Anna Frebel: Origin and Evolution of the Universe, Galaxies, and Stars | Lex Fridman Podcast #378

1. 0:00 – 1:02

   Introduction

   1. AFAnna Frebel0:00

      ... I would run outside and just lay on the ground under the southern Milky Way, beautiful right up there, and I would just l- lay there like the snow angel and just kind of let my thoughts sort of pass through my brain. And this is when I personally have a feeling that I'm a part of it, I, I belong here, rather than feeling kind of small. Yes, I'm small, but there are many other small things, and lots of small things make one big whole.

   2. LFLex Fridman0:27

      (air whooshing) The following is a conversation with Anna Frebel, an astrophysicist at MIT studying the oldest stars in the Milky Way galaxy in order to understand the chemical and physical conditions of the early universe and how from that our galaxy formed and evolved to what it is today, the place we humans call home. This is the Lex Fridman Podcast. To support it, please check out our sponsors in the description. And now, dear friends, here's Anna Frebel.

2. 1:02 – 8:11

   First elements

   1. LFLex Fridman1:02

      Let's go back to the early days. What did the formation of the Milky Way galaxy look like? Or maybe we want to start even before then. What did the formation of the universe look like?

   2. AFAnna Frebel1:13

      Well, we scientists believe there was the big bang, some big beginning. (laughs) But what is important for my work, and I think that's what we're going to talk about, is what kind of elements were present at that time.

   3. LFLex Fridman1:26

      Mm-hmm.

   4. AFAnna Frebel1:27

      So the big bang left a universe behind that was made of just hydrogen and helium and tiny little sprinkles of lithium. And that was pretty much it. And as it turns out, it's actually quite hard to make stars or any structure from that. That's fairly hot gas. And, uh, so the very first stars that formed prior to, to any galaxies were very massive stars, big stars, hundred times the mass of the sun, and they were made from just hydrogen and helium. So big stars explode pretty fast, after a few million years only. That's very short on cosmic timescales. And in their explosions, they provided the first heavier elements to the universe, because in their cores all stars fuse lighter elements like hydrogen and helium into heavier ones, and then that goes all the way up to iron, and then all that material gets ejected in these massive supernova explosions. And that marked a really, really important, um, transition in the universe, because after that first explosion, it was no longer chemically pristine.

   5. LFLex Fridman2:41

      Mm-hmm.

   6. AFAnna Frebel2:41

      And that set the stage for everything else to happen, including us here talking today. (laughs)

   7. LFLex Fridman2:47

      So what do you mean by pristine? So there's a, a whole, uh, complex soup of elements now as opposed to just hydrogen, helium, and a little bit of lithium?

   8. AFAnna Frebel2:57

      Yeah. So after the big bang, just hydrogen and helium. We don't really need to talk too much about lithium because the amount was so small.

   9. LFLex Fridman3:04

      Mm-hmm.

   10. AFAnna Frebel3:05

       Um, and after these very first stars formed and exploded, they, th- the, he- heavier elements like carbon, oxygen, magnesium, iron, all of that stuff was, was suddenly present in the gas clouds, uh, ti- in tiny amounts only, very tiny amounts, but, um, that actually helped, especially the carbon and the oxygen, to, to make the gas cool. These atoms are more complicated than hydrogen, that's just a proton, and so it has cooling properties, can send out photons outside of the gas cloud, so the gas can cool. And when you have gas that, that gets colder and colder, you can make smaller and smaller stars. So you can cl- fragment it and clump it and turn it into stars like, like the sun. And the cool thing about that is that when you have small stars like the sun, they have a really long lifetime.

   11. LFLex Fridman3:57

       Mm-hmm.

   12. AFAnna Frebel3:57

       So those first low-mass stars that formed back then are still observable today. That is actually what I do, I try to find these early survivors, because they tell us what the gas looked like back then. They have preserved that composition of these early gas cloud, the p- the chemical compositions, um, until today. So I don't need to look very far, uh, into the universe (laughs) to study all the beginnings. I can just chemically analyze the oldest stars, and it's like unpacking everything that, that happened back then. It's very exciting.

   13. LFLex Fridman4:34

       So to just reiterate, so in the very early days, in the first few million years, there was giant stars that's mostly hydrogen and helium, and then they exploded in these supernova explosions, and then they m- made these clumps of-

   14. AFAnna Frebel4:48

       Yeah. So, uh, the first stars-

   15. LFLex Fridman4:50

       Not pristine. (laughs)

   16. AFAnna Frebel4:51

       (laughs)

   17. LFLex Fridman4:52

       Not pristine clumps.

   18. AFAnna Frebel4:53

       Yeah. Pretty much.

   19. LFLex Fridman4:54

       Fun.

   20. AFAnna Frebel4:54

       So it took a few hundred million years for the first stars to emerge.

   21. LFLex Fridman4:57

       Yes.

   22. AFAnna Frebel4:58

       And then they exploded after a few million years, kaboom.

   23. LFLex Fridman5:01

       Kaboom.

   24. AFAnna Frebel5:01

       And then it's like, I always consider the universe like a, you know, a nice soup.

   25. LFLex Fridman5:07

       Mm-hmm.

   26. AFAnna Frebel5:08

       And then these first supernova explosions kind of provided the salt, you know, just a little sprinkle of heavier elements.

   27. LFLex Fridman5:15

       Yeah.

   28. AFAnna Frebel5:15

       And that made it really tasty. (laughs)

   29. LFLex Fridman5:17

       Mm-hmm.

   30. AFAnna Frebel5:17

       Just changed it completely, right? And that changed the physics of the gas, so that meant that these, these gas clouds that were, you know, surrounding the, the, the former first stars, they could now cool down and clump and form the next generation of stars that now included also little stars. And, um, as I just mentioned, the small stars have these really long lifetimes.
3. 8:11 – 11:47

   Milky Way

   1. LFLex Fridman8:11

      uh, maybe just a step back. Like, what is a galaxy? What is a proto-galaxy?

   2. AFAnna Frebel8:15

      I love that question. So the galaxy is, um, a huge assembly of stars. The Milky Way contains something like 200 to 400 billion stars. And most of the material and the stars are in the disc. And when we look at the night sky, uh, what we see as the Milky Way band on the sky, that is actually the in- more... The inner, the next inner spiral arm, because we actually live in a spiral disc galaxy, so the Milky Way is a spiral disc galaxy, um, and we're looking, um... Actually depends a little bit. In the northern hemisphere, we're looking out of the galaxy (laughs) , so we're seeing the next outer spiral arm.

   3. LFLex Fridman9:02

      Mm-hmm.

   4. AFAnna Frebel9:02

      And, as you can imagine, there's only dark space behind that-

   5. LFLex Fridman9:06

      Mm-hmm.

   6. AFAnna Frebel9:07

      ... so w- we don't see it all that nice in the sky. But if you travel to south, uh, to the southern hemisphere-

   7. LFLex Fridman9:12

      Mm-hmm.

   8. AFAnna Frebel9:13

      ... let's say South America, you see the Milky Way and it looks so different in the sky because that's the next inner spiral arm and that's backlit by the galactic center.

   9. LFLex Fridman9:22

      Mm-hmm.

   10. AFAnna Frebel9:23

       The galactic center is- is a very big puffy, you know, region of gas. There's a lot of star formation th- that... The- the galactic party is happening there, so it's very bright and it- it makes for this very beautiful Milky Way on the night sky that we see. So actually, if you- if you ever get the chance to experience that, I encourage you to almost, like, close your eyes while seeing this and imagining that you're sitting in this kind of disc, in this pancake, and you're just kind of looking right into it and you can- you can really feel that we're in this 2D disc and then you can imagine that there's a top and a bottom and that- that we're really part of the galaxy. You can really experience that. W- We're just not- not just lost in space somewhere, but we- we're really a part of it, and, you know, knowing a little bit about the structure of the Milky Way really helps.

   11. LFLex Fridman10:14

       Do you feel small when you think about that? When you look on that spiral on the inside of the Milky Way and then you look out to the outside? Like, how are we supposed to feel?

   12. AFAnna Frebel10:25

       I- I don't know. I- I- I don't feel small, necessarily. I feel in awe and I feel I'm a part of it because I can really feel that I'm a part of it. Um, I think for many people, they think like, "Oh, there's just the planet and then there's nothing."

   13. LFLex Fridman10:41

       Mm-hmm.

   14. AFAnna Frebel10:42

       And that's almost a little bit sad, but it- it... That's really not the case, right? Because there's- there's so much more and I really like to imagine, wow, I'm- I'm sitting in this big galactic merry-go-round and we're going around the center and I can see the center-

   15. LFLex Fridman10:57

       Mm-hmm.

   16. AFAnna Frebel10:57

       ... above me, right? And I can almost feel like we're going- going there (laughs) . Um, of course, we can't really feel that, um, but the sun does circle the galactic center.

   17. LFLex Fridman11:09

       But there's a kind of sadness too, like looking pictures of a nice vacation place. All we get is that light, an old light. Is- Do you feel, like, sad that we don't get to travel or you and I will not get to travel there and maybe humans will never get to travel there?

   18. AFAnna Frebel11:27

       Yeah, I always wanted to travel into space and see the Earth and other things from- from up there. There- there's- there's certainly that. But I don't know. It's- it's also okay to just be at our vantage point and- and see it from- from here.

   19. LFLex Fridman11:43

       With the sensors, with the telescopes that we have and explore the possibility.

4. 11:47 – 14:52

   Alien worlds

   1. LFLex Fridman11:47

   2. AFAnna Frebel11:47

      Yeah.

   3. LFLex Fridman11:47

      I mean, there is a kind of wonder to the mystery of it all, what- what's out there, what interesting things that we can't possibly imagine. You know, there could be all kinds of life forms, bacteria, all this kind of stuff. I tend to believe that, um... You know, it depends on the day. I tend to believe there's just a lot of very primitive organisms just spread out throughout and they built earth, little things, like bacteria type organisms. Um-... and just to think what kind of worlds there are, 'cause they're probably really creative living organisms, 'cause the conditions... I guess the question I'm wondering to myself when I look out there to the stars, w- how different are the conditions on the different planets that orbit those stars?

   4. AFAnna Frebel12:28

      It will definitely be very different. I mean, the variety out there is, is huge. We know now that, I think, it's about every other star has at least one planet. I already mentioned the number of stars in the galaxy. I mean, you know (laughs) that- that's, it's a huge number of planets out there. So who knows what that looks like? All we know is that there is, there is a lot of variety. We don't quite yet understand what drives that, what governs that, why that is the case, why is it not all one size fits all. Um-

   5. LFLex Fridman13:05

      You mean the dynamics of, uh, planet formation, like exoplanet formation, or star formation, the whole shebang?

   6. AFAnna Frebel13:11

      All of it. All of it. Um, star formation is, remains a much researched topic. We kind of, we definitely know that it works. (laughs)

   7. LFLex Fridman13:19

      I am sure.

   8. AFAnna Frebel13:19

      Because all the stars are there. (laughs) Same for the planets. But the details are so varied per gas cloud, right? Um, it's very hard to, to come up with very detailed prescriptions. Broadly, we have figured it out. You need a gas cloud. You need to cool it. Something clumps and fragments, and somehow it makes a star with planets or without.

   9. LFLex Fridman13:44

      But the dynamics of the clumping process is not fully understood?

   10. AFAnna Frebel13:47

       No, no. And, and it- it... The local conditions are so varied, right?

   11. LFLex Fridman13:52

       Yeah.

   12. AFAnna Frebel13:52

       I mean, it's, the same with, you know... All people look like people, but individually we look very different.

   13. LFLex Fridman13:57

       So even the subtle diversity of the formation process creates all kinds of fun-

   14. AFAnna Frebel14:02

       Yes.

   15. LFLex Fridman14:02

       ... differences.

   16. AFAnna Frebel14:02

       So you, you... We just don't know how this turned out in an individual case, and it's kinda hard to, to figure it all out and, and to take a look, certainly with planets, right? The chance forever, to ever actually take a picture of a planet is, is minuscule because they don't shine. (laughs) So they're really dark.

   17. LFLex Fridman14:23

       Yeah.

   18. AFAnna Frebel14:24

       So I'd say there's, there's, there's a lot of possibility out there, but we have to be a little bit more patient (laughs) before we-

   19. LFLex Fridman14:31

       Yeah, or come up with technologies where patience becomes less necessary-

   20. AFAnna Frebel14:36

       Yes.

   21. LFLex Fridman14:36

       ... by extending our lifetimes or, or increasing the speed of space travel, all that kind of stuff. Humans are pretty, pretty intelligent. They're pretty, uh-

   22. AFAnna Frebel14:45

       Sometimes, yeah. (laughs)

   23. LFLex Fridman14:47

       For the most part, I hope, on the opt- when I'm... on the optimistic days.

5. 14:52 – 20:05

   Protogalaxies

   1. LFLex Fridman14:52

      Well, maybe just to linger on the, on the what a galaxy is. Um, what should we know about our understanding of black holes in the formation? Is that an important thing to understand in the formation of a galaxy? Like, uh, so all the orbiting, all the spiraling that's going on, how important is that to understand?

   2. AFAnna Frebel15:11

      All, all of the above. (laughs) That's what makes astronomy really hard but also really interesting, right? No day is like another because we always find something new. Um, I want to come back to the, the idea of the proto-galaxy-

   3. LFLex Fridman15:23

      Yes, yes, yes.

   4. AFAnna Frebel15:23

      ... because that actually ma- matches or, you know, relates to, to the black hole formation. So most large gal-... well, pretty much all large galaxies have a super massive black hole in the center, and we don't actually know, don't... We don't really know where they come from. (laughs) Again, we know that they are there, (laughs) but how, how do we get there? So if we go back to the, to the early universe, right, we had a, a little galaxy that just sort of, you know, I don't know, had some small number of stars. It was the first gravitationally bound structure that, that was held together by dark matter because dark matter actually kind of structured up, you know, first before the luminous matter could because that's what dark matter kind of does. And it, it, it started to hold, um, gas and then stars sort of together in these first very shallow, um, what we call potential wells, so these gravitationally bound systems. And then the Milky Way grew from absorbing neighboring smaller, even smaller systems. And somewhere in that process, there must have been a seed for one of these super massive black holes. And I'm, I'm not actually sure that it's clear right now kind of what was there first, (laughs) the super massive black hole, uh, or the galaxy. So lots of people are trying to study that. And of course the, the black hole wasn't as massive back then as it is these days, um, but it's... that's a, uh, it's a big area of, of research. And the new, um, James Webb, the JWST, the telescope, the infrared telescope in space, is, um, is working on... many people are working on that to, to figure out exactly what, what happened, and there are some sur- surprising results, um, that we really don't understand right now. So...

   5. LFLex Fridman17:15

      So to solve the, uh, the chicken or the egg problem of, uh, do you need a super massive black hole to form a galaxy or does the galaxy naturally create the super massive black hole?

   6. AFAnna Frebel17:24

      Yeah, yeah. I mean, I think to some degree we, we can answer that because there are lots of little dwarf galaxies out there. You know, the Milky Way remains surrounded by many, um, dozens of, of small dwarf galaxies. I have studied a, a bunch of them. And to the extent that we can tell, they do not contain black holes. So there certainly were gravitationally bound structures, so either you can call them proto-galaxies or dwarf galaxies or first galaxies. They were definitely there, but there must have been bigger th- things, like the proto-Milky Way, where something was different, right? What made them more massive so that, you know, they would gravitationally attract these smaller systems to, to integrate them. So we'll have to see.

   7. LFLex Fridman18:10

      How, how do we look into that, uh, the- into the, the dynamics of the formation and the evolution of the proto-galaxies? Is it possible? Do they shine? I mean, what, what are the...... set of data that we can possibly look at. So we got gravitational waves, which is really insane that we can even detect those.

   8. AFAnna Frebel18:30

      Yeah.

   9. LFLex Fridman18:30

      Um, there's light. What, what else can we, uh-

   10. AFAnna Frebel18:34

       So, that, that would fall into the category of observational cosmology.

   11. LFLex Fridman18:38

       Yes.

   12. AFAnna Frebel18:38

       And the, the JWST is, is the prime telescope right now to... And it promises big, big steps forward. This is in its early days, because it's only been online, like, a year or so. Um, but that collects the infrared light from the farthest, like, literally proto-galaxies, earliest galaxies. That light has traveled some 13 billion years to us, and they're observing these faint little blobs (laughs) . Um, and folks are trying to, you know, again, study the early, the onset of these early super massive black holes, how they shape galaxies. So they're, they're seeing that they are... They were there, you know, surrounded by already bigger galaxies. Ideally, I'd like for, for my colleagues to push a little bit further. Hopefully that will eventually happen (laughs) .

   13. LFLex Fridman19:31

       In terms of looking towards the older and older ones?

   14. AFAnna Frebel19:33

       Yeah. Yeah. And more, more and more sort of primitive in terms of the structure. But, of course, as you can imagine, if you make your system smaller and smaller, it becomes dimmer and dimmer, and it's further and further away. So we're reaching the end of the line from a technical perspective pretty quickly.

   15. LFLex Fridman19:49

       But it, it's... Dimmer and dimmer means older and older?

   16. AFAnna Frebel19:52

       Um, yes, in a sense, because it all started really small, right?

   17. LFLex Fridman19:58

       Yeah. Because it's smaller and smaller-

   18. AFAnna Frebel19:59

       Yeah.

   19. LFLex Fridman19:59

       ... which correlates to older and older.

   20. AFAnna Frebel20:00

       In, in, in that phase of the universe, it would. Otherwise, it, it doesn't, yeah.

6. 20:05 – 25:03

   Black holes

   1. AFAnna Frebel20:05

   2. LFLex Fridman20:05

      Uh, just to take a small tangent about black holes and... You know, because you do quite a bit of observational cosmology and maybe experimental, um, astrophysics. Um, what's the difference to you between theoretical physics and experimental? So, there's a lot of really interesting explorations about paradoxes around black holes and all this kind of stuff, about black holes destroying information. Do, uh, do those worlds intermix to you when you... Especially when you step away from your work and kind of think about the mystery of it all?

   3. AFAnna Frebel20:41

      Um, well, uh, at first glance, there, there isn't actually much crosstalk. Um, personally, I mostly observe stars, so I don't usually actually think too much of black hole, about black holes.

   4. LFLex Fridman20:53

      And stars is a fundamentally kind of chemical physical phenomena that doesn't-

   5. AFAnna Frebel20:57

      That's right. The physics is, is kind of different. It's not extreme.

   6. LFLex Fridman21:01

      Yeah.

   7. AFAnna Frebel21:01

      I mean, you know, you could consider nuclear fusion sort of be perhaps extreme. You need to tunnel... There, there's some interesting physics there (laughs) .

   8. LFLex Fridman21:10

      Yeah. Yeah. That's pretty .

   9. AFAnna Frebel21:11

      But it's, it's, it's just a different flavor. And I don't, I don't do these, um, kinds of calculations, uh, myself either. Um, I, I very much like to talk with my theory colleagues about these things though, because I find there's always an interesting intersection. And often it, it's, it's just... I've, I've written a, a number of, um, papers with, uh, colleagues who do, like, simulations about galaxies. And so they're, they're not quite as far removed as, let's say, the, the black hole, you know, pen-and-paper folks.

   10. LFLex Fridman21:41

       Mm-hmm.

   11. AFAnna Frebel21:42

       But, um, even in those cases, we had the same interest in the same topics, but it was almost like we're speaking two different languages.

   12. LFLex Fridman21:50

       Yeah.

   13. AFAnna Frebel21:50

       And we weren't even that far removed, you know?

   14. LFLex Fridman21:52

       Yes.

   15. AFAnna Frebel21:52

       Both astronomers and all. Um, and it was really interesting just to take the time and really try to, to talk to each other (laughs) . And it's, it's amazing how, how hard that is. You know, even amongst scientists, we already have trouble talking to each other. Imagine how hard it is (laughs) to talk to non-scientists and other people to try, you know, to... We're all interested in the same things as humans at the end of the day, right? But everyone has sort of a different angle about it and different questions and way of formulating things. And sometimes it really takes a while to, to converge and to, to get, you know, to the common ground. But if you take the time, it's so interesting to participate in that process. And it feels so good in the end to say like, "Yes, we tackled this together," right? We overcame our, our differences, not, not so much in opinion, but just in expressing ourselves about this and how we go about solving a problem. And these were some of my most, um, successful papers, and I certainly enjoyed them the most.

   16. LFLex Fridman22:56

       It can also lead to big discoveries. I mean, there's a... I think, uh, you put it really well in saying that we're all kind of studying the same kind of mysteries and problems. I mean, I see this in the space of artificial intelligence. You have a community, maybe it seems very far away, artificial intelligence and neuroscience. You know, you would think that they're studying very different things. But one is trying to engineer intelligence, and in so doing, try to understand intelligence, and the other is trying to understand intelligence and, uh, cognition in the human mind, and they're just doing it from a different set of data, uh, different set of backgrounds in the researchers that do that kind of work. And probably the same is true in, um, observational cosmology and simulation. So it's a, it's a, it's, like, a fundamentally different approach to understanding the universe. Let me use... For simulation, let me use the things I know to create a bunch of parameters and create some... Just play with it. Play with the universe. Play God-

   17. AFAnna Frebel23:58

       (laughs)

   18. LFLex Fridman23:59

       Create, create a bunch of universes and see in a way that matches experimental data. It's a, it's a fun... It's like playing Sims, but at the cosmic level.

   19. AFAnna Frebel24:08

       Yes, yes (laughs) .

   20. LFLex Fridman24:09

       (laughs) So... But... And then probably the set of terminology used there is very different and, uh, maybe you're allowed to break the rules a little bit more. Let's have, you know... Yeah. It's like the Drake equation. Yeah, you don't really know. You kind of come up with a bunch of values here and there and, and just see how it evolves, and from that kind of intuit the different possibilities, the dynamics of the evolution of a galaxy, for example. Yeah, but it's cool to play, uh, between those two, 'cause we... It seems like we understand so little about our cosmos-... so it's good to play.

   21. AFAnna Frebel24:39

       Yes. It's, it's like a big sandbox, right?

   22. LFLex Fridman24:42

       Yeah.

   23. AFAnna Frebel24:42

       And everyone kind of has their little corner and they do things, but we- we're all in the same sandbox (laughs) together at the end of the day.

   24. LFLex Fridman24:49

       (laughs) But, and that sandbox does have super powerful and, and super expensive telescopes-

   25. AFAnna Frebel24:54

       (laughs)

   26. LFLex Fridman24:54

       ... that everybody's also, uh, all the children are fighting for the resources to, to make sure they get to ask, get to ask the right questions using that, uh, big cool tool.

7. 25:03 – 34:18

   Stellar archeology

   1. LFLex Fridman25:03

      Well, can, can we actually step back on the, s- the, the, the big field of stellar archeology? Uh, what is this process? Can you just speak to it again? You've been speaking to it, but, what, what is this process of archeology in the cosmos?

   2. AFAnna Frebel25:17

      Yeah. It's, uh, it's, it's really fascinating. So, um, I mentioned the, the lesser the mass of the star, the longer it lives.

   3. LFLex Fridman25:26

      Yes.

   4. AFAnna Frebel25:27

      And, again, for reference, um, for the next dinner party, the sun's lifetime is 10 billion years.

   5. LFLex Fridman25:32

      Mm-hmm.

   6. AFAnna Frebel25:33

      So if you have a star that's .6 or .8 solar masses, then its lifetime is going to be 15 to 20 billion years.

   7. LFLex Fridman25:42

      Ouch.

   8. AFAnna Frebel25:42

      And that's, that's at an important range for our conversation. Because, again, if you assume that such a small star formed soon after the big bang, then it is still observable today.

   9. LFLex Fridman25:53

      Mm-hmm.

   10. AFAnna Frebel25:53

       You mentioned old light before.

   11. LFLex Fridman25:55

       Mm-hmm.

   12. AFAnna Frebel25:55

       Yeah, that light is like a few thousand years old, but compared to the age of these stars, it's nothing.

   13. LFLex Fridman26:01

       Mm-hmm.

   14. AFAnna Frebel26:02

       So, to me, that's young. (laughs) Uh, comes straight from, from a galaxy of, you know, it's not far, these stars are not far away. They're in our galaxy, in the outskirts. They probably did not form in the galaxy-

   15. LFLex Fridman26:16

       Mm-hmm.

   16. AFAnna Frebel26:17

       ... because, again, hierarchical assembly of a Milky Way meant-

   17. LFLex Fridman26:23

       They were eaten.

   18. AFAnna Frebel26:23

       Exactly. They're formed in a little other galaxy in the vicinity and, at some point, the Milky Way ate that, which means ab- absorbed all the stars, including, you know, these little old stars that are now in the outskirts of the Milky Way that I used to point my telescope to.

   19. LFLex Fridman26:38

       Mm-hmm.

   20. AFAnna Frebel26:38

       So what can we learn from these stars? Why should we study them? Now, these little stars are really, really efficient, um, with their energy consumption. They are still burning, for the experts, just burning hydrogen to helium in their cores, and they have done so for the past 12, 13 billion years, however old they are. And they're gonna keep doing that for another few billion years, same as the sun. The sun, sun also just does hydrogen to helium burning and will continue that for a while. Which means the outer parts of the star, uh, well, pretty much actually most of the star, that gas doesn't talk to the core. So whatever composition that, that star has, you know, in, in its outer layers is exactly the same as the gas composition from which the star formed-

   21. LFLex Fridman27:30

       Mm-hmm.

   22. AFAnna Frebel27:32

       ... which means it has perfectly preserved that information from way back then, all the way to today, and going forward. So I'm a stellar archeologist because I don't dig in the dirt to find remnants of past civilizations and, and whatnot. I dig for the star, for the old stars in the sky, because they have preserved that information from those first billion year, uh, years, um, in their, in their outer stellar atmosphere, which is what I'm observing with telescopes. So I am getting the best look at the chemical composition early on th- that you could possibly wish for.

   23. LFLex Fridman28:13

       What kind of age are we talking about here? Are we talking about something that's close to that, you know, like a 13 billion, 12, 13 billion-

   24. AFAnna Frebel28:22

       Yeah.

   25. LFLex Fridman28:23

       ... age range?

   26. AFAnna Frebel28:23

       That's what we, what we think. Now, there's a small caveat here. We cannot accurately date these stars, but we use a trick to say, "Oh, these stars must have formed as some of the earliest generations of stars." Because we need to talk about the chemical evolution of the universe and the Milky Way for a second. So I already mentioned the, uh, the pristineness of, of the universe after the big bang, right? Just hydrogen and helium. Then the first stars formed. They produced a, a, a sprinkle of heavier elements up to iron. Then the next generation of stars formed. That included, again, massive stars, that they would explode again, but also the little ones that keep on living, right? So, and then the massive ones, again, explode as supernova, so they provide, again, another sprinkle of heavier elements.

   27. LFLex Fridman29:16

       Mm-hmm.

   28. AFAnna Frebel29:16

       And so over time, all the elements in the periodic table have been built up.

   29. LFLex Fridman29:21

       Mm-hmm.

   30. AFAnna Frebel29:22

       Um, there have been other processes, for example, neutron star mergers and other exotic supernovae that have provided elements heavier than iron all the way up to uranium from very early on. We're still trying to figure out those details. But I always say pretty much all the elements f- were, were done from, like, day three. So-
8. 34:18 – 42:08

   Oldest stars

   1. AFAnna Frebel34:18

      we have a... Maybe 10 stars or so now where we're, where we are saying that they contain so little of these heavy elements that they must be second generation, because how else would you have made them? And again, I want to, I want to stress that the elements that we observe in these stars were not made by the stars themselves that we observe. They... That's just a reflection of the gas cloud. So we don't actually... I had to say that, 'cause I love stars. We don't... At the end of the day, we don't really care for the stars that we're observing. We care for the story that they're telling us about the early universe.

   2. LFLex Fridman34:52

      So yeah, so the stars are kind of a small mirror-

   3. AFAnna Frebel34:55

      Yeah.

   4. LFLex Fridman34:56

      ... in- in- into the- the- the early universe?

   5. AFAnna Frebel34:58

      Yeah. Yeah.

   6. LFLex Fridman34:59

      And so what are you detecting about those stars? Can you tell me about the process of archeology here? Like, what kind of data can we possibly get to tell the story about, um, these heavy elements on the stars?

   7. AFAnna Frebel35:10

      Yeah. It depends really on, um, what star you find.

   8. LFLex Fridman35:15

      Mm-hmm.

   9. AFAnna Frebel35:15

      Um, there are many different chemical signatures. Um, we actually pair up, these days, our, our, um, our element signatures with also kinematic information, how the star moves about the galaxy.

   10. LFLex Fridman35:29

       Mm-hmm.

   11. AFAnna Frebel35:29

       That actually gives us clues, um, as to where the star might have come from. Because again, all these old stars, uh, in the galaxy, but they are not of the galaxy.

   12. LFLex Fridman35:40

       Mm-hmm.

   13. AFAnna Frebel35:41

       That's a small but important distinction. So they all came from somewhere else.

   14. LFLex Fridman35:45

       So you can rewind back in time to kind of estimate where, where it came from?

   15. AFAnna Frebel35:48

       Yeah. So we can't really say, "Oh, it came from that and that dwarf galaxy." But interestingly enough, so I was... I'm just... Uh, just a few days ago, I submitted a paper with three women undergrads.

   16. LFLex Fridman35:58

       Mm-hmm.

   17. AFAnna Frebel35:58

       It was so good to work together. And we found a sample of stars that have very, very low abundances in strontium and barium-

   18. LFLex Fridman36:08

       Mm-hmm.

   19. AFAnna Frebel36:09

       ... so very heavy elements. And I had a hunch for a while that these stars would probably be some of the oldest-

   20. LFLex Fridman36:16

       Mm-hmm.

   21. AFAnna Frebel36:16

       ... because, as I said, heavy elements give you extra information about special events.

   22. LFLex Fridman36:22

       Mm-hmm.

   23. AFAnna Frebel36:23

       And again, finding something that's really low means it must have for... It... That must have happened either really early on or in a very special environment, right? Because we can only ever add. So if you find something that's, that's incredibly low in terms of the abundance, it... Maybe just one event contributed that, max-

   24. LFLex Fridman36:44

       Mm-hmm.

   25. AFAnna Frebel36:45

       ... so-We looked at the kinematics, how are these stars moving, and they're all going the wrong way in the galaxy.

   26. LFLex Fridman36:53

       Uh-huh.

   27. AFAnna Frebel36:54

       (laughs) How- how is that possible? Well, it is possible because consider c- well, now we come back to the proto-galaxy. The proto-galaxy was like a beehive. It just didn't really know what it was or what it wanted to become when it grew up, so... And it was absorbing all these little galaxies to grow fast. Some galaxies, some absorbed galaxies were thrown in going the main way.

   28. LFLex Fridman37:18

       Mm-hmm.

   29. AFAnna Frebel37:18

       And some came in the wrong way, huh? Happens.

   30. LFLex Fridman37:22

       Yeah, it happens.
9. 42:08 – 57:41

   Metal-poor stars

   1. LFLex Fridman42:08

      So there's this term of metal-poor stars.

   2. AFAnna Frebel42:11

      Yes.

   3. LFLex Fridman42:11

      So most of these old stars are going to be metal poor.

   4. AFAnna Frebel42:14

      Yes. I- I search for the most metal-poor stars.

   5. LFLex Fridman42:16

      And what does that... Can we just define that?

   6. AFAnna Frebel42:18

      Yeah, what does that mean? (laughs)

   7. LFLex Fridman42:19

      What does that mean?

   8. AFAnna Frebel42:20

      I don't know who came up with this. I would- I would love to know, but, um, the universe is a complicated place. So-

   9. LFLex Fridman42:28

      That's a good start.

   10. AFAnna Frebel42:28

       ... many decades ago, someone clever came up with the idea to say, "Let's simplify things a little bit. Let's call hydrogen X, helium Y, and all the other elements combined metals Z." (laughs)

   11. LFLex Fridman42:41

       Okay. Okay.

   12. AFAnna Frebel42:44

       (laughs) Oh. When- when I give public talks I always ask, "Is there a chemist in the audience?"... let me just tell you, neon is a wonderful metal. (laughs)

   13. LFLex Fridman42:53

       (laughs)

   14. AFAnna Frebel42:53

       And they're like, "Oh my God." (laughs) "What's she saying?" But-

   15. LFLex Fridman42:56

       Yeah.

   16. AFAnna Frebel42:56

       ... I'm an astronomer. I'm, I'm not a chemist so I'll get away with it. So if you just roll with it for a moment-

   17. LFLex Fridman43:02

       Mm-hmm.

   18. AFAnna Frebel43:02

       ... all the elements except hydrogen and helium are called metals. Now if we look again at chemical, or the concept of chemical evolution, it means more and more of all the ha- elements, everything hy, higher than hydrogen and helium, gets produced slowly but surely by different types of stars and events. So that's a s- you know, a monotonously increasing function.

   19. LFLex Fridman43:26

       Mm-hmm.

   20. AFAnna Frebel43:27

       Um, and so we look for the stars that have the least amounts of heavy elements in them, because that means we are going further and further back in this process, in that function, almost all the way to the very beginning. And that is the first stars, right? They, they started that, that process. That's why I said it was such an important, um, transition phase, because it, things were p- w- we call, you know, the, the post-Big Bang universe pristine just hydrogen and helium, and after that, the mess started. (laughs)

   21. LFLex Fridman43:58

       Mm-hmm.

   22. AFAnna Frebel43:58

       As soon as you add elements to it, things kinda get a little out of hand. That, that's, that ends in this beautiful variety that, that we have everywhere these days.

   23. LFLex Fridman44:09

       Yeah. And you're looking at the very early days of the introduction of the variety.

   24. AFAnna Frebel44:12

       Yes.

   25. LFLex Fridman44:13

       Okay?

   26. AFAnna Frebel44:13

       Exactly. When it was a l- still a little bit more organizable. (laughs)

   27. LFLex Fridman44:19

       Mm-hmm.

   28. AFAnna Frebel44:19

       But the, the variety of different types of metal-poor stars we have is stark. Um, many different types of stars, many patterns we have sort of identified, but there are still crazy ones out there that we're still trying to kind of fit in.

   29. LFLex Fridman44:34

       So what kind of stars have been discovered? So you've, uh, already a while ago, uh, helped discover the star HE1327-2326. Great name.

   30. AFAnna Frebel44:46

       Yes. (laughs)
10. 57:41 – 1:02:37

    Neutron capture

    1. LFLex Fridman57:41

       nothing. So what about HE 1523? What's exciting? A red, a red giant star.

    2. AFAnna Frebel57:49

       Yes.

    3. LFLex Fridman57:50

       Uh, that's another one of your babies.

    4. AFAnna Frebel57:51

       Yes. (laughs)

    5. LFLex Fridman57:52

       13.2 billion years old.

    6. AFAnna Frebel57:55

       Uh, yeah. Um, so that one isn't quite as iron deficient as the other one, so probably not a second generation star, but easily second, third, f- uh, sorry, third, fourth, fifth or so. We, we can't really pin it down, but that's also not super important for us. What, what is important is that that star has a very different chemical composition in a sense that, yes, we have all the elements up to iron there. They have sort of normal ratios, uh, which means kind of the same as most other old stars and not too different from the sun, or at least, you know, different in quantifiable ways. Um, but it has this huge overload of very heavy elements. And what was so nice about that star in particular was that I could measure the thorium and the uranium abundance.

    7. LFLex Fridman58:49

       Mm-hmm.

    8. AFAnna Frebel58:50

       And, uh, again, that was the, the second of its kind, um, but the uranium abundance was, um, could be more well determined, so we had a, a better grasp on that. Now, why are thorium and uranium interesting? Um, they are radioactive elements.

    9. LFLex Fridman59:07

       Mm-hmm.

    10. AFAnna Frebel59:08

        They ha- they decay. Uh, thorium has a half-life of 14 billion years, I believe, and uranium of 4.7, which, uh, you know, to folks on, us on Earth is a really long time, but those kind of timelines are really good when you want to explore the early universe. (laughs) So there, there are two questions now that, that kind of come to mind. Where do these elements come from?

    11. LFLex Fridman59:36

        Mm-hmm.

    12. AFAnna Frebel59:36

        And what, what do they tell us, right? And, um, these, as we know, these heavy elements are made in a specific process. It's a neutron capture process usually referred to as the r-process for rapid neutron capture process. We talked about seed nuclei before, right? So we still don't exactly know where this process can occur. So you have, let's say, uh, a lone iron atom somewhere, and it, it is in an environment where you have a strong neutron flux.

    13. LFLex Fridman1:00:09

        Mm-hmm.

    14. AFAnna Frebel1:00:09

        Which means then must be lots of neutrons around. And, again, when we talk about the site, we can (laughs) surmise and ponder where, where that might be the case. Um, but you have this iron atom and you bombard it with neutrons, and you do it incredibly fast. Now, what happens in the process? That iron atom, you know, you collect lots of neutrons, it becomes really big-

    15. LFLex Fridman1:00:31

        Mm-hmm.

    16. AFAnna Frebel1:00:31

        ... and unstable. So it's a heavy neutron-rich nucleus that wants to decay (laughs) because it's not stable. It's way too big. Um, and so let's say you add only one neutron to it, that would already make it unstable, so it will then... It has a characteristic decay time that's called the, the-... beta decay timescale. So it will decay to a stable nucleus. So the neutron will convert to a proton, and that makes it stable. If you now bombard lots and lots and lots of neutrons onto that seed nucleus within that timescale of the beta decay, that's how you get to this huge, fat neutron-rich nucleus that then wants to decay, right? So the r... The rapid process is you have your seed nuclei, they get bombarded, you create these, these really heavy neutron-rich nuclei. They're heavier than uranium even. The neutron flux stops, and then all these heavy neu- nuclei, they decay in... And they make all these stable isotopes that, that we know of, all the way up to thorium and uranium.

    17. LFLex Fridman1:01:39

        So that rapid nuclei-

    18. AFAnna Frebel1:01:40

        Yeah.

    19. LFLex Fridman1:01:41

        ... decay is what creates all the ..........................

    20. AFAnna Frebel1:01:42

        Correct. And the whole thing is done within two seconds.

    21. LFLex Fridman1:01:46

        (laughs)

    22. AFAnna Frebel1:01:47

        (laughs) So just to add to the rapid here, (snaps fingers) in literally the snapping of my hand, it's, it's all there. In my talks, I often... I have this nice simulation that, that illustrates, um, you know, this, this creation of these ra- of these heavy nu- neut- uh, nuclei. And I always say, "This is the only simulation you will ever see that's slower than real time."

    23. LFLex Fridman1:02:10

        (laughs)

    24. AFAnna Frebel1:02:11

        Because in astronomy, you know-

    25. LFLex Fridman1:02:12

        Yeah.

    26. AFAnna Frebel1:02:12

        ... we show, "Oh, this is how a galaxy forms, 13 billion years in 30 seconds." (laughs) Really short, right? This is the opposite. Me showing you this, the elements are already long, long made.

    27. LFLex Fridman1:02:24

        So where and when does this happen, does this process happen?

    28. AFAnna Frebel1:02:26

        So you need the strong neutron flux.

    29. LFLex Fridman1:02:29

        Mm-hmm.

    30. AFAnna Frebel1:02:31

        The-
11. 1:02:37 – 1:08:06

    Neutron stars

    1. AFAnna Frebel1:02:37

       right? So where do you find lots of neutrons in the universe? So it's neutron stars, right? Neutron stars form in the making of supernovae, of the explosions. Okay, so maybe some of this heavy material gets sort of made in the making of the supernova explosion and then gets expelled. Or you have neutron stars. So the, you know, if the neutron star survi-... I mean, usually that's the leftover of a supernova. If you have two from a binary pair... So stars usually actually show up in pairs. And so it's not too unusual to, um, create, um, a pair of, of neutron stars that will still orbit each other after both of their progenitor stars have exploded. And those two neutron stars will orbit each other diligently. But as we know now, thanks to LIGO, the gravitational wave observatory... Uh, I mean, we know already that before but now it's been measured by LIGO, is that these two neutron stars, they will orbit each other for, like, forever. But in the process, they will, they will lose energy.

    2. LFLex Fridman1:03:43

       Mm-hmm.

    3. AFAnna Frebel1:03:44

       So that, that orbit is what we call... The orbit decays. And eventually the two neutron stars will merge, and that results in a, in an explosive event that has roughly the energy of a supernova.

    4. LFLex Fridman1:03:57

       Mm-hmm.

    5. AFAnna Frebel1:03:58

       But, uh, the process is completely different. And the cool thing is, when these two neutron stars collide, they produce a gravitational wave signature. Because neutron stars are super dense objects, they are like giant atomic nucleuses, so there's a lot of interesting physics happening already. And so if you basically form a super neutron star-

    6. LFLex Fridman1:04:20

       Mm-hmm.

    7. AFAnna Frebel1:04:21

       ... by smashing two into each other, uh, more interesting physics happens, and that means that there's this ripple sent out, you know, into the space, uh, the, you know, the spacetime continuum basically, you know, the, the... What do people say? The, the ripples of spacetime, you know, it's like-

    8. LFLex Fridman1:04:39

       Yes.

    9. AFAnna Frebel1:04:39

       It's like you drop a, a, a rock into water, right?

    10. LFLex Fridman1:04:41

        Yeah.

    11. AFAnna Frebel1:04:41

        You see the waves coming. So that's exactly what happens when two, two neutron stars, uh, merge. And this is neutrons galore, right? It's really violent to smash two neutron stars, you know, so... That are so dense already into each other. And, um, they... In, in 2017, one of these events occurred, and the LIGO and VIRGO gravitational wave observatories, they, uh, detected that. And then the astronomers pointed their telescopes in that direction, and they indeed observed what we call the electromagnetic counterpart. So there was something seen in the sky that faded over the course of two weeks, and that light curve, that light was exactly what you get when you ha- create all these heavy neutron-rich nuclei in the r-process, and then the neutron flux stops, and then it takes about two or three weeks for most of them, of these nuclei, to decay to stability.

    12. LFLex Fridman1:05:42

        Mm-hmm.

    13. AFAnna Frebel1:05:43

        So we saw, the astronomers saw in this electromagnetic counterpart the nucleosynthesis of heavy elements occurring, and that's, that's just-

    14. LFLex Fridman1:05:55

        That's amazing.

    15. AFAnna Frebel1:05:55

        ... awesome. (laughs)

    16. LFLex Fridman1:05:56

        So that-

    17. AFAnna Frebel1:05:57

        So awesome. (laughs)

    18. LFLex Fridman1:05:57

        That's the electromagnetic counterpart to the gravitational waves that were detected with-

    19. AFAnna Frebel1:06:01

        Yes.

    20. LFLex Fridman1:06:02

        ... uh, two neutron stars-

    21. AFAnna Frebel1:06:03

        Yes.

    22. LFLex Fridman1:06:04

        ... colliding aggressively, violently to create a s- super neutron star, and that's where you get all the neutrons and neutron flux somehow and then-

    23. AFAnna Frebel1:06:14

        Yes. Yes.

    24. LFLex Fridman1:06:14

        ... that... The, the whole shebang that happens in two seconds and creates a bunch of ..........................

    25. AFAnna Frebel1:06:18

        Yeah. So that confirmed that one of the sites, for sure, is for the r-process to occur as neutron star mergers. Interestingly enough, I have to mention this here, a year prior, in 2016-

    26. LFLex Fridman1:06:30

        Mm-hmm.

    27. AFAnna Frebel1:06:31

        ... my former grad student, uh, Alex Ji, and I, we discovered a small dwarf galaxy-

    28. LFLex Fridman1:06:37

        Mm-hmm.

    29. AFAnna Frebel1:06:39

        ... that is currently orbiting the Milky Way, it's called Reticulum Two, that was full of ancient iron-deficient stars-

    30. LFLex Fridman1:06:47

        Mm-hmm.
12. 1:08:06 – 1:12:46

    Dwarf galaxies

    1. AFAnna Frebel1:08:06

    2. LFLex Fridman1:08:06

       Can you speak to what a dwarf galaxy is? Can you speak to what this Reticulum Two dwarf galaxy is that is orbiting the Milky Way galaxy?

    3. AFAnna Frebel1:08:13

       Yeah. (laughs)

    4. LFLex Fridman1:08:13

       It's going to be eaten by it, presumably, or it's separate from-

    5. AFAnna Frebel1:08:15

       It, it totally is going to be eaten. (laughs)

    6. LFLex Fridman1:08:17

       'Kay.

    7. AFAnna Frebel1:08:17

       I can't tell you exactly when. Um, uh, yeah, the, the Milky Way remains surrounded by dozens of small dwarf galaxies, and they are collections of stars. Um, some of them, uh, we call them ultra-faint dwarf galaxies because they now only contain, I don't know, a few thousand stars. Um, very, very faint.

    8. LFLex Fridman1:08:37

       They're still detectable?

    9. AFAnna Frebel1:08:39

       Uh, y- yes, because they're fairly close, and, and we detect actual individual stars in them.

    10. LFLex Fridman1:08:44

        Ah.

    11. AFAnna Frebel1:08:45

        So I've observed some of the, the faintest stars-

    12. LFLex Fridman1:08:47

        Oh, wow.

    13. AFAnna Frebel1:08:48

        ... you know, you possibly observe with current telescopes in, in these dwarf galaxies because I was like, "I need to know what the chemical composition is," because th- they are leftovers from the early universe, right?

    14. LFLex Fridman1:08:58

        Yeah.

    15. AFAnna Frebel1:08:59

        They, they did not get eaten, so they're still in their native surroundings.

    16. LFLex Fridman1:09:03

        Mm-hmm.

    17. AFAnna Frebel1:09:03

        I, I go- it's like getting the lions in the wild, right?

    18. LFLex Fridman1:09:06

        Mm-hmm.

    19. AFAnna Frebel1:09:06

        I, I go to study those-

    20. LFLex Fridman1:09:08

        Yeah.

    21. AFAnna Frebel1:09:08

        ... and compare to the counterparts that got eaten and are now in the Milky Way, and so I-

    22. LFLex Fridman1:09:14

        So presumably most of those stars, if not all of those stars, in that dwarf galaxy are really ancient?

    23. AFAnna Frebel1:09:19

        They're all really ancient because actually, as it turns out, if you have a small galaxy, um, there, there was a process early on in the universe called re-ionization that kind of heated up everything.

    24. LFLex Fridman1:09:31

        Mm-hmm.

    25. AFAnna Frebel1:09:31

        And together with some supernova explosions in an early shallow, you know, bound system, all these little systems lost their gas. It was sort of blown out or it, it simply evaporated, or both, probably both.

    26. LFLex Fridman1:09:47

        Mm-hmm.

    27. AFAnna Frebel1:09:47

        Um, and so these systems have been unable to continue to form stars since.

    28. LFLex Fridman1:09:53

        Mm-hmm.

    29. AFAnna Frebel1:09:53

        So it's, it's, it's the best for us stellar archaeologists that you could hope for, because it's a whole bunch of stars still sitting there. It's not just one. It's a whole bunch of them still sitting there ever since, and nothing has, (laughs) literally nothing has happened to them. They have-

    30. LFLex Fridman1:10:10

        So-
13. 1:12:46 – 1:41:03

    Star observation

    1. LFLex Fridman1:12:47

       It'd be amazing if we could talk about the observational aspect of this, the tools of observation. So what telescopes have you used, do you use?... and what does the data look like? And, uh, I think I've read a few interesting stories about the actual process of day-to-day observation, a bunch of, uh, probably late nights.

    2. AFAnna Frebel1:13:06

       Well, yeah. Astronomers are doing it all night long, so (laughs) -

    3. LFLex Fridman1:13:09

       Well, yeah, can you expl-

    4. AFAnna Frebel1:13:10

       ... we have lots of late nights. (laughs)

    5. LFLex Fridman1:13:11

       Can, can you explain the all-night-long aspect of it?

    6. AFAnna Frebel1:13:13

       Um, well, let me start by saying, uh, I mostly these days use the Magellan Telescopes in Chile. They are 6.5 meter telescope, which means the, the mirror diameter is 6.5 meter.

    7. LFLex Fridman1:13:25

       Mm-hmm.

    8. AFAnna Frebel1:13:26

       Um, that's not the largest that is out there, but it, it's among the largest. And, um, I use a spectrograph because I'm a spectroscopist. I don't take pictures. (laughs)

    9. LFLex Fridman1:13:37

       Mm-hmm.

    10. AFAnna Frebel1:13:38

        Um, and, uh, that particular spectrograph at that telescope is actually, um, unusually efficient, so it kind of makes up for the fact that the mirror isn't as large in, uh, let's say the-

    11. LFLex Fridman1:13:49

        Mm-hmm.

    12. AFAnna Frebel1:13:49

        ... 8 meter telescopes from the Europeans or so. So I'm very happy with that.

    13. LFLex Fridman1:13:54

        Efficiency meaning?

    14. AFAnna Frebel1:13:55

        How many photons get collected sort of per time unit.

    15. LFLex Fridman1:13:58

        Sure.

    16. AFAnna Frebel1:13:58

        Because we... That, that's always the, the limiting factor. Um, uh, prior to the pandemic, we would travel to Chile to do our observations.

    17. LFLex Fridman1:14:12

        Mm-hmm.

    18. AFAnna Frebel1:14:12

        Um, those telescopes are the... That's the last observatory where people were sort of supposed to travel there and take their own observations.

    19. LFLex Fridman1:14:19

        Mm-hmm.

    20. AFAnna Frebel1:14:19

        Most other observatories basically have staff there by now who take the observations for you.

    21. LFLex Fridman1:14:26

        So there's the directly, the scientists are, uh, specifying where to point the telescope and then sitting there-

    22. AFAnna Frebel1:14:33

        Yeah.

    23. LFLex Fridman1:14:33

        ... and collecting the data, making sure the data's collected well, the cleaning of the data, the, what, offloading of the data, all that kind of stuff.

    24. AFAnna Frebel1:14:39

        Yeah, so it's mostly done for them.

    25. LFLex Fridman1:14:41

        Yeah.

    26. AFAnna Frebel1:14:42

        Um, obviously, that's super convenient (laughs) , but it also takes, takes away a central part of what the work of an astronomer is, which is data collection (laughs) . Right? We don't have an experiment in the basement where we can go day and night or whenever we please, um, and ask a certain question of the apparatus.

    27. LFLex Fridman1:15:03

        Mm-hmm.

    28. AFAnna Frebel1:15:03

        Right? "Let's turn this knob and see what happens. Let's turn that knob and see what happens." No, you know, we, we only have one experiment-

    29. LFLex Fridman1:15:11

        Mm-hmm.

    30. AFAnna Frebel1:15:12

        ... uh, which is the universe, and we, what we see is what we get. (laughs) And I think it's, it's so important to, to take an active role in that. So I really loved going to the observatory. I've taken many students there over the years to, to teach them and to just show them what it means to, to be an astronomer. Because you, you go to the, these remote mountaintops, and it's such a magical environment, and you wait there, you know, for the sun to go down, and then you get ready, and you look outside, and it's, it's such a serene environment. Um, it's, it's a little bit out of this world. (laughs)

Episode duration: 2:18:49