Daniel and Jorge Explain the UniverseCould mysterious black holes have been formed in the first second of the Universe?
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Hey, Daniel, you believe in the power of words, right?
I hope words have power. I mean this podcast is literally just words. It's our superpower.
Yeah. But also, don't you think individual words have a certain energy to them?
You know? I think some words are just like inherently funny, you know, words like booger or weasel or plodcast.
Yeah, there are goofy words. But some words have drama to them, you know, like dragon or chaos.
Man. The combination there makes me think of things like dragon, boogers or chaos weasels.
Actu. I was thinking more like dragon weasels. That's a scary word.
I don't know that's scary or silly.
But what about some science words? Do you think some science words have power to them?
I don't know. I feel like this is a trap. You're always making fun of our science names. You know, charm, quark, big bang.
Those are charming words, indeed, But I mean, can you blame me? Do you guys ever come up with dramatic names, cool names?
I got something up my sleeve, you got something out of the dawn of time?
All right? This better be good?
Oh yes, it is positively prime mordial.
I am Orham, a cartoonist and the creator of PhD Comics.
Hi.
I'm Daniel. I'm a particle physicist, and I believe in the power of words to entertain and educate.
Welcome to our podcast, Dragon Boogers.
Brought to you by two podcasting Chaos Weasels.
No, I'm just kidding. Welcome to our podcast Daniel and Jorge Explain the Universe, a production of iHeartRadio in.
Which we use words to take you on a mental tour of the universe. We take you all the way back to the beginning of time, We take you to the edge of time. We take you down to the tiny particles and out to the largest things in the universe, and we share with you our wonder, our joy, our curiosity for how everything works and what science is doing to try to figure it out today.
Yeah, it goes straight from our brains and our hearts through the Internet into your ears, and straight into your brains and hopefully your hearts as well.
That's right through that weird system of tubes. That is the intent.
We should talk about that one day, Daniel and Jorge explain the tubes. But there are a lot of amazing things out there in the universe to see and to discover and to learn about. And some of the things have been around for a very long time. I mean, the universe is it's pretty old or maybe pretty young, depending on how you look at it.
That's right, And there are a lot of amazing things out there to understand. Stars, exploding stars, collapsing, black holes forming. Some of these things that you're already amazed by might have a very different history from the one that you're anticipated.
Yeah, because I think sometimes knowing the history or something gives you a better perspective about it, you know, like if you know where it came from or what it was like before, it kind of tells you a lot about something.
Yeah. Well, that's basically the whole game of astrophysics, right. We are looking at the universe, which is nothing but a series of clues as to how the universe was made, and from that set of clues we try to unravel the mystery of what came first and what came second, and what does that mean about what's coming next? Right, So the history of like how things were put together is really central to all of science and all certainly all of astrophysics.
Yeah, and I think one of the things that fascinated most people about the universe is this idea of black holes. I mean, black holes are just kind of amazing, aren't they. They're so they're so weird and so kind of a mysterious.
I know, and in so many ways. You know, you have the fact that they first started as a theoretical idea, like just a solution to equations and pencil and paper, the idea that just this concept, the scratching of graphite on paper could predict crazy things happening out there in the universe. That's mind blowing. Yeah, and then you know the drama in which they are formed, the end of the life of a star, this cataclysmic collapse, the supernova that precedes them. I mean, you couldn't write anything better than that if you were a fiction writer.
Yeah, there was drama in how they were discovered and how they were thought of. I mean, Einstein came up with these right in his equations and it literally just came out in like math first.
Yeah, it just came out of the math. You know, you look at the universe, you try to understand how it works. You write down some equations that describe what you see, and then you explore the weird edges of those equations. You say, well, what else could these equations predict what happens in these other weird scenario? And then you go out and if you believe those equations are real, that they're describing something real about the universe, you go out and check those predictions and see, well is this just a weird figure of math or is this something that actually happens. And so it's incredible when you've achieved that, when you've really described the universe, You've pulled back a layer of reality and said, here are the fundamental underlying mechanisms, and I can prove it by showing that I can predict what they do.
Do you think Einstein called them black holes right away? Or what did we call him when he saw him on the math page? You know, he saw these things sort of singularities, and he predicted that light couldn't come out of them. Did he have a name for them?
Well, you're right that the modern idea of black hole certainly came out of Einstein's equations, but the concept of a black hole actually predates Einstein. The idea that you could have an object that had so much gravity that light could not leave it. The concept of that predated Einstein, so that the phrase black hole was already sort of existing.
Interesting, all right, And we've also now had I've seen black holes, right, we have pictures of black hole.
That's right. We've known for a while that there are black holes at the centers of galaxies, and we've seen that because we look at the way the things swirl around and the gas and the dust that emit from those galaxies. So you can't see the black hole directly, but you can see the sort of swirling chaos around it, you know, the chaos weasel, if you will, of the universe. And we've also seen smaller black holes, black holes that are formed when stars collapse, and we can see those sometimes via lensing, when they pass in front of other stars.
So black holes are amazing and interesting and mysterious, and there are a lot there's a lot about them when that we don't know that. We don't know what's inside of them. We don't know how big they can get, and how the ones in the center of galaxies come together. We also sort of don't know how old they are, right, It's hard to tell because they keep so well, that's right, They stay fit.
They are pretty stable. They last a very very long time. And you're right that we don't know so much about when they were made. I mean, one mode of making black holes is you have a star and it collapses, and then you have a black hole about the mass of a star or several stars, et cetera. Another is these black holes the very center of galaxies that are millions of suns. But there's the possibility that black holes might even be older than that. They could even be older than the first stars.
Really, oh man, I thought black holes only form from stars. But you're saying they could be older than the ideal stars.
That's right. It could be that there were black holes formed before there were even particles. Black holes formed in the very first few moments of the universe.
It pre date matter, predate matter.
Yes, exactly. Wow, and so.
What what what?
What?
Well? How could it have anything inside.
Exist?
I know, we'll dig into it. But these things go by the awesome name of primordial black holes.
Wow, that is a cool name. All right, So then that's a question for the episode today. Today on the podcast, we'll be tackling the question what are primordial black holes?
That.
It's kind of a hard word to say, but it sounds cool when you say it. Primordial.
I know, primordial. It sounds like primeval or something. You know, it sounds like something is crawling out of a swamp somewhere.
Yeah, it feels like raw and like unform and like, oh my goodness, it it predates things.
Yeah, it's like from the Age of Giants. You know. It's like if Thor had a black hole, it would be a primordial one for where.
The wild things come from.
Kind of exactly. I don't think it's a children's book, primordial black holes, but it's a really cool word. And it also it touches on that mystery. Right, we don't know what happened in the first few moments of the universe. We don't know how things worked, and so it'd be amazing if there were things left over from those very first few moments that would be fascinating.
So it's kind of a cool concept, and it's kind of also kind of a recent concept. I feel like, you know, like Eistein wasn't talking about primordial black holes, right.
No, definitely not. This is definitely a more recent concept.
So, as usual, we were wondering how many people out there had heard of these primorial black holes and or had any idea of what they were. So Daniel went out there into the wilds of the Internet to ask people what are primordial black holes?
That's right, I went out into the primordial Internet, which consists of emailing our listeners and asking them to volunteer to answer spontaneous questions. So thank you to our listeners who participated. If you would like to answer spontaneous questions and hear your uninformed speculation on the podcast, please write to Questions at Daniel and Jorge dot com.
So before you hear these answers, think about it for a second. Have you heard of primordial black holes? Or would you know what to answer if asked this question. Here's what people had to say.
I've got nothing on that. I would guess that it's from really early in time, really large black holes. I would guess that it's probably the ones that are at the center of the galaxies, but not sure.
Well, like they are the oldest blackhole, or the first one.
Was prey we're.
Pray, yeah, maybe one of the biggest black holes in the universe, or yeah, the first ones.
Primordial black holes are black holes that were created by the original plasma of the early universe before expansion began to occur. As the matter collapsed and condensed, it became black holes that have persisted since the dat of time. Basically, I think the black hole at the center of our galaxy is a primordial black hole.
Black holes in the center of galaxy the biggest ones.
A primordial black hole is a gravitational well created at or just after the initiation of expansion. My understanding is that they consist of mass magnitudes of order larger than super massive black hole holes. Perhaps gravitational waves from these primordial black holes leak through the multiverse and are perceived by us as dark.
Matter primordial black holes.
This is really kind of difficult, Like, is it the original black hole? Is it what started the Big Bang? I have no idea about that. Excited to find out.
Though.
Primordial black holes are black holes that formed way back at the start of the universe, just after the Big Bang, once inflation had happened and everything else. There were pockets of densities left that caused these black holes to be created Nigeria, hawk and radiation. It's unlikely that any of them still exists. However, they could have caused the start of all the other black holes within the universe.
I think black holes that were made during the Big Big Bang, maybe they are still old there.
My guess is that it's a cooler black hole that's like more special than your average ones, so it got its own name.
So I think promoter of black holes are black holes that formed shortly after the Big Bang, so that they're really old black holes. But I don't know much more than that.
All Right, these are pretty good answers. It seems like the ward definitely evokes feelings in people. You know, there are like a lot of people say it's before the dawn of time or before the beginning of time.
Yeah, on the ooze that we walked out of. That was a great answer, And I think that means that this is well named, right, wouldn't you give this high marks, like if people could guess what it means.
Well, I don't know what they are yet, Daniels anything, their judgment is still out. Maybe this is a better word for me.
I'm feeling a little bit of hesitancy to say anything positive about physics naming. But I'm gonna come back to this at the end of the episode.
Oh, I see, this is the one you would submit to the naming words.
This one's high on my list.
Yeah, I see. We came out with one good name.
We're not looking for awards, We're just looking for, you know, to no longer be criticized. I see he's getting a lot of flak here.
She's looking for approval. Physicists just want to approve. All right, Well, let's get let's jump right into it, Daniel. What is the primordial black hole and how is it different than a brand new black hole?
Yeah, so brand new black holes, the sort of garden variety black holes that you're familiar with, are the ones formed when stars collapse. You have a big blob of normal matter, you know, quirks and electrons and all sorts of stuff gas and dust, and after it's done fusing, gravity pulls it together and you get this dense spot in space where light cannot escape. So that's your normal black hole. And the critical thing to making a black hole again is having a very dense blob of matter, so much matter that it's bent space, it's spent space in this way that like the inside of the black hole is cut off from the rest of the universe. It's stretched space in such a way that every path in the black hole goes deeper inside none of them come out. And so you can visualize it as light cannot even escape because the force of gravity is too strong. But the more modern way to think about black holes and gravity is about bending of space. So these things create these weird structures in space that there's no path out of even if you're traveling at the speed of right.
Right. They sort of bend space so much that they kind of form a hole, almost like a hole in space.
Yeah, they sort of form a hole in space. You can think of it like the universe has become separated, and there's now this little piece of the universe that there's only a one way door into and once you go in there, you can't come out to the rest of the universe.
It's just impossible, right, And like you said, it takes a lot to form a black hole. I mean they're so extreme that you know you can't just like it's hard to pack that much mass into such a small space that you know you need something like a supernova or a star collapsing for that to happen.
Yeah, the key thing really is density. You can make small black holes, but you need some very strong force to squeeze the mass into a very small space. The smaller the mass, smaller the space, and the denser it has to be. And black holes can vary from fairly small masses to enormous masses like millions and millions times the mass of the Sun.
Yeah, those are super duper black holes. Yeah, I think that's the official tournament.
In extra califragilistic black holes.
With the spoonful of sugar.
And this is the kind of thing we've seen in the universe. We predicted it. We understand the stellar mechanics, we understand the force of gravity, we understand what goes into it. Our numerical stimulations makes sense. We observed them. Everything sort of fits together, right.
You can see them like floating around in the center of the galaxy. These are like well known.
These are well known, they're well established. Nobody doubts that these black holes exist. And we've counted them, and they exist or roughly the rate you would expect. And you know, it's a it's an awesome feel of study, but one that doesn't have that many surprises in it. But those are stellar black holes. Those are black holes formed from matter that was created after the Big Bang. Right, it's this whole other category of black holes, these primordial black holes that could have been made in the very first few moments of the universe.
Right, because things were pretty crazy at the beginning of the universe. Right, it was like a loud and wild birth for the universe.
That's right. It was hot and nasty and wet, and you know, you might think, well, what do you need for making a black hole? You need a dense blob of matter. And you know, early in the universe there was a lot of matter and it was very dense, and so you might expect there to be black holes made in the early universe. It's not that surprising to think that there would be blobs of matter capable of forming black holes.
Right, And in fact, this was a listener question we got a while ago, about as somebody asked, why didn't the universe just collapse into a black hole at the beginning of time? How are we here? Amazing question? It's like, we're here, how come right? Because things were so dense at the beginning of time? Why didn't it just all collapse into a black hole?
That's right, It's a great question because things were really dense. And one of the ways answer that question is that black holes and you need to be localized. You can't have the entire universe collapse into a black hole if everything is perfectly smooth. To form black holes, you need hot spots of density. You need the black hole to form somewhere to pick where the black hole forms. You need some spot to be denser than another spot. If everything's equally homogeneous, then the force of gravity just cancels out.
It's almost like if you're in a hole, you can't have holes. You can have a hole in a hole. Kind of is that kind of the idea, Like either everything's a hole or you only have little holes.
You can't have everything to be a hole because you need extra gravity in one spot. And if everything is smooth, then all the gravity cancels out. I mean, imagine a perfectly smooth universe, even if it's filled with infinite matter, there's no gravitational force on you because in every direction the gravitational force is balanced by matter in the other direction. So to create a black hole, you need a very strong force of gravity, and that can only be created by additional density, by extra density, by hot spots. If it's totally smooth, it doesn't matter how dense it is. You can't form black holes, right.
And so the idea is that during the Big Bang, the whole thing kind oft turn into a black hole. But maybe there are things were so intense that there may be there were hot spots during the Big Bang, the beginning of the Big Bang, and maybe black holes did form in that in those early moments.
Absolutely, and there had to have been hot spots. If there weren't hot spots early on in the universe, we wouldn't be here either. What because the universe is no longer perfectly smooth, right, A perfectly smooth universe stays perfectly smooth or wherever there's no way to disrupt it. So there had to have been hot spots, and those hot spots seeded the formation of the universe and the structure of the universe as we see it. The reason we have matter here in not a billion light years to the left is because of some hot spot in the early universe which very slowly gathered together matter and formed all this structure over billions of years. But those same fluctuations, which came from quantum randomness at the tiny scale, could also have ready black holes. Right, That's exactly what you need for a black holes, like an extra little spot of density, and so it's natural the things that you could have also gotten black holes formed in those early moments when you have those hot spots.
Of density I see, and we're talking like the first few like you know, bazillions of a second after the Big Bang.
Yeah, exactly. This is before you had a chance to even make matter. Right, it's not like a question of is the matter made out of quarks or electrons. There's just hot stuff, right, there is no matter at all. There's just like energy, crazy energy density. We don't even really know what was there. But yeah, this is very very early on in the beginning of the universe, before it even matter was cool, before matter even existed, And so then you could ask the fun question like well of a black hole formed before or matter, like, what's in it? Right? What's it made out of? What kind of stuff is there?
Right? How can it have anything inside of it?
Well, we don't know what it's made out of. If it's made out of whatever was in the early universe, which is unform fortunately still a huge mystery, like what was creating the inflation of the universe, this grand expansion that stretched out these tiny quantum mechanical fluctuations into larger fluctuations that gravity could begin to seed. We don't know, And so we don't know if these black holes were made and what masses they were made at, and what's in them. But it's a huge mystery. You know, we don't even know what's inside current black holes. Like if you take a star and you squish all this stuff together to make a black hole, are there quirks in there still? Are they turned into something else? Weird? Like what's going on inside there? It's one of the deepest mysteries of the universe. So if you take a spoonful of like weird early universe stuff and make a black hole versus a spoonful of like, you know, normal, boring, five billion year old star stuff. Do you get a different kind of black hole? Not a question we know the answer to.
All right, let's get into these primordial black holes. How big they are, what do they look like? And what do they smell like? That's what I'm curious about. First. Let's take a quick break.
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All right, Daniel, we're talking about primorial black holes, and this sounds like the primordial soup kind of of demas well.
I don't know what black holes smell like, but these primordial ones are. They're probably pretty swampy, you know.
In the suit.
But you know, that reminds me if you heard of the black hole no hair theorem. What black holes essentially can't have hair. So if this thing is primordial in swampy, it's also shaved clean. I'm not making that up.
Is this a reference to dinosaurs?
So I'm not making that up. There's a theory that says the only thing that you can know about black holes is their mass, whether they're spinning, and their total electric charge. That's like the only properties they can have. You can know nothing else about what's going on inside of it, what matter was made to use it, whether it shaves daily or you know, lets itself go hairy. And I think that's why they call it the no hair theorem.
Oh, I see, it's like we only know the bare minimum things like hair. We can't know those details.
That's right, We know the bare minimum, and that's all the information that exists. You know. One question is like is there information inside the black hole about what was made? Or is that all the information that exists? And somehow black holes who just like remove that information from the universe. But that's a topic of another podcast.
They're just born bald who knows, right? But all right, so they're at the very beginning of the universe, a very early micro bazillion seconds of the Big Bang. There could have been black holes. And so this is this is making me ask so many questions, like, you know, how are they formed, what were they made out of? How can you can you have a black hole without any matter being around? Do they just have pure energy inside of them?
Yeah? Because you know, gravity is linked to energy density. We think of gravity as connected to mass, but really it's connected to energy density, and mass is just one example of how you can store energy. So you can make a black hole just out of super intense radiation, right, as long as you have enough energy density. It's energy density that bends space that creates what we call gravity, And so it doesn't matter what kind of mass or energy it is, it's just energy density.
I see. And it has to be more dense than the things around it, right, yes, exactly. It can't just be like like having enough energy. It's like you have to have more energy than what's around you so that you can bend space enough to make these pockets.
Yeah, exactly, because if there's also energy or around do de bends based the opposite way, then you don't get that curvature you need. And one thing that's really amazing about primordial black holes is that because they don't have to come from stars. You can make them in other ways, which means you can make them in a whole variety of different sizes.
And flavors.
Probably now there's the no flavors equivalent.
There's an equivalency there, all right.
That's right. They only come in dark chocolate budge.
No.
Because you don't have to start from a star, you can make black holes that are very very small, like primordial black holes might be as small as like one billionth of a kilogram.
Oh wow, all right, so the Big Bang is banging, and there's fluctuations and the energy there, but it's so intense that suddenly you can floor you can pop these black holes in the existence. And you're saying that they could be really small or they can also be really big.
Yeah, it just depends on the mechanism that gives you the energy density. And that's something that's just like wild speculation about one theorist had some idea for how the energy density profile looked, and then gives you a bunch of small black holes. Another one thinks the energy density profile looked different and that gives you a bunch of big black holes. Another one. Most of them actually think that you get a whole distribution that if you make small black holes, you should also make big black holes and intermediate black holes down from like one billionth of a kilogram up to like thousands of times the mass of our son.
All right, so these primordial black holes there, they sort of make sense, right because it was a big bang and why not. But we can't just sort of go with.
There was a big bang and why not? That sounds like you could use to explain anything. Hey, how come you ate all the cookies?
Hey?
Well there was a big bang in dot dot dot the cookies.
I mean, it just seems so crazy. What was happening? Then? Then you know, why not? Four black holes? But we can't just kind of go by what what makes to a cartoonist?
Or Hey, cham why did you climb Mount Everest? Well? You know the big bang dot dot dot?
Why? All right?
I need a T shirt that says that anyway.
Hey Ton, do you want to host the podcast? You know? Big Bang?
Why not?
Sure? If it's about the Big Bang.
We're still in the Big Bang?
So the biggest still banging?
Well, well, why do we think they exist? I guess is there is there more than just kind of the speculation about what could have been happening back there.
Yeah, I mean, it's it's a fun idea. It makes sense that they would exist. But if they do exist, they also might solve a bunch of other problems. And this is a cool way to discover something is to see, like, have an idea for what might be out there, and then think about what else it might explain. And if you can sort of wrap up a bunch of other things that we didn't quite understand then and tell a nice story that all clicks together, then that's the best kind of discovery.
Oh.
I see, we have these other mysteries in the universe, and so now if we can link them to something like primorial black holes, and it would all make sense.
They would all make sense. And one of the biggest mysteries out there is the miss of dark matter. Right, we know that most of the universe is not made out of the stuff that I'm made out of or you're made out of. Most of the stuff is not made out of quarks and electrons. If you take the budget of the universe, the energy budget of the universe, only about thirty percent of it is actually matter. Most of it's dark energy, which is pulling the universe apart. But of that slice that's matter, right, about eighty percent of that slice, something like twenty five percent of the whole universe is dark matter, this mysterious form of matter that's holding galaxies together and changing the shape of the universe. But we don't know what it is.
Right, it's totally different than our kind of matter.
That's right. Our matter is made out of atoms, which are made out of quarks and electrons. So we call that baryonic matter because it's made out of these particles that are familiar to us. And what we know is that dark matter is not made out of baryonic matter. It's not made out of quarks in some weird configuration that just makes it invisible and transparent.
And so we think maybe it's related to primordial black holes.
So one candidate for dark matter is primordial black holes, because what dark matter needs to be dark, and black holes are dark. Dark matter needs to be pretty stable because it's stuck around the whole lifetime of the universe, and black holes are pretty stable, right. They last for a very very long time, if not forever, and they're hard to spot, and so they're a good candidate for dark.
Mounds all this time. Dark matter could just be black holes.
It could just be black holes.
Yeah, I thought we like ruled that out.
Well, people have looked for it, you know, we'll talk about that. But it's a pretty compelling possibility. It was never the number one possibility. People were looking for a weird kind of particle that we call a WIMP, the weekly interacting massive particle. But you know, that particle has sort of had it to day and that's come and gone. We thought it was probably a WIMP. We looked for it, we didn't see it. And now we're like hunting around in the attic for other ideas of dark matter that might also explain it that we didn't look at so carefully the first time around. And now that the wimp idea has sort of lost it shine a little bit, we're like digging through the attic to find these other ideas and buff them all.
All right, So, maybe like dark matter is just a bunch of black holes floating around in space.
That's right. And they would have to be primordial black holes, not stellar black.
Hole because we know they've been around for a long time.
Yeah, because we know they've been around for a long time. And also we know a lot about how many quarks there were in the very early universe. Right, we know that dark matter is not made out of quarks because we know a lot about how many quarks there were, because we do these really careful calculations, and we see that if you had more quarks or less quarks, you get a different mixture of stuff in the universe, like more helium or more lithium or more hydrogen. And that's the kind of thing we can measure really really well. And then we can backpropagate and we say, all right, given that we know how much helium and lithium and nitrogen and neon there is in the universe, that means there was a certain density of quarks in the early universe. So for dark matter to have been around, then it can't have been made out of quarks. It had to be taken out of the equation before quarks were made, and that's why it would have to be primordial black holes to sort of like scoop all that energy in that matter out of the pie before you got around to make it.
Put it into these primordial black holes, and then wait until humans are confused about the whole thing.
Oh interesting, exactly, And so nobody's seen these things, right, primordial black holes still theoretical. Nobody has seen them, and we'll talk in a minute about how you could look for them.
See all right, so then what else do they do they explain?
Possibly, well, the other thing they might explain are these incredible black holes at the center of galaxies, you know, the Milky Way. Its very core is really hot and dense, and the stellar environment there is choked with gas and dust and activity. But at the very very core is a huge black hole. And that black hole is called Sagittarius A, and it has you know, the mass of millions of suns. It's enormous. It's like an incredible object.
And mystery because they're so big. There's sort of like no way for them to have come from stars almost right, Like it's like just to cramp together a billion stars that turn into black holes is kind of hard.
And it's a lot harder than you might imagine. You might think, well, doesn't that big black hole get really powerful and just suck stuff in? Isn't it sort of like a runaway process? Remember that we are not falling into the center of the galaxy for the same reason that the Earth is not plunging into the Sun and the Moon is not crashing under the Earth, and that's rotation, and you have angular momentum which keeps you from falling in. Even a really strong force of gravity cannot overcome angular momentum and suck stuff in. So a really strong black hole, it's not that easy for it to actually grow. It's mostly pull stuff in into its accretion disk to spin around it really fast, but to actually grow doesn't happen very quickly. So they do these studies where they say, can I make a milky way with this black hole in it? Let me seed it with a couple of little black holes and let it grow. And when they do those calculations, they don't get a big enough black hole. Like the black holes we get in our simulations are much smaller than the black holes we see in real life.
So is the idea then that maybe that black hole at the center of our galaxy was there at the beginning, like maybe it was there, yeah, beforem even matter formed around it. Maybe it was one of these huge primorial black holes, and that's how it started. It started off.
Big, exactly. You got to seed it with a big black hole, like maybe galaxies were formed around huge primordial black holes, which then gathered together dark matter and all sorts of normal matter around it, seeding that sort of structure. And if you start from a big enough black hole, then it's much easier to get to the kind of big, super massive black holes that we see at the centers of galaxies. And the other critical thing to understand is that these super massive black holes are not new. It's not like they've just formed. We see them because they're very easy to spot because they create intense radiation in the form quasars that we've talked about, some of the brightest things in the universe. We can see them from very far away, which means we see very far back in time, so we know that they were super massive black holes making quasars in the early universe. So not only are they huge, but they've been around a long time. So you know, that sort of smells like there's something else going on out there in terms of making black holes.
That's a wild idea because that would mean that galaxies almost formed because of primordial black holes. You know, like like galaxies form where they were because that's where the primordial black holes were. Yeah, you know, like they were the pioneers for galaxies.
Yeah, and it makes a lot of sense, right, The seeds of structure of the whole universe come from what happened in those first few moments, And if those first few moments triggered the formation of primordial black holes, then that sort of you know, made the decision, Like, once you create a primordial black hole, it's sort of a foregone conclusion that everything else is going to like gather around, and you're not going to start a whole new party when you already have a big one pumping away.
Oh so they almost like where they form determine the shape and the look of the universe.
Yeah. And the thing that I'll never stop being amazed by is that those formations come from random fluctuations, like quantum mechanical randomness in the very early universe, which means that like this randomness determined the structure of our universe. You run the same rules of the physics over and over again, you get a very different universe. I mean, you might still have black holes and galaxies, but you get galaxies in different places. Right, somebody's rolling a die out there and making different universes every time. It's sort of amazing every time. Every times. Yeah, you know, there's not that many places in the world where you can see the effects of quantum randomness. Mostly it's just averaged out. You know, there's quantum mechanics everywhere, but mostly it just sort of balances itself out.
It's like almost like where the evidence of quantum fluctuation.
Yes, exactly, if there were quantum fluctuations, there would be no structure at all. So we are all the products of quantum fluctuations. So thank you to quantum fluctuations for having made.
Us set the quantum physicists.
Made of quantum particles.
All right, well let's get into how why else we think they're there, and whether or not they're real, and whether we can maybe actually see or smell and touch a primordial black hole. But first, let's take another quick break.
When you pop a piece of cheese into your mouth, or enjoy a rich spoonful of Greek yogurt, you're probably not thinking about the environmental impact of each and every bite, But the people in the dairy industry are US. Dairy has set themselves some ambitious sustainability goals, including being greenhouse gas neutral by twenty to fifty. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. Take water, for example, most dairy farms reuse water up to four times the same water cools the milk, cleans equipment, washes the barn, and irrigates the crops. How is US dairy tackling greenhouse gases? Many farms use anaerobic diesters that turn the methane from maneuver into renewable energy that can power farms, towns, and electric cars. So the next time you grab a slice of pizza or lick an ice cream cone, know that dairy farmers and processors around the country are using the latest practices and innovations to provide the nutrient dense dairy products we love with less of an impact. Visit usdairy dot com slash sustainability to learn more.
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Right then, we're talking about primordial black holes, and you know, it sounds like maybe they could explain a lot of mysteries, like how the universe formed the way it did and where dark matter comes from. And so we think they're there because not just because of these series and because they could explain these things, but we're also kind of seeing them kind of in a way, or we're seeing clues that they might exist.
Yeah, we see lots of things that are easier to explain if primordial black holes exist, which is sort of a very indirect argument, but you know, the kind of thing you want to see if these things are real. And another piece of evidence is that we sort of see more black hole collisions than we expected. Remember, we turned on this incredible device a few years ago called Ligo, which looks for gravitational waves, so kind of shaking of space and time that only happens when incredibly massive objects orbit each other and then collide like black holes. And the thing to understand is when they turned this thing on and they made it powerful, they made it sensitive enough to see this kind of shaking of the universe, they didn't know how often the universe got shook. Like they built this device that could see these waves, but they didn't know if the waves were everywhere or just like once in a million years.
Right, It was sort of built to listening for black holes crashing into each other, but we had no idea how often that happened.
Yeah, And there were calculations all over the place. And the amazing thing is that, you know, they turned this thing on and they found one basically right away, Like they were still doing a lot of their calibrations and test run when they saw gold and gold and collision come in like the first weekend, it's like the best case scenario for science, you know.
So it's like it's happening more often than they expect it, Like, like you know, there's black holes crashing all over the place kind of.
Yeah, And what that means is that there are more black holes than they thought in the particular sort of mass range that they can see them. Like, they're good at seeing collisions of black holes that are like ten to one hundred times the mass of the Sun, and there are more of those than they think. Like, you can get black holes about the mass of the sun or five times the mass of the Sun, but to get black holes like fifty or one hundred times the mass of the Sun is not that easy, as we were saying before, because there aren't stars that big, and black holes have to merge to make them, and so we're seeing more of those than we would expect, which again suggests, hey, maybe these are primordial black.
Hey maybe the universe is littered with them. Yeah, maybe even in our own backyard. Actually, there could be one here in our solar system.
There could be one in our solar system. Now this is very speculative, but super fun. We did a podcast episode last year about planet nine, Like, when you look at the orbit of the outer planets, there's some weird things that we don't understand that are sort of suggestive of another gravitational body out there, something out there that's tugging on these things. It's making their orbits a little weird. And it's not conclusive at all, but it sort of makes more sense if you add one more planet.
Right.
The problem is we haven't seen that planet, like where is it? You know, even Pluto we can see. And so one super fun idea is that.
Maybe it's like it's invisible.
Maybe it's invisible, like we.
Can feel it. It's affecting the orbit of the other planets in us, but you can't see it. So maybe maybe it's a black hole.
Yeah, and maybe it's a small black hole. In this case, to have the right mass, it would have to be really small. I mean, it's still be pretty massive. But we're not talking mass of the Sun. We're talking about an object about the size of a tennis ball, and.
Like that's orbiting our Sun. It's like a black like our solar system. You're saying could have a tennis ball black hole orbiting around it, just like it has planets orbiting around it.
Yeah, wow, exactly. And a black hole that's small would still have enough gravitational power to change the orbits of the planet's enough to tweak them to make that visible from Earth. So if there were such a black hole, this is exactly what it would look like. That doesn't mean it's there, but it's.
Tantal right, right. And so the idea, I guess is that this black hole in our Solar system didn't form like after the Solar system. It almost predates the Solar system and predates you know, matter itself. Like it's maybe the universe is littered with these tennis balls black holes, and we just happened to like catch one in our solar system.
Yeah, maybe we should have called them like indigenous black holes because they were here before we got here, right, they were like, Hey, this is my solar system. What do you guys doing it sitting up camps, this colonizing my part of space.
It predates the atoms in the Sun.
Yeah, it predates the atoms in the Sun exactly. And so it could have been here and just fell into orbit around the Sun. It could have been captured, you know, it could be wandering the universe and then been captured. The zillion possibilities, but it's got stories to tell.
And yeah, it's seen the birth of our source system. Yeah, if it exists it.
Has embarrassing baby pictures about our son.
It knows you when you were small. All right, So then let's cover really quickly here whether or not these primordial holes are real. I mean, how we seen them? How could we see them? What are we doing to confirm their existence?
Well, we have not seen any evidence for their existence yet, which is disappointing.
Except maybe this planet nine, right, or you know, indirectly as a reason for the ones at the center of galaxy.
Yeah, we see things that would make more sense if primordial black holes existed, but there could also be other explanations. It's very indirect. What we'd like to do is see them sort of much more directly, see something which has to be a primordial black hole. And this one of the origins of this whole idea was Stephen Hawking thinking about black holes evaporating, and he realized that, you know, black holes might not live forever. They give off this radiation. But the key thing about Hawking radiation is that the bigger the black hole, the less it radiates. So a super huge black hole, anything bigger than like ten to the twelve kilograms, will take longer than the age of the universe to evaporate, so they basically live forever.
Right because they have so much stuff in them.
They have so much stuff in them. But as a black hole gets smaller, it has much less mass than it actually radiates more. And so if you're less mass, you radiate more, which means you lose mass, which means you radiate even more, which means you lose even more mass. And so black holes around like ten to ten or ten to the eleven kilograms, they can radiate away and actually disappear on the timescale of about a billion.
Years, which helps us because.
Well, wouldn't you like to see a black hole die?
Do not? If I have to wait a billion years.
Well, but we're fourteen billion years in, which means if black holes are living about a billion years, then they should be dying all the time. We should be looking around and seeing this happen.
So you're saying, we could see a black hole dying, or yeah, we see we see the like the sputtering, the last few gasps or what.
Well, it will not go out with a whimper. Remember, it evaporates more rapidly as it gets to lower mass, so the last few moments are very spectacular. That's when it's radiating even more than it has before. So they would go out in this big flash of light essentially really like it starts off very gradually and then it would blow all of its energy in the last moments, you know, in this runaway evaporation. It would be very spectacular.
Oh wow, like the last gasp of a black hole.
Yeah, and it would be very characteristic sort of radiation. And so we've looked for this, and we've sent our satellites out to look in space to see if we can see these kind of flashes. And you might expect to see them sort of like in the edge of the galaxy where it's otherwise dark, but we haven't seen any of them.
Like we know what kind of radiation they would give off.
Yeah, because black holes give off a very particular kind of radiation, this hawking radiation of a certain spectrum, so we would expect to see it indicates the sort of temperature of the black hole at the moment. Oh, I see, so it would look like nothing else I see.
So it is the idea then that you know, if the universe is littered with primoritial black holes, we should see a whole bunch of them dying all the time.
Yeah, that's exactly right. They were all born big bang. But if the last you know, billions of years, we've been around billions of years, and so we should see some of them fuzzing out of existence.
But so far we haven't seen. We haven't been seen these.
We have done and we've looked pretty carefully, and we haven't seen those. So that tells us that if there are primordial black holes sort of of very low mass, you know, less than a billion kilograms, then there aren't very many of us.
We can still have one the size of a tennis ball in our solar system, but maybe it's not common.
Yeah, and that to have smalls, that's right. And the small ones therefore cannot explain the dark matter in the universe. There's just not enough of them, if they do exist, there's not enough of the small mass ones to explain the dark matter. But you know, maybe there are heavier black holes. Maybe there's really big ones out there, so we have other ways to look for those.
Or maybe all the little ones already died or.
Something, Yeah, precisely, and so we could look around to see if there are heavier mass black holes, and we have other ways to do that, like, if these black holes exist, then we should see lensing effects. We should see them like passing in front of stars and galaxies and blocking the light from the more distorting the light from them.
Right, just like dark matter. Wouldn't that account for how dark matter does that?
Just like dark matter exactly, except dark matter so far we've thought it was more diffuse. We've only detected dark matter and like really big effects gravitational effects and big clumps of dark matter lensing background galaxies, for example. What we're looking for here is like micro lensing, like a really tiny spot of something passing in front of an object and distorting it, not a big diffuse cloud. If dark matter really is made of primordial black holes, it should be made of these tiny little spots that we can see these micro lensing.
Effects, because I guess you're talking about black holes now that are about the size of a plant, or like giant asteroids.
Yeah, giant asteroids or larger, anything larger than that, we should see these lensing effects. And if they're even larger, if they're like really super crazy massive, then they would have big effects on like the structure of the galaxy itself and the relationship between galaxies, Like if they were just like ginormous, like mind blowingly like billions of suns, then it would distort the whole shape of the universe and we would see that for sure. So we know they're not like ridonculously big. And we're pretty sure that there aren't really massive primordial black holes out there because we would see these micro lensing effects. So we've ruled out the very very light ones and the very very very heavy ones. Right, there's this interesting region sort of in the middle.
Well, the very very big ones might be like galaxies, right, that's where they might be.
Right, but we know the size of the black holes in the center of galaxies, and that certainly doesn't account for the dark matter.
All right, So we're looking for them, and how are we looking for them? I guess with telescopes, with radiotolscopes.
Well, another way to look for them is to see them destroying other stars. Like if you have this sort of intermediate class black hole, something like you know, ten of the fourteen ten to the seventeen kilograms, then they would occasionally like pass through a white dwarf or a neutron star and essentially destroy it. What, Yeah, because you.
Know yeah, I guess if you have a whole bunch of black holes floating around everywhere, it would be a little bit you would expect there to be a little bit of a chaos.
Right, Yeah, it would be disruptive, and so they would pass through and they would shatter these things. They might ignite fusion in a white dwarf like kick it up into actually burning again, and they could totally disrupt neutron stars. And we just don't see that happening. Like the population of white dwarfs and neutron stars, it looks as we expect, and so we don't see a big effect. We don't see, you know, something assassinating neutron stars out there.
We don't see a whole bunch of chaos weasels running around the galaxies.
That's right. But this part is very is hard, Like this is a hard measurement to do to find these things, to calculate how often you would see them. So there's sort of a lot of controversy in this middle region here. People are still really not sure how strong those limits.
Yeah, I mean, there wed have to be these black holes and they would have to run into other stuff, which in space is kind of hard.
Yeah, And another thing we can do is we can just look at our own sun, Like our sun is big enough that it would survive having a small black hole just like go into it. And they've done these awesome studies where they show that you could see it happen by looking at ripples on the surface of the sun, like sun quakes could be evidence for micro black holes entering the.
Sun like little like that would be incredible. Wow, we should get into that, Like what happens if a black hole goes into our sun? So it sounds a little disconcerting.
Well, if it's really big, then we're in trouble. But if it's small enough, it just sort of like causes literal waves on the surface of the Sun. The sun will settle back down and be okay. But you can definitely see that. So that's the kind of thing we're planning to do in the future to see if we can spot these things.
All right, Well, it sounds like the sounds like an idea that makes a lot of sense. It's definitely a cool idea. But maybe the jury's still have whether or not they're like, actually there.
The jury's definitely out. We don't know. We're looking, Yeah, we're looking. We don't know if these things are real. If they are real, they would explain a lot, But so far, you know that it's not looking good. Like the best models suggest that if you made primordial black holes, you should make them sort of at all masses. They're really small ones the really big ones, And we haven't seen them at the small masses or the really big ones, so that makes it a little more awkward. So now you have to play some clever game and come up with some reason why you would only make primordial black holes at a certain mass region. So it makes it less fun and sort of less pretty of an idea. But hey, it's still possible.
Yeah, well, yeah, I was getting kind of excited about this idea.
It's a primeval idea. It's primordial.
Yeah, I should check my primordial or just maybe all right, Well, I think once again this points thing to all the things we don't know about the universe. We don't know what happened at the Big Bang, and we don't know whether or not maybe there are still the remnants of before the Big Bang just hanging out with us, even in our solar system.
Absolutely, and it's tantalizing to think that those remnants could be here, and they could hold clues as to what happened in those first few moments. They could give us insights into how the universe was made. And if we measured the sort of spectrum of these black holes and discovered their masses, and only these were made, not those were made, it would really be like a window back in the first few moments of the universe. So I really do hope they do exist, because primordial is a cool word, and the idea is cool, and I hope that they have secrets in them that they will review.
Yeah, because you know, why not? Right?
Why not? Exactly? The Big Bang was so much fun? Let's do it again?
Why not? Yeah, let's hold off on that. We'll put a pin on that. All right. Well, we hope you enjoyed that discussion. 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. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact but the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. How is us dairy tackling greenhouse gases? Many farms use anaerow big digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last Sustainability to learn more.
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