 Sam with Canada, Sam, have Jerry's sheets available. Thank you. Have your sheets, this one. This one, please. Thank you. How many we need? Two of them. Two of them. Two of them. Actually, you can just leave it on. I already have it. I'm like, look at that. Thank you, Rudy, for catching up. Good touch. I think I might need three things out there. Thanks to Cupgett tribute sheets and pencils from Sam up in the front, if you want to participate in trivia. The Milky Way and Galaxies Beyond. Yeah, that deserves more applause. The answers to the questions, after that, we will have our second speaker of the night, Zach Cohen, come up and tell us about the origin of life on the rest of us. I'm just kidding. I'm just kidding. Okay, so here's how trivia is going to work. The first question and all the questions after that, I'm going to leave them up on seconds apiece. Questions, I'm going to go all the way back to the beginning and show you every slide over again for 15 seconds apiece. So you'll get two chances in case you miss any questions. And if you haven't gotten a trivia sheet and you want to participate, you can always come up and get one from us at the front. It's everybody ready, 30 seconds apiece. I know that from the homework, because I was in Galaxia. Did I really do it for 30 seconds every time? That's crazy. I was thinking this seemed so long. Oh, that's cool. You can do more gifts. I like that. First things. Not a chance. No, I just said we're married. I didn't think that. I might have put it in the trivia sheets. Oh, okay. It's got to be like the most. It depends on what you do. Yeah. And he's playing along. Okay, one of these is it. I would kill this trivia. I wasn't brought from this trip. Trivia sheets at this time while we switch to the first speaker. Can you please bring them up front to Tyler? Okay, I'm going to switch this for you. Actually, you should probably. What am I doing? I can't help you. I can't help anyone. I can't help you. I'm going to switch to the first talk. So at this time, it is my pleasure to welcome our first speaker to the mic. Sam Garza in the astronomy department at University of Washington. She's working with Dr. Jess work on different galaxy stuff that she's going to tell us about today of our astronomy on top crew that runs the trivia. Okay, well, thanks for the introduction. I'm super excited to talk to you guys about galaxies. I love galaxies so much. So the title of the talk is Milky Way to the Milky Way and galaxies beyond. But before we get started, I just want to point out this awesome Milky Way picture that we have here. It's actually taken at the very large array in Socorro, New Mexico. It's run by the National Radio Astronomy Observatory. And besides the beautiful picture of Milky Way, which we'll talk about for the rest of the talk. That organization plus the National Astronomy Consultative is a main reason for why I'm an astronomy in the first place and why I study galaxies. So it's a super important part of my origin story. I just wanted to highlight them. Anyway, let's get going. I was too savvy. Okay. So the main question that I want to use to frame the rest of this talk is where in the universe are we? Now, I don't want to cause any existential dread or anything. Like, I know it's on Wednesday night or whatever. But it's a super important question that we talk about in astronomy. And it's something that we are still researching today. And hopefully at the end of this talk, you will know where in the universe we are. So you could answer that question. Just say Sam, we're at Bickersons. Okay, done. We're at the top. We're good. But I was not just thinking that. I was trying to think a little bit bigger, something maybe on this scale. So here's us, right on the earth. It's pretty cool. But we're not just in Seattle or even America for that matter. Let's zoom out. We're on a space rock floating in nothingness. Okay, that's making sense. Infinite nothingness for that matter. And that infinite nothingness is expanding. Okay, that scares me a little bit. But all jokes aside, this is kind of the starting point that I wanted to use for the rest of our talk. And we're going to keep zooming out to answer our question of where we are in the universe. But that's kind of a really big question. And so the way we can break it down is first think about where in the galaxy we are. Because I like galaxies, and I'm going to force it that way. We keep zooming out. Here's us. A lot of us know that we're the third planet away in a solar system that orbits a star called the sun. And if you keep zooming out, you'll see that our nearest neighbor is Alpha Centauri. It's that triple system over there. But it's not important. Stars, they're cool, but we don't care about stars. But what we mainly care about is this bluey purpley green thing that's on the screen. It's kind of faint in here. But basically I'll circle it. That's what we call the interstellar medium, or the ISM. It fills up the vacuum of space. It's about 90% hydrogen, and helium, and about 10% dust grains. Dust grains are annoying, but really cool. But they're mostly most of the carbon and hydrogen compounds. And if you build up a lot of that interstellar medium and kind of bound it together with those pesky stars, whatever, and make them bigger, you can get to a galaxy. So we answered a question. Here's the last. That little yellow star is the sun. That's our position in the Milky Way. We're about 26 light years away from the center of the Milky Way. And you might be thinking, great, we answered it. No. You might be thinking, Sam, how do we know we're in a galaxy? You just told us. You didn't prove it to us. And for that matter, what is a galaxy? We didn't answer the question. So I'm so glad you asked. So the way I thought that we could answer these questions is these handy-dandy timelines. So if you were dragged here by a friend and you're like, I don't like science, here's some history for you. And if you like science, I'm sorry, just stick with it. OK, it's going to go really fast. But my first point in my non-comprehensive view of the discovery of galaxies and getting to know that we're inside of a galaxy called the Milky Way starts in 1610, our boy Galileo Galilei. He was like, wow, there's a telescope. Let me use it. And he found that the bright band of stars and stuff that we've been seeing on the sky is actually composed of small little things, those pesky stars we've been talking about. And this is really, really cool because it kind of oriented ourselves from just, hey, we're on Earth, whatever. But now there's a bigger structure that we could possibly live in. There's other objects out there. And maybe there's more to this universe thing. So next came Emmanuel Kant. You're like, what? He does astronomy? But he did just a little bit. And so in 1750, he was like, whoa, what if? What if? Hold on. This thing that we're seeing on the sky is actually a rotating disk of stars held together by gravity. And those little other fuzzy patches, maybe we've been seeing on the sky with also that new fangled thing called the telescope. What if? What if? They are also galaxies. And they're maybe not a part of this world. So he's kind of the first one to start thinking about this. And people are like, eh, who knows? Here's a philosopher, whatever. But we kind of stuck using the telescope, observing more things. And we got to our guy in 1774, Charles Messier. He looked at more of these fuzzy patches on the sky that are kind of distinct from his bright band on the Milky Way. And he was like, ooh, I'm going to publish 45 of them. And nowadays, we know that three of those are actually galaxies, which is pretty cool. And then now we have this idea, OK, maybe we are in a galaxy. It's a rotating disk of stars, gas and dust held together by gravity. What if we got a better understanding of what this thing is we see on the sky? So that's happened in 1785, William Herschel and his sister Caroline. They were like, let's study it really quickly. So they looked at through their telescope, and they mapped individual stars. And they got this image here, which is our best understanding in this time of what the Milky Way looked like. And that was our best understanding for a long time. And we jump a super long way in history. And we get to 1922. We jumped a lot. But basically, that was the main idea that we had until we got to this debate. We call it a great debate. It really wasn't. But it makes it more fun. But basically, there was these two guys, what if the Milky Way is all there is? And these fuzzy patches we've been kind of floating around are part of the Milky Way. And the other guy was like, what if they're not? What if they're their own separate things? And so they couldn't really have an answer to that until the hero of the story, Hubble, comes along in 1923. And he used Cepheid stars as just another type of star. They kind of vary in pulsate. And they're super good for calculating distances. So you observe them and was able to calculate the distance from the Milky Way to the Andromeda galaxy. And this is one of the biggest scientific discoveries in the 20th century. It was the largest distance ever calculated to date, up to that point. And he proved that these fuzzy patches are not part of the Milky Way, their own separate thing. So now we have an idea that yes, we're in a Milky Way, gas and dust stars bound together, and that there's similar ones like it also out there. And so the next logical step is to really get a better understanding and further our ideas passively and crucial in a sister Caroline's ideas and map our own Milky Way. So that happened in the 1950s to 2008. We were using the newfangled radio telescope to observe 21 centimeter radio signals from the hydrogen that's in the Milky Way. Remember I said it's mostly made up of hydrogen helium, 90% of that interstellar medium. So that's what they were observing. It's better to use radio telescopes because there's that pesky dust that I mentioned. And if you use other parts of the electromagnetic spectrum, it actually absorbs it and you can't use it. But radio signals cut through that dust and you can actually map out the arms. And here's what some of that data looks like. Just orient you. This is kind of galactic longitude and longitude space using the radio data. And you can kind of start to see some wavy arms that we might be thinking are part of a spiral, part of a square galaxy, like that artist representation that I showed you from before. And why I'm showing this other than it's super cool is I actually did some galactic astronomy research when I was an undergrad. And so here's some of my data. And it was, hey, excuse you. This is the middle part of the inner arms of the galaxy. This is the near and far three kiloparsec arms. And so I was using those little hydrogen clouds within the disc of the galaxy to map where they are. And I used a model to see how it looked. And basically in a lot of artist representations, it kind of looks like a circle. But in my data, it's more oval. So you heard it here first. We have an oval football shaped inner side of the Milky Way. But anyway, so hopefully, now with my history lesson, I hope it's over. You can know that we're in a galaxy. We kind of get a better understanding of what our galaxy looks like and there's other galaxies out there. So now we can go for it. It's time to play. Is it a galaxy or not? So this is going to have some participation. I need you to play. Otherwise, it's not going to be fun. But we have two rounds. Hopefully, if you get to win, I mean you get bragging rights. That's about it. But here we go. Round one. We have two options. One and two. What is it? The number one is a galaxy. Hell yeah. Anyone for two? Two. All right. We've got a couple. Okay, okay. Here we go. And the answer is what hell yeah. You guys got a right? So this is M51 of the Whirlpool galaxy. This is my favorite galaxy. Just FYI. It's super pretty. It's got a nice spiral structure. It's very similar to the Milky Way, which is why we like to study it. If you answered sadly wrong, this is M80 of globular clusters. It's not as fun of a name. But this is actually a part of the Milky Way. It's one of the densest globular clusters. And it's made up of hundreds of thousands of stars. So it kind of looks like a galaxy. But it's not sadly. So we have our last round. You get to either keep your title or maybe try to win. You don't know. Okay. Here we go. Three options this time. So who thinks number one is a galaxy? Okay, nice. A couple he is. Number two. All right. Number three. Yeah. All right. All right. Nice. All right. I know I was really tricky and mean. And you're going to be like, Sam, you didn't tell us that there was multiple types of galaxies. That was really rude. And all I can say to that is, let me tell you about them. So we're back to our timeline. I swear this is the last history one, but it's a really important part of history. You have to talk about it. 2022, the James Webb Telescopes Deep Field Image came out. Or 233 History. But what's super awesome about this is the follow-up to the 1995 Hubble Deep Field Survey. And if I bring it up and make it a little bit bigger, every single one of these objects besides the lens to have a little pointy spikes on them, those are from diffraction things from the telescope, every other object in there is a galaxy, which is amazing. I'll never be out of work. But what's really cool about this is you can have your own talk about the many things that are happening in this image. And what I like to say about it is if you're standing here and you take a grain of sand and hold it at arm's length, that's how much the sky this image is, which is ridiculous, blows my mind. But you can kind of see that there's, there's different types of galaxies here, and they have all different types of morphologies, which makes galaxies super cool, and we can talk about those classifications. So we have to bring up Edwin Hubble's classification scheme. I hate this, but it's classic. We got to bring it up. But basically what it says is that we have ellipticals on one side, which are one type of galaxy, and they kind of break off into two different types of spiral galaxies, whether they have a bar or not. He originally thought of this for as much information as he had, and he thought that galaxies formed and evolved from the left side to the right, from ellipticals to spirals. We actually know that's not true. We kind of think that galaxies move the other way. They go from spirals to ellipticals, and that's because of the way that, and the stars that are in these galaxies. Spiral galaxies have more blue-y colored stars that usually indicates that they're younger, more star-forming. And then elliptical galaxies are like yellow-red footballs, and so yellow-y red stars are much, much older in their evolution. So we moved to the side. We can talk about the three different ones. We already kind of said them, but elliptical, they're considered early type, but that's just because of the old idea that we thought that we moved from elliptical to spiral, but we usually, we actually moved from spirals to elliptical. Then we also have a spiral, subdivided by if they have a bar or not, and then we also have irregular galaxies. They're kind of rarer, but they do exist, and that's why I don't super like this classification system because they don't fit the irregular ones in, but they do exist. So if we go back to our quiz, there is a different classification. So we have our elliptical, the spiral one, and the irregular. So hopefully, now that we don't feel like I tricked you too much, we've learned that there's different types of morphologies for different galaxies. So we're back. Back to our original question of where in the universe are we? And finally we've answered the question, we know we're in a galaxy, and hopefully we know what is a galaxy. And so we can actually even classify our own one. We have, it's a barred spiral galaxy, and actually it has a supermassive black hole at the center, which I didn't mention this before, but a lot of galaxies do have supermassive black holes at their center. So let's keep moving out and finding out where we are in the universe. So if we keep zooming out, we get to this beautiful reservoir of gas. It's called the circumgalactic medium. It surrounds in the environment of galaxies. Super interesting. You have some gas that's coming from outside of the galaxy and moving in that's creating gas in blue. You also have different processes within the galaxy, maybe supermassive black holes, maybe supernova going off, stellar feedback pushes gas out, and also that gas gets pushed back into the galaxy. And that's recycling gas. And the entire gas that's really surrounding this galaxy is very diffused. So it's super hard to study. And a lot of questions can come from this. We have, I don't know, you can have a whole talk about the circumgalactic medium, like what is the origin of this gas and how does it play into the different morphologies of galaxies? What is the migration route patterns? Do stars and supermassive black holes affect the galaxy evolution? And how does an evolving galaxy kind of evolve in a moving universe? Well, because I have your captive attention and it's me. I actually study how supermassive black holes affect the galaxy evolution in relation to the circumgalactic medium. So we're going to just do a brief aside on what I do as a scientist. So we're going to move to cartoon land again. Like I mentioned before, the circumgalactic medium is super debused and really, really hard to study. But we do know a few things about it. One, that it is a gas, so it contains a lot of different similar things to the interstellar medium. And remember I mentioned that there was a 10% dust grains and it kind of had hydrogen carbon compounds. That's something similar that we see in the circumgalactic medium as well. And one of the main things that you can study is the carbon ions. And so that's the mention, like the little Pac-Man guy that was sitting in there. So there's a circumgalactic medium around our Milky Way and also other galaxies, which is the blob up to the side. And so using the fact that there are these carbon ions in the gas, we've devised a kind of indirect way that we can observe the CGM. And we do that by using a quasar or a bright background source. Quasars are usually the best kind of object that you can use. They're basically just like a cosmic flashlight. They just spew out energy. They're really cool. They're just doing their thing. But basically they spread out that light all the way to an instrument. So we like to use spectrographs because they're really nice and they can catch the little features that we want to see. The main one that I use is the Hubble Space Telescope that has the cosmic origin spectrograph on it. So that's indicated by the bottom line. And so the light comes from our quasar, passes through different CGMs of galaxies and also the Milky Way. And so what it does is those carbon ions kind of make absorption features as the light passes through. So you can kind of think of it as the Pac-Man eating our light source and causing these little dips in it. But let's move past cartoon land and see some actual data. So this is from a galaxy that I study. We've been talking a lot about up the Milky Way, but I study other galaxies that are nearby. So you can kind of think of the squiggly line as our rainbow line that was in the cartoon. The amount of flux or the y-axis is basically how much light is coming to our detector. And then the dips are what the carbon ions do. They're these absorption features as they eat out the little spectra. And so what makes my work tricky is that it's really hard to observe these galaxies in the first place. And then you move them farther away from us and it makes it even harder. And then you also have the light passing through the galaxy but also the Milky Way. So it just contaminates my data. It makes my life hard. And then I can take out some of the Milky Way's stuff. And so that's that gray band over here. So all that absorption is Milky Way. I don't care about it. What I care about is this pink line. How much carbon are we seeing? And so basically what I do is I calculate the area of the dip because the dip can tell you a lot about how much carbon is in there and that you can start making different inferences. And if you do that for a sample of galaxies you can get something that looks like this. So now you're going to be like, Sam, how does the aggressive black holes fit in? I'm talking about carbon. Let me tell you. So basically what I do is this y-axis is how much carbon I'm seeing versus how far away my little flashlight is away from the galaxy. And so all of my data are the little points, little dots. And what I'm trying to do is compare what I see to simulations. So the simulational data is the lines that you see here. The differentiation between the two is I've split the sample into if it has a high mass of supermassive black hole or a low mass of super black hole. So the high mass ones are the blue ones or the top line and the low mass, excuse me. Low masses are on the top, high masses are on the bottom. And the main takeaway that you can get from this and it's super fast is they don't line up. We don't have the dots. The dots are not fitting with the simulations. So TLDR, maybe supermassive black holes don't impact the CGM as much as we thought. This is still super preliminary. I haven't got all of my data yet. But this is currently what I'm working on. And it's super important to kind of figure out what these supermassive black holes do actually observing them, because these simulations don't just do what I want them to do. They're input in a lot of different, other different researches. And so if you don't have a right parameter for the simulation, it can affect a lot of other people's research. So it's good to track this down and make sure that everything's working correctly. Okay. We're done with my aside. We're good. Back to our main question. So if you keep zooming out from the galaxy, this is where you get. This is a local galactic group. So galaxies don't just live by themselves. They're friendly. They're neighbors. So you can kind of orient ourselves and think of this as the neighborhood of the Milky Way. We have some fun, famous neighbors as well. We live with celebrities here. We have Andromeda Galaxy. I'm sure you've heard a lot about her. She's about 2.5 million light years away from us. We also have the Triangulum Galaxy and maybe the small and large Magellanic clouds. They're really cool. I've never seen them. That's a life goal of mine is to see these galaxies. So basically this is where we are. If we keep zooming out, because we don't just live in a neighborhood, right? We live in bigger places. We live in a city. So if we keep zooming, this is actually what we call the Virgo supercluster. It's kind of hard to see in here. I'm sorry about that. But basically you can think about this as, this is a supercluster. So a cluster is equal to in our city. And the Milky Way is kind of right in the center. Super hard to see. But this is our city. So we can think of maybe the Milky Way as Ballard. I don't know because that's where we are. Our other neighbors are the Virgo superplucks, the Fordax, Coma. There are all other different neighborhoods. I don't know. Maybe U-District, Capitol, et cetera. But we don't just live in neighborhoods, right? We live in cities. We live in states. So if we keep zooming out, we get to our final destination of the Virgo supercluster. So that's our cluster through galaxies. Our city is surrounded by other cities or other superclusters. So this is kind of like a large cosmic web that is the universe. And so galaxies don't just look by themselves. They're clustered together. They're moving away and towards each other. And they create this big spiral everywhere. And so our last zoom out, hopefully, because our last ending point, our final destination to answer, where in the universe are we? And we got to zoom out pretty far. We're still going. Okay, here we go. So this is our final destination point. This is Laniakea and measurable heaven. This is a fantastic data point that came out in about 2015. It's just beautiful. You can see that cosmic web that I've been talking about, these movement of galaxies. All of these points in here, each one is a galaxy. So it's incredible. And this is just kind of our disrepresentation. But if you want to look at some actual data, this is the Laniakea structure set in supergalactic coordinates. You can kind of just think about it as longitude and latitude. But basically, what was super interesting about this research, other than we got a better understanding of where we are, what they did, this is Brent Telley at the University of Hawaii. They took the motions of all the galaxies that surround us and mapped them on a scale that had never been done before. And what it did is it gave us a clear definition of what superclusters are. We didn't really have that before because we kind of just had observed that we didn't really know where one supercluster ended and when it didn't, it was kind of just all arbitrary. But now because of this research, we do have a definition and you can kind of see where the supercluster ends and begins. So on the left-hand side, the black is the verbose supercluster, so where we live, kind of our city of Seattle. And you kind of think of the red one as our mirror body supercluster, maybe, I don't know, or Clint, whatever. But you can see how they kind of diverge at that central point and they were able to calculate that through the motions of the galaxy. And so we finally had a definite understanding of where these things were in the universe and where we fit into that. And so the main point was, Belania Kea is just a small part in the cosmic web in our universe and we finally have that clear definition of what superclusters are. And so leading with this, that little red dots us. And so it's crazy to think that at the beginning of this talk we started with us in Biggersons on a small floating blue rock in a solar system in a galaxy called the Milky Way. We live in a city or supercluster called the Bergo supercluster and finally our destination of land in Kea. So thank you for taking this journey with me and I'm happy to take any questions. 36, let's zoom back. I have a lot of different transitions. I don't know if we can do this. Yeah, so the question is like, you have to take into a lot of different factors and you have to worry about the noise in the data is what I'm understanding. And so maybe that's also playing into models and you're totally correct. So this data gets reduced by the Hubble Space Telescope team and so that actually does factor into my idea. This data is super, super wonky. One of my friends, Bo, is actually here. She does Milky Way spectra and I'm always jealous of her spectra. It's so pretty. Mine just looks like a carbon over it. So we do take that into account and these models can change depending on what type of fitting program you're using. So we're pretty sure that this is what area we're calculating but yes, noise does affect it. But it would be kind of minuscule compared to how different we're seeing from the simulations and so we're really considering that maybe it's more on the simulational side but this is, again, stupor preliminary and I'm still working on it. But that's a good consideration. I don't know if there's no questions. That is good to stand here and look pretty. Ooh, what am I looking for most in what's coming out with galaxies? I gotta say anything with JWST. So I work mainly with nearby galaxies and they're all at a very nearby redshift. So not even more than one. But what I'm super excited about with database T is when we're looking at high redshift galaxies because because we can see so far with JWST this is gonna change the type of physics and understanding of early formation, early evolution of what's going on and you can even study the CGM of these early high evolution galaxies. So I just got to meet a postdoc who works on the stuff so I'm super interested to collaborate with her but I would say definitely anything to do with database T and high redshift galaxies. Yes. What about the curved lines? Oh, the curved lines. So the question is that each dot in linear k as a galaxy can actually zoom back. The curved lines are more talking about the motion and where those galaxies are directed towards. So I didn't get to go into it much but there are different parts of the linear k that a lot of galaxies are moving towards. There's actually one called the great attractor and so we think of everything in the universe kind of expanding and moving away from each other because gravity does play a part in things because gravity is really strong. So in addition to everything expanding away from each other they're kind of co-moving as they move towards something and that's what those lines are kind of indicating. So that kind of big dot on the side is all those galaxies moving towards each other and kind of create these streams of movement towards that. So there are dots kind of moving towards that mini stream and then all that's kind of moving towards the other part of linear k. You have time for one more? Wait in the back. How does the observable universe compare to linear k? How is it relate? Well, this is all part of the observable universe. So this is a simulation. These are actual real galaxies all moving towards each other. So this is all not, I mean relatively nearby but I'm not sure how much on the cosmological scale it would be. I'm not a cosmologist. We do have one here. I saw him earlier. There he is. So I would bug him. But yes, this is all observable galaxies that we have real data for. That's why we got this image. There you go. It's still tiny. You have to hear folks from a real cosmologist. This is real tiny. Well, thank you guys. Well, that was fantastic, Sam. Thank you. And I saw that really awesome cartoon drawing with the Pac-Man and stuff. I just wanted to point out, Bo, do you want to stand up for a second? Bo is the artist that created that. I love embarrassing my friends. I really do. Okay, so now I'm going to announce the trivia answers and then I will announce the trivia winners. We have two winners today. One of them got nine answers right and the other one got eight answers right. We had about a million people get seven answers right. So if you guys weren't all so good, maybe there would be a third place but there's not. So I'm going to now tell you the trivia answers. In the Orion Cygnus arm of the Milky Way, I'm pretty sure it developed the grindstone model of the Milky Way. The orbital speed of our solar system is about 200 kilometers per second. The nuclear bulge contains the highest density of stars. That would be the middle part. The candy bar in the Milky Way is not named after our own galaxy unfortunately. I actually didn't know this. Sorry, I'm reading this. It was after malted milk. That's cool. Okay, there are about 800 planetary systems. We recently like last year sometime broke 5,000 discovered exoplanets. So that's cool. I say we like I had anything to do with it. The ribosome produces proteins in the cell. I knew that. What organelles are only found in plant cells? That would be chloroplasts, cell walls, and large vacuoles. And it is false that the RNA, I'm not even going to try to read this. You guys can read the question. And the most important parts of a cell for an astrobiologist is the membrane DNA and the proteins. And I'm sure our second speaker will explain why that is. Okay. Are you ready to hear the winners? Yes. Second place, but you guys are all getting the same prizes anyways. It doesn't really matter. Second place with eight answers right is milk people. And first place bragging rights with nine answers right is Marshall. Congratulations Marshall. Okay. So if you are one of our two trivia winners for this evening, please wait until after our second talk is complete to come get your prize. So do not come now. Okay. So with that, we are going to take a brief five to 10 minute intermission so everybody can get more alcohol and hot dogs if they want. And after that intermission, I will bring on our second speaker. Thank you. Second and last speaker of the evening. I am about to bring up here in a moment is chemistry department at University of Washington working with Sarah Keller. And he's going to be telling us today about how the origin of life on earth informs our search for alien life in the universe. So without further ado again, Zach. Thanks Megan. Thank you guys for sticking around. I know it's freezing right now. So I really appreciate that. Yeah. So like Megan just said, I am a chemist. So thanks for not, you know, booing or throwing tomatoes. I appreciate that. I know this is astronomy on tap. But really I have a shared goal with my astronomy friends, which is to determine if there could be alien life beyond earth. Doesn't necessarily need to be little green men. Could just be a microbe on a different planet that would still be extremely, extremely exciting. So my approach is different from most astronomers. I want to know, given a set of planetary conditions, can life originate? So the origin of life is the natural assembly of nonliving material into life. So that could be minerals, water, organic compounds, energy, any nonliving material going to life. Now, surprise, surprise, earth happens to be the only place that we know for sure has life. So even if we want to understand the origin of life in general on some, you know, fantastic exoplanets, it makes a lot of sense to start by thinking about the origin of life on earth. So let's talk about the history of life on earth. We know that very early in earth's history, there was an extremely large asteroid impact. And this basically shattered the surface of earth. And some of that debris went on to form the moon. So this is called the moon forming impact. So scientists can calculate that this was an extremely energetic event, enough so to melt the surface of the planet. So we're talking, you know, molten rock. So I think it's pretty reasonable to say that if there was any life on earth before this, there wasn't after. This was a sterilizing event. So at this point in time, earth is lifeless. But relatively shortly after in earth's history, we know that earth is inhabited with life. So this is the oldest evidence that we have for life, these little mounds in the rock record. And what these are are called stromatolites. And you can actually see stromatolites on modern earth today. They're these mineral mounds that form as cyanobacteria grow and do photosynthesis. So this is the oldest evidence for life. And it tells us that at this point in time, earth is inhabited. And since then life has diversified in a number of amazing ways. We've got all sorts of people and dogs and fish and plants. And so we actually understand a lot about how we went from the oldest life to modern life. Now you might say to me, going from a bacteria to a human, that is amazing. That is just unbelievable. But we do have a good sense of the key transitions that have to happen to go from here to here. What we know much less about is what happened in this period. So this is probably, if you're going to stop listening to me right now, this is what you should remember, is that the origin of life on earth, how we go from a lifeless planet to a living planet, that is actually still a mystery. And it's one that we need to do more research in order to decide. So here's my plan. I'm going to tell you guys about some theories for the origin of life on earth. I'm going to talk about which earth environments the origin of life might have occurred in. And I'll tell you what that means for alternative origins of life elsewhere in the solar system. So for the first part, for the most part today on earth, life is made of cells. So our bodies are composed of trillions of different cells and many cell types that you've probably heard of, like neurons and white blood cells. And we can look into the microscopic world and see all sorts of different single-celled organisms. Now, there's one debatable exception to this rule that life is made of cells, and that's viruses. It's debatable whether viruses are alive or not, but it doesn't matter because I just don't want to talk about them. If you're anything like me at this point in time, you're kind of sick of talking about viruses. So we're just going to go with this generalization that for the most part today on earth, life is made of cells. And that leads us to our next question, what is a cell? If there are any biologists in the audience, I'm now ready to offend you by saying my very simplified view of a cell is just as a bag of chemicals. So there's three key components in this model for a cell, a bag of chemicals. The first component is the bag itself. In chemistry speak, we would call that a membrane. So this forms the boundary of the cell. Here's a microscope picture that I took of a membrane. The second component is DNA. So DNA stores the information needed to replicate a cell, and it does that with this sequence of A, T, C, and G. And the third component are proteins. So proteins use the information in DNA in order to enact the replication of a cell. So here is a beautiful microscope picture that I didn't take of a dividing cell, and they've stained a protein in green, and you can see that it's working to pull this cell apart. So that's just one role proteins can have in enacting replication. Now, in order for the first cells to form, we need two things. First, we need sources of these three components on the early earth. And then second, we actually need those components to assemble into a cell. So let's start by talking about the sources. The first source of cell components on the early earth that I'll talk about is delivery by meteorites. So these chemical components can actually get synthesized while this meteorite is out in space, and then the path of the meteorite happens to intersect with Earth, and it happens to land in the ocean or in a lake, and those organic molecules, these chemical components, can dissolve out of the meteorites and potentially assemble into a cell. Now, we know that meteorites can actually deliver molecules that assemble into membranes. Meteorites can deliver the pieces of proteins, so that's what I'm showing here as a green ball. That's one piece of a protein, and remember that a protein itself is just a chain of its pieces that folds into a particular shape. So meteorites deliver the pieces of proteins, and meteorites deliver some of the pieces of DNA. They actually deliver more pieces of a similar molecule called RNA that I'll talk more about later. So meteorites deliver all of these cell components, and that's not just theoretical. That really has happened. We have a rock, falls from space, contains all of these components of cells. Kind of amazing. The second possible source of cell components on the earlier is lightning. So this idea really took off from this Miller-Urie spark discharge experiment. So in the 1950s, Miller took some gases that he thought might have been available in the Earth atmosphere. He put them into this glass flask, and he shot electricity through it, and it turns out he made all of these different components of cells. He made molecules that can assemble into membranes. He made the pieces of proteins, and he made at least one piece of DNA and of RNA. So this Miller-Urie experiment was very important, because it really showed scientists that we can learn about the origin of life, this ancient process, by doing lab experiments. Now, even if we had all of the components of cells, how would they actually assemble into a cell? This fundamental problem is kind of a chicken and egg problem. So if we know we need the information in DNA in order to make proteins, but proteins are required to make DNA, you can see the chicken and egg. How did this whole system get started? That's the question. So the first theory that tries to reconcile and solve this paradox is called the RNA world. So in the RNA world theory for the origin of life, there's one single type of molecule, that's RNA, that can store information like DNA does, but it can also enact replication like proteins do. Now, RNA is less effective at both roles than DNA or protein, but nevertheless it's capable of both. And so that makes scientists very excited about the prospect for an RNA world. So here's some data, some real data that I collected that suggests that this actually is possible. So what we're looking at here is a piece of gel with an electric current running through it. And so that's going to separate small, unreacted RNAs from big RNAs. And in this case, this RNA has actually grown itself. It's taken another RNA, so the RNA isn't red. There's another black RNA and it's stuck it onto itself. It's increased its size. So you could think about this as like the first step in enacting its replication. So this really can happen. It can use information in order to enact replication. Now, there's reason to be skeptical about this RNA world idea. So I mentioned briefly that meteorites and lightning cannot supply all of the pieces of RNA. There's a set of simple chemicals that have been identified that could have been available on the earlier and has been demonstrated. You can convert that into pieces of RNA using this series of reactions. Now, each reaction can be done individually and it requires an experimenter to prepare the products of each reaction for the next reaction. So it's unclear how this would have happened on the early Earth. And this has led a famous origin of life researcher to make this analogy for this kind of chemistry, which is that of a golfer who having played a golf ball through an 18-hole course, then assumed that the ball could also play itself around the course in his absence. So that's an analogy for this kind of chemistry, imagining that that might happen on the early Earth. So, like I said, there's reason for skepticism here, but this ability of RNA to play both roles as store information like DNA and enact replication like proteins do, scientists really can't let that go. So, some people have said, okay, RNA is great, but maybe we need more than RNA. Maybe we need RNA and proteins. And so that leads us to theory number two, the RNA-protein world. So I would say that there's two pieces of evidence for this theory. The first is that direct physical interaction between RNA and proteins actually stabilizes both molecules and could have allowed them to persist in the early Earth environment. So hopefully you guys can see these two graphs. This graph is RNA stability on the y-axis and this graph is protein stability on the y-axis. And in both cases, the stability is highest when we have RNA and protein together compared to RNA only or compared to protein only. So that's one piece of evidence. The second piece of evidence comes from the ribosome, as you just heard about during trivia. I'd possibly know them up before. So the ribosome is a very important part of cells that I didn't mention before. It's found in all modern cells and that suggests that it could have been available. It probably was present in the last ancestor of all cells, could have participated in the origin of life as well. The ribosome is made of protein and RNA directly. So these pieces of evidence make us think RNA and protein are important. Now theory number three is different. So this is a theory that's gotten... a lot of work has been done at University of Washington specifically and we start with the observation that membranes actually are very easy to form and they form just based on the shape of this membrane-forming molecule. So this molecule has a head group that likes to be oriented towards water and a tail group that likes to be oriented away from water. So when we put them in water, we form a layer with head groups facing exterior water and an inner layer with head groups facing interior water. So this is a cross-section and in 3D, you can imagine it kind of looks something like this. And if you cut through this sphere, we can see that the membrane is separating the exterior water from the interior water and this interior space you can think about as the inside of a bag. So this is where we get the idea that this is a bag. Now what we've seen at University of Washington is that pieces of RNA and pieces of proteins can actually bind to these membranes. So here's a very simple experiment that shows that. We can mix up the pieces of protein together with membranes and flow it through a filter. So the membrane is relatively large. It can't flow through this filter but the pieces of protein are small. They can flow right through. When we actually do the experiment though, what we see is that some of the pieces of protein are retained up in this top compartment with the membrane and that suggests that they're physically bound to the membrane surface. And this binding could explain how RNA and proteins ended up in the same place as membranes during the origin of life. Now theories 1, 2, and 3 converge on a similar idea which is that of a protocell. So in our protocell we have RNA storing information like DNA does. We have RNA enacting replication like proteins through acting like protein. We also have proteins acting like protein to stabilize the membrane and stabilize RNA. Now we have some idea about how the membrane parts of the protocell and how the RNA parts of the protocell can actually reproduce themselves or be reproduced in the environment. If we have variation in our protocell population that causes some of these protocells to replicate faster than others, then those ones that replicate fast can quickly come to dominate the population and that's an example of evolution and in my opinion evolution is a defining feature for life. So this is really an idea and a pathway for how we get to life and to cells. Now this field is filled with alternative theories. One of those is saying, okay RNA we don't know how to make it, we don't know how it could be present on the early earth, therefore it must not have been, we need some alternative. So people look for similar kinds of molecules that can base pair and form helical structures like DNA and RNA do. So that's one set of theories and the final theory that I'll talk about is called metabolism first. So metabolism refers to all of the reactions that a cell can do. And if we look at any two chemicals in our metabolic path, in our metabolic network, we can see that they're separated by this arrow and that arrow means that it takes an enzyme to convert between any two chemicals. So an enzyme is a protein, it's a catalyst, so it's going to make this reaction faster or couple it to a more energetically favorable reaction. In metabolism first theories for the origin of life, researchers look for subsets of this network that can function without enzymes. And so this is extremely attractive. We don't need enzymes, we don't need RNA or DNA. This would be very compelling if we can do this, although it's hard to imagine how this non-enzymatic network leads directly to life, but nevertheless this is a common idea in the field. Now whatever origin of life theory we prefer, we know that it has to converge on our bag of chemicals model for a cell with membrane, DNA, and protein. The reason we know that is because that's what all modern cells have. It's pretty reasonable to assume that the last universal common ancestor of all cells, of all life, also had this kind of cell. Now, so if your head is spinning at this point, it's maybe not unexpected. None of these theories that I'm talking about are complete theories. There are gaps in our understanding of all of these theories. This is why the origin of life is this great mystery. We don't have an answer to it yet. We need more research in order to understand it. So what's the best way to continue to doing research on this topic? I think one important question we can ask is in which environments on Earth could the origin of life have occurred? The first environment that's got a lot of traction from origin of life researchers are shallow lakes or ponds that can evaporate. If we imagine we have some cell component dissolved in lake water, as water evaporates, the concentration of that component is going to increase, and that's good for building a cell. Eventually, we imagine complete dehydration during the dry season, and then flooding in the wet season, and we can go through cycles of wetting and drying. It turns out that drying actually is good for building cells as well, because drying makes protein synthesis more favorable. We're going to have to dig in for a second. This is a real chemistry example. Here are these two green balls. These are two pieces of protein. Amino acids is the chemical name. We have two pieces of protein. They can react to form a chain of length two. Remember that a real protein is a chain of length 50 or 100. You can think about this as the first step to forming a protein. What we notice is that there's another product in this reaction, and that's water. It's a fundamental chemical principle that if we remove water, we should make more of our protein product. In our drying lake scenario, as water evaporates, we'll actually favor formation of chains of length two and chains of length many. It's a chain formation, and that's one reason why these evaporating lakes are compelling sites for the origin of life. The second environment that many people implicate for the origin of life are hydrothermal vents. These are places, for example, at the bottom of the ocean where water gushes out from the ground. In some cases, that water can have high pH. So relatively few protons compared to the surrounding seawater. This is an example of a natural proton gradient. We have a region with many protons and right next to a region with few protons. It turns out that cells use homemade proton gradients in order to store energy. A cell will eat food in order to create the situation where it has many protons on the outside of its membrane and relatively few protons on the inside. And then, using this sophisticated black tube a cell can take a proton from the outside to the inside and store energy in that way. So if, again, if there's any biologists in the audience, this is ATP synthase. And so this is how cells store energy. They use these proton gradients. Maybe primitive cells during the origin of life could have used natural proton gradients in analogous if they had a similar kind of black tube to convert this energy. So based on that, based on our understanding about environments for the earth origin of life, where else in the solar system or the universe might we expect life to be able to originate? What about Mars? So we have these beautiful pictures from Rovers showing us that Mars is extremely dry today. And that's probably not good for life, but there's evidence that in the ancient past Mars actually had flowing water on its surface. So here's a large canyon and a channel on Mars' surface that presumably were cut by flowing water in the past. Similarly we see these pebble-king glomerates forming in flowing water on the modern earth and we see the same kind of thing on Mars. So there's evidence that in the ancient past Mars had flowing water on the surface. It doesn't have water on the surface flowing today. So presumably in between there was a period of significant evaporation and that at least reminds us of our evaporating lake idea for the origin of life. So maybe there was an origin of life on Mars in the ancient past. Now what about the icy moons in Celadus or Europa? So if you're not familiar with these places, they're water worlds so a very deep ocean and it's very cold at the surface so it freezes into a thick ice shell and potentially at the bottom of that ocean are hydrothermal vents that could be supplying natural proton gradients that could enable an origin of life. Now scientists have done a lot of work to characterize the nutrient content of this ocean and it's very possible that this could be habitable. So if we dropped an earth microbe in there it's possible it could live and that's amazing. It doesn't necessarily tell us anything about the origin of life there so we need to do more research on hydrothermal vents in order to constrain the possibility for life on icy moons. What about Saturn's moon Titan? So Titan is cool for one reason because NASA is sending a mission there so we're gonna learn about Titan for sure. It's also cool because it's got these big lakes on its surface but it turns out those aren't lakes of water like we're used to thinking about. That is a lake of oil. So could we have an origin of life in oil? One way to think about this is to think about our membranes. So the membranes have water loving head groups, water fearing tails. We could similarly think about that as head group being oil fearing so we're certainly not gonna if we have oil on the outside we're certainly not gonna have our oil fearing head groups orienting towards that oil. Now you might think okay maybe these molecules can just reverse themselves and form like a reverse membrane but it just hasn't been seen in experiments on earth so as far as we know if there is and protein folding really works the same way so these fundamental chemical features of life would not work in oil environments and so if there was an origin of life and if there is life on Titan it's probably completely different than life on earth. Okay I'm just gonna wrap up so I think it's reasonable to say that if there's alien life out there it had to originate somehow. Now unfortunately we don't fully understand the origin of life on earth. What we do know is that much of life on earth is made of cells and we know that cells are just bags of chemicals. We have identified plausible sources for many cell components and that includes meteorite delivery and lightning strikes and we have many ideas about how these components can actually assemble into cells. One idea is the RNA world and another famous idea is metabolism burst. Woo. Getting windy. And so we also have a sense of the most likely environments on earth that life could have originated and I would say that's evaporating lakes and hydrothermal vents and based on our limited understanding of the earth origin of life, maybe I'll try to hold this. You know we have a sense we can guess about which locations in the solar system are the most promising to find life. And I would say that's Mars and the icy moons. So I think that's it. Thanks again you guys for listening. I'll take any questions. It's being delivered by meteorites. How is it being produced? That's a great question. So he's asking these chemical components that come to earth by meteorites how do they get produced? I think that's an open question. We have some sense of some reactions that might be participating but even though those reactions we have a sense of when they occur on earth for example there's a set of reactions called Fisher-Tropes reactions that we know sets of conditions where they occur on earth and for the most part it doesn't seem like those are the conditions we find on meteorites even though some of the distribution of products match distributions from Fisher-Tropes reactions on earth. So I don't have a good answer to that. It's a great question. It's an area that needs more research. Yeah, great question. So he's asking I think you're asking is there for sure only one origin of life? Or is it possible that there were multiple maybe simultaneous origins of life? I think it's very I don't know. Certainly I don't think anyone does. I think it's very possible that there were multiple distinct origins of life and maybe they just like modern bacteria can do they can exchange chemical information so maybe that happens these different types of life merged with each other. Maybe one outcompeted the other. It's a great question that I am concerned might be lost to history I don't know if we can ever learn that but maybe we can and it'll be really interesting. Yeah, that's a great question. So asking about viruses. So I mean one thing to say about modern viruses is they rely on host cells. So I certainly don't think that the origin of life was a virus the way we know them today. But parasites in general they are features of molecular evolution experiments in the lab and I think it's safe to say that there is always a role for some kind of parasites in an evolving population. So definitely I think different kinds of parasites could have been important and presence during the origin of cells but they must have been less sophisticated than modern viruses. But it's again another great question that I don't have an answer to about the origin of viruses really. I'll go back. What do we know about the chemical makeup of Europa's moons? Well I know that Lucas has done some work to constrain that. That's a great question. I think that people can estimate the kinds of salts and the pH of ocean water and suggest that it is in a range that's suitable for earth life. I think we have a lot to learn and we need more resources to go and measure things. Yeah. There's definitely people here who can give a better answer to that question than I can. But yeah I'd be happy to chat more about it. One more question. Okay I saw in the back that's a great question. So she's asking of the meteorites that we've seen fall to earth how many of them contain these chemical components? It's certainly not all of them. It's a certain class of meteorites called carbonaceous chondrites. There's many different meteorites that fall to earth that don't contain any of these. It is a small, I think it's about 4% of all the meteorites that we've observed fall to earth that actually contain any kind of organic compounds. Okay I think that's it. I'll stick around. Thanks. You can give that to any of them. Okay let's do one more round of applause for both of our fantastic speakers and thank you to Biggersons for hosting us once again. I just wanted to say that our next usher on tap will be here at Biggersons on March 29th. That's the last Wednesday of the month. Mark your calendars and speakers will be later announced on our social media. So with that I'm going to release you all. Please get home safe and thank you for coming. And if you won trivia come get a prize. I'm going to run and get a thought done. Will you keep an eye out? Thank you.