YouSaid · the spoken record

Sara Walker

lines on the record

215

first

2024-06-13

most recent

2024-06-13

sittings or episodes

1

sources

podcast

Every line below is reproduced as it was said and linked to the record it came from. Nothing here is summarised or generated. Directory · Search · Corrections

1. “Yeah. But the other way I think about it is there is probably, hopefully life out there. So like I do work on life detection efforts in the solar system and I'm trying to help with the habitable worlds observatory mission planning right now and working with like the biosignatures team for that, like to think about exoplanet biosignatures. So like I have some optimism that we might find things, but they're the challenges that we don't know the likelihood for life, like which is what you were talking about. So if I get to a more grounded discussion, what I'm really interested in doing is trying to solve the origin of life so we can understand how likely life is out there. So I don't think that I think that the problem of discovering alien life and solving the original life are deeply coupled and in fact are one and the same problem. And that the first contact with aliens.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

2. “Yeah. So there might be lots of aliens out there. Maybe that's an explanation for all the singularities. They're all pinched off causal structures that virtualize their reality and kind of broke off from us.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

3. “No, I don't either. So that's kind of my fear. So I'm not sure I'm agreeing with what I say. I'm just saying like this is one sort of conclusion. And, you know, like in my most sort of like, it's interesting because I don't do psychedelic drugs. But when people describe to me, like your thing with the faces and stuff and like I have, you know, had a lot of deep conversations with friends that have done psychedelic drugs for intellectual reasons and otherwise. But I'm always like, oh, it sounds like you're just doing theoretical physics. Like that's what brains do on theoretical physics. So I live in these like really abstract spaces. Most of the time, but there's also this issue of extinction, right? Like extinction events are basically pinching off an entire causal structure, the one of these like, I'm going to call them time crystals. I don't like know what, but there's like these very large objects in time pinching off that whole structure from the rest of it. And so it's like if you imagine that sort of same thing in the universe, I once thought that sufficient.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

4. “It might be the case that sufficiently evolved biospheres kind of virtualize themselves. And they internalize their universe in their sort of temporal causal structure and they close themselves off from the rest of the universe.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

5. “Slower as a function of time. And so it would be able to run indefinitely even against an exponentially expanding universe because it would just run exponentially slower. And so I guess part of what I'm doing in my brain is putting those two things together along with this idea that we are building if you imagine with our technology, we're now building virtual realities, right? like things we actually call virtual reality, which required four billions of years of history and a whole bunch of data to basically embed them in a computer architecture. So now you can put like, you know, an Oculus headset on and think that you're in this world, right? And what you really are embedded in is in a very deep temporal structure. And so it's huge in time, but it's very small in space. And you can go lots of places in the virtual space, right? But you're still stuck in like your physical body and like sitting in the chair. And so, you know, part of it.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

6. “There's a couple ideas that are embedded here. So, one of them comes again from Paul. He wrote this book years ago about, you know, like the eerie silence and why we're alone. And he concluded the book with this idea of quintelligence or something. But like this idea that really advanced intelligence would basically just build itself into a quantum computer and it would want to operate in the vacuum of space because that's the best place to do quantum computation. It would just like run out all of its computations indefinitely, but it would look completely dark to the rest of the universe. And I don't think as typical, like I don't think that's actually the right physics, but I think something about that idea as I do with all ideas is partially correct. And Freeman Dyson also had this amazing paper about how long life could persist in a universe that was exponentially expanding. And his conception was like, if you imagine analog life form, it could run slower and slower and slower and slower.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

7. “Virtual as sort of a play on virtual reality and like simulation theories, but virtual also in a sense of, you know, we talk about virtual particles in particle physics, which they are very critical to doing calculations about predicting the properties of real particles, but we don't observe them directly. So what I mean by virtual here is virtual reality for me things that appear virtual, appear abstract are just things that are very deep in time in the structure of the things that we are. So if you think about you as a four billion year old object, the things that are part of you, like your capacity to use language or think abstractly or have mathematics are just very deep temporal structures. That's why they look like they're informational and abstract is because they're like they're existing in this temporal part of you.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

8. “Packed into this. And I think this is also embedded in sort of the virtualization of our technologies or the abstraction of language and all of these things. These things that seem really abstract are just really deep in time. And so what that looks like is you have a planet that becomes increasingly virtualized. And so it's getting bigger and bigger in time, but not really expanding out in space and the rest of space is like kind of moving away from it. Again, it's a sort of exponentially receding horizon. And I'm just not sure how far into this evolutionary process something gets if it can ever see that there's another such structure out there.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

9. “There's the universe expanding, right? It's expanding in space, but in assembly theory, it's also expanding in time. And actually, that's driving the expansion in space. And expansion in time is also driving the expansion in the sort of combinatorial space of things on our planet. So that's driving the sort of pace of technology and all the other things. So time is driving all of these things, which is a little bit crazy to think that the universe is just getting bigger because time is getting bigger. But the sort of visual that gets built in my brain about that is like the structure that we're building on this planet is packing more and more time in this very small volume of space, right? Because our planet hasn't changed its physical size in four billion years, but there's like a ton of causation and recursion and time, whatever word you want to use information.”

   2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

10. “Goes into Are you on the boundary of insane or not? But, you know, when you think about the structure of the physics of what we are that deeply, it really changes your conception of things. And, you know, going to the idea of the universe. Knowing kind of small and physical space compared to how big it is in time and how large we are, it really makes me question about whether there's any other structure that's like this giant crystalline time, this giant causal structure, like our biosphere slash technosphere is anywhere else in the universe.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

11. “Yeah, it's like instead of like, you could have the blue check, but you should have like, are you a pessimist, an optimist? Chaotic neutral. Rainbow.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

12. “Bunch of Maybe they could do better jobs with presenting material to people. Like, you know, like how things, you know, it's like usually based on interest, but I think it would be really nice if you got 10% of your Twitter feed was random stuff sampled from other places. That'd be kind of fun.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

13. “Now, I like playing with words a lot. You know, it's very funny because I know you talked about this with Lee, but people were so offended by the writing of the paper that came out last fall. And it was interesting because the ways that we use words were not the way that people were interacting with the words. And I think that was part of the mismatch where we were trying to use words in a new way. Hadn't been described adequately before, but we had to use the words that everyone else uses for things that are related. And so it was really interesting to watch that clash play out in real time for me, being someone that tries to be so precise with my word usage, knowing that it's always going to be vague.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

14. “The words that we have are inadequate to describe the things. This is why we're having a hard time talking about assembly theory because it's a newly emerging idea. And so I'm constantly playing with words in different ways to try to convey the meaning that is actually behind the words. But it's hard to do.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

15. “But you don't have a lot of room, obviously, as a speaker of a given language, you don't have a lot of room with a given word to wiggle, but you do have a certain amount of room to push the meanings of words. And I do this all the time, and you have to do it with the kind of work that I do because if you want to discover an abstraction, like some kind of concept that we don't understand yet, it means we don't have the language. And so.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

16. “Well, this is why you can play with language so much, actually. So, words don't really carry meaning, it's just about how you lace them together.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

17. “So I said before, like right now, I think the origin of life is a continuous process on earth. Like, I think this idea of combinatorial spaces that are biosphere generates not just chemistry, but other spaces often cross this threshold where they then allow themselves to persist with particular regular structure over time. So language is another one where the space of possible configurations of the 26 letters of the English alphabet is astronomically large, but we use with very high regularity certain structures. And then we associate meaning to them because of the regularity of like how much we use them, right? So meaning is an emergent property of the causation and the objects and like how often they recur and what the relationship of the recurrence is to other objects.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

18. “And what we actually instantiate as the next structures that get built in the biosphere, it's not completely deterministic because the space of future possibilities is always larger than the space of things that exist now.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

19. “Yeah, it is in part an accident because I think some of the structure that gets generated is driven a bit by randomness. I think a lot of it, so, you know, one of the conceptions that we have in assembly theory is, you know, the universe is random at its base. You can see this in chemistry, like unconstrained chemical reactions are pretty random. And then, and also quantum mechanics, you know, like there's less places that give evidence for that. And deterministic structures emerge by things that couldn't causally reinforce themselves and maintain persistence over time. And so we are some of the most deterministic things in the universe. And so we can generate very regular structure and we can generate new structure along a particular lineage. But the possibility space at the sort of tips, like the things we can generate next is really huge. So there's some stochastic.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

20. “Possibilities. And so actually, as this process of increasing assembly index, it's not just that the space that these objects exist in is exponentially growing, but there are objects in that space that are exponentially receding away from us. So they're becoming exponentially less and less likely to ever exist. And so existence excludes a huge number of things.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

21. “Yeah, so the struggle of the quote, the struggle for existence is that goes all the way back to Darwin's writing about natural selection, right? So like the whole idea of survival of the fittest is everything struggling to exist, this predator prey dynamic and the fittest survive. And so the struggle for existence is really what selection is all about. And that's true. We do see things that do exist competing to continue to exist. But each time that like if you think about this space of possibilities and each time the universe generates a new structure or like an object that exists generates a new structure along this causal chain, it's generating something that exists, that never existed before. And each time that we make that kind of decision, we're excluding a huge pace.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

22. “So there was this website. I forgot what it was, but it's like a neural network that just generates a human face. And it's like this person does not exist. I think that's what it's called, right? So you can just click on that all day and you can look at people all day that don't exist. All of those people exist in that space of things that don't exist.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

23. “Life snaps into the land. It snaps. Be poetic today, but no, I think there's like a lot of random exploration. And then there's like, and then the possibility space just collapses on the structure kind of really fast that can reinforce its own existence because it's basically fighting against non-existence.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

24. “I think it's actually abrupt. I've never been able to say that in my entire career before. I've always gone back and forth about whether the origin of life was kind of gradual or abrupt. I think it's very abrupt.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

25. “Yeah, I mean, basically, we live, the more complex we get, we live in a space that is growing exponentially large. And the ways of getting to objects in the space are also growing exponentially large. And so we're this kind of recursively like stacked structure of all of these objects that are clinging onto each other for existence. And then they like grab something else and able to bring that thing into existence because it's kind of similar to them.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

26. “So, what you're talking about, if you want to look at the long way of getting to an object, as I'm increasing the assembly index of an object, I'm moving deeper and deeper into an exponentially growing space. And it's actually also the case that the sort of typical path to get to that object is also exponentially growing with respect to the assembly index. And so if you want to try to make a more and more complex object and you want to do it by a typical path, that's actually an exponentially receding horizon. And so most objects that come into existence have to be causally very similar to the things that exist because they're”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

27. “Walk would be much shorter than the short. No, if you look at objects and you so that we define something we call the assembly universe, and the assembly universe is ordered in time. It's actually ordered in the causation, the number of steps to produce an object. And so all objects in the universe are in some sense exist at a layer that's defined by their assembly index. And the size of each layer is growing exponentially.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

28. “Recursive. Yeah. So you can think of objects in assembly theory as basically recursive stacks of the construction steps to build them. They're like, it's like you take this step and then you make this object and you make it this object and make this object. And then you get up to the final object. But that object is all of that history rolled up into the current structure.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

29. “And what Lee's been able to show in the lab with his team is that for organic chemistry, it's about 15 steps, and then you only see molecules that, you know, the only molecules that we observe that are past that threshold are ones that are in life. And in fact, one of the things I'm trying to do with this idea of like trying to actually quantify the origin of life as a transition in a phase transition assembly theory is actually be able to explain why that boundary is where it is. Because I think that's actually the boundary that life must cross. So the idea of going back to this thing we were talking about before about these structures that can reinforce their own existence and move past that boundary, 15 seems to be that boundary in chemical space. It's not a universal number. It will be different for different assembly spaces. But that's what we've experimentally validated so far.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

30. “Has some really radical implications as far as what you think is the nature of the physics that would describe life. And so what if assembly theory does formally is try to measure the boundary in the space of all things that chemically could exist, for example, like all possible molecules, where is the boundary above which we should say these things are too complex to happen outside of an evolutionary chain of events outside of selection? And we formalized that with two observables. One of them is the copy number of the object. So how many of the object did you observe? And the second one is what's the minimal number of recursive steps to make it? So if you start from elementary building blocks like bonds for molecules and you put them together and then you take things you've made already and build up to the object, what's the shortest number of steps you had to take?”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

31. “Deviations and like the initial state of the universe that there was some order there. I find that deeply unsatisfactory. And what assembly theory says, that's very different is that the universe is basically constructing itself. And when you get to these common editorial spaces like chemistry, where the space of possibilities is too large to exhaust them all, you can only construct things along historically contingent paths like you basically have causal chains of events that happen to allow other things to come into existence. And that this is the way that complex objects get formed is basically on scaffolding on the past history of objects making more complex objects, making more complex objects. That idea in itself is easy to state and simple, but”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

32. “Yeah, I think the first thing is, you know, that like the observation that life seems to be the only thing in the universe that builds complexity in the way that we see it here. And complexity is obviously like a loaded term. So I'll just use assembly instead because I think assembly is more precise. But the idea that like, you know, all the things on your desk here from your computer to the pen to us sitting here don't exist anywhere else in the universe as far as we know. They only exist on this planet. And it took a long evolutionary history to get to us is a real feature that we should take seriously as one that's deeply embedded in the laws of physics and the structure of the universe that we live in. Standard physics would say that, you know, all of that complexity traces back to the infinite.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

33. “And the genes and all the cells are the same, right? So the differentiation has to be. Something that's like much more about the actual like. Expression of genes over time and how they get switched on and off and also the physical environment of like the cell interacting with other cells. And there's just a lot of stuff going on.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

34. “You know what? This actually makes me think of one that's not up there, which I do find really incredibly amazing is Is the process of like the germline cell in. In organisms, like basically every living thing on this planet at some point in its life has to go through a single cell. And this whole issue of like development, like the developmental program is kind of crazy. Like, how do you build you out of a single cell? How does a single cell know how to do that? Like, you know, pattern formation of a multicellular organism obviously like evolves with DNA, but there's a lot of stuff happening there about when cells take on certain morphologies and things that people don't understand, like the actual shape formation mechanism. A lot of people study that and there's a lot of advances being made now in that field. I think it's pretty shocking, though, that like how little we know about that.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

35. “I guess if I was one of those frogs, I would think that was the most beautiful event I'd ever seen. Although, like, human childbirth is not that beautiful either. Well, we come in the world so violently. It's just like it's amazing.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

36. “Oh, I've seen videos of that so gross when the babies come out Did you see that Like in person, like the baby's coming out”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

37. “So, like, for a long time, life had no sight. And then, you know, like photon receptors were invented. And then when multicellularity evolved, those cells eventually grew into eyes. And we had the multicellular eye. And then it's interesting when you get to societies like human societies that we invent even better technologies of seeing like telescopes and microscopes, which allow us to see deeper into the universe or at smaller scales. So I think that's pretty profound the way that site has transformed the ability of life to literally see the reality in which it's existing in. I think consciousness is also obviously deeply interesting. I've gotten kind of obsessed with like octopus. I don't, like, I, they're just so weird. And the fact that they evolved complex nervous systems kind of independently seems very alien.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

38. “I like sight. As an invention, because I think having sensory perception and trying to comprehend the world, use anthropocentric terms is like. A really critical feature of life, and I also, it's interesting the way that sight has complexified over time, right? So like if you think at the origin of life, nothing on the planet could see.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

39. “No, I think the Origin of Life is a continual process. That's why I'm interested in the first transition and solving that problem because I think it's the hardest. But I think it's happening all the time.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

40. “It's efficient for things to eat other things that are already alive because they don't have to go all the way back to the base chemistry.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

41. “Structure. But getting past this boundary that's not very deep in that space requires life. It's a really weird property. And it's really weird that so many abrupt things happen in chemistry at that same scale.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

42. “Into, but molecules can have more than one chiral center, and that's not the only stereosometry that they can have. So, this is one of the reasons that taxol fills 1.5 universes of space. It's all of these spatial permutations that you do on these objects that actually makes the space so huge. So the point of this sort of chiral transition that I'm pointing out is chirality is actually signature of being in a complex chemical space. And the fact that we think it's a really generic feature of chemistry and it's really prevalent is because most of the chemistry we study on earth is a product already of life. And it also has to do with this transition and assembly, this transition impossibility spaces, because I think there's something really fundamental going on at this boundary that you don't really need to go that far into chemical space to actually see life in terms of this depth and time, this depth in symmetries of objects, in terms of like chiral symmetry or this assembly.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

43. “No, it's a super interesting feature. I think chirality breaks symmetry and time, not space. So we think of it as a spatial property, like a left and right hand. But if I choose the left hand, I'm basically choosing the future of that system for all time because I've basically made And so you're actually like when you have the splitting of making a molecule that now has another form, it could have had by the same exact atomic composition, but now it's just a mirror image isometry. You're basically splitting the universe of possibilities every time.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

44. “Transition happens around the time when you start accumulating. You push your molecules to a large enough complexity that chiral molecules become very likely to form. And then there's a cascade of molecular recognition where chiral molecules can recognize each other. And then you get this sort of autocatalytic feedback and things self-reinforcing.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

45. “But if you actually look at molecules, if you look at chemical space, which is like the space of all possible molecules that people can generate, and you look at small molecules, things that have less than about 7 to 11 heavy atoms, so things that are not hydrogen, almost every single molecule in that space is a chiral, like doesn't have a chiral center. So it would be like a spoon. A spoon doesn't have it. It's the same as its mirror image. It's not like a hand that's different than its mirror image. But if you get to like this threshold boundary above that boundary, almost every single molecule is chiral. So you go from a universe where almost nothing has a mirror image form. There's no mirror image universe of possibilities to this one where every single structure has pretty much a mirror image version. And what we've been looking at in my lab is that it seems to be the case that the original life trend”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

46. “Is the same for left and right handed. So you have to have some kind of symmetry breaking where you go from these chemistries that seem entirely equivalent to only having one chemistry takeover as the dominant form. And for a long time, I had been really, I actually did my PhD on the origin of chirality. I was working on it as like a symmetry breaking problem in physics. This is how I got started in the origin of life. And then I left it for a long time because I thought it was like one of the most boring problems in the original life. But I've come back to it because I think there's something really deep going on here related to this like combinatorial explosion of the space of possibilities. But just to get to that point, like this feature of this handedness has been the main focus, but people take for granted the existence of chiral molecules at all, that this property of having a handedness, and they just assume that it's just a generic feature of chemistry.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

47. “Yeah. I mean, there's also all kinds of other weird properties that happen around this kind of phase boundary. So this other project that I have in my lab is focused on the origin of chirality, which is, you know, thinking about, so chirality is this property of molecules that they can come in mirror image forms. So like just like chiral means hand. So your left and right hand are what's called non-superimposable because if you try to lay one on the other, you can't actually lay them directly on top of each other. And that's the property being a mirror image. So there's this sort of perplexing property, the chemistry life that no one's been able to really adequately explain that all of the amino acids in proteins are left-handed and all of the bases in RNA and DNA are right-handed. And yet the chemistry of these building block units, amino acids and nuclease”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

48. “They knew about them for a long time, but they didn't know that the mechanism of why that particular structure form was autocatalytic feedback. And so that's what they figured out. And this paper. And I actually think that paper is revealing some of the mechanism of the origin life transition. Because really what you see, like the origin of life is basically like, you should have a combinatorial explosion of the space of possible structures that are too large to exhaust and yet you see it collapse on this you know, really small space of possibilities that's mutually reinforcing itself to keep existing. That is the origin of life.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

49. “Theory came from him thinking about how these systems work. So he had some intuition about what was going on with this polygyny ring.”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

50. “No, but I think it goes to the deepest roots of when he started thinking about origins of life. So I mean, I don't know all his history, but like what he's told me is he started out in crystallography. And, you know, there's some things that he would just, you know, like people would just take for granted about chemical structures, that he was deeply perplexed about, like just like why are these like really intricate, really complex structures forming so easily under these conditions? And he was really interested in life, but he started in that field. So he's just carried with him these sort of deep insights from these systems that seem like they're totally not alive and just like these metallic chemistries into actually thinking about the deep principles of life. So I think he already knew a lot about that chemistry and he also, you know, assembled”

    2024-06-13 · Lex Fridman Podcast · #433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens · IDENTIFIED FROM THE TRANSCRIPT · source