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Speaker 4: When you pull up to game night, Ay, all new Camri,
Speaker 4: but it's actually Bingo.
Speaker 1: Night Minigolf anyone, It's a Camri five, the all new
Speaker 1: all hybrid Camri Toyota. Let's go places. Hey, Orge, are
Speaker 1: you preparing your kids for when the end times come?
Speaker 5: Oh?
Speaker 6: You mean when bananas go extinct? Or do you mean
Speaker 6: 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 6: I feel like I've been preparing my whole life. If
Speaker 6: there's a post apocalyptic movie out there, I.
Speaker 1: Probably see it. Well, then I hope you're teaching your
Speaker 1: kids some useful skills, you know, blacksmithing, martial arts, cartooning.
Speaker 6: Oh yeah, cartooning for sure, that's going to come in handy.
Speaker 6: 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 6: 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.
Speaker 6: Or are you going to be like, you know, freezing
Speaker 6: out there, and you're going to be like, oh no, no, sorry,
Speaker 6: the fire is just not fundamental enough for me.
Speaker 1: I think I would be hiding in my cave eating
Speaker 1: the last of the world world's chocolate reserves.
Speaker 6: Would that be a useful skill? You could be it
Speaker 6: the world's only chocolate tear. Hopefully the zombies like chocolate.
Speaker 1: Dark chocolate is the world's final currency.
Speaker 6: I am Jorge make carctoonist and the author of Oliver's
Speaker 6: 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 6: You're like, how can I make my time here on
Speaker 6: 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 6: I see, but you could have picked something positively useful,
Speaker 6: 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 6: He became a blacksmith. Wow, was he forging like swords
Speaker 6: or internal combustion engines in your garage?
Speaker 1: Or what swords? Spears? All kinds of stuff?
Speaker 6: Yes, he's like, I want to eat more weapons.
Speaker 1: I wish I were joking more and.
Speaker 6: More direct, but anyways, Welcome to our podcast, Daniel and
Speaker 6: 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 tiny little basic bits, that somehow they're danced together
Speaker 1: can explain everything that we experience in the universe. We
Speaker 1: can somehow find fundamental laws, and then we can also
Speaker 1: make sense of it all.
Speaker 6: That's right. We try to hone our knowledge of signs
Speaker 6: here and try to prepare you for the end times
Speaker 6: when we'll all be looking up at the stars wondering
Speaker 6: how do we all get here and how do we
Speaker 6: avoid those 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 6: Yeah, I'm sure having physics knowledge will be helpful only
Speaker 6: in the apocalypse, right, you can, I guess, try to
Speaker 6: build 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 6: Oh, that could be another way to defeat them. You know,
Speaker 6: you give them physics problems that are so tricky that
Speaker 6: their brains explode, and that everyone knows that's how you
Speaker 6: kill zombies.
Speaker 1: Wow, Yes, exactly too many into girls.
Speaker 6: Coculus.
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 6: Wasn't he really into currencies too.
Speaker 1: Mm hmmm, yeah, exactly.
Speaker 6: At some point became like a coin master or something.
Speaker 1: He was definitely a weird dude.
Speaker 6: Yes, by word, do you mean a genius who basically
Speaker 6: 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 6: Oh well, I'm sure a lot of people will be
Speaker 6: relieved to learn it's useful for something after all that
Speaker 6: work in high school.
Speaker 1: Yeah, they can integrate it into their lives.
Speaker 6: Oh boy, that was very ridico. But anyways, we do
Speaker 6: like to think about the universe and we try to
Speaker 6: explain it here on the podcast, and sometimes that involves
Speaker 6: 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
Speaker 1: podcast or something you heard about on gas another podcast,
Speaker 1: please write to me to questions at Danielanjorge dot com.
Speaker 1: We'll clear it up for you.
Speaker 6: Yeah, because it's part of human nature to be asking questions,
Speaker 6: and it's totally fun to ask questions as well, and
Speaker 6: so here in the podcast we sometimes like to answer
Speaker 6: questions that listeners send us, and so to be on
Speaker 6: the podcast, we'll be tackling listener questions number sixty six.
Speaker 1: You have a sixty six related snide.
Speaker 6: Comment warning, Daniel. If we keep going, we're gonna hit
Speaker 6: listener questions six sixty six.
Speaker 1: Oh, I thought you were going to warn you about
Speaker 1: listener question sixty nine, where we turned everything upside down.
Speaker 6: I have warned you repeatedly about that milestone, and you
Speaker 6: don't seem very concerned.
Speaker 1: I'm mindlessly barreling towards it.
Speaker 6: We'll 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 6: Yeah, seventy isn't sixty nine.
Speaker 1: Nobody says that. Don't make that a thing.
Speaker 6: I don't care if other people say, oh, I see,
Speaker 6: but yeah. We do like to answer questions here on
Speaker 6: the podcast that listeners said this, and so today we
Speaker 6: have three awesome questions. They are about galaxies colliding but
Speaker 6: extreme forces, and about the air we breathe. So let's
Speaker 6: jump right in. Our first question comes from Pedra, who
Speaker 6: hails from Boston.
Speaker 1: Hi, Daniel, and Jor.
Speaker 7: I'm routinely here not to worry about the impending collision
Speaker 7: between our galaxy and the Andromeda galaxy, since the space
Speaker 7: between the stars within each galaxy is so great there
Speaker 7: won't be any direct collisions. However, on some of the
Speaker 7: podcast episodes, it seems as though the orbital stability of
Speaker 7: the planets in our solar system isn't all that great?
Speaker 7: For example, some planets may have traded places, while other
Speaker 7: planets could have been captured or ejected. So really, which
Speaker 7: argument wins? Do I need to tell my descendants to
Speaker 7: start worrying about it? In four point five billion years,
Speaker 7: I really want them to see the Sun become a
Speaker 7: red giant. Thanks for the great podcast.
Speaker 6: All right, interesting question. Basically, should we be worried four
Speaker 6: 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 6: What's going to happen? I think that's the best part
Speaker 6: of being a zombies. You don't have to worry 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 6: Fine, man. I think the best part of being a
Speaker 6: zombie is you can just turn your brain off.
Speaker 1: Don't you need to protect it from exploding?
Speaker 5: Right?
Speaker 1: Isn't that the kryptonite of zombies?
Speaker 6: 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 6: I'm glad the people I'll be hanging out with know
Speaker 6: 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 6: Basically, what's going to happen when our galaxy collides with Andromeda?
Speaker 4: Like?
Speaker 6: Be safe? Like, is nothing going to happen to us?
Speaker 6: Or should we be concerned that maybe our plant might
Speaker 6: get disrupted and 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 first thing I
Speaker 1: want to talk about is why Andrama is going to
Speaker 1: collide with the Milky Way, because I get a lot
Speaker 1: of questions about exactly this. People hear us talking about
Speaker 1: how the universe is expanding and space is being created
Speaker 1: between galaxies, and then they hear us talking about how
Speaker 1: Andromeda is coming towards us and say, how does that
Speaker 1: make any sense? Why isn't space expanding between us and
Speaker 1: Andromeda and pushing it further and further away. And so
Speaker 1: first we should try to reconcile that apparent contradiction.
Speaker 6: Mm. Yeah, because we talked about like, how because dark
Speaker 6: energy is expanding the universe, the galaxies out there getting
Speaker 6: further and further away from us. But we've also talked
Speaker 6: about 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 6: Is it gravity? Or is it just that we just
Speaker 6: happen to be in a course that intercepts the course
Speaker 6: of Andromeda, Like, is Indrameda really being attracted to our galaxy?
Speaker 6: I mean, obviously it is, but is it really significant
Speaker 6: to call it the main reason it's we're going to
Speaker 6: collide 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 exhibits
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 6: Well, I guess what I mean is like if you
Speaker 6: have to asteroids, for example, in the Solar System, and
Speaker 6: they're gonna collide with each other. I mean, sure, they're
Speaker 6: in the Solar System together because of the gravity well
Speaker 6: of the Sun, but the fact that they're colliding with
Speaker 6: each other as opposed to not colliding, it's mostly just
Speaker 6: kind of look right, Yeah.
Speaker 1: It's gravity plus chance. It's possible to have a cluster
Speaker 1: where galaxies like ours and Andromeda don't collide until later on.
Speaker 1: Eventually everything is going to collide and it's all going
Speaker 1: to collapse into one super massive black hole. So it's
Speaker 1: really just a waiting game.
Speaker 6: But the collision that's going to happen in four and
Speaker 6: a half billion years, that's basically luck, right, It's not
Speaker 6: like it's inevitable, like if our galaxy was moving a
Speaker 6: few degrees in another direction, or to the right or
Speaker 6: to the left, we wouldn't be colliding with Andromeda, would we.
Speaker 1: Yeah, that's right. If you changed 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: now 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 6: M and So the reason we're worried about Andromeda and
Speaker 6: not other galaxies is because the other galaxies are further away,
Speaker 6: and those are definitely moving away from us because of
Speaker 6: dark energy, or are some of them potentially getting closer
Speaker 6: 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. Galaxy clusters are like the
Speaker 1: biggest thing that have that property. Anything that's larger than that,
Speaker 1: what we call a supercluster, is probably too big and
Speaker 1: too spread out for gravity to hold itself together, and
Speaker 1: dark energy is going to win. So that's sort of
Speaker 1: the tipping point. So anything that's in our galaxy cluster
Speaker 1: is eventually going to collapse. Into one big super massive
Speaker 1: black hole, and we're talking very very far in the.
Speaker 6: Future unless dark energy changes, right, Yes, like if it accelerates,
Speaker 6: then it's going to get a little more crowded, but
Speaker 6: it or if it like weekends, things might get a
Speaker 6: 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 6: Right, that's what I meant. I meant the opposite of
Speaker 6: what I said.
Speaker 1: But you're definitely right on the conceptual part, which is
Speaker 1: that we don't know what dark energy is or what
Speaker 1: it's going to do, and we can't really predict it.
Speaker 1: So this is assuming a naive extrapolation of dark energy,
Speaker 1: which is basically all we can do at this point.
Speaker 6: All Right, so we're in a collision course with Andromeda.
Speaker 6: 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 6: I guess how far apart are they? Like how far
Speaker 6: is there are year's neighbor?
Speaker 1: So our nearest neighbor is light years away, right, the
Speaker 1: closest star to us almost four light years away, and
Speaker 1: the Sun is the tiny fraction of a light year wide.
Speaker 1: I mean, if you shrink, for example, the Sun down
Speaker 1: to the size of a tennis ball that you could
Speaker 1: hold in your hand, then the nearest neighbor star would
Speaker 1: be four or five thousand miles away.
Speaker 6: 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 6: But I guess how wide is the sphere of influence
Speaker 6: of something like the Sun, Like how close do you
Speaker 6: 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 Petra's question 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?
Speaker 1: Are right? Because near misses can destabilize things, and we
Speaker 1: know that already in our galaxy because other stars are
Speaker 1: moving relative to the Sun. Sometimes they come closer, sometimes
Speaker 1: they come further away, and that can distort the orbits
Speaker 1: of stuff in our Solar system. So it's not a clear,
Speaker 1: crisp answer. It's not like there's a certain distance within
Speaker 1: which something happens and out of which nothing happens. It's gradual, right.
Speaker 1: The closer it comes, the greater the gravitational distortion.
Speaker 6: But I guess maybe it depends on how unstable our
Speaker 6: orbit is or how fragile our orbit is. Do you
Speaker 6: have a sense of how precarious are a path around
Speaker 6: the Sun is? Like if I bring in another Sun,
Speaker 6: I don't know, a few million miles away, is it
Speaker 6: going to affect us and kick us out of the
Speaker 6: Solar System or maybe cause us to fall into the Sun,
Speaker 6: 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 end fluence the Earth's orbit that makes
Speaker 1: its 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 6: Oh wait, wait, wait, so this is a star that's
Speaker 6: gonna come within one twenty fifth of the nearest star. Yeah,
Speaker 6: would it becomes the nearest star if it's coming close
Speaker 6: to us?
Speaker 1: Yeah, that's just for scale. Our current near stars four
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 6: How far in the future, in about one and a
Speaker 6: half million years. 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 6: And this is a star that's like traveling through space
Speaker 6: relative to us, or are we traveling close to it?
Speaker 6: You know what I mean? Like, is this an anomaly
Speaker 6: or in our quiet neighborhood or is it all part
Speaker 6: 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 6: And what do scientists predict this is going to happen
Speaker 6: when the start flies close to us? Is it gonna
Speaker 6: 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: and 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 nearby 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 come barreling
Speaker 1: into the inner Solar System, where they could become very
Speaker 1: high speed, very dangerous comets that could impact on the Earth.
Speaker 6: WHOA, but it maybe it might get lucky not get
Speaker 6: hit by, right, because even the space between us and
Speaker 6: the Sun is huge.
Speaker 1: Yeah, absolutely, we might get lucky, and we could get
Speaker 1: protected by Jupiter. Right, Jupiter has a lot of gravity
Speaker 1: and it tends to shield the inner Solar System by
Speaker 1: pulling these things towards it. Like when comet Shoemaker Levey
Speaker 1: came through the Solar System in the nineties, it impacted
Speaker 1: on Jupiter and that wasn't an accident. Not only is
Speaker 1: Jupiter just a much bigger target, but it has that gravity.
Speaker 1: But it's not a die you want to roll. It's
Speaker 1: sort of like playing cosmic Russian Roulette. You know, if
Speaker 1: a star comes by and dislodges a lot of oork
Speaker 1: cloud objects tens millions even for example, then we're gonna
Speaker 1: have to get lucky a lot of times to avoid
Speaker 1: being hit. So that's the most likely scenario for Glease,
Speaker 1: and also for the collision between Andromeda and the Milky Way,
Speaker 1: that our ort cloud gets perturbed.
Speaker 6: Well well, but I guess what is the scenario that's
Speaker 6: going to happen when we coll but Andrameda. Are we
Speaker 6: going to see a lot of these stars flying as
Speaker 6: close as Glee or is it going to be worse
Speaker 6: because I imagine, you know, the nearest star to class
Speaker 6: is pretty far away, but you know, we're colliding with
Speaker 6: a cloud of one hundred billion stars. Maybe that increases
Speaker 6: 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. Even though there are a lot of them,
Speaker 1: there are also very very spread out.
Speaker 6: No, should we just think you're word for it, or
Speaker 6: should maybe one of you guys get on the computer
Speaker 6: 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 6: I don't know. I like to plan ahead as you know. No,
Speaker 6: 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 Andrama and
Speaker 1: the dark matter between us and them. So we could
Speaker 1: do a calculation and give you a number, but it's
Speaker 1: gonna be different next year, and it's gonna be different
Speaker 1: in a million years, it's gonna be different in a
Speaker 1: billion years.
Speaker 6: Well, I mean, you don't need to predict what's going
Speaker 6: to happen exactly, but could you maybe get a statistical sense,
Speaker 6: Like if I take a cloud of stars like the
Speaker 6: Andromeda galaxy, and you take a cloud of stars like
Speaker 6: the the Milky Way galaxy, and you smash them into
Speaker 6: each other at the speed are going what are the
Speaker 6: chances or how likely or you know, how often would
Speaker 6: 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 6: All right, Well, then the answer for Petra is hopefully
Speaker 6: not nothing bad will happen. Daniel doesn't think.
Speaker 1: Don't worry too much about Petra. Zombies are much more likely.
Speaker 6: Yeah, don't collide with any zombies if you can't, especially
Speaker 6: when it's with teeth.
Speaker 1: But keep working on those intervals. That's going to save
Speaker 1: you in the end times.
Speaker 6: That's right. Bring your math book whenever you go out
Speaker 6: foraging for you know, particle colliders to start your fire.
Speaker 1: Or do what my dad did. Become a blacksmith and
Speaker 1: make your own weapons.
Speaker 6: Oh yeah, that's a good suggestion. Or just go to
Speaker 6: Daniel's garage and you know, steal some of those swords.
Speaker 1: I wouldn't recommend that. That's pretty well protected.
Speaker 6: By math. If you come within ten meters, you'll be
Speaker 6: faced with some physics questions, or you could just blast
Speaker 6: the podcast out in speakers. They'll keep every one away.
Speaker 5: All right.
Speaker 6: Let's get to our other questions here today, and we
Speaker 6: have some questions about extreme forces in the universe, and
Speaker 6: about what kind of air are we all breathing? So
Speaker 6: we'll dig into those, but first let's take a quick break.
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Speaker 1: When you pop a piece of cheese into your mouth
Speaker 1: or enjoy a rich spoonful of Greek yogurt, you're probably
Speaker 1: not thinking about the environmental impact of each and every bite,
Speaker 1: but the people in the dairy industry are. US Dairy
Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse
Speaker 1: gas neutral by twenty to fifty. That's why they're working
Speaker 1: hard at every day to find new ways to reduce waste,
Speaker 1: conserve natural resources, and drive down greenhouse gas emissions. Take water,
Speaker 1: for example, most dairy farms reuse water up to four
Speaker 1: times the same water cools the milk, cleans equipment, washes
Speaker 1: the barn, and irrigates the crops. How is US dairy
Speaker 1: tackling greenhouse gases? Many farms use anaerobic digestors that turn
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Speaker 1: the latest practices and innovations to provide the nutrient dense
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Speaker 1: us dairy dot com slash sustainability to learn more.
Speaker 6: All right, we're answering listener questions, and our second question
Speaker 6: comes from Dirk, who comes from the planet Earth.
Speaker 1: I guess probably we hope so, no, we hope not.
Speaker 6: Yeah, Hi Daniel and Jorge.
Speaker 5: So I have a question about extreme forces. I know
Speaker 5: gravity is one of the weakest forces in nature, but
Speaker 5: it seems like there's no limit to how much gravity
Speaker 5: there can be, and once you have enough of it,
Speaker 5: an event horizon is formed and a black hole is made.
Speaker 5: Even then more maths can be added and gravity will
Speaker 5: continue to increase. Can this be done with any of
Speaker 5: the other forces? Like can a magnetic field become so
Speaker 5: strong that it forms its own kind of event horizon?
Speaker 5: Or is there a limit that prevents the other forces
Speaker 5: from increasing infinitely? Thank you?
Speaker 6: All right, interesting question. I guess the question is how
Speaker 6: extreme can other forces get? Can you make like a
Speaker 6: magnetic black hole or a weak black hole.
Speaker 1: Yeah, super fun question, really great to think about, and
Speaker 1: I love the sort of philosophy behind this question. Trying
Speaker 1: to make connections between forces and trying to understand the
Speaker 1: differences between ideas. This is really how you make progress
Speaker 1: in physics. How you build to consist model in your head,
Speaker 1: try to understand where that model doesn't work and where
Speaker 1: the pits don't fit together, and then try to understand
Speaker 1: how they can possibly click together. So kudos to you,
Speaker 1: Derek for thinking about it this way and for asking
Speaker 1: this great question.
Speaker 6: All Right, the question is Derek is wondering, like, we
Speaker 6: know that a black hole happens when you gravity gets
Speaker 6: so intense that it becomes basically a black hole with
Speaker 6: an event horizon. Can that sort of thing happen with
Speaker 6: the other forces in nature, like electromagnetism or the weak
Speaker 6: force or the strong force. Can you get a situation
Speaker 6: where the magnetic force is so strong it can maybe
Speaker 6: 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 mass 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: It's very intuitive, but remember that gravity is not actually
Speaker 1: a force. It's Our understanding of gravity today is that
Speaker 1: it represents the curvature of space time itself, and in
Speaker 1: many ways that's equivalent. Like most of the time, you
Speaker 1: can think about the curvature of space time and from
Speaker 1: that you can get exactly the same behavior that Newton
Speaker 1: would have predicted, but it's also crucially different in many respects.
Speaker 1: There's lots of things that the curvature of space time
Speaker 1: can do that the simple force of gravity cannot do.
Speaker 1: And form an event horizon is one of those things.
Speaker 1: So Einstein's reconception of gravity as a curvature of space
Speaker 1: time describes all of Newton's physics, but also more than that,
Speaker 1: it doesn't just reformulate gravity as another way to think
Speaker 1: about it, it adds new capacity to gravity. New things
Speaker 1: that it can do. And so the force description of
Speaker 1: gravity cannot create an event horizon, but the curvature description
Speaker 1: of gravity can create event horizons. And so the other forces,
Speaker 1: which can't be described in terms of curvature, can't create
Speaker 1: event horizons. That's not something a force can do. Only
Speaker 1: spacetime curvature can do that.
Speaker 6: Well, I guess I might ask, are you sure about that?
Speaker 6: Couldn't you define the event horizon as the point at
Speaker 6: which the force of gravity is so strong that nothing
Speaker 6: 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 a black hole can exist.
Speaker 1: The reason we have event horizons, the reason that curvature
Speaker 1: can do this and the forces cannot, is that curvature
Speaker 1: does something to space. It changes the shape of space,
Speaker 1: like the relationship between points. So you can think about
Speaker 1: it as like a region from which even a photon
Speaker 1: cannot escape, right, And that again is something gravity can do.
Speaker 1: But you can't do that with magnetism or electric force
Speaker 1: or the strong force.
Speaker 6: Well, I guess what I mean is, like you know,
Speaker 6: for example, you might say that the Earth has an
Speaker 6: event horizon, right, Like there's a point and a velocity
Speaker 6: at which you can escape to Earth, and there's a
Speaker 6: point at which you cannot escape Earth, right, So maybe
Speaker 6: you might be able to call that the event horizon
Speaker 6: of the Earth gravity, black holes, event horizon. It's just that.
Speaker 6: But taking to the extreme where you're talking about not
Speaker 6: even light being able to escape, I wonder if you
Speaker 6: can do that the same with a magnetic field or
Speaker 6: like a magnetic force, Like, is there a point at
Speaker 6: which not even like a super fast moving charged particle
Speaker 6: will escape the attractive force that something has Electromygnetically, I.
Speaker 1: Mean, you can definitely form bound states right, Like the
Speaker 1: Moon is bound to the Earth gravitationally, but it can
Speaker 1: still escape, right, Or photons from the Moon can definitely
Speaker 1: escape the gravitational system. And that's not just like a
Speaker 1: difference in degree, it's a difference in kind. Right. The
Speaker 1: inside of an event horizon really is cut off from
Speaker 1: the rest of the universe. Nothing that happens there can
Speaker 1: influence anything that happens outside the universe, whereas things that
Speaker 1: happen on Earth can always influence things far away. It
Speaker 1: just takes some time. So it's a question of like causality,
Speaker 1: like are these things linked or not? Can one area
Speaker 1: of space affect another? You can definitely attract things together,
Speaker 1: and they can even be stuck together, and they can
Speaker 1: be stable, and they can even last for millions or
Speaker 1: billions of years or configurations like the proton might last forever,
Speaker 1: but you know, the quarks inside the proton could still
Speaker 1: potentially escape you give them enough energy. It's a bound state.
Speaker 1: That's not the same thing as an event horizon.
Speaker 6: But could you say that, like a charged ball ofity
Speaker 6: has an escape velocity to it and a point at
Speaker 6: 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. It 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 6: But I guess light is an electrically neutral right, Yeah,
Speaker 6: So I wonder if you can envision, like, is there
Speaker 6: a ball of charge. They can be so intense that
Speaker 6: not even a core going at the speed of light
Speaker 6: can escape it. You maybe call that the event horizon
Speaker 6: 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 6: Right, Well, of course I know this, but like, if
Speaker 6: it was moving at the speed of light, is there
Speaker 6: a point we're closing on nine point nine nine nine
Speaker 6: percent of yeah, the speed of light. Is there an
Speaker 6: event horizon for 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: you 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 try crap an electron forever. You
Speaker 1: can't create an event horizon using electric charge. You could
Speaker 1: always just give that electron more energy and it would
Speaker 1: escape your ball of charge, no matter how big it.
Speaker 6: Is all right, So then the answer for Derek is no,
Speaker 6: 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 and 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,
Speaker 1: So like the strong force can create really really strong
Speaker 1: bound states, but then neutrinos ignore it, right, they would
Speaker 1: just fly right through it. So in that sense, an
Speaker 1: event horizon for like electromagnetism wouldn't really be an event
Speaker 1: horizon even if you could make one, because some particles
Speaker 1: ignore it. The amazing, awesome thing about gravity is that
Speaker 1: nothing can ignore it. Gravity is just linked to energy.
Speaker 1: So anything that has energy, we just basically anything in
Speaker 1: the way we conceive of it is affected by gravity.
Speaker 1: It's inescapable.
Speaker 6: Oh all right, Hm, I'm still wondering, like could you
Speaker 6: make that calculation? Like what did you take an electron
Speaker 6: give it this speed of light. Could you use that
Speaker 6: to compute a positive ball of charge strong enough for
Speaker 6: 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 just
Speaker 1: like infinity versus infinity.
Speaker 6: Well, I guess what I mean is like, when you
Speaker 6: compute the scape velocity of something escaping Earth, you're not
Speaker 6: actually using the relativistic equations, right, You're just kind of
Speaker 6: 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 6: Right. But so let's say I do that for an
Speaker 6: electron and I give it the speed of light. Could
Speaker 6: I compute an event horizon, even though maybe it's not realistic,
Speaker 6: but it 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 6: Yeah, just like when we compute the scape velocity of
Speaker 6: 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 it 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 6: So would that mean that my electric black hole is
Speaker 6: infinitely or infinitely small.
Speaker 1: It would be infinitely charged.
Speaker 6: Oh does it have to be infinitely charged or could
Speaker 6: 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
Speaker 1: orbit but this is like a mean distance from the
Speaker 1: center for the ground state, and so that effectively limits
Speaker 1: how powerful these things can get. Like there's a reason
Speaker 1: the hydrogen atom has a ground state and the electron
Speaker 1: is not closer to it. It can't settle any closer,
Speaker 1: and that effectively bounds like how strong the force can get.
Speaker 6: Oh Man, So you're saying 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 6: So then it would be sort of like a black hole,
Speaker 6: but in 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 6: There'd be holes in our black hole is basically.
Speaker 1: What you're seeing.
Speaker 6: Yeah, exactly, all right, Well that's an interesting answer for Derek.
Speaker 6: Now let's get to our last question of today, and
Speaker 6: it's about the air we breathe and where does part
Speaker 6: of it come from? So let's dig into that question.
Speaker 6: But first let's take a quick break.
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Speaker 2: journey takes you, you'll enjoy remarkable rewards, including a free
Speaker 2: checked bag and two times the miles on every United purchase.
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Speaker 2: at hotels, so every experience is even more rewarding. Plus,
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Speaker 1: When you pop a piece of cheese into your mouth
Speaker 1: or enjoy a rich spoonful of Greek yogurt, you're probably
Speaker 1: not thinking about the environmental impact of each and every bite,
Speaker 1: but the people in the dairy industry are. US Dairy
Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse
Speaker 1: gas neutral by twenty to fifty. That's why they're working
Speaker 1: hard every day to find new ways to reduce waste,
Speaker 1: conserve natural resources, and drive down greenhouse gas emissions. Take water,
Speaker 1: for example, most dairy farms reuse water up to four
Speaker 1: times the same water cools the milk, cleans equipment, washes
Speaker 1: the barn, and irrigates the crops. How is US dairy
Speaker 1: tackling greenhouse gases? Many farms use anaerobic digestors that turn
Speaker 1: the methane from maneuver into renewable energy that can power farms, towns,
Speaker 1: and electric cars. So the next time you grab a
Speaker 1: slice of pizza or lick an ice cream cone, know
Speaker 1: that dairy farmers and processors around the country are using
Speaker 1: the latest practices and innovations to provide the nutrient dense
Speaker 1: dairy products we love with less of an impact. Visit
Speaker 1: us dairy dot com slash sustainability to learn more.
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Speaker 6: We're answering listener questions here today, and our last question
Speaker 6: comes from Steve Parrin from Quebec.
Speaker 5: Hi, Daniel and Jorge, this is Steve Pagan from Quebec, Canada.
Speaker 5: My question is where is all the nitrogen in our
Speaker 5: atmosphere coming from?
Speaker 1: And what role does it play? Amazing podcast guys, I
Speaker 1: love it, Thank you?
Speaker 6: All right, A pretty straightforward question here, Where does all
Speaker 6: the nitrogen in our atmosphere come from? And what role
Speaker 6: 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 like gulping oxygen, but it's mostly
Speaker 1: nitrogen that you're breathing in, which is kind of weird.
Speaker 6: WHOA, what do you mean mostly? What are the percentages?
Speaker 1: It's almost eighty percent of the air is nitrogen.
Speaker 6: Eighty percent by like a volume mass or atoms.
Speaker 1: It's seventy eight percent by mass.
Speaker 6: Oh, and how much of it is oxygen? So it's
Speaker 6: like most of the air is nitrogen.
Speaker 1: It's seventy eight percent by quantity.
Speaker 6: Meaning by volume or what do you mean by quantity
Speaker 6: 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 6: WHOA, 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 6: 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 lasted 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 6: But I guess a deeper question is where did it
Speaker 6: all come from originally? Like it just got form inside
Speaker 6: the Sun like all the other heavy elements in previous
Speaker 6: 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 the
Speaker 1: very very early universe, tiny tiny trace amounts of helium,
Speaker 1: and then you have to wait for stars to be
Speaker 1: born hundreds of millions of years later to turn that
Speaker 1: hydrogen into heavier stuff. And so that nitrogen that you're
Speaker 1: breathing right now. Was made at the heart of stars
Speaker 1: previous generation, which burned created that nitrogen inside them, and
Speaker 1: then blew up and spread those heavier elements, including nitrogen
Speaker 1: and iron and copper and on carbon and all that
Speaker 1: good stuff throughout the galaxy, and then that re coalesced
Speaker 1: into our solar system. So all the nitrogen and the
Speaker 1: iron and all that stuff in our bodies and in
Speaker 1: the air and in the Earth was made by a
Speaker 1: different star that no longer exists whoa.
Speaker 6: And it was made at the core of that previous star,
Speaker 6: or when it exploded.
Speaker 1: The stuff that's iron or lighter was made to the
Speaker 1: core of that star. It's made by fusion, because when
Speaker 1: you fuse two lighter elements together, you release energy. But
Speaker 1: that's only true up to making iron. Beyond iron, when
Speaker 1: you fuse stuff together, it costs energy. So if a
Speaker 1: star starts to do that, it begins to dim and
Speaker 1: like steals away the energy. And stars need that energy
Speaker 1: to survive because they're fighting against gravity. Gravity is trying
Speaker 1: to compress them down into a black hole. And the
Speaker 1: only reason the star survives for millions or billions of
Speaker 1: years is that radiation pressure outwards. That's created by the
Speaker 1: energy released by fusion. If that goes away, then the
Speaker 1: star stars to collapse, and so stars can't make a
Speaker 1: lot of the heavier elements above iron. For that, you
Speaker 1: need either the death of the star, the supernova which
Speaker 1: has super dense conditions capable of creating those heavier elements,
Speaker 1: or things later on like collisions of neutron stars to
Speaker 1: create the heaviest elements. But nitrogen is made in the
Speaker 1: heart of those stars during normal fusion.
Speaker 6: So we're basically breathing dead stars.
Speaker 1: Every time you take a breath, it's a gift from
Speaker 1: those stars.
Speaker 6: You're basically breathing zombie star.
Speaker 1: Yes, exactly, zombie star brains. Take a deep breath.
Speaker 6: Yeah, smells delicious, smells like brains. So the previous star
Speaker 6: made the It was floating around just like all the
Speaker 6: hydrogen and carbon and dust and rocks that was made
Speaker 6: by previous stars when our Sun started burning, And then
Speaker 6: how did it end up on Earth or is it
Speaker 6: spread out all around the Solar System.
Speaker 1: It's all over the sol 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. So the early Earth was blasted clean.
Speaker 1: Essentially it was just a bare rock because of the
Speaker 1: solar radiation. But then it got a second atmosphere due
Speaker 1: to collisions and also because of nitrogen and other gases
Speaker 1: trapped inside the Earth which escaped out due to like volcanoes.
Speaker 1: You know, you have a lot of these gases in
Speaker 1: the early Earth, and as the Earth is settling, the
Speaker 1: heavy stuff goes down to the core and the lighter
Speaker 1: stuff rises in the mantle, and then some of that
Speaker 1: escapes through cracks in the Earth. So volcanoes and the
Speaker 1: bombardment of asteroids created our second atmosphere, which was mostly
Speaker 1: nitrogen and carbon dioxide. So that's where the nitrogen comes.
Speaker 6: From, and then eventually we got oxygen. But I guess
Speaker 6: the second part of the's question is what role does
Speaker 6: nitrogen play? Like do our bodies need nitrogen or do
Speaker 6: we just ignore it? Mostly?
Speaker 1: Yeah, it's definitely not inert. Nitrogen plays a really important
Speaker 1: role in the life cycle here on Earth. Like plants
Speaker 1: need nitrogen. It's a crucial part of a lot of
Speaker 1: amino acids, and so in order for plants to grow,
Speaker 1: you need nitrogen in the soil, a big component of
Speaker 1: like fertilizer that people are constantly putting onto their plants.
Speaker 1: Farmers impour huge amounts of it. The reason you put
Speaker 1: manure on fields is that it has nitrogen in it
Speaker 1: and other stuff. So plants need this nitrogen in order
Speaker 1: to grow. And there are these bacteria that will breathe
Speaker 1: the nitrogen from the atmosphere and then basically make it
Speaker 1: available for the plants. So there's a whole complicated nitrogen
Speaker 1: cycle that involves like these nitrogen fixing bacteria and then
Speaker 1: plants using it to grow, and animals eating it and
Speaker 1: then pooping it back out into the ground. And it's
Speaker 1: very complex cycle, but it's definitely not inert. It's a
Speaker 1: huge part of life on.
Speaker 6: Earth right right. And I just want to take a
Speaker 6: quick moment here to note that you were the first
Speaker 6: one to bring up poop in this episode, not me.
Speaker 1: Is that something you keep track of who says poop first?
Speaker 6: I'm just saying sometimes they get, you know, accused of
Speaker 6: cultural language podcast down.
Speaker 1: Yeah, well, you know that's the conversation we have at
Speaker 1: my house all the time because my wife works on
Speaker 1: the gut microbiome, like literally, what's happening inside your guts?
Speaker 1: And so the kids are always timing, like how long
Speaker 1: till mom brings up poop at the dinner table? Oh boy,
Speaker 1: and it's never very long.
Speaker 6: May should just call it nigrogen instead of poop nigrogen
Speaker 6: rich content. They'll spare your appetites.
Speaker 1: We're just fertilizing a conversation.
Speaker 6: Yeah, you just want to make it more fregrant. But
Speaker 6: I guess why is nigrogen important and biological processes? Is
Speaker 6: it something there's something special about that molecule, you know,
Speaker 6: because carbon as some special things about it that make
Speaker 6: it kind of crucial to life? Is legigend 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 to be a Wikipedia later,
Speaker 1: I mean, na gigen is already at the edge of
Speaker 1: my ability to think about things. There's so many protons
Speaker 1: there it's crazy. And then you have it connected with.
Speaker 6: Another chem your brain would explode.
Speaker 1: Yeah, exactly, too many integrals from me.
Speaker 6: For as a physicist zombie. You just have to throw
Speaker 6: some chemistry questions at them, absolutely, and then their brains
Speaker 6: 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?
Speaker 9: Time?
Speaker 1: Right?
Speaker 3: Right?
Speaker 6: Hey Daniel, what's up? Regardless number big Welcome to Jorge
Speaker 6: explains the universe. All right, Well that's the answer for Steve,
Speaker 6: which is that the nigogen we're all breathing, eighty percent
Speaker 6: of the air we're breathing, came from a debt previous
Speaker 6: star in our solar system. Then it got formed with
Speaker 6: the rest of the Earth and the rocks and the
Speaker 6: other elements, and that's how we're breathing it today. That's right,
Speaker 6: Possibly from comets, possibly from the Earth burping.
Speaker 1: Yeah, exactly. And there have been some people doing really
Speaker 1: interesting studies to try to understand exactly where this nitrogen
Speaker 1: came from, because not all nitrogen is the same, some
Speaker 1: of them have different isotope ratios, and you can tell
Speaker 1: like was it formed in the Outer Solar System or
Speaker 1: the Inner Solar System the molecules not the pure nitrogen
Speaker 1: which was made in the stars. And so there are
Speaker 1: these studies that tell us that some of the nitrogen
Speaker 1: on Earth came from the Inner Solar System and some
Speaker 1: definitely came from the Outer Solar System. So it's a
Speaker 1: similar question to like where did our water come from?
Speaker 6: All right, well, three awesome quiesce here today. Thanks to
Speaker 6: 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 Danielanjorge dot com. You'll
Speaker 1: definitely hear back from us.
Speaker 6: We hope you enjoyed that. Thanks for listening, See you
Speaker 6: next time.
Speaker 1: For more science and curiosity, come find us on social
Speaker 1: media where we answer questions and post videos. We're on Twitter, Discorg, Instant,
Speaker 1: and now TikTok. Thanks for listening and remember that Daniel
Speaker 1: and Jorge Explain the Universe is a production of iHeartRadio.
Speaker 1: For more podcasts from iHeartRadio, visit the iHeartRadio app Apple
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