 All right, welcome, everyone, to the May 2024 NASA Night Sky Network member webinar. We're hosting tonight's webinar from the Astronomical Society of the Pacific in San Francisco, California. And we're so excited to welcome our guest speaker, Dr. Patrick Bricey with his brief talk, no, his talk about the brief history of everything. It'll be our as usual. For our Zoom attendees, go ahead and make sure to set your chat drop down to everyone, not just hosts and panelists, so we can all talk with each other. And before I introduce Dr. Bricey, I just want to make a couple of quick announcements. We're going to try something new for the first time this month. We have an NSM conversation coming up, and it's for Night Sky Network members, and it's called Adding to the Toolkit Behind the Headlines with the Night Sky Network. So if you enjoy this webinar, please join us for this members-only. It's a meeting, so we will be able to see and talk with each other. That's on Tuesday, June 4th, at 5 p.m. Pacific Time. That's 8 p.m. Eastern, along with our friends at the Museum and Informal Educator Alliance. And Dr. Bricey here, who's, we're going to do a deep dive into some of the things that we've talked about tonight. So I'll throw a registration link in the chat in a few minutes. Go ahead. Thank you. Thank you. This is Brian Cruz with me. He's at the Astronomical Society of Pacific and San Francisco 2, and I'm Vivian White, your other host for this evening, and Kat will be back next month. I just want to let you know that we will not have a webinar for July, but we have a great one coming up on Mars for June, and I'll put some more information about that in in just a minute. Also, we have some office hours. If you have any questions about how to work the Night Sky Network with your club, if you have any thoughts, you're welcome to shoot us an email or on our regular email night sky info at astrosociety.org, or you can sign up for office hours, and I'll stick that in the chat as well. If you haven't already, Brian, you might be beating me too, all these. So I think that's it. Without further ado, I'll get started. Thank you so much, Brian and Patrick, for joining us. For those of you who are joining us on Zoom, make sure to find the chat window in the Q&A window on the bottom menu on the bottom edge of your Zoom screen. Those, the chat's great for talking with each other, but if you have questions specifically for the speaker tonight, go ahead and put that in the Q&A so we can keep up with those. So sometimes they'll get lost amid the chat. So if you have questions for our guest speaker, just put those in the Q&A window, not the chat window so we can see it. You can shoot us an email anytime again at nightskyinfo at astrosociety.org. And without further ado, tonight's night sky network speaker is Dr. Patrick Brycey. Speak with us tonight about a brief history of everything. Patrick Brycey is currently a James Author Postdoctoral Fellow at New York University, at least for the next few weeks when he will make the move down to Texas and join the Mustangs at the Southern Methodist University as Assistant Professor of Physics. Congratulations to that. Dr. Brycey received his PhD from the Department of Physics and Astronomy at Johns Hopkins University. His research focuses on a new way of mapping the distant universe, which can watch the earliest stars form, study how the universe evolves, and look for new physics behind the standard models. I also just found out that he plays the euphonium including at Tuba Christmas, which if you have not had the pleasure of a Tuba Christmas, you should find one near you this winter. He also enjoys hiking and science fiction novels. I want to introduce Dr. Brycey joining us this evening. Take it away. Thank you so much for joining us. All right. Thank you Vivian for the very kind introduction and for the invitation to come speak with you all this evening. While I get the screen share popped up, I will second the recommendation to go to a Tuba Christmas. If you've never heard 400 Tuba players playing Christmas music outside, then it's an experience you should have. But I am not here to talk about Tuba's tonight. Tonight I am here to talk about space and the topic that I have chosen to talk about is a brief history of everything. So to start with a little bit about me, I'm an astronomer, but the specific area of astronomy I work in is that I'm a cosmologist. And you might be familiar with that, but for those who don't know, cosmology is the professional skill or practice of no, wait, sorry, that's cosmetology. That's a totally different thing. Cosmology is in fact the branch of astronomy that deals with the origin and structure of the universe on the largest scales. So we're not necessarily interested primarily in individual stars or planets. We want to know where the whole thing came from and where it's going. You can think of cosmologists as something like astro historians in that our job is to try and understand and explain the history of the universe and how it got to where it is today. So tonight I have taken on the unenviable task of attempting to summarize 14 billion years of that history in 45 minutes or so. So I'm gonna see how that goes. Now, a history like that, there is only one place you can start it. So in the beginning, there was something. I don't know what it is and neither does anybody else. Because you see, we have this thing we call the Big Bang theory, supposedly our theory about the beginning of the universe. But I really don't like the name Big Bang theory. Not because it's kind of a silly name and not because of Sheldon's of any age, but because the theory we call the Big Bang theory, the set of mathematical laws and equations and data that we have to make up this theory, describes everything in the universe except the Big Bang. It tells us with exquisite prediction everything that happened after the beginning of the universe. But as far as the beginning of the universe itself, the so-called Big Bang theory doesn't actually say anything about it. Now, how did we end up in that situation? So let's go back 100 years or so to the turn of the 20th century and a pair of astronomers. One you've almost certainly heard of named Edwin Hubble. He's the guy we named a space telescope after. And one who you probably haven't heard of named Henrietta Swan Levitt, possibly because we are generally less good about recognizing the contributions of women to science. So around the time these two were working, this is a cartoon of what we thought the universe looked like. We have the earth orbiting the sun, and it's sitting in the middle of a cloud of stars that looks more or less the same in every direction. Maybe it's a little bit flat and pancake-shaped. And as far as we can tell, that's how the universe has always been, and that's how it always will be. But there were a few mysteries, and one that was big enough to earn the term the Great Debate, concerned these objects called spiral nebulae. Because weird, swirly thing, I guess, doesn't sound science enough. So these were images that these astronomers were taking through their telescopes. They were imaging on the photographic plates at the time, and nobody really knew what they were. And attempting to figure that out was complicated by the fact that when you're doing astronomy, it's very hard to tell the difference between something that's relatively small and close by, and something that's really big and far away. So what Henrietta LaSwan-Levitt did, though, is she figured out a trick for figuring out how far away certain things are in space. She did it by looking at a very specific kind of star called a Cepheid variable. Now, you don't necessarily need to remember that name, but the trick is about these stars is that they're constantly growing brighter and dimmer. Every few days, they get brighter, they get significantly brighter, and then fall back fainter again, and then get brighter again, and this constantly repeating cycle. And the cycle has a very regular period. It happens, takes about the same amount of time to get bright, get dim, and get bright again. Now, this period had been known about for a long time, but what Henrietta LaSwan-Levitt figured out is that the brightness of the star was extremely well correlated with that period. In other words, the longer it took a star to go from bright to faint to bright again, the brighter that star was. And what that means is that you know the physical intrinsic brightness of the star. And that means if you know how bright something is, and you know how far, and you know how bright it looks, you can figure out how far away it is just by measuring how much light you pick up from the star. Now, the reason why we're talking about all this is, as we go back to Edwin Hubble, Hubble found a bunch of these Cepheid variable stars in these so-called Spiral Nebulae, and he dutifully observed them for a period of time, tallied up their periods, how long it took them to change in brightness, and he figured out that these things were extremely far away. They were farther away than basically anything else that had been measured at the time. In fact, the nearest of the Spiral Nebulae, which we now call galaxies, the Andromeda Galaxy, is 24,000 million, billion, trillion, quadrillion, quintillion kilometers away. Now, normally, when giving a science talk, when you run into this kind of large number, try to make some analogy where like, if the Earth was the size of an egg, how far away would the galaxy be? But if the Earth was the size of an egg, the Andromeda Galaxy they were measuring the distance to is still 94 trillion kilometers away, which is still a distance that's far too big for the human brain to manage. And yet these things are enormous. If you've ever, if the Andromeda Galaxy was bright enough to see with the naked eye, it would be several times the size of the full moon. You could actually see the center of the Andromeda Galaxy with the naked eye, because even though it's so very far away, it is so big and bright. And there were, even then, dozens of these Spiral Nebulae, and now we know there are millions of other galaxies. So in this brief span of time, we've gone from this nice cozy little image of the universe where it's big, but it's not that unmanageably big. Well, now we've made the universe a lot bigger. We've taken the Earth from the center of it, moved it to the outskirts, and now this blob of stars that we live in the middle of is just one of millions and millions of other similarly sized galaxies. Astronomy is always a good line of work for telling you you are insignificant in 10-story high flaming letters. Now, this was a big enough discovery on its own, settling this so-called great debate, but where does the Big Bang theory come in? Well, Hubble did realize something else when he was looking at all of these stars and measuring all of these distances. He realized that all of the galaxies he could see, with the exception of the nearest ones, are actually moving away from us. And the farther away you look, the faster those galaxies are moving. Now, you might think that, okay, maybe there was some explosion or something in the Milky Way that threw everything off into space, or maybe the other galaxies just think humans smell really bad or something, but by doing a little bit of trigonometry, you can figure out that if we were sitting in any other galaxy, it would also look like you were the center. It would also look like everything else in the universe was moving away from you. In fact, it's the entire universe itself that's expanding. Everything is moving away from everything else. So, just to ramp up the insignificance a little more, all of these massive incomprehensibly large and incomparably distant systems are now moving even farther away. And also, there's even less reason to think you're special because it would look exactly the same from anywhere else in the universe. But where this expansion concept gets really spicy is, okay, everything's moving away. What happens if we look in reverse? What happens if we take this pattern and extrapolate it back in time? Well, if everything's moving away from everything else, then eventually, everything ends up all crammed into one spot. And so, something it appears in the distant past happened that threw all of the matter in the universe away from itself with such force that it is still moving today tens of billions of years later. And that event is what we call the Big Bang. I guess because the Lambda CDM cosmological model would be too clunky to name sitcoms after. So, but the nature of that event remains completely unclear. Of course, there are millions of theories, but no hard data on exactly what it is. So, if I want to give you a detailed history of everything, we have to in fact start shortly after the beginning when the universe looked more or less like this. Except for by this, imagine it's not just white, but it's actually X-ray, ultraviolet, gamma-ray, hot. Now, you might think, you know, I've seen pictures of the universe. I've looked through telescopes. The universe doesn't look like a blank white void. The universe has all kinds of structure and all those galaxies we were just talking about. But at this point, none of that has formed yet. And the entire universe is basically one big cloud of extremely hot hydrogen. So hot, in fact, that the protons and the electrons can't even cool down enough to form atoms. The entire universe is one big, blindingly hot plasma cloud that looks basically the same everywhere you go, but it only looks basically the same. So let's turn up the contrast on this image a little bit. And what you start to see is you start to see patterns emerging. In this picture, red places are places where the gas in the universe was a little bit brighter and blue places blue spots are places where it was a little bit cooler and fainter. And this isn't a computer simulation or a PowerPoint graphic or anything like that. This is an actual image of what the universe looked like when it was only 100,000 years or so old. Now, if you've not spent a lot of time around astronomers, you might be asking, how can you possibly know that? How can I take a picture of the universe if it's 14 billion years old now? How can I take a picture of it when it was thousands of times younger? And if you haven't spent a lot of time around telescopes, you might know that every telescope we build is secretly a time machine. And that is because light, the thing we're using to observe everything in the universe, travels at a constant speed, which we have imaginatively named the speed of light, which is about 300,000 kilometers a second or 186,000 miles per second for what I imagine is a mainly American audience. And that means that since light doesn't travel instantaneously, whenever you look at something, you're not seeing it as it is now, you're seeing it as it is when the light was emitted. So the moon, for example, it takes light about 1.3 seconds to get from Earth to the moon. So when you look at the moon, you're not seeing it as it is now, you're seeing it as it is 1.3 seconds ago. We've actually positioned, during the Apollo missions, we actually positioned big mirrors on the moon, where we can shine powerful lasers from Earth towards the moon and pick up the reflection 2.6 seconds later. It's actually how we measured the distance to the moon with high precision. It takes light about eight minutes to get Earth from the sun. So when you look at the sun, looking eight minutes back in time. A nearby star, like Alpha Centauri, now we're talking years. It takes like four years to get from Alpha Centauri to Earth, which is in fact, where we get the term light year. It's the distance light travels in a year. Alpha Centauri is four light years away. And when you start getting to the incomprehensible distances of the spiral nebulae, the distances to even the nearest galaxies, now we're talking light taking 2.5 million years to get there. So now we're looking at light that was emitted before the human species existed. So a specific telescope called the Plunk Telescope, built primarily by the European Space Agency, looked out into space and looked behind all the stars and all the planets and all the galaxies. And they found this light emitted. Sorry, I seem to have dropped off Zoom for a second there. Yeah, you did. How long have I been gone? The last thing you said was you're looking at the Plunk satellite and looking beyond all the other galaxies that we could see in the Hubble Deep Field. Got it. Sorry about that. I have no idea why Zoom. Anyway, the joys of digital technology. Anyway, you look beyond all the stars and galaxies and you see these patterns. You see this light, which is actually in the microwave frequency. And we see that there are these regions that are a tiny bit brighter and a tiny bit fainter than others. And since this light is coming from farther away than anything else we can see in the universe, this must be the oldest light in the universe. And is in fact the light given off by that explosion of the Big Bang. Now, when I say patches of this are a little bit brighter or a little bit fainter, I mean very slightly different. We're talking one part in 10,000. You wouldn't get excited if you went to a grocery, you know, went to a clothes store and there was a sale advertising .001% off. The universe is still basically the same everywhere you look. But there are these very tiny differences. And as the universe ages, these differences start to become more significant. So we have the Big Bang where something throws all of the matter in the universe in all directions at once in one hot cloud of hydrogen. And as it goes, the entire universe cools off and gets darker and fainter until now the whole universe basically looks like this. Universe is basically a now a pitch black, almost uniform cloud of hydrogen, still extremely boring. Not at all like what we're used to seeing. Astronomers, being very creative again with our naming, like to call this age of darkness, the dark ages. So you wouldn't be able to see anything with your naked human eyes, but if you could see what the gas was doing at this time, you would see something very special happening. Because you see these places that are a little bit colder, those are areas of the universe where there is just slightly more stuff than there is in other places. And these areas that are red are places where there's slightly less stuff. Now, from as far back as Isaac Newton, we know that matter creates gravity. Gravity pulls things together. And the more matter you have, the more gravity you have. So what happens is that these areas where there's just slightly more stuff, slightly more gas, have slightly more gravity and they start to pull in the surrounding material. And now they have even more mass, so they have even more gravity, so they pull in even more material. And so what you're seeing here in this video is these purple and white regions are those over densities, the places where the gravity is stronger and they're accumulating more and more material. And the red areas are the voids. Those are those under dense regions which are slowly being emptied out. Now this is a computer simulation, obviously. This is the Dark Ages. We can't see this with our own eyes. But what we can see is that pattern in the universe's baby picture I was showing before gradually evolves into this web-like pattern of filaments and clusters that, again, with the creativity, we call the cosmic web. And you have to run a simulation to see the whole process take shape. But this pattern isn't just a theory. We can actually see it through our telescopes. So what you're looking at here is not an image from a project called the Sloan Digital Sky Survey. This is a map where every point of color in this image is the position, is the three-dimensional position of a galaxy. Now this is a good time to go back to that, all of that insignificant stuff. These galaxies are incomprehensibly large. Now resumed out onto scales where they're smaller than a pixel. But if you look at this map of galaxies, you see this same web-like pattern, the same pattern of filaments and voids. And that is this cosmic web. That is the result of the gravitational evolution of these teeny tiny fluctuations in the early universe down through billions of years, accumulating more and more material under their own gravity until the densest parts are able to turn into galaxies. Now just to clarify a couple of things people usually wonder about with this picture. The image is shaped like this because we're sitting down here surveying the sky with telescopes. And the disk of the Milky Way itself blocks our ability to look on this plot to the left or right. So we're able to map kind of a cone looking out into space. And then this line isn't any kind of physical barrier at the edge of the universe or anything. This is just the farthest distance this particular telescope is able to see. And we have since been working on even bigger and more detailed maps. There's a project called DESI, the Dark Energy Spectroscopic Instrument, which is going to observe 10 or 100 times more galaxies and look farther away and observe this cosmic web in greater detail. But that process that took us from the early universe to the cosmic web, that process of gravitational collapse doesn't stop here because nothing in physics, in real physics, is ever perfect. The material doesn't just shoot down into a point that collapse isn't perfect. So the gas ends up a bit spread out into these galaxy shapes. But if we zoom in to those galaxies further, we can see that even inside the galaxies, that process of gravitation collapse hasn't stopped. So now we're looking at a picture of a nebula taken by the one of many gorgeous pictures taken by the James Webb Space Telescope. And what we're seeing here is a cloud of gas and dust inside the Milky Way. It's a part of the Milky Way that is slightly denser and therefore has slightly more gravity than everything else in the Milky Way. Now we can run another computer simulation of if we take a cloud of gas like this and just let it exist for a while. Once again, we see these brighter areas are places where the denser areas of the cloud are pulling in more material and undergoing runaway collapse and becoming more and more denser. It's the exact same process happening inside the Milky Way that was happening in the universe as a whole, the same physics on millions of times different spatial scales. But here at this zoomed in level, you see something very special start to happen. You can hopefully see what look like tiny little sparks coming off of the densest filaments in this computer simulation. Now what's happening there is that as this gravitational collapse proceeds, as this gas these gas pockets pull more and more material down onto themselves, they actually become dense enough that the hydrogen atoms that are the vast majority of the gas get squeezed together so hard they turn into helium atoms. I've drawn two hydrogens turning into a helium you actually need four if you want to get technical. But of course if you want to get technical the process gets almost arbitrarily complicated. But when you combine hydrogen atoms to make helium, well that's something we humans have figured out how to do on earth. We get nuclear explosions. That process of fusing hydrogen into helium releases quite a lot of energy, at least as far as atoms are concerned. This is what we call nuclear fusion. It's a potentially has all sorts of potential as a future source of power. But right now the biggest use for we have is making the biggest explosions we are capable of making. This is why the largest nuclear weapons are called hydrogen bombs because they're powered by this process of turning hydrogen into helium. So on earth we can harness fusion to make bombs. In space, what happens is the energy from all of that fusion produces a lot of heat that eventually pushes back against that gravitational collapse, pushes back against that force and stops this process of collapse that has been ongoing since the beginning of time. And the result of that is what we call a star. A star is basically a continuous nuclear explosion happening out in space. And the power of that nuclear reaction is both what holds the star up, keeping it in a tenuous equilibrium, and what gives stars like our sun the heat and light that we see. So this was a computer simulation, but these nebulas, a lot of these nebulas that we take pictures of with things like Hubble and James Webb are places where brand new stars are being born. So several of the brightest stars in this image are new stars that have formed from collapsing dense pockets of this cloud of gas, which in turn formed from collapsing dense pocket of the Milky Way, which in turn formed from a collapsing dense pocket of the universe, until finally this process of hydrogen fusion stops that collapse. Now this doesn't just give us the light from the stars, but this process of nuclear fusion from these stars is actually what gives us basically everything in the universe that isn't hydrogen. Hydrogen and helium were formed a little bit during the Big Bang. There's some complicated stuff that formed some of the smaller elements, but an awful lot of other elements are formed either in the cores of stars or in the tremendous explosions that happen when those stars die and blast all the new material they've made back out into the universe to recollapse into clouds of gas like this and form the process all over again. But once again, gravity is not quite perfect. Everything doesn't all of the material around these stars doesn't quite manage to shump down perfectly onto the central mass. So if we zoom in very far on some of these images here, and this is continuing to be actual James Webb image imagery of this particular nebula, we see that some of these newborn stars this kind of bright spot here is one of these brand spanking new stars has this kind of dark fuzzy stuff around it. And what that is is once again the leftover material, the stuff that was caught in the gravity of the star but didn't quite manage to get sucked down perfectly onto the star itself. Now you might be able to guess what that is when I tell you that we have named it a protoplanetary disk, because once again bad with names running theme insignificance and being bad with names. And it's called a protoplanetary disk because just like every other process I've described in this talk, areas of it that are more dense will pull in the surrounding bits of this fuzzy haze. And what you get from that process is planets, big planets, small planets, planets of all shapes and sizes, gaseous, rocky, icy depending on how far away the star or when they formed. And in at least one solar system, one of those planets was in exactly the right conditions to have liquid water and eventually to evolve life. And eventually TV sitcoms about cosmological models. And so we can draw just from this fairly simple process of gravitational collapse, we can draw a direct line from the very early universe all the way down to the present day. And it was actually to my mind one of the most beautiful things in modern astronomy because this fairly simple physical model predicts so much of what we see in the universe today. But with my last 15 minutes or so, I want to talk about a little bit, you know, this is a remarkably successful theory in describing what we observe in the universe. But there are still aspects of it we don't understand. So I want to spend the rest of my talk talking a little bit about aspects of this process we don't know. And first of all, is I showed these computer simulations where you take tiny differences in density in the beginning of the universe and evolve them through to get the cosmic web that matches our maps of galaxies very closely. But I if the universe was actually a cloud of just hydrogen with a little bit of helium, these patterns don't actually come out quite right if you try to run these simulations if you try to run these calculations. And so this graph, I've covered up the y axis, the axis level because the actual math going on here is a little bit complicated, a little bit complicated. But it's basically measuring how many blobs there are, either in this simulation of the cosmic web, or in actual observations, versus how big they are. So actually backwards, we have smaller blobs, we have bigger blobs we have bigger blobs over here and smaller blobs over here. If you're fluent in math, we've taken a Fourier transform. If you're not fluent in math, the important thing is we measure the cosmic web, we do some math on it. And for real galaxies, we get these red points. And if we try to run our model, we try to run our cosmological model with just hydrogen, we get this blue line. Now, whenever physicists make a graph like this where they're comparing a model and data, usually you're looking for the model to go through the data points. You probably don't need a PhD in statistics to be able to tell that this blue line does not look very much like these data points. And that suggests that something is missing, something in this gravitational process is missing. And furthermore, if we look at the galaxies themselves, we can measure how fast they're spinning. We know the galaxies are held together by the gravitational force, which collapse them in the first place. We know about how much matter they have in them, but they're spinning too fast for that. If they're the only matter in these galaxies, was the stars and planets and nebulas, these galaxies would be flying apart. So just like with these large scale measurements, we have these small scale measurements that also need more matter than we can see with our telescopes, they need more gravity. So what is causing this? Well, we can't see it. So it must be dark. But it has gravity and otherwise acts like regular matter. So we're going to call it dark matter. Now, there are a million theories for what the dark matter could be far more than I have time to get into now. But there's no good way right now to tell which of these is correct. There's no good way to know what this dark matter actually is, only that there has to be a lot of it. In order to make both the small scale and large scale gravity situations match up, there needs to be about five times more dark matter in the universe than regular matter. And that's only a small part of the problem, because gravity still doesn't quite work right. Because when I look at all those galaxies that are expanding away from us that Hubble saw, well, we have this model I described where the Big Bang threw everything in the universe out away from each other. But all of these things have mass, they have gravity, that's what's been driving this whole process of formation of everything that I've been talking about. So we know gravity tends to pull things back together. I throw a baseball up into the air, it falls back down to the earth because the earth and the baseball both have mass and they're both pulling each other together by gravity. But what we see when we look at those galaxies is they're actually moving apart faster and faster. It'll be like if you threw that baseball and it just started shooting off into space faster and faster. And once again, we can write down mathematical descriptions of this process, but we still don't know exactly what it is. Clearly whatever's causing it is still dark because we still can't see it. And it's not matter. So the name we have for stuff that's not matter is energy. So we call it dark energy. Now, I said dark matter was only a small part of the problem. There needs to be about three times more dark energy than even the dark matter. This tiny wedge here, about 5% of the material in the universe, that's you. That's you, that's the sun, that's the planet, that's everything you see in the vast majority of telescope images is only 5% of the universe. And we have ideas for what the other 95% is, but we don't actually know what the correct idea is. And this is probably one of the biggest mysteries in physics today. And finally, I want to talk about the challenge that I actually work on because you've all sat here so patiently. So your reward is to get to hear me babble about my day job for a few minutes. So I mentioned when I was showing this map of the universe, remember this is the image where we're sitting down here looking out of the Milky Way and every pixel is the position of a galaxy. Well, I said this line is here because that's how the farthest objects these telescopes can see. But they can't see all the way to the beginning of the universe. If I make a map of what we can actually see, where remember looking farther away means looking back in time, we have a really detailed picture of the universe when it was a baby. And we have really detailed pictures of the universe now, but there's a gap here. A gap spanning about 2 billion years of cosmic history that we can't see with our current telescopes very well. Or even if we can see it, we can look much farther than this with sensitive telescopes like the James Webb telescope. But we can't do this kind of large volume survey where we can pick out this cosmic web that's telling us about dark matter and dark energy. And there's a lot of important stuff that happened here. This is the time when the first galaxies formed and the first stars formed. This is that entire early process of gravitational collapse to form the cosmic web. And so the thing I do in my day today is work on finding a way to push out further into this gap while still being able to map these huge volume of space you need to see the cosmic web. So what I actually do is a trick called intensity mapping. So on the left panel here, we have a kind of toy simulation of galaxies in the cosmic web. Think of it as a zoomed in patch of this map where every gray dot in this picture is the location of a galaxy. Now, if I took our best telescopes and spent literally years doing nothing else but mapping this chunk of space, I could see the galaxies that I've marked in red, which corresponds to about 1% of the galaxies in the universe. And they're the brightest 1% of galaxies. So this is a little bit like aliens trying to understand human athletics just by looking at Michael Phelps and Usain Bolt. If something's in the 99th percentile of brightness, it's probably weird. But all these other galaxies still exist. They still emit light. That light still streams through space and hits our telescopes. It's just the noise in the telescope is too much to be able to say for certain the locations of these individual galaxies. But to me, as I said way back at the beginning, I'm a cosmologist. I don't necessarily care in my day-to-day work about any individual galaxy. I care about these large questions. I care about the cosmic web. And so I don't actually need to find every individual galaxy. I can instead make this kind of smeared out picture, like we see on the right, where all I've done is I basically taken these galaxies and made a low-resolution picture of them. You can see these kind of orange blobs trace the same structures. They trace the same cosmic web. But what I'm measuring is the total emission from all of these galaxies rather than having to pick out each of them one by one. And what this means in practice is that we could spend lots of time on a big telescope and only see some of the galaxies. Or we could spend less time on a less big and most importantly much cheaper telescope and still get most of the information we're looking for. So I'm on several different projects attempting to make this kind of image. The one I want to mention that I spend the most time on is a project called COMAP, which is a radio telescope built out in the desert near Death Valley in Southern California. So what can we do with this? Well, we survey the sky. They have about four square degrees of sky. And we just zoom back and forth over it and make this aggregate image picture. And we can do the exact same statistics on this that we would do on our normal simulations to study the cosmic web and study dark matter and dark energy and try to learn about the universe. The other trick we can do on the smaller scale physics I talked about is the name COMAP stands for the carbon monoxide mapping array project. And the reason for carbon monoxide is that these dense clouds of gas where eventually hydrogen fuses together to form helium. Well, in the less dense corners of that, carbon and oxygen atoms floating out in space can form carbon monoxide molecules. And you need relatively dense gas to do this. You need to be fairly far along the process of gravitational collapse to form carbon monoxide. And so if we can measure how much carbon monoxide there is in the universe, we can measure how much dense gas there is and how many stars are being born. And because we're looking farther back in time than is possible with normal telescopes, we can watch some of the earliest stars and galaxies in the universe being born. Now, the reason why we can do that and the reason why we use carbon monoxide and this big radio telescope is that carbon monoxide molecules give off a specific set of radio frequencies that are relatively bright and easy to observe. So by building a radio telescope and tuning it to this very specific frequency of carbon monoxide, we can measure effectively if the three-dimensional pattern of these blobs tells you about the large-scale structure of the universe, the brightness of these blobs in that carbon monoxide radio frequency tells you how many stars are being born. So we can take this process of cosmic evolution from the large-scale cosmic web down to star formation, and we can observe all of it with this one telescope with a much smaller budget than you would need to do this with more traditional observations. And we are actually putting out the second data release from this telescope in a few weeks, which is very exciting. I can't talk about what's in it yet though, unfortunately. So to close, we have followed the gravitational evolution of the universe from its very early stages in these tiny, tiny density distributions down through the dark ages and the cosmic web down to the formation of individual galaxies, nebulas, stars, and their protoplanetary disks, and finally planets like the one we live on, all driven by the same process of gravitational evolution. And so the takeaway from this whole talk is that you might have heard the statement that, you know, if you give me an infinite number of monkeys with typewriters clacking away, eventually they'll produce the complete works of William Shakespeare just through complete randomness. Well, by studying cosmology, we can say definitively that if you take a big enough cloud of hydrogen gas and you let it sit for a long enough time, you can make galaxies, stars, planets, William Shakespeare, his complete works, and everything else you see around us today. And that is a brief history of everything. Thank you very much for listening. Happy to take questions. Dr. Breisey, that was wonderful. I know you couldn't hear us all laughing, but we were definitely enjoying it a lot. Thank you so much. That was fabulous. I really enjoyed you taking us through with a lot of humor and really good analogies. I think we have some great questions coming up, so I want to share some of those. Let's see. Bob asked one that I get all the time when I'm doing outreach. Do most cosmologists believe that the universe is infinite or finite? And how do you define that? That is a very good question. So I'll start with the easy direction because you can ask if the universe is infinite in space or infinite in time. And most cosmologists believe that we have this model where, if you run it back in time, everything starts out at one point. So there is a point we can define as the beginning of the universe, a finite time in the past. Now, as for whether the universe is spatially infinite, I can't necessarily speak for all cosmologists, but I think the most honest answer I can give is we don't know. Because we have this problem that all of the stuff we observe with is either light or travels at the speed of light. And that means if the universe is 14 billion years old, the farthest we can look is 14 billion light years away before you're basically looking at the Big Bang. You're looking at that temporal finite time. And that's hiding your ability to say anything about what the universe looks like farther away. So the universe could have outpassed what the laws of physics permit us to see. It could have something resembling a boundary. It could extend forever. And there are, of course, people who theorize about it. But as far as the evidence goes, we don't know. Oh, good. That's what I tell them. I don't know. Oh, that's wonderful. Thank you so much. There are questions coming in faster than I can even read them. But some really good ones. Let's see. What have we got here? You talked about the dark matter. Oh, there was a question about in the beginning, you put up a really long name for the Big Bang. Or maybe it was ACDM, I believe. Can you tell us what those mean, what those letters stand for? Yeah, the cosmological model, thanks. It is the Lambda CDM cosmological model, which is the technical term for the body of mathematics that we colloquially refer to as the Big Bang theory. And what it refers to is the DM is dark matter. The C is cold, which is basically a way of saying at the beginning of the universe, we don't think the dark matter was moving around that much. The cosmic web pattern kind of looks different if the dark matter is moving around versus if it's not. And Lambda is the Greek letter used in Einstein's theory of relativity to represent one of the possible things that dark energy could be. So basically, what the Lambda CDM means in plain speaking terms is we have a universe made primarily of Lambda, which is dark energy, and cold dark matter, and everything else is just basically a small correction we can ignore. Like you're ignoring air resistance in high school physics. That's great. Okay, there's a few go ponies. Congratulations on your new position. There's a question about the COMAP project they're working on. It says it aims to trace the spatial distribution of star-forming galaxies at the epoch of reionization. Can you tell us what the epoch of reionization is and when it happened? Yes, I can. I see somebody has maybe been googling. And maybe you'll take your slides to show it. Oh, you might need them. Go ahead. I don't need the slides to show it. If you have something to show, go for it. But I guess I'll just... I think it's easier to show here. The epoch of reionization is something that happens in this kind of in-between range in this time where we can, you know, pick out a few individual galaxies with things like James Webb but can't make these kind of large-scale maps. Basically what happens is I mentioned early on that the very early universe was so hot that protons and electrons couldn't get close enough to form atoms. Eventually, the universe cools off enough that they form atoms. They form hydrogen atoms. And so the vast majority, for most of the Dark Ages, the vast majority of the gas is in the form of neutral hydrogen, protons and electrons. But then when the first stars form, the light from those stars is strong enough to knock the electrons back off of the hydrogen atoms. And so today, what we call the intergalactic medium, the leftover gas between all the galaxies, is basically entirely ionized. Again, it's ions, it's protons and electrons, not hydrogen atoms. So reionization is this kind of poorly understood process that happens somewhere in here where the entire universe goes from basically all neutral hydrogen to basically all ionized hydrogen. And, you know, it's kind of the last time the whole the whole state of the universe changed at once. Sometimes we call it a phase transition, like when a, you know, water all turns at once into an ice cube. There's some commonalities in the math. Very cool. Question about what carbon monoxide detection says about the dark energy and matter there. You said you were looking for carbon monoxide and there was just what does it tell you about it? Yeah, that's a good question. So the carbon monoxide itself isn't necessarily telling us about the dark matter and dark energy, because basically, when you start getting into the math of physics, what like spatial scale something operates on. So like the gas physics behind the carbon monoxide molecules is all happening on small enough scales that ordinary matter is basically dominating it. But since that carbon monoxide exists inside galaxies, it lets us measure the positions of those galaxies, or the smeared out positions thereof. And we do this, this statistic is called a power spectrum. This measurement of the number of blobs versus the size of the blobs. We can basically, because these red points here taken from the positions of individual nearby galaxies, we can make that same measurement on these smeared out positions of the carbon monoxide emitting galaxies. And we can, you know, fit a line, fit the model to it, you know, ask how much dark energy there is. And depending on what dark energy is, some theories of dark energy, different theories have different predictions for how many blobs there are at different times. Basically, this is, I think, the least mathematical way I can express that. And there are theories that we can tell apart if we have this map out here that we can't tell apart back here. My PhD thesis was basically about doing math on these blobs to compare it to models. Very cool. Maybe in kind of a related question, back to that picture of the web, cosmic web, Bill asks what kind of matter makes up this web? What is that? Is that dark energy? Is it dark matter? What are we looking at there? So what we're looking at specifically, the things we see are galaxies. We're seeing the light from physical matter. I think at the wavelength here, we're actually seeing the starlight. Like, I think we're seeing, I think for this map, we're seeing the same kinds of things, the same kind of light you see in the optical image of a galaxy, just zoomed way out. But the gravitational dynamics, the forces that are putting the galaxies in these places is driven by the dark matter under our model. It's the gravity of the dark matter that's pulling the galaxies together. Dark energy doesn't seem to cluster very much. Whatever it is, it ends up looking basically the same everywhere, whereas dark matter has gravity. And if you have a little more dark matter, it pulls more dark matter together. So kind of the information we have comes from normal matter, the shapes come from dark matter, and how quickly those shapes are changing is driven by the dark energy. And we measure all of those things to try and figure out what these things are. That makes sense. Well, you've been invited to Tuba Christmases all over the country, probably all over the world. I'm probably going to be at the one in Dallas this year. Right, exactly. If you're in Dallas, you should check it out. Darian's asking about when these comap radio telescope reports are going to be available. We're so excited. That was a real cliffhanger you're leaving us with there. Yeah, so we have our, we released what we call early science back in 2021, actually, if you dig around. I think they're in an open access journal. So those were, we call upper limits. We have noise in this picture. This is like an image without any noise. If you take a real image, it's very noisy. And so the kind of, you know, first thing we did after we turned the telescope on and made sure it's working, we hadn't seen anything, but we just had noise. So if you want to read more about it, and you can hack the technical papers, they're out there. And in the next month or so, I think is what I can say about the next set of results coming out. Particularly on the journal, you knew a presentation somewhere? Yeah, so there's actually, this whole concept is called line intensity mapping, and there's actually an annual conference on it, which is happening in Illinois in a few weeks that we're hoping to present at, and then they're going to be published in astronomy and astrophysics, or they're going to be submitted to astronomy and astrophysics, I believe. But you know, you're working with a, this picture is actually some of the collaboration of people working on it. So when you're putting out results, you basically need everyone to sign off on exactly what you're saying. So you can't quite talk about what's in them until everybody has had their chance to make sure they agree. When I take it personally, that's the beauty of science, it's getting everybody to agree on one thing that's wonderful. There's one that's taller than everybody else's me. Oh, look at that! You can never tell when you're talking to somebody on Zoom. I usually imagine people much taller than they really are, but I don't think that's the case here. That's great. All right, I just want to thank you so, so much for getting towards the top of the hour, and I want to respect your time. Thank you so much for joining us. It has been a real joy, a pleasure listening to you. It was fun and funny and interesting. There are a lot of comments in here about, wow, that's the best I've ever heard that explained. Thank you so much. I want to invite all of you to join us on June 27th. We're going to have another webinar here. It's Perseverance, Three Years of Exploring Mars with Dr. Kim Steadman. I'm excited for that. I just put the link in the chat. It's right here on YouTube. You can catch us, and we'll have a follow-up to this if you are joining us on the Night Sky Network. Brian has put that link in the chat as well. We'll do a little follow-up session on Tuesday, June 4th, and that's an hour earlier than these, and it'll be a meeting, not a webinar, so we'll be able to talk with each other. Thanks for all the wonderful questions, and thank you again, Dr. Bryce. This has been a real pleasure. Yeah, thank you for having me. It's always fun. Take care, everybody. Keep looking up. We'll see you next month.