Listener Questions 5

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Speaker 1: Hey, Daniel, do you get tired of answering questions? Oh? Never, I love our listener questions. I just mean questions in general, like about the universe, about your personal life, poor like this question you're asking me now from your podcast host partner. No, people ask me questions all the time, but it's fun to answer them. You know, sometimes I wish I got asked more science questions, you know, sometimes with questions are more prosaic. But about your kids? And your kids constantly pester you with science questions too, I wish they asked more. You know. It's the occasional like what does the black hole look like? But more often it's like can I have more dessert? Or how could my sister just to use the iPad more than I do? And the answer is always the same. Nobody knows that we have no idea. They're kind of six questions too, aren't they? Like? Um, they're about time? Who gets more time on the iPad? Or matter who gets more desserted? Exactly? And what about you? Your kids ask you science questions? Uh? They do, yeah, pretty pretty often. I think my kids, um like to read and sometimes they kind of make connections in their head and they ask me questions. And what do you do when they ask you questions if you don't know the answer. What do you mean you assume that I don't know the answers. I often don't know the answer, so I assume not everybody has all the answers. Sure, no, Well I do my best. I guess um and maybe baby. Mainly, I just tell them to send their questions into our podcast so that you can answer them. That sounds good. I'm glad to be your backup science parent. I mean, what's the whole point of befriending as physicists if not to get these questions answered? I knew, just would you want to be friends with the physicists? I knew? I felt used. Now I know why. Hi am Jorge. I'm a cartoonist and the creator of PhD Comics. Hi I'm Daniel. I'm a particle physicist and a backup science parent for many people out there. And welcome to our podcast, Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we take funny, weird, amazing, crazy things about the universe and explain them to you so that you can explain them to your kids or your parents or just sit them down with with our podcast as free babysitting. That's right. Yeah, so we we love answering questions, right Daniel. Oh yeah, it's really fun because we can think about the universe and we can talk about what's exciting for us. But the most is interesting is answering questions from listeners because it reveals what they understand and what they own't and what they're wondering about, what all those collective brains out there are cognating on. Yeah, so if you don't know this already, we actually answer people's questions. If we have an Instagram account, on Twitter account, on Facebook account, and if you post a question, well, first of all, follow us there, but if you post a question, most likely Daniel will answer the question, right Daniel, or at least maybe one of your regrets, that's right. No, I'll answer questions via email or Twitter or Facebook. I'll be honest, though, I don't use Instagram, so all those people asking physics questions on Instagram are just questioning into the void. Sorry, folks. The question is does anyone use Instagram anymore? Now that I don't, I think the question is who doesn't use Instagram these days? Just me, I guess, I guess just physicists, you know. But it's wonderful. We hear questions from all over the world, and sometimes there are questions people just had in their minds they wanted to know the answers to, and those are wonderful. But also sometimes the questions are in reaction to something we talked about on the show. You know, on the show, we do our best to think, what's confusing about this? How do we explain this? How do we make something clear? But we never can completely succeed. So it's really nice to have feedback when people say you said X, but then I that made me wonder why, and that helps us be more clear in the future. So please send us feedback, send us questions, send us presents, send us gags, send us whatever you have at Mostly you send us money please, I mean, how much do you think podcasting? Me? Podcaster? That's right? And sometimes people send us serious questions about the universe. And then sometimes people send us silly questions. Yeah, like what's been a silly question? All right, here's a question we got on Twitter from Patrick Nouman. He says, Dear Daniel and Jorge, I've got a question that really want to get answered. How heavy would a blob or banana bee of all of the photons in sun? And how big would it be? Oh? Interesting, So you took all the photons in the sun and somehow, what do you think, transformed them into a banana or put them in the space shaped them into a banana? What do you think I actually started trying to work on this question. At first, I thought, well, how many photons are in the sun, right, like, is that a number? Um? You know, and it's pretty tough. But it turns out you can do a rough calculation and the sun creates ten to the forty five photons per second. That's ten with that's a lot of photons, a lot of like trillion, billy busily but gillions, yes, exactly, billions and yeah, exactly. But not all those photons escape the sun. You know, the sun is a huge ball of plas and most of the stuff that's made by the Sun is then just reabsorbed by the Sun, and so only things that actually penetrate leave the Sun and hate your eyeballs arrive here on Earth. That's a tiny fraction what comes out of the Sun. But anyway, let's say you had ten to the forty five photons. Okay, that's a huge amount of energy um. And then this question is interesting. He said, how big would that be? Right? Like if you had a pile of tending the forty five photons, right? How well? How how how close together can you cram them in? Maybe? Yeah, And that's really interesting because there's no limit on how close you can cram photons together. That's not true ordinary matter like electrons and other particles. These things are fermions, and fermions are different from photons and other kind of particles that we call bosons because fermions have to have different quantum states. No two of them can be in the same quantum state. They can literally be on top of each other. That's impossible, that's right. They have to have some difference, like you can have two electrons in the same level of energy in a in an atom, but then they have different have to have different spins or something different about them, and so fer meons have to be distinguishable, whereas bosons, these are particles with integer spin like a photon. They can be right on top of each other. They can be exactly the same place, have the same momentum, had the same everything. I feel like the silly question is is gotten a little seriously Yeah, serious physics, yea, even silly questions reveals something interesting about the universe. And so you can have ten to the forty five photons on the head of a pin, basically right or on top of each other. You're saying, yes, exactly, all on top of each other in a tiny, tiny space. So thank you Patrick for sending in that hilarious question. It really made us think, and there really is some physics in that question, even in silly questions. Well, we do have three questions today from listeners, and so that is the topic of today's podcast. To be on the podcast, we'll be talking about listener questions five point five point one five point one because we because we just answered Patrick's questions, so we got to add a little that's right. We're part way through this episode already. Um, that's right. We'll be answering questions about electrons, about space, about stars, about black holes, questions from far away, and questions from surprisingly nearby. Yeah, and we might even know the answer to some of these questions this time, and if we don't, will speculate hilariously. All right, let's jump right into it. Daniel, there, Our first question today is from this really pretty cool guy, fun guy, one of maybe one of my favorite people, has a great dad. Yeah, so this is a question from Oliver from southern California. What if for whole solar system is in a black hole and we don't notice? Wow, that's a deep question. His voice sounds a little familiar to me. Yeah. What a what a smart sounding little kid. He sounds like he might grow up to be a cartoonist. Well not if he's that smart, hopefully. So yeah, that's my son who just asked that question in and he just turned to me one day, Well, what happened? What? He was reading our book? So we, Daniel and I wrote a book called We Have No Idea, A Guide to the Unknown Universe, available now in Amazon dot com. And and you can verify it's been read by at least one person since your son is reading it. That's right, that's right. He's under age, but he still counts as a person. He's nine years old, and so he's been reading our book and I always kind of wonder how much of it he's getting. You know, he's nine, he's in third grade. Um, but he seems to be enjoying it, and he keeps reading it, and so one day he just turned to me and he asked me this question, right, and what do you think is behind the question? What do you think he's wondering? Explain the question to me? Even explain my son do a deep dive. If I knew that answer, Daniel, if I could explain my son, my parenting experience would be so much. You know, I thought it was really interesting. One part of his question says, what if our whole solar system is in a black hole? Cool? Fascinating, Yeah, But then he says, and we don't don't even notice? Like I think that taps into you know, is the universe different from how we expected? Is it possible that we think we're living in universe X, but we're actually living in universe? Why? You know? I think he was probably kind of reading about black holes and he just kind of wondered, like, what what if? What if we're inside of a black hole? Is that possible? Like could the universe? Or or like could could a solar system exists inside of a black hole? And you know we don't even know it? Yeah, And I think there's something wonderful there about the feeling that maybe, you know, the universe could be revealed to be totally different from what you expected, because that's precisely happened a lot of times in history, right, we thought, oh, the universe works this way. Nope, it's totally different from what you imagined. And those are the best moments in physics. So to hear your son like sort of wondering if he's coming to that realization him self, or wondering if this kind of realization is around the corner, that's fantastic. He's been bitten by the physics bug, so be careful. Oh no, he's gonna be like Spider Man. Well that's only if he's bitten by a radioactive physicist. Okay, radioactive. Well I grew up in Los Alamos, so maybe I'm especially radioactive. But I'll do my best not to not to about your son. Yeah, but let's break it down. Um, it's interesting question. And you know, something that's important to think about is sort of the size of a black hole, like, could our entire solar system fit into a black hole? Well? Right, the size of a black hole is really we can usually consider that to be the size of the event horizon that's the point, right, the black style. Yeah, like the point return. Look at a black hole, it would look like a black sort of sphere, and so the size of that sphere, that's the size of the black yeah. Yeah, And if you go past that point, you can't escape, right. And nobody knows what's inside of a black hole, but we know how to calculate the size of the horizon. It's determined just by the amount of stuff in the black hole. So the more mass in the black hole, the stronger the gravitational pull. The farther away it can grab stuff and never let go, right, So the size of the black hole is determined by its mass. So how much stuff is in our solar system? Well, basically the first approximation our solar system is just a soun. Like the rest of the stuff in the solar system Jupiter, Mars, me you hamsters, all that stuff is negligible. It's a tiny fraction of the mass of the solar system. So basically you can ask, like, if you had a black hole with the mass of our Sun, how far away would the event horizon B would it be out past the edge of the black of the solar system? Is it possible to fit a solar system in a black hole that has the mass of our Sun. It's sort of the way I interpret the question. So you're interpreting the question as could our solar system be a black hole? Yeah? Exactly? Could we be inside a black hole right now? Is there enough room in a black hole with the mass of the Sun to fit the entire solar system? So could we be in a hole where the only thing inside of it is our solar system? Yeah? Exactly exactly is how you're interrupting the question. And the answer to that is no, Because a black hole that has only the mass of our sun, the event horizon would only be three kilometers from the center of the Sun, and so that definitely wouldn't be big enough to have the whole solar system in it, because the solar system is a lot more than three kilometers. It's one billion kilometers wide. So we couldn't be in a black hole where the only thing in it was our solar system. But is it possible that we are that our solar system is inside of somebody else's black hole? You know what I mean? Like, maybe there's a black hole out there with a lot of mass inside of it and we are just inside of the event horizon of that black hole floating around. Yeah, that's possible. Right, Let's let's consider that for a moment. So, what if there's a really ends blobs somewhere else sort of nearby, and that makes a black hole that's big enough to encompass us, and we're inside that black hole right right right, Well that's possible, but it's difficult to imagine because such a huge mass would have a big effect on us. You know, if there was a like if there's a really big mass somewhere else inside our Solar system next to the Sun, like an invisible huge blob of dark matter, that that made their enough mass so that the black hole was big enough, we would definitely notice that that would affect the orbit of the planets. What if there was another big mass kind of far away but close enough that we were still inside the event horizon, Well, you're talking about still really strong gravity. So it's hard to imagine having some enormously powerful gravitational attractor nearby and not having it disturbed like the orbits of the planets or even just tossing of baseballs and all sorts of stuff. So I think if you were inside a black hole that was big enough to hold a solar system, it would have to have a huge mass, and that mass would definitely be noticeable. It would affect the way things move on Earth, would it, though, Because you know, like um so so our our solar system is moving around a galaxy, right, Like, a galaxy has a lot of mass and um and it's huge, and there's a lot there's a huge black hole in the center of the galaxy, but it's not really affecting us in a local level, right, Like that gravity is kind of spinning us around the galaxy, but it's not really changing the orbits of the planets around the Sun, that's right. Yeah, And that black hole in the center of the galaxy is really massive and it's pretty big, but it's also super duper duper duper far away. Right. Any black hole that's either near enough to include us or far away but huge enough to include us still would definitely affect the gravitational poll But you know, I haven't done the calculation. There is one configuration I imagine though. Imagine our entire solar system and then it's surrounded by some enormously dense sphere of material. Okay, if you're inside a sphere of material, then the gravitational pull of that stuff doesn't affect you at all, right, because it all balances out. Is enough stuff on the left to balance the stuff on the right. Just like that episode we talked about where you jump inside the Earth. Once you get to the center of the Earth, is no gravitational force from the stuff around you. Right, Well, if you have to spear a super dense material surrounding the Solar System, right, then that might be enough to create a black hole, right that we would be inside of. We wouldn't feel the gravitational force because we would be inside all the stuff. It would be all around us. Yeah, that's what I mean. Yeah, yeah, but they have to be perfectly distributed, right. And the only reason that there's one reason to think that's not the case, and that's that we have sent stuff outside the Solar System, Like we launched probes and they're floating off into space and we're watching them and they haven't like banged up and the wall of some hugely massive blob of stuff. But what have you expand that idea even further to encompass the whole observable universe. It is possible then that we could be inside of a black hole. Yeah, yeah, it's possible the entire observable universe is inside a black hole. Yes, you can't rule that out. How do you feel about saying that on a public record, Um, I wonder if any of my colleagues are listening. No, I think it's awesome. You would be surprised. I think it's awesome, And I think sometimes these awesome questions come from the minds of children, And that's why I hope that people are listening to the podcast with their kids, because kids ask amazing questions that make us think about things we otherwise would have totally discarded that might actually be reality. Well, so that's so that's the answer. The answer is that it is totally possible that we are inside of a black hole and not knowing. Yeah, but I think our whole universe would have to be inside the black hole, not just the solar system. But yeah, that's a pretty small conviat for it for a yes answer to that question, isn't that sort of a theory out there that were like the whole universe are are inside the whole universe inside of a black hole, and there are other black holes and stuff. Like that or is that pretty fringe? I think it is the theory out there, and it's pretty fringe, But it's also totally possible, you know, like we really just we don't know what's going on inside black holes? Are there little universes in there? You know? The inside of a black hole is totally disconnected from the space that we live in, right, Like there's no way to get from here to there, right, That's why that's how a black hole works, even like can't escape it, not because it's like slowing down the light as it tries to leave, but because it's bent space in such a way that there's just no path out, like just zooming around inside the black hole. So in some ways you can think of it as sort of like a different universe disconnected from our our space, and so you can imagine then anything that goes on in there. And uh, when experiments can't constrain things, theorists minds tend to go wild, and so they think about all sorts of crazy stuff that could be inside there, insing bears or entire universes. Crazy scientists and nine year old boys whom I grew up to be crazy scientists. All right, Well, that's the answered for Oliver's son of Jorge, and I'll let him know if he has a good sum he stumped the physicists. Yeah, it's a great question. If he was Icelandic, his last name would be or Hasten exactly. All right, Well, we have two other awesome questions that we are going to answer about electron identity. I guess is that is that we would be the right topic and also about dark Matter stars, which sounds like a heavy battle band last science fiction movie. So stay tuned, will be right back. Al Right, we are back answering list are questions, and so our next question comes from Yugi from the Netherlands, and he is wondering if electrons have identity crises. That's right, And this particular listener is something of a super fan, writing to us on Twitter fairly often with insightful questions, and he sent me this one and I thought, well that's a good question, let's take it online, and so here he is, Hi, Danielle and Jorge. My name is Eugene Raudemake and I live in the Netherlands, hence the actions. I'm a big fan of your morphous poticast cities, for it makes me understand more of physics, and it makes me think a lot about the universe in general. After listening to your episode about quantum tunneling, the following question came to my mind. If an electron tapt well say A, suddenly appears in well B, how can physically still it's actually this very same electron. I realized that I had the both bowl empty swimming pool and the analogy in my mind when the Christians sue appearance in my will. Thanks for spending time answering my questions, all right, thank you for saying this question, and also for being a fan of the show. We really appreciate everyone listening out there. Yeah, exactly, And uh, it's really a wonderful question, you know. To me, it goes to the heart of like what are these particles? What are we talking about? Um? But the way I interpret his question is like, you haven't quite an electron over here, and physics tells us the electron can then later be over there. But his question is, how do you know it's the same electron? Right, because we don't have this sort of notion anymore of a classical path that you can like watch a baseball fly through the air and when a baseball, you know, when somebody hits a home run, you watch it fly. You don't ask like, is that the same baseball or is it suddenly swapped out? But with quantum mechanical particles, because you can't observe them all the way along the path, you just get these snapshots. You can sort of wonder like, how do you know that's the same electron? Maybe it's from another electron down the street, right, it's just Tom or Harry or Mary or Sally. I feel like the question is there such a thing as an electron? Is there an electron? You can say and follow it around and it has a birth in a you know, journey, and then it maybe answer at some point we can you follow an electron? Or are we getting into identity politics now? So there's electrons go back to where they came from physics. Yeah, obviously we're not qualified to dive into those topics. You know, well that's a it's a famous topic in physics, and it's something that real physicists wonder and uh. In this famous physicist, John Wheeler, he had this sort of moment of insight and I don't know if he was smoking banana peels or what. But he was wondering, like, why do all electrons behave the same way? Like you drop an electron in the in the circumstance, it's always going to get repulsed in the same way. It's not like this one's got a little bit more charge and that one's got a little bit more mass. They're all identical. They're not like scoops of ice cream, right, they all have exactly the same properties. And he had this moment of in said he thought, wait a second, maybe there is just one electron. These are all the same electron. What what do you mean, like the electrons in my body and the ones in your body, they're all the same. Yes, yes, sort of um, And I think I think that's actually sort of the answer is that the electron is not really um a particle that has an identity. It's sort of like a state of mind or a state of matter, right, because these days we don't think quantum mechanically about particles as the fundamental basis of the universe. Instead we think of fields, right, and particles are just excited states of the field. It's sort of like when you look at the ocean, you know, and you've tried to follow a wave. Right, A wave is not the basic unit of the ocean. It's the water. Right. The wave is just like, you know, the ocean has got excited a little bit by the wind, and it comes and it goes, and there's more waves behind it. It's just it's just the motion of the ocean. And that's right exactly. And so in that same way, you can think of electrons. Not a's like, here's a little chunk of matter, a little like piece of the universe we're gonna follow around. But it's just like a momentary excitation of this sort of hard to think about thing called the electron field which fills the universe. And when it gets a little bit of energy somewhere, you call that an electron. It's not an object. It's kind of a wiggle of an object. Yes, exactly, it's a wiggle of an object. And you know, this goes back to that other question we tried to answer. It's a photon, a particle, or a wave, for example, And I think I said on that podcast that it's sort of neither and sort of both, and really it's something else weird and fundamental that we just cannot understand by making analogies, right, analogies from our macroscopic experience. Things that we're familiar with just don't work because we've never seen anything like that before. Well, it turns out you can apply the same idea as to an electron also, right, an electron is both a particle and a wave and both and neither and something else totally weird. It's really just the excitation of a quantum field. And and the reason, the reason actually that we came up with quantum fields, the reason that this whole development is progress, right and not just confusion, is that it helps us think about the way particles are created and destroyed. Because when electron is flying through um the universe, it doesn't just sit around happily. It generates photons, and those photons turned into electrons and positrons which turned back into photons. Every electron is actually surrounded by like a fuzz ball of virtual particles, photons and electrons and things popping in out of the vacuum. What do you mean, like an electron is not always an electron. It's constantly kind of fuzzy and morphing and changing. Yes, exactly, it's constantly morphing and changing and it's surrounded by a ball of like almost an infinite number of low energy particles that are being created and destroyed around it. Right, And so we came up with this alternative mathematical formulation quantum field theory, because it's really hard to follow the path of an individual particle through this sort of probabilistic storm of things that's happening, and it's much easier to just think about the field that's generating all these particles. And then a particle creation and destruction is much more natural in quantum field theory than an old quantum mechanics where we try to track follow an individual particle as if it was a baseball. So we have to sort of let go of this whole idea of particles having identities, particles having paths, um and just think of them as momentary oscillations in this field. Well, I think there's several questions here, like, you know, maybe maybe you he was also thinking of the wave analogy maybe, and so maybe his question was, you know, just like you can follow a wave in the ocean, you know, if you if I make a ripple in the in the lake or something, or you've even wave is made out into the ocean. You can you can kind of follow that wave, right, like, that's wave A. I'm gonna call it Sally, and you can follow Sally as it moves across the Pacific, right, you sort of can. But what if Sally looks exactly like all the other waves, and there's billions of them, and you look away, and then you look back and you wonder which of those waves is Sally. That's the situation where the one that um like, if I see it at point A and I see at point B one second later, well that's his question, right, the one that's a point C another second later, basically right, could be or could be there along the way got turned into something else and then got turned back into a wave, And is it the same wave then? But it almost always is, isn't it? Like? Do electrons really just transformed to something else constantly when we're not looking, constantly, even while we're looking, electrons are constantly influx Yes, exactly. You know there's that even the ones that in my body, even the ones in your body, they're not special, sorry to inform you. Um, you know, there's that ancient philosophical question, right, there's some some ancient Greek ship, and every time it comes into harbor that it's lost a piece and they repair it, and then after five years there are no pieces of the original ship, and they wonder, like, is it still that same ship? You know, if it's made out of all new pieces? Um, And it's sort of that question, but it's the particle version of that question. And uh, wait, what if it rides the same wave though that the Greeks mine? Yeah, exactly, And so I'd say in this in the same way, there there is really no particle identity. Um, I don't I don't know that I've smoked enough. But An appeals to say they're all the same electron But I think sort of what he's saying is that they're all manifestations of the same field. Right, there's really just one electron field and it appears and lots of different places is in the universe. But then what's really going on? Because you know, I feel pretty consistent, you know, like I am this way sort of now and and I'm sort of the same way a second ago. I think that's my perception. Are you saying that, you know I could have changed into something totally different between now and the next second, that I am conscious about, yes, But the jorhan nous is not about the stuff that you're made up of, but the arrangement of those particles. Right, just like that ship is not about the pieces of wood that went into it, but how they're put together and what it's doing, and you know how it spends its time. And so in the same way, you are a constantly frothing mass of quantum mechanical particles. But that's not what makes you you. What makes you use the way they're arranged and the way they live their life. Well, I am a constant frothing mass of something. Sure, it's a really hard question. And you know, this is a question which is definitely on the philosophy side of the threshold. And something I love about physics is that it bumps up against philosophy so often because they're deep consequences to the answers of physics questions. And so I've always been really interested in in the philosophical implications of particle physics. Um, but I have to say it's not something that most of us, most of us particle physicists, are actually qualified to talk about, even though we do pontificate long windedly on it. Oh, I see. It's it's one of these questions that the answer is kind of like it depends on what the definition of is isuly I have to go there, but I think it applies in this case. Yeah right, It's sort of like it depends on what you mean by having an identity or being the same electron exactly, you can dig into that forever and smoke manin appeals and not necessarily make any progress exactly. Yeah, or cigars. But it's a really fun question, So thank you for asking it. Yeah, well, what's the What would you say is the answer? Then? Do electrons have an identity or can you have the same electro on? The answer seems to be I would say no. I would say identity is a macroscopic quality that we like to attribute to things because we're used to it, because we're familiar with it. We expected to tom. We expect also tiny particles to have it, but they don't and and so I think it's odd and uh, and it's it tells us more about how we think than about how the universe works. So you're saying, at the microscopic level, at the individual electron level, these things we can apply because things are just constantly changing and frothing, and yeah, exactly, I don't think it has any meaning at the microscopic level. All right, well, thank you hear you from the Netherlands for that question. Please keep listening. I hope he answered your question. Answer your question to your satisfaction. Uh So we have one more question, and this one comes from Mexico or Mexico about dark matter stars. But first let's take a quick break. Al right. Our last question of today comes from ben who is sending his question from Mexico, and he has a question about dark matter stars. Hi, Daniel lane J. This is Benjamin from Mexico, and I was wondering, if the dark matter has all these gravitational properties as the regular matter, why have an astrophysicists discovered yet a big celestial body made of dark matter, like a dark matter star or something big that we can indirectly now it's there. Thank you. All right, that's a pretty cool question. Where aren't there dark stars besides a in comic books? I think that's a comic book villain. Exactly it should be, yeah, exactly. Um No, it's an awesome question, and the way I interpret it is that he's wondering why can't we tell that dark matter is there? Why it hasn't dark matter coalesced into some sort of object that we could then pinpoint, Because I think he maybe is frustrated at the sort of diffusiveness of dark matter. We know it's there, we know it's sort of everywhere, but we can't seem to say exactly where it is and why not? Is that how you interpret the question? Why does it stay so fuzzy? Yeah? Yeah, exactly. And I think that the key thing to understand here is remember that gravity is really really weak, and it's the only way we can see dark matter so far. The only way we can feel it is through its gravity, and and so it takes a huge amount of stuff to notice something just from gravity. Remember, the gravity is so weak that you can feel the Earth's gravity, but you can't feel the gravity of your car or your house, even though there is a gravitational pull there, it takes some huge body to even feel it. Right, Well, maybe we should recap and a little bit about dark matter. Right, So we know that dark matter feels gravity, right, that's how we sort of know it's there because it's pulling us around the galaxy. But it doesn't feel electromagnetic forces, which means we can't see it or touch it. Right, that's right exactly. It doesn't give off light, it doesn't reflect light. We can't see it using any of those normal methods that we usually used to see stuff, right, But it does feel gravity, and so I think maybe Ben's question is, if dark matter feels gravity, why hasn't it clumped together out in space because it's attracted to itself, right, isn't it attracted to itself? Dark matter is attracted to itself by gravity, absolutely yes, and it has clumped together. Right, dark matter is not evenly spread throughout the universe. Dark matter has clumped together thanks to gravity, and it's formed these big blobs. And it's, in fact only because dark matter has clumped together to make these blobs that we have galaxies and we are alive, because without dark matters gravitational pull, there wouldn't be enough gravity to hold the galaxies together. And we've done simulations and seeing that in universities without dark matter, it takes a lot longer for gravity to pull all this luminous stuff together to make stars and planets and galaxies. So dark matter does make um structure, It does make objects. But those objects are sort of big and diffuse, and and they're sort of the size of the galaxy. And and you might ask, well, how do we know that the dark matter inside the galaxy hasn't also clumped together to make you know, star size stuff or planet sized stuff the way normal matter has, right, And And we don't know the answer to that, right, And the reason we don't know is because we can't see dark matter and enough to tail Like, it's totally possible that the distribution of dark matter in the galaxy is either a totally smoothly spread out right, be sort of like a cloud. Now we know it's denser towards the center and less dense towards the outside, but it could still be like a like a big cloud, right, Or it could be that their structure that it's clumped together to make, you know, a bunch of dense points, just the way normal matter has. So there could be dark matter stars or dark matter planets exactly, but the only way to see them would be through gravity. And it's really hard to see a gravity from like one planet or the gravity from one star, right unless it's really close by. Like if there were dark matter stars and a dark matter star passed near our solar system, then we could detect it the way we detect black holes right there. Black holes are invisible. We detect them from their gravity. Sometimes we detect black holes because of the X rays that are produced from compressed gas nearby. But a lot of black holes we see through their gravity. But you need to be a pretty big black hole to detect its gravity from far away or to see its gravitational effect. Are nearby stuff, right, And in fact, there are a few of these things we found, and they have a pretty silly name. You ready for it always physics really names. Yeah, they're back a long time ago before we knew whether dark matter was the thing. People were wondering if they were just big clumps of normal matter there was sort of hidden out there, and they gave them this name, massive compact halo objects, and the acronym for that is m A C h O. Right, so mach of these not nachos. Nachos are a totally different thing. These are MACHOs. And so that's not physicists over compensating for anything, not at all. No, And so people went out there and looking for these things, like can we find dark blobs out there, dark condensed blobs out there that might be responsible for all the missing mass, right, And they did find a bunch of not nearly enough to account for all the dark matter, but they found a bunch of them. They would find them like eclipsing stars or bending the path of other objects. Um. And so we know that there are dark objects out there. Some of them could be dark matter, right, Some of them could be so totally possible that dark matter has clumped these objects together. We just don't have the gravitational sensitivity to see them because they're too small. Essentially, in gravity is so weak, Like our ability to notice or feel or see dark matter is not at the planet or at the star level. It's only at sort of the galaxy level, yeah, exactly a little bit less than the galaxy. We can we can get some sense of where they are based on how rotations vary as a function of the radius from the center of the galaxy. But roughly yet much more the galaxy level than the star level. But but it's fun to think about, like imagine what would happen. What would happen if you had a huge blob of dark matter and it coalesced into sort of a tight blob, like would it make a star like planet? You know? And we when we say a star, we sort of mean something that's big enough, has enough gravity that it's pushed the stuff together that begins to fuse and release energy, right, And so another interesting question is like, what would happen if you squeeze that much dark matter together? What interesting things happen, like, um, you know, elements fusing and releasing photons and things like that. Well, we don't know, but we know it's not made of elements, right, It's not made of atoms. It's made of some some other kind of matter. And the only interaction we know it has is gravity. So as far as we know, it would just squeeze and squeeze and squeeze and squeeze, and there's no repulsion. Right. The thing that keeps a star or a planet from immediately becoming a black hole are the other forces. It feels like electromagnetism, which and the strong force which fuel fusion, right, which keeps a star exploding. It keeps it from collapsing immediately. So if dark matter has no other forces, then every time it gets to be a pretty dense clump is just going to turn into a dark matter black hole, because that's it's just gravity. But if dark matter does feel some other force, maybe some new force we've never seen before that only affects dark matter on dark matter interactions, then maybe, you know, clumping a bunch of the dark matter together could sp some sort of dark matter interaction which could release like dark photons. We're just wildly speculating here because we just really don't know what happens when dark matter bumps into dark matter, dark photons, and dark light. Yes, exactly, sounds like all good comic book characters. That's right. Today we've been exploring the connection between physics, philosophy and physics and comics books. Is it trifecta um? I think? You know, maybe that's where Ben's question came from. You know, like, you know, we know dark matter feels gravity, so why hasn't it clumped into dark matter black holes? You know, why is it still kind of diffused and and not um not more noticeable? You know? Does that mean that you know he's a alternative you mentioned are maybe probably true? You know that there are other forces or there are maybe other mechanisms going on inside of a dark matter Absolutely, I think a lot of physicists believe that there must be some other kind of force that dark matter feels, not just gravity, and the sort of complicated arguments for that based on what happened in the early universe and how some matter and dark matter turned back and forth into itself. We have indirect evidence of that happening, which suggests there must be some other force that dark matter feels, but we haven't figured that out yet at all. It's really it's very indirect arguments. But there is one thing that keeps dark matter from collapsing sort of quickly into a black hole, and that's our old friend rotation. Like, one thing that keeps the galaxy from collapsing into a black hole is that it's spinning, and so that keeps the stars from falling in just the way spinning the Earth spinning around the Sun keeps it from falling into the Sun. Right, it's an orbit. If you have a huge blob of dark matter and it's rotating, that rotation keeps it from collapsing gravitationally into a black hole. And so that's something that dark matter can do, even if even if it has no other interactions. But yeah, I think that it's totally possible that dark matter has formed really dense blobs inside our galaxy, and it's possible that there's new interactions doing weird stuff inside those dark matter objects that we have no idea about. But I think what you're saying maybe is that we we sort of haven't seen that yet, right, Like, if if we are surrounded by dark matter stars or dark matter you know, giant asteroids, you know, and one of them came through our Solar system, would we would notice it? Right, like we would notice all the other planets going whoa gravitation, Yes, exactly, that's the kind of thing we would notice for sure. I mean we noticed Omuamua, right, this tiny little rock coming through from from deep space and passing through our soul system with no gravitational interaction at all. That was but it was reflective. But imagine some really dense, heavy object that perturbed the path of the planets that we would definitely notice. Yeah, it would have to be pretty big though, because gravity is pretty weak, So like some random rock flying through the universe we wouldn't notice and have to be you know, like, it had to be a pretty significant objects. I'm not sure exactly how man, but some significant fraction in the mass of the Sun at the very least. Yeah, we would notice it, right, It would totally disrupt our solar system. Yeah, absolutely. But there could be a lot of these dark matter blobs out there and just none of them have passed through the Solar system because the galaxy is huge, right, and there's lots of blobs out there that that made a normal matter that don't pass through our solar system. Doesn't mean they're not out there. I mean, there could be a giant banana shaped massive dark matter out there that's waiting for us to slip on. That's right. You're gonna tie all the questions together. What if there's a banana shaped massive dark matter creating a Solar system sized black hole and we're in it, could we tell if there was another one that was identical? All right? Well, I guess that band's answer is that there could be dark matter stars and planets or things out there. We just we just can't see them yet. That's just don't have the the right glasses to see it more sharply, right, that's right. Yeah, um, And it's not clear that we ever will because we don't know what glasses to put on, or if there are glasses that you could even potentially theoretically put on to see this stuff. Well, obviously we just need dark glasses. I wear my sunglasses at night. I don't know about you. All right, Well, once again, thank you listeners for sending you as your questions. We love to interact with you online, and so please follow us and please tell your friends about this podcast. That's right. And if you're listening to us talk about something in physics and you have a question that pops into your mind, please share it with us. The reason we're doing this podcast is to clarify these things and explain them to you. And so there's something we've missed, we want to get on it. Yeah, and we'll answer it even if you are not our sons, unless you're on Instagram. In that case, sorry, in that case, you're out of luck. Do you have any sons on Instagram? You not aware of your trendy and like the rest of the universe, then maybe you should ask the question on Twitter. That's solid advice. Thanks for listening, hope you enjoyed it, Thanks for tuning in. If you still have a question after listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge That's one Word, or email us at Feedback at Daniel and Jorge dot com. Thanks for listening, and remember that Daniel and Jorge Explain 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. Yea