Listener Questions 33: Questions from your kids!

00:00:08
Speaker 1: Hey, Daniel, what's your mental picture of a typical listener of our show? Oh, that's tough. I think probably there is no actual typical listener. You know, like the average number of children is two point four, but there aren't any actual families with two point four children. It'd be hard to have a point four child. Do you think there's a big range like young and old, short doll? Yeah, I hope so. I think so. You know, we probably have atheists and spiritual people. We have scientists and salespeople, we have teachers and students and cartoonists. Emphasis. Well, let's not get too crazy here. Why do you think the audience is so very well? I think probably everybody out there has questions. You know, it's just part of being human to be curious. And if you drive a truck, or design buildings or lead a church, you still want to know answers to the biggest questions in the universe. Yeah, Like, how did a cartoonist and a physicist end up with a podcast Mysteries of the Universe? Hi am for handed. Cartoonists and the co author frequently asked questions about the universe. Hi, I'm Daniel, I'm a particle physicist. And a professor U c Irvine, and I was pleased at Punch to see our books called out in the New York Times last Sunday. Wait what Yeah? They had an interview with Moe Williams, one of my favorite authors and illustrators, and asked him, what are you planning to read next? And he said he had just finished our book frequently asked questions about the Universe, really enjoyed it and was planning to read We have no idea. Oh my goodness. We got a shout out from a cartoonist about a book about physics that's crazy. Yeah, and he described it as breezy yet content heavy, which I think kind of nails our style. Yeah. It's better than the being heavy and with greasy content, I guess exactly. And the book itself isn't even that heavy, right, Yeah, especially if you get the book waste nothing just a feel like crons. Welcome to our podcast, Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we tackle the heavy questions of the universe. How big is it? How much mass does it have, how does it all work? How long has it been here? And for how long will it keep doing its whole universe thing. We dig into all of those questions because we think everybody is curious about how the universe works, and everybody deserves to understand at least as much as anybody understands. That's right, because it is a pretty mysterious and amazing universe full of questions. Like kind of cartoonists understand the universe? I guess it seems like the answer is yes, if they read breezy but heavy books or write them. I guess right. I think writing them also helps cartoonis understand the universe. Yeah, and translating a physicist for the general audience probably also helps. Yeah. But it is a any incredible universe full of incredible and amazing facts to discover. But it all starts with asking questions first. You've got to ask the question before you can get the answer, right. That's the typical order of things. That is the typical order, And that's exactly why we always embrace the unknown. We know that discovery begins with admitting our ignorance and then diving into it, to asking questions about the things that we don't know, which will lead us down the path to understanding it. And it all begins with asking that first question about the universe. I think there's something about science and scientists that folks out there who aren't practicing scientists might not realize. You know, science isn't some monolithic institution that just like churns out results. Every time you see a result, it's because somebody has decided to dedicate their life to studying. Whether beavers brush their teeth or you know exactly how stars explode. It all comes from one person's individual desire to understand something about the universe. Right. But although it's not an individual effort, it's usually a team effort. Right. We often work in teams, but everybody who's on that team wants to know the answer to those questions. They've decided this is the most important question to be answered, and this is what I'm going to spend my life on. And there is a huge commitment to curiosity. But as you said, Daniel, everybody is a scientist. Everybody can ask questions about the universe. We can all observe it and even run our own experiments in our backyard or garages. Right, that's right. Check with your parents before you create a black hole in your garage, please, or your spouse. Don't create a black hole in your spouse. No, never do that. I mean, if you're forty year olds, I don't think you need to check with your parents about making a black hole. You might want to check with your city. They might have some kind of ordinance about it. But you know your parents need to give you permission. Are you saying you never ask your parents for advice anymore? They're useless to you now, Well, I ask them for advice, but not permission. I guess. So they're like, or, hey, don't create the black hole. You're like, technically I could, though, Yeah, do you feel otherwise? I feel like if people are telling me that what I'm gonna do is going to destroy the planet, even if I actually have the right to you, so I'm still gonna listen. Well, of course you're gonna listen. I'm gonna listen to their screams as they get sucked into my black hole. Although I guess your parents could technically still guilt you into not doing it. Yeah, that's called an emotional black hole. A bit of a relationship there. But parents and kids all have questions about the universe, and it's especially interesting to hear the questions that children have about the universe because I guess they haven't read as many books as other people exactly, and they come to it with a really wonderful sense of joy and wonder and curiosity, and also stripped of some of the preconceptions that adults have. So often their questions are really the deepest, hardest questions to answer, and so to be. On the podcast, we'll be tackling Listener Questions Number thirty three kid addition. Now, Daniel, are you sure? This is episode thirty three of our Listener Questions series. I'm about sure. Can you count to third? Three? Do we need a kid to come and help us. I'm a particle physicist. I'm used to dealing with like two particles interacting, three particles interacting. Anything about thirties basically infinity for me, right, anything above that is what chemistry? You say that with such derision admiration. Who doesn't like chemists. I'm just overwhelmed by it. I'm not capable of it. That means I'm impressed by chemists. You just don't have the chemistry with chemistry. No, I do not have chemistry with chemistry. It doesn't cause a reaction to you. No, exactly. My son is now taking high school chemistry and I'm trying to help him with his homework. So the last time I studied chemistry was also when I was in tenth grade. So you're like, good luck, I'm like, I hope nothing's changed in thirty years. I'm sure they've invented in new chemicals by now. But anyways, we love taking questions from our listeners, and especially from kids. Kids are the most awesome question askers they are, and we like hearing questions from our kids. We like hearing questions from your kids. So if your kids ask you questions and you don't know the answer, please write to us. We will help you dig into it. Send us any questions. You have two questions at Daniel and Jorge dot com. And so today we have questions from three kids and they range in topics from philosophical questions about the nature of of something this Thor's hammer. I'm looking forward to that one. And also we have a question about lonely stars. So our first question comes from Danica, who is eight years old. Hi, it's me Danica. I'm eight years old, and my question is what does nothing look like? Also, I'm a big fan of your podcast. Um, oh, that's awesome. I like act. She said, Hi, it's meet Danica. Like, I guess we know her, right, I guess so. I mean she has written into the podcast several times and I've answered her questions, so it's nice to hear her voice now. Well, Danica, we love that you listen to the podcast, and it's great to meet you or meet your voice at least for once. And it's such an awesome and deep and difficult question what is nothing and what does it look like? Well, she specifically asked, what does nothing look like? Can we answer as children and just say nothing? Next question? Oh? No, that's how it's usually answer things. It should be a title of our kid edition. If we have no idea, I don't know how you spell that either. Yeah, you will have to come up with some new molecules for that. But it is an interesting and almost philosophical question, what does nothing look like? I guess first of all, what would you describe as as nothing? What is nothing? That's really the heart of the question, what is nothing? And is it even a coherent idea? You know, in philosophy people talk about this question why is there something rather than nothing? And in that case, you have to define really carefully what you mean by nothing, and it has to be something that makes sense, you know, that holds itself together. That is like an option for the universe, that the universe could have been that way rather than this way with things in it. Because I guess there are different levels of nothingness that you can have, right, I could have nothing to do today, or I could have nothing in my pockets, or there could be nothing in front of you that I could see, for example, right, or you could have nothing to say about the topic or nothing. For an answer to this question, I think probably she's imagining physical nothingness. You know, she's in a room. It's got stuff in it, all right, So now empty the room, take all your furniture, all the chairs, all the posters, off the walls, so there's nothing in it, and look around, well, what is in the room. Then in that case, you still have air, right, so ump the air out of the room so that you're in a vacuum now, and I hope you're wearing a suit. I think this is sort of the direction of nothingness she's imagining. Or do you think maybe she's imagining like outer space where there's nothing or like a spot in space out there that doesn't have anything. No planets, no stars, no gas, no dust. Yeah, it's interesting because nothing is sort of defined by its opposite, right, no thing, so not defining what it is, you're sort of defining what it isn't. So to get to nothing, you have to like remove as many things as possible. So you take out all the stuff, you take out all the air, or as you say, you go out into outer space where that stuff doesn't exist at all, and you look around you. But you know, even out in space there are things. If you are somewhere in our Solar system, even if you're in outer space, there's could be lots of particles around you. There's the solar wind, which is constantly blasting protons and electrons out from the Sun. Of course it's filled with photons because you can see stuff. So even a random chunk of outer space, it still has things in it. Right. But we talked about in the podcast how there are spots in space that are pretty much empty. Right, There are sort of spots in space potentially that they have nothing in them. It's certainly possible to have a chunk of space with no particles in it. You know, you somehow get rid of them, or you find one where there aren't any. It's not required that space have particles in it, but there is another layer two space, right, Those particles in the and our ripples in the quantum fields that fills space, and those fields exist everywhere in space. Even if there isn't a particle in the field, the field itself is there. What do you mean it's there if it's not active, or if it's not rippling or anything, if it's just staying still, is it really there? Yeah. It's sort of like a parking lot. Right. You can have a parking lot that's filled with cars or doesn't have any cars, and you can imagine like, well, if there are no cars in the parking lot, then the parking lot is empty. Right. But a quantum field is a little bit different. These fields that fill space and fill the universe, they can never truly be empty. Quantum fields have a minimum energy states. So every chunk of space has quantum fields in it, and they can never really be at zero energy. So every chunk of space has some energy with it. That's why when the universe expands and creates more space, we say it also is increasing the energy of the universe, because space comes with these fields sort of as a fundamental element of it. That's interesting. Yeah, you're saying that the field, even if they don't have a particle or ripple in them, have some kind of energy, which means they're they're kind of We can get philosophical about what it means for the field to be there if you can't see it, because remember, you can never actually observe fields directly. You can only see fields effect on other particles, sort of like the curvature of space. You can't see it, but you can see its effect on beams of light that curve it. You can't see an electric field directly, but if you put an electron in it, you can see its effect on the electron. So some people argue that fields are just sort of like a mathematical construction. They don't even really exist. Everything is particles, And if you like to go that route, then you could say that every part of space is filled with a low level of virtual particles that are sort of out there, ready to interact with particles you shoot through them. Either way, there's something in space. It's not ever really totally empty, and as far as we know, these fields basically occupy the entire universe, right, is it possible that there's a pocket of space out there without quantum feld We think that they filled the entire universe, and the arguments we have for that are not very specific, but they're sort of broad and powerful. You know. We think that the laws of the universe, the laws of physics, are the same everywhere. We see no evidence for one part of space being different from another part of space. So it would be really strange if some chunk of space just like didn't have a field in it. That would mean it has different physical laws, you know, like electrons can't get pushed by electric fields in that part of space because there aren't any electric fields. Light can't propagate through that space because light is a ripple in the electromagnetic field. That would be really weird. The reason we believe that space is the same everywhere in the laws of physics are the same everywhere, are like well number one, that's the simplest thing. It would be pretty weird to be different. And also there are consequences of that. If space is the same everywhere, then there are symmetries, which leads to conservation laws, like conservation of momentum, and we see momentum is conserved, so that suggests that space is the same everywhere. Sort of a big leap there. So if you want to dig into the details of that argument, we have a whole episode about why is momentum concerned and Other's theorem which makes the connections between those ideas. M I think what you're saying is the quantum field is sort of part of our laws of the universe, or what we think are the laws of the universe, and so to imagine a spotting space without quantum fields is like imagining a space without any laws. Were different laws? Yeah, alright, so, Danika, I guess there is no such thing as space without with nothing in it. But you can also ask if you have to have space, like you can push it one step further and say, well, maybe you get rid of space. Is it possible to have part of the universe without space itself, because that's the way to get rid of the fields, right, right, Because we often say that spaces is a thing, right, it's not space is not emptiness or an empty space. It's like a thing, right, Yeah, And that's something we don't know if it's possible. We did a whole podcast episode about what is space? Where does it come from? Do you have to have it in the universe? And modern thinking is that space itself might be emergent, It might not be fundament rental to the universe, like pies and politicians. You don't necessarily have to have in the universe. It comes out of complicated interactions of other things that do exist. That might mean that there are scenarios where you have a universe that doesn't have space in it, that space itself comes from, like the weaving together of quantum states via entanglement into some fabric that we now recognize as space but didn't always exist. You're saying that there could be and maybe not in our universe, but maybe a universe out there where there's all nothingness then or earlier in our universe. Maybe that space wove itself together at some time in our universe, and before that there wasn't space, And then you can ask like, well, maybe there was something else. There were these quantum states, so that wasn't nothing, but it's not space in the same way, and so you couldn't really look at it, and you can't like look at nothingness if it's not in space. With you, because looking at something requires like shooting light at it or seeing like come from it, or some how probing it. There's no space, then you can't like interact with anything in any way. So it sort of like pulls apart the whole question. Well, I think what you're saying is that space is something, and so if you had a universe without anything in it, would it still even be a universe? Yeah, we don't know if that's possible. But if you were in that universe, you also couldn't look at anything because looking at things requires space. Well, let's say that we give Donka superpowers and she has the ability to do anything with her mind, and she imagined the pocket in front of her, a little blob in front of her that has no space in it. What would that look like to her? Probably just black, right, because nothing would come out of it. Definitely, nothing would come out of it. But I think there might be an inherent contradiction in that definition, right, you're talking about a ball that doesn't have space. You're define in coordinates and location and relationships between coordinates. That's really what space is. So you're like defining a space that doesn't have space in it. Well, I mean, she has superpowers, so she can do whatever. Then asa she creates a little bubble that if you go into it, there is no space in it. Well, she has superpowers, then you know, she can make it look like whatever she wants. It can look like Captain Crunch or ice cream or purple dinosaurs. Well, we still need to follow the laws of physics outside of it, right or at the border of it. Yeah, but if there's no space in it, then nothing can propagate through it, and so nothing could leave it, and so it couldn't look like anything, right, So it would be like if it was just in front of her, it would just look black because no light can come out of it, and any light that goes into it, which is kind of like disappear, right, Yeah, exactly. Maybe a black hole has nothing in it. In fact, we don't know if black holes have anything inside them. It might be that everything that falls into a black hole is sort of smeared onto its surface and they have no interior. All right, Well, I guess that's sort of an answer for Danica then, is that it could look like anything you wanted to, but most likely it would just look black because that's how your brain interprets when nothing, you know, no light enters your eyes, right, so there's nothing, no light coming out of this blob, then it would just look black to you, even though it's not really black. It would just look black to you. It would look like a lack of any signals. And that's how your brain portrays a lack of information. So you're saying it would look like nothing, then I'm saying nothing like that. All right, Well, thank you Donicus so much for that question. We're so glad you wrote in with it. And so let's get to our other questions from our other kid listeners, and the next one is about Thor's Hammer, which I'm really looking forward to as far as let's take a quick break, all right, we are taking questions from kid listeners, and surprisingly they're not about asking for more screen time. They already know the answer to that is because it's a podcast, there are no screens. But our next question comes from Grace, who's twelve years old and who lives in Vancouver. Hi. My name is Grace and twelve year old shame Vancouver, Washington. I was wondering if you could help me with Thor's Hammer. It said by some that Thor's hammer is made from the matter of a neutron star. If that's the case, would approximately one point five leers of densely packed neutrons from such a star have enough gravity on its own to even stay together if removed from its original star? Or would it simply fall apart because it doesn't have enough of its own gravity? Okay, So I also have a follow up question. If Thor's hammer stays in one piece, how much gravity would it have. Would the gravity be so great that it would suck the earth around it, becoming Earth's new core? Or would it sit in the corner and collecting more dust? My dad said destroy the earth, but I'd rather it's sit in the corner and collect dust so I don't have to clean often anyway. I bet you can do the math and science can answer the question. Awesome question. Thank you Grays, And the first answer is yes, I would love to help you with Thor's hammer. I feel like we're worthy of lifting meal near. Should we have her ship it to you? Do you have like a UPS number she can use? Oh? My goodness, what would the shipping cost her? Doors hammer? D I guess I can just hold on my hand and hope it comes to me. Yeah, that's the true test. I think. Actually UPS has a maximum shipping limit. Remember once my dad tried to order an old fashioned anvil and UPS refused to deliver it because there was so many hundreds of pounds. Yeah, you should have to hire a truck for that kind of thing. But yeah, maybe UPS has some restrictions. You know, no explosives, no batteries, no, no magical hammers. Are you saying that the Marvel Cinematic Universe is based on magic instead of science. Well, isn't science at the end? Magic? Magic is everything we haven't yet understood by science. Wait wait what it's magic until you understand it and then it's science. Well this is an interesting question because I do remember hearing or reading that Thor's hammer is made from neutron stars, right. That was in one of the movies where he like there was some kind of factory around a star and he had to like forge a new hammer or new X. I'll trust you on the canon of the Marble Cinematic Universe. I have heard that it's at least as dense as a neutron star. I wasn't sure if it was actually made out of neutron star material or not. Well, I guess let's assume for this question that it is made from a neutron star. That would be a pretty amazing feed, right, that would be pretty amazing since the interior of a neutron star is a very hot, very dense, very unpleasant place, even hotter than California right now. So maybe step us through. What is a neutron star, Daniel? So, a neutron star is a very massive, very dense remnant of the explosion of a star. You have, like a normal star, it's burning in its lifetime, it's gravity pushing in and pressure from fusion going out, and eventually it accumulates so much heavy stuff at its core from fusion that gravity wins and it creates a collapse of the star. This shock wave rushes in, which then creates very hot, very dense, very high temperature conditions which ignite fusion very very rapidly, which then explodes out and you get a sup renew sometimes and would you have left over at the core. It's very dense object, this neutron star. They're about ten to twenty kilometers wide and one to three times the mass of our sun. Sort of a lot of uncertainty there in those numbers. But they're incredibly massive for their very small sizes. Right. It's one of the, if not the densist thing in the universe. Like once they removed from a black hole. Right, Like, if it was any denser, if anything was more dense than a neutron star, it would probably collapse into a black hole. Yeah, a black hole is the only thing denser than a neutron star. So somewhere out there there's like a version of Thor with a black hole hammer that can beat our Thor's hammer. Oh whoa, whoa, whoa, whoa. You just gave me some huge ideas for a comic book storylines. Somebody write that thing up. But yes, neutron stars are like one layer above black holes. They're holding themselves together against the incredible gravity that's trying to compress them. If you didn't have the strong force pushing back out, they would just collapse into a black hole. But they get squeezed down. All protons and electrons get squeezed together to form neutrons, and you get this thing which is mostly neutrons, though we dug into on a recent episode, there's like a thin crust of other atoms, and at the heart of them, there's a very strange stuff going on. Stuff we don't even understand what happened to all the electrons that were in the stars. They got eaten, right, The proton captures the electron and gets turned into a neutron. It's the opposite of neutron beta decay or neutron decays into a proton and an electron. Force an electron back into the proton and it converts into a neutron. WHOA, the electrons got eaten, but doesn't they a total number of electrons and the universe have to stay the same. Can can you just eat an electron? You can't just eat an electron. You have to produce also an electron anti neutrino. In beta decay, you have a neutron which goes to a proton, an electron and a neutrino or an anti neutrino. You have to have an antiparticle there somewhere, and in the reverse process you have to produce the opposite particles, So there's also neutrinos involved. Keep the accounting of the number of electrons balanced all right? Well? In Grace's question, I guess if thorce hammer is made out of a neutron star. I guess then the process would have been that somebody went to a neutron star, scooped a bunch of the stuff that's inside of a nutron star, and somehow forced it into a hammer, which I think she estimates is about one and a half liters in volume. So how much would that way? Then the density of a neutron star, it's such that one tablespoon of that would weigh three billion tons on the surface of the Earth. That's something like two trillion kilograms of mass. So then you break out your leader to tablespoon conversion and that's about a hundred table spoons in a liter and a half, which gives you about three hundred billion tons or about three hundred trillion kilograms of matter. That's a lot of kilograms, I guess. I imagine, how does that compare to like the mass of the Earth or like the mass of the empire state building. Yeah, so it sounds like a lot, right, trillions of kilograms is a big number, but you know, the Earth is really really big. The Earth has ten to the twenty four kilograms, so the Earth is like a trillion times more massive. Than Thor's hammer. What about like the Empire State building or maybe like your typical mountain. So the Empire State Building ways around three hundred million kilograms, so that's like a million times less than Thor's hammer. So Thor's hammer is like a million Empire state buildings. Wow, So if you had a million Empire state buildings scrushing down to about the size of a coke bottle, that would be Thor's hammer. That would be the mass of Thor's hammer if it was made out of Nutron's dormitory exactly, if it had that same density. Well, that sounds pretty heavy. That means Thor is as pretty strong guy as is I guess Captain America because he lists to the hammer. Also, exactly, that super serium is pretty super So then her next question is would it hold together? What does that mean? Like, would it have enough gravity to hold together? Why wouldn't it hold together? Well, if you've taken it from the heart of a neutron star, then that neutron star has formed under special conditions. It's like being squeezed together by all the other stuff around it. There's an incredible amount of pressure. It's not just being held together by its own gravity. It's also all the other stuff. It's like if you take something and you put it deep underwater, there's a lot of pressure squeezing down on it, helping it keep it together. So it's not clear if you took it out of the neutron star if it would explode, like some things would explode in our atmosphere, but if you put them deep underwater, the water would keep them together. So I think her question is if you extracted this from the heart of a neutron star, where it's very very high pressure, would it hold itself together or would it blow up because it is under so much pressure in the neutron star. But I guess what if you've just formed it outside of a neutron star, Like if you just took a million Empire state buildings and scrunch them down together to form the hammer, would it hold together? Well, the answer is that we don't know, because we don't understand how matter organizes itself under crazy pressure. We talked in a recent episode about what's inside a neutron star, and we think that there's some crazy things that happened. We think they formed these weird states called nuclear pasta where first you get these blobs called nuclear nioki, and then they form these rods called nuclear spaghetti, and then sheets called nuclear lasagna. And these things are very very strong. So these are the neutrons that have assembled themselves into this new form of matter, you know, the way like particles can make gas or liquid or solid or whatever. These are emerging structures from how the little bits are getting squeezed together and interacting under these crazy conditions. We think you form these things called nuclear pasta, but we don't know what happens to nuclear pasta if you form it just out in space without the crazy high temperature and pressure environment in which it was made. One possibility is that it can't survive, that it blows up right explodes, that it's just an unstable configuration because the particles don't like getting squeezed that intensely. Another possibility is that it is stable, because simulations suggest that nuclear pasta might be some of the strongest stuff in the universe. We have examples of that, like diamonds. Diamonds you can only form under very very high pressure, high temperature conditions. Once you take them out of there, they're stable. They're like locked into this configuration that can survive even at the surface of the Earth, So we just don't know the answer. What happens if you make a sheet of nuclear pasta and then take it out into low pressure empty space. I see, it could be that it blows up, or it could be maybe like it forms something like a diamond that stays together. I guess if it blows up, why would it blow up? Like, why would it matter? Like being compressed that much? Is there something about the quirks or something that they just don't like being together that much? It might be that they do. We don't know that they do. It might be that they're very happy to get locked into this configuration. We just don't know. If they don't, it would be because there's some force between them. Right. The reason that things push against each other is because their forces between them. You push two atoms next to each other, and they will resist because their electrons repel each other in the same way. The quarks inside those neutrons could be repelling each other as well. But we just don't understand the strong force of those short distances as those very high intensities well enough to know whether it will explode. But if it it, it would because the strong force is pushing the individual corps apart. All right, Well, the last part of our question is how much gravity would Thor's hammer have if it was made out of nutron stars. So if we take a million empire sage buildings crushed scrunching down into a little cube, would we be attracted to it by its gravity with the whole Earth sort of collapsed around it? Would it start making a black hole? What would happen? It's a really awesome question. And so I did a few calculations. And you know, here we're talking about something that has three hundred trillion kilogram and so the force of gravity you feel towards this thing depends on how far away you are, right, because force gravity goes like one over distance squared. And so if you are like a kilometer away from Thor's hammer, then you're gonna feel a force of two Newton's which is like two percent of Earth's gravity. Well that's a lot too. Neutants is like a pound of force, right, So if you're a kilometer away from Thor's hammer, you would feel it, right, You feel a pound of force pushing you towards it. Exactly, You feel like two of Earth's gravity towards Thor's hammer. So if you drop a ball, it wouldn't just drop straight down, it would drift towards Thor's hammer. But still Earth's gravity would be the overwhelming force if you're a kilometer away, and then if you get closer, like say you're a meter away from this thing, then you're gonna be feeling two million Newton's which is two thousand times Earth's gravity. Remember, humans can survive like six, seven, eight, maybe ten times Earth's gravity, you know, like fighter jet pilots. Very very briefly, we're talking two thousand times Earth's gravity. If you're a meter away from this thing, so you would get smush basically, right, you would get smush, you would become the outer layer of Thor's hammer. You'll probably get torn into pieces. Right, That nuclear pasta would spaghettify you because the forces on the back of your head would be weaker than the force on your front of your head, so it would tear your head apart. So it would not be a pleasant experience to be a meter away from them. That's crazy. So if I have Thor's hammer and front of it, it would start to suck everything in around it, right, I mean the things a meter away from it would get sucked in with two thousand pounds of fourth two thousand times Earth's gravity, some more than two thousand pounds of force. Yeah, So then all the stuff it gets pushed onto it, which would give it more mass. That stuff would compress, and then that would attract more things. So it would just create a giant vacuum basically on the surface of the Earth. Would suck up mountains too, right, yeah, and it would suck Earth up also, right, the Earth underneath it is not that dense, so it wouldn't just be sucking from the surface, would be digging into the Earth. And it's really massive, so I think it probably would just sink into the Earth and become part of the Earth's core. Oh right, I guess because it's also being pulled by Earth's gravity to right. Yes, absolutely, so it would start to suck everything around it create a giant crater. But then the crater would start moving down towards the center of the Earth. Yeah. And as you get very close to this thing, the gravity is incredibly intense. Remember, gravity goes like one over distant squared And the impressive thing about having something so dense is you can get very very very close to it. If you're like a centimeter away from this thing. We're talking about twenty million times Earth's gravity, So the matter very close to Thor's hammer would get very powerfully pulled in and very very dense. So, yeah, be a runaway gravitational effect. Yeah, and it would probably shred matter, which would release a lot of energy to right, it would probably and it would also axillary things, and so it would be almost like an explosion too. Yeah. I think it might have enough energy to break chemical bonds and maybe to ionize matter to like pull electrons off of their atoms. Definitely not enough to like break open the nucleus because tider forces require difference in gravitational strength, and the size of the nucleus is just so small that gravity doesn't really change very much over the length of the nucleus. But yeah, it would shred stuff apart. It would create a whirling maelstrum of destruction as it sinks into the earth. Wow, would it destroy the earthy thing or would it just you know, create a big hole. Well, in the end, it's one trillionth of the mass of the Earth, and so it would sink to the Earth's core. In the end, it wouldn't really change Earth's gravity all that much. But I'm not sure what would happen at the heart of the Earth. It might continue to just compress what's going on at the heart of the Earth and might eventually just turn the Earth into a black hole. Wait, what it can trigger a black hole? If it can stay that dense and have that intense gravity, it's going to continue to compactify the Earth around it. If you teleported Thor's Hammer into the heart of the Earth, then the stuff right next to it would get compacted onto Thor's hammer. It would be even denser, which would increase the gravitational attraction, and so it's a runaway gravitational process. It might turn the Earth into a neutron star. Actually, yeah, that makes sense, because if it couldn't initially turn into a black hole, why would it turn into a black hole now? Just because I fed it a little earth fed it little as a little a pair of teeth, a little moose bush. Either way, it sounds like bad news for us, and so um good thing Thori's Hammer is not here on Earth. We think exactly, adding Thora's Hammer to your living room would not help clean things up. Although I guess if it's a fictional universe with magic and stuff, then I'm sure you know, the people who made the hammer put in some maybe mechanisms for it to not suck literally and figuratively, they're gonna really support the floorboards underneath Thord's hammer. Yeah, yeah, like somehow it's made out of material from a neutron star. But you know, maybe it has special you know, enchantments to make it all together and also not have that kind of gravity. Well, let's hope so. And then one day scientists in the Marble Cinematic universe will unravel those enchantments and understand the science of them, and then they'll be worthy of lifting mule here. All right, Well, thank you Grace for that awesome question. We think you're a superhero yourself, and so let's get to our last question here about Lonely Stars. But first let's take another quick break. All right, we are taking questions from listeners, and today we have a kid edition of our Listener Questions episode, and our next question comes from Derek, who's nine years old. Hi, my name is Derek, and are nine years old. I was wondering if there're any stars the universe that are not part of any gaxy. All right, thank you Derek for that awesome question. I wonder what made Derek think of stars that are not part of a galaxy. Maybe Derek and his family are trying to plan a vacation and they're looking for an exotic spot away from everyone else. Yes, you know, some people just like to be isolated, and you had a tough day at the playground. Maybe just curious. You know, it's a great process to think, all the stars I know of our in galaxies, is it possible for something else to happen? Could it be that stars could form outside galaxies? Just like asking basic questions about our assumptions. I think it's a great way to explore the universe. And I guess it's kind of interesting because at some point in human history, maybe not too long ago, we didn't even even know there were galaxies. Right. We thought all stars, which is part of the Uni verse, and there was just a big blob of stars that made up the universe. Right. Yeah, just over a hundred years ago we discovered the galaxies are a thing. They're floating in space, separated by vast distances. Rather than the whole universe just being sprinkled with stars. That was one of Edwin Hubble's discoveries. Yeah, and then we realized that every star we see in the night sky is actually part of a galaxy, of a cluster of stars, and if you look closely and far away in the Nice Guy, you see other clusters of galaxies. And that's how we sort of figured out that this stuff in the universe sort of organizes itself in galaxies. Right, that's right. Some of the galaxies the night skuy are a little tricky to see, but they're very dramatic, Like the nearest galaxy Andromeda is actually huge in the Nice Guy. It's bigger than the full moon. It's just not very bright, so it takes a special camera to take a long image of it so that you can see it. But it's really big up there. Yeah. And so I guess Derek's question is if you know the stars that we've seen the Nice Guy are all in the Milky Way, and we see other clusters of galaxies out there, I guess the question is are their stars that are not part of a galaxy? Yeah, it's a great question, and the answer is yes, there are stars out there that are not part of a galaxy. But we don't think that they were formed out there on their own. We think that all stars are made inside a galaxy, but then some of them are lost. So like between our galaxy and the next galaxy, there could be random stars floating around. Yes, we think almost certainly there are. In fact that scientists have seen them. We have spotted some with space telescopes. We've even seen one or two go supernova out in the depths of space. M interesting, I guess how have we seen them and how do we figure out they were not part of a galaxy. Well, you can see these stars with telescopes like Hubble Detective, the first one in seven. You can see that they're out there and you can see that they're not part of a galaxy. Just like literally out between the galaxies. You can tell how far away stars roughly by its recession velocity, by how fast it's moving away from us, and by measuring its red shift, and we could also compare it to near by stuff. So you just see these stars out there between galaxies. Yeah, because it's kind of hard to tell, right, because you just see a little pin point in the sky and start to tell if it's really far away or kind of close. Yeah, there's this ambiguity between things that are really far away and bright or really close and dim. All you're seeing is that point in the sky. It can be hard to tell. But we have some tricks to figure out how far away things are. One is how fast is it moving away from us? Because things that are further away from us are moving faster away from us. Also, we can look at nearby stuff. We can compare them to two things that we can calculate. We have like sephids, which are these special kinds of stars that how will use to figure out how far away things are. And then further away we can look at type one nice supernova, this kind of stuff. So we have a few like reference points this cosmic distance ladder to figure out how far away things are. All right, And so you're saying, if there is a star that is not part of a galaxy, you're saying it probably wasn't made out there in the empty space between galaxies. It was probably made in a galaxy. I guess my first question is why do you say that? Why couldn't a star form by itself in between galaxies? Will star formation requires sort of special circumstances. You need a big cloud of dense enough gas that has to be cold enough, so you need gravity, like gather together a lot of hydrogen in one place and then cool it down somehow so that the stars can collapse. Remember, star formation happens when you have a cloud of cold gas and then you have a little spot in it that's denser than any other spot. That spot now has more gravity than everything else, and so we can attract more and more stuff to it, and just like Thor's hammer that we talked about, that becomes a runaway process. It grabs more and more stuff. So that's happened. You need this big cloud of cold gas. And while there is gas out there between galaxies is just not dense enough, and it's also too hot. The gas between galaxies is moving really really fast. It's zipping around a lot. So you need dark matter to gather together huge clouds of gas into galaxies to create these star formation conditions. Right. I guess that's what we see right now, that in most of the space between galaxies there's hot gas. But I guess that doesn't maybe tell us that that there couldn't be earlier in the universe just a little cloud of gas that form into one star by itself, right, is that? I mean? Is that possible? Or I guess The same question is why didn't the universe have little small pockets of cold gas out there in between galaxies? Well, in some sense it did, right, Remember the galaxies formed smaller. You started with smaller pockets of gas which formed stars, and then those merge. So the history we see is the formation of a bunch of really small galaxies which come together to make bigger galaxies. So in some sense it's a definitional thing. You have a blob of gas which starts to form stars. You call that a baby galaxy, and then it merges together with other baby galaxies to become a bigger galaxy. Can you get a pocket of gas which forms a single star? You could, though it's unlikely because these conditions tend to form multiple stars at once. These clouds of gas are big enough, and when the conditions are ripe, they form many stars sort of at the same time, which is why you see, for example, so many binary star systems because stars are formed near each other and they're sort of together from birth. But it's possible technically to form a single star from a cloud of gas that happens to be isolated from everywhere else. It's not impossible. So it probably has happened somewhere in the universe, right, because I guess when the universe began in the Big Bang, it was all kind of random, right, there were huge blocks of gas here, but maybe there could have been smaller blocks of gas all by themselves somewhere in the universe. Yeah, it's definitely possible. But if you're looking at the stars today that exists and are outside of galaxies, we think the overwhelming likelihood is that they were formed inside existing galaxies and then ejected. They were kicked out, they were booted, they were voted off the galactic island. So it's not like a game of musical chairs where all the stars were like, all right, everybody find a galaxy, and then there was one star that gon trapped without a galaxy. That's the scenario I was trying to paint. But you're saying it's more like everybody got into teams and then the somebody got booted out sadly. Yeah, it's more like a corporate merger, you know, in two big companies get together, they end up firing a bunch of employees. That's sort of what happens when galaxies merge. Galaxies come together, and the stars don't like collide. When two galaxies merge, they sort of like orbit each other and form a bigger galaxy. And this is a basic part of how we got the galaxies we have today. The Milky Way, for example, we think is the product of the merger of several smaller galaxies, some bigger, some smaller. Sometimes you have like a big galaxy eats a small galaxy, sometimes two galaxies the same size. But when this happens, though the stars don't often collide, there are sometimes casualties because not all the stars then fall into a nice orbit around the combined mass of the two galaxies. Some of them just get kicked out. Well, I'm not sure nine year olds know about corporate burgers that much. You've got to prepare them starting early, man for the realities of the adult world. I think, what do you mean is like if I take a bunch of legos and nice mush them against another bunch of legos, some of the limbicgo pieces are going to fly out right away from the bunch of legos that I'm forming, yeah, right, And so almost all of the stars of the overwhelming majority of them, form some new galaxy, but some of them are lost. Remember, like a stable orbit is not always that easy to find. We think there are planets in our Solar system which we're lost because of crazy gravitational hijinks by Jupiter, for example. So it's much easier to lose something out of orbit than to gain something in orbit. So when two little galaxies come together to form a bigger galaxy, most of the stars end up happily orbiting the new combined galaxy, but some of them just get tossed out into space. Well, I think it's can definitely relate to that. It's much easier to lose their toys and to get new ones. And there's another process also where a galaxy can lose stars. Remember that at the heart of galaxies there's a huge black hole, this supermassive black hole, which can sometimes have the massive millions or billion times the mass of our Sun. It's really intense gravity, and we have these amazing movies of stars orbiting these black holes and going super fast. Well, sometimes those are stable orbits, but also sometimes they're not. So if a star comes near the supermassive black hole the heart of a galaxy, it can get whizzed around and then just tossed out of the galaxy sort of like a slingshot, right exactly the way like comets dive deep into the heart of our solar system, gain a lot of speed, and then get thrown back out to the outer solar system. In that case, it's still sometimes a stable orbit, but sometimes it's not. Sometimes we lose a commet, and could that happen to our son, to our start cod we somehow get booted off the Milky Way. It's possible the Sun is in a pretty stable orbit. We're not very close to the center of the Milky Way, We're not close to the outside. Every thirty one million years or so, we crossed the galactic plane. We sort of like go around in a circle that takes by two fifty million years. Then we also go like up and down relative to the plane and crossed through every thirty million years. So it's possible that our orbit around the galaxy could get perturbed if we come near some other star which like gives us a yank, and we end up like falling in towards the center of the galaxy and then getting shot out, or in if few billion years, the Milky Way and Andromeda will merge, and definitely some stars are going to get voted off the island, all right, So to answer Dirk's question, the answer is, yes, you can have stars that are not part of a galaxy, but they're most likely booted out. But I think it's pretty interesting to think that there are stars out there floating in the huge empty space between galaxies. I wonder if some of those stars could have planets orbiting around them, and maybe even life around them. Right, imagine being a life form looking out into the sky and one of these lonely stars. I bet the nice guy would look pretty differently than it does to us. Yeah, technically it's possible. Right. We don't really gain much benefit from being part of the galaxy. So if you took the Sun and you just deposited out in the middle of intergalactic space, our lives wouldn't really change that much. All we really need to survive is the Sun. But you're right, the night sky would look very different because all we would see would be galaxies. Right now, when you look up, you see mostly stars in the Milky Way, and a few little smudges from galaxies. So astronomers evolving on that star would think, Wow, the Earth is really weird because everything else up there is a galaxy instead of a star. That would be very puzzled. Right, this nice guy would just look black with smushes on it, right, exactly. And we know that there are a lot of them out there. Astronomers from Vanderbilt identified more than six hundred stars just past the edge of the Milky Way between Us and Andromeda. These are hypervelocity stars that we think we're ejected from the core of the Milky Way, and maybe there are planets around them, although you know, the intense gravitational push of getting whipped around the black hole might make a star lose its planets also, that would be a crazy ride. All right, Well, thank you Derek for that awesome question. And um, I hope you do make it into a team in the playground and not lose your toys. That's right, And if the Sun is injective from our galaxy, I hope we all go along for the ride. All right. Well, that answers all three of our listener questions. Thank you to everyone, especially Danica, Grace and Derek for sending us they're awesome questions and for being curious about the universe. And thank you to their parents for raising the next generation of science. This well, technically everyone's raising the next generation of scientists, because everybody's a scientist, right, That's right, exactly, So I'm just doing professionally. And thanks for everybody out there who encourages their kids to ask questions and wonder about the world and experience the joy of discovery and of confusion. We hope you enjoyed that. Thanks for joining us, see you next time. Thanks for listening, and remember that Daniel and Jorge explained the Universe is a production of I Heart Radio. For more podcast from my Heart Radio, visit the I heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows. Ye