Listener Questions #12

Daniel and Kelly answer questions about neutrons, bananas and Jupiter and find a secret theme that links them all! See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

  This is an iHeart Podcast. Guaranteed Human.

• 0:04Speaker 01

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• 0:49Speaker 01

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• 1:18Daniel Whiteson?

  Why are neutrons so complicated? And why is white chocolate not more widely hated?

• 1:24Kelly Weinersmith?

  Are the bananas we eat all the same? Can we save them from that fungal strain?

• 1:29Daniel Whiteson?

  Is Jupiter really only made of gas? It's definitely got a lot of mess.

• 1:34Kelly Weinersmith?

  Biology, physics, archaeology, forestry. Thanks for not asking about chemistry.

• 1:41Daniel Whiteson?

  What diseases do you get from your cat? Well, we'll find the answers to all of that.

• 1:46Kelly Weinersmith?

  Whatever questions keep you up at night, Daniel and Kelly's answers will make it right.

• 1:50Daniel Whiteson?

  Welcome to another Listener Questions episode on Daniel and Kelly's extraordinary universe.

• 2:09Kelly Weinersmith?

  Hello, I'm Kelly Weinersmith. I study parasites and space.

• 2:13Daniel Whiteson?

  And you are surprisingly good at limericks.

• 2:15Kelly Weinersmith?

  Well, I don't know about that. I gave a talk in Kentucky and a woman who is a poet was invited. And she gave a poem about our book. And she encouraged me to be bolder about poetry and not so self-conscious. And I know it's not good, my rhymes, but I have so much fun. And I'm like, that's kind of the point for me. For me, that's the point.

• 2:39Daniel Whiteson?

  Well, I'm Daniel. I'm a particle physicist. I don't pretend to be a poet, but I think the universe is kind of poetic.

• 2:46Kelly Weinersmith?

  Oh, see, I think you're a poet in your own way, because you say very poetic things.

• 2:52Daniel Whiteson?

  Well, if being corny and curious about the universe counts as being poetic, then put me on that list.

• 2:57Kelly Weinersmith?

  It's a dad kind of poetry.

• 3:00Daniel Whiteson?

  Dad poetry. Oh, my gosh. Science dad poetry. That is a new genre. We are pioneering here. Science parent poetry, really.

• 3:08Kelly Weinersmith?

  Yes. Well, you might ask yourself, why would Kelly make her poems public? I don't really know. I have confidence beyond what I ought to. But you know, there are other questions out there, and our listeners have loads of them.

• 3:22Daniel Whiteson?

  Questions deeper than Kelly's ability to rhyme. We love hearing your questions about the universe. How did it begin? How was it going to end? Was it all mean? How does it come together to explain everything we are and everything we eat and all the poems we listen to? If you have questions about the nature of the universe and you can't find answers, you've been Googling, you've been asking your neighbors, you don't know any physicists or parasitologists yourself, please write into us to [email protected]. We love, love, love to hear from you, and you will definitely hear from us.

• 3:55Kelly Weinersmith?

  And everybody should have a parasitologist and a physicist in their lives. And we are here for you.

• 4:00Daniel Whiteson?

  That's right. We are filling that hole you didn't know you had in your life.

• 4:06Daniel Whiteson?

  And so today, we have a bunch of really fun questions about neutrons, about bananas, and about Jupiter. And there's a theme that's going to tie them all together. We'll reveal it at the end.

• 4:16Kelly Weinersmith?

  Oh, Daniel's going to be revealing this to Kelly, too, because I didn't see a theme while I was reading our outline. Can't wait to find out.

• 4:24Daniel Whiteson?

  This first question is from Scott Lewis, who thought that neutrons also needed some Daniel and Kelly love after hearing our episode about protons.

• 4:31Speaker 03

  Hi, Kelly and Daniel. There've been a number of articles lately discussing the internal complexity of the proton and everything we are learning about it. One article went so far as to describe it as "the most complicated thing you can possibly imagine." I've read of unusual tetrachoric configurations and other weird things that show up in the colliders from time to time. Is the internal structure of a neutron similarly complex? Do we know less about the guts of a neutron? And if so, is there a reason why they are perhaps more difficult to study? Thank you for everything you guys do. Great job on the program.

• 5:15Kelly Weinersmith?

  This is a great question. And you know, Daniel, whenever I hear about neutrons, I think about one of those disaster movies with John Cusack in it, where the world was like falling apart because the neutrons had mutated.

• 5:27Kelly Weinersmith?

  Yeah, I know. I almost walked out of that movie. I loved John Cusack as a child of the 80s, you know?

• 5:34Daniel Whiteson?

  You can say anything, but don't say anything about neutrons mutating.

• 5:37Kelly Weinersmith?

  That's right. That's a line for me, a line. But I gotta say, I don't really understand neutrons very well. So let's start at the beginning. What are neutrons? And hopefully, by the end, I'll be convinced that they won't mutate and I don't have to worry about the world being destroyed.

• 5:51Daniel Whiteson?

  Well, I agree with Scott. Neutrons are just as fascinating, if not more so, than protons. And they don't get as much attention because we don't think of them as the building blocks of matter. But they really are. They're essential. Without neutrons, we wouldn't have big, complicated atoms that you need for biology and chemistry and bananas, for example. But protons and neutrons are very closely related. Both of them are made of the same fundamental objects, just different amounts. Of them. So a proton is made of two up quarks and a down quark. And so the up quark is charged two thirds and the down quark is charged minus one third. So you add two up quarks and a down quark, you get a total charge of one. That's the proton. If you switch one of those up quarks for a down quark,

• 6:33Daniel Whiteson?

  now you have one up quark with charge two thirds and two down quarks with charge minus one third each. You get a neutron because it's neutral and has zero electric charge. So two downs and an up neutron, two ups and a down proton.

• 6:47Kelly Weinersmith?

  Got it. So usually on this show, you hear me complain about how bad physicists are at naming things.

• 6:53Daniel Whiteson?

  Because we are.

• 6:54Kelly Weinersmith?

  Exactly. Yeah. I'm making an accurate observation. But I love that y'all have named the thing that holds it all together gluons. And I'm assuming that's because it sounds like glue, right?

• 7:06Daniel Whiteson?

  Well, the gluons aren't very sticky. Yes.

• 7:08Kelly Weinersmith?

  Yeah.

• 7:08Daniel Whiteson?

  They do hold these things together. And so up quarks and down quarks are super fascinating because they're similar to other particles we know, like electrons. But they also feel another force, the strong nuclear force. So they're charged. We talked about them having two thirds or negative one third charge. So they feel electromagnetism. They can shoot off photons. They feel electric fields. But there's another field in the universe that they feel that electrons ignore. And that's the color field of the strong nuclear force. And vibrations of that field, there are actually eight different ones, are called gluons. And so gluons are the mediator of the strong force, the way photons are the mediator of the electromagnetic force. It's just one of the things the universe can do.

• 7:51Daniel Whiteson?

  And electrons have zero color charge, so they just fly through and ignore it. The way neutrinos, for example, ignore electric fields. But quarks, they feel all of the fields, the weak field, the strong field, the electromagnetic field. They feel all of them. And the strong field is the strongest one. And so it binds these particles together very, very tightly. So the proton and neutron are both bound together using gluons.

• 8:13Kelly Weinersmith?

  And is there a history behind gluons that's going to like, make me think you all aren't clever? Or was it called gluons because it like seems to glue things together?

• 8:22Daniel Whiteson?

  No, we're called the gluons because they glue the nucleus together. Exactly. And there's a whole fascinating history about the discovery of gluons and the personalities involved. It was a really interesting moment with fascinating history, but basically every discovery in particle physics has like cool personalities and controversies.

• 8:38Kelly Weinersmith?

  You would say that as a permanent member of that community.

• 8:43Daniel Whiteson?

  They're not always positive stories, you know, there's like arguments and people peeing on other people's experiments and like, you know, these are human stories because, hey, physicists are people, you know, we're just curious about the universe and there are Nobel prizes at stake. So you don't always get the best side of everybody.

• 8:59Kelly Weinersmith?

  They sure smell like people. You walk up to them, you're like, yeah, you're a person. But anyway, okay, one day we should get the great story behind gluons, but let's talk about how neutrons decay.

• 9:08Daniel Whiteson?

  Yeah. So the fascinating thing that neutrons can do that protons do not do is that they decay. They don't last forever. You have a neutron out there in the universe just by itself. It's going to turn into a proton. And the way it does this is that one of those quarks, the D quark, turns into an up quark. So it goes from D to up. Now, it starts out as a D quark, which is charged negative one third, and becomes an up quark, which is charged two thirds. So to conserve electric charge, it has to emit a negatively charged particle. So it emits a W minus, which has charged negative one. So all the charges balance out. So this D quark emits a W minus and turns into an up quark, turning

• 9:50Daniel Whiteson?

  the neutron into a proton and then shooting off this W minus particle.

• 9:54Kelly Weinersmith?

  Okay. So neutron, when it becomes a proton, you get a proton and an electron that shoots off.

• 10:01Daniel Whiteson?

  You get a W minus, not an electron, but you're close because the W minus doesn't live for very long. It turns into an electron and an antineutrino.

• 10:10Kelly Weinersmith?

  Of course.

• 10:11Daniel Whiteson?

  That's basically the process is the neutron turns into a proton. In order to balance the charge, it has to carry along an electron eventually, right? Because you start with a neutron, it's zero charge. You end up with a proton with plus one and you need the electron with minus one to balance the electric charges. But the universe is not happy with that because the universe also conserves the number of. Electrons, like you can't just create electrons willy nilly. The universe keeps tabs on that. So if you create an electron, you also have to create an anti-electron. Or it turns out electron neutrinos also count. So if you create an electron and an anti-electron neutrino at the same time, then everything balances out. You've accounted for everything the universe cares about.

• 10:52Kelly Weinersmith?

  I think the up down quirks give me this maybe false sense of understanding what's going on because I just imagine an up arrow and a down arrow. And I'm like, oh, I got it. You just flip the down arrow. Now it's pointing up. But what does it mean to say it emits a W minus? Is it just like the change in energy gets expelled? And that's what it means to say emitting a W minus?

• 11:13Daniel Whiteson?

  We really do think about these things as a pair where the up on the top and the D on the bottom. And the way we think about it from a sort of theoretical point of view is that the W is the way to go up or down. So there's actually two Ws, the W plus and the W minus. If you want to go from the D to the U, you emit a W minus. If you want to go from the U to the D, you emit a W plus. So these are sort of like stair steps in order to go from one to the other. The sort of the same way around an atom, an electron can go up and down energy levels. And to do so, it either emits or absorbs a photon. These Ws change the state from a D to a U. And there is a connection to the sort of underlying theoretical structure, which we usually represent using these things called groups,

• 11:56Daniel Whiteson?

  where you can transform an object, but it stays within a little predefined set. That's called a group. And so it's deeply connected to the sort of group theory structure, which I think we should dig into sometime on the podcast.

• 12:06Kelly Weinersmith?

  Sure.

• 12:06Daniel Whiteson?

  But the basic version is that the up is sort of the higher state and the down is the lower state. But you can move between them using these Ws.

• 12:14Kelly Weinersmith?

  Okay, awesome. All right, I think I get that. Thank you. So you can go from neutron to proton, but protons don't decay into neutrons. Why do neutrons decay?

• 12:23Daniel Whiteson?

  Yeah, great question. Why do neutrons decay and protons don't? Well, neutrons have a higher mass than protons. And so when a neutron decays, it gives off a little bit of energy and turns into a proton. Why does a neutron have a higher mass than a proton? Well, remember, the mass of these guys comes from the bonds between the quarks. It's not because the neutron is made of heavier stuff than the protons. These up and down quarks have almost no mass, basically zero, compared to the mass of the proton and the neutron. All of the mass of these guys comes from the gluons, the arrangements of the particles. And so the neutron state, up, down, down, is a higher energy configuration than the up, up, down proton state. And so it's just like a higher energy level.

• 13:04Daniel Whiteson?

  The way like around an atom, you know, there's like the 52S state is a higher energy level than like the 2P or whatever. There's all these different energy levels and they have to do with the arrangements between the particles, the configurations. And so the strong nuclear force, super duper complicated, but this neutron state, the UDD state, is higher energy than the UUD. And so it can decay down. And that's what the universe does. It always starts with massive particles, which decay down into lighter particles. The proton can't decay because there's nothing lighter than the proton. Like you can't find a state that's lighter than the proton. If you turn that other D into a U, for example, it actually would be a higher energy state than the proton. So the proton is sort of like the bottom of the ladder, in the same way the electron is.

• 13:47Daniel Whiteson?

  The muon can decay into an electron and other stuff. Why doesn't the electron decay? Because there's nothing for it to decay into. It's the lightest particle and therefore it's stable. And we don't know that the proton is actually stable. We've just never seen it decay. And so we can estimate that its lifetime is super duper long because we've watched a bunch of protons for a long time to see if any of them decay and never seen a single one decay, which means either they're totally stable, like they live forever, or they live for such a long time that we just haven't seen one yet. And that lifetime would be like billions and billions of years. So neutrons are super fascinating because they actually do decay. So we can learn something about what's going on inside them.

• 14:26Kelly Weinersmith?

  So in the nucleus of an atom, you have the same number of protons and neutrons, but the number of protons isn't changing over time, but neutrons are decaying into protons. What's gonna happen? Are we eventually not gonna have enough neutrons for everything?

• 14:40Daniel Whiteson?

  Yeah, this is really amazing because remember we are talking about neutrons by themselves. A single neutron in the middle of space will decay in about 11 to 12 minutes. So you might be wondering, why isn't everything inside me? Why aren't all my neutrons turning into protons? And then like, you know, everything's going haywire. Because the neutron is stable if it's inside the atom. It's unstable and will decay into a proton when it's outside by itself. But inside the atom, all of its other neutron and proton buddies stabilize it. That's really weird, right? What's going on? Well, some really interesting strong force stuff is happening there. Because when the neutrons and the protons are together in the nucleus, they're not just like packed in like tennis balls. They're interacting with each other, right? These things are quarks with gluons holding them together,

• 15:25Daniel Whiteson?

  but they're not completely sealed off from anything else. If you're like on one side of the gluon, you might be closer to one of the quarks or closer to one of the other quarks. So you can actually feel the quarks inside the neutron if you're nearby it. And so the atom is not just like a bunch of tennis balls totally sealed off. They're interacting with each other. There's this little residual strong force. That's actually what holds the nucleus together.

• 15:46Kelly Weinersmith?

  Friends help you hold everything together.

• 15:49Daniel Whiteson?

  Yes, exactly. And so inside nucleus, neutrons can live a long, long time. Sometimes they can live forever. Like, take a carbon atom. Carbon has a bunch of neutrons in the nuclei. Those neutrons will live forever. You have a carbon atom, we think it could just sit in space for a zillion, zillion, zillion years. Other elements are not as stable, like uranium, for example, will break down. And one of the ways it does is through these kinds of decays. And so neutrons can either crack open your nucleus if they're not quite stable enough, or they can help it stay together. Like, the reason the nucleus stays together, all these protons, which otherwise are pushing each other apart, is because the neutrons are there in between to help stabilize it, to pull them together with the strong force and to keep the protons from pulling themselves apart.

• 16:33Daniel Whiteson?

  So neutrons are really the glue that holds the whole universe together.

• 16:36Kelly Weinersmith?

  I feel like you could write nerdy Hallmark cards.

• 16:41Daniel Whiteson?

  I love you and your neutrons.

• 16:42Kelly Weinersmith?

  That's right. You hold me together. You're my proton.

• 16:48Kelly Weinersmith?

  You keep me from decay. That's right.

• 16:53Daniel Whiteson?

  But there's also still a bunch of mysteries about the neutron. Like, we think we understand the basic story here. But, you know, particle physics nerds always want to drill down and say, do we really understand it? Let's make a bunch of really precise measurements in different ways and see if there's anything surprising. So there's this mystery right now in exactly how long the neutron does live.

• 17:14Kelly Weinersmith?

  How do we ask that question?

• 17:16Daniel Whiteson?

  So people came up with two very different ways to measure, like, how long does a neutron take to decay? There's the bottle method and the beam method. And the bottle method is pretty simple. It says, take a bunch of neutrons, cool them down so they're not flying around everywhere, put them in a bottle, and then just wait and see how many you have. Like, you know, plot them over time. The way we study radioactive decay or any kind of random process is you start with a bunch of them and you wait to see how long does it take until you have half as many? And that's the characteristic lifetime. And so that's what they do and they get a number. It's like 14 minutes and 39 seconds is the characteristic lifetime of a neutron. This is a really cool experiment they do in Los Alamos, New Mexico, actually, my hometown. And they have these ultra cold neutrons.

• 17:59Daniel Whiteson?

  They've chilled them down to like milli Kelvin. Inside this container they call the bathtub, that's like one meter in diameter. They just like fill it with neutrons and count them and then wait to see what happens. And so they get their number and, you know, these are serious dudes. They take it very seriously. They've accounted for all sorts of uncertainty. They've cross checks, whatever. They're very confident in their number. But there's another experiment, the beam experiment, and they don't get the same answer.

• 18:24Kelly Weinersmith?

  What? How much does it differ by?

• 18:26Daniel Whiteson?

  The beam experiment makes a neutron beam. And, you know, we said that neutrons decay into protons, right? So they had this clever idea like, oh, neutrons are actually really hard to count. The other guys had this complicated, sophisticated equipment to count neutrons. They're hard. Let's just count the protons. If neutrons are decaying into protons, let's just count the protons. And so they fly it through an electromagnetic field, filter out the protons and count those. And they get a different answer. They get a slightly longer answer by nine seconds. So instead of 14 minutes and 39 seconds, they get 14 minutes and 48 seconds. So they think neutrons live a little bit longer than the bathtub guys.

• 19:01Kelly Weinersmith?

  But don't you have to at least know how many neutrons you're starting with? Because if you get 10 protons, but you don't know how many neutrons you started with, how do you know the rate of decay?

• 19:11Daniel Whiteson?

  Yeah, good question. They know how many neutrons they've started with because they know how they produce the neutrons.

• 19:16Kelly Weinersmith?

  Okay.

• 19:16Daniel Whiteson?

  And so they think they've accounted for that. But you know, something is going on here. Like, it's the same process. They should get the same answer. So either somebody's made a subtle error, totally possible, right? And they both worked really, really hard to reduce these uncertainties. Often in this scenario, you get two experiments, they get different measurements, but they both have large uncertainties and they overlap. And then they both work really, really hard to refine their experiments. And usually, as the uncertainties shrink, the results converge into one answer. You're like, okay, cool. The universe is coherent. But what's happening here is that the uncertainties are shrinking, but the answers are not getting closer together. So they're getting more and more confident in their discrepancy, which means, hey, maybe there's some new interesting physics.

• 19:57Daniel Whiteson?

  Maybe the neutron, like the boring vanilla particle most people aren't excited about, is actually the portal to discovering the nature of the universe.

• 20:06Kelly Weinersmith?

  You all are pros at silver linings.

• 20:10Daniel Whiteson?

  Well, this is a really fun idea that maybe neutrons don't just decay to protons. Maybe sometimes neutrons decay into something else like dark matter. And so in the neutron beam, what's happening is these neutrons are just disappearing into dark matter, and those guys are not measuring it. So maybe the bathtub guys are right because they're actually measuring the neutrons. Whereas the guys who are assuming they turn into protons, they're the ones getting the wrong answer because it's not always going to protons. Sometimes it's going to dark matter.

• 20:38Kelly Weinersmith?

  And we can't measure dark matter, right?

• 20:40Daniel Whiteson?

  We do not have ways to measure dark matter, certainly not in these beams. And so this is really interesting and really important because it could be an indication of something that's happening. And it's also important because it helps us understand the early universe. You know, the very early universe, we had like quarks and gluons flying around and things cooled down into hydrogen and briefly also forming some helium. And that ratio of hydrogen and helium is super important because it tells us something about the Density of quarks at that time and what the early universe was really like. And we need neutrons in order to form helium. Like you can't form helium without neutrons. You can't just squeeze protons together. You have to have those neutrons to facilitate. But if the neutrons decay a little bit faster, then they aren't around as long to make helium.

• 21:25Daniel Whiteson?

  If neutrons decay slower, there are more of them to stick around and make helium. More helium means smaller, longer lasting stars. So it has this cascading effect on the whole history of the universe. Super fascinating. Anyway, neutrons really amazing. Thank you very much, Scott, for asking about this. And I hope that we've answered all of your questions about neutrons and inspired new ones. Let's hear what Scott has to say about our story of neutrons.

• 21:53Speaker 03

  Hi, Daniel and Kelly. Thank you for the thoughtful answer. It seems like the neutron has a PR problem and I'm just not okay with that state of affairs. Neutrons do some very cool and rather important things and the world really needs to know. As a follow up question, if a free neutron decays in a matter of minutes, does that imply that the study of neutron guts is practically more difficult than the study of proton guts? Thanks again for everything you guys do.

• 22:22Daniel Whiteson?

  Great question. Well, we can study neutrons because there are lots of them. But seeing them fall apart is actually useful because it gives us something to measure, to predict, to calculate. Protons, on the other hand, just sit there. So we have to do some work to smash them or poke them to learn anything. So neutrons are actually being helpful.

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• 26:17Kelly Weinersmith?

  All right, so I gotta tell you, I'm on the edge of my seat trying to figure out what ties together all of the three questions that we got today. It's still not clear to me, other than the fact that like bananas are made of protons and neutrons. Is that it? Was it that simple?

• 26:31Daniel Whiteson?

  No, that's not it. It's more than that.

• 26:33Kelly Weinersmith?

  It's gotta be more than that. Okay, so our next question is about bananas. Matt from Discord had this question.

• 26:40Speaker 05

  Hi, Daniel and Kelly. This is Matt from Indiana. I was walking through the grocery store and noticed there are all sorts of varieties of peppers. Red, green, tiny, big, yellow, orange, tons of apple varieties. Red, delicious, Granny Smith. And then I got to the bananas, just bananas, plain bananas, no matter where I go. And then I found out that most bananas we eat are banana clones. So why banana clones and not from seeds is what I'm curious of. Thanks in advance.

• 27:11Kelly Weinersmith?

  And thanks for giving me an excuse to say bananas way too many times. Oh, man. So I was excited to have an opportunity to read more about bananas. So let's start with banana reproduction. Bananas can reproduce in two different ways. They reproduce sexually by making seeds and they reproduce asexually by producing suckers.

• 27:33Daniel Whiteson?

  Hold on, wait, I have a question already.

• 27:35Kelly Weinersmith?

  Okay, great.

• 27:35Daniel Whiteson?

  First of all, bananas reproduce or banana trees reproduce, right? Because the bananas themselves are just part of the banana tree, right?

• 27:42Kelly Weinersmith?

  Yeah, yeah, yes, you're right. You're right. I was being lazy with my words. Although I'm going to call you on it because bananas aren't really trees. I think technically they're herbs.

• 27:51Daniel Whiteson?

  Really?

• 27:52Kelly Weinersmith?

  Do you remember in one of our other episodes, we were talking about the anatomy of the tree and how it forms rings? Bananas are just taxonomically distantly related. They don't form that way. They just kind of have like a stalk that's really trunk and tree like in the middle. But they're not like typical trees.

• 28:09Daniel Whiteson?

  Wow. All right. So banana trees are not trees. I've already learned something. And what part of the plant is the banana? Is it fruit the way an apple is? Is it something else weird? I remember strawberries or something totally different. Which part of the plant are we actually snacking on?

• 28:23Kelly Weinersmith?

  It is the fruit.

• 28:24Daniel Whiteson?

  Okay.

• 28:24Kelly Weinersmith?

  Yeah, yeah. What do you mean by strawberries aren't really the fruit? I'm confused.

• 28:28Daniel Whiteson?

  Didn't we do an episode where like strawberries are actually the seed or something? I don't remember. I remember learning something surprising about strawberries.

• 28:34Kelly Weinersmith?

  Strawberry seeds are on the outside, which is atypical, but was that the whole fact?

• 28:39Daniel Whiteson?

  Anymore. Biology doesn't stay in my head as long as physics does.

• 28:42Kelly Weinersmith?

  Oh, no.

• 28:43Daniel Whiteson?

  Busted.

• 28:44Kelly Weinersmith?

  Let's get away from this.

• 28:45Daniel Whiteson?

  So back to bananas. Bananas are the fruit, but they're not technically growing on trees. Because I thought fruit had to grow on trees.

• 28:51Kelly Weinersmith?

  No, I mean like strawberries aren't growing on trees.

• 28:53Daniel Whiteson?

  Hmm. All right. Cool.

• 28:55Kelly Weinersmith?

  Although I guess maybe we're not quite sure if strawberries are fruits. We're all confused today.

• 28:59Daniel Whiteson?

  I'm not sure. It doesn't mean that people aren't sure.

• 29:01Kelly Weinersmith?

  Okay, got it, got it.

• 29:02Daniel Whiteson?

  I'm part of an expert. All right. So bananas can reproduce sexually or asexually, you were telling us.

• 29:07Kelly Weinersmith?

  Yes. And so what happens with the asexual reproduction is that the giant stalk that looks like a trunk at the bottom underground, in addition to its roots, it's producing what are called suckers. And these suckers come out from the mother plant and pop up along. The sides and they are essentially just clones of the mom and they'll stay connected for a while, but you can cut them off, move them somewhere else. And now you've got a new banana plant.

• 29:33Daniel Whiteson?

  And why do biologists call them suckers? I mean, that makes me think of the things on an octopus's tentacle. Are these like an octopus tentacles sticking out through the ground? Or what's going on here? Do they suck in some way?

• 29:43Kelly Weinersmith?

  I don't know the history, but it's just a much more fun name than any of you guys would have come up with. I'm kidding. Gluons is a great name.

• 29:51Daniel Whiteson?

  I wish we had called some particle the suckers. That would have been really fun.

• 29:53Kelly Weinersmith?

  You might discover a new particle and I think that's what you should name it.

• 29:57Daniel Whiteson?

  In the sucker's beam.

• 29:58Kelly Weinersmith?

  That's right.

• 29:59Daniel Whiteson?

  So they can basically clone themselves, make little mini versions, or they can actually get it on with their neighbors.

• 30:05Kelly Weinersmith?

  That's right. And there's something like a thousand species of plants that could be called banana plants.

• 30:11Daniel Whiteson?

  Oh.

• 30:11Kelly Weinersmith?

  So there's a lot of diversity, but at some point in the past, so like bananas don't fossilize. So it's hard to know exactly when humans started eating bananas, but way before written records were a thing for our species. What we think happened was that a banana plant had a mutation and it didn't produce seeds. And you would know if your banana had seeds in it because the seeds produced by lots of banana plants are big and hard and it would be very unpleasant to eat a banana with seeds in it. And so bananas don't have seeds and some human must have found this tree and they were like, oh, this is solid. There's nothing that cracks my teeth in this plant. And so they took the suckers and that got propagated.

• 30:53Daniel Whiteson?

  But this is like prehistory because we don't have records of it. We don't know when this happened?

• 30:57Kelly Weinersmith?

  That's right. Yeah.

• 30:58Daniel Whiteson?

  So could it also have been the product of like human breeding? We found like a plant with smaller seeds and another one and then crossbred them and pushed them in that direction? Or do you think it's more likely just like one random mutation?

• 31:09Kelly Weinersmith?

  Artificial selection could have helped it along. I believe our understanding is that this happened before humans really had enough of an understanding to engage in artificial selection on purpose.

• 31:23Daniel Whiteson?

  Wow.

• 31:23Kelly Weinersmith?

  But it certainly could have been the case that Joe had a plant that had two seeds in it and Sally had a plant that only had one and everybody wanted the suckers. From Sally's plant, because that's way better. And over time, that process could have played out. But I don't think it was purposeful initially.

• 31:38Daniel Whiteson?

  And so that was the last sexual reproduction of these bananas that we're eating. And every reproduction of banana trees since that moment has been asexual.

• 31:47Kelly Weinersmith?

  So my understanding is that there have been strains that have arisen through this process. So it didn't necessarily happen just once. It could have happened in like five different banana trees in different areas. And now you've got these different clonal lineages. But there's still all of those wild banana species out there that are still producing seeds.

• 32:03Daniel Whiteson?

  I see. Okay.

• 32:04Kelly Weinersmith?

  So around the 1900s, there was a strain of bananas called the Gros Michel, which means Big Mike.

• 32:12Daniel Whiteson?

  It sounds so much fancier in French.

• 32:14Kelly Weinersmith?

  It does. But the Big Mike was everywhere and I'm going to bum everybody out, which is exactly what everybody expects from me. Apparently, the Gros Michel bananas tasted better than the bananas we have now.

• 32:25Daniel Whiteson?

  Wow.

• 32:26Kelly Weinersmith?

  But they were all clones. And so these were being grown all over the world. Bananas were getting huge. They're being shipped all over the world and a fungal infection broke out. And because all of the Gros Michelles were clones, they were all susceptible. And it decimated the bananas around the world.

• 32:44Daniel Whiteson?

  Sacre bleu.

• 32:45Kelly Weinersmith?

  Sacre bleu. We're sorry, French speakers.

• 32:49Daniel Whiteson?

  Wait, do you know what the Gros Michel tasted like? Do we have like written records or living people who have eaten them? Who can tell us about this banana that none of us will ever eat?

• 32:58Kelly Weinersmith?

  There probably are some people still alive who have eaten it. I think it was just a sweeter tasting banana than what we have now. I know.

• 33:06Daniel Whiteson?

  The lost bananas.

• 33:07Kelly Weinersmith?

  I know.

• 33:07Daniel Whiteson?

  Oh, my gosh.

• 33:08Kelly Weinersmith?

  It is sad. It is sad.

• 33:10Daniel Whiteson?

  Is there somebody out there who's like going to de-extinctify the Gros Michel? That sounds like a billion dollar idea right there.

• 33:16Kelly Weinersmith?

  Yeah, so there might be someone who's still maintaining the suckers from the Gros Michel in some lab somewhere. But it remains susceptible to Panama disease, which is what we call this fungal disease that wiped out the bananas. So somebody maybe could bring it back. But when the Gros Michel declined, the Cavendish arose. And the Cavendish must have just been a slightly different strain that happened to be resistant to the dominant. Fungal strain at the time. And so Cavendish, if you live in North America, this is the banana that you find on your grocery shelf. So if you go to Harris Teeter, or you go to Target, or you go to Kroger, or you go to Trader Joe's or Whole Foods, those are all the same banana genotypes. They're clones everywhere you go.

• 34:00Daniel Whiteson?

  They all have the same DNA, you're saying?

• 34:02Kelly Weinersmith?

  They all have the same code in their DNA. There could be a couple of mutations, but they are very similar.

• 34:07Daniel Whiteson?

  Wow, amazing.

• 34:08Kelly Weinersmith?

  In countries like Africa and India, they have a greater appreciation for other banana varieties. So there are other parts of the world where you can get other kinds of bananas, but in the US, we get this one.

• 34:18Daniel Whiteson?

  I've traveled in Mexico and the grocery stores there, they have lots of different kinds of bananas. They have like little dark red bananas that taste a little bit like strawberries, and you know, big fat bananas and all sorts of stuff. It's a lot of fun.

• 34:29Kelly Weinersmith?

  Yeah, and plantains are fairly popular in the US. And I think that's another strain where there were no seeds that were made, and then that got propagated by suckers. But in the 1990s, bad news.

• 34:41Daniel Whiteson?

  Oh, no.

• 34:42Kelly Weinersmith?

  The Cavendish gets affected by Panama disease. So this fungal disease has continued to evolve while the Cavendish is staying still in this evolutionary arms race, because it's just a clone that we propagate over and over and over again. And there's now a strain of Panama disease that is going after the Cavendish bananas.

• 35:02Daniel Whiteson?

  Why do they hate us so much?

• 35:03Kelly Weinersmith?

  I know, I know. Fungus is the worst.

• 35:07Daniel Whiteson?

  Except when it's helping us make beer and bread and all sorts of other yummy things.

• 35:11Kelly Weinersmith?

  You know, I guess whenever you say a blanket statement, you're almost always gonna be wrong.

• 35:14Daniel Whiteson?

  Some of them are really fun guys, actually.

• 35:16Kelly Weinersmith?

  Oh, dad jokes, dad poetry.

• 35:21Kelly Weinersmith?

  Okay, so now we've got Panama disease and it is spreading. And so there are some people who will be concerned, what happens if the Cavendish declines? Do we have something waiting to replace it? And the answer is no.

• 35:35Daniel Whiteson?

  No.

• 35:36Kelly Weinersmith?

  No.

• 35:36Daniel Whiteson?

  What?

• 35:37Kelly Weinersmith?

  No.

• 35:37Daniel Whiteson?

  What are these people doing? Get on it, food scientists?

• 35:40Kelly Weinersmith?

  There is a lot of money in bananas. So there's a lot of people working on it. The first thing that they're doing to try to slow the decline is biocontrol efforts. So if you go to a major banana plantation and you want to go amongst the trees, you have to suit up in sterilized clothes. You have to put on boots and then walk through sterilizing solution. And you have to do that every time you walk from like one plot of bananas to another, because the way the fungus transmits is in the soil. So if you get like dirt in your boots and then you walk in another area, you can transmit that.

• 36:13Daniel Whiteson?

  Wow.

• 36:14Kelly Weinersmith?

  So it's a pain in the rear end. And like every truck that comes in and out has to get sprayed. But if they do find a tree that's infected, they have to dump fungicides into the soil, kill everything in that area, cover it with urea, which I think just also changes soil chemistry, making it more likely to kill the fungus, cover it with a tarp so that birds don't walk on it and then bring the fungus somewhere else. The next zone of plants also get like fungicides and herbicides injected into the soil. And then the zone after that, you have to check, like every month, you have to do like a survey to make sure none of them have it. And so it's intense.

• 36:50Daniel Whiteson?

  Biology is just so hard to control. It's always wriggling and squirming out of our control.

• 36:55Kelly Weinersmith?

  Yes. Well, man, an invasive species. I feel like it's such an interesting conversation about when do you just give up? Like, it's not worth trying to get starlings out of the US anymore. They're not going anywhere. They're here. Anyway.

• 37:06Daniel Whiteson?

  Well, what about bananas? Is there anything else we can do? Like, can't we somehow protect our bananas or cross them with other wild species or something?

• 37:14Kelly Weinersmith?

  Yeah, I can hear the panic building in your voice. Don't worry. We have a couple options.

• 37:18Daniel Whiteson?

  I like banana bread, okay?

• 37:19Kelly Weinersmith?

  I know, me too, me too. Zach makes a good banana bread. I don't get in the kitchen, but he does a great job. So genetic engineering is one solution. And they have, in fact, added genes from other plants, I think tomato, to make the Cavendish resistant to Panama disease. And this works. It is resistant. But in the European Union, I believe you're not allowed to sell genetically modified plants. And in the United States, there's a lot of people who feel very squeamish about genetically modified plants. And so the industry has decided that this can't be the solution. It just would not be financially viable.

• 37:51Daniel Whiteson?

  Wow, so he could save the bananas, but still it's not good enough.

• 37:55Kelly Weinersmith?

  Not good enough. And so the last thing that they're trying are breeding experiments. So apparently something like one in 10,000 bananas will produce a seed. Sometimes it like still slips through. So you can search bananas for that seed and then cross the cavendish with other species of wild bananas. And so there are some efforts to cross breed. But the problem is like the cavendish, it's actually an absolute marvel of a fruit. You know, it comes in its own packaging that ripens over the course of a week while it is in transit to you. So it arrives to you mostly unbruised and now perfectly ready to eat. And the various crosses that they've done have produced bananas that are like, you know, maybe they're yellow.

• 38:39Kelly Weinersmith?

  Maybe they still have a good, you know, outer coating. But so far they haven't been able to find anything that meets all of their criteria and is delicious. I was reading about one banana that looks like a cavendish and tastes good. But it's described as an acid banana, which doesn't sound delicious. But it just doesn't taste like the cavendish. And so right now they haven't been able to find anything to replace the cavendish. And what some people would say is a more sort of natural method. So that's where we are. Are we going to have a banana in one to two decades? We'll have to wait and see.

• 39:12Daniel Whiteson?

  Oh, my gosh. Our children or our grandchildren might never know the taste of bananas. The way we don't know the taste of the grow me shell.

• 39:20Kelly Weinersmith?

  I know, it could be tragic. I mean, think of how many babies had bananas as their very first food or something like. It could be that my kids' first foods were smushed up bananas. My memory is a sieve, so I don't know exactly what I fed them the first time, but it could have been a banana.

• 39:34Daniel Whiteson?

  And you know, there's something else fascinating about bananas, which is that they are radioactive.

• 39:40Kelly Weinersmith?

  Is that going to be the connection?

• 39:41Daniel Whiteson?

  Don't give it away, Kelly. But yes, inside bananas, there's naturally occurring potassium 40, which is unstable. And the neutrons inside potassium 40 decay. And so if you are hanging around a banana, it will emit high energy electrons and anti neutrinos. Which is technically radiation.

• 40:00Kelly Weinersmith?

  Oh, would we all be better off without bananas in our life?

• 40:04Daniel Whiteson?

  I don't know, bananas contribute to the natural radiation background, which I'm sure affects the mutation rate. So it's made all of us who we are.

• 40:11Kelly Weinersmith?

  Oh, wow. Okay. On that deep dad poetry note, let's find out if Matt found this answer satisfactory. And we'd also like to take this moment to thank Matt for being an amazing moderator of our Discord channel. And if you want to join us on Discord, go to danielandkelly.org, not dot com, although dot com appears to be a dead link now because the other Daniel and Kelly got married and their website is down.

• 40:35Daniel Whiteson?

  Which means either the wedding went wonderfully and they don't care about it anymore, or maybe something didn't go so well.

• 40:40Kelly Weinersmith?

  Oh, man, I'm hoping for the former.

• 40:42Daniel Whiteson?

  Yes. Good luck, Daniel and Kelly.

• 40:44Kelly Weinersmith?

  Yes.

• 40:44Daniel Whiteson?

  But please do join us on the Discord where lots of people are asking questions and having conversations about science and pizza and all sorts of crazy stuff. Go to danielandkelly.org to find the link to join the Discord.

• 40:56Kelly Weinersmith?

  And let's hear what Matt had to say. That answer was beautiful. Thank you so much. Now I know more about banana suckers than I've ever wanted to know. And also thanks for giving me a shout out on the Discord for being administrator there. And we really do hope other people will join, just like Daniel

• 41:11Speaker 04

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• 44:52Daniel Whiteson?

  All right, we're back and we are answering questions from listeners. There's a special secret theme of today's podcast. It's going to tie all of these questions together. Let's see how long it takes Kelly to figure it out.

• 45:03Kelly Weinersmith?

  How many lifetimes?

• 45:06Daniel Whiteson?

  The next question is from Steve, who has a question about the biggest gassiest planet in the solar system.

• 45:12Kelly Weinersmith?

  That isn't Uranus. Sorry, I had to.

• 45:18Speaker 05

  Hi, Daniel and Kelly. This is Steve from B.C., Canada. I have a controversial take here. Could it be said that there is no such thing as a gas giant? Because these planets have so much pressure that gas becomes liquefied. So aren't they really liquid planets? Maybe liquid giants? Sure, they are composed of liquid elements that are gaseous to earthlings living in earthly pressures. But they are not Earth and they don't have earthly pressures.

• 45:50Speaker 06

  So we should be calling them liquid giants, don't you think? I think it's about high time that we do a deep dive into the inner workings of gas planets. What really are they?

• 46:02Daniel Whiteson?

  All right. So Steve is asking a question about the science of Jupiter, but also about the name of the category that Jupiter finds itself in, gas giants. Are they really gassy? Should we be calling them liquid giants? These are good questions, Steve.

• 46:15Kelly Weinersmith?

  These are great questions. Yeah. And you gotta tell Jupiter, lay off the beans.

• 46:20Daniel Whiteson?

  No, no, we're pro beans, even if it makes you gassy. Katrina would tell me that beans makes everything better.

• 46:26Kelly Weinersmith?

  Nobody knows better than Katrina.

• 46:29Daniel Whiteson?

  She certainly does. She certainly does. All right. So let's dig into it. What in the end is Jupiter made out of? Well, Jupiter, like Earth and the sun, formed from this big blob of stuff that the whole solar system was made out of. And you know, the solar system is mostly just the sun. Like the sun has 99 point something percent of all the mass in the solar system. Basically, you have a much larger cloud of stuff that our solar system and other solar systems formed from. But there was in there some seed, some gravitational over density that pulled stuff together to form our solar system. And mostly that just collapsed into the center. And most of it was hydrogen, because that's what the universe started out at. As in 14 billion years later, we're still mostly hydrogen. And so the sun is mostly hydrogen.

• 47:12Daniel Whiteson?

  But near the sun, there were also other little areas of over density that managed to pull themselves together and hold themselves together and resist the sun's attraction. And that's how the planets formed. So you get small rocky planets like Earth in the inner solar system, because the sun then blew away their atmospheres. But far enough out away from the sun, the sun's radiation didn't blast away all the helium and hydrogen. And there was ice out there. Things were cold enough to form ice crystals. So you had a little bit of an advantage to make bigger planets that could grab a little bit more mass. So Jupiter is just a scoop of the original protosolar system that everything else is made out of.

• 47:49Kelly Weinersmith?

  Oh, so it's a better representation of the protosolar system than Earth?

• 47:53Daniel Whiteson?

  Yeah, absolutely. Earth once had an atmosphere of hydrogen the way that the sun does and the way Jupiter does, but it was blown away by the early sun. And so the Earth is not a great representation of what the solar system is. And actually, we're going to do an episode pretty soon about how we know what the universe is made out of. And it was a big shocker when we discovered that most of the universe is not made of the same stuff as the Earth. The Earth is an unusual helping of solar system or universe material.

• 48:18Kelly Weinersmith?

  Thankfully for us.

• 48:19Daniel Whiteson?

  Yes, exactly. Thanks for the applause. That's why we have bananas. No, that's not the secret theme. So Jupiter is mostly hydrogen, right? By mass, the outside is like 76% hydrogen, and then 24% helium, and then just like trace tiny other stuff, like a little bit of carbon, a little bit of oxygen, a little bit of sulfur, a little bit of neon. But the atmosphere, which is just really an artificial designation of like a certain layer within Jupiter, is mostly hydrogen and helium.

• 48:47Kelly Weinersmith?

  What would be the arbitrary divider for Jupiter? I do think of Jupiter as being just gas all the way through. And maybe that's just because it's called a gas giant. So what is the dividing line or dividing criteria for the atmosphere versus the interior?

• 49:03Daniel Whiteson?

  Yeah, so it's a little bit arbitrary, but basically you have layers of stuff that get denser and denser as you go in. So you start out the very outer layers of Jupiter are cloud layers. And so these are like ammonia crystals, there's really high winds, but it's mostly gaseous hydrogen with these clouds of ammonia crystals. And that's what you see when you look at Jupiter, you know, like the rings and the red spot and all this stuff. These are like weather patterns in those clouds in the very, very top layer of Jupiter's atmosphere. But then, once you penetrate through those layers of clouds, like 50 kilometers of clouds or so, below that, there's liquid hydrogen, right? And so hydrogen is an atom, but it also forms H2, which is a molecule. And then it has

• 49:48Daniel Whiteson?

  various phases, and it depends on the temperature and depends on the pressure. And so you start out with gaseous hydrogen, and then you squeeze it down, and you get liquid hydrogen. And so this stuff flows, right? It's just denser. And so you might say, all right, we're not really in the atmosphere anymore, because now we have a liquid. And you know, here on Earth, we consider the atmosphere the gaseous part, and then the surface is where you have like solid rock and also liquid. But it's not quite so simple on Jupiter, because it's not as clear and crisp. Like here on Earth, you know, you have liquid, and above it is gas. And like, if you're swimming in the ocean, you can very clearly tell the crisp difference. But on Jupiter, they don't really have the same distinct transition between liquid and gas.

• 50:29Daniel Whiteson?

  And so you have this like gradual transition between gaseous hydrogen and liquid hydrogen. What's really going on here is that molecular hydrogen, if you look at its phase diagram, there are some pressures and temperatures where it's gas and some pressures and temperatures where it's liquid. But there's this critical point, this temperature and pressure above which it's not really gas and not really liquid. And this transition is sort of therefore gradual. There's this sort of super critical fluid. It's not really technically a liquid, it's not really technically a gas, it has some similarity to both. And so the reason you can't just say like, oh, this is the surface of Jupiter is that as you descend, it just sort of gets denser and denser till eventually it feels like liquid.

• 51:11Daniel Whiteson?

  And if you rose back up, it would get less and less dense and then it would just sort of feel like gas. But it's a gradual transition rather than an abrupt one, the way it is here on Earth.

• 51:20Kelly Weinersmith?

  I see we have yet again accidentally forayed into chemistry. But I understand it better now.

• 51:26Daniel Whiteson?

  And as you descend, the weather gets really, really weird. So you get this like helium neon rain.

• 51:32Kelly Weinersmith?

  What?

• 51:33Daniel Whiteson?

  Yeah, I know, it's really crazy and not something I think you should dance and sing in, for example. But these are sort of rain like droplets. And what's happening is that you have helium and neon in the upper atmosphere, but they come together and form these drops, which then sink and depleting the abundance of these elements in the upper atmosphere. And they fall down to lower levels of the atmosphere. And this is all very speculative. You know, there are people who think, for example, like on Saturn, there might be conditions that cause diamonds to rain. You know, like formation of diamonds in the atmosphere because the intense pressure, which then fall below. But a lot of this is speculative. This is like people running models and thinking, maybe this is what happens. And it's super cool, but you know, the big picture story here is that we really don't understand this stuff. A lot of this is just speculation.

• 52:18Kelly Weinersmith?

  Which is why we need more money to go out there and find out.

• 52:21Daniel Whiteson?

  Definitely do. And then things get even weirder. As you squeeze it down, as you go down further towards the center of Jupiter, you're getting higher temperature and higher pressure. Then you reach this region where the hydrogen is metallic, right? And metallic is a really weird term to apply to hydrogen because in astronomy, usually they say, well, you have helium and you have hydrogen. Everything else, they call a metal. All right. So if you talk about the metallicity of stars, it means how much of the star is not hydrogen? How much of it is not helium? Everything else, they call a metal. Chemists have a different meaning for what is a metal, right? They're thinking about things where the electrons are flowing because the atoms are sort of linked together. The electrons are not attached to individual atoms. And that's what we're talking about here.

• 53:04Daniel Whiteson?

  This is like the chemical version of a metal.

• 53:07Kelly Weinersmith?

  Does it mean that the atoms are flowing? Are we using the chemistry definition now?

• 53:10Daniel Whiteson?

  Yeah, we're using the chemistry definition because what happens is you take those H2 molecules, you squeeze them together and the hydrogen forms something like a lattice. All right. Instead of having individual H2 molecules, which have some interaction, you know, because of the polarity of them. Now you're squeezing them together. So the electrons can just jump from one hydrogen to another hydrogen to another one. It's like a big crystal. It's not quite as tight, but it conducts electricity, right? Normally hydrogen does not conduct any electricity. But you squeeze it together, you make it dense enough, it will conduct. And so it has this like bulk lattice phase with de-localized electrons in it. And this is something people have been thinking for decades and decades.

• 53:51Daniel Whiteson?

  And only the last few years have they been able to convincingly make this stuff in the lab by recreating these conditions and seeing it actually conduct electricity.

• 54:00Kelly Weinersmith?

  Wow.

• 54:01Daniel Whiteson?

  So this is huge chunk of Jupiter, which is hydrogen squeezed so tight that we think it's basically one enormous conductor.

• 54:09Kelly Weinersmith?

  So when you touch metallic hydrogen, is it hard? Like the metals that I am thinking of?

• 54:16Kelly Weinersmith?

  Or are we still in a sort of like gassy, liquidy kind of phase?

• 54:19Daniel Whiteson?

  Yeah, great question. Not something we understand super well, but I don't recommend you lick it if somebody has some metallic hydrogen. It's hard to imagine what it'd be like to touch it because you can't have it around unless it's under very, very high pressure. So it's not like somebody could hand you a chunk of metallic hydrogen that you could like even consider licking.

• 54:35Kelly Weinersmith?

  Okay.

• 54:36Daniel Whiteson?

  It's just gonna be like super duper dense material.

• 54:38Kelly Weinersmith?

  Got it. Okay. I don't want to die for this podcast.

• 54:40Daniel Whiteson?

  Probably not tasty. I'd recommend a banana for a snack instead of metallic hydrogen.

• 54:45Kelly Weinersmith?

  Wait, hold on. What is the connection then? Is the connection that there's a part of Jupiter that's solid like a banana? And the equipment we use to study neutrons is solid too? Daniel, I just don't know.

• 54:56Daniel Whiteson?

  Well, Jupiter is active, right? The same way the sun is, it's a big hot thing and so it radiates. There's no fusion going on inside Jupiter, but you know, the pressure and the temperature are very high. And so there is a lot of radiation being emitted. If you wanted to, for example, establish a base on one of the moons of Jupiter, you'd really have to worry about the Jupiter wind, the Jovian winds, very high energy particles shooting at you. So just like a banana and just like a neutron, you have to worry about radiation if you're gonna live near any of these things.

• 55:26Kelly Weinersmith?

  Radiation is the theme.

• 55:30Daniel Whiteson?

  It's a particle, of course. I'm not trying to be tricky about it.

• 55:34Kelly Weinersmith?

  Well, I got it before the end of the episode almost. So bravo, Kelly.

• 55:38Daniel Whiteson?

  Congratulations. You get a banana. If I had a grow Michelle, I would share it with you.

• 55:41Kelly Weinersmith?

  Oh, thank you.

• 55:42Daniel Whiteson?

  So then we can dig down even deeper into Jupiter and eventually you get the stuff that's not hydrogen. So we think there's a really thick atmosphere. Metallic hydrogen is up to like maybe 80% of the radius. If you go down to like 30 to 50% of the radius of Jupiter, there is stuff down there that's solid. It's like made of rock, the same kind of stuff that the earth is made out of. And it's not small. It's like 30 to 50% of the radius of Jupiter. It's a really big chunk of ice and rock. But you know, it's buried under an incredibly thick layer of hydrogen. And so if you're really hardcore about, you could say, well, that's the surface because everything else is a gas. It's hydrogen, but you know, it's not in a gas phase. It's in a metallic phase or it's in a super critical fluid phase.

• 56:26Daniel Whiteson?

  And so you could, if you dove really deep into Jupiter, stand on a rocky quote unquote surface, but I don't think you could still call Jupiter a rocky planet.

• 56:35Kelly Weinersmith?

  All right. Yep. I'm giving it to the astronomers. I think gas giant is a reasonable name and also it gives many school kids lots of chuckles. And so I think it's great.

• 56:44Daniel Whiteson?

  Yeah, but it is confusing, right? Because we call it a gas giant because it's mostly made of hydrogen, but hydrogen is not always in a gaseous state, especially in Jupiter. Most of the gas on Jupiter is metallic. So you could also call it a metallic giant and be like, kind of correct.

• 56:58Kelly Weinersmith?

  That does sound cooler.

• 57:00Daniel Whiteson?

  It does sound more metal, right?

• 57:02Kelly Weinersmith?

  That's right. That's right.

• 57:03Daniel Whiteson?

  All right. So I think we've concluded that astronomy names are very confusing and maybe there's no way to do it right. But it's fun to dig into anyway. And so Steve from B C, let us know if we answered your question about Jupiter.

• 57:16Speaker 05

  Thanks, Daniel and Kelly for answering my question. That was really insightful to know that Jupiter could be really a metal giant. But it makes me think now about how we've named Earth. You know, Earth has a lot of gas and we depend on that gas. And you know, how much different is the amount of gas and rock ratio than Jupiter? I mean, would it be correct to say that Earth is a gas midget? Thanks again for answering my question. You're still my favorite podcast. Keep the great answers coming and thank you for being such great science communicators.

• 57:50Kelly Weinersmith?

  Well, thank you for all of the wonderful questions we got today, and we hope to hear from you. Send us your questions at questions at danielandkelly.org. We answer every question and some of the questions even end up on the show.

• 58:02Daniel Whiteson?

  We do love to hear from you and we love to hear that you are curious, that you share our passion to understand the universe, how it works from the bananas all the way out to the galaxies. So join us on the Discord, write to us at questions at danielandkelly.org. Let us know you're out there.

• 58:25Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

• 58:30Daniel Whiteson?

  We really would. We want to know what questions you have about this extraordinary universe.

• 58:36Kelly Weinersmith?

  We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you.

• 58:43Daniel Whiteson?

  We really mean it. We answer every message. Email us at questions at danielandkelly.org.

• 58:49Kelly Weinersmith?

  Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms, you can find us at D and K Universe.

• 58:58Daniel Whiteson?

  Don't be shy. Write to us.

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