 Well, it's that time of the week again. It's time for Chitchat Across the Pond. This is episode number 770 for June 22nd, 2023. And I'm your host, Alison Sheridan. If you're a fan of the Big Bang Theory, you may remember when Dr. Amy Farrah-Fowler became only the fourth woman in history to win the Nobel Prize in physics. While that fictional show aired in 2019, in 2020, a fourth woman in real life actually was awarded the Nobel Prize in physics. I have the great pleasure of introducing you to Steven, my friend, Dr. Andrea Gez, as our guest today on Chitchat Across the Pond. Welcome to the show, Andrea. Thanks, Alison. It's a pleasure to be here. I've been dreaming about this so long that last night I won the Nobel Prize in physics. Awesome. I was marching around telling everybody, Nobel laureate here, Nobel laureate here. So, Steven, I've been lucky enough to hear Andrea give lectures about her work four times, once in Iceland and once in Antarctica, both while traveling through UCLA alumni. Go UCLA. Anyway, Andrea is currently a professor of physics and astronomy at UCLA. And I'm really excited to talk about your work, but I want to start us off with kind of a softball question that I asked you on one of the trips. What's the difference between an astronomer and an astrophysicist? Snob appeal. Well, when I was in graduate school, I used to say it's the difference on an airplane between a short conversation with your neighbor and a long conversation. And in fact, you could ask between physics, astronomy, and astrophysics. So the shortest would be physics. The longest is astronomy, and astrophysics is somewhere in the middle. So everybody thinks they understand what astronomy is. Well, aren't you? They've looked at the stars. Softball science. I like it. Well, in rereading your bio, I saw that your field is observational astrophysics. Now I've heard of experimental physicists and I've heard of theoretical physicists, but what's an observational physicist? How do the three of those play together? Well, in studying the universe, we can't do controlled experiments. So in many fields, astronomy, call it astronomy and astrophysics, so you can pick your flavor or geology. You can only observe the natural world. So that's why we call it observational astronomy. You can design your experiment. So you can talk about experiments, but they're not experiments in the traditional way in which you get to control and change the variables. So you do it by looking at different places. So that's what we call observation or an observer. Time and planets. You just hold still for a minute while I go to this other one. Okay, that's interesting. I hadn't actually caught that. Now you were awarded the Nobel Prize for providing evidence of a supermassive black hole at the center of our galaxy. Is that a correct statement? Yes, although if you look at the citation, it's very carefully worded. It's for the discovery of a supermassive compact object at the center of our galaxy. And I think it's always interesting to see how the Nobel Prize is described and curated. And I think it's a nod to the fact that while we've improved the evidence for these supermassive black holes by a huge amount, like a factor of 10 million, there's still room to get even better evidence. So they're leaving. So many people make that assumption and make that leap, which is she should interpret it as the discovery of a supermassive black hole, because it is the best evidence that we have today, but the citation really does leave an opportunity for more recognition. Oh, that's kind of cool. I like that. Well, is science, if nothing else, should be specific? Right? Yeah, this is. Very. So now my audience is pretty nerdy. I've run a more complex version of chitchat across the pond. This is the light version where we just discuss astrophysics. But can you start by explaining what a black hole is and what makes one supermassive and why is that important to us, the difference? So what is a black hole? You can start off with a really simple definition, which it's an object whose pull of gravity is so intense that nothing can escape it, not even light. So that's actually the definition. And then we're gonna talk about supermassive ones and, as you might imagine, they're really massive. And the reason we use that as the descriptor is that people thought about the idea of black holes that came from the evolution of stars. So they're roughly 10 times the mass of the sun. And the ones that we're talking about are almost a million to a billion times larger than that and hence the supermassive. The origin is quite different. At least we think it's quite different. So we think those kind of black holes reside at the center of a galaxy. So one supermassive black hole per galaxy is the... So it's not like there's a continuum of sizes of black holes and at some point you cut it off and say from here up. It's because they are formed at the center of the galaxy or vice versa, depending on your perspective, right? Yeah. Yeah, I mean, there's a gap. And in fact, people talk about the mysterious or elusive intermediate mass black holes because there's a big gap between those two. And today it's a big debate, but yeah, there's a huge gap in terms of the masses. So it's the debate that we haven't developed experiments that can have observed them. Like so we can't prove they exist, but that does mean not existing. Right. So it turns out for, it might... We haven't found one. So that's a true statement. And the question is, is that because they don't exist or because they're hard to find? That the techniques that people are using oddly enough are insensitive in this regime because actually kind of coming back to your original question about observational astrophysics, you have to look for the system that will reveal that kind of object. Okay, okay, interesting. Well, speaking of that, so there were theories that there were supermassive black holes or a theory that there was one at the center of our galaxy before you started looking or there wasn't? Oh, there were hints that these things might exist, but I would say the theories were not clear. So there was the notion that maybe these supermassive black holes do exist at the center of galaxies. But there weren't, well, there were sort of, what do I wanna say here? There are some supermassive black holes that light up because matter's falling onto them. So remember, black holes themselves can't emit light. So how do you detect them? Do you see it go away? The light disappears? Well, you see it get this material that's right, that's very energetic right outside where light can escape. So there's this endemic phenomena that led people to think about these supermassive black holes and these galaxies are called active galactic nuclei because their nuclei or centers are very active. And people started to talk about them and there was a wide variety of ideas about how they might form in the sense that there was a debate about whether or not, if you're gonna talk about supermassive black holes, did they form before the galaxy and seed the galaxy or did the galaxy form first and then seed and drive the formation of the black hole? And that was interesting. It's kind of like a chicken or the egg question, but today we understand that that's actually not even the right framework. So most... It's the wrong question. It's the wrong question. Today we see that the mass of these supermassive black holes seem incredibly well correlated with the mass of the central part of the galaxy over large range of masses. So from a million to a billion and over a large range of time scales. So the earliest galaxies in the universe to galaxies that are much closer to us. So we're looking at the more recent history of the universe. And that suggests that there has to be whatever formed one form the other, there's a synergy and there has to be some feedback mechanism to keep that in lockstep. So to come back to your question about was there a theory? There was a theory that they might exist but there wasn't clarity about how you would get them to form. Okay, okay. Now, when you set out to do this you set out a very long time ago to start figuring it out. And I believe you were told it can't be done. Yes. Lovely word, no. Now, does that fire you up when you're told it's impossible? Of course. I've been told no a lot in my life and I've been up learning to ignore it. So like can't escape a black hole, supermassive or not? And I'm pretty sure electromagnetic energy of any kind can't escape either, correct? Correct. Okay, so nothing escapes. So now here's the wide open question. How are you able to observe the existence of this theorized or supermassive black hole? So actually the way we've kind of gotten to this question is nice because one thing that's different about our galaxy is it's not one of these active galactic nuclei. So there's no evidence from activity in the middle that pointed the way. But so in asking this, in looking, we're looking to make sure that we understand do these supermassive black holes exist? And in all kinds of galaxies because there's nothing particularly special about ours. And the way we've done this is to look at the gravitational influence from the black hole on the things around it and in particular the stars. So gravity is gonna force these stars to orbit whatever mass is inside its orbit. So very much like the planets orbiting the sun, you can weigh the mass of the sun by measuring the motion or measuring the orbit in particular of these planets. So you do the same thing. Basically that's what we're after. And in the beginning, we did it how many people think about these experiments which is just to look at the speeds of stars. So you look for fast moving things really close and slower things moving further out. Smart, actually let me say that more grammatically correctly. You look for things moving faster closer to the center of the galaxy and then you look for the evidence of the fall off of speed as you get further and further away in a very specific way. But we're inside the Milky Way. Makes it a little tricky because we're looking at the Milky Way edge on, right? So you got to look through everything in the Milky Way towards the center of the galaxy. Right, so it's a little tricky. It's a little tricky. So it's in our backyard, but our backyard is messy. So we're in this galaxy, the Milky Way. So it's a flattened disk-like structure. The sun and our solar system is about halfway out from the center. And so we're trying to look towards the center of the galaxy. And so in that plane, so not only are there a lot of stars in the plane but there's a lot of dust. I like to say I'm in Los Angeles. I get the effect of dust. It's like smog. It's really good at blocking optical light. Because optical light has a wavelength that's roughly the size of the dust particles. So it just reflects off right off of it in optics. It absorbs. I mean, those are the two mechanisms. And both things are actually happening. And what our trick is, is to go to the infrared. So to look at light that has a longer wavelength. So it's larger roughly than the size of the dust particles and therefore can penetrate through all this dust that's in the plane of the galaxy. So having technology that allows us to perceive infrared radiation or light is super important. And that's a technology that's really undergone and huge advancements over the last 30 or 40 years. In terms of instrumentation that we have today? Yeah. And to think night vision goggles. Those are actually taking pictures in the infrared. You glow at infrared wavelengths. One of my favorite things in one of your lectures was when you talked about being in the area of where all the aerospace engineers are and having been an engineer in the aerospace industry who worked on a helicopter night vision system. I'm like, yeah, that's it. That's right. You're welcome. I wanted to be at UCLA because UCLA really understood. Well, actually, let me back up for a sec. Part of the technology of how we did this is we're doing this with really big telescopes. And when I started my faculty job, the reason I wanted to be at UCLA was twofold, really. One is it gave me access to the largest telescope in the world, which is really what I wanted more than anything else. But it's co-owned by the University of California in Caltech. And what UCLA did, which is a campus of the University of California, they looked to invest in an area that was emerging right at the beginning of this, when this telescope was opening up. This is Keck Observatory, it's out in Hawaii. And UCLA recognized that they're in the middle of Los Angeles, like the aerospace industry. So there's lots of investment in infrared technology here. So they hired a bunch of faculty interested in the science and technology associated with infrared work. So I'm part of that effort. I was the third hire. And I feel super lucky because that strategy means you have colleagues that you wanna talk to. And it's both the people part and the technology part that has really enabled this project to be so successful. So let's talk about the Keck telescope itself. You said it's the largest telescope in the world. And you're including anything we put in space has to be smaller on account of you gotta lift it and everything, right? That's one of the stumbling blocks so far until we fix that gravity issue. So how big is the Keck telescope? So we talk about the size of telescopes by describing the diameter of the primary mirror, which is the element that collects all the light. So the diameter of the mirror for the Keck telescope is 10 meters, which is like the width of a tennis court just to give you a sense of scale. Okay, so like this sensor on a digital camera, the bigger it is, the more light it can collect. Yeah, it's like a rain bucket is the way I like to think about it. It's like a big opening. So the bigger the opening, the more light you're gonna collect or rain that you're gonna collect. So, yeah. And in this case, we're talking about infrared energy, but- Right, but that's actually not why, for my work, the Keck is so valuable. So there's two reasons that big telescopes help the business of studying the universe. I mean, first is this idea of being a light bucket. So it makes you very sensitive to faint things, but the second aspect is it helps your ability to see fine detail. So the larger your telescope, the finer the detail that you can see. So the analogy I like to give is, if you think about that technique, the painting technique of pointillism, where you paint rocks, and if you walk closer to the painting, you see the individual dots. So having a big telescope is like walking closer to the painting. Okay, okay. So you've got this giant telescope, we're doing infrared so we can see through the dust, but there's still problems since the telescope is on Earth. Oh yeah. We've got to see through the atmosphere. And we're out in Hawaii, so we're up high on a volcano and maybe not a lot of smog in Hawaii. Also plus. Still got atmosphere to deal with. Oh yeah. So the atmosphere makes that second attribute of seeing fine detail not so easy to achieve. It's the atmosphere distorts our images. So rather than being nice and crisp, they're blurry. And there are two ways of thinking about this. The atmosphere is like a river that's moving over across the telescope. And that's like a river of water when you're trying to see a pebble at the bottom. So a lot of my work is focused on how do you undo the blurring effects of the Earth's atmosphere so you can get back to that promised resolution of these really big telescopes? You know, one of my, as a mechanical engineer who worked on with voice coil actuators to move mirrors and I worked for Hughes Aircraft Company and I'm pretty sure this is a correct statement. I think we invented the laser. Wow. Your next part of explaining how you compensate for this waviness of the atmosphere with lasers, just warmed my little mechanical engineer's heart. I can see why it's so much fun to talk to you, Allison. We resonate on so many levels. Yeah, so the technology like the infrared detectors has evolved a lot in terms of how can you do this correction business? And so when I started, we used a very simple technique which was much more software intensive. So you took lots of short exposures and then you, through data analysis and clever code, you could figure out what the atmosphere was doing versus what the underlying object is. But today- This is kind of an estimate, right? It's no, it's a- It's called, it's a, the process is called deconvolution and we, so what would be the analogy or good analogy? You take thousands of frames. So one, this is not totally accurate. So this is a total cheat, but I'm gonna use it anyway. You know the object, underlying object is constant, but the atmosphere is always changing. So by taking thousands, you can figure out what the atmosphere- I mean, all these things are estimates. Actually, that's fair. Actually, Allison, you're totally right. Let me just back up and say, yes, it's an estimate. You try to model what the atmosphere is doing versus, and take it out. But today, there's all this advancement with hardware. So mechanical engineers and then the laser people, as you put, are really key here. So the technique is called adaptive optics. So it's a way of putting a mirror that's segmented in the path of the light coming in from hitting your primary mirror between that and your detector. You put this mirror, you reflect it off a mirror that's called a deformable mirror because it's doing exactly that. It deforms in a way that's trying to counteract the effects of the atmosphere. And the mental picture I like to have here is if you think about a circus funhouse mirror that makes you look all warpy, that you're trying to put a second mirror that has the opposite shape of the mirror. Or the conjugate shape so that you look flat again. But that first warp is changing a thousand times a second. So you gotta keep up and figure, well, first of all, figure out what the atmosphere is doing and then continually update it. So as you mentioned, this laser business was the trick because you gotta look at something bright. And it turns out there's not that many things that are bright enough in the sky to do this trick. So you look at something you understand through the atmosphere. And then you use that to say, ah, I know how to make that deformable mirror move. I think it's like 1% of the sky has a natural star that's bright enough to do this game. So you, I mean, this is an incredible fluke of nature that up at 90 kilometers, there's a very thin layer of sodium atoms from all the meteorites. So when people like go out camping and see the shooting stars and we say, make a wish, I'm thinking, thank goodness, that's re-supplying my layer. The sodium layer? My sodium layer. So you shine a sodium laser that's tuned to a transition of these little atoms and you make those atoms shine like an artificial, well, it is an artificial star that you can then look at and correct. So basically- And it's a star right where you want it to be. Right where you want it to be. To point towards the 1%, which isn't maybe where you need to look. Like 1%, that's just too little. I want to look at the center of the galaxy and there's no, and it doesn't work there very well. So that, that was transformative when that technology became scientifically mature is I guess how I would put it. And that happened in roughly 2005 at the center of the, at Keck Observatory. That was the first big telescope that for which this really worked well. That is, I love everything about that. That is absolutely terrific. The steering mirror that I worked on was on this helicopter night vision system and it was called the image motion compensation mirror. So it's four little voice coil actuators like what's pushing on your mirror. But I was simply rotating a mirror to take out the vibration of the helicopter. Wow, that's so cool. I'm destined to have this conversation. It's so similar. Yeah, yeah. So, okay. Now let's talk about what you've found. You look at the center of the galaxy you've now got these clear, you can see clearly. I can see clearly now. And now what did you see? We saw stars. And in terms of like not getting the initial telescope time there were three critiques. One is that the technique wouldn't work. So it did. And then the second is you wouldn't see stars and you wouldn't see the move. So three. So it just was so exciting when we first went to the telescope and got our first images. It was clear that things worked and there were so many stars. And then by year two, because you basically would go back once a year in the beginning years. And these stars were hauling. I mean, these stars are having, a small fraction of the speed of light. And anytime you can talk in those units you're moving pretty fast. And that's important because you can watch them for a long enough time to see are they going around something? Well, in the beginning we only proposed to do a three. So three year project. This is the project that was turned down to begin with because we were only looking for speeds. So you don't know how long the orbits would be because that depends on whether or not there is a black hole and how massive it is. So the beginning thing is let's just see if you can see fast moving stars in some part of the area and then a fall off of those speeds away from that location. So wherever the black hole is, it's gonna peak. So you don't know exactly where the black hole is. I mean, we had some theories. And what's so exciting is it was so clear. I mean, it could not have been clear that things were moving incredibly fast and the speeds fell off with the exact relationship. So it's very simple relationship that goes one over the square root of the distance. So in other words, it's further slower. And at that point, you can estimate how massive the black hole is already from that from in a statistical way. So you had to make assumptions about the kinds of orbits that these stars are on. And the great thing about science, I mean, I love this, I mean, you have to love this aspect of science. It's negatively constructed in the sense that people, our job is to be cynical. So what else could it be? And so the minute we put out this paper, people started pushing back and saying, well, it could be this or it could be that or this other force could make these things move fast. And of course, what do you do as an observer or an experimentalist? You say, we gotta do more. We gotta go the next thing. And freshman physics or first year college physics will tell you the next thing that's gonna happen is these things are gonna go from moving on straight lines because you're just moving measuring a small segment of the orbit to accelerating. So velocity turns into acceleration. So you say, let's see those accelerations. And sure enough, that was our first three years. We got the velocities, two more years, we get accelerations. And because you were able to observe them longer, you could see. We basically just asked for more telescope time. So we've gone from new kid on the block, trying to get on the telescope to being a little pig ear. And at that point, the evidence, oh, I should say already with the velocities, the evidence for the existence of supermassive black holes, if you believe that that's what we were seeing had gone up by a factor of 1,000 compared to any other evidence for a black hole anywhere, supermassive black hole anywhere in the universe. So that was the late 90s. And then the accelerations told us that the orbits could be as short as 10 years. Now you're talking human lifetime for orbits because you don't know. And just like, I mean, there's a reason why people wouldn't have accepted the idea of orbits to begin with. Our sun takes 200 million years to go all the way around. Like you're not gonna watch that. We don't live long enough. You're never gonna get past that straight line segment. Exactly, we're on straight lines here. So it was super exciting to realize that this was a reasonable experiment to propose. And so we kept going and indeed made that next leap of actually making those measurements and measuring the stars. And now we have thousands of them, but it's the closest ones, those speedsters that are really gonna drive your knowledge. Me, you need everything, it turns out. They all play together. Everybody has to act like a team to get everything registered, but the power of the experiment comes from the really fast moving stars that are on the shortest orbit. So those things go hand in hand. And my favorite star, as you know, SO2. Those are the t-shirt that says SO2 on it. I need a t-shirt. I don't have a t-shirt. I'd like that, like no other explanation, but if somebody knows, they know. SO2, are you in the know? Of course, it's also sulfur dioxide and a massive free-buff group. And then you'll get all those nerds. So what is special about SO2 then? Well, it goes around every 16 years and it tells you that there's four million times the mass of the sun inside a region that's the size of our solar system. And that... Wait, let's say that again. Four million times the mass of our sun inside something the size of our solar system? Yeah, and that's amazing. If you think about like our own solar system where the mass of that is one. And so in this region of the space, it's a million times higher or four million times higher. And in fact, if you think about density, that's really enhanced the inferred... Well, I'm gonna call dark matter density. Okay. Up by a factor of 10 million. And that's why we say the evidence for a supermassive black hole goes up by a factor of 10 million. So the first factor of 1,000 came when we got the velocities and the next factor of 10,000 comes from orbits. And the thing I do like to say, like just to... I mean, that's a huge number. Like think about anything in your life that you'd like more of. I mean, I don't know, free time, salary. And if you could multiply it by a factor of 10,000, you would notice. Yeah, so, and that's in... Okay, 10 million. Not 10. 10 million. 10 to the seven, 10 million, yeah. And that change was in what length of time that you found that? Well, 1995 was the beginning of the experiment. And you could sort of say step one, the velocities took the first three years. And then the next step got announced in the early 2000s. And then of course it just keeps getting better and better. So it kept going. This time next year. Well, the way I like to think about it today is that every time you go through what I call a turning point, which is like the closest approach and the furthest approach or half of the orbit, you get a chance to go deeper into the physics. So now we're going to the business of testing how gravity works near a supermassive black hole. And kind of while, like if it really is a black hole, you should be able to see those kinds of effect. And in 2018, those became, the first ones of those things became visible and now we're kind of on the next stretch. And again, things are emerging and emerging in a way we could not have anticipated. Yeah, so it's- I think one of the things that you talked about that just really struck me was how delighted you were when you found out what we were wrong about. About the age of the stars at the center of the galaxy, right? Or at the center of the orbit, orbiting around the supermassive black hole. That to find out you're wrong is like, ooh, yay, new puzzles. Yeah, it's like being a kid in a candy shop. There's so much more to do. And I guess it's one of the things I love about technology advancements is that it gives you a new opportunity to see, well, to derive new information that you didn't have before. So in this case, as we were talking about at the beginning of our conversation, we were in that early technique where it was sort of make your computer do all the work. You could only take images, which means you didn't know what kind of stars you were looking at. They were just bright spots. So the other thing about the more advanced technology of adaptive optics, which allows you to integrate for more than a 10th of a second, you can get, take spectra. So you can break up, look at the components of the light, which is what allows you to figure out, well, what kinds of stars are we looking at? What's the temperature of these stars? And that's what allows us to figure out from, I mean, it is from models to compare to models, how old they are. And that, and I mean, it was just so striking how much those early observations and upset the apple cart. I mean, things just did not make any sense. And it never dawned on to me, to never dawned on me that this, this idea that I like mysteries, that scientists in general like mysteries is a surprise. I was talking to some reporter who just said, you seem most happy when you're confused. Because otherwise I have nothing to do. It is, it is absolutely true. I mean, it is fun to solve the mystery, but it's also the process of figuring it out. And the, you know, in some sense, the hardest part of the work is figuring out what is an interesting question. What do you, so having observations that say things aren't working points you to your next step, to your next endeavor. And figure out what that question should be so that you can figure out what experiments to do next when observations make. Exactly, how do you advance the frontier of knowledge? I mean, you can be very deliberate, like I need something and therefore I'm gonna try to develop it, but so much of basic research, you're just trying to understand how things work. And, you know, many times people say, well, why should we care? I mean, I get that question all the time, but there's lots of examples. Like if you look at your cell phone, almost all the technologies in there started as basic research where people were saying, why should we care? Like, this is a- Right, satellites, GPS. Yeah, just for a few, like electricity, yeah. You know, some of those things. Steve asked me to ask you a question that might require a lot more background than we have time to cover, but he did want to know whether any of your observations have advanced our understanding of dark matter. Now, you bleakly referred to dark matter density, but I'm not sure I could even start to explain what dark matter is. Oh, well, it's one of those things like black holes. The definition is really simple. What it is is not. The definition of dark matter is it's matter that, and matter just means it has a, you know, it interacts gravitationally. Mass is okay. And dark means it emits low light. So dark matter simply means you have matter and it's not going to emit any light. So black hole is an example. In other words, we can't find it. Well, you can if you were just a grab, you know, if you just looked at the gravitational attraction, but you're not going to see it by taking a picture. Okay. With a camera, like an infrared camera, an optical camera, you name, you pick your favorite kind of light x-rays, gamma rays, you're not going to see it. So worse, the stuff that's emerging right now that I just alluded to, if we're right, and of course we could be totally, we could be making a mistake. I mean, that's always the interesting thing about discovery, when things don't work or something's emerging that you didn't expect, it's either a discovery or a mistake. And you have to work really hard to convince yourself. Which one? Which one? And that's, you know, that's part of the discipline of science. And in our case, I'm still nervous, but I'm kind of excited as well, because we can't make this result go away. So the shape of the orbit, over time, the orientation of these orbits should shift. It affects both of how gravity works near a black hole, like how Einstein predicts it as opposed to Newton, as well as if there's extended dark matter. Like, and you expect that actually, there are theories that say the black hole should be surrounded by little, smaller things that also don't emit light. And there's two possibilities, but the orbit going the other direction would be a detection or discovery of dark matter around the black hole. So we're excited about it. We may be sensing it. And that's what we're working super, super, super hard on. So you're saying right now, really observations that are emerging is that the orbits are orienting themselves in the opposite direction of what you would expect if there was no dark matter. Yeah, around the black hole, yeah. Around the black hole. Yeah, yeah. Okay, so you've got little hairs tickling on the back of your neck thinking about it, right? Oh yeah, absolutely. And in terms of where this conversation is gone, closest approach happened last in 2018. And so you expect the signal to start emerging post-2018 and to become strongest or your sensitivity to it is gonna be sort of optimized in 2026. Cause that's eight, yeah, eight years, I can do math and talk to the same. So that's where we are today, in 2023 is that climbing out to see, and we're kind of right where we expect to be in terms of the sort of the next stage of the evolution of this kind of work. Oh, that is so exciting. This is really, really cool, I love this. I'm gonna switch gears on us a little bit. Even though you're a Nobel laureate for Crane Out Loud, you could do whatever you wanted. You still teach undergraduate astronomy, is that correct? That's right. Why do you do that? Well, for a couple of reasons. One, well, when I started teaching at UCLA, I was really, with very few women around in my field, and I really felt strongly that one of the most effective things that one can do as a woman doing science is to be a role model. Cause I think role models are so important. And I'm not an expert in this, or topic. So the most effective thing I could do is just teach at the undergrad level, at the introductory under. To be seen. To be seen, to be just somebody who doesn't look like what we think of as a scientist. And I think that's healthy both for the young men and the young women, and anybody who's not part of the mainstream demographics where you are. So that's sort of how I got into teaching at the introductory level. And I also discovered I love it. I mean, it's really fun to teach the undergrads. Today, my favorite class to teach is the Introductory Astronomy and Astrophysics for majors because you're kind of hitting them early on and you have the opportunity to encourage them into the research world, to not only teach them the disciplinary stuff, like how, you know, the tools, the homework, but also to encourage them to get this opportunity that they have at a research university. So that's, you know, it's part of the wonderful thing about doing research in a university setting. You know, our job is to create new knowledge by our research, but it's also to create new knowledge through creating new scientists. So you work in the farm team is what you're saying. Yes, I guess I am. You know, I always try to recruit some of the students from the class into the team and that, you know, that's it. Wait, wait, you didn't do this all single-handedly? Oh yeah, no, absolutely not. There's been a big group working with me and you know, there's a huge team. Right now, you know, we started with a team of three. Now we're about two dozen core members and because they're students, they keep graduating. So since this project, we've had roughly 70 people who have been involved in a meaningful way over the 29 years that we've been going at this. How exciting for all of them. Now, there's so many stories about actually getting the Nobel Prize, but one of my favorites was your description of you got a call from another woman when you won, another woman who had won the Nobel Prize in physics. Yes, I did. That was one of my favorite communications with somebody that day. So this is Donna who won it in 2018. And she said, welcome to the club. There's now, it's a club of two, which is the number of women who won the physics Nobel Prize who are alive. That is just so sad. Yeah, it is sad, but it's also... But it doubled. It doubled, I mean, in terms of the number of women who have received the Nobel Prize in physics, we're now at 2%, but I have to say, boy, the standards were high with Marie Curie winning the first one. I mean, she won two and her daughter also won one. I mean, she is a rock star. Oh, well, I would consider you're a rock star as well. I think one of my favorite things is that you are so young that you have so much runway coming to delight us with science. And that really excites me. No one else is looking at you right now, but I know that you're young and it's just really fun to know that there's all these puzzles out there that are gonna get you excited and things you're gonna solve for us. I think it's just amazing. Thanks, Allison. I'm super excited about the future and I look forward to what's in store. Now, I've put a link in the show notes to the UCLA Galactic Center Group. That's where people should go if they wanna go learn more about the science, more about the technology. There's even a really cool animation of SO2 going around and you can download it for your own so it can be your desktop screensaver if you want. All right. Lots of other pictures, yes. Yeah, very, very cool. Andrea, thank you so much for spending your time with us. Like I said, I've been looking forward to this for a long time and it was even more fun than I'd hoped. No, well, for me too. Thanks, Allison. It's a pleasure talking to you.