 It feels like a new camp. Testing. Testing. Testing. Testing. Testing. Testing. I think it's good. You guys are going to make me talk like very into the mic. Did that make sense? Yeah. I'll be flipping you off. It's okay. Hello everyone. Welcome to Astronauts App. So the trivia sheets and golf pencils. So if you want to participate in trivia, see Sam to get a trivia sheet. Thank you. Thank you. Thank you. Okay, the trivia sheet from Sam. If you want to play trivia, we're going to get started. Good. My name is Megan. Realizing I've never introduced myself when I start these events ever until today. And you're at astro on top. Other astro on top questions. I'm going to go through all 10 questions and leave each one up on the screen for 30 seconds a piece. After I go through all 10 questions, I'm going to go back to the beginning each question over again, but only for 15 seconds. So you'll get two chances to write down your answer. After trivia, we'll have you turn in your trivia sheets to Sam, who you got the trivia sheets from and any other grad student that helps me. That's up here at the front. Our speaker come give his talk. Our first speaker tonight is going to be John Franklin Crenshaw, inflation, quantum foam, and multiverse. My name is JF. After JF speaks, we are going to announce the trivia answers and winners and then bring on our final speaker of the evening who is going to be Tom Wag. He's going to be talking to us about the chicken little LSST's impact on near-earth asteroid discovery. And then after that, if you won trivia, you can get your prize. Okay, everybody get it. With trivia, once again, you'll have 30 seconds a piece for this first round to write down your answer. I felt like it took so much longer this time than normal. We're going to start today though. Thank you very much. Thank you very much. Before you begin your talk, let's just stop for you to grab a mic. Okay, it sounds... It sounded a little, like, teeny bit, so... Yeah. I was trying to say, this was... Or is this one something else? This one might be a little... Yeah, I like this one. What year grab stupid, are you? Tell me. Okay. Yeah. Yeah. Okay. Okay. Okay. Wow, thank you. That's fun. I didn't know what that was. Can I get in here and change the slides? Absolutely not. Am I out of here? Okay. You will need this. Are you ready? Turn your trivia sheets into Sam so as we will not accept your trivia sheets without your golf pencils. And then I will introduce the first speaker. I forgot the little trench. I'm actually not ready yet. My lord. I love telling everybody to give Sam stuff and then standing way back here. I have never done that before, but I can give you time keys if you want. I'm not sure I'm supposed to take it. It really doesn't work. 20 to 30 minutes. You have a solid, like, 10 minute buffer. I bet I didn't get that. And honestly, if you go over 30 minutes, I'm not gonna stop you, so... Yeah, when you see Tom fall asleep, you're probably at 30 minutes. I don't know. I wasn't paying attention. Okay. I was gonna do it with no one else, but I was like... They beat you too. There might be another dog model too. That's what it tells me. Okay. Are you ready? Okay. Okay. Thank you so much for turning in your trivia sheets. We will get those graded and then tell you the answers in the intermission. We're going to introduce our first speaker of the evening. And the microphones are working, right? Good. Okay. The first speaker tonight is John Franklin Crenshaw, otherwise known as JF. He is a fourth-year graduate student in the University of Washington's Physics Department. However, his advisor is housed in the Astronomy Department. So he is a bona fide astrophysicist. And JF's study is mostly cosmology, which is the study of the universe, and I will let him explain everything else about that. So, JF. We'll try not to trip on this board. Oh, yeah. So, as she said, I'm John Franklin. I am a cosmologist at the University of Washington. There we go. And what that means is, as a cosmologist, I get to study the universe itself. Its origins, its evolution, how we got to all of the big, beautiful galaxies we see today. And this is actually studying these galaxies as kind of the main brunt of most of my research. But today, instead of talking about what we'd call late-universe cosmology, all these galaxies, I'm going to take you back to before the Big Bang, so the earliest that we talked about when we talked about cosmology. And so, we know, it's a little faint on the screen, but we know that the early universe was filled with this big, hot plasma. We call it the primordial plasma. The universe was super dense, super hot. None of the galaxies, planets, anything you know today exists. Everything is just a big super particle's interacting. And we know this is the case because we've seen it. We've actually taken a picture of the Big Bang, and that's what we call the CMB, the Cosmic Microwave Background. There's answer number one for you. And this is the beautiful picture taken by the WMAP probe, a satellite that took an image of the Big Bang for us. And what you see here is the whole night sky. It's just laid out flat on the screen. And we see the colors on this map are showing you the temperature of this primordial plasma, that hot fireball that started the universe, how hot it was from position to position. You can see some spots are hotter than others, some parts are cooler than others. And this gives us a lot of information about the early universe, and the observation of this was kind of the thing that solidified the Big Bang is like real verified science. And so, you might wonder, you know, what does it even mean to take a picture of the Big Bang? Did the Big Bang happen 14 billion years ago? How do you have a picture of it? And so, what's important to understand is that when you take pictures of things far away in the universe, because light travels at a finite speed, it takes that finite time to get here. And so, the further away you look in the universe, the further back in time you're looking. And so, the nearest star to us is about 4.2 light-years away. So, when you look at this star, you're seeing what that star looked like four years ago, because it took that light four years to travel from that star to Earth. And you see that's about 2.5 million light-years away. So, when you look at Andromeda, you see what it looked like 2.5 million years ago. And if you look far enough away, if you look much further than 14 billion light-years away, you'll see light that took 14 billion years to reach us. And that light is the Big Bang, and we see it coming from every direction. And this is the furthest thing you can see in the universe because there's nothing to see beyond that. That's the light emitted from the Big Bang. And so, seeing this is what kind of confirms the understanding of what the Big Bang was, what it looked like. And so, there's this wonderful multi-decade campaign to measure precise details of exactly what this looked like. So, Kobe, back in 1992, measured what this looks like on the left here. I've kind of just spliced it so you can see the three different satellites. Kobe won the Nobel Prize for this defection. And then WMAP in 2003 and Planck in 2013 added more and more detail. And what's exciting about this is all of those little fluctuations that you see in this map were small density fluctuations in the early universe that then, once you evolve after the Big Bang, you let gravity take over, all of those little perturbations collapse under gravity to form the structures we see today. So, on the right here, you can see simulations that are showing, if we wait till the beginning here, it's kind of smoothed out and over time everything collapses onto the denser stuff. So, the denser stuff gets denser and denser and that's how you form stars and galaxies and everything you see around you today. And so, this stuff forms, yeah, planet Earth and us and everything. So, by measuring the Big Bang, by measuring the CMB, we can kind of get an understanding of how the universe started and how it evolves into everything we can see today, which is super cool. And it's kind of insane how much information is contained in the Big Bang. Every cosmologist gets up in the morning and bows down to the CMB because it tells us, almost everything that's predicted by our cosmological model, you can test against the CMB and the measurements of the CMB are so incredible that when they show you plots in the CMB, the error bars are smaller than the lines that they plot in. It's incredible how well they've measured this. And so, this is really exciting cosmology. However, it doesn't tell you everything, right? So, the Big Bang, the CMB tells us that we have, most of the universe is dark energy and dark matter, which I'm not going to get into details up today, but to summarize, it's a big WTF. We have no idea what the hell this is. We know how these things behave on a cosmological scale, how it impacts, for example, the expansion of the universe and formation of galaxies, but we have no good physical theory for what this stuff actually is. There's lots of ideas. We're working on it. There's also fundamental questions about our picture in the CMB itself. And in fact, this picture that I show you here is a little bit of a lie. This is not exactly what it looks like when you take an image of it. When we image it, it looks like this. It looks the exact same everywhere. Every direction you look is identical. And what I mean by this, right, is imagine we have this plot here where on the x-axis is position and on the y-axis is the temperature. That's really what you're looking at when you look at those fluctuations, those temperature fluctuations. What we see is the exact same temperature everywhere, which is pretty remarkable, but if you zoom in by a factor of 100,000, so really if you bump the contrast up by 100,000, you see tiny, tiny, tiny wiggles, and that's what that picture is going to show you. You subtract out the mean that's the same everywhere, right? And what you see are these tiny residual fluctuations. But we're still left this idea that the temperature of the universe of the CMB is everywhere you look. And what that means is that during the Big Bang, every single point in the entire universe had the exact same temperature. Sorry, I got a point in the right direction. So the CMB says that at the end of the Big Bang, the entire universe is basically the exact same temperature. And that might not be weird, right? Because we know that if we let things interact, you know, if you've let this glass of water interact with the room around it, that eventually they're going to come to the same temperature, right? They interact, they exchange energy to reach thermal equilibrium. But what's weird is that we know in the standard picture of cosmology that the Big Bang does not last long enough for the universe to kind of sit around, exchange energy, and for all to come to the same temperature. So we don't know why the whole universe should be the exact same temperature. And to give you kind of an idea of why this might be, right? If you remember, you know, we're here on Earth. We're imaging with this light that took 14 billion years to come from where the CMB is all later at the right. Well, it would take at least another 14 billion years for that same photon to pass by the Earth and hit the part of the CMB over here, right? So these two parts of the CMB are completely out of causal contact. They have never exchanged photons. They've not talked to each other. They haven't exchanged energy because they're at least 28 billion light years away from each other and the universe is only 14 billion light years old. 14 billion years old. So we have no reason to expect that this part of the CMB on one side of the sky should be the exact same temperature as the part of the CMB and the other part of the sky. Because those two regions of the universe have never been in contact with each other before in the history of the universe. And in fact, it's even worse than that because not only have two parts and opposite part of the sky never been in contact, but when you look at the distance away of the CMB, no two points that are a degree apart from the sky have ever been in contact. And so if you're looking at a picture of the CMB and you hold your pinky up at arm's length, that's one degree. Any two points beyond that, you should expect to have different temperatures. And so it's weird they all have the exact same temperature. And if you have any idea of how weird this is, it'd be like if you and two of your friends drove here tonight for a restaurant tap and you each made a cup of coffee at home before you arrived. When you get here, you know, as normal people do, you measure the temperatures of your coffee and you compare them. And you say, whoa, all of our coffees are exactly 173 degrees Fahrenheit. That's such a weird coincidence, right? Well, because of the precision at which we measure the CMB, it'd be like if you said, wait, all four of our coffees are exactly 173.2248 degrees Fahrenheit. That's gonna get kind of weird, right? It's like there's some conspiracy, right? But because of this one degree thing, the CMB is not this situation. The CMB is all 40,000 of us have coffees that are exactly 173.2248 degrees Fahrenheit. Like at this point, you're like, this is not a coincidence. There's some like grand conspiracy. Something has planned us out, right? This doesn't make any sense. And so we're left with this big question. The CMB is way too uniform. It has the exact same temperature everywhere and it shouldn't, we don't know why it should. And we call this problem the horizon problem. And so it's kind of this big open question left by the standard model of cosmology. Cosmology works as long as you assume that the start of the universe has these really weird conditions that we don't expect to be true. And so that's gonna lead us to this idea of what happened before the Big Bang. How can we explain this horizon problem, this really weird condition where every point of the universe has the exact same temperature? So here's a possible solution, right? Maybe there is some conspiracy. Maybe all three of you, I'm the fourth person, like why is our coffee always in temperature? Maybe it's because all three of you started at the exact same spot. You were a lot closer together in the past than I thought you were. You didn't come from your houses. You came from some secret location on the other side of Green Lake. You all poured your coffees from the exact same coffee pot. And then timed it out and made sure you got here right at the same time. And you're like, oh wow, our coffee. Isn't that weird John Franklin? And inflation is what we think happened prior to the Big Bang. And it's the analog of this for the CMB, for the universe. So this standard model here on the x-axis is time. On the y-axis is a measure of the size of the universe. Here it says radius of the universe. And this line here is kind of that original cosmology model. The model where I thought you all came from your own houses, right? If you extrapolate the size of the universe back to early times where it hits the y-axis tells me you guys were not close enough to each other to possibly have the same coffee, right? Doesn't make any sense. For some reason there's some weird coincidence why our coffees are the exact same temperature. Instead we postulate maybe there's this period of inflation before the Big Bang where the universe goes through this super-exponential phase of expansion. It expands super, super, super fast. Insanely fast. So that you weren't this close apart in the past. It actually turns out in the past you were a lot closer together. And so this allows every point in the universe to have the same temperature because now they're not widely separated and didn't have time to communicate. Now they're actually super, super, super close together and have plenty of time to communicate. And so this allows everything we see today back here when they're super close to reach the same temperature. I think they go through this huge, like, huge expansion. The normal expansion follows that to expand to the universe we see today. And so we think that maybe everything is the same temperature because they were together really, really young. And so we realize that origin. And so to give you an idea of, you know, kind of how explosive the expansion of inflation is, I'll give you two examples. So here in a billionth of a trillionth of a trillionth of a second that's kind of the shortest we think inflation could have lasted. Oh, that's so funny. We think a hydrogen atom blew up to the size of, of what, anybody have a guess? That'd be pretty modest. No, we think in a billionth of a trillionth of a trillionth of a second, if anybody can hear, he guessed a helium atom, which is barely bigger. In a billionth of a trillionth of a trillionth of a second, we think a hydrogen atom blew up to larger than the size of the solar system. And that same time span, we think a human, so any one of you, any one of you lucky participants, could become larger than the size of the entire visible universe. So this is, like, insane expansion and just, like, such a short amount of time that you can't even comprehend it. Like, what does that number even mean? But, we think this happened because it solves the horizon problem, right? It allows all the points in the universe that we see today to get together at the beginning of the universe and conspire to all be the exact same temperature. So that when we see this EMB we see today that looks super smooth, same temperature everywhere, it all makes sense. So now we should talk a little bit about why inflation happens. And we're going to talk about this because this allows us to set to the weird stuff like the multiverse, so get ready. So we think that there's this extra field in the universe. It's a scalar field. So kind of like, if you think of, like, temperature or pressure, that's, like, a value that's associated with every point in space, right? There's a temperature right here, the temperature right here, the temperature right there. There's an extra value that we hypothesize called the inflaton. And this is no different than, like, for example, electromagnetic fields, except rather than having no direction, like an electric field has, it's just a value in a single point. And so every point in space has this inflaton field that has some value associated, right? There's also a potential energy associated with that field. You can think of this as being kind of like, you know, a soccer ball sitting on a hill, for example. When it's up on the hill, it has a lot of gravitational energy, right? And if you kick it down the hill, that gravitational energy converts to kinetic energy. It rolls faster. You know, kind of normal physics you might have learned in high school or college if you took some physics. But what's important is that we think in the early universe, this value of the inflaton, here the ball represents the value of the inflaton at every point in space. It wasn't at the bottom of the hill where we expect it to be. Somehow it got stuck up on top of that hill. And being up on top of that hill means the inflaton now carries a lot of energy. It's kind of the, you know, the analog of gravitational energy, except this is not gravitational energy, this is just, you know, quantum mechanical, inflaton energy. I'm sure you all get it. But the point is, is that the expansion rate of the universe is controlled by the energy density of the universe. More energy, more expansion. And so this means that you get a whole bunch of extra energy that shouldn't be there. It's like trapped up in this field and that causes the universe to expand exponentially. And so this field, it starts to roll back down to the bottom of its potential. But while it's stuck up on this plateau, you get that exponential expansion. As it rolls down, it's slowly moving. You know, the universe is expanding. You know, you've become large in the universe. You're going crazy. At some point, it rolls off that plateau and back down into this valley and inflation stops. And that's what we think is kind of the start of our regular big bang. And it kind of oscillates back and forth around this minimum, kind of like a ball would in like little divot until it comes to a rest. And that shaking back and forth is what creates all the energy that creates that primordial plasma. It converts all of this energy into the energy of protons and electrons and neutrinos and everything that makes up everything around you today. But what's really cool is while this expansion is happening, you also have quantum fluctuations. And so quantum mechanics tells us that things don't like to sit still in the universe. At every point in the vacuum, you know, if you imagine an empty space, you might think it's totally empty, but there's all these different quantum mechanical fields that are fluctuating up and down. So for example, there's a field associated with the electron. The electron field is popping up and down. You can think of that as like an electron and a positron. So matter antimatter pairs popping in and out of existence. And this is happening for all the different particles you know. Photons, electrons, protons, et cetera. They're all popping up out of existence because quantum mechanics tells us that the universe fluctuates at this really tiny level. What's really cool is this exponential expansion from inflation. It takes those tiny quantum fluctuations and blows them up to mass presopic scales, right? So in that, you know, billionth of a trillionth of a trillionth of a second, this tiny quantum fluctuation that's like invisible in normal circumstances might get blown up to the size of a planet or a solar system or a galaxy. And what happens is all of those tiny fluctuations that we saw in the C and B are actually those tiny quantum fluctuations blown up by inflation. And if you remember, those fluctuations in the C and B are the density fluctuations that collapse into galaxies and solar systems and planets and form people and plants and everything around us, right? So you might be familiar with the famous quote from Carl Sagan where he says we're all stardust, right? Because the elements that are in our body were forged in the fusion of these giant stars. You could say the same thing, that we are all quantum fluctuations, that we think due to inflation that everything around us today, everything that exists, was born from these tiny, tiny quantum fluctuations that were the big thing. And that's what's really cool about inflation is it connects the quantum to the cosmic, the tiniest scales that we know about to the largest scales we know possible. So we introduce inflation to solve the horizon problem, to explain why the universe is the same temperature everywhere you look. And what's cool is it pops out, it was not invented for this reason, this is realized afterwards, that inflation plus quantum mechanics means you get all these density perturbations that collapse the form galaxies in us. It does even weirder stuff, and this is where the multiverse comes in. So, if you remember, every point in the universe has a value of this field that's slowly rolling down this hill, and when it rolls down to the bottom inflation ends, right? But because of these quantum fluctuations, every point, you know, that ball doesn't smoothly roll down the hill like a soccer ball would, right? As it rolls down, it's kind of jiggling back and forth in random ways. And what that means is that because of these random fluctuations, when it rolls down the hill, you have an infant on here that's rolling down the hill, because of these fluctuations, they won't reach the bottom at the same time. So over here, inflation can't end at the exact same time it ends over here. So you have different patches of the universe that are going to end inflation and kind of start the regular Big Bang at different points in time. So let's talk about what this means. I don't know if you can see that in this daylight. There's a red dot there, it says inflating, right? So this is our tiny inflating universe, and if you go one step later in time, let's assume that almost all of the universe has now stopped inflating. It's normal Big Bang, it's going to go on and create people and everything we know. But there's this tiny patch that because of these quant fluctuations isn't quite done inflating. It's going to keep going for just a little bit longer. Well, it's crazy because this thing is inflating exponentially. If you go one step later, it now doors everything that's stopped inflating. And you can repeat this, right? You can say, okay now assume 99% of this stops inflating. That 1% that's still inflating is going to go on to dominate everything else. And so what this is telling you is that you can't stop inflation once it starts going. It just keeps running and running. And you end up in this situation where you have these little pockets, these little bubble universes that are post-inflation. They used to be inflating, they stop inflating. Now they're forming normal universes, as you and I know and love. But they're separated by this red region. This kind of exponentially expanding space that's expanding forever at insane rates and forever pushing them farther and farther apart in this kind of larger meta-universe, right? And so here's an artist's conception of it, much prettier than what I drew in PowerPoint. So here we have these little different bubble universes. And what's really crazy about this is we don't think anything exists in that expansionally expanding space between these little bubble universes. But using the laws of physics, you can kind of imagine what an observer that was kind of floating out in the existential space looking in at these bubble universes would see, right? And what you find is really weird. From the outside looking in, if you're in that inflating space looking in at this bubble that stopped inflating, you would see a finite universe. You'd say, okay, this patch has stopped inflating. Here are its boundaries. But someone inside that universe looking outwards would see no boundary. They would think they live inside an infinite universe. And this is just one of the weird things that happens in general relativity. You might have heard similar things about like black holes. Like if you're watching someone fall into a black hole, it looks like they never actually enter the black hole. But the person who is falling in would enter the black hole and would experience that. So these weird things in general relativity can observe totally different things. And so this is a case where someone looking inside says this is just a tiny bubble and someone inside says I live inside an infinite universe. And so this is the inflationary multiverse. And each one of these is called the universe for a good reason, right? Because people living inside them think they live inside an infinite universe. Even though it's just a bubble embedded inside a larger thing. And so it's kind of like, you know, a Mary Poppins purse kind of thing where on the outside looking and it looks by night inside, it's a lot bigger than you would have expected. What's even weirder is if string theory is true, which is a big F, very controversial. If string theory is true, there's reason to think that each one of these bubbles might have a different set of laws of physics. And so it's happening inside each one of these bubbles can be totally different. And in that case, it truly is like a sci-fi multiverse that's just like insane to think about. Most of them would probably be empty with no life. This might push you down towards if you've ever heard of anthropic reasoning, like trying to reason like, oh, well maybe we live in the only universe that suits us. Like that kind of thing. This is a very viable loop for that. So we invented inflation to solve the horizon problem to explain why everywhere in the universe has the exact same temperature. Out pops these quantum fluctuations that create, you know, everything we see around us today. But oh, it also creates an infinite number of other universes. It's kind of crazy. But we have very good reason to think that inflation is true because this prediction it made was super non-trivial. There's like six or seven very specific things it predicts that we've gone and checked and they all passed with flying colors. And so a lot of people are kind of uncomfortable with this fact that it also produces a multiverse. And, you know, depending on your philosophical explanations, you might say like, oh, well, that's not what we wanted, but the theory does correct everything else, right? So maybe this is the natural implication. Some people say, you know, this is too much, right? You wanted to solve a simple problem and now you've created a whole multiverse, like what the hell are you doing? Most cosmologists think inflation is true. They have very good evidence for it. But there are still a few people that are working on the fringes trying to see if there are other ways that you can solve these problems and not introduce this whole multiverse. A popular alternative is what's called a bouncing cosmology or a bouncing universe. We have a universe that's contracting and goes really dense and then expands and that looks like the Big Bang. It expands a long time like ours does, but slowly slows down at some point, turns back around and collapses and the process repeats itself. They're working very hard on this. They're not doing very well so far. Bouncing cosmologies have a lot of issues. I mean, for one, it's hard to make them bounce. We don't really know how you can get it around when it's going in and how to make it go back out. It doesn't predict all the perturbations we see, like inflation does. You're going to have to put those in. You have to engineer those in yourself. It kind of opens up a whole Pandora's box of other problems that most people agree are a whole lot worse than the problem you're trying to solve. It's an important way of people thinking about this to try to understand if there aren't any viable alternatives to inflation, but so far none are profitable. But what's exciting, inflation has made it confirmed, but it also makes a whole other list of predictions that haven't yet been confirmed. For example, one is that inflation should also create gravitational waves. There are lots of telescopes looking for the gravitational waves from inflation. This one is the Bicep Telescope in the south pole. There's also information we can learn about inflation by looking at very specific details of galaxies in the late universe and look at how far they are separated from each other. If you look at correlations of where all the galaxies are located and you do that really precisely, you can extract some information about those earliest moments of the universe's creation. This is all a very, very active research field right now. Hopefully in the next 10, 20 years we'll have a better idea of if inflation happened and exactly what form it took. And that's the end. Second? Yeah, so the question was is there only one level of multiverse? And is our multiverse maybe one multiverse inside of a larger thing that has lots of multiverses? There's no reason for us to think that. So you can speculate about it, but there's nothing that drives us to that conclusion. And physicists don't like the multiverse, so you kind of have to be dragged into it kicking and screaming to believe it. If you believe the mini-world interpretation of quantum mechanics, that's kind of a different variety of multiverses which also might be true. But it's a little bit different than inflation. Yeah, so he asked, is JWST adding any new information that can help us constrain inflation? And I don't think so. JWST kind of observes this kind of late stage of all the galaxies exist. And if you want to use galaxy information to constrain inflation, you have to use large surveys of galaxies to do these huge correlation functions. And JWST is kind of more of a focus on something really fine and take really precise information rather than gather tons of information across the whole sky. Rachel, how do we know how accurate the measurements in C and D are? So I don't work on those telescopes. I don't know how they take it. They have very precise quantum technology that has to do with semiconductors. They use to measure these temperatures. And there's decades of work going in to make sure that the readings are precise. And they probably calibrated against some source in the sky. But that area of astronomy is so different from optical astronomy, which is what I work on, that it's basically like they're speaking French. It's a different language. Yeah? So the question was, if only 5% of all the stuff is normal matter, where is that other 95%? Does inflation tell us where that stuff is? And inflation doesn't tell us where the dark energy is. It tells us where the dark matter is. And it says that it should be in the same location as the normal matter is. And that's carried out, that's corroborated by all the normal evidence we have from like galaxies. So for example, every galaxy we know of, lives inside a giant cloud of dark matter. So we kind of know where all the dark matter is. Dark energy looks like it's totally uniform, equally spread out everywhere. And so we have good evidence for that as well from supernova information. And whether or not it localizes anywhere, or whether it says perfectly spread out is a current hot field of research as well. So yes, so there are laser interferometers that are used to detect gravitational waves. And they are hoping to build experiments that can detect, can directly detect kind of the spectrum of gravitational waves from inflation using these large space-facing interferometers. I think the proposed versions of the experiments are supposed to launch in like the 2040s at the earliest. So it's not imminent, but... Could they show us anything that... So you can't observe inflation with... Well, you can't observe the times of inflation directly with like normal electromagnetic telescopes because the C and B kind of acts as like a wall that you can't see beyond that sense. Yeah, so the question was, how quickly do our ideas about inflation change? So the earliest forms of inflation were proposed in like the 70s and 80s. And they had some clear deficiencies that didn't work. So rather quickly, people worked very hard and kind of patched those holes and invented inflation as we know today. And the inflationary period is basically in place since like the 80s with the observational evidence getting better and better and better. There are kind of theoretical developments that are going on the side that are kind of nearing our view of what inflation can be. So one of the quote-unquote problems with inflation is that... I mean, this is actually a good thing about inflation. The good thing about inflation is it's not fine-tuned in the sense that you don't have to come up with some super contrived theory of inflation to make it all work. It kind of works so easily that the details don't matter. Now, that's a problem if you want to figure out exactly what inflation is like on the particle physics level because the data we have kind of agrees with most models of inflation, right? And so there's a lot of data collection and a lot of theoretical thinking going on that's working very hard to kind of weed out the different possibilities of what inflation can be. And so that's kind of particle physics detail that I didn't get into here. But the kind of stuff that I covered here has been in place since like the 80s and hasn't really changed, and we don't really expect to change. If it did change, you know, it's going to be... it will be one of those scientific discoveries that would be on the New York class. It would be big news. So thank you very much. Feel free to come find me in Ask Questions if you want to ask questions outside of class. All right. Let's paint J.F. one more time because that was fantastic. J.F., can I have the clicker, please? The clicker, the one that advances the slides, thank you. So now I'm going to announce the trivia answers and the winners. And then we'll take an intermission and finish off with our last talk. Okay, so let's do answers before winners. First question. Wait, is this for the answers? Oh, I see. I'm pressing the wrong button. Okay. What is the cosmic microwave background radiation? It is all of the above, which hopefully you know by now. The Holmedel Hornetana was the first telescope to measure cosmic microwave background radiation. And it was by accident, actually. Come ask J.F. about that if you want. The Lambda CDM model is the model considered to be the standard for dark matter in the model of the universe. Okay. Three degrees Kelvin is the average temperature of the universe, and actually it's not a degree. Is Kelvin a degree? It's just Kelvin. Three Kelvin. I should know this. The universe is not a giant soap bubble, but I think more correctly, we don't know what it is. Right? So the first asteroid discovered was named Ceres. Asteroids can, in fact, have moons and rings just like planets. 1898 was when the first near-Earth asteroid was discovered. The Earth Protection Protocol is not an astronomical program dedicated to the discovery of near-Earth asteroids. Fun fact, we had a different one originally as the false answer for this, and then came to find out that it was actually a real program. Okay. 35 miles away was how far the 1972 Great Daylight Fireball Meteorite was. Meteor was. So, we have a first-way tie for first, a two-way tie for first place with nine answers correct, and we have a two-way tie for second place with eight answers correct. Crazy. I know. So if you win trivia, fourth or second place prize, first or second place prize, wait until the end of the second talk to come get your prize. Our second place winners first, and all the prizes are the same, but you get bragged, right? First second place winner is Star Geysers. Yeah! Nice! And our other second place winner is O'Ryan. Nice. Well done. Okay. Our first first place winner is Singularity of Evil. Nice. Well done. And our other first place winner is Plucky Planks. Okay. So at this point, we're going to take a five to ten minute, probably closer to ten minute intermission so you guys can get another drink or a hot dog if you'd like, and then we will come back with our second talk of the evening. Thank you. Thank you. For months of alcohol, except for Tom, to get started now. It's a pleasure to introduce our second speaker of the evening, University of Washington. He is also my office mate at the University of Washington, and when Tom was a teenager, he discovered a plan. By saying, if you think I sound strange and you're American, it's because I have English. And if you are English, if you think I sound strange, it's because I've lived here for like six years now and it's kind of sinking in. So yeah, I'm going to talk about the opposite end of the scale. So instead of the biggest astronomy, we've now got the smallest astronomy. We're bringing it back down to Earth. And we're going to be talking about near-Earth objects. There's some recent research that will hopefully be submitting on paper next week. So we should see. So, what is all this fuss about the sky falling and why should you be working? So currently, you get about 10 to 30 potential near-Earth objects being followed up every single night. At about 25% of those end up being actually near-Earth objects. The things we're actually looking for. That's very manageable. So the problem is, we're about to have this new survey, new telescope come in line. And what we're going to see is those numbers are going to change quite drastically so that we're going to be seeing 1,000 to 20,000 of these things every single night. And only about 3% of those are going to be the things you're looking for. And so this means we might end up missing near-Earth objects. And you can imagine if an object is near Earth and we know about dinosaurs, we should like to know where all of those are. And so essentially, if we look at the near-Earth object follow-up system as it currently is, it's very organized, everyone's ready. But once LSST comes online, and I'll tell you what that is soon, it's going to be absolute chaos if we don't do something to prepare. So I'm going to tell you about how we should be preparing for this. So basically what's going to happen is we're going to talk a bit of background. We're going to say, what are near-Earth objects? Why should you care about them? Why are they important? And what's this LSST thing that I keep talking about? What is the impact of LSST? What is that going to be on the near-Earth object follow-up? And it's going to be bad, hence I'm giving this talk. And then how are we going to mitigate that impact? What can we do to prevent overwhelming it? And what are the implications of this? How do we need to prepare in the next year and a half or so before things start coming online to stop things from burning down? So let's talk background first of all. So near-Earth objects, sort of in the name, is an object that is near-Earth. They tend to be mostly asteroids, some comets, and the fancy way of saying it is it has a perihelium distance less than 1.3 AU. So its closest approach to the Sun is about 1.3 times the distance from the Earth to the Sun. So things that are nearby. And you're all looking a bit relaxed, so let's stress you out a bit more and say that about a fifth of these near-Earth objects could intersect with Earth's orbit with any sort of small perturbation. Say another asteroid hits them and they end up coming in, you're going to be in trouble. And to stress you out even more, only about a third of potentially hazardous objects is the ones that are going to cause continent-wide devastation are currently known. We estimate there's two-thirds of them, they're just out there and we're not keeping an eye on them. So I hope you sleep well tonight. So why do they matter? Well, you know, first the obvious one, planetary defence. NEOs pose a huge threat to human civilization. We need to be watching out for these potential extinction level events. We need to monitor all of those potentially hazardous objects. You know, that's kind of the obvious one, but there's also some other interesting things where you can think about resources. So after space, you can find a bunch of materials that are rare on Earth just like hanging around in asteroids. And so instead of going out far into space and looking for these things, you just wait for them to come to you. Wait for your nearest object to come along, grab all the stuff, mine it, sell it, I guess. But that's, you know, that's a bit commercial, but you could think about astronauts and how it's kind of a hassle to get things out of the gravitational potential of Earth, like you having to fly up a bunch of like water, for instance. That takes a lot of fuel and then that fuel is heavy, so you need more fuel to get that fuel out and then it all gets chaotic. And so instead you could just go to an asteroid nearby, got some water on it, take that, you're asked, you know what's that water? Great. And then the other thing is looking at the formation of the solar system or planetary formation in general. These asteroids are essentially untouched. They are pristine from the very start of the solar system. They haven't had all of these geological activities and things that have changed the kind of composition of things that are on Earth. The asteroids are exactly like they were right at the start. And so this can be a perfect way to study those early solar system conditions to work out how formation happened, things like that. So those are nearer objects. I do want to also briefly mention the main belt of asteroids. So this one you've probably heard of, this is the one hanging around between Mars and Jupiter. And this is like a large population, like easily like 10 to 100 more than you're going to see of the nearer objects. And that's going to be important because it's difficult to distinguish between the two. We're going to be fighting between main belt asteroids, that's MBAs, and nearer objects a lot. So keep that in mind. So how do you take a nearer object or take an observation of an asteroid and how can you tell what it is? What you need to do is first form a traffic. So you can imagine you take a picture of the sky, like you take one picture and you see that an asteroid is hanging out about there. And then you wait, I don't know, half an hour, you come back, you take another picture and it's moved. Now it's there. You wait, you come back, it's moved, it's there. And so what you can do is string these together into something called a tracklet and that gives you its rough trajectory on the sky. And then you do that one night and then you come back and you do it again and you go, one tracklet, you've got another tracklet and then you can draw an orbit along. And basically, based on that orbit, you can work out is it something that's going to come close to the Earth? Is it something that's just hanging out, you know, between Mars and Jupiter? And based on that, you can then say, is it a nearer object? So to do this, we use a code called digest2, which I'm saying here because it still amuses me that no one knows why it is called digest2. There isn't a digest1. I don't know what it's digesting. But that's going to give you a score from 0 to 100. 100 is like, that's an NEO. And 0 is like, that's not an NEO. And it doesn't actually work that well, so I will show you. So lastly, let's talk about the legacy survey of space and time. This is the LST that you'll see. You can see this is now quite beautiful down in Chile. You've got this huge 10-year optical survey that's going to go on from the Vera Rubin Observatory. And this is going to be doing a bunch of things. So there's like four main science goals that they like how could you blame dark matter, dark energy, solar system, which you know, clearly most important of these. And then also, you've got optical transits. And maybe mapping the Milky Way. But we're not going to worry about those. We're focusing on the solar system. And specifically, this thing is important because from day one, it is going to rapidly change the way that we are discovering near-earth objects. We are going to see over the course of those 10 years that of all of the like sizable near-earth objects, we're going to find about three-quarters of them, like in the entire solar system through one cell. So this thing's going to have a big impact. So hopefully now, you've got a bit of an idea about what a near-earth object is, why you should care about them, and what this LSST thing is too. And now let's talk about the part where the sky is falling and why we should all be panicking. So what we want to do, what we've done in this research is try and make predictions. So what you need to do is first create a whole catalogue of fake objects. What do we think is out there in the solar system based on models of what we've got? Then we need to do kind of simulated observations. So we don't have the actual observations yet. The survey isn't going yet. So we're going to do some mock observations. And then we need to classify those observations. Are these things near-earth objects that we're seeing or not? Are we getting infused? Things like that. So first step, you'd think it was quite easy because there's a bunch of existing catalogs out there. This one is called the S3M. But it's not quite that easy because the problem is they don't account for prior detections. They just give you everything in the solar system. But we have found things in the solar system. We know there are planets. We know there are certain named asteroids that you saw in trivia. And so you can end up with a situation like this where you've got your plan and you're like, here's what I'm going to do. I'm going to take a fully synthetic solar system catalogue. I'm going to perform my mock LST observations and then I will predict the rediscovery series. But we already have series. So that's kind of not very useful. So this is problematic. So instead of doing that, what we're going to instead do is create a hybrid catalogue. So this one is combining both real and simulated data. I'm going to skip over like how we do this. But essentially, it goes in and injects real data into the simulated catalogs in a consistent way so that you can tell which things you've already found so you don't predict things you've already found. So we don't have to worry about that. That's good. And then for the simulating and classification of the observations, we know that the survey is going to follow this particular strategy. It's just going to kind of sweep across the sky. It's going to kind of patch it all together in a particular way. And so we have this scheduler code that can tell us where it's going to look. The camera is going to look like this. You can see like the moon is fitting in here. But I think this is kind of cool. I don't know how well you can see this. You can see how much space there is there and like clouds and stuff. But you can resolve a gulf ball because the camera is that precise. It has that high resolution. So that's cool. And when we're doing this we account for things like the code accounts like is there downtime? Is there bad weather? So it's like a realistic prediction. And then finally the classification. We use that digest2 code where we have no idea why it's called that and that gives us the score tells us where we got nearer objects. So we've done all our things. Let's see what's happened. So I'm going to show you a plot which everyone loves looking at plots. Like plot to plot with something, right? So the top panel that's going to show you the number of objects. This is the traffic. So this is like how many things we're going to see every single night. The bottom panel that one is going to show you the fraction of those objects that are actually nearer objects. Then xx is here we've got the night nearer observations going from like March till, you know, March. That's how years work. Just joking. We've also, these are log scales with the highlights. So these are like factors of 10. So they're like 100, 1,000, 10,000. So it's a big range. So now for the chaotic plot it looks something like this. So I encourage you to just focus on the dark line. Ignore the more colorful ones. I'm not going to, you can ask me if you want to know what they are but the point is what you can see is that you're going from like tens of thousands to like maybe just thousands. It's a lot of things every single night and your purity is never going above 0.1. It's going down below a percentage here. It's very, very bad. Also just briefly the kind of what's the word? Trends that you're seeing here. You can see there's a peak in like the summer and then it kind of flattens out towards the winter. There's a little variation where the ecliptic plane like the plane of the solar system is going up and down and you'll find more or fewer main ball asteroids. And now, see if you can work out what this one is. You see how there's like a dip there and then there and then another one there and then there. It's happening about every 30 days slightly fewer than 30 days. What's in the night sky that you think might be causing this issue? The moon. Every single dip you see there is a full moon because it affects where you point the telescope and what filters you're using. So it basically messes things up. So you see these like dips which I at first didn't know what that was and then I looked up the date of the first one and I said it was a full moon and I was like wait a second. So summary your traffic is going up by like 100 to 1,000 times. Your purity is going up down by a factor of 10. Everything is awesome. LSD is going to overwhelm near-object communities and so everyone in the follow-up community is currently terrified and worried and we need to do something about this. So what do we do? Well LSD is sending a lot of these extra things to the community but it could also do a lot of the work itself. A lot of the time it's going to re-observe these things by itself. It doesn't need help. The problem is you don't know that straight away. You need three nights of observations in your window to get a discovery. So you can have night one and you get a tracklet and then you get another tracklet at night three and another tracklet at night four and then you get your discovery but you need to know a night one and so the problem is we don't know in advance which one of these objects is going to get observed again. We don't know which ones to submit so we need to make a decision on the spot rather than just submitting everything. So night one is this thing going to be good or not? Well in that case if we shimmer into a magical world the spot looks so much nicer. Like look we're seeing like one to maybe a hundred things every night. That's chill. The things are like 25% purity. Great. Excellent. So now all we need to do is predict the future and that brings into section three and you know it's not as hard as you think. So let's say okay we've got one tracker we see an observation we see the thing move so we can tell roughly where it's going. You know there's a bit of errors on that so you can't tell exactly where it's going to be. You've got some idea of where it's going to be you also know some idea roughly of where the telescope's going to point maybe you can make a prediction. So you've got your initial two observations but we could fit an orbit that goes through and then on that next night it lands in the camera. Great. We see it. So we don't have to worry about this one. But we could also have an orbit that goes through and fits just as well and misses. Or we could even have an orbit that goes through lands in the camera but then it's too far away and it's too faint and you wouldn't see it anyway. So you have to account for all these things and all these different orbits fit. So basically what we need to do is find a bunch and not only move their position but also how bright they are and then predict where the telescope's going to look. And so basically the first part for the orbits you can imagine you've got your track there and you're looking at it down from Earth. The problem is you can tell where it is on the sky and where it's moving but you don't know how far away it is or whether it's moving towards you or away from you. Like imagine you could have that track and you could see something that's fairly close and moving and you could equally have something that's further away and moving faster and you'd end up with exactly the same track on the sky and so it's very difficult to tell the difference between two. So basically what you have to do is make a whole grid of distances and radial velocities and you get like a big sample of orbits that might fit and it looks something like this. So the stars in the background right away are completely fake I just added them for fun but you've got something interesting and all of those different purple orbits all fit the observation so you can see you can have a very different trajectory just based on that one observation so it's kind of uncertain but we can test all of those orbits and check which ones of them we're going to see which ones of them are near with objects and that can help us. So we do that we put them all together and so I basically I'm skipping some details here but wrote up an algorithm that doesn't and so it then basically just says end up being a discovery which ones don't that gives you a fraction you've got a probability and based on that probability you can choose whether to submit it for external follow up great. It works pretty well we can predict the future about three quarters of the time just over three quarters of the time and this makes life much better so now instead of having you know a thousand to twenty thousand things every night you only get like two hundred like that's manual we can do that bad news is purity is still pretty low we're only getting about five percent of those things being nearer of objects and this is because we've got so many main ball asteroids that are just messing things up so what do we need to do to repair we've kind of got that traffic now we can put my algorithm into the minor planet center and that will help but it's not going to completely fix this so we basically got two kind of directions we can take this with the problem is we've got so many main ball asteroids that we haven't seen before so either we can improve this digest two code and try and find a better way to distinguish between these two different populations or we can just wait we can just wait until we find all the main ball asteroids and then just focus on the nearer of objects after that so first off just improving the code there's a bunch of things we can do so like currently we don't think about eclipsic last which is a fancy way of saying how far is it off the plane it's not going to be in the plane in the main belt so that could be a nearer of object so that's something to think about we can think about how bright it is nearer of objects tends to be fainter we can think about the direction of motion so if you're in the main belt you can imagine you're probably not going to be moving straight out of the main belt or else you wouldn't still be there so you tend to be along the plane whereas if you're a nearer of object you could be going any direction so we could use that and basically that rapid rotation is going to change how bright it is because different sides maybe have different like reflectances or just a slightly different shapes or different sizes and so you get this like variation in the light so that's another thing we could look at so I'm going to get other people to do that rather than me though and then the other thing is like okay what if we just wait it like instead of trying to now go through all the hassle of improve this goal what if we just wait but over time this is over the 10 years of LSST we find the main belt asteroids much quicker like the purple line you can see decreases rapidly and then meets the orange line which is the nearer of objects so by the time you get to like year four or five you're getting about the same amount of them every single night and you can distinguish them pretty well when they're in similar numbers so that would be easy so even by like year two we can get to the point where nearer of objects follow up would be pretty easy so we just have to delay the problem is the nearer of objects follow up can you see it's then going to be kind of bored for two years because like what do you do if you've got nothing to look at but that's okay so in that case you just focus on the things that are really far away from the plane there's enough observations that's still a fairly sizeable sample so people can do that and that's pretty much it so just recapping what we've gone through LSST is completely overwhelming if we just do things as we are currently doing them without making any operations things are going to be bad we might miss a nearer of object we'll blow up we can make predictions for whether LSST is going to follow things up all by itself and this works for reducing the traffic back to normal but the purity stays pretty low because of these main ball asteroids and so what we recommend going forward is that we improve the digest two algorithm and we also think maybe we could just wait a bit and that will help that's all I've got thank you so the question was if you could get a telescope at one of the grunge points and so you could then have something that is observing both from here and from there and you get some sort of parallax and trying to better identify the orbits yes if you've got the money let me know yeah yeah sure so question is what the nearer of object follow-up community looks like it varies it's a lot of different people some like amateur astronomers have participated in this like the the list of things to follow up is public so there's lots of people out there there's also other things that there's like proper programs out there that collaborate there's no central authority it's mostly individual groups working together yeah but we we try to prioritize so that two people you know don't do the same one at the same time yeah sure so what does follow-up actually look like how do you how do you better constrain this orbit you basically just look at it for long so we're only like a couple of tracklets you have a fair idea of what the orbit is but you don't have a perfect idea but if you have enough on long periods of time all stretched out together then you can have a very clear idea of what the orbit is and make a strong statement for whether it's a nearer of object one yeah so is it roughly do non-conspiracy people actually worry about getting blown up by the asteroid yes yes I do absolutely like we've only just started testing out the redirect these things if something comes in right now we're you know it's not good something you know hopefully you'll sleep well still okay sure very confusing right but the size matters as well so if you're a really small thing you don't reflect much like a question but the size matters so if you've got something large and the namebells they actually can be much larger than things that you get close to the Earth they have a much larger area to reflect light back up the sun so they have branches in there it's also sort of a selection wise of you can't see the faint things in the namebell because it's so far away so you end up with one more time do not look at that I just want to say thank you again for coming out I'm Frank Castro my wife Shawn inside our homeowners so we've been doing this for a year now as a big person so thank you for being with us anniversary this is not the anniversary of our business but it's one year here with beer so we have a whole day planned on Saturday one but we want to thank you speakers for doing this monthly we're going to keep doing it so thank you very much for coming out and I hope you enjoy yourself I just want to before I release you I want to let you know that our next astronomy on top will be on May 31st that is the last Wednesday of May and who here was at our last astronomy on top in whatever month comes before April nice nice cool so you guys remember Bruce I found you guys so charming that he wants to come back and he's going to be giving an hour long talk that take up both the speakers loss so you will have something to look forward to with that have a wonderful night and we'll see you next month thank you because now to tell you guys