Dark Matter and Cosmic Evolution

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Neil degrras Tyson here, you're a personal astrophysicist. This is going to be cosmic queries on The formation of planets in the universe. I got with me, my coost, Nagin Fasade. Oh my God, hello. Welcome back. I'm so excited. I I've like peeped at some of these questions and they are. Well, yeah, 'cause they were very delicious., qu delicious. I love that Very good. And just a reminder, you still have your Fake the Nation podcast. That's right. Every week. Every week. And it's a delight anytime I hear you on wait, wait, don't tell me. Thank you. That is the NPR, right? Yeah. NPR Mainstay. An NPR Main Day, I've got a lot of tote bags to prove it. We have a good time. All right, let me introduce you to my guest today. He's a longtime friend and colleague Mordecaai, Mark Meclo, Mordecaai. Well, hello Nil. It's weird to. It's only been thirty seven years that we've known each other. Yeah. Yeah so I mean, we came up together, you know, through graduate school, not at the same graduate school, but we're about the same generation U it was he's one of the earliest hires into our brand new department of astrophysics. Number one. Oh you were the number one h. I am number one.' another way to say that you found? Is that a way of saying that he's better than you? No is I understand founded the department. Oh gosh I was his number one. Okay you're just better than everyone else here. we was still better. That's what you're looking for. ago. N numberber one m he was hired first Not that he's the number one guy. We're all number one here. No. And what was a delight? in your research profile is that you just need a powerful computer and the universe succumbs to you. Well, it's a good sandbox. Tell me what you do Be most people's stereotype of the astronomer, astrophysicists, were at the telescope Or maybe we're we're crunching numbers on not numbers, but we're on a theorists noteepad. and you are in the middle of that. some simulator. So I do I run computer programs that are you wring Well, that I and my colleagues right? Yes. that that describe how partarts of the universe behave Using mathematical equations derived by theorists but using the computer to derive consequences that would be absolutely impossible to do with pencil and paper mathematics So when things get hairy, we pull out a computer. Do you ever like use your powers of simulation for like you know, a vision of a grilled cheese sandwich or is it mostly just like space? Well I would say that I may not do the grilled cheese sandwiches, but there is a simulator somewhere who does.. And they probably work for craft or something. And they should be your next guest. There you go. So Mortica, I remember when we were coming up, there was a catalogue of galaxies your galaxies it was called the Atlas of peculiar galaxies. And Ap yeah, Halt and ARP. And we all scratched our heads wondering How would nature make Ojects that look like this. Like bug splats. Yeah. the galaxies just what? What? and I think in our lifetime bringing computers to bear arms at probleblem. We would fully understand How you get a disturbed looking galaxy? So that's actually an interesting story because the very first simimulation that was done of colliding galaxies that made a bug splat and reproduce these peculiar observations was done in the nineteen forties using lamps and photo detectors. And as an analog computer because the lamps simulated gravity because light It drops off an intensity just like gravity does And that actually revealed the basic picture that you get these splats, these tidal tails, we call them thenen we came along and refined that insight with the actual heareers. Yes. But the first one What's those phot detectors. Interesting That wouldn't be Homberurg, wasn' it? I think it was. Hburg. Yeah.. I remember that. Yeah. ye. So you've written about that. But I was just a triumph of the simulation modeling universe where So there's a famous astronomer in the day. he would say Alexis That's wrecked in an accident is not a different kind of Lxus It's just are lex. And so a wrecked galaxy could have been a perfectly nice galaxy But then it collided with another galaxy and with your computer, you can check what it looks like at every step That's correct. And then then look at the universe and find find those steps. All of those stepses being taken by colliding galaxies. And that's how we learned that Bug splats turn into beautiful elliptical galaxies, smooth, uniform, homogeneous because they get completely their disk galaxies that get completely Blenderized And that's the origin of the elliptical galaxies Furthermore, Every galaxy in the universe has collided with other galaxies. That's how galaxies are made. Wait, so is it that like when a when two galaxies collide? Is it sort of like say it more romantic Tw galaxies. When two galaxies collapse. Its come together. But when that happens it it like They're at a stop sign and neither of them is willing to go so then they just smash into each other. Well, it's like this. Galaxies are made of stars and gas and dark matter. And stars are very widely separated from each other So the stars just go by each other. Maybe they tug each other a little gravitationally, but basically They're not going run into each other. If there were four Bumble bees in the continental United States. lying randomly There's a greater chance that two of them will accidentally bump into each other than two stars will collide you know galaxies That's about right. I'm hearing there's a lot of space.. That's what we're doing. Okay, God, God. However Gas is space filling. And so the gas runs into each other and lights up, huge shockwaves, dust clouds running into each other, new stars forming. all that goes on during the collision. I got a good analogy for colliding gas pl Two hot marshmallows You. They're stuck No Have you done this look at me like what is he talking about? I mean I am too. Have you Rasted marshmallows and thenampire throw them at each other like I have. what trips you went on. We ate the marshmallows. He's looking at us like we're the weird ones. I don so, but I like this. so they don't they stick together and then that's it they become one marsmall. become one marshallow. There's an edge between them and everything Yeah So I'm bringing this up just they don't emit X rays. No, they don't. L I checked. So I'm bringing this up just as a triumph of the Binging merical simulations to understanding the universe. And you made a career of doing just that. One of another great mysteries that we had to figure out wasas weird Galaxies had weird things going on in there in their centers And They give off a lot of energy and a lot of different wavelengths. And we came up with the unpoetic name, active galactic nuclei. Or quasars for the brightest ones. Especially of late. This has been a big part of your your objects of affection U it's one strand of my research, yes. Oh, just one strand. Just one strand. Yeah. And so So tell me about AGNs, what's the latest on them Well we all have black holes They all have black holes. That's what makes them so bright Because black holes are the brightest objects in the universe. This is where you come in and say, how could a black hole be bright? Yeah, how could a black hole be bright? I don't understand.. And is there a way for the black hole in my soul to brighten up as well.. Yes, there is. Eat a lot Because that's how black holes get bright. So You have gas, and we have already established that if you squeeze gas enough, it gets really, really hot. And if it's really, really hot, it emits a lot of radiation as the fourth power of the temperature And so what is better at squeezing things than a almost extremely tiny, extremely massive object, like a black hole So You have a black hole in gas and particularly in the centers of galaxies, there's a lot of gas because it all gets swept into the center as you wish the vacuum cleaner would do. But anyway. So here it is, all this gas falling onto the black hole and there's not room for all that gas to fall. so it gets squeezed and squeezed and squeezed until it reaches a billion degrees And I wasm just going clarify. so far No, thank God. Okay. Okay Of course. So when it's that hot, it's emitting in the x rays and the ultraviolet and all that light is coming out And that a lot of it gets converted down into the visible by running into dust clouds and stuff. And in on that if you have an electric stove When it's off Yeah, it just it's just off. Oh, it's emitting in the infrared. Yeah. just mildly, but then you turn it up a little higher And then it feels warm, emitting more infrared. and then it becomes visible. But it's deep red. Yeah, it's emitting visible light, but also still emitting all more infrared than before. But it kind of stops there But you keep cranking it up. if you had to get orange hot. Wait, so you could have like a black hole in your kitchen. Well we're getting there. Right. Not a good idea. Right. X ray emission is unhealthy for human beings. Ohold got it. Y. So you keep turning it up if you could It would then glow white hot then blue hot. like a welding torch. Right. But then that's all you can see, but it'll keep what's beyond violet t's cool. Yeah about. And now you're getting your sun burns. Yeah. And so at a billion degrees, you are way. You're way off into the X and gamma X rays and gamma. So you don't wan to be close to one of these. Okay, so hence the word active and active galactic nuclear. So these objects are literally the brightest objects in the universe And so we can see them. across the universe out to You know, ninety five percent of the distance to the B. When you're looking across the universe, you're looking back in time. So ninety five percent of the distance back to the B Bang We can see these things '' show offffs Totally. The show off little of the milk galaxy. of the universe. Well the universe The Milky Way does have a very massive, supermassive black hole in its center, but it doesn't get a lot to eat. so it's a kind of a wimpy dim little. B then where we've whereere we ever equation. there is actually evidence that quite recently, like just five million years or so ago There was a much brighter outburst from our own galactic black hole. And there's now a shockwave like running out of the galaxy. That's how you trace it, I guess. Yeah. ye. It was first discovered using the Fermi Gamma ray satellite Yeah, but is our black hole do we have black hole envy here? Oh y. We only have a million solar masses. The biggest quasars can be a billion solar masses. one thousand times bigger. So ye, it's embarrassing because like once you go big black hole, you really don't go back and that's like something that That's right astrophysicists That's right. Black holes do not give up mass easily Putting them on a diet takes a very, very, very long. Wait, can you tell me the size of these black holes in like the the like continental United States analogy? Oh yeah, sure, sure. So a billion solar mass black hole. It's like the solar system right is a little smaller than the solar system. A stellar mass black hole one solar mass is I want to say kilometers? Yeah I think that's right. Yeah. A mile A mile Got it. It's not as big as central Park. Okay. Yeah, and if Earth were a black hole, which would never be. But if it were, it would be the size of a plumb. A marble. Oh gosh. down there compress. Yeah, yeah, so compressed. But But while the solar system is big, that's tiny compared to the whole galaxy. and gas clouds are way bigger than that. Oh, so much bigger. When you talk about funneling them down to something as small as The size of our solar system. I mean, your average gas cloud is let's say a million times as big as the distance from the Earth to the sun. Space is big big. Yeah Sace is like angeringly huge. So. 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Plus, Apple Pay doesn't keep transaction information that can be tied back to you, or sell your data to third parties for marketing or advertising purposes Shop with confidence when you check out with Apple Pay. Terms apply Paramount Plus is now the home of all your BET favorites. That sounds nice. withith all new episodes of all the Queen's men. You stand up when you talk to the quQeen. Plus a whole new world of movies like Gladiator two. I must have power. Original series like The Shy. Life comes at you fast, whether youre ready for it or not. In live sports like UFC.believable New home, Welcome to Paradise. Same family. That's all that mattericed to me. Your B andT favorites are now on Paramount Plus, and suubbscribe now R Ban Reynolds here from MidMobile. I don't know if you knew this, but anyone can get the same premium wireless for fifteen dollars a month plan that I've been enjoying. It's not just for celebrities, so do like I did and have one of your assistant's assistants switch you to MintMobile today I'm told it's super easy to do at mintMobile d. com slash switch. Up frront payment of forty five dollars for three month plan, equivalent to fifteen dollars per month required. intntro rate first three months only, then full price plan options available. taxes and fees extra. Feful terms at mintMobile d. com You have not stop there, of course You have explored The formation of planets in these environments. So I started out by working on the formation of planets around normal boring stars. And I went so far you all care about? Well, I would think so, but you're bringing up weird planets. Okay. Okay. So I started out just thinking about the thing we care about, how did the Earth form Yeah. And I went so far as to hire a postdoc, Vladodyimir Lyra. to study this with me. And we were going along, perfectly happy, studying planets moving around in the protoslar disk and He made the mistake or maybe the very wise decision to talk to some of our city University, CUNY colleagues who are doing research here on AGNs. Oh, okay. Okay. on the discs. because we have here in our department, We have many frequent visitors from nearby universities with resident interests.. In particular, we have an NSF funded partnership with CUy which NF official NSF official to bring students and faculty from campuses across the city too do research here at the research intensive American Museum of Natural History. Is ever what pays for the pizza every Thursday? seven boxes of pizza come in People people only think when we're eating. what's a favorite topping of the astrophysicist community? Is there like a way I believe we may ensure that all diets have an option. Okay. ye. Okay. But back to AGNs, which are kind of like pizzas because they have discs very flat distributions of gas and dust around them 'a stuff falling onto an object If that stuff can cool off like gas can radiate and cool off It will form not a ball around it, but a flat disk. Same thing happened in our solar system. That's a rotating planets It's a rotating disk, not like a pizza. but like a pizza bean made. We like a sushi conveyor belt. Let's stick with the pizza. I hate those because that means the sushi went in front of the a lot of other people ye from a big Japanese scandal so you've got this flat disk And there's stuff accumulating in the disk. It gets dirty and dusty and that dust starts stick together And well If you're in a normal disk around a normal star like the sun, which isn't quite normal. It's bigger than average. there it makes planets, like say, this one that I can observe under my feet. However If you're in a disc around a supermassive black hole hundred million times as massive as the sun is an awful lot of dust in that disk and it's awful large. and you don't form Three planets or eight planets You form a million planets. So you made a million planet star system Planetary system Planetary system. Planetary system. Around a black hole. And this was a paper that we just had accepted a couple of two weeks ago. I got breaking news.. Yep. Okay. Although I will say so Buprendra Mishra was the lead author on that. How many authors are there? Let's see. I think there are six. So this is typical when you have collaborations. Absolutely. And some of them are cUy. Some of of them are cUy McCerny University of New York. Yeah. Barry McKernan and Soavvic Ford, Vladodyimir Lyra, who was a postdox. Ford is named for a character on Star Trek. Well, she named herself for it. Oh. I's got to say. publishes figurered that out. parents know, she did. But I think it's official. I mean, I think Oh yeah, she publishes under that. did o Soavvic for. Soavic. Yes, yes, o. Anyway, we showed that if you take standard planet formation theory and this is the same trick that Flaud Barian Soavk did fifteen years ago to realize that black holes could move around like planets. If you take standard planet formation theory and apply it to the dust, You find that it is very liable to go through all the stages that you would go through to make Plets except they're really big planets because there's so much dust. So how big how big are we talking? Yeah Jupiter mass, solid Rck planets. exxcept they're probably not rock because they're probably degenerate in the center. W away. So so our Jupiter is big, but it's mostly gas. It's a mostly gas., you can make a Jupiter sized planet that It silicates M Ouch So doeses that mean also that it's gravity is like extra annoying? Yes. Got it. Be it's extra annoying being like strong. Yeah understood that. Yeah we totally understood you mean. totally. So the just need to translate your' absolutely right. becauseuse the gravity at the cloud tops of Jupiter, we won't call it the surface, but at the cloud topops of Jupiter is quite reasonable. It's not far off from like grav times gravity. No, no, no, no. Not even. It's closer, it's gravity because Jupiter's so big in low density. But the gravity at the surface of one of these monsters perhaps be ten times Earth's gravity. I don't know. I haven't done the calculation. But it's an easy calculation But you're the same density and, you know, ten times the radius. We don't expect to find life on any of these because there's no home star to give I nourishing energy to No, it's rather worse. There's a home center of the accretion disc glowing in X rays and gamma rays. It will provide plenty of energy, but it might not be in a form conducive to life as we know. still to biology would be my Is there a biology that we don't know of that could maybe handle it? Is an excellent question that we don't know the answer to. is the Hulk biology. a Gamaay bolog Yeah Gamay. you add the Hulk into your simulator and see what is he doing? We're gonna have to get his specifications Yeah yeah I want to see this. So if all you need is dust, which are the larger molecules a larger gathering of atoms Minerals. Okay. These are silicates. These are dust like kind of like we find on the Eth, except it formed in space. Even though space is, as noted, very large, the rocky atoms of silicon and oxygen and magnesium tend to find each other. and once they find each other, they stick together And so they form little tiny dust grains like a nanometer in size and deep space. But when you collect all of them together, whether it be in a protostellar disk or a supermassive black hole disk U They can find each other and stick together. And actually that's something else I've been working on recently is showing that they might be a lot stickier than people have thought. So when they stick together, they stay They appear to stay well, until they get big enough and then they break apart when they slam into each other. And that's actually's a quest process. That's a big question in planet formation theory is how do you get them to stop beating each other up and fragmenting Yeah, because is it also, I mean, partially what you're describing almost sounds like a sandcastle. Like they're s sort of sticking together like a sandcastle. is an excellent description of an asteroid We call them rubble piles, but it's really a sandcastle. But so that so they're pretty They' Fragile. Yeah. They're totally fragile. How did we learn this? Back thirty years ago, a comet swung too close to Jupiter, Cet shhoemaker Levy nine You're supposed to not just make faces shoemaker This is a this is the first ever Observation of a comet slamming into one of our own planets. Yes. Yes. Or do you memorize all of the comets? No J the name popular ones.'s just a popular ones. Be I'm very impressed if you had them all down. right, no, no, no. being impressed. I am no longer impressed. Go ahead. Very good. Back as you were put in here that duo. By the way, the Shoemaker Levving nine Okay. It's really shoemaker, shhoemaker, L me. other athers that they're active Bunch Oh yeah and that collaboration had a leftover asteroid They named in my honor Y. Okay, I knew you had an an. I didn't know' was a shoemaker leave. It's a shoemaker leave. And the plaque is right up there on on Sorry, quick question. who decides these things is the discor? The discoverer, but it has to be approved. Okay can' you can't be rude. So was that That's'. The trio. That's how fertile a discovery group that' Gene Schumaker, Carlyn Schumemaker, and David Ley. and David Levy. Yeah. They've discovered comets and asteroids and all that kind of things. And Ge Schumemacer also in pretty much was the originator of the theory of craters What happens when something a big rock slams into a planet? It makes a crater. He described how And so that's this sounds obvious. I know I was just going to say like I can also ask my seven year old daughter about the theory of craters I come up with the same That's how that's how fundamental his work was, because before Gene Schumemaker, people looked at the moon and saw volcano craters. Right. They' not' not okay. Every crater was a volcanic caldera Yeah, but Cater Lake They're not completely crazy to think so. Well, Crater Lake is a volcanic caldera. Right. They're not crazy to think so. They were just wrong. It's possible to be that makes complete sense. You're just wrong. Okay. That has sence all the time. It's very frustrating. But the reason is The argument against them being asteroid was every crater is a perfect circle on the moon And no one is thinking asteroids are coming straight in Surely some are coming at an angle. And if you' coming at an angle, you'd expect an oval. Right. Most of them should be ovals, but everyone was a perfect circle And so that's the tension between the two arguments in the two camps And it wasn't until we had like we could model. Well until Ge Shumemaker came along and said, no, they should be circle. Noone had demonstrate on a comp with a computer simulation that a high speed impact When it hits, it explodes. It fapores. Yes that explosion makes a perfect circle Even if it comes in at an angle. Okay, but we're off the topic, which is that when comment shhoemaker Levy Nine passed close to Jupiter, It felt gravitational forces from Jupiter But it was com by at a fair distance and those gravitational forces were not strong massive planet gravitational forces. They were forces equivalent to O eighth of an inch of water in Earth's gravity. How much pressure does that put on your plate Not much. That's all the force tore that comment. twenty one pieces. That's how weakly bound it was. And that's why I say Sancastle is exactly right. Oh I feel so smart right now. Oh great. Yes. I love that moments. You're welcome. Yeah. so just to show, there's still a huge frontier for us to understand these objects Yeah. And you got people, good people working on it including the guy that said when a thing hits another thing, it forms a crater. Yes. Yes. Which like I can't believe somebody ye, somebody had to do it first. bless that guy. Yeah Yeah. So we got questions from our audience to who been specifically include to your research profile. Okay. And the questions will emanate from that So what do you have here for us Nik. I haven't seen the question.re haven'ten me' not seen them. I've seen them. I think they're great. Here we go. Tatiana here from Ottawa, Ontario. I'm fifteen years old and finally asking my first Star Tal question. Cratulations. My question is what are and how do supersonic Turbulent flows and magnetic fields regulate star formation inside molecular clouds. How many hours do I get? if she's not done, do they work together to stabilize the process? or does their interaction create chaos Yes Yes and yes. Yeah, naively it feels like that would just mess up the whole thing. Absolutely a coherent in out of this, aren't you? Stars. Stars. Stars. Okay Yes, the turbulence stirs things up, and it also squeezes some of the gas And so the squeezed gas gravity can take hold and start the collapse process. but the stirring prevents more gas from getting grabbed by gravity and collapsse down to form stars. So it's both, both and the stirring actually wins. so the more turbulence you have, the less star formation you have. Okay, but when you have a little pocket that's slightly more dense, That attracts more material that makes it even more dense. and so it's a runway. It's a run. once you onnce you get started onnce you get out of the starting gates. Yes. Okay. Then what happens is that as you start forming stars, the biggest, most massive of them pump huge amounts of energy back into the gas, whether it be through jets or ionizing radiation, or stellar winds or ultimately supernova explosions, and that chases the gas away and then you don't get any more star formation Okay, now how do you know all this because I've done simulations of it and then I compared those simulations to what observers saw and they were were so bad. So if you didn't have observations to compare it to, you're just kind of presuming your results are real. I'm playing in the sandbox without any constraints. And then I can make embarks on Yeah I'm not with it. But you like so how much like what level of confidence percentageise is it? So o, so the point about constraints is important because otherwise someone else can come along and say, no, no, no, no, no, the magnetic fields are going to hold everything up and you're going to have to wait for the neeutral atoms to drift through the ions to ever, ever make a star Without observations, we can't tell who's right. because he can say, off course it works like this. I've written twenty papers on it. And I can say, but my programs don't show that. But well, you know, so I wrote my programs wrong. possible. and You just went too quickly past that. What you just said was that your naysayer could be right and maybe you your your software Hey wrong. Bugs in approximations. Approximations. Okay. We always every model has approximations. We don't know until until you compare to the observation. There you go And then you get a reasonable level of confidence. then you build up your confidence. And of course, then you argue about what the observations mean and whether there was noise in the telescope and you know what assumptions went into the interpretation of the observations. But ultimately, this is how science progresses. You come up with an idea And then you have to then other people come up with different ideas, you are about it and you settle it. reference the real world. Oh not a duel. Okay, sorry. We try to avoid that. and most. somebody's shot him in a bug for. but it's evidence that Arriving at what is objectively true in the actual universe is messy. Totally And so messy. so messy. and the strength with which you argue your point Ultimately is not the arbiter No, unfortunately. It might be easier that way. And it doesn't matter how articulate you are or how charismatic you are, we have ultim still have to win. Judge jury and executioner is nature. That is the agreement that people doing science have made with each other. It's an impplicit agreement.. onene hopes it's explicit, but is that we will settle our arguments ultimately by reference to ucible experiments and observations So I'm right and you're wrong. You're right and I'm wrong or we're both wrong. It'll be decided by more data or better data. That's right. Yeah. Okay. that That is the central ten of science. Where does the magnetic field come from the magnetic field comes from a Dynam Dynamo'os happen when you get some sort of stirring of charged gas or charged things. So like a dynamo and a power station, the charge is running through wires. And it's spinning. And it's spinning. Yes. And in the universe or in the Earth, the dynamo is turbulent swirling Magma deep down in the earth, that is kept molten by the pressure and radioactivity of the Eth And it swirls around and makes the Earth's magnetic field. and that's a dynamo Same in the sun, except there it's plasma In galaxies The charged gas between the stars forms a dynamo stirred by supernova explosions and by gravity. So if you didn't have the turbulence You wouldn't get the diam. You wouldn't have magnetic field. You would not have they have they go hand in hand. onene generates the other. Okay. It's like they're in heat and then they give Birth to this Sure, maybe I think you're stretching the field here. But if you stretch the field and twist it and rotate, you will get a dynamo. O, than you. Okay. So the first dynamos happen when the very, very first stars form Ever since then, we've had significant magnetic fields running around getting stretched and twisted and folded to make more magnetic fields. There we are. There we are. S move on to the next questionqu. Thank you for that. All right. Issmayel Vlddez here asking my first question from a Vignia de Mar, Chile, okay. Okay. In regards to stars and gas giants, if Jupiter were sufficiently massive, would the pressure Ignite W it's pressure, Iignnite, it's lighter Y. Furthermore, do the sun or stars in general share elements with gas giants like a rocky core, or is it fused gas all the way through? which sounds like a tough meal at Taco Bell? I don't know. Go ahead. Let me modify that just a little bit. if we had the capacity to dump mass intoto Jupiter C me ignite it one. Yes. He had two questions The first question is, if you increase Jupiter's mass, doesn it ignite? And the answer is yes. If you increase Jupiter's mass enough Like Well, if you get it up to about I want to say ten times the mass of Jupiter, you get the deuterium burning, the heavy hydrogen with extra neutrons. And that lasts for a little while, but there's not a whole lot of deuterium in the universe. It's like, I don't know, a part in hundred a few parts in one hundred thousand. So that you get a little flash of light, you know, for a couple of maybe a million a couple hundred thousand years and then it's gone And that's a brown dwarf And they exist and we've got one of the world's premier research groups on the topic right upstairs department R by Jackie Ferty. And because we just went down the hall to get Mortecai, right? Yeah ye ye. I traveled a long way. I want my per deo. In the Department of astrophysics of the American Museum of Natural History That's a brown dwarf. Now if you keep piling mass on and get up to in Jupiter masses Like eighty times that much. Yeah, eighty times the mass of Jupiter. Which is a little under a ten You could just dro Saturn onto it. No, that would be amazing to watch. but not nearly an. It still wouldn't ignite it. No, no,, Not even close. Not even close. Not even close. Well, so you as you said earlier, like something like that is just like a couple hundred thousand years. It's like dumb. That's what That's the brown dwarf. Don't dum. Okay. No, I'm just trying to understand becauseuse you made that sound like not nothing. It's nothing. It's fusion, but it's not a lot of fusion. Okay. w w way, way ways It's a flash in the pan. Yeahot. Okay. But if you get up to eighty times thenen you can ignite hydrogen. And there's a lot more hydrogen. That's what Jupiter's mostly made of. Then you've got a very low mass star. And very low mass stars sit there and simmer for longer than the current lifetime of the universe. So that will keep going And going and going That's way more than two hundred thousand. It's way more the life of the universe. It's like ten times the life of the universe. No a hundred times the life current life of the universe. Yeah But question. Right now, Jupiter iss a rocky core Yes. What happens to that rocky core? Becauseuse' kind of related to this question. Absolutely. Yes. Yes Let's down there. Let's go. Let's go. Bring it on. Okay. So what happens is it gets completely overwhelmed by all the hydrogen and just gets mixed in because the hydrogen is sitting there fusing. So you have a little tiny rocky core. Now the sun whyy doesn't it just vaporize the rocky core Yeah, That's what I'm saying. Okay, it's not rocky anymore. but it is the elements former the rock core formerly known as rocky, are now part of the fusing vaporized hydrogen in the center of the object because it's now, you know, far hotter than anything any rock has any right to withstand. R So' it's rock rock. That's right. Now remember the sun also has silicon and magnesium and aluminum and oxygen in it. It's just all mixed in with the hydrogen. Right. So yeah the sun You might think would have a rocky core the right Jupiter did, but for that same reason, it's all It's too hot. It can't be anything other than loose atom. It lose ions and electrons even. canan't it even be atoms. Except on the very surface. an atom is a nucleus plus electrons. Yes. All the electrons are gone. Yes, ye. In the center, they're all gone. They're just roaming freely away from their parent atoms. Got it. Here's yourQ. Yeah like they're having a rebellious phase. they are long gone. neverever to return. N to return. They're not just like tepeeing their geometry teacher's house or something. No. They have gone., that's a thread Toilet papering? Yes, haveave you done that? I have. I tepeed once in in my your day story of the day. your offspring. I'm afraid we didn't do that in the center of New York City ' it's six story apartment buildilling You're just you're just doing toilet paper on someone's door. And it's a lot less, you know. satisfying. Yeah. I can't imagine This Father's Day when you ship UPS air at the UPS store, your items arrive on time with your money back, guaranteed at no extra cost. It's like the father of all shipping services. It shows up to the airport way too early, just to play it safe. It's over protective about all the things that truly matter, and it's always prompt, especially to be with family, making your first choice to celebrate your dad Shipip UPS air with our money back guarantee exclusively at the UPS store US retail locations. Visit the UPS store. com slash air shipping forpool details, terms and conditions apply We famil has more fun out Disney World L like me Bapa, he's super serious. But since you met Goovy? G He's been laughing all day. Or my sister. I never thought she'd try out the fast rides But Space Mountain was her favorite And me I didn't think anything could feel so special. The memory is made at Walt Disney World Resort, That's Bura Mahia Hey, I just Venmoed you for Rnt. Nice. Now I can instantly spend it whether I'm checking out online with Venmo or using a Veno debit card. Say more. More exactly. Because the more you do with Veno, the more you get, Like earning up to five percent cash back with Veno stash on a bundle of brands. So, order more pizza? The math demands it. Get the Venmo debit card Fimmo stash bundle terms and exclusions apply. See terms of VimMo. me slash dash terms. Vimmo check out notot available at all merchants. VMo Master card issued by the Bankcorp Bank NA I'm Nicholas Costella, and I am a proud supporter of StarTalk on Patreon This is Star Talk with Neil Degras Tyson We for few more questions. What you have? Okay, let's see. Hello. How is dark matter incorporated into your simulations, random distribution or what? sorry, and this question is from Ben Grund Great question and the answer is Any which way I can. So sometimes we actually put in particles in the simulation and watch them roam around under the force of gravity. And well, they're very massive particles, but they still behave like dark matter because they don't interact with the gas except by gravity. Other times you just said, since we don't actually know what dark matter is, Oh, no, no, no But we're not even going there. No't, but you know it has gravity Yes Your simulation has to get it somehow. So you sprinkle in You invent a particle that interacts only by gravity and has enough mas ennough gravity to match ark matter Obsorb dark matter. Okay. Yes. So this is as they say by fiat, you do this. Does that No I mean, you understood what any of these things were I could weigh in on if you used fiat correctly. I wouldn't say it's by fiat in the sense that The whole simulation, by that definition is by fiat. Right. I've added in a field of gas, I've added in star particles. So it's just one elements with the simulation. It's a way to get a source of gravity Wet worry about it after that. It behaves like dark matter.. The simpler way to do this, which I also sometimes do if I can get away with it, is to simply put in a gravitational field that reproduces the dark matter distribution and then let that handle it without having to actually do trrack particles withithout having to track particles pay attention and do accounting and get bugs and all the rest All right, so is it smoothly It's it's aooth It's smooth if you're on a subgalactic scale, but if you're on a, you know, know galaxy for forming scale, It's very, very clumpy because the clumps are the galaxies So in that sense,, you know, when I'm simulating the formation of the first galaxies, then we're seeing big clumps of dark matter that the gas falls into and then you've got a galaxy. So I've heard this, I think it's right that Dark Matter, whatever it is, is so an. that when you just when we look at and describe stars in galaxies, this is the froth. on an ocean Well, one sixth of the mass of the galaxy is in anything visible stars, planets, gas, comets, all of that, one sixth of the mass. five percent of the gravity is from dark matter. you only know what it is We know it exerts gravity and we know it doesn't move at light speed That's why it's cold dark matter. But is there like an area like that doesn't have any? like how Wyoming doesn't have people? Like is there an area of the galat like there's no Wyoming doesn't have people. Voids don't have dark matter. while clusters have lots of dark matter. and filaments have well, intermediate amounts of dark matter. They're like interstates Okay. So ye it's c It's so evenlyed. It's absolutely not even unse. not the universe. R. That's why we call it the cosmic web because it looks like spider webs like with thin filaments and then big spaces in between Right. So web is we say web now, but I remember A cross section of a sponge. Does a sponge still work as a sponge still works Yeah Yeah in sort of areas around in places where you're intersect. These days we usually talk about webs. Webs. OkayK, that's fine Ditch the sponge. I was kind of into sponges though. I mean I know You anology for the interstellar medium too. Yeah. You know, Chris McKee and Don Cox arguing about is it a sponge or is it little round clouds? I had a cameo in SpongeBob in b. I was Neil De Basse, Tyson. Oh, Astrophicicist So I just thought I I'm sticking a sponge. You got it. Okay, than. You can have Thank. The cosmological spin. Yes, thank you. Thank you T time for a couple. Okay, let's see. on a roll here. Yes, M. So Gavin Bamber from North Vancouver, please visit, they add. How long does it take to form a star or a planet? Is it the same process? We're both in the same stuff? O, Okay. I believes the answer is yes and yes And so how long does it take to form a star The main formation phase when most of the stuff comes down is maybe one hundred thousand years, but it trickles along hundred thousand. Yeah, that's like the m accretion phase. But it's gonna trickle along with a disk and accretting more mass and forming planets mion a couple of million years. So you'll form the star before you form the planets Well, that's an ongoing controversy. That was the idea that used to be the idea wouldouldn't that be the case, right You would think. But nowadays, the more we examine the question, the faster the planets seem to form. And so now I would actually say that the first planets formed during that main accretion phase very, very fast But then You continue to form planets and planetary like things for several million years. And what's in a disk. In a disc. It's all dust and gas I have a decretion disc right here. Yeah ye. If you want to get brighter, eat more Like the quas are. That takes so long. It just like everyone has to be really committed to that plan for it to form. You know what I mean? Because it takes a few million years. Oh my gosh. Yeah On the other end, where are you gonna go? You're stuck in this disc doing it. Let's get it going. Eventually we'll have an Rb's here or whatever. Yeah ye ye. Well now the development of Rb's takes a lot longer. That's billions of years. Observably. as Carl Sagan said How do you make an apple pie? Just start with a big bang Yeah. Go find the chicken Okay timeime for another question. Yeah let's do it. After all the model runs, how often do planets form with a satellite as large by percentage of mass of the planet as our moon? Good one That's a very good one and the answer is that the computer simulations aren't high enough resolution to really get a good answer to that yet And so that is a current research question. L meaning we don't No, but but we have all these planets with wimpy moons. Yes, right? Yes. So we already know. Well, observationally, we know in one planetary system with one set of initial conditions that moons like the Earth are pretty rare. And that's all we know. How many planetary systems do we know of it's growing now six thousand counting. It's growing. It's growing fast and it's going to keep growing. And we don't know if any of those planets have moons because observationally, we haven't been able to see them because it's really hard to see a moon around a planet. It's already really, really hard to see a planet. muchuch less a moon. And David Kipping up of Columbia thinks he's found a moon, but everybody else is staying on the fence and saying, maybe it's. David Kipping, we've had him on Starc. I'm sure you have. Yeah. She's got a lab, Oh the cool world lab. Yes, whichich is pretty pretty cool. And he's got a podcast. Yes. Which funds that lab. cool worldy. Your simulations will sometimes see like a hint of a moon My Well, I don't do those simulations, but our simulations, the fields You can make moons and we know I mean, we certainly know how to make the Earth's moon slam a Mars size planet into a Potor. and that works shockingly well. as evidenced by the Apollo astronauts bringing back rocks that had the same composition as the earth. Because they formed Be they went to the mooon to begin with. Yeah from the Earth to the moon. out it. Thank you. But that meant that the moon didn't form organically with the Earth It formed afterwards. Afterwards But now what the Earth is made of, of course, is also a mixture of proto Eth and I think they call it Aries, the Mars sides that I' No There U seeia. Isn't Theia the pro Earth and Ariess the Po Mon? Oh. I mean the pro I think C is the proto lam Cfirming now be announceet that the ancient protoplet that we collided with was Thea. Okay. So shockingly successful as this model that we even named the object thatt impact anymore. That's right. The impact object object, which is obliterated Yes and became part of the However gave it a name. Yes. howeveration So We can do those sorts of calculations for planets elsewhere, but to get the frequencies That's going that means a lot of calculation. We don't have enough computers to do that. Well, I love me my moon because our moon is the same size on the sky as the sun. So we get beautiful eclipses. No, I love it. Nobody else has eclipses like that At Jupiter, it's got moons, but The sun is far, the moons are small. notothing matches up the way our moon and our So what is it? The moon is F hundred times He sir And one four hundredth the size. Yep So everything ratios exactly exactly to the ye. And that's how you get eclipse chasers. Yeah. it's the greatest spectacle of nature. Secondly the Manhattan henge, which is also something you I love a Manhattan henge. Oh my goh. Thank you. That's because of you. Yeahah, I followed your dates. Oh, okay. So Mordic I time for one more question. Okay Let's leave it going It better be a good one And you're a good question answerr. You Is Andefficient? Okay, I will ramble. No on. Here we go. From Emil Rougeaot, who describes himself as a man who has forgotten what curiosity is, as once said before by you, Dr. McLo, eight to ten years ago. Qote, We live in a time where we have understood that the universe is far stranger than we would have thought. Have these thoughts changed over the years or have they made more problems for you U I would have to say that if anything, these thoughts have intensified. The universe is far stranger than we once thought and far stranger possibly than we can imagine Why do I say that? Because We live in a universe that is expanding that is accelerated that is forming stars planets, black holes, And it all came from a almost perfectly smooth Homogeneous hot. Very, very hot beginning That's not a story that someone a hundred years ago would have told. None of it ive exchange. I have books old books that describe the universe as an ordered a majestic place. Every in the right spot, everything in in stately orbit surrounding. And then we find out that things slam into each other. they blow up. It's full of turbulence. chaos. Yeah. I mean it's just a mess. Yes. Thank you for that cogent description of the modern understanding of the universe. can I ask you both a question then now, You're both in the field of trying to understand the universe better, right? solving mysteries at some level trying to understand the universe better. I guess if like doing a tight ten at the Chucklehut and Saboyen makes solves the universe in any way, I might be in that business. But does it make either of you feel I don't know, bad that like the more you study the like more you find it chaotic I mean, let's just say it keeps me in a job I have a different way to answer this Yeah If the universe were more and more chaotic, requiring as complex laaws of physics to understand it then what are we doing? But the real majesty is that it's just a few laws of physics. They generate all that chaos dead m. generenate all that chaos. It's just a few laws of particle physics. that account for all the particles zoo that we know and love. Except for dark Matter. Except for dark Matter. We're not there yet. So so we're working on it. To understand the universe required a complexity of theorizing that matched it, then all bets are off. I'll just go home, you know go to the Bahamas, give up on it. But if foundational understand, like Mordecaai, you said all this without even mentioning that you're an expert in fluid dynamics.