Yeah, that's right. If you change the initial conditions, that
Speaker 1: collision might happen later. It also might happen earlier, Right,
Speaker 1: it could be that we're lucky we got this far
Speaker 1: without colliding with Andromeda. So yeah, the whole system is
Speaker 1: very chaotic, but it is gravity. But gravity is really
Speaker 1: the only force at play here.
Speaker 3: And so the reason we're worried about Andromeda and not
Speaker 3: other galaxies is because the other galaxies are further away,
Speaker 3: and those are definitely moving away from us because of
Speaker 3: dark energy, or are some of them potentially getting closer
Speaker 3: to us.
Speaker 1: Everything in our galaxy cluster is gravitationally bound, which means
Speaker 1: it has enough gravity to hold itself together and resist
Speaker 1: the pull of dark energy, and galaxy clusters are like
Speaker 1: the biggest thing that have that property. Anything that's larger
Speaker 1: than that, what we call a supercluster, is probably too
Speaker 1: big and too spread out for gravity to hold itself together,
Speaker 1: and dark energy is going to win. So that's sort
Speaker 1: of the tipping point. So anything that's in our galaxy
Speaker 1: cluster is eventually going to collapse into one big, super
Speaker 1: massive black hole. And we're talking very very far in.
Speaker 3: The future unless dark energy changes, right, Yes, like if
Speaker 3: it accelerates, then it's going to get a little more crowded,
Speaker 3: but or if it like weekends, things might get a
Speaker 3: little room hear.
Speaker 1: Yeah, I think it's the opposite. If dark energy accelerates,
Speaker 1: then even our galaxy cluster is going to get torn
Speaker 1: apart because it becomes more powerful than gravity. We talked
Speaker 1: about that once on the podcast. There's even a theory
Speaker 1: of like phantom dark energy, where dark energy gets so
Speaker 1: powerful that it tears apart atoms and even protons. And
Speaker 1: if dark energy weakens, then gravity wins over larger distances
Speaker 1: and it might gather together even superclusters.
Speaker 3: Right, that's what I meant. I meant the opposite of what.
Speaker 1: I said, But you're definitely right, and the conceptual part,
Speaker 1: which is that we don't know what dark energy is
Speaker 1: or what it's going to do, and we can't really
Speaker 1: predict it. So this is assuming a naive extrapolation of
Speaker 1: dark energy, which is basically all we can do at
Speaker 1: this point.
Speaker 3: All Right, so we're in a collision course with Andromeda.
Speaker 3: What's going to happen when we collide?
Speaker 1: So when we collide with Andromeda, there's a bunch of
Speaker 1: different components of the galaxy, and you really need to
Speaker 1: think about each of them individually because they all have
Speaker 1: different behavior. So, for example, the gas and the dust
Speaker 1: that are in the two galaxies, those are going to
Speaker 1: collide and you're going to get all sorts of dramatic stuff.
Speaker 1: It's going to see the creation of lots of new stars,
Speaker 1: which would be really exciting. But the stars themselves are
Speaker 1: very different from the gas and the dust. Right the
Speaker 1: gas in the dust is very spread out, it's definitely
Speaker 1: going to smash into the other stuff. But stars are
Speaker 1: very different from gas and dust. They're not as spread out.
Speaker 1: They're tiny, and they're clumpy, and they're really really dilute.
Speaker 1: So when stars approach other stars, it's very hard for
Speaker 1: them to actually collide because space is really really big,
Speaker 1: and the stars are really really far apart.
Speaker 3: I guess how far apart are they? Like how far
Speaker 3: is there our year's neighbor?
Speaker 1: So our nearest neighbor is light years away, right, the
Speaker 1: closest star to us is almost four light years away,
Speaker 1: and the Sun is the tiny fraction of a light
Speaker 1: year wide. I mean, if you shrink, for example, the
Speaker 1: Sun down to the size of a tennis ball that
Speaker 1: you could hold in your hand, then the nearest neighbor
Speaker 1: star would be four or five thousand miles away.
Speaker 3: WHOA, that's like on the other side of the Atlantic kind.
Speaker 1: Of yeah, exactly. So imagine you're throwing a tennis ball
Speaker 1: and somebody on the other side of the ocean is
Speaker 1: throwing a tennis ball. What are the chances that they're
Speaker 1: going to hit each other over the ocean? Like basically zero?
Speaker 3: But I guess how wide is the sphere of influence
Speaker 3: of something like the sun? Like how close do you
Speaker 3: need to get to it before you feel it's gravity?
Speaker 1: Yeah? Exactly, good point, because we're not actually just interested
Speaker 1: in like a collision where like the two stars really
Speaker 1: touch each other and merge and become one. Stars can
Speaker 1: pull in each other if they're even near each other. Right,
Speaker 1: And that's really what Petro's quest is about, is how
Speaker 1: close does the star need to get to distort our
Speaker 1: star or distort the orbit of stuff around the star? Right?
Speaker 1: Because near misses can destabilize things, and we know that
Speaker 1: already in our galaxy, because other stars are moving relative
Speaker 1: to the Sun. Sometimes they come closer, sometimes they come
Speaker 1: further away, and that can distort the orbits of stuff
Speaker 1: in our Solar system. So it's not a clear, crisp answer.
Speaker 1: It's not like there's a certain distance within which something
Speaker 1: happens and out of which nothing happens. It's gradual, Right.
Speaker 1: The closer it comes, the greater the gravitational distortion.
Speaker 3: But I guess maybe it depends on how unstable our
Speaker 3: orbit is or how fragile our orbit is. Do you
Speaker 3: have a sense of how precarious are a path around
Speaker 3: the Sun is? Like if I bring in another Sun,
Speaker 3: I don't know, a few million miles away, is it
Speaker 3: going to affect us and kick us out of the
Speaker 3: Solar system or maybe cause us to fall into the Sun,
Speaker 3: or are we going to be Okay?
Speaker 1: Yeah, it's a good question. The Earth is pretty stable,
Speaker 1: like just the Earth in the Solar System is a
Speaker 1: pretty stable orbit. There's a lot of stuff going on
Speaker 1: that's going to influence the Earth's orbit that makes its
Speaker 1: orbit change. For example, like the Sun is losing mass,
Speaker 1: so it's gravity shrinks. The Sun is also pushing on
Speaker 1: the Earth, not just pulling on it with gravity, but
Speaker 1: its wind pushes on the Earth. There's effects of Jupiter,
Speaker 1: there's gravitational radiation. But you're right, the biggest wild card
Speaker 1: are like things from outside the Solar System. And this
Speaker 1: is something we've thought about, not just in the case
Speaker 1: of another galaxy, but again just stuff in our Solar system. So,
Speaker 1: for example, there is a star it's called Glease seven
Speaker 1: to ten that we've been tracking, and we predict that
Speaker 1: it's gonna come kind of close to our star. It's
Speaker 1: gonna come within one twenty fifth of the distance to
Speaker 1: Proxima Centauri. So Proximus Centauri is four light years away,
Speaker 1: and so this is gonna come like an eighth of
Speaker 1: a light year away from our star.
Speaker 3: Oh wait, wait, wait, so this is a star that's
Speaker 3: gonna come within one twenty fifth of the nearest star. Yeah,
Speaker 3: would it become the nearest star if it's coming close
Speaker 3: to us.
Speaker 1: Yeah, that's just for scale, our current nearest stars for
Speaker 1: light years away. This one's going to come within one
Speaker 1: twenty fifth of that distance again in the far far future.
Speaker 1: How far in the future, in about one and a
Speaker 1: half million years.
Speaker 3: Oh, that's pretty soon cosmically speaking.
Speaker 1: Yeah, it's a lot of generations to survive between now
Speaker 1: and then. But yeah, that's not far away, and it's
Speaker 1: definitely a lot sooner than when the Milky Way collides
Speaker 1: with Andromeda.
Speaker 3: And this is a star that's like traveling through space
Speaker 3: relative to us, or are we traveling close to it?
Speaker 3: You know what I mean? Like, is this an anomaly
Speaker 3: or in our quiet neighborhood or is it all part
Speaker 3: of the movement of the stars.
Speaker 1: It's part of all the movement of the stars around
Speaker 1: the center of the galaxy. You know, all the stars
Speaker 1: are orbiting the center and they orbit at different velocities. Also,
Speaker 1: the stars are moving up and down. They're sort of
Speaker 1: like wiggling through the plane of the galaxy. And so
Speaker 1: the stars that are in our immediate neighborhood change over
Speaker 1: millions of years as these stars sort of swim through
Speaker 1: the lazy river differently. So this is a totally normal
Speaker 1: thing to happen.
Speaker 3: And what does scientists predict this is going to happen
Speaker 3: when the start flies close to us? Is it gonna
Speaker 3: disrupt us? Or are we going to feel it?
Speaker 1: So we are probably not going to feel it directly,
Speaker 1: in the sense that it's not going to come close
Speaker 1: enough to perturb the Earth's orbit. So that's already kind
Speaker 1: of an answer, like you can come fairly close to
Speaker 1: the Solar System, you know, within an ace of a
Speaker 1: light year, and really have no effect on the Earth's
Speaker 1: orbit directly, but it could have serious impacts for life
Speaker 1: on Earth because it could impact stuff that's in the
Speaker 1: outer Solar System that could then rain down on the
Speaker 1: inner Solar System. The very far edges of the Solar System,
Speaker 1: past Pluto and all the dwarf planets is a theoretical
Speaker 1: cloud of trillions of icy objects called the Ort cloud.
Speaker 1: We think it's probably the source of long period comets.
Speaker 1: These things are really really far away compared to stuff
Speaker 1: in the inner Solar System or even to Pluto, and
Speaker 1: so a near passing star could disturb some of these.
Speaker 1: There's lots of them, and they take just like a
Speaker 1: little nudge to fall out of their orbit and come
Speaker 1: barreling into the inner Solar System, where they could become
Speaker 1: very high speed, very dangerous comets that could impact on
Speaker 1: the Earth.
Speaker 3: Whoa, but it maybe it might be get lucky not
Speaker 3: get hit by right, because even the space between us
Speaker 3: and the Sun is huge.
Speaker 1: Yeah, absolutely, we might get lucky and we could get
Speaker 1: protected by Jupiter.
Speaker 5: Right.
Speaker 1: Jupiter has a lot of gravity and it tends to
Speaker 1: shield the Inner Solar System by pulling these things towards it.
Speaker 1: Like when comet Shoemaker Levey came through the Solar System
Speaker 1: in the nineties, it impacted on Jupiter and that wasn't
Speaker 1: an accident. Not only is Jupiter just a much bigger target,
Speaker 1: but it has that gravity. But it's not a die
Speaker 1: you want to roll. It's sort of like playing cosmic
Speaker 1: Russian Roulette.
Speaker 5: You know.
Speaker 1: If a star comes by and dislodges a lot of
Speaker 1: art cloud objects tens millions even for example, then we're
Speaker 1: gonna have to get lucky a lot of times to
Speaker 1: avoid being hit. So that's the most likely scenario for
Speaker 1: Glease and also for the collision between Andromeda and the
Speaker 1: Milky Way, that our cloud gets perturbed.
Speaker 3: Well, well, but I guess what is the scenario that's
Speaker 3: going to happen when we collibe with Andromeda. Are we
Speaker 3: going to see a lot of these stars flying as
Speaker 3: close as Gleek or is it going to be worse
Speaker 3: because I imagine, you know, the nearest star to us
Speaker 3: is pretty far away, but you know, we're colliding with
Speaker 3: a cloud of one hundred billion stars. Maybe that increases
Speaker 3: the chances of something flying closer.
Speaker 1: Yeah. Actually, Andromeda is much bigger than the Milky Way.
Speaker 1: There's lots more stars in Andromeda than in the Milky Way.
Speaker 1: It's really a big, fat galaxy. I mean in a
Speaker 1: very positive way. And so there's no specific answers. There's
Speaker 1: just chances. Right. The chances of a direct collision are zero,
Speaker 1: the chances of a near miss are larger. The chances
Speaker 1: of stars flying sort of within a light year or
Speaker 1: so is reasonable. I haven't done the actual calculations, don't
Speaker 1: have numbers, but qualitatively it's extraordinarily unlikely for a direct
Speaker 1: star star collision. I think it's quite likely for a
Speaker 1: near miss like Glease seven to ten. But I think
Speaker 1: the most likely scenario is that no star comes really
Speaker 1: anywhere near us, though there are a lot of them.
Speaker 1: There are also very very spread out.
Speaker 3: No, should we just think your word for it, or
Speaker 3: should maybe one of you guys get on the computer
Speaker 3: and simulate this to figure it out.
Speaker 1: We've got four and a half billion years to figure
Speaker 1: it out, so yeah, that's enough computation time.
Speaker 3: I don't know. I like to plan ahead, as you know. No,
Speaker 3: you gotta get ready.
Speaker 1: The problem with these calculations is that the further in
Speaker 1: the future you have to extrapolate, the more uncertainty there is.
Speaker 1: Right Like, NASA can predict the path of these objects
Speaker 1: for one hundred years very precisely. You ask them to
Speaker 1: tell you where they're going to be in five billion years,
Speaker 1: they have no idea because small uncertainties add up over
Speaker 1: time to make those predictions essentially useless. So our understanding,
Speaker 1: for example, of the dark matter in the Milky Way
Speaker 1: will affect this and the dark matter and androma and the
Speaker 1: dark matter between us and them. So we could do
Speaker 1: a calculation and give you a number, but it's gonna
Speaker 1: be different next year, and it's gonna be different in
Speaker 1: a million years, it's gonna be different in a billion years.
Speaker 3: Well, I mean, you don't need to predict what's going
Speaker 3: to happen exactly, But could you maybe get us that
Speaker 3: this sense? Like if I take a cloud of stars
Speaker 3: like the Andromeda galaxy, and you take a cloud of
Speaker 3: stars like the Milky Way galaxy, and you smash them
Speaker 3: into each other at the speed are going, what are
Speaker 3: the chances or how likely or you know, how often
Speaker 3: would a star come near as enough to disrupt our orbit?
Speaker 1: That's totally possible, and probably somebody is working on that,
Speaker 1: but I haven't actually seen that number anywhere.
Speaker 3: All right, Well, then the answer for Petra is hopefully
Speaker 3: not nothing bad will happen. Daniel doesn't think.
Speaker 1: Don't worry too much about it, Petra. Zombies are much
Speaker 1: more likely.
Speaker 3: Yeah, don't collide with any zombies if you can't, especially
Speaker 3: when with teeth.
Speaker 1: But keep working on those intervals. That's going to save
Speaker 1: you in the end times.
Speaker 3: That's right. Bring your math book whenever you go out
Speaker 3: foraging for you know, particle colliders to start in your fire.
Speaker 1: Or do what my dad did. Become a blacksmith and
Speaker 1: make your own weapons.
Speaker 3: Oh yeah, that's a good suggestion. Or just go to
Speaker 3: Daniel's garage and you know, steal some of those swords.
Speaker 1: I wouldn't recommend that that's pretty well protected.
Speaker 3: By math. If you come within ten meters, you'll be
Speaker 3: faced with some physics questions, or you could just blast
Speaker 3: the podcast out in speakers. They'll keep everyone away. All right,
Speaker 3: let's get to our other questions here today, and we
Speaker 3: have some questions about extreme forces in the universe and
Speaker 3: about what kind of air are we all breathing? So
Speaker 3: we'll dig into those, but first let's take a quick break.
Speaker 4: Right.
Speaker 3: We're answering listener questions, and our second question comes from Derek,
Speaker 3: who comes from the planet Earth.
Speaker 1: I guess probably we hope, so, no, we hope not.
Speaker 3: Yeah, Hi Daniel and Jorge.
Speaker 5: So I have a question about extreme forces. Gravity is
Speaker 5: one of the weakest forces in nature, but it seems
Speaker 5: like there's no limit to how much gravity there can be,
Speaker 5: and once you have enough of it, an event horizon
Speaker 5: is formed and a black hole is made. Even then,
Speaker 5: more masks can be added and gravity will continue to increase.
Speaker 5: Can this be done with any of the other forces,
Speaker 5: Like can a magnetic field become so strong that it
Speaker 5: forms its own kind of event horizon? Or is there
Speaker 5: a limit that prevents the other forces from increasing infinitely?
Speaker 3: Thank you all, right, interesting question, I guess The question
Speaker 3: is how extreme can other forces get? Can you make
Speaker 3: like a magnetic black hole or a weak black hole?
Speaker 2: Yeah?
Speaker 1: Super fun question, really great to think about, and I
Speaker 1: love the sort of philosophy behind this question. Trying to
Speaker 1: make connections between forces and try to understand the differences
Speaker 1: between ideas. This is really how you make progress in physics.
Speaker 1: How you build a consistent model in your head, try
Speaker 1: to understand where that model doesn't work and where the
Speaker 1: bits don't fit together, and then try to understand how
Speaker 1: they can possi click together. So kudos to you, Derek
Speaker 1: for thinking about it this way and for asking this
Speaker 1: great question.
Speaker 3: All right, The question is Derek is wondering, like, we
Speaker 3: know that a black hole happens when you gravity gets
Speaker 3: so intense that it becomes basically a black hole with
Speaker 3: an event horizon. Can that sort of thing happen with
Speaker 3: the other forces in nature, like electromagnetism or the weak
Speaker 3: force or the strong force. Can you get a situation
Speaker 3: where the magnetic force is so strong it can maybe
Speaker 3: creates its own kind of event horizon.
Speaker 1: Yeah, so super fun question, and it's tempting to think
Speaker 1: that there is because Derek probably thinks about gravity as
Speaker 1: a force in the same way he thinks about magnetism
Speaker 1: as a force, and that it creates an acceleration on objects. Right,
Speaker 1: Two objects, as Newton described that have masks will pull
Speaker 1: on each other the same way two objects with electric charge,
Speaker 1: the electric force will pull on them or push on them,
Speaker 1: and the strong force pulls and pushes on things that
Speaker 1: have color charge. And so it's tempting to think about that,
Speaker 1: and it's very intuitive, but remember that gravity is not
Speaker 1: actually a force. It's our understanding of gravity today is
Speaker 1: that it represents the curvature of space time itself, and
Speaker 1: in many ways that's equivalent. Like most of the time,
Speaker 1: you can think about the curvature of space time and
Speaker 1: from that you can get exactly the same behavior that
Speaker 1: Newton would have predicted, but it's also crucially different in
Speaker 1: many respects. There's lots of things that the curvature of
Speaker 1: space time can do that the simple force of gravity
Speaker 1: cannot do. And form an event horizon is one of
Speaker 1: those things. So Einstein's reconception of gravity as a curvature
Speaker 1: of space time describes all of Newton's physics, but also
Speaker 1: more than that, it doesn't just reformulate gravity. As another
Speaker 1: way to think about it, it adds new capacity to gravity,
Speaker 1: new things that it can do. And so the force
Speaker 1: description of gravity cannot create an event horizon, but the
Speaker 1: curvature description of gravity can create event horizons. And so
Speaker 1: the other forces which can't be described in terms of
Speaker 1: curvature can't create event horizons. That's not something a force
Speaker 1: can do. Only spacetime curvature can do that.
Speaker 3: Well, I guess I might ask, are you sure about that?
Speaker 3: Couldn't you define the event horizon as the point at
Speaker 3: which the force of gravity is so strong that nothing
Speaker 3: can escape it.
Speaker 1: I'm definitely not sure about that, because we don't understand
Speaker 1: gravity right. Gravity is really weird. Einstein's theory is beautiful,
Speaker 1: but we also know that it's flawed. We don't understand
Speaker 1: how singularities could form. We don't understand why gravity seems
Speaker 1: to not be quantum mechanical, or if it is when
Speaker 1: you zoom in enough, for example. So everything we say
Speaker 1: here today assumes that GR is correct, but we know
Speaker 1: that GR is not correct ultimately, and so there's lots
Speaker 1: of things to be learned, and in the far future
Speaker 1: this could all be totally wrong. So yeah, absolutely not,
Speaker 1: But you're right. First, we should define what we mean
Speaker 1: by an event horizon, right, And the reason a black
Speaker 1: hole can exist, the reason we have event horizons, the
Speaker 1: reason that curvature can do this and the forces cannot,
Speaker 1: is that curvature does something to space. It changes the
Speaker 1: shape of space, like the relationship between points. So you
Speaker 1: can think about it as like a region from which
Speaker 1: even a photon cannot escape, right, And that again is
Speaker 1: something gravity can do. But you can't do that with
Speaker 1: magnetism or electric force or the strong force.
Speaker 3: Well, I guess what I mean is, like, you know,
Speaker 3: for example, you might say that the Earth has an
Speaker 3: event horizon, right, Like there's a point and a velocity
Speaker 3: at which you can escape to Earth, and there's a
Speaker 3: point at which you cannot escape Earth. Right, So maybe
Speaker 3: you might be able to call that the event horizon
Speaker 3: of the Earth gravity black holes event horizon. It's just that.
Speaker 3: But taking to the extreme where you're talking about not
Speaker 3: even light being able to escape, I wonder if you
Speaker 3: can do that the same with a magnetic field or
Speaker 3: electromagnetic force, Like is there a point at which not
Speaker 3: even like a super fast moving charged particle will escape
Speaker 3: the attractive force that something has electromagnetically.
Speaker 1: I mean, you can definitely form bound states, right, Like
Speaker 1: the Moon is bound to the Earth gravitation, but it
Speaker 1: can still escape, right, Or photons from the Moon can
Speaker 1: definitely escape the gravitational system. And that's not just like
Speaker 1: a difference in degree, it's a difference in kind. Right.
Speaker 1: The inside of an event horizon really is cut off
Speaker 1: from the rest of the universe. Nothing that happens there
Speaker 1: can influence anything that happens outside the universe, whereas things
Speaker 1: that happen on Earth can always influence things far away.
Speaker 1: It just takes some time. So it's a question of
Speaker 1: like causality, like are these things linked or not? Can
Speaker 1: one area of space affect another? You can definitely attract
Speaker 1: things together, and they can even be stuck together, and
Speaker 1: they can be stable, and they can even last for
Speaker 1: millions or billions of years or configurations, Like the proton
Speaker 1: might last forever, but you know, the quarks inside the
Speaker 1: proton could still potentially escape you give them enough energy.
Speaker 1: It's a bound stay. That's not the same thing as
Speaker 1: an event horizon.
Speaker 3: But could you say that, like a charge ball of
Speaker 3: electricity has an escape velocity to it and a point
Speaker 3: at which no charge particle can escape it.
Speaker 1: A charge ball, for example, definitely has an escape velocity,
Speaker 1: like there's a minimum energy you would need to escape
Speaker 1: the potential well created by that ball, and things below
Speaker 1: that energy are bound to it, but there is still
Speaker 1: always an escape velocity. And that's why photons are a
Speaker 1: useful way to think about event horizons, because there's no
Speaker 1: force that can bound a photon. Like photons always move
Speaker 1: at the speed of light locally, and there's no force
Speaker 1: that can prevent them from doing that. But changing the
Speaker 1: direction of space, right, changing the configuration of space the
Speaker 1: way gravity does, that can trap a photon because it
Speaker 1: can change space from flat to curve. You can make
Speaker 1: the photon move in a circle forever, which is sort
Speaker 1: of amazing. And so that's why gravity can do this,
Speaker 1: which no other force can do.
Speaker 3: But I guess light is an electrically neutral right, Yeah,
Speaker 3: So I wonder if you can envision, like, is there
Speaker 3: a ball of charge that can be so intense that
Speaker 3: not even a core going at the speed of light
Speaker 3: can escape it? Do you maybe call that the event
Speaker 3: horizon of an electromagnetic force.
Speaker 1: So you take a ball of charge has a very
Speaker 1: strong electric force, right, and now imagine some electron near it,
Speaker 1: and you're wondering, like, is it possible to have that
Speaker 1: ball be so electrically charged that even an electron moving
Speaker 1: at the speed of light couldn't escape it. Yeah, yeah,
Speaker 1: it's a great question. The problem is that electrons can't
Speaker 1: move at the speed of light because they have mass.
Speaker 3: Right, Well, of course I know this, but like, if
Speaker 3: it was moving at the speed of light, is there
Speaker 3: a point we're closing on nin point nine nine nine percent? Yeah,
Speaker 3: the speed of light. Is there an event horizon for
Speaker 3: that ball of positive charge?
Speaker 1: Right? And I bring up the velocity not just to
Speaker 1: be like actually, but because velocity is the wrong way
Speaker 1: to think about it, because for a massive object, energy
Speaker 1: is the right way to think about it. As you say,
Speaker 1: it can't get to the speed of light. You can
Speaker 1: get arbitrarily close, but there's no limit to the amount
Speaker 1: of energy that an electron can have, and so you
Speaker 1: can just keep putting energy into that electron and eventually
Speaker 1: it will escape that ball of charge. So no, there's
Speaker 1: no way you can trap an electron forever. You can't
Speaker 1: create an event horizon using electric charge. You could always
Speaker 1: just give that electron more energy and it would escape
Speaker 1: your ball of charge no matter how big it is.
Speaker 3: All right, So then the answer for Derek is no,
Speaker 3: you can't make an electromagnetic black hole.
Speaker 1: Yeah, and I think there's another wrinkle there, which is
Speaker 1: something you brought up, which is photons are neutral electromagnetically, right,
Speaker 1: And I think that's really cool. I'm kind of weird
Speaker 1: that photons, even though they carry electromagnetic information, they don't
Speaker 1: feel the force themselves. And that's something true about all
Speaker 1: of the forces, electromagnetism, the weak force, a strong force,
Speaker 1: there are always some particles that are neutral to it, right, So,
Speaker 1: like the strong force can create really really strong bound states,
Speaker 1: but then neutrinos ignore it, right, they would just fly
Speaker 1: right through it. So in that sense, an event horizon
Speaker 1: for like electromagnetism wouldn't really be an event horizon even
Speaker 1: if you could make one, because some particles ignore it.
Speaker 1: The amazing, awesome thing about gravity is that nothing can
Speaker 1: ignore it. Gravity is just linked to energy. So anything
Speaker 1: that has energy, which is basically anything in the way
Speaker 1: we conceive of it, is affected by gravity. It's inescapable.
Speaker 3: Oh all right, hmm I'm still wondering, like, could you
Speaker 3: make that calculation? Like, what did you take an electron,
Speaker 3: give it the speed of light? Could you use that
Speaker 3: to compute a positive ball of charge strong enough for
Speaker 3: which that's the escape velocity.
Speaker 1: Well, if you have an electron and you effectively give
Speaker 1: it velocity the speed of light, you're giving it infinite energy.
Speaker 1: And of course that's impossible. But what that means is
Speaker 1: that there is no ball of charge that's powerful enough
Speaker 1: to bound it because there's infinite energy, so has more
Speaker 1: energy than any energy level in that bound state unless
Speaker 1: you make that ball infinite. Right, So now it's like
Speaker 1: infinity versus infinity.
Speaker 3: Well, I guess what I mean is like, when you
Speaker 3: compute the escape velocity of something escaping Earth, you're not
Speaker 3: actually using the relativistic equations, right, You're just kind of
Speaker 3: using more basic math. You're ignoring relativist effects.
Speaker 1: Right, Yeah, the simplest calculations ignore relativistic effects. But I
Speaker 1: don't think relativistic effects are really relevant for the Earth.
Speaker 3: Right, But so let's say I do that for an electron,
Speaker 3: give it the speed of light. Could I compute an
Speaker 3: event horizon, even though maybe it's not realistic, but it
Speaker 3: is there. One.
Speaker 1: So you're saying, if I ignore the fact that electrons
Speaker 1: can't go the speed of light and I ignore relativity,
Speaker 1: can we make an event horizon for an electron.
Speaker 3: Yeah, just like when we compute the escape velocity of
Speaker 3: a satellite or a spacecraft, we sort of ignore that too.
Speaker 1: You can definitely calculate and escape velocity right or effectively
Speaker 1: an energy beyond which the electron is free and below
Speaker 1: which the electron is bound. So you can definitely calculate that.
Speaker 1: You can ignore relativity, you can include relativity or whatever.
Speaker 1: But in order to trap that electron forever so that
Speaker 1: there's no chance that ever leaves, then you essentially need
Speaker 1: an infinitely powerful electric force. You need an infinite amount
Speaker 1: of charge to trap an electron that could effectively have
Speaker 1: infinite energy.
Speaker 3: So would that mean that my electric black hole is
Speaker 3: infinitely big or infinitely small?
Speaker 1: It would be infinitely charged.
Speaker 3: Oh does it have to be in constily charged or
Speaker 3: could it just be a charge but infinitely dense.
Speaker 1: You might imagine bringing the electron like really really close
Speaker 1: to that charge so that the electric force gets really powerful,
Speaker 1: because the electric force also gets powerful as things get
Speaker 1: really close together. But again, these are quantum objects. There's
Speaker 1: always like a minimum effective radius. It's not really an orbit,
Speaker 1: but this is like a mean distance from the center
Speaker 1: for the ground state, and so that effectively limits how
Speaker 1: powerful these things can get. Like there's a reason the
Speaker 1: hydrogen atom has a ground state and the electron is
Speaker 1: not closer to it. It can't settle any closer, and
Speaker 1: that effectively bounds like how strong the force can get.
Speaker 3: Oh Man, So you're seeing quantum mechanics ruins all the time.
Speaker 1: Like usual, But you also have another question about like
Speaker 1: why can't we describe the other forces in terms of curvature?
Speaker 1: And there are people working on that, people wondering like, well,
Speaker 1: what if electromagnetism actually is curvature but not in our
Speaker 1: three D space? What if it's curvature in like additional
Speaker 1: spatial dimensions. And nobody's really made that theory work, but
Speaker 1: it's really fun to think about how electromagnetism might be
Speaker 1: like curvature in other ways that we can't see it yet.
Speaker 1: And even in that theory, you might be able to
Speaker 1: describe electromagnetism as curvature, and you might wonder like can
Speaker 1: I make event horizons in those other dimensions, but then
Speaker 1: you wouldn't be making event horizons in our three D space,
Speaker 1: which I think is really what the question was.
Speaker 3: So then it would be sort of like a black hole.
Speaker 3: But the inn other dimensions.
Speaker 1: It's pretty hard to think about, but it would be
Speaker 1: curvature in other dimensions, and you might have event horizons
Speaker 1: in those dimensions, but not in our dimensions, So pretty
Speaker 1: wonky stuff.
Speaker 3: There'd be holes in our black hole, is basically.
Speaker 1: What you're saying.
Speaker 3: Yeah, exactly, all right, Well that's an interesting answer for Derek.
Speaker 3: Now let's get to our last question of today, and
Speaker 3: it's about the air we breathe and where does part
Speaker 3: of it come from? So let's dig into that question,
Speaker 3: but first let's take a quick break. We're answering listener
Speaker 3: questions here today and our last question comes from Steve
Speaker 3: paren from Quebec.
Speaker 2: Hi, Daniel and Jorge, this is Steve Pargan from Quebec, Canada.
Speaker 2: My question is where is all the nitrogen in our
Speaker 2: atmosphere coming from? And what role does it play? Amazing podcast, guys,
Speaker 2: I love it, Thank you.
Speaker 3: All right, A pretty straightforward question here, Where does all
Speaker 3: the nitrogen in our atmosphere come from and what role
Speaker 3: does it play?
Speaker 1: Yeah, nitrogen is a big deal on Earth. Like, most
Speaker 1: of the atmosphere is nitrogen. You take a deep breath,
Speaker 1: you think yourself as a gulping oxygen, but it's mostly
Speaker 1: nitrogen that you're breathing in, which is kind of weird.
Speaker 3: Well, what do you mean mostly? What are the percentages?
Speaker 1: It's almost eighty percent of the air is nitrogen.
Speaker 3: Eighty percent by like a volume mass or adams.
Speaker 1: It's seventy eight percent by mass.
Speaker 3: And how much of it is oxygen? So it's like
Speaker 3: most of the air is nitrogen.
Speaker 1: It's seventy eight percent by quantity.
Speaker 3: You mean by volume or what do you mean by
Speaker 3: quantity like number of atoms?
Speaker 1: Yeah, like number of molecules. Actually, if you count it up,
Speaker 1: if you take like a cubic meter of air and
Speaker 1: you count all the molecules in it, seventy eight percent
Speaker 1: of those are nitrogen and twenty one percent of those
Speaker 1: are oxygen.
Speaker 3: Oh, no, hydrogen.
Speaker 1: There's almost no hydrogen in the atmosphere because it's very volatile.
Speaker 1: Any hydrogen will react with the oxygen and make water.
Speaker 3: So where did all this nigrogen come from?
Speaker 1: Yeah, it's a really fun question. It goes back to
Speaker 1: the whole origin of like why we have an atmosphere
Speaker 1: in the first place, because it's kind of weird. You
Speaker 1: know that we have enough gravity to like hold this
Speaker 1: little super thin envelope of gas around the planet. And
Speaker 1: if you think about how the planet came to be,
Speaker 1: it's not clear, like why we have an atmosphere that
Speaker 1: survived the formation of the Solar System, because as things
Speaker 1: were condensing very early in the Solar System, it was
Speaker 1: a very volatile place. Like first of all, we're in
Speaker 1: the Inner Solar System, which means we're pretty close to
Speaker 1: the Sun, and so most of the hydrogen in the
Speaker 1: Inner Solar System was gobbled up by the Sun. Like
Speaker 1: the Sun has huge gravity. The reason that Earth was
Speaker 1: formed is because it's not hydrogen. It's because it's rocky,
Speaker 1: had like enough gravity to form its own little gravitational
Speaker 1: well and cluster stuff together before it all got gobbled
Speaker 1: up by the Sun. But that tends to gather together
Speaker 1: heavy things like rocks and metal, right, chunks of iron
Speaker 1: floating in space, not clouds of gas, most of which
Speaker 1: fell into the Sun. Some of it did form with
Speaker 1: the Earth. But then when the Sun started fusing, it
Speaker 1: created all this intense radiation and blasted away our atmosphere.
Speaker 1: So we might have had like a very thin hydrogen
Speaker 1: atmosphere to begin with, but then most of that got
Speaker 1: lost due to the solar radiation and then also collisions
Speaker 1: by heavy stuff, like the formation of the Moon was
Speaker 1: due to this collision with a protoplanet and that probably
Speaker 1: destroyed all the atmosphere we had initially.
Speaker 3: But I guess a deeper question is where it did
Speaker 3: all come from originally, Like it just got form inside
Speaker 3: the Sun like all the other heavy elements in previous
Speaker 3: iterations of the Sun or supernova or what.
Speaker 1: All the nitrogen and everything in our Solar system that
Speaker 1: isn't hydrogen was not made by our star, right, All
Speaker 1: that was made by previous stars. So like the deeper
Speaker 1: history is that we have mostly hydrogen formed in very
Speaker 1: very early universe, tiny tiny trace amounts of helium, and
Speaker 1: then you have to wait for stars to be born
Speaker 1: hundreds of millions of years later to turn that hydrogen
Speaker 1: into heavier stuff. And so that nitrogen that you're breathing
Speaker 1: right now was made at the heart of stars previous
Speaker 1: generations which burned created that nitrogen inside them and then
Speaker 1: blew up and spread those heavier elements, including nitrogen and
Speaker 1: iron and copper and on carbon and all that good
Speaker 1: stuff throughout the galaxy, and then that re coalesced into
Speaker 1: our solar system. So all the nitrogen and the iron
Speaker 1: and all that stuff in our bodies and in the
Speaker 1: air and in the Earth was made by a different
Speaker 1: star that no longer exists.
Speaker 3: And it was made at the core of that previous star,
Speaker 3: or when it exploded.
Speaker 1: The stuff that's iron or lighter was made to the
Speaker 1: core of that stars made by fusion, because when you
Speaker 1: fuse two lighter elements together, you release energy. But that's
Speaker 1: only true up to making iron beyond iron, When you
Speaker 1: fuse stuff together, it costs energy. So if a star
Speaker 1: starts to do that, it begins to dim and like
Speaker 1: steals away the energy. And stars need that energy to
Speaker 1: survive because they're fighting against gravity. Gravity is trying to
Speaker 1: compress them down into a black hole. And the only
Speaker 1: reason the star survives for millions or billions of years
Speaker 1: is that radiation pressure outwards that's created by the energy
Speaker 1: released by fusion. If that goes away, then the star
Speaker 1: starts to collapse, and so stars can't make a lot
Speaker 1: of the heavier elements above iron. For that, you need
Speaker 1: either the death of the star, the supernova which has
Speaker 1: super dense conditions capable of creating those heavier elements, or
Speaker 1: things later on like collisions of neutron stars to create
Speaker 1: the heaviest elements. But nitrogen is made in the heart
Speaker 1: of those stars during normal fusion.
Speaker 3: So we're basically breathing dead stars. Every time you take a.
Speaker 1: Breath, it's a gift from those stars.
Speaker 3: You're basically breathing zombie star.
Speaker 1: Yes, exactly, zombie star brains. Take a deep breath.
Speaker 3: Yeah, h smells delicious, smells like brains. So the previous
Speaker 3: star made the It was floating around just like all
Speaker 3: the hydrogen and carbon and dust and rocks that was
Speaker 3: made by previous stars when our Sun started burning. And
Speaker 3: then how did it end up on Earth or is
Speaker 3: it spread out all around the Solar System?
Speaker 1: It's all over the Solar System. Nitrogen is everywhere, It's
Speaker 1: not just on Earth. And the nitrogen in our atmosphere
Speaker 1: ended up on Earth in an interesting way. Number One,
Speaker 1: it came from the bombardment of the Earth by like
Speaker 1: comets and asteroids that had like frozen nitrogen in them,
Speaker 1: and so we think, like a lot of the water
Speaker 1: on Earth may have come from comets, the same thing
Speaker 1: is true of nitrogen. The early Earth was blasted clean. Essentially,
Speaker 1: it was just a bare rock because of the solar radiation.
Speaker 1: But then it got a second atmosphere due to collisions
Speaker 1: and also because of nitrogen and other gases trapped inside
Speaker 1: the Earth which escaped out due to like volcanoes. You know,
Speaker 1: you have a lot of these gases in the early Earth,
Speaker 1: and as the Earth is settling, the heavy stuff goes
Speaker 1: down to the core and the lighter stuff rises in
Speaker 1: the mantle, and then some of that escapes through cracks
Speaker 1: in the Earth. So volcanoes and the bombardment of asteroids
Speaker 1: created our second atmosphere, which was mostly nitrogen and carbon dioxide.
Speaker 1: So that's where the nitrogen comes.
Speaker 3: From, and then eventually we got oxygen. But I guess
Speaker 3: the second part of these question is what a role
Speaker 3: does nitrogen play? Like do our bodies need a nitrogen
Speaker 3: or do we just ignore it?
Speaker 1: Mostly? Yeah, it's definitely not inert. Nitrogen plays a really
Speaker 1: important role in the life cycle here on Earth, Like
Speaker 1: plants need nitrogen. It's a crucial part of a lot
Speaker 1: of the you know acids, and so in order for
Speaker 1: plants to grow, you need nitrogen in the soil, a
Speaker 1: big component of like fertilizer that people are constantly putting
Speaker 1: onto their plants, farmers and pour huge amounts of it.
Speaker 1: The reason you put manure on fields is that it
Speaker 1: has nitrogen in it and other stuff. So plants need
Speaker 1: this nitrogen in order to grow. And there are these
Speaker 1: bacteria that will breathe the nitrogen from the atmosphere and
Speaker 1: then basically make it available for the plants. So there's
Speaker 1: a whole complicated nitrogen cycle that involves like these nitrogen
Speaker 1: fixing bacteria and then plants using it to grow, and
Speaker 1: animals eating it and then pooping it back out into
Speaker 1: the ground. And it's a very complex cycle, but it's
Speaker 1: definitely not inert It's a huge part of life on
Speaker 1: Earth right right.
Speaker 3: And I just want to take a quick moment here
Speaker 3: to note that you were the first one to bring
Speaker 3: up poop in this episode, not me.
Speaker 1: Is that something you keep track of who says poop first?
Speaker 3: I'm just saying sometimes they get you know, accused of.
Speaker 1: Cultural language is down. Yeah, Well you know that's the
Speaker 1: conversation we have at my house all the time because
Speaker 1: my wife works on the gut microbiome, like literally, what's
Speaker 1: happening inside your guts? And so the kids are always
Speaker 1: timing like how long till mom brings up poop at
Speaker 1: the dinner table? Oh boy? And it's never very long.
Speaker 3: May should you just call it nigrogen instead of poop
Speaker 3: nigrogen rich content. They'll spare your appetites.
Speaker 1: We're just fertilizing the conversation.
Speaker 3: Yeah, you just want to make it more fregrant. But
Speaker 3: I guess why is nigrogen important and biological processes? Is
Speaker 3: it something There's something special about that molecule, you know,
Speaker 3: because carbon has some special things about it that make
Speaker 3: it kind of crucial to life. Is nudigen similar?
Speaker 1: Well, I think you're getting pretty deep into the chemistry here.
Speaker 1: You know, the amino acids are the basic building blocks
Speaker 1: of life, and having different kinds of atoms there, it
Speaker 1: gives you different options, different things you can build. But yeah,
Speaker 1: dot dot dot chemistry. I guess.
Speaker 3: To be a Wikipedia later.
Speaker 1: I mean, nitigen is already at the edge of my
Speaker 1: ability to think about things. There's so many protons there,
Speaker 1: it's crazy and then you have it connected.
Speaker 3: With another your brain would explode.
Speaker 1: Yeah, exactly, too many integrals from me.
Speaker 3: For as a physicist zombie. You just have to throw
Speaker 3: some chemistry questions at them, absolutely, and then their brains
Speaker 3: will explode.
Speaker 1: Yes, chemistry is our kryptonite for sure. And they don't
Speaker 1: even have to be that hard, just like my high
Speaker 1: schoolers ap chemistry questions. Whoa headache? Time?
Speaker 2: Right?
Speaker 4: Right?
Speaker 3: Hey Daniel, what's up? Regardless number big Welcome to Jorge
Speaker 3: explains the universe. All right, Well that's the answer for Steve,
Speaker 3: which is that the nigogen we're all breathing, eighty percent
Speaker 3: of the air we're breathing, came from a debt previous
Speaker 3: star in our solar system. Then it got formed with
Speaker 3: the rest of the Earth and the rocks and the
Speaker 3: other elements, and that's how we're breathing it today, that's right,
Speaker 3: possibly from comments, possibly from the earth burping.
Speaker 1: Yeah, exactly. And there's been some people doing really interesting
Speaker 1: studies to try to understand exactly where this nitrogen came from,
Speaker 1: because not all nitrogen is the same. Some of them
Speaker 1: have different isotope ratios, and you can tell like, was
Speaker 1: it formed in the Outer Solar System or the Inner
Speaker 1: Solar System, the molecules, not the pure nitrogen which was
Speaker 1: made in the stars. And so there are these studies
Speaker 1: that tell us that some of the nitrogen on Earth
Speaker 1: came from the Inner Solar System and some definitely came
Speaker 1: from the Outer Solar System. So it's a similar question
Speaker 1: to like where did our water come from?
Speaker 3: All right, well, three awesome questions here today. Thanks to
Speaker 3: all of our listeners who sent in their questions.
Speaker 1: And thanks to everybody who asks questions. Please don't be shy.
Speaker 1: Write to us two questions at Daniel and Jorge dot com.
Speaker 1: You'll definitely hear back from us.
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