Daniel and Kelly’s Extraordinary Universe - Are black holes really black holes?

Episode Date: October 21, 2021

Daniel and Jorge explore the question of whether black holes are actually "dark stars" Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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We'd love to have them on the podcast. What do you mean? What else could it be? Well, what do you really know about an electron? Well, that's a good question. And you can measure things about it, like it's mass and it's charge and it's spin. So even if you can, you know, look at it directly, that's enough to tell you that it's an electron. I guess so.

I mean, if it quacks like an electron and it walks like an electron, then you call it an electron. A ducktron, maybe. But I guess, you know, how do you know there isn't another particle with like the same charge and mass and spin but is not an electron? Oh, like another particle hiding in electron clothing? Yeah, like the incognitone or the faux electron or the non-electron or the electron knot. Well, I'm glad we have a name for it, even if we haven't discovered it yet. Hi, I'm Horam, a cartoonist and the creator of PhD comics. Hi, I'm Daniel. I'm a particle physicist, or at least I walk like one, and I quack like one.

Oh, really? Physicist is quack? Is that a thing you do when you discover something amazing about the universe? Oh, yeah, we quack about quarks all the time and quasars. Yeah, I guess regular nerds snort when they laugh and get excited. Physicists are hardcore and you quack. Yeah, exactly. Don't quibble about the way we quack. And that's why you fly south every winter, right? That's why I live in Southern California. sabbaticals in the South Pacific?

No, I made a mistake. I took my sabbatical by going north. I went to Copenhagen briefly. Oh, but you went in the summer, though, right? I did. So the days were long, right? Exactly. It's the right place to go in the summer.

This is one smart duck. But anyways, welcome to our podcast, Daniel and Jorge, Explain the Universe, a production of I-Hard Radio. In which we fly north and we fly south. We go on sabbatical and we engage our brains in the big questions of the universe. We try to ask the biggest, deepest, darkest, craziest questions. about the nature of the universe, what's in it, what's out there, and what it really means. Is the reality we see around us, the reality that's actually out there independent of human

thought, or is it vastly different than our crazy, tiny human brains can't imagine? Is the world lying to us and hiding and pretending to be something that it isn't, or is it just the way it looks? Yeah, because it is a pretty tricky universe, you know, it's not only big and almost hidden from us because it's so large, but there's also, you know, kind of strange things about it because, you know, the only things that we know about the universe are the things we can see, or at least measure with our instruments, and sometimes, you know, the universe plays tricks on us.

Yeah, and you can ask really fun, interesting philosophical questions, like, how do you know what something is? Like, you eat an ice cream cone? You know, it feels like an ice cream cone in your hand. It tastes like an ice cream cone. How do you know it's not actually something else and you're being fooled and that it tastes like an ice cream cone, but it's actually something crazy and weird, like an assembly of nanobots that's been collected to, like, you know, you know, it's not.

invade your body and taste like ice cream. Oh my gosh. You just gave me nightmares about eating ice cream. I hope I didn't just ruin ice cream for everybody. You might have. Yeah, now I'm going to worry about eating nanobots or something. Evil nanobots, fooling my tongue. There is a deep question there because we are limited in the ways that we interact with the universe, right?

We can't see the absolute ultimate, complete truth of the universe ever. We have these narrow little ways. We can see, we can taste, we can touch, we can smell. and that paints a picture in our minds of what we think the universe is like, but it's a very narrow way to interact with the universe. And it is possible that we are confused about what's actually out there. Yeah, because I guess the universe is tricky like that. And I mean, it's so complex that something that might seem like, you know,

ice cream could be something else. You know, it could have fake sugar or nanobots. Yeah, exactly. Or artificial flavors, you know. Or artificial nanobots. Like, hey, I ordered nanobots of my ice cream. These aren't real nanobots. Now I can't even trust the nanobots.

They could be, you know, the cheap kind or something. That's right. They kind to give you indigestion later. You don't want to eat those. They could be picobots or femtobots. Who knows? Well, I paid for nanobots and I just got these millibots. Man, I can even see these with my eyeballs.

What's going on? They're too crunchy. Yeah. They ruin the texture of your fake ice cream. But mostly we're not that worried about ice cream. As long as it tastes good, it's fine. Mostly we're worried about the nature of the universe and what's in it. What's out there in the universe?

Yeah. And one of the most interesting things out there for people to study are black holes. It seems like we get a question about black holes almost every week on the podcast, right? Yeah, this should basically become a black hole podcast. We're basically just falling into the gravitational attraction of the mysteries of black holes. Yeah, I guess they are very attractive and deep. Yeah, and once you start talking about them, you basically can't escape. There's like a question horizon or something.

Yeah, it's a massive topic. But even black holes as, you know, as much as we know about them, like we know they're there, you can see them gravitationally. And now recently in the last year or two, we've actually gotten pictures of black holes, right? Yeah, we have a lot of information about black holes. And you just said, we know that they are there. And that's a really interesting question. Like, we know a lot of things about black holes. We've measured a lot of things about black holes.

A lot of things that we see make sense if black holes were there. But, you know, how do we really know? it's not just a bunch of nanobots out there fooling us in deep space. Oh, man. I imagine we're not going to be licking the black holes or eating them. Hopefully not. I don't think anybody ever said licking the black hole until you just said it. I think that's the first time in human history, anybody ever said that.

We'll trade that and put it on our T-shirts. Daniel and Horace explain the universe. Licking the black holes. That's like a pitch for the science fiction version of a Christmas story. Yeah. You're going to shoot your eye out and or fall into a sense. singularity forever. That's right. All right. We're talking about black holes today and this sort of philosophical question almost about the true nature of black holes and whether or not

we are actually looking at or feeling black holes. Yeah. What's actually out there that's giving us the impression that black holes exist and could it be something else masquerading as a black hole? Oh man. Sneaky. So today on the program we'll be tackling the question. Why does black holes are not actually black holes? And Daniel, are we questioning, you know, that they're not actually black, the color black, or that they're not actually holes? Or both. Both and everything. We're questioning everything today.

We're blowing it all up. No, we are wondering what we actually know about the nature of black holes. What evidence do we have that they are this weird conceptual object that really just exists in our minds and existed only in the minds of physicists for 50 years before we discussed. them. Well, actually, I guess maybe they existed in the universe before that, but the idea is only 50 or so years old. And so we're asking the question is what's actually out there consistent with what's in our mind. Yeah, because I think black holes have had sort of an interesting journey, right? Like, first we thought up of them as an imaginary thing. Like, we saw the theory and we imagined that they could exist. And then we sort of confirmed that they're

there, but not actually seeing them. They sort of looked like they were there gravitationally. And then more recently, we've actually seen them. We have pictures of them. But now we're asking the question here today, are they really actually black holes, the things that we're seeing and feeling? Yeah, because can you really see something that's just black? You know, it's like sort of not seeing it is seeing it.

You know, we didn't see light from the black hole, which would have told us it's not a black hole. What we saw is not light, which is not the same thing as seeing the black hole. We didn't see the not black hole. or we saw the not black hole. We didn't, I don't know, I'm confusing myself here. I didn't not see a not black hole that is not actually there.

Let's just keep going, yeah. Exactly. Consistent with the black hole prediction, we didn't see photons from it. What does that actually prove, right? Right. If it looks like a triple negative and it walks like a triple negative, it's actually true, maybe? I don't know. These philosophical jokes are too much for me.

But I guess if a black hole is not actually a black hole, what else could it be? Yeah, and so there are a bunch of other. ideas for what could maybe be masquerading as a black hole, what out there in the universe, other theoretical concepts, for what could give us the same sort of set of observed data that could give us the same experience without actually being a black hole. Interesting. Do we have a name for these mysterious fake faux black holes or black holes? We do.

And physicists call these things dark stars, which sounds sort of cool in science fictiony. It does sound like another Marvel superhero or villain? I think actually that is maybe a DC hero, I'm thinking. We'll have to Google it. It sounds to me like the jet black version of the Death Star. Interesting. That's for the next Star Wars sequel when there's another Death Star, like the fourth one, but actually bigger and darker?

Was that what you're saying? Yeah, well, you know, in Star Wars, they're always saying, that's not a moon, that's a space station. And this one, they'll say, that's not a black hole. That's a dark star, space station. Oh, my gosh. Call J.J. Abrams. I'm sure he's a listener.

So, JJ, you call us. Yeah, that's right. You have Daniel's email for waiting. So a dark star. So that's kind of what we'll be talking about today is that, you know, maybe black holes are not black holes. Maybe there's something called a dark stars. Yeah, exactly.

These are fun, crazy concepts that might be real out there in the universe. So as usual, we were wondering how many people out there had thought about the trueness of black holes and had heard of these things called dark stars. So Daniel went out there and asked people on the internet, what is a dark star? And if you are out there in the internet and still don't feel safe venturing outside

and talking to humans in person, I get it. And so if you'd like to participate in these questions online, please don't be shy. Write to us to questions at Danielanhorpe.com. We'd love to hear your voice on the podcast. So think about it for a second. If I say the words dark star, what comes to your mind?

It was what people had to say. I think a dark star is a white dwarf that has sufficiently cooled to become a black dwarf and doesn't emit any radiation. Sounds like it's one that would not emit any light, but maybe it still emits radiation. Why that would be, I have no idea, but that's my guess. So I think I've heard of this where, like, say a brown dwarf, a brown dwarf, a brown dwarf. is technically a star, but it's a lot dimmer and a lot cooler and typically a lot smaller. So that would be what I would think a dark star is. White dwarfs are going to burn out and become dark.

It could also be you guys thinking about dark matter somehow forming a star, but the dark matter cannot interact with itself, so does that work? At the beginning, I thought this dark star was a black hole, but lately I read that dark star might be a type of star from the beginning of the universe, a really, really big star, much bigger than Biddlejuice or any other type of star that we've seen until now. So this is from the really beginning of the universe. If I say to you, what is a dark star? What would you think? Well, probably it could also mean a not very bright star. And mostly there are redwarf like Barnel Star or Proxima Centauri.

Are those dark? Not very dark, that's not very brights. Oh, okay. A dark star. Also awesome name for a band or opening cover of a band. dark star. Definitely, I'm going to go with the dark matter star. Even though, dude, I have no idea how such a thing could exist, because what even is dark matter, no one knows. But if you could clump and emit energy in the form of dark radiation, well, even better band name, then you

get a dark star. I think a dark star is probably maybe a theoretical object in dark matter. So maybe it's a star made entirely of dark matter. I'm not entirely sure. I guess a dark star would be a star that's not emitting light. So maybe a star that has already undergone a supernova or that has collapsed into a black hole or something. Otherwise, I guess a rock star that trashes hotel rooms would also be a dark star. All right. Interesting answers here.

I feel like all of these answers could be a theory of physics in itself. They are some great answers, and you hear some real knowledge in there. There are people talking about dark matter stars or black dwarves. Black dwarfs are a real thing. Are they? They absolutely are. There are when a white dwarf, which is just a huge hunk of hot metal, no longer actually fusing and giving off light, just sort of like glowing in the universe, when they cool down eventually and stop glowing and become dark. And so that's a black dwarf.

I like this suggestion that maybe it's like a dark matter star, which we actually talked about on the podcast, right? Yeah, we did talk about whether you could make dark matter stars and maybe whether they would make dark photons using dark fusion or something crazy like that. So if you're interested in dark matter stars, go check out that whole episode. I see. But that's a separate rock band, right? There's dark star and there's dark matter star. Yeah, I think they toured together once in the 80s, but it didn't go very well. The extra dark tour is epic and historic.

Well, they never turned on the lights and so nobody could tell if they were there. Yeah, they just heard music. All right. And then someone at the end said that maybe it's a black hole. So they were sort of close to the truth here, maybe. Yeah, yeah. Maybe they are masquerading as black holes. All right, let's jump into this subject of whether or not a black hole is actually a black hole. And what else it could be? So let's start from the basics, Daniel.

Why do we think we've seen black holes? It's a really fun story, actually. We did a podcast episode about the discovery of black holes. And it's really cool to trace the history of the idea. and then the history of the observation. Like, this is not something I think we could have ever discovered if we didn't know to look for it. Because in the end, the evidence is not a smoking gun.

It's like the kind of thing you can hunt for, subtle signals of if you know to see it. So it's sort of like, you know, a story, the moral of the story is you should really think carefully about what's out there in the universe because it might give you crazy ideas for what to look for. And this crazy idea came from Albert Einstein himself in 1915. when he came up with general relativity,

which is a way to describe how space bends in response to mass and then how mass moves through that bent space. That's the theory of general relativity. And just a year later, somebody solves his equations and discovered they predicted something really, really weird. And that's when the idea of a black hole was born, now more than 100 years ago. Right. Maybe you can step us through this a little bit.

So what was Einstein looking at? He was looking at equations of gravity and what happens if you get enough gravity or mass into one? one tiny spot. How does that affect the equations that he was coming up with? What exactly was he looking at? He was looking for a general equation, one that described, you know, how space bends when you have mass in it. So if you put a sun here and you put a planet there, then how does space curve? And then how do things move through that curved space? But his equations are famously hard to solve. Like we can't solve them for even very basic simple scenarios like a sun and a planet.

We've only been able to solve them for very simple situations like an empty universe with nothing in it or a universe like filled smoothly with matter with no lumps or bumps at all. These kinds of very simple situations lead to solutions where we say, if you have a certain mass distribution, then I can tell you how space bends. It's not easy for a given arbitrary mass distribution to solve Einstein's equations and know how space bends. It's like it's very difficult. Einstein's equations just tell you like the rules that it has to follow, but it's not. we talked about once in the podcast, knowing the equations doesn't necessarily mean you know how to find a solution. And so even though he had these equations, nobody had ever solved his equations, including Einstein. When he put them out there, he was like, here are the equations.

But just a year later, a soldier on the front lines of World War I, Kurt Schwarzschild, solved them for this crazy scenario where you have an really immense amount of mass all in one place. And so that was the first ever solution to the Einstein equations, this one really weird extreme scenario. And sometimes in math, like the really extreme weird scenarios are easier to solve than the more complicated general ones. I see. So Einstein didn't even think about black holes. He just put out, you know, general equations for like everyday life. And somebody looked at that and say, well, why do I crank up the mass and put it on to one spot? That leads to like a special solution, which is a black hole. Precisely. And Einstein was like, wow, nice work. Never thought

of that. That's very cool. He was like, man, panning himself on the back. kind of like, wow, that's a pretty awesome thing that came from something I did. Yeah, I think it's always cool in science to see somebody follow up on your work. You know, you don't want to write a paper and then have nobody read it and nobody respond to it. You want people to read it and build on it. And of course, lots of people have done that for now. But this was like the first step. This is the first time somebody took his equations and said, all right, you know, what kind of universes can this describe?

So Einstein hadn't really thought about this idea of like a volume in space that if you go into it, you can never escape. No, he'd not thought about that at all. And in fact, even though this solution existed in general relativity since the, you know, 1916, people didn't really understand the impact of it, the concept, what it meant, you know, what it would actually look like in space until decades later. It was like in the 50s that this concept of an event horizon was even invented. You know, before that, people were like, well, what would that mean? Would it just look like sort of a frozen star because there's so much gravity to be crazy time dilation? So it wasn't until the 50s that people realized that no one. information could leak out of this, that there was like a barrier beyond which all information

was hidden. So it takes decades sometimes to understand the consequences, even of theoretical ideas. Interesting. So I guess a black hole wasn't really a black hole for for 40 years until somebody figured out that, you know, if you actually were in the presence of one, it would look like a giant black ball. Yeah. But even then, it was like a crazy idea. And you have to understand physics is filled with crazy hypothetical ideas that nobody believes are real. And nobody thinks actually exist in our universe. Like if you read papers, there are papers describing all sorts of crazy bonkers things. And these are just theorists exploring, like what could happen?

What about this? Could this work? What would it mean? And this was in that category for a long, long time, not something anybody ever expected to see in the universe or actually observe. And that changed in the 60s when there was the discovery of neutron stars. And we had a podcast recently about the discovery of pulsars, which was very cool. That shocked people because these are closely related to black holes.

very dense, very compact objects with incredible gravity. So people start to think, hold on a second, if neutron stars are real, could black holes be real also? So neutron stars are totally different because you can still escape a neutron star, right? Yeah, they don't have an event horizon, but they are crazy dense gravitational objects. Okay. So we found it and that made people think, hey, maybe this other crazy idea called the black hole exists out there.

Let's go look for it. Yeah, and then around the same time, we started seeing unexplained radiation from the sky like people were sending rockets up into the upper atmosphere to measure the radiation from space and they found an incredibly bright x-ray source that nobody could explain like something out there was generating very very high energy photons to have high energy photons you need like really really hot gas and you know you look in the sky and you don't see anything there so you're like what's out there it's dark and is generating this crazy x-ray source so that was weird and interesting. Well, I mean, it's dark in like the visible light spectrum. Is that what you mean? Right? Like you can't see with a naked eye, but if you have an x-ray telescope, you can see the light in that frequency. Yeah. So that tells you there there's something out there, which is glowing only in this very, very high energy photons. That's weird. You know, and so we knew it was something and it had to be kind of small because it was like not a whole lot of room around there. You could like pinpoint where this was coming from and it couldn't be some like huge massive extended object because there was like other stuff nearby. And that was like,

was the sort of the second clue. Like we saw that there was something out there that was dark because we couldn't see it in the visible light, but it was generating these x-rays and it was pretty small. We found another example of one that was orbiting a super giant blue star and was emitting this crazy radiation, but there was nothing visible there. And there wasn't a lot of room for anything. So that suggested it had to be something which was like very small, but very high energy. Did you call them like X stars or XS instead? They were so small, extra small. All right.

So then people went out to look for black holes, but I guess the question is, was what they found actually black holes? So let's get into that question and what this dark star is and what it means. But first, let's take a quick break. Have you ever wished for a change but weren't sure how to make it? Maybe you felt stuck in a job, a place, or even a relationship.

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Listen to these women and more on She Pivot's, now on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. The U.S. Open is here. And on my podcast, Good Game with Sarah Spain, I'm breaking down the players from rising stars to legends chasing history. The predictions, will we see a first time winner and the pressure? Billy Jean King says pressure is a privilege, you know. Plus, the stories and events off the court and, of course, the honey deuses, the signature cocktail of the U.S. Open. The U.S. Open has gotten to be a very fancy, wonderfully experiential sporting event. I mean, listen, the whole aim is to be accessible and inclusive for all tennis fans, whether you play tennis or not. Tennis is full of compelling stories of late. Have you heard about icon Venus Williams' recent wildcard bids or the young Canadian, Victoria Mboko, making a name for herself? How about Naomi Osaka getting back to form?

To hear this and more, listen to Good Game with Sarah Spain. I heart women's sports production in partnership with deep blue sports and entertainment on the IHeart radio app, Apple Podcasts, or wherever you get your podcasts. Presented by Capital One, founding partner of IHeart Women's Sports. Imagine that you're on an airplane and all of a sudden you hear this. Attention passengers. The pilot is having an emergency and we need someone, anyone, to land this plane. Think you could do it? It turns out that nearly 50% of men think that they could land the plane with. the help of air traffic control. And they're saying like, okay, pull this, until this.

Do this, pull that, turn this. It's just, I can do it my eyes close. I'm Manny. I'm Noah. This is Devin. And on our new show, no such thing, we get to the bottom of questions like these. Join us as we talk to the leading expert on overconfidence. Those who lack expertise lack the expertise they need to recognize that they lack expertise.

And then as we try the whole thing out for real. Wait, what? Oh, that's the run right. I'm looking at this thing. Listen to no such thing on the Iheart radio app, Apple Podcasts, or wherever you get your podcasts. Hey, sis, what if I could promise you you never had to listen to a condescending finance, bro? Tell you how to manage your money again.

Welcome to Brown Ambition. This is the hard part when you pay down those credit cards. If you haven't gotten to the bottom of why you were racking up credit or turning to credit cards, you may just recreate the same problem a year from now. When you do feel like you are bleeding from these high interest rates, I would start shopping for a debt consolidation loan, starting with your local credit union, shopping around online, looking for some online lenders because they tend to have fewer fees and be more affordable. Listen, I am not here to judge. It is so expensive in these streets. I 100% can see how in just a few months you can have this much credit card debt when it weighs on you.

It's really easy to just like stick your head in the sand. It's nice and dark in the sand. Even if it's scary, it's not going to go away just because you're avoiding it. And in fact, it may get even worse. For more judgment-free money advice, listen to Brown Ambition on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. All right, I know we are questioning black holes. Are black holes actually black holes? Like in the sense of the concept of a black hole that Einstein has.

help figure out, or maybe there could be something else that acts like something that could be a black hole. Yeah, I feel like we're in, you know, act two of some murder mystery where we have a bunch of clues and we have a suspect and we're like, all these clues point to that suspect. And then we're wondering, hold on a second, is it possible that it was actually the ex-husband or the son or whatever one character that you didn't pay attention to and you have to reassess your evidence? You're like, what do we actually know about who killed this person? So this is the part where you like twiddle your thick mustache and like hmm what if yeah you know maybe that was just a paste on mustache or maybe they shaved their mustache off or something or you know the whole thing was just a deep fake and so i think

it's useful to like catalog exactly what we do know about these objects that we've been calling black holes but maybe it's really just the ex-husband or an ex black hole husband anyways so you were telling me that we sort of figured out and theoretically that there could be black holes out there and then we saw some clues and then we actually went and found what we think are black holes. Yeah, we have identified these objects out there in space

and essentially we know that they are small, that they are dark and that they are heavy. We know they are small because sometimes we see other stars orbiting nearby them and coming very, very close. So they can't be that big. We know that they are dark because they don't give off

a lot of visible radiation or almost none or exactly none. And we know that they are heavy because we can measure their gravitational impact on other stars nearby. We see stars like whizzing around them really fast, which only happens to have like a lot of gravity.

So we have something that's small and dark and heavy. And for a long time, we had, you know, only one candidate that could fit the bill, one candidate that could satisfy all of those requirements. And that was black holes. Oh. So I guess, yeah,

I guess from a far enough distance, that's how you would define it, right? If you're far away enough, it's just something that is not visible in the invisible light spectrum, but it's also very heavy. Yeah, because we've never like actually seen an event horizon in the sense that we have like dropped something in it

and see it disappear, you know, or measure the gravitational impact on it. Even the direct photograph we have of a black hole, right, the one that was a big hull balloon in the news and et cetera. Like what is it really? What you're looking at is an accretion disc is the gas around the black hole and in the center you see something black. So again, you know that it's,

small, that it's dark and it's heavy. You don't actually know its nature. And the argument that it's a black hole is basically like nothing else can do that. So if you can think of something else that can do that, then, you know, maybe it's that other thing instead. But we've also seen gravitational waves, right, from black holes or what we think are black holes crashing into each other. We have exactly. We've seen gravitational waves from black holes merging, from neutron stars merging, from neutron stars and black holes merging. What does that tell us? It tells us a again, that there's something very massive with a lot of gravity and that general relativity mostly works.

So that could be explained by something else, you know, just as massive and small and dark in that same location. That would also emit gravitational waves. Like anything that dense and small would emit gravitational waves also. So that's also not a unique signature of black holes. Like let's not jump to conclusions. And so maybe a possible thing this could be instead of a black hole or something called call the dark star. So like what is a dark star then? Yeah. So the idea is, you know, exercise your

brain. Think about other ways to arrange matter that gives the same sort of outward appearance, but looks different fundamentally. And so a dark star is like, again, very, very dense matter. You know, you take star and it's done burning. And so it no longer can provide like radiation pressure to push outwards and gravity takes over and it pulls the star in and it collapses into something very, very dense. And there's lots of different scenarios. One scenario is it becomes a neutron star, right? And that's a scenario where it avoids total gravitational collapse because of the neutrons

putting pressure on each other. But there's this other idea that it could collapse to something even more dense than a neutron star, but not a black hole. And so that's what a dark star is. It's got something called a plank core where the core is collapsing gravitationally, but it doesn't go all the way to a black hole because something prevents it. Something does actually push back. Interesting.

Yeah, I remember a neutron star, it's like the stuff is squeezed together so much that it like dissolves into almost pure quarks, right? And so you have this giant ball of quarks kind of holding together because there's enough energy there to pushing the corks pushing each other away, but it's still super, super dense. Yeah, and we do not understand the internal physics of the neutron star very well at all. It's like a really active area of research. And it's really difficult to study because corks are complicated. You know, they use the strong force, which is a big mess to do calculations in. Every time you emit a gluon, it emits more gluons. You have infinite numbers of gluons every time you want to do a calculation.

So we don't really understand what's going on inside a neutron star, but roughly, yes, it's like a huge particle because all the quarks are bound together and do this incredible, you know, like 10, 15 kilometer object. That's the mass of the sun. So you're saying that there's another step that you can take between that and a black hole, which is maybe a dark star. And so what's happening? Are the quarks somehow running out of juice? And so they squeeze in a little further?

Like what's going on? How would this dark star come to be? Yeah. So the reason a neutron star is stable is because the quarks are pushing back against each other. And so to go deeper and darker and go beyond a neutron star, you need more gravity. So if you have more mass than a neutron star can be. Like neutron stars can be at most, you know, mass maybe twice the mass of the sun or so. We're not exactly sure.

But if you have more mass than that, then you can have enough gravity to overcome what the quarks are doing to resist the collapse. Just the same way like our sun currently is resisting gravitational collapse, it's doing so by burning and his fusion and photons pushing out. The neutron star is pushing out because of the quark forces. If you have more gravity, you can overcome that, then you can go deeper. And there's another layer people think, this is all hypothetical, people think that there's another layer where quantum mechanics itself prevents you from getting to a black hole.

So the particles get so close that the particles get so close that the, The quantum mechanics uncertainty principle prevents you from collapsing even further. Interesting. So I would have like a neutron star super dense and I add more neutrons to it, more mass to it. And before it actually collapses into a black hole, maybe there's something about quantum mechanics that keeps it not collapsing. Because quantum mechanics doesn't like having particles localized in a very specific region. The whole idea of a singularity inside a black hole, huge amount of mass.

in basically zero volume is nonsensical when it comes to quantum mechanics. Quantum mechanics says if that happens, then the uncertainty and the momentum of all those particles would basically be infinite, so they would basically have infinite energy and then they would escape. So the whole thing of a singularity doesn't make sense from the point of view of quantum mechanics. So the idea is maybe quantum mechanics prevents you from getting there, that as the particles are collapsing, that the uncertainty principle prevents them from getting so close as to actually form a singularity. I guess the key thing here is that it's small, it's dark,

it's super dense, but it's not technically a black hole because it doesn't get dense enough to form an event horizon, which is like the actual point where nothing can escape. Yeah, this dark star would not have an event horizon exactly. And also it wouldn't have a singularity at its core. You know, the really defining characteristics of a black hole are the singularity at its core and the event horizon. And so this would be a very, very dense object, even denser than neutron stars, but not actually a black hole.

And quantum mechanics would be preventing that. And something else that's super fascinating about these objects is that they're not stable. Like a neutron star is stable. It's a balance between these two forces squeezing down gravity and pushing out because of the quarks. This plank core is not actually stable. People think that quantum mechanics is more like a rubber sheet, you know, that you're like, it collapses and then it bounces back. So it provides like a maximum density or like a minimum size to this object,

and then it pushes back and then the star expands again. But wouldn't that be evidence? evidence or an argument against these dark stars, like if they don't last very long, why do we think they could exist? Right. Well, they might not last that long in their own time, right? But the gravity is really, really intense. And so time is slowed down. So what these dark stars might be is like this object that's collapsing that's going to bounce back from this plank core. But from our point of view, it might take billions or trillions of years for that bounce to happen because it's super slowed down by the gravitational time dilation.

So it looks stable to us on our time scale, but if you're inside of it, the whole thing would be over in a blip. It's like a loophole. Like it's unstable and it won't last for long, but it depends on what you mean by long. All right, so from our point of view, it would look like a stable thing, but it's actually not.

Yeah, and it doesn't have an event horizon. And so unlike a black hole, it could actually emit information. It could like actually leak photons. But I guess why is it dark and why is it? it emitting x-rays but not visible light? Yeah, great question, right? Because we have to match all the observations for these things to explain what we see.

They have to actually predict what we see. So how could these things be dark? Again, it's gravity and the relativistic effects. If these things really do have this much gravity because they're very, very dense objects, so much so that they have this crazy time dilation, they have another effect on things, which is that they red shift. So they might be emitting photons, but those photons would be shifted towards the red so far towards the red that they're essentially invisible.

Like, take a visible light photon that has a wavelength of, you know, a few hundred nanometers and stretch that thing out past infrared, out past radio. So it has like a wavelength, you know, like the size of the galaxy or maybe a little smaller. That would be a photon that's so big, it would be almost invisible. And so this would look like a black hole. Wow, photon, the size of a galaxy. That's wild. Well, let's get into why we think these dark stars might be real.

and whether or not they actually maybe supplant black holes and make them not real. But first, let's take another quick break. Have you ever wished for a change but weren't sure how to make it? Maybe you felt stuck in a job, a place, or even a relationship. I'm Emily Tish Sussman, and on she pivots, I dive into the inspiring pivots of women who have taken big leaps in their lives and careers. I'm Gretchen Whitmer, Jody Sweeten. Elaine Welteroff. I'm Jessica Voss.

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The pilot is having an emergency, and we need someone, anyone, to land this plane. Think you could do it? It turns out that nearly 50% of men think that they could land the plane with the help of air traffic control. And they're saying like, okay, pull this, do this, pull that, turn this. It's just... I can do it my eyes close. I'm Manny. I'm Noah.

This is Devin. And on our new show, No Such Thing, we get to the bottom of questions like these. Join us as we talk to the leading expert on overconfidence. Those who lack expertise lack the expertise they need to recognize that they lack expertise. And then, as we try the whole thing out for real. Wait, what? Oh, that's the runway. I'm looking at this thing.

Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hey, sis, what if I could promise you you never had to listen to a condescending finance bro? Tell you how to manage your money again. Welcome to Brown Ambition. This is the hard part when you pay down those credit cards. If you haven't gotten to the bottom of why you were racking up credit or turning to credit cards, you may just recreate the same problem a year from now. When you do feel like you are bleeding from these high interest rates, I would start shopping for a debt consolidation loan, starting with your local credit union, shopping around online, looking for some online lenders because they tend to have fewer fees and be more affordable.

Listen, I am not here to judge. It is so expensive in these streets. I 100% can see how in just a few months you can have this much credit card debt and it weighs on you. It's really easy to just like stick your head in the sand. It's nice and dark in the sand. Even if it's scary, it's not going to go away just because you're avoiding it. And in fact, it may get even worse. For more judgment-free money advice, listen to Brown Ambition on the IHeart Radio app,

Apple Podcasts or wherever you get your podcast. All right, we're talking about dark stars and whether the things that we call black holes are actually maybe not black holes. And maybe there are these dark stars. And so we talked about what those are. Now, Daniel, why do we think that maybe black holes are not black holes, but that they're actually these so far theoretical dark stars? Yeah, well, one reason is that black holes. holes are a headache. You know, they don't really make sense. There's lots of puzzles. Like, they're fascinating. They're amazing. They're sort of a fun headache. But, you know, there's lots of

things about black holes that we don't understand. Like, can a singularity be real? Is that something which actually exists in our universe? You know, as we said, general relativity predicts that singularities are real, but quantum mechanics says they can't exist. And so we've long struggled to understand that contradiction. And so this is sort of like a way around this to say like, oh, well, maybe they just never happen. And so we don't have to explain them. So would this supplant even like the black holes we think are at the center of galaxies? Like could those super massive black holes in the center of galaxies that we know are humongous?

Could that those actually be dark stars? Or are we only talking about the smaller black holes? No, we're talking about all of them. So we could supplant all of them. And you asked a question before the break about the x-rays. Like how do we explain the x-rays and the other radiation? Because the super massive black holes at the center of our galaxy, you know, from the actual black hole, there's no light, right?

They are black, but around them are these crazy accretion disks of hot gas that are emitting x-rays and other very high energy radiation. But that's just from the gravity of the object. And so a dark star with the same gravity as a black hole, but without the actual singularity in the event horizon, would have the same gravitational impact on nearby stuff, heating it up and swirling it around and generating that same radiation. So, yeah, you could have a huge dark star at the center,

of our galaxy that's like in the middle of a billion or trillion year collapse and rebounds out, but it looks to us like a black hole. I feel like you're kind of saying that maybe black holes in themselves are impossible. Like maybe it's impossible to have a black hole. And actually like when you try to get a black hole, the most you get is one of these like super compressed dark stars which are being kind of prevented from collapsing by quantum mechanics. Yeah, exactly. And so maybe the reason that black holes make the,

no sense theoretically and inconsistent with quantum mechanics is because quantum mechanics prevents them from happening, right? If the universe really does follow these rules or the uncertainty principle, then that's inconsistent with singularities. And so maybe the uncertainty principle prevents the singularity from ever forming. Oh, man, I feel like you just blew my mind. You've had how many podcasts about black holes and now you're telling me like maybe they're not actually real.

Like maybe they're impossible. Yeah. And in some sense, like coming up with this other explanation for them solves all these other problems that black holes bring with them. We've had multiple episodes about like the black hole information paradox. We know the quantum information is not destroyed. So what happens when things fall into a black hole? What happens to their information when the black hole eventually evaporates? We don't know. It's not something that makes any sense to us. And we can't explain because we have no good theory of quantum gravity that tells us what happens when there is gravity between particles.

And so maybe the solution of that is just scratch black holes. the list of things we want to explain, right? We don't need to explain. Forget about it, you know, like, never mind, you know, this thing we've been talking about forever. Oops, never mind. It's actually not possible. Yeah, it's really fun idea, you know,

like take something off your to-do list by erasing it instead of doing it. Yeah, I got to clean the toilet. No, toilets don't exist. Done with that. Yeah, you're going to have other problems if you think toilets don't exist. But the cool thing about dark stars is not only. only do they get rid of this thorny problem of black holes, but they could explain other mysteries of the universe that are out there.

Yeah, other dark and mysterious stuff, right? Yeah. For example, we've long wondered, you know, what is the stuff out there in the universe that's creating all this gravity that seems to be holding the galaxy together? Some weird new kind of matter that we don't know what it is and we can't see it, but it has gravity and it's affected the structure of the universe and it affects how galaxies spin. and it seems to be everywhere and really important and it's more of it than there is a normal matter,

but we don't really know what it is and we haven't been able to see it or interact with it or detect it. So this stuff, dark matter, we have a long list of candidates for what it might be. But now, because of dark stars, we have sort of a new candidate that appears on that list. And that's these crazy long wavelength photons. So you're saying that the light from these dark stars

is what could be dark matter, or are you saying that maybe the universe is like riddled and filled with tiny dark? stars everywhere. No, it's the light and the radiation from these dark stars. So these dark stars look a lot like black holes, but they do give off some light. But that light is invisible to us because it's so low frequency. And that light itself might be the dark matter. It could be that there's so much of it out there that the light itself is helping curve space. Because remember, photons have no mass, but in general relativity, space bends in the presence of energy, not just mass. So photons can

contribute to that. And so these things can contribute photons or even gravitons that are hard to detect, but overall having lots and lots and lots of them around, they can bend the shape of space in exactly the way dark matter does. I feel like now you're saying that maybe dark matter doesn't exist and really it's just dark light. Dark stars emitting dark photons could explain everything. But wouldn't black holes also emit, you know, these dark photons? If black holes existed, but black holes don't emit anything, right? I mean, black holes don't emit anything. Right. I mean, black holes don't emit light. The stuff around them emits light. But this is the one thing that would be different between black holes and dark stars is that these dark stars, because they don't have event horizons,

they do emit light. And that light is crazy stretched to low frequencies by the gravitational strength of the dark star. Couldn't we measure these long wavelength light? Couldn't we have a detector to see if they're there? It's very difficult to interact with something that's such a long wavelength that basically just ignores you. That's why, for example, we do radio astronomy because radio waves can go through like clouds of gas and dust and tell us what's going on in the center of the galaxy because to them the clouds of gas and dust are like nothing. And so it's very, very difficult

to interact with those photons. You need a detector like the size of the galaxy almost in order to interact with them. I feel like you're telling me like maybe, you know, the dark matter halo that we know is, or a cloud that is sort of covering our galaxy. Maybe it's just, it's not dark matter. Maybe it's just like one giant photon.

Like one ginormous photon. you know, confusing us. That'd be hilarious. It was like, hi, I'm Bob. I'm a photon and I've been the dark matter the whole time. Yeah, there you go. Dun, dun, we found our culprit. Why didn't you introduce yourself in Act 1, man?

Why did you wait under new to Act 3? That's just bad mystery writing. Well, that's really interesting to think about. But, you know, photons are quantized. A really, really low frequency photon would not have that much energy, right? Because the energy, the photon depends on its wavelength. So in order to explain the dark matter, you need a lot of these. photons. They have to be Bob and like 10 to the 27 of his friends, I think.

Kind of like the nanobot. Maybe they're fooling the ice cream flavor of the galaxy. Yeah. And you know, this is a fun theory for people to think about. Like, could this be? Could this really exist out there in the universe? What are ways we could separate them from black holes that we could actually detect? But it's a new area people are playing with it. You know, Carlo Revelli wrote a fun paper about them. I read a few papers on this topic. It's still something that's in people's minds. I see. Like, we don't know if it's even possible to have these dark stars or whether they would just collapse into a black hole. Yeah, the science of them is still very new and tentative and people are doing calculations

and making all sort of assumptions and disagreeing with each other about what these things might look like. It's really at the forefront of knowledge. But, you know, black holes were at the forefront of knowledge for decades before we understood really what they would mean and what they would look like in the universe. And so it might just take a little while for sort of like people to digest this stuff intellectually and figure out how to look for them correctly. Well, I thought that picture that we took up to black hole last year or two years ago was pretty convincing.

But now when I look at it, maybe I'll imagine a little tiny bob in the middle there laughing at us and twiddling its mustache. Yeah, exactly. Maybe it has a totally jet black mustache and you can't see it. And it's laughing at you. And admitting dark matter. That's crazy. All right. Well, I guess once more, the universe is full of potential surprises.

And I guess the main lesson here is don't trust physicists, you know? Maybe they know what they're talking about. No, no, no, rewind this whole podcast. No, the lesson is fund physicists to think of crazy ideas because they might find stuff that's actually out there and then they might come up with even better explanations to describe what you see. We definitely need creative brainstorming about how the universe works.

That's a good positive spin. All right, well, we hope you enjoyed that. Thanks for joining us. See you next time. Thanks for listening and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. on the players, the predictions, the pressure, and of course, the honey deuses, the signature cocktail of the U.S. Open.

The U.S. Open has gotten to be a very wonderfully experiential sporting event. To hear this and more, listen to Good Game with Sarah Spain, an IHeart Women's Sports production in partnership with deep blue sports and entertainment on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. Why are TSA rules so confusing? You got a hood of your take it all! I'm Mani.

I'm Noah. This is Devin. And we're best friends and journalists with a new podcast called No Such Thing, where we get to the bottom of questions like that. Why are you screaming? I can't expect what to do. Now, if the rule was the same, go off on me. I deserve it.

You know, lock him up. Listen to No Such Thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. No Such Thing. I'm Dr. Joy Hardin Bradford. host of the Therapy for Black Girls podcast. I know how overwhelming it can feel if flying makes you anxious. In session 418 of the Therapy for Black Girls podcast, Dr. Angela Neal-Barnett and I discuss flight anxiety.

What is not a norm is to allow it to prevent you from doing the things that you want to do, the things that you were meant to do. Listen to Therapy for Black Girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. This is an IHeart podcast. Thank you.