Speaker 1: If you love iPhone, you'll love Apple Card. It's the
Speaker 1: credit card designed for iPhone. It gives you unlimited daily
Speaker 1: cash back that can earn four point four zero percent
Speaker 1: annual percentage yield. When you open a high Yield savings
Speaker 1: account through Apple Card, apply for Applecard in the wallet
Speaker 1: app subject to credit approval. Savings is available to Apple
Speaker 1: Card owners subject to eligibility. Apple Card and Savings by
Speaker 1: Goldman Sachs Bank USA, Salt Lake City Branch Member FDIC
Speaker 1: terms and more at applecard dot com. When you pop
Speaker 1: a piece of cheese into your mouth, you're probably not
Speaker 1: thinking about the environmental impact. But the people in the
Speaker 1: dairy industry are. That's why they're working hard every day
Speaker 1: to find new ways to reduce waste, conserve natural resources,
Speaker 1: and drive down greenhouse gas emissions. How is US Dairy
Speaker 1: tackling greenhouse gases? Many farms use anaerobic digesters to turn
Speaker 1: the methane from manure into renewable energy that can power farms, towns,
Speaker 1: and electric cars. Visit us Dairy dot COM's Last Sustainability
Speaker 1: to learn more.
Speaker 2: Here's a little secret. Most smartphone deals aren't that exciting.
Speaker 2: To be honest, they're barely worth mentioning. But then there's
Speaker 2: AT and T and their best deals. Those are quite exciting.
Speaker 2: They're the kind of deals that are really worth talking about,
Speaker 2: like their deal in the new Samsung Galaxy Z flip six.
Speaker 2: With this deal, you can trade in your eligible smartphone,
Speaker 2: any year, any condition for a new Samsung Galaxy Z
Speaker 2: flip six.
Speaker 3: It's so good, in fact, it will have.
Speaker 2: You shouting from the rooftops. So get yourself down a
Speaker 2: street level and learn how to snag the new Samsung
Speaker 2: Galaxy Z flip six on AT and T and maybe
Speaker 2: grab a ladder on the way home. AT and T
Speaker 2: connecting changes everything requires trade in a Galaxy s Note
Speaker 2: or Z series smartphone. Limited time offer two hundred and
Speaker 2: fifty six gigabytes for zero dollars. Additional fees, terms and
Speaker 2: restrictions apply. See att dot com, slash Samsung or visit
Speaker 2: an AT and T store for details.
Speaker 4: As a United Explorer Card member, you can earn fifty
Speaker 4: thousand bonus miles plus look forward to extraordinary travel rewards,
Speaker 4: including a free checked bag, two times the miles on
Speaker 4: United purchases and two times the miles on dining and
Speaker 4: at hotels. Become an explorer and seek out unforgettable places
Speaker 4: while enjoying rewards everywhere you travel. Cards issued by JP
Speaker 4: Morgan Chase Bank NA Member FDIC subject to credit approval Offer,
Speaker 4: subject to change. Terms apply.
Speaker 5: Daniel, it's good to see you. I have a question
Speaker 5: that I have been dying to ask you. When is
Speaker 5: physics going to unravel the deep mysteries of the universe?
Speaker 1: Wow? Right into it? Huh. Unfortunately we don't have that
Speaker 1: on our schedule exactly, and it's going to be as
Speaker 1: long as it takes.
Speaker 3: You know what.
Speaker 5: I need to do something important, but I keep putting
Speaker 5: it off. I put it on a calendar and give
Speaker 5: myself a deadline. I find that that actually makes it happen.
Speaker 5: So you should schedule it.
Speaker 1: All right, let's do it. I'm putting it on my calendar.
Speaker 1: Let's have a zoom meeting to share our ultimate enlightenment
Speaker 1: about the universe. Have about June twenty twenty nine that
Speaker 1: worked for you?
Speaker 6: Uh?
Speaker 4: You know?
Speaker 5: I feel like when you come up with budgets and timelines,
Speaker 5: you always need to multiply by at least three. So
Speaker 5: let's do something in the twenty forties, and I think
Speaker 5: you'll have enough time then so there it's scheduled, and
Speaker 5: that was easy.
Speaker 1: Yeah. Well, you know now I'm worried that scheduling our
Speaker 1: ultimate enlightenment is going to lead us right into the
Speaker 1: Hitchhiker's Guide to the Universe.
Speaker 3: Trap, like I'm gonna forget my towel.
Speaker 1: That maybe, but more importantly, we might get the answer
Speaker 1: and have no idea what the question was.
Speaker 3: Yep, yep, that's a tough one.
Speaker 7: Hi.
Speaker 1: I'm Daniel. I'm a particle physicist and a professor at
Speaker 1: u C Irvine, and I never forget my towel.
Speaker 5: I'm Kelly Waidersmith, and my kids are always annoyed with
Speaker 5: me because I'm the only mom at the pool who
Speaker 5: always forgets the towels. And I'm a junct faculty at
Speaker 5: Race University.
Speaker 1: How can you be forgetting towels? I mean, you have
Speaker 1: these young kids, they're always making messes. I mean everybody's kids,
Speaker 1: not yours a particular. You gotta just learn to bring
Speaker 1: the towel wherever you go.
Speaker 5: Right, I am resistant to learning. I guess I should
Speaker 5: know by now, but I never All the other moms
Speaker 5: have the big bags and they've got snacks and goldfish.
Speaker 5: My kids are always like, where are the goldfish? Everybody
Speaker 5: else has goldfish, and I'm like, tell it to your
Speaker 5: shrinking a couple of years kid, I'm sorry.
Speaker 1: At least I have something to complain about, right. My
Speaker 1: wife has one of those big bags, but she doesn't
Speaker 1: just have snacks and goldfish in it. She's got all
Speaker 1: sorts of random crap in there. And my kids are
Speaker 1: always making fun of her for it until the moment
Speaker 1: where they're like, hey, mom, wait, do you have chapstick
Speaker 1: or do you have a spoon And she's like, of
Speaker 1: course I do, and she digs it out of a
Speaker 1: bag and then she's like the savior.
Speaker 3: Mom to the rescue.
Speaker 1: Are the best, absolutely and so Welcome to the podcast
Speaker 1: that celebrates moms but also asks the deepest questions in
Speaker 1: the universe. We want to know how everything works, where
Speaker 1: it all came from, how it all can possibly make
Speaker 1: sense to our squishy little brains. Welcome to Daniel and
Speaker 1: Jorge Explain the Universe, a production of iHeartRadio.
Speaker 5: So today we're going to be talking about a topic
Speaker 5: that's near and dear to my heart. I've spent many
Speaker 5: hours arguing over this question with friends, but I'll let
Speaker 5: you go.
Speaker 3: Ahead and introduce it. I'm just just wanting to preface
Speaker 3: that I'm excited.
Speaker 1: On this podcast, we talk about some of the deepest
Speaker 1: questions in the universe. How is everything made? Where it
Speaker 1: all come from? What are the tiny little quantum particles,
Speaker 1: how do they weave themselves together in order to explain
Speaker 1: this existence? And where possibly did we leave our towels.
Speaker 1: But today in the podcast, we're going to talk about
Speaker 1: something maybe even deeper, something much more personal, something closer
Speaker 1: to our experience, and that's the question of life itself.
Speaker 1: What is it? How, how can we talk about it,
Speaker 1: how can we understand it? And how possibly could we
Speaker 1: discover it on alien planets?
Speaker 3: Oh, there's nothing better than talking about biology on a
Speaker 3: physics podcast. Finally get into the good stuff.
Speaker 1: With a couple of physicists, right, And so today on
Speaker 1: the podcast, we're going to be digging into the question
Speaker 1: what is the physics of life? And we're gonna be
Speaker 1: talking to Professor Sarah Amari Walker, author of the recent
Speaker 1: book Life As No One Knows It, The Physics of
Speaker 1: Life's Emergence. How do you feel about talking about life
Speaker 1: with two physicists.
Speaker 3: Kelly wouldn't be my first choice. But no, I'm kidding.
Speaker 5: I mean I'm very excited to hear a different perspective
Speaker 5: on the question.
Speaker 1: Well, I hope you brought a towel, because this is
Speaker 1: gonna be messy. It's always fascinating when physicists try to
Speaker 1: walk into another field and explain things. And I feel
Speaker 1: like often we do that because we think maybe there
Speaker 1: is a simpler explanation, or because we think in these
Speaker 1: like fundamental grounding in the basic principles of the universe.
Speaker 1: How would you say, that's typically receives Kelly.
Speaker 5: So you say fascinating, we say maddening, because so often physicists,
Speaker 5: you know, seem to think that physics is up here
Speaker 5: and biology is a few levels below, and if you
Speaker 5: know physics, you must also know biology and maybe also chemistry,
Speaker 5: so you can just wade in and solve all the
Speaker 5: problems that the biologists are too silly to be able
Speaker 5: to figure out. And so often there's you know, a
Speaker 5: bit of condescension in the answers. I saw Freeman Dyson
Speaker 5: give a talk once about group selection that was absolutely infuriating,
Speaker 5: but because he clearly didn't understand what we were actually
Speaker 5: arguing about. But anyway, today's conversation. You know, I read
Speaker 5: life as No One Knows It by our author who
Speaker 5: we're talking to today, and I really appreciated that she
Speaker 5: did not have that condescending biology as easy attitude. She
Speaker 5: clearly appreciated the nuances and was trying to meld it
Speaker 5: with physics.
Speaker 1: As a physicist married to a biologist, I've definitely learned
Speaker 1: to treat biology with great respect good and not just
Speaker 1: for the health of my marriage, but also just intellectually
Speaker 1: because I appreciate it. And I think, you know, the
Speaker 1: dirty secret about physicists walking into biology or chemistry is
Speaker 1: that we became physicists not because we thought biology was
Speaker 1: too easy. Your chemistry was too simple, but because it's
Speaker 1: too hard. You know, we can think about simple objects
Speaker 1: and put them together to try to describe the fundamental
Speaker 1: nature of the universe, but now we need like ten
Speaker 1: to the forty objects to explain like a drop of rain.
Speaker 1: It's too complicated. I can't think about all of those
Speaker 1: things at once. That's why I let to boil things down,
Speaker 1: for like, one particle touches one other particle, and that's
Speaker 1: my whole universe.
Speaker 3: Man.
Speaker 5: I appreciate that you're trying to clean up the reputation
Speaker 5: for your community. But I don't buy it at all.
Speaker 5: But I do think that biology is complicated. You know,
Speaker 5: we got the human microbiome that didn't solve all the
Speaker 5: disease related problems we thought it was going to solve.
Speaker 5: Now we're working on the connect dome for the brain
Speaker 5: and there's just many levels.
Speaker 3: Man, it's complicated. We deserve respect.
Speaker 1: Maybe one day we'll have an explanation for the human
Speaker 1: brain that goes all the way down to the fundamental physics,
Speaker 1: but not yet. And so to take us on this
Speaker 1: journey through the physics of life, whether we can understand
Speaker 1: the nature of life, the meaning of life, how to
Speaker 1: look for life, and how maybe even to discover life
Speaker 1: on alien planets. We had a fun conversation with Professor
Speaker 1: Sarah Amari Walker about her new book Life As No
Speaker 1: One Knows It. Here's the interview. So then it's my
Speaker 1: pleasure to welcome the podcast Sarah and Mauri Walker. She's
Speaker 1: a theoretical physicist and deputy director for the Beyond Center
Speaker 1: for Fundamental Concepts and Science, as well as a professor
Speaker 1: at Arizona State University, and she's tackling some really hard
Speaker 1: questions about the nature of life and consciousness and free
Speaker 1: will using physics in her new book, Sarah, thank you
Speaker 1: very much for joining us today.
Speaker 8: Yeah, I'm terrilled to be here. Thanks for having me.
Speaker 3: We're so glad to have you here.
Speaker 1: So before we dig into the topic of your book,
Speaker 1: I just wanted to get to know you a little
Speaker 1: bit better, especially because you're writing such a fascinating book.
Speaker 1: You're tackling really big, really hard, almost philosophical questions, but
Speaker 1: you're using physics as a tool to do it. So
Speaker 1: take us back to the beginning, like what got you
Speaker 1: into physics in the first place.
Speaker 6: I did not know I wanted to be a physicist
Speaker 6: until I took my first physics class. So most of
Speaker 6: my childhood I actually thought I was going to be
Speaker 6: an artist. And I went to community college and I
Speaker 6: knew at the time I liked science, so I just
Speaker 6: took all the science classes i could, and I just
Speaker 6: fell in love with physics. I just think it's absolutely
Speaker 6: amazing to think about the universe in these really deep,
Speaker 6: abstract ways and come to understand the world in a
Speaker 6: way that is almost existentially shocking to humans in some sense,
Speaker 6: because it's so different than the way that we thought
Speaker 6: it was, and the set of broad regularities that physics
Speaker 6: reveals I think are really beautiful, And I guess I
Speaker 6: was really excited about transforming something about the way that
Speaker 6: we think about the world and the way that physics
Speaker 6: does that.
Speaker 8: So I decided I wanted to be a physicist.
Speaker 1: Awesome. So we just had an episode recently about thinking
Speaker 1: like a physicist what that means, and had a little
Speaker 1: disagreement with Jorge about whether physicists think differently than other scientists.
Speaker 1: And so you say you're drawn to physics in particular
Speaker 1: because of the way they think about the world. How
Speaker 1: is that different? How does a physicist think about the
Speaker 1: universe different than a biologist?
Speaker 6: Yeah, and I'm not even sure if it comes down
Speaker 6: to training or who gets attracted to different fields. So
Speaker 6: I actually asked this question myself. But for me, I
Speaker 6: think a lot of the discussion about what physics is
Speaker 6: is mostly about what physics studies and not what physics
Speaker 6: is as a discipline. And so for me, when I
Speaker 6: think about the history of physics and also what I'm
Speaker 6: trying to do as a physicist, moving into territory that's
Speaker 6: traditionally not thought of as physics. You know, the thread
Speaker 6: I see there that I think is the commonality of
Speaker 6: like what I think the core of physics is is
Speaker 6: building new and abstract explanations for the world around us.
Speaker 6: So I think physics to me is getting to like
Speaker 6: the very root of like the most fundamental explanations, and
Speaker 6: that process of doing that is you know, very unique
Speaker 6: to physics, I think is a discipline relative to other sciences.
Speaker 6: I think other sciences also do that, but I think
Speaker 6: the kind of training and the way that we're taught
Speaker 6: to think and trying to embed these sort of abstract
Speaker 6: universal ideas in mathematics that are so broad, is pretty.
Speaker 8: Unique to what we call physics.
Speaker 6: Now, whether it will stay that way and it doesn't
Speaker 6: become sort of more universal to the rest of science,
Speaker 6: or even if that's the best way of doing science,
Speaker 6: as you know, a whole other.
Speaker 8: Subject of debate.
Speaker 6: But for me, that's the essence of what physics is
Speaker 6: and why I still identify as a physicist, even though
Speaker 6: the problems I study are so different than what has
Speaker 6: traditionally been studied in physics.
Speaker 5: When you've taken on a particularly in my mind, complicated
Speaker 5: questions to tackle, so my training is as a biologist
Speaker 5: and in grad school, like the thing that you stay
Speaker 5: up late drinking and talking about is you know what
Speaker 5: is life? And how do you define species? Those are
Speaker 5: like the two questions where at the end we're all like,
Speaker 5: I don't know. Nature doesn't fit into categories, and we
Speaker 5: all laugh and go out dancing. And so what different
Speaker 5: perspective does a physicist have on that question? And why
Speaker 5: do we need an answer to this question as opposed
Speaker 5: to the hand wavy nature doesn't fit into nice categories,
Speaker 5: let's just move on.
Speaker 3: Why do we need to do better than that?
Speaker 6: So I love the resolution that nature doesn't fit into categories,
Speaker 6: and so I love that that's like part of the conclusion.
Speaker 6: I think that's actually a brilliant insight, because I think
Speaker 6: we have a tendency to put problems in boxes, because
Speaker 6: certain disciplines might become more adept to answering certain aspects
Speaker 6: of questions. But there are some questions on the frontier,
Speaker 6: like what is life that you know as a biologist,
Speaker 6: Maybe you don't need to know the answer to you
Speaker 6: because you can study biology on Earth without ever having
Speaker 6: a resolution to that question. But this gets to your
Speaker 6: point that you know there are some questions like the
Speaker 6: origin of life that require an understanding of what life is,
Speaker 6: because that is not even a precisely defined question unless
Speaker 6: we say that there's some category of nature quote unquote
Speaker 6: that is life that we're trying to explain the origin of,
Speaker 6: and the other one is alien life. Are designing completely
Speaker 6: radically new kinds of life, which I think are not
Speaker 6: really decoupled problems with this idea of like what other
Speaker 6: forms could life take besides the ones that have evolved
Speaker 6: on Earth, besides the biology that we know it?
Speaker 8: And so I think.
Speaker 6: Those questions, surprisingly enough, don't seem to have answers that
Speaker 6: fall just within the discipline of biology as it's developed,
Speaker 6: because of exactly what you're pointing out, that the boundaries
Speaker 6: of disciplines are kind of historically contingent, and there's a
Speaker 6: lot of things that necessarily need to come from chemistry
Speaker 6: or even computer science or physics or all these other
Speaker 6: different disciplines. And so one thing I've really come to
Speaker 6: notice in my career is that whatever discussion we need
Speaker 6: to have about solving that problem doesn't fit in any
Speaker 6: discipline as it's currently structured, And in some sense we
Speaker 6: might need to build a new discipline to really think
Speaker 6: about this problem because it's beyond the boundaries of like
Speaker 6: the current confines of knowledge that we've defined them so far.
Speaker 6: And that's exciting because it just shows you that disciplines
Speaker 6: are kind of.
Speaker 8: Human centric categories of nature. We might have to rewrite them.
Speaker 1: Yeah, I mean, we might argue, like, what is a
Speaker 1: physicist anyway?
Speaker 6: And people exactly about that, right, and just redefine that
Speaker 6: term too.
Speaker 8: That sounds good to me.
Speaker 1: And you begin your really fun book with this question
Speaker 1: and the sort of shocking suggestion that somebody made that
Speaker 1: life doesn't exist. You know that if we can't categorize it,
Speaker 1: if we can't define it, then maybe it doesn't exist
Speaker 1: in the end. What is your definition of life?
Speaker 8: Yeah?
Speaker 6: So in my mind I usually keep I think a
Speaker 6: running list of maybe three to ten different definitions for life,
Speaker 6: because I think pinning yourself to one too early is
Speaker 6: a bit premature when we don't understand what we're talking about.
Speaker 8: So usually my process is, you know, I really want to.
Speaker 6: Have a theory, like a theory that explains the broad
Speaker 6: patterns and regularities that we see across living forms and
Speaker 6: is deep enough to help us understand the original life.
Speaker 6: That's sort of my modality of thinking about these problems,
Speaker 6: and so I've spent most of my career trying to
Speaker 6: figure out what the structure of such a theory would be.
Speaker 6: And obviously it has to be guided by some concept
Speaker 6: of what you think life is. So it's a little circular,
Speaker 6: but you're constantly redefining everything. So I'm often very hesitant
Speaker 6: to pin one answer when people.
Speaker 8: Ask me what I think life is.
Speaker 6: But with all that caveat, I can give you kind
Speaker 6: of a conceptual framing of what I think it is,
Speaker 6: but I wouldn't want to call it a definition. And
Speaker 6: I think a lot of what the theory that we're
Speaker 6: working on in the kinds of experiments are pointing to
Speaker 6: is that life is something about how information structures mattercross
Speaker 6: space and time is one way I say it, But
Speaker 6: I think in the theory that we're building, it's much
Speaker 6: more precise to say that life is the mechanism by
Speaker 6: which the universe generates complexity. And we have a very
Speaker 6: specific way of thinking about complexity, and it becomes very
Speaker 6: historically contingent, and so I guess how the universe uses
Speaker 6: memory that builds complex things in the future might be
Speaker 6: the way I say it today, and if you ask
Speaker 6: me tomorrow, I would say something else, because we're still
Speaker 6: a work in progress about trying to get to the
Speaker 6: bottom of what it is we're actually talking about.
Speaker 5: So for a biologists, the argument almost always comes down to, well,
Speaker 5: our virus is alive or not, so using the definition
Speaker 5: that you just gave our viruses alive or not and why.
Speaker 8: Yeah, So I think there's a little bit more nuanced.
Speaker 6: So usually the way I talk about it is like,
Speaker 6: are we talking about the physics of life? Are particular
Speaker 6: instances of things that are living? And it might be like,
Speaker 6: are you talking about gravitational physics and like the curvature
Speaker 6: or space time, or are you talking about a gravitational
Speaker 6: body that was generated by these sort of fundamental mechanisms
Speaker 6: that we know that our universe works in. And I
Speaker 6: think there are slightly different categories. So when I say
Speaker 6: things are life, I mean anything that is the product
Speaker 6: of an evolutionary process and requires memory and information from
Speaker 6: the past to be able to actually make that thing
Speaker 6: exist in the present. And I think viruses are certainly
Speaker 6: that they require evolution to form, but the sort of
Speaker 6: active process of generating complexity and generating novelty and contributing
Speaker 6: to the sort of open end growth of complexity that
Speaker 6: we've observed in our biosphere. I think things that do
Speaker 6: that are alive. And I'm not sure that I would
Speaker 6: qualify a virus as an individual agent as part of
Speaker 6: that creative process, but it certainly is when you look
Speaker 6: at viruses as components of ecological systems for example. So
Speaker 6: a lot of the things with issues about life is
Speaker 6: trying to pick a scale and say this thing is life,
Speaker 6: when really what you're talking about is a much more
Speaker 6: abstract universal physics that even enables those things to exist
Speaker 6: in the first place, to be selected. I think the
Speaker 6: reason that viruses have been hard is because it's actually
Speaker 6: a category error to try to partition a boundary and
Speaker 6: around a virus and say is this alive or not
Speaker 6: when you really should be looking at the continuity of
Speaker 6: the evolutionary process and what it constructs.
Speaker 1: Yeah. Fascinating. I don't know that I agree that we
Speaker 1: need a definition of life, but I do think it's
Speaker 1: valuable to try, Like, I think we need to have
Speaker 1: the discussion in order to try to figure out what
Speaker 1: this is. Like if we agree or discuss, you know
Speaker 1: what life is that shapes the way we think about
Speaker 1: how to look for alien life and all these questions.
Speaker 1: So I think it's very valuable to dig into the
Speaker 1: question even if we don't find an answer. And from
Speaker 1: that perspective, I was really interested in the discussion you
Speaker 1: had at the beginning of your book about, you know,
Speaker 1: the sort of philosophy of what life might be. And
Speaker 1: you were going through this discussion of like panpsychism, and
Speaker 1: there's this one particular line that jumped out at me said, quote,
Speaker 1: if life is not a property of matter, and material
Speaker 1: things are what exists, then life does not exist. I
Speaker 1: was wondering if you could expand on that thought. You know,
Speaker 1: it doesn't it sort of ignore the possibility that life
Speaker 1: could just be an emergent phenomenon, as you said, an arrangement,
Speaker 1: a complexity of basic bits that are not alive.
Speaker 8: Yeah.
Speaker 6: So part of the reason that I structured things in
Speaker 6: specific ways early on was to kind of set up
Speaker 6: some things that come later in the book. And one
Speaker 6: thing I've noticed being a physicist trying to build new
Speaker 6: physics is that we take for granted things as being
Speaker 6: apps asolutely true about the universe that were actually invented
Speaker 6: by human minds trying to correlate the way that their
Speaker 6: theories behave with things they could actually measure. The example
Speaker 6: I like to give is to think about mass. It
Speaker 6: seems so obvious to us that mass is a physical
Speaker 6: property of objects, and it is a physical property we
Speaker 6: talk about in our theories of physics because we can
Speaker 6: measure it, and because Galileo rolling balls down in climbplanes
Speaker 6: and other people of his generation realized that that was
Speaker 6: the right variable to construct theories of motion. I think,
Speaker 6: of course, you can talk about life as just being
Speaker 6: an emergent property, but you're never going to get to
Speaker 6: an objective understanding of it as a physical phenomena unless
Speaker 6: you can tie it to a measurement. And therefore whatever
Speaker 6: that thing is has to become what we would call
Speaker 6: a material property in our theories of physics, because now
Speaker 6: it's something we measure that becomes a variable in our theory.
Speaker 6: Therefore it's physical. And I think this has been the
Speaker 6: thing that's really hard about thinking about the nature of
Speaker 6: life is it has forever been an epiphenomena and something
Speaker 6: we couldn't regular rise as part of a law of nature.
Speaker 8: Because we want to adopt this view that surely it's
Speaker 8: just these.
Speaker 6: Emergent informational patterns, but we can't measure them objectively. And
Speaker 6: so my point saying that if you want to reduce
Speaker 6: life that way, then life doesn't exist because you don't
Speaker 6: have an objective measurement. You don't have a way of
Speaker 6: grounding whatever you're talking about and testing it against reality
Speaker 6: and saying this is the thing that emerges when life emerges.
Speaker 1: If I could just stop you there, because I'm not
Speaker 1: sure I'm following, Like, let's take a simpler example. You
Speaker 1: know a thunderstorm. Thunderstorm is an emergent phenomenon bubbling up
Speaker 1: from the you know, the properties of particles and molecules
Speaker 1: and all this kind of stuff. Clearly thunderstorms exist, right,
Speaker 1: we agree. We can make measurements of them, their intensity,
Speaker 1: all sorts of stuff. We can ground them, we can
Speaker 1: write even some you know, mathematical expressions that describe them
Speaker 1: in some cases, How can we say thunderstorms exist and
Speaker 1: we can make physical measurements of thunderstorms, but we can't
Speaker 1: say the same thing about life.
Speaker 8: Well, what would be the measurement that you're taking about life?
Speaker 1: Though?
Speaker 6: So the question with thunderstorms is it's a good example
Speaker 6: because most of the measurements you're taking are things like
Speaker 6: wind velocity, you know, the temperature. Like these are like
Speaker 6: physical measurements you can go in and take, and then
Speaker 6: when you put those in some model of a thunderstorm,
Speaker 6: you can actually model the thunderstorm's behavior. And that same
Speaker 6: physics works if you go on another planetary body and
Speaker 6: account for differences in pressure and differences in the particular climate,
Speaker 6: you know, in that gravitational field, and things like that.
Speaker 6: The issue with life is, you know, most people want
Speaker 6: to say that, like when you're talking about chemistry, and like,
Speaker 6: life is an organizational property of chemistry. When we look
Speaker 6: at its parts, we don't see the things that we
Speaker 6: associate to life, and so therefore life is an emergent
Speaker 6: property of those parts. It's some organizational feature. But the
Speaker 6: problem is we don't have the rules to go from
Speaker 6: the atoms and the parts to that organizational feature in
Speaker 6: a universal way that would allow us to go on
Speaker 6: another planet and measure that property. It's very subjective the
Speaker 6: way that we talk about it, right, and so it's
Speaker 6: okay if it's subjective and not a material property. It
Speaker 6: might be that there is no law of physics that
Speaker 6: allows us to understand what life is. And it might
Speaker 6: be that life is not a universal category of nature.
Speaker 6: It might just be some weird emergent pattern that emerged
Speaker 6: on Earth and there's no universality to it. But the
Speaker 6: argument that I'm interested in, and the one I think
Speaker 6: that will actually help us find alien life that's out there,
Speaker 6: because life is a universal thing if it is, is
Speaker 6: that we need to figure out what are the objective properties.
Speaker 6: And when you do that, in some sense, you're making
Speaker 6: that property material in a way that it becomes measurable.
Speaker 6: And so that's sort of the interplay. Like life has
Speaker 6: not been a material property. We've had this sort of
Speaker 6: vitalism and the idea of a soul. But the question
Speaker 6: is is that actually something that we can quantify, put
Speaker 6: into a theory, and also measure so that we can
Speaker 6: actually say this is a real universal law like feature
Speaker 6: of our universe.
Speaker 5: But so then why go to life does not exist?
Speaker 5: As opposed to we don't understand it well enough yet.
Speaker 6: Because the logical conclusion of the way that much of
Speaker 6: the discussion has been is that we should assume life
Speaker 6: does not exist. So in some sense, what I'm trying
Speaker 6: to do is actually provoke, you know, like, if we
Speaker 6: run the way we talk about things to their logical conclusion,
Speaker 6: what are we really saying And is this actually what
Speaker 6: we intend to say?
Speaker 8: Or do we want to say?
Speaker 6: There's something missing from our descriptions of nature, and maybe
Speaker 6: we need to rethink from first principles what it is
Speaker 6: that we're doing. So I actually think life does exist.
Speaker 6: I was always perplexed that a lot of my colleagues,
Speaker 6: if you really listen to the words they were saying,
Speaker 6: were implying that it does not exist, and some of
Speaker 6: them even saying it outright, that like, we should just
Speaker 6: not think about the problem of defining life at all.
Speaker 6: Life is not a category of nature. It's all reducible
Speaker 6: to chemistry and physics. And I think that there's something
Speaker 6: deeply missing in what life is and why we keep
Speaker 6: asking this question? So why is it a question we
Speaker 6: ponder in bars at night. It's probably because we feel
Speaker 6: intrinsically we're missing something about, you know, the descriptions of
Speaker 6: the world around us that's pretty fundamental. So that was
Speaker 6: always my perspective. Now that might not be right, but
Speaker 6: I think the way to find out if that's.
Speaker 8: Right is try to go through the process.
Speaker 6: Of building a theory you can test against something you
Speaker 6: can measure, and trying to see if empirically you're actually
Speaker 6: getting the right results, and if you're building a theory
Speaker 6: that is all explanatory of the data that we see
Speaker 6: in the observations we can make.
Speaker 1: Right, So you're not saying I don't exist, or you
Speaker 1: don't exist, or my cat doesn't exist. You're saying that
Speaker 1: we don't have a clear and crisp definition of life
Speaker 1: that lets us do things that we typically do in
Speaker 1: physical theories, like we do with thunderstorms and we do
Speaker 1: with cats, because we can make measurements of them. We
Speaker 1: can other than just like vaguely talking about sort of
Speaker 1: fuzzy conceptual categories.
Speaker 6: Yeah, I mean, in part, you know, the book is
Speaker 6: an exercise of trying to turn a philosophical question into
Speaker 6: a scientific one.
Speaker 1: Yeah.
Speaker 6: Right, So this has traditionally been a philosophical debate because
Speaker 6: we don't have the things that we can pin the
Speaker 6: debate into measurements to actually go test what it is
Speaker 6: that we're talking about. And I think that's really the
Speaker 6: critical transition that you know, most interesting science starts as
Speaker 6: philosophical questions. And the period where the philosophy transitions to
Speaker 6: science is always deeply interesting because we're asking exactly these
Speaker 6: like really basic questions. It forces you to even ask
Speaker 6: what science is, what is a measurement?
Speaker 8: What is a theory? How do you build a new theory?
Speaker 6: Like what are we even talking about ever when we
Speaker 6: talk about things in science? So this is why it's exciting,
Speaker 6: But it is really challenging because you're confronting things that
Speaker 6: you know, we haven't known how to think about, and
Speaker 6: you're saying, let's pin ourselves down and be precise and
Speaker 6: think about it and ask, how would we actually quantify
Speaker 6: and measure this thing? And how will we build a
Speaker 6: theory that describes this thing? And if you look at
Speaker 6: the history of science, what excites me about it and
Speaker 6: why I think any of the ideas that we're doing
Speaker 6: might be on the right track is you know, every
Speaker 6: time that that process has happened in the history of physics,
Speaker 6: we come out the other side with a radically different
Speaker 6: conception of what's going on than we had before. My
Speaker 6: favorite example is like to think about you know, saying
Speaker 6: terrestrial and celestial motion are the same thing. It's like,
Speaker 6: you know, humans had been around for hundreds of thousands
Speaker 6: of years seeing the stars and the night sky and
Speaker 6: planets moving across the sky, and we never thought like
Speaker 6: that would be you know.
Speaker 8: Like the theory of gravitation.
Speaker 6: It took you know, centuries of measurement and coming to
Speaker 6: you know, track the regularities of heavenly motions and be
Speaker 6: able to get clocks that were precise enough timing to
Speaker 6: actually build into an understanding of a theory of motion
Speaker 6: and gravitation that allowed us to look up at the
Speaker 6: sky and be like, oh, those things are actually moving
Speaker 6: in the same way that things on Earth move. I mean,
Speaker 6: these are radical conceptual leaps that our species has taken,
Speaker 6: and I think to think that we're done doing that
Speaker 6: is really premature. So I get excited about life and
Speaker 6: when people say, well, isn't it just a pattern of motions,
Speaker 6: and I'm like, well, of course it is. But we've
Speaker 6: explained lots of those before in really deep and fundamental ways,
Speaker 6: so maybe we should try again.
Speaker 1: All right, I have lots more questions about this squishy topic,
Speaker 1: but first let's take a quick break. With big wireless providers,
Speaker 1: what you see is never what you get. Somewhere between
Speaker 1: the store and your first month's bill, the price you
Speaker 1: thoughts you were paying magically skyrockets. With Mintmobile, You'll never
Speaker 1: have to worry about gotcha's ever again. When Mint Mobile
Speaker 1: says fifteen dollars a month for a three month plan,
Speaker 1: they really mean it. I've used Mintmobile and the call
Speaker 1: quality is always so crisp and so clear. I can
Speaker 1: recommend it to you, So say bye bye to your
Speaker 1: overpriced wireless plans, jaw dropping monthly bills and unexpected overages.
Speaker 1: You can use your own phone with any mint Mobile
Speaker 1: plan and bring your phone number along with your existing contacts.
Speaker 1: So ditch your overpriced wireless with mint Mobiles deal and
Speaker 1: get three months a premium wireless service for fifteen bucks
Speaker 1: a month. To get this new customer offer and your
Speaker 1: new three month premium wireless plan for just fifteen bucks
Speaker 1: a month, go to mintmobile dot com slash universe. That's
Speaker 1: mintmobile dot com slash universe. Cut your wireless bill to
Speaker 1: fifteen bucks a month. At mintmobile dot com slash universe,
Speaker 1: forty five dollars upfront payment required equivalent to fifteen dollars
Speaker 1: per month. New customers on first three month plan and
Speaker 1: only speeds slower about forty gigabytes on unlimited plan. Additional
Speaker 1: Taxi speed and restrictions apply. Seement Mobile for details.
Speaker 9: AI might be the most important new computer technology ever.
Speaker 9: It's storming every industry and literally billions of dollars are
Speaker 9: being invested, so buckle up. The problem is that AI
Speaker 9: needs a lot of speed and processing power. So how
Speaker 9: do you compete without cost spiraling out of control. It's
Speaker 9: time to upgrade to the next generation of the cloud.
Speaker 9: Oracle Cloud Infrastructure or OCI. OCI is a single platform
Speaker 9: for your infrastructure, database, application development, and AI needs. OCI
Speaker 9: has fourty eight times the bandwidth of other clouds, offers
Speaker 9: one consistent price instead of variable regional pricing, and of
Speaker 9: course nobody does data better than Oracle. So now you
Speaker 9: can train your AI models at twice the speed and
Speaker 9: less than half the cost of other clouds. If you
Speaker 9: want to do more and spend less, like Uber eight
Speaker 9: by eight and Data Bricks Mosaic, take a free test
Speaker 9: drive of OCI at Oracle dot com slash strategic. That's
Speaker 9: or dot Com slash Strategic Oracle dot Com slash Strategic.
Speaker 1: If you love iPhone, you'll love Apple Card. It's the
Speaker 1: credit card designed for iPhone. It gives you unlimited daily
Speaker 1: cash back that can earn four point four zero percent
Speaker 1: annual percentage yield. When you open a high Yield Savings
Speaker 1: account through Apple Card, apply for Applecard in the wallet
Speaker 1: app subject to credit approval. Savings is available to Apple
Speaker 1: Card owners subject to eligibility Apple Card and Savings by
Speaker 1: Goldman Sachs Bank, USA, Salt Lake City Branch Member, FDIC,
Speaker 1: terms and more at applecard dot com. When you pop
Speaker 1: a piece of cheese into your mouth or enjoy a
Speaker 1: rich spoonful of Greek yogurt, you're probably not thinking about
Speaker 1: the environmental impact of each and every bite, But the
Speaker 1: people in the dairy industry are. US Dairy has set
Speaker 1: themselves some ambitious sustainability goals, including being greenhouse gas neutral
Speaker 1: by twenty fifty. That's why they're working hard every day
Speaker 1: to find new ways to reduce waste, conserve natural resources,
Speaker 1: and drive down greenhouse gas emissions. Take water, for example,
Speaker 1: most dairy farms reuse water up to four times the
Speaker 1: same water cools the milk, cleans equipment, washes the barn,
Speaker 1: and irrigates the crops. How is US dairy tackling greenhouse gases?
Speaker 1: Many farms use anaerobic digestors that turn the methane from
Speaker 1: maneuver into renewable energy that can power farms, towns, and
Speaker 1: electric cars. So the next time you grab a slice
Speaker 1: of pizza or lick an ice cream cone, know that
Speaker 1: dairy farmers and processors around the country are using the
Speaker 1: latest practices and innovations to provide the nutrient dense dairy
Speaker 1: products we love with less of an impact. Visit us
Speaker 1: dairy dot com slash sustainability to learn more. Okay, we're
Speaker 1: back and we're trying to sort through the slimy questions
Speaker 1: of the physics of life with Professor Sarah Amari Walker,
Speaker 1: author of the book Life As No One Knows It
Speaker 1: Well in terms of taking like a radical conceptual philosophical leaps,
Speaker 1: I was very excited to see you open the door
Speaker 1: to getting rid of reductionism. I mean especially as of physicists,
Speaker 1: you know, and as you described earlier, physics is so
Speaker 1: ingrained in the idea of like, let's find the microscopic
Speaker 1: explanation for everything. Start with what we hope is the
Speaker 1: fundamental and everything will bubble up from there somehow dot
Speaker 1: dot dot right. Leave that as an exercise for the engineers.
Speaker 1: But in your book you actually consider the other approach,
Speaker 1: the idea that, like, maybe not everything is determined from
Speaker 1: the smallest bits. Maybe what we see as like emergent
Speaker 1: phenomena different scales actually have their own different fundamental description that, like,
Speaker 1: you know, the universe isn't controlled by the tiniest Can
Speaker 1: you talk a little bit about that. I think that's
Speaker 1: probably a very unfamiliar concept for our listeners who are
Speaker 1: used to, especially on this podcast, hearing us talk about
Speaker 1: how tiny particles weave together to make the universe.
Speaker 6: Yeah, and I also love that view of reality. I
Speaker 6: think it's like incredibly romantic, and I was trained in
Speaker 6: that tradition. But thinking about life and really trying to
Speaker 6: ask the question whether there were universal laws of life
Speaker 6: like that speaks to me that looking for something fundamental,
Speaker 6: because it has to be universal and broadly explanatory of
Speaker 6: any life in the universe, you start to ask questions
Speaker 6: about the nature of what's fundamental. And as I already
Speaker 6: alluded to before, a lot of the ways that we
Speaker 6: think about what's fundamental are what things we can go
Speaker 6: in the lab and test that build the structure of
Speaker 6: our theories, and so some of the most precise theories
Speaker 6: we have are these ones about microscopical physical motions, but
Speaker 6: it doesn't mean that they explain everything. And one of
Speaker 6: the points that I make in the book, which is
Speaker 6: related to this sort of evolutionary progress of knowledge that
Speaker 6: we've been talking about about, like disciplines changing over time,
Speaker 6: is the notion of what's fundamental has actually changed with
Speaker 6: our theories and with our measuring devices, and so I think,
Speaker 6: you know, like the canonical example I like to give
Speaker 6: is to think about atoms, which we thought for a
Speaker 6: long time or indivisible units of matter until we build
Speaker 6: better technology and we realized they had parts. And so
Speaker 6: I'm not sure that there's really a bottom to that process.
Speaker 6: If string theory is right, obviously all the elementary particles
Speaker 6: and things we think are you know, the full description
Speaker 6: and reality are not right. But we can't validate theories
Speaker 6: that go smaller because we don't have the technology yet.
Speaker 6: So you know, that becomes a horizon of our current
Speaker 6: understanding of reality, not something that's intrinsic to reality itself.
Speaker 6: And if you flip that around and you look at
Speaker 6: what you're trying to do building a theory of life,
Speaker 6: life is built out of these what we think are
Speaker 6: fundamental building blocks. But the kinds of things that we
Speaker 6: want to understand about life are much more about how
Speaker 6: the universe builds complexity out of small parts. And it
Speaker 6: is the case that if we can think about things
Speaker 6: that we can measure there and build theories there, there's
Speaker 6: no reason to think they're not just as fundamental as
Speaker 6: these other descriptions of nature.
Speaker 8: So that's sort of like the.
Speaker 6: Baseline philosophy I'm operating from. But the sort of core
Speaker 6: of your question, I think is more about the emergence
Speaker 6: reductionism debate, not the philosophy of measurement and what's fundamental.
Speaker 6: But I think like those things are coupled, so I
Speaker 6: wanted to preface it. But the emergence reductionism, you know,
Speaker 6: Phil Anderson had this great essay which a lot of
Speaker 6: people have read and love about this idea of more
Speaker 6: is different. You know, even if you had that fundamental description,
Speaker 6: it doesn't mean that as you go to these other
Speaker 6: layers like biology and mind and technology, you're going to
Speaker 6: actually be able to recover all the features of them.
Speaker 6: And so this has been deeply perplexing. And what I
Speaker 6: suggest in the book is one of the reasons you
Speaker 6: can't go between scales, is there actually are separate laws
Speaker 6: that describe the idea of a hierarchy in the first place,
Speaker 6: that the universe is actually constructing complexity, and that time
Speaker 6: needs to be a component of that process. So if
Speaker 6: you remove you know, evolutionary time, you know, you can
Speaker 6: talk about me being an emergent property of my atoms.
Speaker 6: But I've missed almost all of the physics that's in
Speaker 6: my body. I am like the product of four billion
Speaker 6: years of evolution, and so if I want to talk
Speaker 6: about me as a fundamental structure, I need to talk
Speaker 6: about that feature, not the atoms in my body. And
Speaker 6: so it's really trying to invert the nature of like
Speaker 6: what is the thing that actually explains this. You can
Speaker 6: say I'm an emergent property, but it doesn't explain from.
Speaker 8: Those laws, those lower level laws, how I got here
Speaker 8: and why I exist.
Speaker 1: But does that mean that there is no explanation that
Speaker 1: you have to have fundamental laws at every scale or
Speaker 1: does it just mean those explanations escape us currently or
Speaker 1: our current ability to do those calculations. And in some
Speaker 1: future where we have an amazing supercomputer, we can model
Speaker 1: everything from the tiniest bits.
Speaker 6: I think it's both of the last things you said.
Speaker 6: So I think there you cannot produce things like us
Speaker 6: from the current structure the laws of physics. I don't
Speaker 6: even think if you had a super massive supercomputer you
Speaker 6: could do it. And a simple reason to cite that
Speaker 6: is it would require more computation than is available in
Speaker 6: all of the resources of the entire universe. And yet
Speaker 6: the universe builds things like us. And so I think
Speaker 6: that right there suggests that something fun mental is missing,
Speaker 6: because you could say, in principle, you could simulate it,
Speaker 6: and you could generate our conversation that we're having right now,
Speaker 6: but actually, in principle is not in principle because it's
Speaker 6: not even physically possible. So those things, to me suggest
Speaker 6: that there's a huge gap in understanding. But I also
Speaker 6: think fundamentally that the physics of what describes living things
Speaker 6: is not encapsulated in the physics that we have of
Speaker 6: gravitational fields or elementary particles or any sort of state
Speaker 6: of the art in modern physics departments. I think it's
Speaker 6: just not in those equations. And the reason I think
Speaker 6: it's not in those equations is because life is very
Speaker 6: much about the causation and time that's built into physical
Speaker 6: objects that are complex. And if you think about what
Speaker 6: the laws of physics revealed, they are often designed for
Speaker 6: specific problems, and they tell you what's universal about a
Speaker 6: set of questions like motion, for example, like all moving
Speaker 6: objects you know, can be described by mass acceleration and
Speaker 6: you don't care about the color of them or how
Speaker 6: those objects feel or other things. But that doesn't mean
Speaker 6: that those laws explain everything about every object. And so
Speaker 6: you know, the question is how many kinds of laws
Speaker 6: of physics do we need? What's the sort of universal
Speaker 6: set of things that they cover? And I think life
Speaker 6: is presenting some real challenges for the sort of current
Speaker 6: paradigm that we have in really fundamental ways.
Speaker 5: Again, as the biologist in the conversation, so I feel
Speaker 5: like what I'm hearing is that we don't really understand
Speaker 5: the physics stuff, but we know that life is something
Speaker 5: that comes about through the process of evolution. So I
Speaker 5: feel like we're back in an evolutionary biology lab. Yes,
Speaker 5: how how does a physicist study it differently? Like is
Speaker 5: the question what process results in something that natural selection
Speaker 5: can then act on? Like when we you know, put
Speaker 5: the pedal to the metal or whatever, like what do
Speaker 5: we do in a lab or on a board for
Speaker 5: with equations that's different.
Speaker 8: So this is a.
Speaker 6: Great question because ultimately, like Daniel's question, can you know
Speaker 6: what will ultimately resolve it is? Does providing a new
Speaker 6: explanation provide any new experimental tests and things we couldn't do.
Speaker 8: Otherwise because it doesn't.
Speaker 6: I could tell you, you know, I could sit here
Speaker 6: all day arguing that there's other laws of physics in life,
Speaker 6: and you know you could nod your head, Okay, Sarah,
Speaker 6: but show me the proof, right, And I've been doing
Speaker 6: this most of my career because you know, I have
Speaker 6: like some conviction it's there, but we have to do
Speaker 6: the hard work.
Speaker 8: As scientists and show that it's useful for something.
Speaker 6: And I think, I think to your question, the challenge is,
Speaker 6: you know, for the most part, we think about evolution
Speaker 6: and selection as being things that life does. But that
Speaker 6: doesn't allow us to explain the origin of life because
Speaker 6: it has to be some spontaneous fluctuation with no mechanism, right,
Speaker 6: and so or it's just a rare fluke, right, And
Speaker 6: then if it's a rare fluke, then you know, none
Speaker 6: of this discussion is necessary because it's just some thing
Speaker 6: that happened and there's no explanation for it.
Speaker 8: It was just, you know, a rare fluch event.
Speaker 6: And I think this is one of the challenges because
Speaker 6: that allows you know, intelligent design and other things to
Speaker 6: be equivalent explanations to the scientific one, because we don't
Speaker 6: have an explanation. So if you really want to explain it,
Speaker 6: you kind of have to assume. The original life is
Speaker 6: itself a process of selection and evolution. So it's the
Speaker 6: product of those kind of mechanisms, which means you need
Speaker 6: an understanding of evolution that doesn't require.
Speaker 8: A cellular architecture. And this is the main challenge, right so.
Speaker 6: Before replication, before natural selection as we understand it now
Speaker 6: in genes or the way it operates in biological populations,
Speaker 6: out of chemistry, how does an evolutionary system get constructed?
Speaker 6: And so this is really the question that we're trying
Speaker 6: to ask is how do you get complexity when there
Speaker 6: is none? And so that's where we need a new paradigm,
Speaker 6: because we need a mechanism of selection that operates starting
Speaker 6: from simple molecules building into the complexity of life. And
Speaker 6: that's really the theory that we're working on. This assembly
Speaker 6: theory is really an approach to talking about selection in
Speaker 6: the absence of like when selection emerges, how do selection
Speaker 6: actually start? And how to selection build evolutionary systems that
Speaker 6: we would recognize as evolving things. And so it's suggesting
Speaker 6: a much more universal structure to the evolutionary process then
Speaker 6: the particular things that were selected and evolved on Earth.
Speaker 6: To understanding what are the general principles of the kinds
Speaker 6: of systems that chemistry could generate that could lead to
Speaker 6: this process of evolution that we recognize. That's the question
Speaker 6: we're trying to answer, and I think that one really
Speaker 6: does demand new physical principles because you're asking out of
Speaker 6: I mean, people really don't understand how big chemical space is.
Speaker 6: It is like astronomically large. We also do a lot
Speaker 6: of stuff with drug design with the same theories that
Speaker 6: we're trying to sell the original life, which is kind
Speaker 6: of crazy. So I deal with like you know, pharmaceutical
Speaker 6: drugs and this kind of stuff. But like when keminformatics
Speaker 6: go in and they want to estimate the size of
Speaker 6: the chemical space they have to search to look for
Speaker 6: new drug like properties. It is insane it's not small,
Speaker 6: it's insanely large, you know. I think a really good
Speaker 6: example is like taxol is a molecule I use a
Speaker 6: lot of times when I give lectures that I picked
Speaker 6: up from my colleged Lee Kronin. That molecule has an
Speaker 6: molecrooid of about eight hundred and fifty three. You know,
Speaker 6: I think it has like forty seven carbon atoms or
Speaker 6: fifty three or something oxygen. Anyway, Like, if you wanted
Speaker 6: to do all the molecules with that chemical formula alone,
Speaker 6: it would fill a volume of one point five universes.
Speaker 6: So if you think about a planet generating chemical chemistry
Speaker 6: in an unconstrained way, no selection, the space of molecules
Speaker 6: that could be you know, just randomly synthesized is so
Speaker 6: astronomically large you would never expect anything complex to recur twice.
Speaker 6: And so this is kind of a key argument of
Speaker 6: the way that we constructed the theory. When you start
Speaker 6: to see things that involve a lot of constraints in
Speaker 6: the space of possibilities to get these really complex, really
Speaker 6: probable objects with a high abundance that they're happening a lot,
Speaker 6: that's evidence of selection happening and that selection is actually
Speaker 6: the physics generating those objects. But it's got to be
Speaker 6: much deeper than what we just see and involved architectures
Speaker 6: that we have, like with the cell, because that comes
Speaker 6: fairly late in new original Aye process.
Speaker 1: So I understand that the space is very large, right,
Speaker 1: Obviously there's lots of different combinations. Chemistry is complicated. But
Speaker 1: how do we know what's improbable or what's unusual because
Speaker 1: the space is so large and we haven't explored it, right,
Speaker 1: And you say, for example, like the existence of rockets
Speaker 1: in the universe is a sign of like conscious thought
Speaker 1: or whatever. But you know, how do we know them
Speaker 1: that that's the case? How do we know that other
Speaker 1: arrangements that our particular planet didn't explore don't lead to
Speaker 1: greater complexity or more interesting things existing in the universe.
Speaker 6: So your question is a good one, and I think
Speaker 6: a lot of us have sort of embedded in the
Speaker 6: way that we think about the world. And this actually
Speaker 6: comes from the way that we think about physics. It's
Speaker 6: sort of a heritage legacy actually from the eighteen hundreds
Speaker 6: and the development of statistical mechanics and the idea of
Speaker 6: spontaneous fluctuation. We have an idea in our minds that
Speaker 6: anything of arbitrarily complexity can spontaneously fluctuate into existence. And
Speaker 6: this is the whole impetus of the Boltzmann brain argument,
Speaker 6: which actually was proposed by Eddington originally as kind of
Speaker 6: a mocking of Boltzman's ideas, but then became something that
Speaker 6: physicists took very seriously and tried to put in our
Speaker 6: cosmological models. And so the challenge there is, of course,
Speaker 6: we can say, you know, a planet can make an
Speaker 6: arbitrarily complex molecule, right, I can make that statement, and
Speaker 6: it seems intuitively logical. But if I said, you know,
Speaker 6: Mars is going to generate a cell phone tomorrow, you
Speaker 6: would kind of laugh at me, right, Like that's.
Speaker 8: A silly statement.
Speaker 6: Is there really a chance that we could just find
Speaker 6: the planet Mars generating a cell phone, and like, not
Speaker 6: a cell phone, but just something equivalent amount of organization
Speaker 6: and evolutionary processes, Like a cell phone takes four billion
Speaker 6: years to make on a planet. It takes a lot
Speaker 6: of selection to get to that very specific object. It's
Speaker 6: really designed for our biology. The technology is built on
Speaker 6: our planetary resources, Like everything about that object is a
Speaker 6: direct consequence of the fact that we've had four billion
Speaker 6: years of evolution along a specific trajectory on our planet,
Speaker 6: and so to assume an object like that can just
Speaker 6: form random chance somewhere in the universe, I think is
Speaker 6: a major it's a major misstep in our reasoning.
Speaker 8: About how reality works.
Speaker 6: We have no evidence that it can actually happen outside
Speaker 6: of evolution, and so a lot of people will try
Speaker 6: to challenge the way that we're building the formalism on
Speaker 6: this idea that something complex can just be made on
Speaker 6: a planet in the absence of evolution and selection. And
Speaker 6: I can just say back to that, like, give me
Speaker 6: the evidence the universe builds a me that requires like
Speaker 6: information to specify it, because to me, what that argument
Speaker 6: would entail is actually the equivalent of intelligent designs, as
Speaker 6: the universe has the design of every object at every
Speaker 6: point in the universe. What I'm suggesting is that selection
Speaker 6: and evolution are required to build information specific to objects
Speaker 6: before they can exist.
Speaker 1: Right, And I agree with that. I'm not arguing that
Speaker 1: cell phones should appear on Mars, so that would be probable,
Speaker 1: and I appreciate that. You know, complexity comes as like
Speaker 1: the tip of the pyramid built on the base of
Speaker 1: like a huge amount of things that came before it. Absolutely,
Speaker 1: But what I'm wondering is whether we can argue that
Speaker 1: life on Earth is unusually complex. We don't know with
Speaker 1: the space of possibilities is maybe if we go out
Speaker 1: in the universe we discover, wow, we're actually quite primitive.
Speaker 1: Complexity here on Earth is where in the backwater, I
Speaker 1: mean compared to Mars. Sure, but like you were saying that,
Speaker 1: you know, what we've achieved here on Earth or what's
Speaker 1: happened here on Earth is unusually complex. But how do
Speaker 1: we know that?
Speaker 8: Oh, where's the prior?
Speaker 6: I see, so I was referencing that with respect to
Speaker 6: an abiotic prior. Imagine you don't have an evolutionary system, right,
Speaker 6: So I think we're talking cross purposes about the question.
Speaker 6: So I just want to kind of frame it precisely.
Speaker 6: So if you just look at you know, so a
Speaker 6: system that doesn't have evolutionary selection, the sort of framing
Speaker 6: that we have the key conjectures, there's a maximum complexity
Speaker 6: a non living system could build, and it can't build
Speaker 6: any more than that until selection and sort of feedback
Speaker 6: on the structure and self reproducing systems emerge. That actually
Speaker 6: constrain themselves to be able to perpetuate.
Speaker 8: Right.
Speaker 6: What you're asking is, if that process starts, are we
Speaker 6: more or less complex than that typical process? And I
Speaker 6: think we don't know the answer to that obviously, but
Speaker 6: I think what I can say is from the sort
Speaker 6: of structure of the physical laws in the theory that
Speaker 6: we're building and testing, every evolutionary system will have to
Speaker 6: climb the ladder of complexity, so there is no major
Speaker 6: jump where you just get to be like the most
Speaker 6: complex thing in the universe by skipping steps. So that
Speaker 6: becomes a question of did life start in the universe
Speaker 6: on any planets much before us or have an accelerated
Speaker 6: process moving through the sort of complexity cascade. And I
Speaker 6: don't think anyone knows the answer to that question. That's
Speaker 6: one of the reasons that we want to understand this
Speaker 6: physics so we can actually make predictions about what that
Speaker 6: process looks like on other planets. And I think we're
Speaker 6: at this stage where I'm hopeful, you know, in the
Speaker 6: next I don't know, ten years, maybe we might be
Speaker 6: able to say something meaningful about the first steps from
Speaker 6: geochemistry using this kind of theoretical construction like these kind
Speaker 6: of steps about like what are the first mechanisms of
Speaker 6: selection that emerge in chemistry and what do they look
Speaker 6: like in different planetary contexts. But saying something about that
Speaker 6: whole cascade is basically simulating the entire evolutionary process, you know,
Speaker 6: from the geochemical original life into technology on another planet.
Speaker 6: And I don't think that's actually computationally feasible. I think
Speaker 6: we have to discover other life to answer that question,
Speaker 6: which is why we need a theory to know what
Speaker 6: we're looking for.
Speaker 5: So would geologists come across molecules that look complicated or
Speaker 5: in chemistry? Was the class I did not get?
Speaker 3: As in, yeah, so how do you know that you've got.
Speaker 5: Like a complicated molecule that's life or do you get
Speaker 5: similarly complicated molecules in a geology lab that.
Speaker 3: Are not alive.
Speaker 6: It's a non trivial question, highly non trivial, and I
Speaker 6: think part of it comes from the different uses of
Speaker 6: the word complexity. So I think a lot of my
Speaker 6: planetary science colleagues and geologist would say, of course we
Speaker 6: find complexity in chemical systems.
Speaker 8: We see it all the time.
Speaker 6: The kind of complexity that they're talking about is often
Speaker 6: what we see in prevotic chemistry experiments also, which is
Speaker 6: oftentimes like the most problematic thing you see in prevatic chemistries.
Speaker 6: If you just run an unconstrained reaction, you get what
Speaker 6: we call a tar, which is a non differentiated mess
Speaker 6: of molecules. So these kind of systems can generate a
Speaker 6: lot of molecular diversity, but it tends to be things
Speaker 6: that would be low complexity as individual molecules, and for
Speaker 6: things that are higher complexity, you don't see a lot
Speaker 6: of them. And that's very different than what we see
Speaker 6: in life, which is we see, you know, there's a
Speaker 6: lot of diversity and molecules in life, but compared to
Speaker 6: the size of the chemical space that that could be
Speaker 6: you know, equivalent structure like molecule or way, or you know,
Speaker 6: number of chiral centers or you know, number of elements
Speaker 6: in the molecule, like any of these features you might
Speaker 6: say is equivalent molecules. You see very very very very
Speaker 6: low diversity in biology. And so what biology does is
Speaker 6: it builds molecules that are deep in the space of chemistry,
Speaker 6: like they require a lot of parts to build the
Speaker 6: specific molecule, so that molecule is complex in an evolutionary sense,
Speaker 6: it's found in high abundance, but there's not a huge
Speaker 6: diversity of exploring in an unconstrained way the space of
Speaker 6: all molecules. So I think the kind of complexity we
Speaker 6: talk about in a planetary science sense doesn't discover the
Speaker 6: kind of complexity that biology generates.
Speaker 1: So let's dig into that a little bit, because I
Speaker 1: think that's really at the core of the argument in
Speaker 1: your book, right, this concept of complexity and how we
Speaker 1: discover it and what it means for life to be complex.
Speaker 1: So you're saying that life is something that uses a
Speaker 1: relatively small number of building blocks but puts them together
Speaker 1: in a way that's very complex. Right. The complexity comes
Speaker 1: from the arrangements of a few bits, not from the
Speaker 1: inherent complexity of the pieces, and that we of the
Speaker 1: chemical space that exists out there. As you're saying earlier,
Speaker 1: it uses a tiny, little, very tiny, yeah, very tiny,
Speaker 1: little aspect of that. And so again I wonder, like,
Speaker 1: how do we know how unusual that is, or how
Speaker 1: special that is, how distinct that is? How do we
Speaker 1: know that it's not possible using other building blocks to
Speaker 1: create complexity? How do we know that complexity doesn't always
Speaker 1: arise if you start from you know, basic bits.
Speaker 6: Yeah, this is the more exciting question, and it's actually,
Speaker 6: you know, the one experimentally, I'm really interested in. If
Speaker 6: you designed an original life experiment that was modeling a
Speaker 6: planetary environment and it was unconstrained and selection and evolutionary
Speaker 6: processes emerged in the system just by the dynamics of
Speaker 6: the chemistry, would it discover the same biochemistry?
Speaker 8: And I'm not convinced it would.
Speaker 6: I think space is so large that there are a
Speaker 6: lot of potential chemical architectures for life that could be
Speaker 6: quite different, but we haven't discovered them yet. Because life
Speaker 6: on Earth, you know, had one solution that allowed it
Speaker 6: to perpetuate itself and had to use that architecture for
Speaker 6: billions of years. And you know, the question is if
Speaker 6: the original life happened again, would it discover the same
Speaker 6: architecture or not?
Speaker 8: And nobody knows the answer to that.
Speaker 6: I think that's an experimental question, you know, and that's
Speaker 6: one that we want to ask because you know, part
Speaker 6: of the thing I you know, try to really highlight
Speaker 6: in the discussion in the book, but I'm also really
Speaker 6: trying to just pitch to people as an experimental program
Speaker 6: that we need to do because it requires a lot
Speaker 6: of investment of technology and resources, is to think through
Speaker 6: how we would build an experimental program to discover alien life.
Speaker 8: In the lab and the idea of Eric exactly in
Speaker 8: the lab.
Speaker 6: Yes, it's exactly what you're saying though, like we don't
Speaker 6: know if life could exist in other chemistries. If you
Speaker 6: do a proper original life experiment and you really want
Speaker 6: to know the spontaneous probability for a universe to generate life,
Speaker 6: you can't just cherry pick and use them like our
Speaker 6: structures that were selected on Earth and say I'm going
Speaker 6: to make these because you're inducing selection based on what
Speaker 6: was produced on Earth right prior knowledge of it. You
Speaker 6: really want to see from chemistry what would it generate
Speaker 6: without any intervention from us, as you know, designers of
Speaker 6: the chemistry, knowing what we know of Earth life. So
Speaker 6: I think the original life problem is actually that's exactly
Speaker 6: what it is, is an experimental problem to try to
Speaker 6: discover what is the mechanism chemistry generates living forms. And
Speaker 6: if you know that mechanism, is it universally going to
Speaker 6: converge on what life on Earth did? Or are there
Speaker 6: many solutions because this space is so huge.
Speaker 3: I'm sure you could get a lot of evolutionary biologies
Speaker 3: very excited if you could repeatedly generate them.
Speaker 8: You need their talent, so that's good. Yeah, I think
Speaker 8: you know.
Speaker 6: Part of my motivation with right, it's hard to write
Speaker 6: a book, right, And for first and foremost, I'm about
Speaker 6: this science, like I just really want to solve the
Speaker 6: original life. So part of my motivation is to get
Speaker 6: people excited about like what are the actual critical challenges here?
Speaker 6: And I think this one is like the main one
Speaker 6: is like what does the experimental program look like that
Speaker 6: solves the original life? And how related is it to
Speaker 6: all these other questions that we're talking about. And for me,
Speaker 6: it is going to require you know, really intense technological infrastructure,
Speaker 6: building digital chemistry and AI driven robotic chemistry to actually
Speaker 6: search chemical space like a search engine, and then looking
Speaker 6: for these kind of chemistries and when they undergo selection
Speaker 6: and they start emerging things that we might call life.
Speaker 6: And the reason for having to build a theory in
Speaker 6: part besides all the reasons I have as a physicist,
Speaker 6: is if the chemistry is radically different, how do you
Speaker 6: even know it's a living thing, and so we have
Speaker 6: to be able to measure evolution in molecules agnostic to
Speaker 6: what molecules evolution creates, and know that they have a
Speaker 6: comparable level of selection in them to say that, you know,
Speaker 6: this is past the threshold that we expect it to
Speaker 6: be a live form versus you know what, we expect
Speaker 6: a big systems that aren't evolving to be able to generate.
Speaker 1: And so this is sort of the core argument of
Speaker 1: your book. You describe assembly theory, where you measure the
Speaker 1: complexity of something as the number of steps it takes
Speaker 1: essentially to build some of the shortest path to go
Speaker 1: from building blocks to this thing, right, and then you
Speaker 1: do this thing where you say, well, anything above fifteen
Speaker 1: steps is life, and anything below fifteen steps is not life.
Speaker 1: And I was with you until I got to that point.
Speaker 1: I found myself asking, as you actually did in the book,
Speaker 1: like well, why fifteen doesn't it feel sort of arbitrary?
Speaker 1: How do we know it's fifteen?
Speaker 8: It's like it should be forty two, right, forty two
Speaker 8: would have been better?
Speaker 1: Yeah, gives a description of that thought process.
Speaker 8: No, it's a good question.
Speaker 6: So fifteen is maybe an approximate bound, right, But where
Speaker 6: that comes from is actually the experimental data. So it's
Speaker 6: not like anointed, you know, like the assembly theory cult
Speaker 6: said it's going to be fifteen.
Speaker 8: It's just like, you know, we build it.
Speaker 1: How do I do any cult?
Speaker 4: I know?
Speaker 1: Right?
Speaker 6: And there is no cult actually, Like it's really funny
Speaker 6: because you know, there's a lot of challenges we're getting
Speaker 6: developing this theory from people picking it apart different ways,
Speaker 6: which we love, but I don't think anyone's harder on
Speaker 6: it than the people we have actually working on it.
Speaker 8: So it's like, which is the best kind of science?
Speaker 6: Right, Like you pick apart every idea and you re
Speaker 6: evaluate everything you're doing at every step.
Speaker 1: Well, if you're denying the existence of the cult, that
Speaker 1: tells me that the cult definitely exists.
Speaker 8: Oh sure, yeah, I know right, you're just I'm going
Speaker 8: to wink link wink.
Speaker 1: Tell us about the data that supports the choices.
Speaker 8: Yeah, so that comes from the data.
Speaker 6: So this idea of this minimal past, so it involves
Speaker 6: you recursions. So the idea is like it's easier with
Speaker 6: lego than chemistry, you know, because most of us aren't chemists.
Speaker 6: So it's like you think you're building a particular lego structure.
Speaker 6: I usually use Howkwarts castle with people know, but like
Speaker 6: the taj Ma hall or whatever you know, building you
Speaker 6: might prefer, you know, you wouldn't expect to form it
Speaker 6: by randomly shaking the building blocks in the box.
Speaker 8: Right, there's instructions that allow you to make it. In
Speaker 8: assembly theory, you realize.
Speaker 6: If you take the instructions, there's actually lots of different
Speaker 6: ways of getting to the end if you don't use
Speaker 6: the instructions. Right, So in assembly theory we have to
Speaker 6: ground it in something that's always there about that structure,
Speaker 6: and not just because you had a particular set of
Speaker 6: instructions in a particular environment to make that. And so
Speaker 6: we do this based on this minimal path idea. And
Speaker 6: the assumptions of the minimal path are you can only
Speaker 6: build things if you already build them, and you want
Speaker 6: to try to find the shortest path where you're reusing
Speaker 6: parts you've built already to build the final structure.
Speaker 8: So very minimal set of assumptions.
Speaker 6: It turns out that feature you can actually measure in
Speaker 6: the lab, and we measured it in the paper that
Speaker 6: we tried to do biosignature validation in using mass spectrometry,
Speaker 6: But there was a later paper from Leekronin's group that
Speaker 6: came out showing that you can also measure assembly index
Speaker 6: this shortest path measure with NMR and infrared.
Speaker 8: So we have a strong sort of.
Speaker 6: Conviction right now as a RUNN assumption with a theory
Speaker 6: that it's an intrinsic property of a molecule, this feature,
Speaker 6: it's one that you can measure with independent measuring apparatus.
Speaker 6: It doesn't depend on where the environment where the molecule
Speaker 6: was made. That gives us some of the baseline criteria
Speaker 6: of something being an objective measure of the amount of
Speaker 6: selection in an object. And then what you have in
Speaker 6: a molecule that you can go and measure in the lab.
Speaker 6: So you know, if I went to Enceladus and I
Speaker 6: measured it, you know the molecule would have the same
Speaker 6: value it would have on Earth.
Speaker 8: Okay, so that's important. And so the question is then
Speaker 8: if you use.
Speaker 6: That, does it actually separate out things that are uniquely
Speaker 6: produced by life from not? And so to do this,
Speaker 6: Lee's lab took a bunch of samples, you know, abiotic
Speaker 6: and biotic, even some Scotch whiskey, and then they had
Speaker 6: some samples that were blinded from NASA that were both
Speaker 6: biological and non biological, sort of an adversarial test case.
Speaker 6: And what they did is they use this mass spect
Speaker 6: method to measure assembly index on the actual samples, and
Speaker 6: they showed that using assembly theory combined with the mass
Speaker 6: spect data, they only saw molecules that were more than
Speaker 6: fifteen steps in this minimal path being produced by living samples.
Speaker 6: And this gets to the complicated versus complexity issue because
Speaker 6: one of the adversarial samples that NASA cent was actually
Speaker 6: Murchison meteorite, which oftentimes in prebatic chemistry literature you will
Speaker 6: see as being like the most complex sample of prebatic chemistry,
Speaker 6: and it was still below fifteen for the molecules in
Speaker 6: the sample. So what you see Murchison is again this tar.
Speaker 6: You have a lot of molecules, but none of them
Speaker 6: are high abundance and a high assembly. And so it's
Speaker 6: not just that the molecule is high assembly. You actually
Speaker 6: have to have it in a high enough abundance to
Speaker 6: say that it was selected in that particular context.
Speaker 1: Right, So, but does that mean that if I find
Speaker 1: some sample on an alien planet and you measure its
Speaker 1: assembly index and it comes out to forty two, You're
Speaker 1: going to be like, this is life? Are you proposing
Speaker 1: this as a definition of life? A discrow way to decide?
Speaker 6: I think that would be the ultimate outcome based on
Speaker 6: the path that we're on, but I think we have
Speaker 6: a lot more work to do to be like definitively
Speaker 6: there is a threshold and assembly spaces above which you
Speaker 6: would say that a sample was life or not.
Speaker 8: And that's sort of where we're going.
Speaker 6: So right now, I would be pretty high confident if
Speaker 6: you discovered something on Enceladus that was forty two that
Speaker 6: it could only be produced by life. But the sort
Speaker 6: of next steps are really actually theoretically predicting why it
Speaker 6: should be the number fifteen and what number it should
Speaker 6: be if you have variations in your elemental distributions or
Speaker 6: other things about the structure of the assembly space, which
Speaker 6: is the underlying mathematical structure that we build this.
Speaker 8: Whole formalism out of.
Speaker 6: And so one of the projects in my lab right
Speaker 6: now is actually trying to quantify why there's a transition
Speaker 6: in assembly theory at the particular assembly index values that
Speaker 6: we see and might see in different systems.
Speaker 1: Because as you say, the chemical space is very large
Speaker 1: and petible, that there's structures out there that are quite
Speaker 1: complex but that nobody would call alive.
Speaker 6: Right, So there are many such structures, right, So it's
Speaker 6: not necessarily that the threshold must be at fifteen.
Speaker 8: That's where we.
Speaker 6: Have for the kinds of chemistry that we test in
Speaker 6: labs so far. When we have a general theory, which
Speaker 6: we're working on very fervently right now with our teams,
Speaker 6: we would be able to predict, based on the sort
Speaker 6: of elemental composition and other features of your chemistry, where
Speaker 6: that threshold should be. And then that allows us further
Speaker 6: tests to really validate that this works in different systems.
Speaker 6: And you know, one place where it might be more
Speaker 6: challenging is actually with minerals because minerals don't uphold all
Speaker 6: of the properties of molecules. They have very different structure,
Speaker 6: but they're also made out of elements bonding and minerals
Speaker 6: because they have very different structure to how you build
Speaker 6: up a mineral in this kind of way that we do,
Speaker 6: this kind of recursive construction and what you would define
Speaker 6: as a repeat in a mineral, they might have a
Speaker 6: you know, a threshold that's much higher than what we
Speaker 6: observe for aqueous molect our chemistry. And so, as with
Speaker 6: any new theory of physics, it's a process of suggesting
Speaker 6: an idea, testing it, iterating on the idea. And so
Speaker 6: you know, the process of theory building doesn't happen overnight.
Speaker 6: It happens over a decade or two. And so these
Speaker 6: are some of the frontier questions that we're asking about, Like,
Speaker 6: you know, is this actually you know the right approach,
Speaker 6: then these things should work out, but we don't know
Speaker 6: the answer yet.
Speaker 8: So that's why it's exciting.
Speaker 5: Sometimes life gets overwhelming, and sometimes conversations about life get overwhelming.
Speaker 5: So I feel like it's time for a break. So
Speaker 5: let's go ahead and hear a word from our sponsors.
Speaker 1: When you pop a piece of cheese into your mouth
Speaker 1: or enjoy a rich spoonful of Greek yogurt, you're probably
Speaker 1: not thinking about the environmental impact of each and every bite.
Speaker 1: But the people in the dairy industry are us. Dairy
Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse
Speaker 1: gas neutral by twenty to fifty. That's why they're working
Speaker 1: hard every day to find new ways to reduce waste
Speaker 1: conserve natural resources and drive down greenhouse gas emissions. Take water,
Speaker 1: for example, most dairy farms reuse water up to four
Speaker 1: times the same water cool the milk, cleans equipment, washes
Speaker 1: the barn, and irrigates the crops. How is US dairy
Speaker 1: tackling greenhouse gases? Many farms use anaerobic digestors that turn
Speaker 1: the methane from maneuver into renewable energy that can power farms, towns,
Speaker 1: and electric cars. So the next time you grab a
Speaker 1: slice of pizza or lick an ice cream cone, know
Speaker 1: that dairy farmers and processors around the country are using
Speaker 1: the latest practices and innovations to provide the nutrient deents
Speaker 1: dairy products we love with less of an impact. Visit
Speaker 1: us dairy dot com slash sustainability to learn more.
Speaker 10: There are chiltern friends and families walking, riding on passing
Speaker 10: the roads every day. Remember they're real people with loved
Speaker 10: ones who need them to get home safely. Protect our
Speaker 10: cyclists and pedestrians because they're people too. Go safely California
Speaker 10: from the California Office of Traffic Safety and Caltrans Hey.
Speaker 11: Their fellow globetrotters and destination dreamers. If you're anything like us,
Speaker 11: you'd note that life's too short for boring toasters and towels.
Speaker 11: That's why we decided to ditch the traditional wedding registry
Speaker 11: and went with honeyfund dot Com. Imagine your friends and
Speaker 11: family chipping in to send you on a dreamy, exotic honeymoon.
Speaker 11: Practical check, meaningful, double check. Plus, it's fee free and
Speaker 11: so fun for wedding guests to shop. So why get
Speaker 11: more stuff when you can have unforgettable experiences. Join the
Speaker 11: revolution at honey fund dot com and start your adventure today.
Speaker 7: Whether you like fresh faced, full glam, or somewhere in between,
Speaker 7: you've probably seen Thrive Cosmetics viral tubing mescara, you know,
Speaker 7: the one in the turquoise tube all over your socials.
Speaker 7: It's easy to see why their bestsellers have thousands of
Speaker 7: five star reviews. I love their high performance formulas. The
Speaker 7: Brilliant Eye Brightener is one of my faves, and I
Speaker 7: love it because it's so versatile. You can use it
Speaker 7: as a highlighter or an eyeshadow. It's amazing. Refresh your
Speaker 7: everyday look with Thrive Cosmetics, Beauty that gives back. Right now,
Speaker 7: you can get an exclusive twenty percent off your first
Speaker 7: order at Thrivecosmetics dot com slash nine O two one zero.
Speaker 7: That's Thrive Cosmetics. A you s E M E Tics
Speaker 7: dot com slash nine O two and oh, we're twenty
Speaker 7: percent off your first order.
Speaker 1: I hope your brains are arrested and ready for some
Speaker 1: more overwhelming conversation about incredible topics like the physics of life.
Speaker 1: It is exciting. One question I would have in my
Speaker 1: mind if I was working on this is like, whether
Speaker 1: the value is fifteen or nineteen or fourteen or whatever,
Speaker 1: how do we know that all the information is captured
Speaker 1: by this one quantity. You back it up so far
Speaker 1: with like, well, we have a bunch of these examples,
Speaker 1: then it seems to have worked, and you're working on
Speaker 1: the theoretical underpinnings.
Speaker 11: You know.
Speaker 1: I work on machine learning problems all the time where
Speaker 1: we convince ourselves we've learned how to distinguish between A
Speaker 1: and B because we've only seen some kind of examples,
Speaker 1: and then we go off into the world where like, oops,
Speaker 1: turns out that's just one dimension of a multidimensional problem.
Speaker 1: You know, for example, if I was not intelligent about
Speaker 1: this and I said, well, look I took a bunch
Speaker 1: of examples of living things that all have brown hair
Speaker 1: and non living things that don't have brown hair, and
Speaker 1: then I developed my definition of life to be like,
Speaker 1: does it have brown hair? I could also come up
Speaker 1: with a way to distinguish between quote unquote living and
Speaker 1: unliving things because my sample was limited, and here your
Speaker 1: sample is limited because you only have examples from you know,
Speaker 1: life we've seen and so how do I know that
Speaker 1: there is a number that distinguishes.
Speaker 8: So there's a couple of things there.
Speaker 6: One of them is assembly theory is not a scaler theory,
Speaker 6: so it's not just about this number. It's actually about
Speaker 6: also the abundance of objects at different assembly indites.
Speaker 8: So it's higher dimensional than that.
Speaker 6: And the idea is you're talking about selection in this
Speaker 6: massive combinatorial space, and you have to talk about the
Speaker 6: reduction of the size of the space represented in the
Speaker 6: objects you observe. And we have rigorous ways for thinking,
Speaker 6: like based on the mathematical formalism of the theory, why
Speaker 6: we're capturing the relevant features of that reduction of.
Speaker 8: The size of the space.
Speaker 6: People usually do do exactly what you're saying, where they
Speaker 6: try to, you know, separate living and non living things
Speaker 6: and then classify them. And it's becoming very popular in
Speaker 6: natro biology right now to do machine learning on those
Speaker 6: kind of problems. I don't think that that approach is generalizable.
Speaker 6: The reason I have confidence in what we're doing is
Speaker 6: because there's a whole theoretical infrastructure building in a whole
Speaker 6: bunch of ideas about the nature of information in life,
Speaker 6: what is causation in life?
Speaker 8: How do we measure these features in molecules? You know?
Speaker 6: What is it about these emergent properties of life? Like
Speaker 6: you know, I've spent my entire career basically working on
Speaker 6: every kind of biological system imaginable, and you know, Lee's
Speaker 6: lab has worked on kind of every chemical system imaginable,
Speaker 6: and putting all of that knowledge into one theoretical structure
Speaker 6: that we can really stand behind and say, this captures
Speaker 6: the features we think are important, and we can measure it,
Speaker 6: and we want to test it by actually building living
Speaker 6: things in the lab. So it's not ever going to
Speaker 6: be convinced by just this measure and the copy number.
Speaker 6: What you get convinced of is an explanatory paradigm that
Speaker 6: allows you to explain not just this one data set,
Speaker 6: but a whole bunch of different things, And so ultimately
Speaker 6: the proof of the theory is going to come from
Speaker 6: the generalizability and the new questions it allows us to answer.
Speaker 6: Not what we've done so far, so't I wouldn't hang
Speaker 6: my hat on it the data we have so far.
Speaker 6: But what I'm hanging my hat on is the potential
Speaker 6: things that this is opening up and the way it's
Speaker 6: allowing a unified explanation for a whole bunch of problems
Speaker 6: in astrobiology that have traditionally been considered completely separate. And
Speaker 6: also on what we talked about at the very beginning
Speaker 6: about what is physics and what does physics do? And
Speaker 6: for me, it's about the explanation for the nature of
Speaker 6: life that's more important than anyone experiment.
Speaker 3: That feels like a nice note to end things on,
Speaker 3: like a nice wrap up is did you have another question, Daniel.
Speaker 1: Yeah, I would love to hear just as a final vision,
Speaker 1: like how you think this could, in the best case
Speaker 1: scenario come together like you talk in the book about
Speaker 1: building these computers, how you search for the origin of
Speaker 1: life and when I do science, I was trying to imagine,
Speaker 1: like what's the fantasy data I would have, Are you
Speaker 1: hoping that we discover like alien life here on Earth
Speaker 1: before we discover it on Enzi? Let us would actually
Speaker 1: be your preference? Take us through your scientific fantasy, right.
Speaker 6: So my preference is that we just discover more life
Speaker 6: and we understand what life is. So my preference is
Speaker 6: understand what life is and have enough scientific evidence to
Speaker 6: support that explanation. The progress of science is that's never
Speaker 6: a single aha moment. It's like, you know, a cultural transformation,
Speaker 6: and the way we understand a certain set of phenomena
Speaker 6: mediated by a whole bunch of experiments and observations and
Speaker 6: a consilience of like a whole bunch of things coming together. Right,
Speaker 6: So I think that process is highly nonlinear. For me,
Speaker 6: the reason I really advocated more for this experimental approach
Speaker 6: in the lab is the idea that you could iterate
Speaker 6: between the observation and theory very quickly. So the challenge
Speaker 6: for looking for life on alien worlds is we don't
Speaker 6: know the prior probability for life, and we don't know
Speaker 6: what we're looking for, and so we don't know how
Speaker 6: many planets we have to survey before we find something.
Speaker 6: And nor is it the case that we can actually
Speaker 6: rule out a planet is alive or not. And so
Speaker 6: I think by trying to bring the paradigm of looking
Speaker 6: for alien life into an experimental paradigm, and when we
Speaker 6: were actually building large enough chemical search engines to look
Speaker 6: for alien life, we actually make it tractable to understand
Speaker 6: the mechanism of the original life, the probability it doesn't happen,
Speaker 6: and also build the theory and experiments to really test
Speaker 6: how it does happen at the same time. So to me,
Speaker 6: it seems the most efficient route to get actually getting
Speaker 6: to the answer to the question. And so and you know,
Speaker 6: part of it might be biased by my background in
Speaker 6: cosmology and just looking at the way that particle physicists
Speaker 6: and cosmology have collaborated to really like, you know, why
Speaker 6: do we understand the mechanisms of like the Big Bang
Speaker 6: so well, it's.
Speaker 8: Because we build particle accelerators.
Speaker 6: And so I think without an experimental paradigm for these
Speaker 6: questions that really ties the planetary and the alien search
Speaker 6: to the original life, you have to couple those problems
Speaker 6: through the same problem at their core. And I also
Speaker 6: just like the radical idea that like alien life will
Speaker 6: discover it on Earth and an experiment.
Speaker 8: Because it's fine, but then we'll know what we're looking for.
Speaker 6: So it was more obvious we can find it elsewhere, right, So,
Speaker 6: like to me, that just seems logical, but it's also
Speaker 6: fun because you know, like, it means we can do
Speaker 6: the science really rapidly, and I want to see it solved,
Speaker 6: so I want the most efficient route to an answer.
Speaker 1: And then we'll have to argue about whether it's really
Speaker 1: alien if it was on Earth after all.
Speaker 6: Right, that's a good problem to have, right, because yeah,
Speaker 6: a really good problem to.
Speaker 3: Have come full circle to good beer conversations.
Speaker 8: Yes, yes, there you go.
Speaker 6: See if you answer one of the beer questions, but
Speaker 6: you have a better beer question, it's not a problem.
Speaker 3: Yep.
Speaker 1: Well, thank you very much for coming on and talk
Speaker 1: to us about assembly theory and for giving us an
Speaker 1: advanced peak at your book. Everyone, it's called Life As
Speaker 1: No One Knows It, the physics of Life's emergence. Congratulations
Speaker 1: on the book and best of luck.
Speaker 8: Thank you so much, Thank you both.
Speaker 3: Yeah, thank you.
Speaker 1: All right, and that was our conversation with Sarah and
Speaker 1: Maria Walker, author of the recent book Life As No
Speaker 1: One Knows it, which you can now pick up at
Speaker 1: all fine booksellers. Kelly, what's your takeaway is physics is
Speaker 1: going to help us understand what life is.
Speaker 5: Well, you know, my takeaway is pretty similar to my
Speaker 5: takeaway many years ago when I was arguing with my
Speaker 5: fellow grad students, which is, Wow, this is complicated, which
Speaker 5: is pretty much the conclusion to every ecology paper you'll
Speaker 5: ever read is it's complicated and it depends and anyway.
Speaker 5: So yeah, it's complicated.
Speaker 3: What do you think.
Speaker 1: I think it's a valiant effort and it's worth doing,
Speaker 1: and we're going to learn things along the way. I
Speaker 1: don't know that we're going to figure it out. I
Speaker 1: don't know that this is the right approach, but I
Speaker 1: think thinking hard about it is the first step to
Speaker 1: figuring it out. No matter where it goes. Often you
Speaker 1: go down to the root of something and you discover
Speaker 1: something completely different than solving the problem you meant to,
Speaker 1: or you make breakthroughs in other areas. So I'm excited
Speaker 1: to see where this goes. I'm excited that people are
Speaker 1: thinking about these problems. I think it helps clear away
Speaker 1: some of the cobwebs and provides a little bit of clarity,
Speaker 1: But I guess I have to put it into like
Speaker 1: we'll see category before I'm actually convinced that this is
Speaker 1: the right way to think about life.
Speaker 5: I mean, it would be pretty epic if like on demand,
Speaker 5: new life could be created in the lab and we
Speaker 5: could look at different evolutionary trajectories and stuff like that.
Speaker 5: I mean, the evolutionary biologists would go wild if that.
Speaker 3: Could be accomplished.
Speaker 5: I don't know where you start to do something like that,
Speaker 5: but it would be pretty exciting if it could be accomplished.
Speaker 1: Yeah. And then, of course, the next philosophical question would
Speaker 1: be if you've created a new kind of living goo
Speaker 1: in your lab, is it an alien or is it
Speaker 1: just another kind of earthling?
Speaker 3: And how long before it begins to eat human flesh?
Speaker 1: Day one? I'm hoping. I mean, if this movie's going
Speaker 1: to be any good, right, yeah.
Speaker 3: No, it's going to happen fast.
Speaker 8: Yeah.
Speaker 1: I mean you could also flip the question around and
Speaker 1: like say that new kind of living goo becomes intelligent,
Speaker 1: how do we know it doesn't call us aliens?
Speaker 6: Right?
Speaker 1: And like we're at home, how can we be aliens?
Speaker 5: That's right, that's right, let's all just get along and
Speaker 5: be Earthlakes.
Speaker 8: Am I right?
Speaker 1: That sounds good exactly. I look forward to a big,
Speaker 1: cozy family meal, passing the bread and the corn cobs
Speaker 1: around with our fellow Earth new.
Speaker 5: I'm going to schedule it one week after our meeting
Speaker 5: where you tell me about how physics have solved all
Speaker 5: the problems.
Speaker 4: Of the world.
Speaker 1: Sounds good, and I'll bring some towels.
Speaker 3: That's good because I'll forget mine.
Speaker 1: Bring extra, please, Katriina, We'll have an extra win in
Speaker 1: her bag. No worries, all right. Thanks everyone for joining
Speaker 1: us on this squishy discussion about the physics of life.
Speaker 1: Hope you learned something I certainly did. And thank you
Speaker 1: very much Kelly, my friend and co host, for joining
Speaker 1: me on today's episode.
Speaker 3: My pleasure. Thanks Daniel.
Speaker 1: Tune in next time for more science and curiosity. Come
Speaker 1: find us on social media where we answer questions and
Speaker 1: post videos. We're on Twitter, Discorg, Instant, and now TikTok.
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts
Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
Speaker 1: you listen to your favorite shows. When you pop a
Speaker 1: piece of cheese into your mouth, you're probably not thinking
Speaker 1: about the environmental impact. But the people in the dairy
Speaker 1: industry are. That's why they're working hard every day to
Speaker 1: find new ways to reduce waste, conserve natural resources, and
Speaker 1: drive down greenhouse gas emissions. How is us dairy tackling
Speaker 1: greenhouse gases? Many farms use anaerobic digestors to turn the
Speaker 1: methane from manure into renewable energy that can power farms, towns,
Speaker 1: and electric cars. Visit you as dairy dot COM's Last
Speaker 1: Sustainability to learn more.
Speaker 4: As a United Explorer Card member, you can earn fifty
Speaker 4: thousand bonus miles plus look forward to extraordinary travel rewards,
Speaker 4: including a free checked bag, two times the miles on
Speaker 4: United purchases and two times the miles on dining and
Speaker 4: at hotels. Become an Explorer and seek out unforgettable places
Speaker 4: while enjoying rewards everywhere you travel. Cards issued by JP
Speaker 4: Morgan Chase Bank NA Member FDIC subject to credit approval offer,
Speaker 4: subject to change. Terms apply.
Speaker 7: I'm a cleaning lady, a single mine with three kids
Speaker 7: and an IQ north of one sixty, so helping the
Speaker 7: cops solve a murder.
Speaker 3: It's literally the easiest part of my day.
Speaker 12: ABC Tuesday the series premiere of falls most anticipated new
Speaker 12: drama High Potential.
Speaker 6: That big brain of hers is going to help us
Speaker 6: close out a lot of cases.
Speaker 12: Caitlin Olfin is a new face of investigation.
Speaker 8: You're a single mom pretending to be a god.
Speaker 1: I am not pretending.
Speaker 3: I'm just out here super copping.
Speaker 12: High Potential series premiere Tuesday, ten ninth Central on ABC
Speaker 12: and stream on Hulu.