Latest / Daniel and Kelly’s Extraordinary Universe / What is the Physics of life?

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What is the Physics of life? · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: Daniel, it's good to see you. I have a question
• 0:09
  Speaker 1: that I have been dying to ask you. When is
• 0:12
  Speaker 1: physics going to unravel the deep mysteries of the universe?
• 0:15
  Speaker 2: Wow? Right into it? Huh. Unfortunately, we don't have that
• 0:19
  Speaker 2: on our schedule exactly, and it's going to be as
• 0:22
  Speaker 2: long as it takes.
• 0:23
  Speaker 3: You know what.
• 0:24
  Speaker 1: I need to do something important, but I keep putting
• 0:26
  Speaker 1: it off. I put it on a calendar and give
• 0:28
  Speaker 1: myself a deadline. I find that that actually makes it happen,
• 0:31
  Speaker 1: So you should schedule it.
• 0:33
  Speaker 2: All right, let's do it. I'm putting on my calendar.
• 0:35
  Speaker 2: Let's have a zoom meeting to share our ultimate enlightenment
• 0:38
  Speaker 2: about the universe. Have about June twenty twenty nine. That
• 0:41
  Speaker 2: work for you?
• 0:42
  Speaker 3: Uh?
• 0:42
  Speaker 1: You know, I feel like when you come up with
• 0:44
  Speaker 1: budgets and timelines, you always need to multiply by at
• 0:47
  Speaker 1: least three. So let's do something in the twenty forties
• 0:50
  Speaker 1: and I think you'll have.
• 0:52
  Speaker 3: Enough time then. So there it's scheduled. And that was easy.
• 0:56
  Speaker 2: Yeah. Well, you know now I'm worried that scheduling our
• 0:59
  Speaker 2: ultimate enlightened is going to lead us right into the
• 1:02
  Speaker 2: Hitchhiker's Guide to the universe.
• 1:03
  Speaker 3: Trap like I'm gonna forget my towel.
• 1:06
  Speaker 2: That maybe, but more importantly, we might get the answer
• 1:10
  Speaker 2: and have no idea what the question was.
• 1:14
  Speaker 4: Yep, yep, that's a tough one.
• 1:31
  Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor
• 1:34
  Speaker 2: at U c Irvine, and I never forget my towel.
• 1:37
  Speaker 1: I'm Kelly Wiersmith, and my kids are always annoyed with
• 1:40
  Speaker 1: me because I'm the only mom at the pool who
• 1:42
  Speaker 1: always forgets the towels. And I'm a junct faculty at
• 1:45
  Speaker 1: Race University.
• 1:46
  Speaker 2: How can you be forgetting towels? I mean, you have
• 1:48
  Speaker 2: these young kids, they're always making messes. I mean everybody's kids,
• 1:51
  Speaker 2: not yours a particular. You gotta just learn to bring
• 1:53
  Speaker 2: the towel wherever you go.
• 1:54
  Speaker 1: Right, I am resistant to learning. I guess I should
• 1:59
  Speaker 1: know by now, but I never All the other moms
• 2:01
  Speaker 1: have the big bags and they got snacks and goldfish.
• 2:03
  Speaker 3: My kids are always like, where are the goldfish?
• 2:06
  Speaker 1: Everybody else has goldfish, and I'm like, tell it to
• 2:09
  Speaker 1: your shrinking a couple of.
• 2:10
  Speaker 3: Years, kid, I'm sorry.
• 2:11
  Speaker 2: At least I have something to complain about, right. My
• 2:14
  Speaker 2: wife has one of those big bags, but she doesn't
• 2:16
  Speaker 2: just have snacks and goldfish in it. She's got all
• 2:19
  Speaker 2: sorts of random crap in there. And my kids are
• 2:21
  Speaker 2: always making fun of her for it until the moment
• 2:24
  Speaker 2: where they're like, hey, mom, wait, do you have chapstick
• 2:27
  Speaker 2: or do you have a spoon, And she's like, of
• 2:29
  Speaker 2: course I do, and she digs it out of a
• 2:31
  Speaker 2: bag and then she's like the savior.
• 2:33
  Speaker 3: Mom to the rescue.
• 2:37
  Speaker 2: Moms are the best, absolutely and so Welcome to the
• 2:40
  Speaker 2: podcast that celebrates moms but also asks the deepest questions
• 2:45
  Speaker 2: in the universe. We want to know how everything works,
• 2:48
  Speaker 2: where it all came from, how it all can possibly
• 2:50
  Speaker 2: make sense to our squishy little brains. Welcome to Daniel
• 2:54
  Speaker 2: and Jorge Explain the Universe, a production of iHeartRadio.
• 2:59
  Speaker 1: So today we're going to be talking about a topic
• 3:00
  Speaker 1: that's near and dear to my heart. I've spent many
• 3:02
  Speaker 1: hours arguing over this question with friends, but I'll let
• 3:06
  Speaker 1: you go ahead and introduce it. I'm just just wanted
• 3:08
  Speaker 1: to preface that I'm excited.
• 3:11
  Speaker 2: On this podcast. We talk about some of the deepest
• 3:13
  Speaker 2: questions in the universe. How is everything made, where it
• 3:16
  Speaker 2: all come from what are the tiny little quantum particles?
• 3:18
  Speaker 2: How do they weave themselves together in order to explain
• 3:21
  Speaker 2: this existence? And where possibly did we leave our towels?
• 3:25
  Speaker 2: But today in the podcast, we're going to talk about
• 3:27
  Speaker 2: something maybe even deeper, something much more personal, something closer
• 3:31
  Speaker 2: to our experience, and that's the question of life itself.
• 3:36
  Speaker 2: What is it? How can we talk about it, how
• 3:38
  Speaker 2: can we understand it? And how possibly could we discover
• 3:41
  Speaker 2: it on alien planets?
• 3:44
  Speaker 1: Oh, there's nothing better than talking about biology on a
• 3:46
  Speaker 1: physics podcast.
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  Speaker 3: Finally get into the good stuff.
• 3:49
  Speaker 2: With a couple of physicists. Right, and so today on
• 3:52
  Speaker 2: the podcast, we're going to be digging into the question
• 4:00
  Speaker 2: what is the physics of life? And we're gonna be
• 4:04
  Speaker 2: talking to Professor Sarah Amari Walker, author of the recent
• 4:07
  Speaker 2: book Life As No One Knows It, the physics of
• 4:10
  Speaker 2: Life's Emergence. How do you feel about talking about life
• 4:13
  Speaker 2: with two physicists?
• 4:14
  Speaker 1: Kelly wouldn't be my first choice, but no, I'm kidding.
• 4:18
  Speaker 1: I mean I'm very excited to hear a different perspective
• 4:20
  Speaker 1: on the question.
• 4:21
  Speaker 2: Well, I hope you brought a towel because this is
• 4:23
  Speaker 2: gonna be messy. It's always fascinating when physicists try to
• 4:28
  Speaker 2: walk into another field and explain things. And I feel
• 4:31
  Speaker 2: like often we do that because we think maybe there
• 4:34
  Speaker 2: is a simpler explanation, or because we think in these
• 4:37
  Speaker 2: like fundamental grounding in the basic principles of the universe.
• 4:41
  Speaker 2: How would you say? That's typically receives Kelly.
• 4:44
  Speaker 1: So you say fascinating, we say maddening, because so often physicists,
• 4:48
  Speaker 1: you know, seem to think that physics is up here
• 4:50
  Speaker 1: and biology is a few levels below. And if you
• 4:53
  Speaker 1: know physics, you must also know biology and maybe also chemistry,
• 4:56
  Speaker 1: so you can just wade in and solve all the
• 4:58
  Speaker 1: problems that the biologists are too silly to be able
• 5:01
  Speaker 1: to figure out. And so often there's you know, a
• 5:04
  Speaker 1: bit of condescension in the answers. I saw Freeman Dyson
• 5:08
  Speaker 1: give a talk once about group selection that was absolutely infuriating,
• 5:13
  Speaker 1: but because he clearly didn't understand.
• 5:15
  Speaker 3: What we were actually arguing about.
• 5:16
  Speaker 1: But anyway, today's conversation, you know, I read life as
• 5:20
  Speaker 1: no One Knows It by our author who we're talking
• 5:23
  Speaker 1: to today, and I really appreciated that she did not
• 5:26
  Speaker 1: have that condescending biology as easy attitude. She clearly appreciated
• 5:30
  Speaker 1: the nuances and was trying to meld it with physics.
• 5:34
  Speaker 2: As a physicist married to a biologist, I've definitely learned
• 5:37
  Speaker 2: to treat biology with great respect, good and not just
• 5:41
  Speaker 2: for the health of my marriage, but also just intellectually
• 5:44
  Speaker 2: because I appreciate it. And I think, you know, the
• 5:47
  Speaker 2: dirty secret about physicists walking into biology or chemistry is
• 5:52
  Speaker 2: that we became physicists not because we thought biology was
• 5:54
  Speaker 2: too easy, your chemistry was too simple, but because it's
• 5:57
  Speaker 2: too hard. You know, we can think about simple object
• 6:00
  Speaker 2: and put them together to try to describe the fundamental
• 6:02
  Speaker 2: nature of the universe, but now we need like ten
• 6:04
  Speaker 2: to the forty objects to explain like a drop of rain.
• 6:07
  Speaker 2: It's too complicated. I can't think about all of those
• 6:10
  Speaker 2: things at once. That's why I let to boil things
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  Speaker 2: down to like one particle touches one other particle, and
• 6:15
  Speaker 2: that's my whole universe.
• 6:17
  Speaker 4: Man.
• 6:18
  Speaker 1: I appreciate that you're trying to clean up the reputation
• 6:20
  Speaker 1: for your community, but I don't buy it at all.
• 6:23
  Speaker 1: But I do think that biology is complicated. You know,
• 6:27
  Speaker 1: we got the human microbiome that didn't solve all the
• 6:29
  Speaker 1: disease related problems we.
• 6:31
  Speaker 3: Thought it was going to solve.
• 6:32
  Speaker 1: Now we're working on the connect dome for the brain
• 6:34
  Speaker 1: and there's just many levels.
• 6:36
  Speaker 3: Man, it's complicated. We deserve respect.
• 6:39
  Speaker 2: Maybe one day we'll have an explanation for the human
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  Speaker 2: brain that goes all the way down to the fundamental physics,
• 6:44
  Speaker 2: but not yet. And so to take us on this
• 6:47
  Speaker 2: journey through the physics of life, whether we can understand
• 6:50
  Speaker 2: the nature of life, the meaning of life, how to
• 6:52
  Speaker 2: look for life, and how maybe even to discover life
• 6:55
  Speaker 2: on alien planets. We had a fun conversation with Professor
• 6:58
  Speaker 2: Sarah Amari Walker about her new book Life As No
• 7:01
  Speaker 2: One Knows It. Here's the interview. So then it's my
• 7:07
  Speaker 2: pleasure to welcome the podcast Sarah and Mauri Walker. She's
• 7:11
  Speaker 2: a theoretical physicist and deputy director for the Beyond Center
• 7:15
  Speaker 2: for Fundamental Concepts in Science, as well as a professor
• 7:18
  Speaker 2: at Arizona State University, and she's tackling some really hard
• 7:22
  Speaker 2: questions about the nature of life and consciousness and free
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  Speaker 2: will using physics in her new book. Sarah, thank you
• 7:29
  Speaker 2: very much for joining us today.
• 7:30
  Speaker 5: Yeah, I'm terrilled to be here. Thanks for having me
• 7:32
  Speaker 5: we're so glad to have you here.
• 7:34
  Speaker 2: So before we dig into the topic of your book,
• 7:37
  Speaker 2: I just wanted to get to know you a little
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  Speaker 2: bit better, especially because you're writing such a fascinating book.
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  Speaker 2: You're tackling really big, really hard, almost philosophical questions, but
• 7:46
  Speaker 2: you're using physics as a tool to do it. So
• 7:49
  Speaker 2: take us back to the beginning, like what got you
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  Speaker 2: into physics in the first place.
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  Speaker 6: I did not know I wanted to be a physicist
• 7:58
  Speaker 6: until I took my first physics class. So most of
• 8:00
  Speaker 6: my childhood I actually thought I was going to be
• 8:02
  Speaker 6: an artist. And I went to community college and I
• 8:06
  Speaker 6: knew at the time I liked science, so I just
• 8:08
  Speaker 6: took all the science classes i could, and I just
• 8:11
  Speaker 6: fell in love with physics. I just think it's absolutely
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  Speaker 6: amazing to think about the universe in these really deep,
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  Speaker 6: abstract ways and come to understand the world in a
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  Speaker 6: way that is almost existentially shocking to humans in some
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  Speaker 6: sense because it's so different than.
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  Speaker 5: The way that we thought it was.
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  Speaker 6: And the set of broad regularities that physics reveals I
• 8:29
  Speaker 6: think are really beautiful, And I guess I was really
• 8:32
  Speaker 6: excited about transforming something about the way that we think
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  Speaker 6: about the world and the way that physics does that.
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  Speaker 6: So I decided I wanted to be a physicist.
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  Speaker 2: Awesome. So we just had an episode recently about thinking
• 8:44
  Speaker 2: like a physicist what that means, and had a little
• 8:47
  Speaker 2: disagreement with Jorge about whether physicists think differently than other scientists.
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  Speaker 2: And so you say you're drawn to physics in particular
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  Speaker 2: because of the way they think about the world. How
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  Speaker 2: is that different? How does a physicist think about the
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  Speaker 2: universe different than a biologist?
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  Speaker 6: Yeah, and I'm not even sure if it comes down
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  Speaker 6: to training or who gets attracted to different fields. So
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  Speaker 6: I actually asked this question myself. But for me, I
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  Speaker 6: think a lot of the discussion about what physics is
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  Speaker 6: is mostly about what physics studies and not what physics
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  Speaker 6: is is a discipline, And so for me, when I
• 9:16
  Speaker 6: think about the history of physics and also what I'm
• 9:18
  Speaker 6: trying to do as a physicist moving into territory that's
• 9:21
  Speaker 6: traditionally not thought of as physics, you know, the thread
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  Speaker 6: I see there that I think is the commonality of like,
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  Speaker 6: what I think the core of physics is is building
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  Speaker 6: new and abstract explanations for the world around us. So
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  Speaker 6: I think physics to me is getting to like the
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  Speaker 6: very root of like the most fundamental explanations, and that
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  Speaker 6: process of doing that is you know, very unique to physics.
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  Speaker 6: I think is a discipline relative to other sciences. I
• 9:48
  Speaker 6: think other sciences also do that, But I think the
• 9:50
  Speaker 6: kind of training and the way that we're taught to
• 9:52
  Speaker 6: think and trying to embed these sort of abstract universal
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  Speaker 6: ideas in mathematics that are so broad, is pretty.
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  Speaker 5: Unique to what we call physics.
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  Speaker 6: Now, whether it will stay that way and it doesn't
• 10:04
  Speaker 6: become sort of more universal to the rest of science,
• 10:07
  Speaker 6: or even if that's the best way of doing science,
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  Speaker 6: as you know, a whole.
• 10:09
  Speaker 5: Other subject of debate.
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  Speaker 6: But for me, that's the essence of what physics is
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  Speaker 6: and why I still identify as a physicist, even though
• 10:16
  Speaker 6: the problems I study are so different than what has
• 10:19
  Speaker 6: traditionally been studied in physics.
• 10:22
  Speaker 1: When you've taken on a particularly in my mind, complicated
• 10:25
  Speaker 1: question to tackle. So my training is as a biologist,
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  Speaker 1: and in grad school, like the thing that you stay
• 10:32
  Speaker 1: up late drinking and talking about is you know, what
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  Speaker 1: is life? And how do you define species? Those are
• 10:39
  Speaker 1: like the two questions where at the end, we're all like,
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  Speaker 1: I don't know, nature doesn't fit into categories, and we
• 10:44
  Speaker 1: all laugh and go out dancing. And so what different
• 10:47
  Speaker 1: perspective does a physicist have on that question? And why
• 10:50
  Speaker 1: do we need an answer to this question as opposed
• 10:52
  Speaker 1: to the hand wavy nature doesn't fit into nice categories.
• 10:55
  Speaker 1: Let's just move on. Why do we need to do
• 10:57
  Speaker 1: better than that?
• 10:58
  Speaker 6: So I love the resolution that nature doesn't fit into categories,
• 11:02
  Speaker 6: and so so I love that that's like part of
• 11:04
  Speaker 6: the conclusion. I think that's actually a brilliant insight, because
• 11:06
  Speaker 6: I think we have a tendency to put problems in boxes,
• 11:09
  Speaker 6: because certain disciplines might become more adept to answering certain
• 11:12
  Speaker 6: aspects of questions. But there are some questions on the frontier,
• 11:15
  Speaker 6: like what is life that you know as a biologist,
• 11:18
  Speaker 6: maybe you don't need to know the answer to because
• 11:20
  Speaker 6: you can study biology on Earth without ever having a
• 11:23
  Speaker 6: resolution to that question. But this gets to your point
• 11:27
  Speaker 6: that you know there are some questions like the origin
• 11:30
  Speaker 6: of life that require an understanding of what life is,
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  Speaker 6: because that is not even a precisely defined question unless
• 11:36
  Speaker 6: we say that there's some category of nature quote unquote
• 11:39
  Speaker 6: that is life that we're trying to explain the origin of.
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  Speaker 5: And the other one is alien life are.
• 11:44
  Speaker 6: Designing completely radically new kinds of life, which I think
• 11:47
  Speaker 6: are not really decoupled problems with this idea of like
• 11:50
  Speaker 6: what other forms could life take besides the ones that
• 11:52
  Speaker 6: have evolved on Earth, besides the biology that we know it?
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  Speaker 6: And so I think those questions, surprisingly enough, don't seem
• 12:01
  Speaker 6: to have answers that fall just within the discipline of
• 12:04
  Speaker 6: biology as it's developed, because of exactly what you're pointing out,
• 12:07
  Speaker 6: that the boundaries of disciplines are kind of historically contingent,
• 12:10
  Speaker 6: and there's a lot of things that necessarily need to
• 12:13
  Speaker 6: come from chemistry or even computer science or physics or
• 12:15
  Speaker 6: all these other different disciplines. And so one thing I've
• 12:18
  Speaker 6: really come to notice in my career is that whatever
• 12:21
  Speaker 6: discussion we need to have about solving that problem doesn't
• 12:23
  Speaker 6: fit in any discipline as it's currently structured, And in
• 12:26
  Speaker 6: some sense, we might need to build a new discipline
• 12:28
  Speaker 6: to really think about this problem, because it's beyond the
• 12:31
  Speaker 6: boundaries of like the current confines of knowledge that we've
• 12:34
  Speaker 6: defined them so far. And that's exciting because it just
• 12:37
  Speaker 6: shows you that disciplines are kind of human centric categories
• 12:40
  Speaker 6: of nature. We might have to rewrite them.
• 12:43
  Speaker 2: Yeah, I mean we might argue, like, what is a
• 12:45
  Speaker 2: physicist anyway?
• 12:46
  Speaker 5: And people exactly that and just redefine that trump too.
• 12:51
  Speaker 5: That sounds good to me.
• 12:53
  Speaker 2: And you begin your really fun book with this question
• 12:57
  Speaker 2: and the sort of shocking suggestion that somebody made that
• 13:01
  Speaker 2: life doesn't exist. You know, if we can't categorize it,
• 13:04
  Speaker 2: if we can't define it, then maybe it doesn't exist
• 13:08
  Speaker 2: in the end. What is your definition of life?
• 13:11
  Speaker 5: Yeah?
• 13:12
  Speaker 6: So in my mind, I usually keep I think a
• 13:16
  Speaker 6: running list of maybe three to ten different definitions for life,
• 13:19
  Speaker 6: because I think pinning yourself to one too early is
• 13:21
  Speaker 6: a bit premature when we don't understand what we're talking about.
• 13:24
  Speaker 6: So usually my process is, you know, I really want
• 13:27
  Speaker 6: to have a theory, like a theory that explains the
• 13:31
  Speaker 6: broad patterns and regularities that we see across living forms
• 13:34
  Speaker 6: and is deep enough to help us understand the original life.
• 13:37
  Speaker 6: That's sort of my modality of thinking about these problems.
• 13:41
  Speaker 6: And so I've spent most of my career trying to
• 13:43
  Speaker 6: figure out what the structure of such a theory would be.
• 13:45
  Speaker 6: And obviously it has to be guided by some concept
• 13:47
  Speaker 6: of what you think life is. So it's a little circular,
• 13:49
  Speaker 6: but you're constantly redefining everything. So I'm often very hesitant
• 13:53
  Speaker 6: to pin one answer when people ask me what.
• 13:56
  Speaker 5: I think life is.
• 13:58
  Speaker 6: I but with all that that caveat, I can give
• 14:01
  Speaker 6: you kind of a conceptual framing of what I think
• 14:04
  Speaker 6: it is, but I wouldn't want to call it a definition.
• 14:07
  Speaker 6: And I think a lot of what the theory that
• 14:09
  Speaker 6: we're working on, in the kinds of experiments are pointing
• 14:11
  Speaker 6: to is that life is something about how information structures matter,
• 14:15
  Speaker 6: cross space and time is one way I say it,
• 14:17
  Speaker 6: but I think in the theory that we're building, it's
• 14:19
  Speaker 6: much more precise to say that life is the mechanism
• 14:22
  Speaker 6: by which the universe generates complexity. And we have a
• 14:24
  Speaker 6: very specific way of thinking about complexity, and it becomes
• 14:27
  Speaker 6: very historically contingent, and so I guess how the universe
• 14:30
  Speaker 6: uses memory that builds complex things in the future might
• 14:34
  Speaker 6: be the way I say it today, and if you
• 14:35
  Speaker 6: ask me tomorrow, I would say something else, because we're
• 14:37
  Speaker 6: still a work in progress about trying to get to
• 14:39
  Speaker 6: the bottom of what it is we're actually talking about.
• 14:41
  Speaker 1: So For a biologist, the argument almost always comes down to, well,
• 14:45
  Speaker 1: our virus is alive or not, so using the definition
• 14:48
  Speaker 1: that you just gave our viruses alive or not and why.
• 14:51
  Speaker 5: Yeah, So I think there's a little bit more nuanced.
• 14:54
  Speaker 6: So usually the way I talk about it is like,
• 14:56
  Speaker 6: are we talking about the physics of life? Are particular
• 14:58
  Speaker 6: instances of things that are living? And it might be like,
• 15:01
  Speaker 6: are you talking about gravitational physics and like the curvature
• 15:04
  Speaker 6: or space time, or are you talking about a gravitational
• 15:06
  Speaker 6: body that was generated by these sort of fundamental mechanisms
• 15:09
  Speaker 6: that we know that our universe works in. And I
• 15:10
  Speaker 6: think there are slightly different categories. So when I say
• 15:14
  Speaker 6: things are life, I mean anything that is the product
• 15:17
  Speaker 6: of an evolutionary process and requires memory and information from
• 15:22
  Speaker 6: the past to be able to actually make that thing
• 15:24
  Speaker 6: exist in the present. And I think viruses are certainly
• 15:27
  Speaker 6: that they require evolution to form, but the sort of
• 15:32
  Speaker 6: active process of generating complexity and generating novelty and contributing
• 15:35
  Speaker 6: to the sort of open ended growth of complexity that
• 15:39
  Speaker 6: we've observed in our biosphere.
• 15:40
  Speaker 5: I think things that do that are alive.
• 15:43
  Speaker 6: And I'm not sure that I would qualify a virus
• 15:45
  Speaker 6: as an individual agent as part of that creative process,
• 15:48
  Speaker 6: but it certainly is when you look at viruses as
• 15:51
  Speaker 6: components of ecological systems, for example. So a lot of
• 15:54
  Speaker 6: the things with issues about life is trying to pick
• 15:56
  Speaker 6: a scale and say this thing is life, when really
• 15:59
  Speaker 6: what you're talking about is a much more abstract universal
• 16:02
  Speaker 6: physics that even enables those things to exist in the
• 16:04
  Speaker 6: first place, to be selected. I think the reason that
• 16:07
  Speaker 6: viruses have been hard is because it's actually a category
• 16:10
  Speaker 6: error to try to partition a boundary and around a
• 16:12
  Speaker 6: virus and say is this a live or not when
• 16:13
  Speaker 6: you really should be looking at the continuity of the
• 16:15
  Speaker 6: evolutionary process and what it constructs.
• 16:18
  Speaker 2: Yeah, fascinating. I don't know that I agree that we
• 16:22
  Speaker 2: need a definition of life, but I do think it's
• 16:25
  Speaker 2: valuable to try, Like I think we need to have
• 16:28
  Speaker 2: the discussion in order to try to figure out what
• 16:30
  Speaker 2: this is like. If we agree or discuss, you know,
• 16:34
  Speaker 2: what life is, that shapes the way we think about
• 16:36
  Speaker 2: how to look for alien life and all these questions.
• 16:39
  Speaker 2: So I think it's very valuable to dig into the question,
• 16:41
  Speaker 2: even if we don't find an answer, and from that perspective.
• 16:46
  Speaker 2: I was really interested in the discussion you had at
• 16:47
  Speaker 2: the beginning of your book about, you know, the sort
• 16:49
  Speaker 2: of philosophy of what life might be. And you were
• 16:53
  Speaker 2: going through this discussion of like panpsychism, and there's this
• 16:56
  Speaker 2: one particular line that jumped out at me, said quote,
• 16:59
  Speaker 2: if life is not a property of matter, and material
• 17:03
  Speaker 2: things are what exists, then life does not exist. I
• 17:07
  Speaker 2: was wondering if you could expand on that thought. You know,
• 17:10
  Speaker 2: it doesn't it sort of ignore the possibility that life
• 17:13
  Speaker 2: could just be an emergent phenomenon, as you said, an
• 17:15
  Speaker 2: arrangement and complexity of basic bits that are not alive.
• 17:19
  Speaker 5: Yeah.
• 17:20
  Speaker 6: So part of the reason that I structured things in
• 17:24
  Speaker 6: specific ways early on was to kind of set up
• 17:26
  Speaker 6: some things that come later in the book. And one
• 17:28
  Speaker 6: thing I've noticed being a physicist trying to build new
• 17:32
  Speaker 6: physics is that we take for granted things as being
• 17:36
  Speaker 6: absolutely true about the universe that were actually invented by
• 17:40
  Speaker 6: human minds trying to correlate the way that their theories
• 17:43
  Speaker 6: behave with things they could actually measure. The example I
• 17:46
  Speaker 6: like to give is to think about mass. It seems
• 17:48
  Speaker 6: so obvious to us that mass is a physical property
• 17:50
  Speaker 6: of objects, and it is a physical property we talk
• 17:53
  Speaker 6: about in our theories of physics because we can measure it,
• 17:56
  Speaker 6: and because Galileo rolling balls down in climbplanes and other
• 17:59
  Speaker 6: people of his generation realized that that was the right
• 18:01
  Speaker 6: variable to construct theories of motion. I think, of course,
• 18:05
  Speaker 6: you can talk about life as just being an emergent property,
• 18:08
  Speaker 6: but you're never going to get to an objective understanding
• 18:11
  Speaker 6: of it as a physical phenomena unless you can tie
• 18:14
  Speaker 6: it to a measurement. And therefore whatever that thing is
• 18:18
  Speaker 6: has to become what we would call a material property
• 18:20
  Speaker 6: in our theories of physics, because now it's something we
• 18:23
  Speaker 6: measure that becomes a variable in our theory. Therefore it's physical.
• 18:27
  Speaker 6: And I think this has been the thing that's really
• 18:29
  Speaker 6: hard about thinking about the nature of life, is it
• 18:33
  Speaker 6: has forever been an epiphenomena and something we couldn't regularize
• 18:37
  Speaker 6: as part of a law of nature because we want
• 18:39
  Speaker 6: to adopt this view that surely it's just these emergent
• 18:42
  Speaker 6: informational patterns, but we can't measure them objectively.
• 18:47
  Speaker 5: And so my point saying that.
• 18:49
  Speaker 6: If you want to reduce life that way, then life
• 18:52
  Speaker 6: doesn't exist because you don't have an objective measurement. You
• 18:55
  Speaker 6: don't have a way of grounding whatever you're talking about
• 18:58
  Speaker 6: and testing it against reality and saying this is the
• 19:00
  Speaker 6: thing that emerges when life emerges.
• 19:02
  Speaker 2: If I could just stop you there, because I'm not
• 19:04
  Speaker 2: sure I'm following. Like, let's take a simpler example. You
• 19:07
  Speaker 2: know of thunderstorm. Thunderstorm is an emergent phenomenon, bubbling up
• 19:12
  Speaker 2: from the you know, the properties of particles and molecules
• 19:15
  Speaker 2: and all this kind of stuff. Clearly thunderstorms exist, right,
• 19:19
  Speaker 2: we agree. We can make measurements of them, their intensity,
• 19:21
  Speaker 2: all sorts of stuff. We can ground them, we can
• 19:23
  Speaker 2: write even some you know, mathematical expressions that describe them.
• 19:27
  Speaker 2: In some cases, how can we say thunderstorms exist and
• 19:31
  Speaker 2: we can make physical measurements of thunderstorms, but we can't
• 19:33
  Speaker 2: say the same thing about life?
• 19:35
  Speaker 5: Well, what would be the measurement that you're taking about life?
• 19:37
  Speaker 2: Though?
• 19:38
  Speaker 6: So the question with thunderstorms is it's a good example
• 19:40
  Speaker 6: because most of the measurements you're taking are things like
• 19:43
  Speaker 6: when velocity, you know, the temperature, Like these are like
• 19:46
  Speaker 6: physical measurements you can go in and take, and then
• 19:49
  Speaker 6: when you put those in some model of the thunderstorm,
• 19:51
  Speaker 6: you can actually model the thunderstorm's behavior. And that's same
• 19:53
  Speaker 6: physics works if you go on another planetary body and
• 19:57
  Speaker 6: account for differences in pressure and differences particular climate, you know,
• 20:01
  Speaker 6: in that gravitational field and things like that. The issue
• 20:05
  Speaker 6: with life is, you know, most people want to say that,
• 20:09
  Speaker 6: like when you're talking about chemistry, and like, life is
• 20:12
  Speaker 6: an organizational property of chemistry. When we look at its parts,
• 20:14
  Speaker 6: we don't see the things that we associate to life,
• 20:17
  Speaker 6: and so therefore life is an emergent property of those parts.
• 20:20
  Speaker 6: It's some organizational feature. But the problem is we don't
• 20:23
  Speaker 6: have the rules to go from the atoms and the
• 20:26
  Speaker 6: parts to that organizational feature in a universal way that
• 20:30
  Speaker 6: would allow us to go on another planet and measure
• 20:32
  Speaker 6: that property. It's very subjective the way that we talk
• 20:36
  Speaker 6: about it right now, and so it's okay if it's
• 20:39
  Speaker 6: subjective and not a material property. It might be that
• 20:42
  Speaker 6: there is no law of physics that allows us to
• 20:46
  Speaker 6: understand what life is. And it might be that life
• 20:48
  Speaker 6: is not a universal category of nature. It might just
• 20:51
  Speaker 6: be some weird emergent pattern that emerged on Earth and
• 20:53
  Speaker 6: there's no universality to it. But the argument that I'm
• 20:57
  Speaker 6: interested in, and the one I think that will actually
• 21:00
  Speaker 6: help us find alien life that's out there, because life
• 21:02
  Speaker 6: is a universal thing if it is, is that we
• 21:05
  Speaker 6: need to figure out what are the objective properties. And
• 21:08
  Speaker 6: when you do that, in some sense, you're making that
• 21:11
  Speaker 6: property material in a way that it becomes measurable. And
• 21:14
  Speaker 6: so that's sort of the interplay, Like life has not
• 21:17
  Speaker 6: been a material property. We've had this sort of vitalism
• 21:19
  Speaker 6: and the idea of a soul. But the question is
• 21:22
  Speaker 6: is that actually something that we can quantify, put into
• 21:26
  Speaker 6: a theory and also measure so that we can actually
• 21:29
  Speaker 6: say this is a real universal law like feature of
• 21:33
  Speaker 6: our universe.
• 21:34
  Speaker 1: But so then why go to life does not exist
• 21:36
  Speaker 1: as opposed to we don't understand it well enough yet.
• 21:40
  Speaker 6: Because the logical conclusion of the way that much of
• 21:44
  Speaker 6: the discussion has been is that we should assume life
• 21:47
  Speaker 6: does not exist. So in some sense, what I'm trying
• 21:49
  Speaker 6: to do is actually provoke, you know, like, if we
• 21:52
  Speaker 6: run the way we talk about things to their logical conclusion,
• 21:54
  Speaker 6: what are we really saying and is this actually what
• 21:57
  Speaker 6: we intend to say or do we want to say
• 21:59
  Speaker 6: there's something missing from our descriptions of nature, and maybe
• 22:02
  Speaker 6: we need to rethink from first principles what it is
• 22:04
  Speaker 6: that we're doing. So I actually think life does exist.
• 22:07
  Speaker 6: I was always perplexed that a lot of my colleagues,
• 22:10
  Speaker 6: if you really listen to the words they were saying,
• 22:12
  Speaker 6: were implying that it does not exist, and some of
• 22:14
  Speaker 6: them even saying it outright, that we should just not
• 22:17
  Speaker 6: think about the problem of defining life at all. Life
• 22:19
  Speaker 6: is not a category of nature. It's all reducible to
• 22:22
  Speaker 6: chemistry and physics. And I think that there's something deeply
• 22:26
  Speaker 6: missing in what life is and why we keep asking
• 22:30
  Speaker 6: this question. So why is it a question we ponder
• 22:32
  Speaker 6: in bars at night. It's probably because we feel intrinsically
• 22:35
  Speaker 6: we're missing something about, you know, the descriptions of the
• 22:38
  Speaker 6: world around us that's pretty fundamental. So that was always
• 22:41
  Speaker 6: my perspective. Now that might not be right, but I
• 22:44
  Speaker 6: think the way to find out if that's.
• 22:46
  Speaker 5: Right is try to go through the process.
• 22:48
  Speaker 6: Of building a theory you can test against something you
• 22:50
  Speaker 6: can measure, and trying to see if empirically you're actually
• 22:54
  Speaker 6: getting the right results, and if you're building a theory
• 22:56
  Speaker 6: that is all explanatory of the data that we see
• 23:00
  Speaker 6: and the observations we can make.
• 23:02
  Speaker 2: Right, So you're not saying I don't exist, or you
• 23:04
  Speaker 2: don't exist, or my cat doesn't exist. You're saying that
• 23:07
  Speaker 2: we don't have a clear and crisp definition of life
• 23:11
  Speaker 2: that lets us do things that we typically do in
• 23:13
  Speaker 2: physical theories, like we do with thunderstorms and we do
• 23:15
  Speaker 2: with cats, because we can make measurements of them. We
• 23:18
  Speaker 2: can't other than just like vaguely talking about sort of
• 23:22
  Speaker 2: fuzzy conceptual categories.
• 23:24
  Speaker 6: Yeah, I mean, in part, you know, the book is
• 23:26
  Speaker 6: an exercise of trying to turn a philosophical question into
• 23:29
  Speaker 6: a scientific one.
• 23:29
  Speaker 2: Yeah.
• 23:30
  Speaker 6: Right, So this has traditionally been a philosophical debate because
• 23:33
  Speaker 6: we don't have the things that we can pin the
• 23:35
  Speaker 6: debate into measurements to actually go test what it is
• 23:38
  Speaker 6: that we're talking about. And I think that's really the
• 23:41
  Speaker 6: critical transition that you know, most interesting science starts as
• 23:44
  Speaker 6: philosophical questions, and the period where the philosophy transitions to
• 23:49
  Speaker 6: science is always deeply interesting because we're asking exactly these
• 23:52
  Speaker 6: like really basic questions. It forces you to even ask
• 23:54
  Speaker 6: what science is, what is a measurement? What is a theory,
• 23:57
  Speaker 6: how do you build a new theory? Like what are
• 23:59
  Speaker 6: you even talking about? Ever when we talk about things
• 24:01
  Speaker 6: in science. So this is why it's exciting, but it
• 24:04
  Speaker 6: is really challenging because you're confronting things that you know,
• 24:08
  Speaker 6: we haven't known how to think about, and you're saying,
• 24:12
  Speaker 6: let's pin ourselves down and be precise and think about
• 24:15
  Speaker 6: it and ask how would we actually quantify and measure
• 24:18
  Speaker 6: this thing? And how will we build a theory that
• 24:20
  Speaker 6: describes this thing? And if you look at the history
• 24:23
  Speaker 6: of science, what excites me about it and why I
• 24:25
  Speaker 6: think any of the ideas that we're doing might be
• 24:27
  Speaker 6: on the right track is you know, every time that
• 24:29
  Speaker 6: that process has happened in the history of physics, we
• 24:31
  Speaker 6: come out the other side with a radically different conception
• 24:34
  Speaker 6: of what's going on than we had before. And like
• 24:37
  Speaker 6: my favorite example is like to think about you know,
• 24:40
  Speaker 6: saying terrestrial and celestial motion are the same thing. It's like,
• 24:43
  Speaker 6: you know, humans had been around for hundreds of thousands
• 24:45
  Speaker 6: of years seeing the stars and the night sky and
• 24:47
  Speaker 6: planets moving across the sky, and we never thought like
• 24:50
  Speaker 6: that would be you know, like the theory of gravitation,
• 24:52
  Speaker 6: it took, you know, centuries of measurement and coming to
• 24:57
  Speaker 6: you know, track the regularities of heavenly motions and be
• 25:00
  Speaker 6: able to get clocks that were precise enough timing to
• 25:03
  Speaker 6: actually build into an understanding of a theory of motion
• 25:07
  Speaker 6: and gravitation that allowed us to look up at this
• 25:09
  Speaker 6: guy and be like, oh, those things are actually moving
• 25:12
  Speaker 6: in the same way that things on Earth move. I mean,
• 25:14
  Speaker 6: these are radical conceptual leaps that our species has taken,
• 25:17
  Speaker 6: and I think to think that we're done doing that
• 25:19
  Speaker 6: is really premature. So I get excited about life and
• 25:22
  Speaker 6: when people say, well, isn't it just a pattern of motions,
• 25:24
  Speaker 6: and I'm like, well, of course it is. But we've
• 25:25
  Speaker 6: explained lots of those before in really deep and fundamental ways,
• 25:29
  Speaker 6: so maybe we should try again.
• 25:30
  Speaker 2: All right, I have lots more questions about this squishy topic,
• 25:33
  Speaker 2: but first let's take a quick break. Okay, we're back,
• 25:49
  Speaker 2: and we're trying to sort through the slimy questions of
• 25:51
  Speaker 2: the physics of life with Professor Sarah Amari Walker, author
• 25:55
  Speaker 2: of the book Life As No One Knows It Well
• 25:58
  Speaker 2: in terms of taking like a radical conceptual philosophical leaps.
• 26:01
  Speaker 2: I was very excited to see you open the door
• 26:04
  Speaker 2: to getting rid of reductionism. I mean, especially as a physicist,
• 26:09
  Speaker 2: you know, and as you described earlier, physics is so
• 26:12
  Speaker 2: ingrained in the idea of, like, let's find the microscopic
• 26:15
  Speaker 2: explanation for everything, start with what we hope is the
• 26:17
  Speaker 2: fundamental and everything will bubble up from there somehow dot
• 26:21
  Speaker 2: dot dot. Right. Leave that as an exercise for the engineers.
• 26:24
  Speaker 2: But in your book you actually consider the other approach,
• 26:28
  Speaker 2: the idea that like, maybe not everything is determined from
• 26:31
  Speaker 2: the smallest bits. Maybe what we see as like emergent
• 26:35
  Speaker 2: phenomena different scales or actually have their own different fundamental
• 26:39
  Speaker 2: description that like, you know, the universe isn't controlled by
• 26:42
  Speaker 2: the tiniest Can you talk a little bit about that.
• 26:44
  Speaker 2: I think that's probably a very unfamiliar concept for our
• 26:47
  Speaker 2: listeners who are used to, especially on this podcast, hearing
• 26:50
  Speaker 2: us talk about how tiny particles weave together to make
• 26:52
  Speaker 2: the universe.
• 26:54
  Speaker 6: Yeah, And I also love that view of reality. I
• 26:57
  Speaker 6: think it's like incredibly romantic, and I was trained in
• 26:59
  Speaker 6: that trich But thinking about life and really trying to
• 27:04
  Speaker 6: ask the question whether there were universal laws of life
• 27:06
  Speaker 6: like that speaks to me that we're looking for something
• 27:08
  Speaker 6: fundamental because it has to be universal and broadly explanatory
• 27:12
  Speaker 6: of any life in the universe, you start to ask
• 27:15
  Speaker 6: questions about the nature of what's fundamental. And as I
• 27:18
  Speaker 6: already alluded to before, a lot of the ways that
• 27:20
  Speaker 6: we think about what's fundamental are what things we can
• 27:24
  Speaker 6: go in the lab and test that build the structure
• 27:26
  Speaker 6: of our theories. And so some of the most precise
• 27:29
  Speaker 6: theories we have are these ones about microscopical physical motions,
• 27:34
  Speaker 6: but it doesn't mean that they explain everything. And one
• 27:37
  Speaker 6: of the points that I make in the book, which
• 27:39
  Speaker 6: is related to this sort of evolutionary progress of knowledge
• 27:43
  Speaker 6: that we've been talking about about, like disciplines changing over time,
• 27:45
  Speaker 6: is the notion of what's fundamental has actually changed with
• 27:48
  Speaker 6: our theories and with our measuring devices, and so I think,
• 27:52
  Speaker 6: you know, like the canonical example I like to give
• 27:54
  Speaker 6: is to think about atoms, which we thought for a
• 27:57
  Speaker 6: long time or indivisible units of matter, until we build
• 27:59
  Speaker 6: better technology and we realize they had parts. And so
• 28:01
  Speaker 6: I'm not sure that there's really a bottom to that process.
• 28:05
  Speaker 6: If string theory is right, obviously all the elementary particles
• 28:07
  Speaker 6: and things we think are you know, the full description
• 28:09
  Speaker 6: and reality are not right, but we can't validate theories
• 28:13
  Speaker 6: that go smaller because we don't have the technology yet.
• 28:17
  Speaker 6: So you know, that becomes a horizon of our current
• 28:21
  Speaker 6: understanding of reality, not something that's intrinsic to reality itself.
• 28:26
  Speaker 5: And if you.
• 28:26
  Speaker 6: Flip that around and you look at what you're trying
• 28:29
  Speaker 6: to do building a theory of life, life is built
• 28:32
  Speaker 6: out of these what we think are fundamental building blocks.
• 28:36
  Speaker 6: But the kinds of things that we want to understand
• 28:38
  Speaker 6: about life are much more about how the universe builds
• 28:41
  Speaker 6: complexity out of small parts. And it is the case
• 28:45
  Speaker 6: that if we can think about things that we can
• 28:48
  Speaker 6: measure there and build theories there, there's no reason to
• 28:51
  Speaker 6: think they're not just as fundamental as these other descriptions
• 28:54
  Speaker 6: of nature. So that's sort of like the baseline philosophy
• 28:57
  Speaker 6: I'm operating from. But the sort of core of your question,
• 29:00
  Speaker 6: I think is more about the emergence reductionism debate, not
• 29:03
  Speaker 6: the philosophy of measurement and what's fundamental. But I think
• 29:06
  Speaker 6: like those things are coupled, so I wanted to preface it,
• 29:09
  Speaker 6: But the emergence reductionism, you know, Phil Anderson had this
• 29:14
  Speaker 6: great essay which a lot of people have read and
• 29:16
  Speaker 6: love about this idea of more is different. You know,
• 29:18
  Speaker 6: even if you had that fundamental description, it doesn't mean
• 29:20
  Speaker 6: that as you go to these other layers like biology
• 29:24
  Speaker 6: and mind and technology, you're going to actually be able
• 29:27
  Speaker 6: to recover all the features of them. And so this
• 29:30
  Speaker 6: has been deeply perplexing. And what I suggest in the
• 29:33
  Speaker 6: book is one of the reasons you can't go between
• 29:36
  Speaker 6: scales is there actually are separate laws that describe the
• 29:40
  Speaker 6: idea of a hierarchy in the first place, that the
• 29:42
  Speaker 6: universe is actually constructing complexity, and that time needs to
• 29:45
  Speaker 6: be a component of that process. So if you remove
• 29:49
  Speaker 6: you know, evolutionary time, you know, you can talk about
• 29:54
  Speaker 6: me being an emergent property of my atoms, but I've
• 29:57
  Speaker 6: missed almost all of the physics that's in my body
• 30:00
  Speaker 6: and like the product of four billion years of evolution,
• 30:02
  Speaker 6: And so if I want to talk about me as
• 30:04
  Speaker 6: a fundamental structure, I need to talk about that feature,
• 30:08
  Speaker 6: not the atoms in my body. And so it's really
• 30:11
  Speaker 6: trying to invert the nature of like what is the
• 30:13
  Speaker 6: thing that actually explains this? You can say I'm an
• 30:16
  Speaker 6: emergent property, but it doesn't explain from those laws, those
• 30:20
  Speaker 6: lower level laws, how I got here and why I exist.
• 30:23
  Speaker 2: But does that mean that there is no explanation that
• 30:25
  Speaker 2: you have to have fundamental laws at every scale or
• 30:27
  Speaker 2: does it just mean those explanations eskeep us currently or
• 30:31
  Speaker 2: our current ability to do those calculations, and in some
• 30:34
  Speaker 2: future where we have an amazing supercomputer, we can model
• 30:37
  Speaker 2: everything from the tiniest bits.
• 30:39
  Speaker 6: I think it's both of the last things you said.
• 30:44
  Speaker 6: So I think there you cannot produce things like us
• 30:49
  Speaker 6: from the current structure the laws of physics. I don't
• 30:51
  Speaker 6: even think if you had a super massive supercomputer you
• 30:54
  Speaker 6: could do it. And a simple reason to cite that
• 30:57
  Speaker 6: is it would require more computation than is available in
• 30:59
  Speaker 6: all the resources of the entire universe, and yet the
• 31:03
  Speaker 6: universe builds things like us. And so I think that
• 31:06
  Speaker 6: right there suggests that something fundamental is missing, because you
• 31:10
  Speaker 6: could say, in principle, you could simulate it, and you
• 31:12
  Speaker 6: could generate our conversation that we're having right now, but
• 31:16
  Speaker 6: actually in principle is not in principle because it's not
• 31:18
  Speaker 6: even physically possible. So those things, to me suggest that
• 31:21
  Speaker 6: there's a huge gap in understanding. But I also think
• 31:26
  Speaker 6: fundamentally that the physics of what describes living things is
• 31:32
  Speaker 6: not encapsulated in the physics that we have of gravitational
• 31:37
  Speaker 6: fields or elementary particles or any sort of state of
• 31:40
  Speaker 6: the art in modern physics departments. I think it's just
• 31:42
  Speaker 6: not in those equations. And the reason I think it's
• 31:45
  Speaker 6: not in those equations is because life is very much
• 31:47
  Speaker 6: about the causation and time that's built into physical objects
• 31:51
  Speaker 6: that are complex. And if you think about what the
• 31:54
  Speaker 6: laws of physics revealed, they are often designed for specific problems,
• 31:59
  Speaker 6: and they tell you what's universal about a set of
• 32:02
  Speaker 6: questions like motion, for example, Like all moving objects you know,
• 32:06
  Speaker 6: can be described by mass and acceleration and you don't
• 32:10
  Speaker 6: care about the color of them, or how those objects
• 32:12
  Speaker 6: feel or other things. But that doesn't mean that those
• 32:15
  Speaker 6: laws explain everything about every object. And so you know,
• 32:20
  Speaker 6: the question is how many kinds of laws.
• 32:22
  Speaker 5: Of physics do we need?
• 32:24
  Speaker 6: What's the sort of universal set of things that they cover?
• 32:26
  Speaker 6: And I think life is presenting some real challenges for
• 32:30
  Speaker 6: the sort of current paradigm that we have in really
• 32:33
  Speaker 6: fundamental ways.
• 32:34
  Speaker 1: Again, as the biologist in the conversation, so I feel
• 32:38
  Speaker 1: like what I'm hearing is that we don't really understand
• 32:41
  Speaker 1: the physics stuff, but we know that life is something
• 32:44
  Speaker 1: that comes about through.
• 32:45
  Speaker 3: The process of evolution.
• 32:47
  Speaker 1: So I feel like we're back in an evolutionary biology lab. Yes,
• 32:51
  Speaker 1: how how does a physicist study it? Differently? Like is
• 32:54
  Speaker 1: the question what process results in something that natural selection
• 32:59
  Speaker 1: can then act? Like when when we, you know, put
• 33:02
  Speaker 1: the pedal to the metal or whatever, Like what what
• 33:05
  Speaker 1: do we do in a lab or on a board
• 33:08
  Speaker 1: for with equations?
• 33:09
  Speaker 3: That's different?
• 33:09
  Speaker 6: So this is a great question because ultimately, like Daniel's question,
• 33:14
  Speaker 6: can you know what will ultimately resolve it is? Does
• 33:17
  Speaker 6: providing a new explanation provide any new experimental tests and
• 33:20
  Speaker 6: things we couldn't do otherwise?
• 33:23
  Speaker 5: Because it doesn't. I could tell you, you know, I could.
• 33:25
  Speaker 6: Sit here all day arguing that there's other laws of
• 33:27
  Speaker 6: physics in life, and you know you could nod your head. Okay, Sarah,
• 33:31
  Speaker 6: but show me the proof, right, And I've been doing
• 33:32
  Speaker 6: this most of my career because you know, I have
• 33:34
  Speaker 6: like some conviction it's there, but we have to do
• 33:36
  Speaker 6: the hard work as scientists and show that.
• 33:38
  Speaker 5: It's useful for something.
• 33:40
  Speaker 6: And I think I think to your question, the challenge is,
• 33:44
  Speaker 6: you know, for the most part, we think about evolution
• 33:49
  Speaker 6: and selection as being things that life does. But that
• 33:53
  Speaker 6: doesn't allow us to explain the origin of life because
• 33:56
  Speaker 6: it has to be some spontaneous fluctuation with no machan
• 34:00
  Speaker 6: is a right and so, or it's just a rare fluke, right,
• 34:03
  Speaker 6: And then if it's a rare fluke, then you know,
• 34:05
  Speaker 6: none of this discussion is necessary because it's just something
• 34:08
  Speaker 6: that happened and there's no you know, explanation for it.
• 34:10
  Speaker 5: It was just, you know, a rare fluke event.
• 34:12
  Speaker 6: And I think this is one of the challenges because
• 34:14
  Speaker 6: that allows you know, intelligent design and other things to
• 34:17
  Speaker 6: be equivalent explanations to the scientific one, because we don't
• 34:20
  Speaker 6: have an explanation. So if you really want to explain it,
• 34:23
  Speaker 6: you kind of have to assume the original life is
• 34:25
  Speaker 6: itself a process of selection and evolution, so it's the
• 34:28
  Speaker 6: product of those kind of mechanisms, which means you need
• 34:31
  Speaker 6: an understanding of evolution that doesn't require a cellular architecture.
• 34:37
  Speaker 5: And this is the main challenge, right, So.
• 34:39
  Speaker 6: Before replication, before natural selection as we understand it now
• 34:44
  Speaker 6: in genes or the way it operates in biological populations
• 34:48
  Speaker 6: out of chemistry. How does an evolutionary system get constructed?
• 34:52
  Speaker 6: And so this is really the question that we're trying
• 34:55
  Speaker 6: to ask, is how do you get complexity when there
• 34:57
  Speaker 6: is none? And so so that's where we need a
• 35:01
  Speaker 6: new paradigm, because we need a mechanism of selection that
• 35:04
  Speaker 6: operates starting from simple molecules building into the complexity of life.
• 35:09
  Speaker 6: And that's really the theory that we're working on. This
• 35:11
  Speaker 6: assembly theory is really an approach to talking about selection
• 35:15
  Speaker 6: in the absence of like wind selection emerges, How to
• 35:18
  Speaker 6: selection actually start and how to selection build evolutionary systems
• 35:23
  Speaker 6: that we would recognize as evolving things. And so it's
• 35:25
  Speaker 6: suggesting a much more universal structure to the evolutionary process
• 35:29
  Speaker 6: then the particular things that we're selected and involved on
• 35:32
  Speaker 6: earth to understanding what are the general principles of the
• 35:36
  Speaker 6: kinds of systems that chemistry could generate that could lead
• 35:40
  Speaker 6: to this process of evolution that we recognize.
• 35:43
  Speaker 5: That's the question we're trying to answer.
• 35:45
  Speaker 6: And I think that one really does demand new physical
• 35:48
  Speaker 6: principles because you're asking out of I mean, people really
• 35:52
  Speaker 6: don't understand how big chemical space is. It is like
• 35:55
  Speaker 6: astronomically large. We also do a lot of stuff with
• 35:58
  Speaker 6: drug design with the same theories that trying to sell
• 36:00
  Speaker 6: the original life, which is kind of crazy. So I
• 36:02
  Speaker 6: deal with like you know, pharmaceutical drugs and this kind
• 36:05
  Speaker 6: of stuff. But like when cheminformatics go in and they
• 36:07
  Speaker 6: want to estimate the size of the chemical space they
• 36:09
  Speaker 6: have to search to look for new drug like properties,
• 36:12
  Speaker 6: it is insane. It's not small, it's insanely large, you know.
• 36:16
  Speaker 6: I think a really good example is like taxol is
• 36:19
  Speaker 6: a molecule I use a lot of times when I
• 36:21
  Speaker 6: give lectures that I picked up from my colleged Lee Kronin.
• 36:23
  Speaker 6: That molecule has an molecrooid of about eight hundred and
• 36:26
  Speaker 6: fifty three, you know, I think it has like forty
• 36:29
  Speaker 6: seven carbon atoms or fifty three or something that oxygen. Anyway, like,
• 36:33
  Speaker 6: if you wanted to do all the molecules with that
• 36:35
  Speaker 6: chemical formula alone, it would fill a volume of one
• 36:38
  Speaker 6: point five universes. So if you think about a planet
• 36:42
  Speaker 6: generating chemical chemistry in an unconstrained way, no selection, the
• 36:48
  Speaker 6: space of molecules that could be you know, just randomly
• 36:51
  Speaker 6: synthesized is so astronomically large, you would never expect anything
• 36:55
  Speaker 6: complex to recur twice. And so this is kind of
• 36:58
  Speaker 6: a key argument of the way that we constructed the theory.
• 37:01
  Speaker 6: When you start to see things that involve a lot
• 37:04
  Speaker 6: of constraints in the space of possibilities to get these
• 37:06
  Speaker 6: really complex, really improbable objects with a high abundance that
• 37:11
  Speaker 6: they're happening a lot, that's evidence of selection happening, and
• 37:16
  Speaker 6: that selection is actually the physics generating those objects. But
• 37:19
  Speaker 6: it's got to be much deeper than what we just
• 37:20
  Speaker 6: see and involved architectures that we have, like with the cell,
• 37:23
  Speaker 6: because that comes fairly late in the original life process.
• 37:25
  Speaker 2: So I understand that the space is very large, right,
• 37:28
  Speaker 2: Obviously there's lots of different combinations. Chemistry is complicated. But
• 37:31
  Speaker 2: how do we know what's improbable or what's unusual because
• 37:35
  Speaker 2: the space is so large and we haven't explored it, right,
• 37:38
  Speaker 2: And you say, for example, like the existence of rockets
• 37:40
  Speaker 2: in the universe is a sign of like conscious thought
• 37:43
  Speaker 2: or whatever, But you know, how do we know them
• 37:45
  Speaker 2: that that's the case? How do we know that other
• 37:47
  Speaker 2: arrangements that our particular planet didn't explore don't lead to
• 37:50
  Speaker 2: greater complexity or more interesting things existing in the universe.
• 37:54
  Speaker 6: So your question is a good one, and I think
• 37:57
  Speaker 6: a lot of us have sort of embedded in the
• 38:00
  Speaker 6: way that we think about the world. And this actually
• 38:02
  Speaker 6: comes from the way that we think about physics. It's
• 38:03
  Speaker 6: sort of a heritage legacy actually from the eighteen hundreds
• 38:08
  Speaker 6: and the development of statistical mechanics and the idea of
• 38:10
  Speaker 6: spontaneous fluctuation. We have an idea in our minds that
• 38:14
  Speaker 6: anything of arbitrarily complexity can spontaneously fluctuate into existence. And
• 38:20
  Speaker 6: this is the whole impetus of the Boltzmant brain argument,
• 38:22
  Speaker 6: which actually was proposed by Eddington. Originally is kind of
• 38:24
  Speaker 6: a mocking of Boltzmann's ideas, but then became something that
• 38:28
  Speaker 6: physicists took very seriously and tried to put in our
• 38:30
  Speaker 6: cosmological models. And so the challenge there is, of course,
• 38:35
  Speaker 6: we can say, you know, a planet can make an
• 38:38
  Speaker 6: arbitrarily complex molecule, right. I can make that statement and
• 38:42
  Speaker 6: it seems intuitively logical. But if I said, you know,
• 38:45
  Speaker 6: Mars is going to generate a cell phone tomorrow, you
• 38:48
  Speaker 6: would kind of laugh at me, right, like that's a
• 38:50
  Speaker 6: silly statement. Is there really a chance that we could
• 38:53
  Speaker 6: just find the planet Mars generating a cell phone, and
• 38:56
  Speaker 6: like not a cell phone, but just something equivalent amount
• 38:59
  Speaker 6: of organization and evolutionary processes, Like a cell phone takes
• 39:05
  Speaker 6: four billion years to make on a planet. It takes
• 39:07
  Speaker 6: a lot of selection to get to that very specific object.
• 39:09
  Speaker 6: It's really designed for our biology. The technology is built
• 39:12
  Speaker 6: on our planetary resources. Like everything about that object is
• 39:17
  Speaker 6: a direct consequence of the fact that we've had four
• 39:20
  Speaker 6: billion years of evolution along a specific trajectory on our planet.
• 39:24
  Speaker 6: And so to assume an object like that can just
• 39:26
  Speaker 6: form random chance somewhere in the universe, I think is
• 39:30
  Speaker 6: a major it's a major misstep in our reasoning.
• 39:33
  Speaker 5: About how reality works.
• 39:35
  Speaker 6: We have no evidence that it can actually happen outside
• 39:38
  Speaker 6: of evolution, and so a lot of people will try
• 39:41
  Speaker 6: to challenge the way that we're building the formalism on
• 39:44
  Speaker 6: this idea that something complex can just be made on
• 39:47
  Speaker 6: a planet in the absence of evolution and selection. And
• 39:51
  Speaker 6: I can just say back to that, like, give me
• 39:52
  Speaker 6: the evidence the universe builds an that requires like information
• 39:57
  Speaker 6: to specify it, because to me, what that argument when
• 39:59
  Speaker 6: it tail is actually the equivalent of intelligent designs, as
• 40:02
  Speaker 6: the universe has the design of every object at every
• 40:05
  Speaker 6: point in the universe. What I'm suggesting is that selection
• 40:09
  Speaker 6: and evolution are required to build information specific to objects
• 40:12
  Speaker 6: before they can exist.
• 40:13
  Speaker 2: Right, And I agree with that. I'm not arguing that
• 40:17
  Speaker 2: cell phones should appear on Mars, so that would be probable,
• 40:20
  Speaker 2: and I appreciate that. You know, complexity comes as like
• 40:23
  Speaker 2: the tip of the pyramid built on the base of
• 40:25
  Speaker 2: like a huge amount of things that came before it. Absolutely,
• 40:29
  Speaker 2: But what I'm wondering is whether we can argue that
• 40:32
  Speaker 2: life on Earth is unusually complex. We don't know with
• 40:36
  Speaker 2: the space of possibilities is maybe if we go out
• 40:38
  Speaker 2: in the universe we discover, wow, we're actually quite primitive.
• 40:42
  Speaker 2: The complexity here on Earth is where in the backwater,
• 40:45
  Speaker 2: I mean compared to Mars. Sure, but like you were
• 40:47
  Speaker 2: saying that, you know, what we've achieved here on Earth
• 40:50
  Speaker 2: or what's happened here on Earth is unusually complex. But
• 40:53
  Speaker 2: how do we know that?
• 40:54
  Speaker 5: Oh, where's the prior?
• 40:55
  Speaker 6: I see, So I was referencing that with respect to
• 40:58
  Speaker 6: an abiotic prior. Imagine you don't have an evolutionary system, right,
• 41:02
  Speaker 6: So I think we're talking cross purposes about the question,
• 41:04
  Speaker 6: So I just want to kind of frame it precisely.
• 41:06
  Speaker 6: So if you just look at, you know, a system
• 41:08
  Speaker 6: that doesn't have evolutionary selection, the sort of framing that
• 41:13
  Speaker 6: we have the key conjectures, there's a maximum complexity a
• 41:17
  Speaker 6: non living system could build, and it can't build any
• 41:19
  Speaker 6: more than that until selection and sort of feedback on
• 41:21
  Speaker 6: the structure and like self reproducing systems emerge that actually
• 41:24
  Speaker 6: constrain themselves to.
• 41:25
  Speaker 5: Be able to perpetuate.
• 41:26
  Speaker 6: Right, what you're asking is, if that process starts, are
• 41:31
  Speaker 6: we more or less complex than that typical process? And
• 41:34
  Speaker 6: I think we don't know the answer to that obviously,
• 41:36
  Speaker 6: but I think what I can say is from the
• 41:41
  Speaker 6: sort of structure of the physical laws in the theory
• 41:45
  Speaker 6: that we're building and testing, every evolutionary system will have
• 41:51
  Speaker 6: to climb.
• 41:52
  Speaker 5: The ladder of complexity.
• 41:54
  Speaker 6: So there is no like major jump where you just
• 41:56
  Speaker 6: get to be like the most complex thing in the
• 41:58
  Speaker 6: universe by skipping steps. So that a question of did
• 42:01
  Speaker 6: life start in the universe on any planets much before
• 42:04
  Speaker 6: us or have an accelerated process moving through the sort
• 42:08
  Speaker 6: of complexity cascade. And I don't think anyone knows the
• 42:12
  Speaker 6: answer to that question. That's one of the reasons that
• 42:14
  Speaker 6: we want to understand this physics so we can actually
• 42:17
  Speaker 6: make predictions about what that process looks like on other planets.
• 42:20
  Speaker 6: And I think we're at this stage where I'm hopeful,
• 42:23
  Speaker 6: you know, in the next I don't know, ten years,
• 42:25
  Speaker 6: maybe we might be able to say something meaningful about
• 42:27
  Speaker 6: the first steps from geochemistry using this kind of theoretical construction,
• 42:31
  Speaker 6: like these kind of steps about like what are the
• 42:33
  Speaker 6: first mechanisms of selection that emerge in chemistry and what
• 42:36
  Speaker 6: do they look like in different planetary context But saying
• 42:38
  Speaker 6: something about that whole cascade is basically simulating the entire
• 42:41
  Speaker 6: evolutionary process, you know, from the geochemical original life into
• 42:46
  Speaker 6: technology on another planet.
• 42:48
  Speaker 5: And I don't think that's actually computationally feasible.
• 42:50
  Speaker 6: I think we have to discover other life to answer
• 42:52
  Speaker 6: that question, which is why we need a theory to
• 42:55
  Speaker 6: know what we're looking for.
• 42:56
  Speaker 1: So would geologists come across molecules that look complicated or
• 43:00
  Speaker 1: chemistry was the class I did not get as in, yeah,
• 43:03
  Speaker 1: so how do you know that you've got like a
• 43:04
  Speaker 1: complicated molecule that's life or do you get similarly complicated
• 43:08
  Speaker 1: molecules in the geology lab that are not alive.
• 43:10
  Speaker 6: It's a non trivial question, highly non trivial, and I
• 43:14
  Speaker 6: think part of it comes from the different uses of
• 43:16
  Speaker 6: the word complexity. So I think a lot of my
• 43:19
  Speaker 6: planetary science colleagues and geologists would say, of course we
• 43:22
  Speaker 6: find complexity in chemical systems, we see it all the time.
• 43:26
  Speaker 6: The kind of complexity that they're talking about is often
• 43:28
  Speaker 6: what we see in prevotic chemistry experiments also, which is
• 43:32
  Speaker 6: oftentimes like the most problematic thing you see in prevatic chemistries.
• 43:35
  Speaker 6: If you just run an unconstrained reaction, you get what
• 43:38
  Speaker 6: we call a tar, which is a non differentiated mess
• 43:41
  Speaker 6: of molecules. So these kind of systems can generate a
• 43:45
  Speaker 6: lot of molecular diversity, but it tends to be things
• 43:49
  Speaker 6: that would be low complexity as individual molecules, and for
• 43:53
  Speaker 6: things that are higher complexity, you don't see a lot
• 43:55
  Speaker 6: of them. And that's very different than what we see
• 43:58
  Speaker 6: in life, which is we see, you know, there's a
• 44:01
  Speaker 6: lot of diversity molecules in life, but compared to the
• 44:03
  Speaker 6: size of the chemical space that that could be you know,
• 44:06
  Speaker 6: equivalent structure or like molecular weight or you know, number
• 44:10
  Speaker 6: of chiral centers, or you know number of elements in
• 44:13
  Speaker 6: the molecule, like any of these features you might say
• 44:15
  Speaker 6: is equivalent molecules. You see very very very very low
• 44:19
  Speaker 6: diversity in biology. And so what biology does is it
• 44:23
  Speaker 6: builds molecules that are deep in the space of chemistry,
• 44:26
  Speaker 6: like they require a lot of parts to build the
• 44:28
  Speaker 6: specific molecule. So that molecule is complex in an evolutionary sense.
• 44:33
  Speaker 6: It's found in high abundance, but there's not a huge
• 44:36
  Speaker 6: diversity of exploring in an unconstrained way the space of
• 44:39
  Speaker 6: all molecules. So I think the kind of complexity we
• 44:43
  Speaker 6: talk about in a planetary science sense doesn't discover the
• 44:47
  Speaker 6: kind of complexity that biology generates.
• 44:49
  Speaker 2: So let's dig into that a little bit, because I
• 44:52
  Speaker 2: think that's really at the core of the argument in
• 44:54
  Speaker 2: your book, right, this concept of complexity and how we
• 44:58
  Speaker 2: discover it and what it means for life to be complex.
• 45:01
  Speaker 2: So you're saying that life is something that uses a
• 45:04
  Speaker 2: relatively small number of building blocks but puts them together
• 45:09
  Speaker 2: in a way that's very complex. Right. The complexity comes
• 45:12
  Speaker 2: from the arrangements of a few bits, not from the
• 45:15
  Speaker 2: inherent complexity of the pieces and that of the chemical
• 45:19
  Speaker 2: space that exists out there. As you're saying earlier, it
• 45:22
  Speaker 2: uses a tiny, little, very tiny, yeah, very tiny little
• 45:25
  Speaker 2: aspect of that. And so again I wonder like, how
• 45:29
  Speaker 2: do we know how unusual that is, or how special
• 45:32
  Speaker 2: that is, how distinct that is? How do we know
• 45:34
  Speaker 2: that it's not possible using other building blocks to create complexity?
• 45:39
  Speaker 2: How do we know that complexity doesn't always arise if
• 45:42
  Speaker 2: you start from you know, basic bits.
• 45:44
  Speaker 6: Yeah, this is the more exciting question, and it's actually
• 45:47
  Speaker 6: you know, the one Experimentally, I'm really interested in if
• 45:50
  Speaker 6: you designed an original life experiment that was modeling a
• 45:53
  Speaker 6: planetary environment and it was unconstrained and selection and evolutionary
• 45:59
  Speaker 6: processes emerging, which in the system just by the dynamics
• 46:02
  Speaker 6: of the chemistry, would it discover the same biochemistry?
• 46:06
  Speaker 5: And I'm not convinced it would. I think chemical space
• 46:08
  Speaker 5: is so large that there are a lot.
• 46:10
  Speaker 6: Of potential chemical architectures for life that could be quite different,
• 46:14
  Speaker 6: but we haven't discovered them yet. Because life on Earth,
• 46:19
  Speaker 6: you know, had one solution that allowed it to perpetuate
• 46:23
  Speaker 6: itself and had to use that architecture for billions of years.
• 46:26
  Speaker 6: And you know, the question is if the original life
• 46:29
  Speaker 6: happened again, would it discover the same architecture or not?
• 46:31
  Speaker 5: And nobody knows the answer to that.
• 46:33
  Speaker 6: I think that's an experimental question, you know, and that's
• 46:36
  Speaker 6: one that we want to ask because you know, part
• 46:38
  Speaker 6: of the thing I you know, try to really highlight
• 46:41
  Speaker 6: in the discussion in the book, but I'm also really
• 46:43
  Speaker 6: trying to just pitch to people as an experimental program
• 46:46
  Speaker 6: that we need to do because it requires a lot
• 46:47
  Speaker 6: of investment of technology and resources, is to think through
• 46:51
  Speaker 6: how we would build an experimental program to discover alien
• 46:53
  Speaker 6: life in the lab and the idea of there exactly
• 46:57
  Speaker 6: in the lab. Yes, it's exactly what you're saying though,
• 47:00
  Speaker 6: like we don't know if life could exist in other chemistries.
• 47:03
  Speaker 6: If you do a proper original life experiment and you
• 47:06
  Speaker 6: really want to know the spontaneous probability for a universe
• 47:09
  Speaker 6: to generate life, you can't just cherry pick and use
• 47:12
  Speaker 6: them like our structures that were selected on Earth and
• 47:13
  Speaker 6: say I'm going to make these because you're inducing selection
• 47:16
  Speaker 6: based on what was produced on Earth right prior knowledge
• 47:20
  Speaker 6: of it. You really want to see from chemistry, what
• 47:22
  Speaker 6: would it generate without any intervention from us, as you know,
• 47:28
  Speaker 6: designers of the chemistry, knowing what we know of Earth life.
• 47:31
  Speaker 6: So I think the original life problem is actually that's
• 47:34
  Speaker 6: exactly what it is, is an experimental problem to try
• 47:38
  Speaker 6: to discover what is the mechanism chemistry generates living forms.
• 47:44
  Speaker 6: And if you know that mechanism, is it universally going
• 47:47
  Speaker 6: to converge on what life on Earth did?
• 47:49
  Speaker 5: Or are there many solutions? Because this space is so huge.
• 47:52
  Speaker 1: I'm sure you could get a lot of evolutionary biologies
• 47:54
  Speaker 1: very excited if you could repeatedly generate them.
• 47:57
  Speaker 5: You need their talent, so that's good.
• 48:00
  Speaker 6: Yeah, I think you know, part of my motivation with right,
• 48:03
  Speaker 6: it's hard to write a book, right, And for first
• 48:07
  Speaker 6: and foremost I'm about the science, Like I just really
• 48:09
  Speaker 6: want to solve the original life. So part of my
• 48:10
  Speaker 6: motivation is to get people excited about like what are the.
• 48:12
  Speaker 5: Actual critical challenges here?
• 48:14
  Speaker 6: And I think I think this one is like the
• 48:17
  Speaker 6: main one is like what does the experimental program look
• 48:19
  Speaker 6: like that solves the original life? And how related is
• 48:22
  Speaker 6: it to all these other questions that we're talking about,
• 48:24
  Speaker 6: And for me, it is going to require you know,
• 48:27
  Speaker 6: really intense technological infrastructure, building digital chemistry and AI driven
• 48:32
  Speaker 6: robotic chemistry to actually search chemical space like a search engine,
• 48:36
  Speaker 6: and then looking for these kind of chemistries and when
• 48:38
  Speaker 6: they undergo selection and they start emerging things that we
• 48:41
  Speaker 6: might call life. And the reason for having to build
• 48:44
  Speaker 6: a theory in part besides all the reasons I have
• 48:47
  Speaker 6: as a physicist, is if the chemistry is radically different,
• 48:50
  Speaker 6: how do you even know it's a living thing. And
• 48:52
  Speaker 6: so we have to be able to measure evolution in
• 48:54
  Speaker 6: molecules agnostic to what molecules evolution creates, and know that
• 48:59
  Speaker 6: they have of a comparable level of selection in them
• 49:04
  Speaker 6: to say that, you know, this is past the threshold
• 49:06
  Speaker 6: that we expect it to be a living form versus
• 49:10
  Speaker 6: you know what we expect a biogs systems that aren't
• 49:12
  Speaker 6: evolving to be able to generate.
• 49:14
  Speaker 2: And so this is sort of the core argument of
• 49:16
  Speaker 2: your book. You describe assembly theory, where you measure the
• 49:20
  Speaker 2: complexity of something as the number of steps it takes
• 49:23
  Speaker 2: essentially to build some of the shortest path to go
• 49:25
  Speaker 2: from building blocks to this thing. Right, and then you
• 49:29
  Speaker 2: do this thing where you say, well, anything above fifteen
• 49:32
  Speaker 2: steps is life, and anything below fifteen steps is not life.
• 49:36
  Speaker 2: And I was with you until I got to that point.
• 49:38
  Speaker 2: I found myself asking, as you actually did in the book, like, well,
• 49:41
  Speaker 2: why fifteen doesn't it feel sort of arbitrary? How do
• 49:46
  Speaker 2: we know it's fifteen?
• 49:46
  Speaker 5: It's like it should be forty two, right, forty two
• 49:49
  Speaker 5: would have been better?
• 49:50
  Speaker 2: Yeah, give is a description of that thought process.
• 49:53
  Speaker 5: No, it's a good question.
• 49:54
  Speaker 6: So fifteen is maybe an approximate bound, right, But where
• 49:57
  Speaker 6: that comes from is actually the experimental data. It's not
• 50:00
  Speaker 6: like anointed you know, like the assembly theory cult said
• 50:03
  Speaker 6: it's going to be fifteen.
• 50:04
  Speaker 5: It's just like, you know, we build cult.
• 50:07
  Speaker 6: I know, right, and there is no cult actually, Like
• 50:10
  Speaker 6: it's really funny because you know, there's a lot of
• 50:13
  Speaker 6: challenges we're getting developing this theory from people picking it
• 50:15
  Speaker 6: apart different ways, which we love.
• 50:17
  Speaker 5: But I don't think anyone's harder on it than the
• 50:18
  Speaker 5: people we have actually working on it. So it's like,
• 50:21
  Speaker 5: which is the best kind of science?
• 50:22
  Speaker 6: Right, Like you pick apart every idea and you re
• 50:24
  Speaker 6: evaluate everything you're doing at every step.
• 50:26
  Speaker 2: Well, if you're denying the existence of the cult, that
• 50:28
  Speaker 2: tells me that the cult definitely exists.
• 50:30
  Speaker 5: Oh sure, yeah, I know, right, you're just I'm going
• 50:32
  Speaker 5: to wink wink.
• 50:33
  Speaker 2: Wink, tell us about the data that supports the choices.
• 50:37
  Speaker 5: Yeah, so that comes from the data.
• 50:39
  Speaker 6: So this idea of this minimal pass so involves you recursions.
• 50:43
  Speaker 6: So the idea is like, it's easier with lego than chemistry,
• 50:46
  Speaker 6: you know, because most of us aren't chemists. So it's like,
• 50:48
  Speaker 6: you think you're building a particular lego structure. I usually
• 50:51
  Speaker 6: use Howkwarts castle as people know, but like the taj
• 50:53
  Speaker 6: Ma hall or whatever, you know, building you might prefer,
• 50:56
  Speaker 6: you know, you wouldn't expect to form it by randomly
• 50:59
  Speaker 6: shaking the building blocks in the box. Right, there's instructions
• 51:01
  Speaker 6: that allow you to make it. In assembly theory, you
• 51:04
  Speaker 6: realize if you take the instructions, there's actually lots of
• 51:06
  Speaker 6: different ways of getting to the end root if you
• 51:08
  Speaker 6: don't use the instructions. Right, So in assembly theory, we
• 51:11
  Speaker 6: have to ground it in something that's always there about
• 51:14
  Speaker 6: that structure, and not just because you had a particular
• 51:17
  Speaker 6: set of instructions in a particular environment to make that.
• 51:20
  Speaker 6: And so we do this based on this minimal path
• 51:22
  Speaker 6: idea and the assumptions of the minimal path are you
• 51:25
  Speaker 6: can only build things if you already build them, and
• 51:27
  Speaker 6: you want to try to find the shortest path where
• 51:29
  Speaker 6: you're reusing parts you've built already to build the final structure,
• 51:32
  Speaker 6: so very minimal set of assumptions. It turns out that
• 51:36
  Speaker 6: feature you can actually measure in the lab, and we
• 51:40
  Speaker 6: measured it in the paper that we tried to do
• 51:42
  Speaker 6: biosignature of validation in using mass spectrometry, but there was
• 51:45
  Speaker 6: a later paper from Leekronin's group that came out showing
• 51:48
  Speaker 6: that you can also measure assembly index this shortest path
• 51:51
  Speaker 6: measure with NMR and infrared.
• 51:53
  Speaker 5: So we have a strong sort of.
• 51:55
  Speaker 6: Conviction right now as a running assumption with the theory
• 51:58
  Speaker 6: that it's an intrinsic property a molecule. This feature, it's
• 52:01
  Speaker 6: one that you can measure with independent measuring apparatus. It
• 52:04
  Speaker 6: doesn't depend on where the environment where the molecule was made,
• 52:07
  Speaker 6: So that gives us some of the baseline criteria of
• 52:10
  Speaker 6: something being an objective measure of the amount of selection
• 52:13
  Speaker 6: in an object, and then what you have in a
• 52:15
  Speaker 6: molecule that you can go and measure in the labs.
• 52:18
  Speaker 6: So you know, if I went to Enceladus and I
• 52:21
  Speaker 6: measured it, you know, the molecule would have the same
• 52:23
  Speaker 6: value it would have on Earth. Okay, so that's important.
• 52:26
  Speaker 6: And so the question is then if you use that,
• 52:29
  Speaker 6: does it actually separate out things that are uniquely produced
• 52:33
  Speaker 6: by life from not And so to do this, Lee's
• 52:37
  Speaker 6: lab took a bunch of samples, you know, abiotic and biotic,
• 52:42
  Speaker 6: even some Scotch whiskey, and then they had some samples
• 52:45
  Speaker 6: that were blinded from NASA that were both biological and
• 52:48
  Speaker 6: non biological, sort of an adversarial test case. And what
• 52:51
  Speaker 6: they did is they use this mass spec method to
• 52:54
  Speaker 6: measure assembly index on the actual samples, and they showed
• 52:57
  Speaker 6: that using assembly theory bind with the mass spect data,
• 53:01
  Speaker 6: they only saw molecules that were more than fifteen steps
• 53:08
  Speaker 6: in this minimal path being produced by living samples. And
• 53:13
  Speaker 6: this gets to the complicated versus complexity issue because one
• 53:16
  Speaker 6: of the adversarial samples that NASA cent was actually Murchison meteorite,
• 53:21
  Speaker 6: which oftentimes in prebatic chemistry literature you will see as
• 53:24
  Speaker 6: being like the most complex sample of prebatic chemistry, and
• 53:27
  Speaker 6: it was still below fifteen for the molecules in the sample.
• 53:32
  Speaker 6: So what you see in Merchison is again this tar
• 53:34
  Speaker 6: You have a lot of molecules, but none of them
• 53:36
  Speaker 6: are high abundance and a high assembly. And so it's
• 53:40
  Speaker 6: not just that the molecule is high assembly. You actually
• 53:43
  Speaker 6: have to have it in a high enough abundance to
• 53:47
  Speaker 6: say that it was selected in that particular context.
• 53:50
  Speaker 2: Right, So, but does that mean that if I find
• 53:53
  Speaker 2: some sample on an alien planet and you measure its
• 53:56
  Speaker 2: assembly index and it comes out to forty two, You're
• 53:59
  Speaker 2: going to be like this life? Are you proposing this
• 54:01
  Speaker 2: as a definition of life? A discrow way to decide?
• 54:05
  Speaker 6: I think that would be the ultimate outcome based on
• 54:08
  Speaker 6: the path that we're on, but I think we have
• 54:09
  Speaker 6: a lot more work to do to be like definitively
• 54:12
  Speaker 6: there is a threshold and assembly spaces above which you
• 54:15
  Speaker 6: would say that a sample was life or not. And
• 54:19
  Speaker 6: that's sort of where we're going. So right now, I
• 54:20
  Speaker 6: would be pretty high confident if you discovered something on
• 54:23
  Speaker 6: Enceladus that was forty two that.
• 54:26
  Speaker 5: It could only be produced by life.
• 54:28
  Speaker 6: But the sort of next steps are really actually theoretically
• 54:32
  Speaker 6: predicting why it should be the number fifteen and what
• 54:35
  Speaker 6: number it should be. If you have variations in your
• 54:37
  Speaker 6: elemental distributions or other things about the structure of the
• 54:40
  Speaker 6: assembly space, which is the underlying mathematical structure that we
• 54:43
  Speaker 6: build this whole formalism out of. And so one of
• 54:45
  Speaker 6: the projects in my lab right now is actually trying
• 54:48
  Speaker 6: to quantify why there's a transition in assembly theory at
• 54:52
  Speaker 6: the particular assembly index values that we see and might
• 54:55
  Speaker 6: see in different systems.
• 54:56
  Speaker 2: Because, as you say, the chemical space is very large.
• 54:59
  Speaker 2: Is this structures out there that are quite complex but
• 55:04
  Speaker 2: that nobody would call alive.
• 55:05
  Speaker 6: Right, So there are many such structures, right, So it's
• 55:09
  Speaker 6: not necessarily that the threshold must be at fifteen. That's
• 55:12
  Speaker 6: where we have for the kinds of chemistry that we
• 55:15
  Speaker 6: test in the lab so far. When we have a
• 55:18
  Speaker 6: general theory, which we're working on very fervently right now
• 55:22
  Speaker 6: with our teams, we would be able to predict, based
• 55:25
  Speaker 6: on the sort of elemental composition and other features of
• 55:28
  Speaker 6: your chemistry, where that threshold should be. And then that
• 55:30
  Speaker 6: allows us further tests to really validate that this works
• 55:33
  Speaker 6: in different systems. And you know, one place where it
• 55:35
  Speaker 6: might be more challenging is actually with minerals, because minerals
• 55:38
  Speaker 6: don't uphold all of the properties of molecules. They have
• 55:41
  Speaker 6: very different structure, but they're also made out of elements
• 55:44
  Speaker 6: bonding and minerals because they have very different structure to
• 55:48
  Speaker 6: how you build up a mineral in this kind of
• 55:50
  Speaker 6: way that we do, this kind of recursive construction, and
• 55:53
  Speaker 6: what you would define as a repeat in a mineral.
• 55:55
  Speaker 6: They might have a you know, a threshold that's much
• 55:58
  Speaker 6: higher than what we observe for aqueous like our chemistry.
• 56:01
  Speaker 6: And so, as with any new theory of physics, it's
• 56:04
  Speaker 6: a process of suggesting an idea, testing it, iterating on
• 56:08
  Speaker 6: the idea, and so you know, the process of theory
• 56:10
  Speaker 6: building doesn't happen overnight. It happens over a decade or two.
• 56:13
  Speaker 6: And so these are some of the frontier questions that
• 56:15
  Speaker 6: we're asking about, Like, you know, is this actually, you know,
• 56:18
  Speaker 6: the right approach, then these things should work out, but
• 56:21
  Speaker 6: we don't know the answer yet.
• 56:22
  Speaker 5: So that's why it's exciting.
• 56:24
  Speaker 1: Sometimes life gets overwhelming, and sometimes conversations about life get overwhelming.
• 56:29
  Speaker 1: So I feel like it's time for a break. So
• 56:31
  Speaker 1: let's go ahead and hear a word from our sponsors.
• 56:46
  Speaker 2: I hope your brains are arrested and ready for some
• 56:49
  Speaker 2: more overwhelming conversation about incredible topics like the physics of life.
• 56:55
  Speaker 2: It is exciting. One question I would have in my
• 56:57
  Speaker 2: mind if I was working on this is like, whether
• 57:00
  Speaker 2: value is fifteen or nineteen or fourteen or whatever, how
• 57:02
  Speaker 2: do we know that all the information is captured by
• 57:05
  Speaker 2: this one quantity? You back it up so far with like, well,
• 57:08
  Speaker 2: we have a bunch of these examples and it seems
• 57:10
  Speaker 2: to have worked. And you're working on the theoretical underpinnings,
• 57:13
  Speaker 2: you know. I work on machine learning problems all the
• 57:16
  Speaker 2: time where we convince ourselves we've learned how to distinguish
• 57:19
  Speaker 2: between A and B because we've only seen some kind
• 57:21
  Speaker 2: of examples, and then we go off into the world
• 57:23
  Speaker 2: we're like, oops, turns out that's just one dimension of
• 57:26
  Speaker 2: a multi dimensional problem. You know. For example, if I was,
• 57:30
  Speaker 2: you know, not intelligent about this, and I said, well, look,
• 57:33
  Speaker 2: I took a bunch of examples of living things that
• 57:34
  Speaker 2: all have brown hair and non living things that don't
• 57:37
  Speaker 2: have brown hair, and then I developed my definition of
• 57:39
  Speaker 2: life to be like, does it have brown hair? I
• 57:42
  Speaker 2: could also come up with a way to distinguish between
• 57:45
  Speaker 2: quote unquote living and unliving things because my sample was
• 57:48
  Speaker 2: limited and here your sample is limited because you only
• 57:51
  Speaker 2: have examples from you know, life we've seen, and so
• 57:55
  Speaker 2: how do I know that there is a number that distinguishes.
• 57:58
  Speaker 6: So there's a couple of things, and there one of
• 58:01
  Speaker 6: them is assembly theory is not a scaler theory. So
• 58:03
  Speaker 6: it's not just about this number. It's actually about also
• 58:05
  Speaker 6: the abundance of objects at different assembly and deses.
• 58:08
  Speaker 5: So it's higher dimensional than that.
• 58:10
  Speaker 6: And the idea is you're talking about selection in this
• 58:13
  Speaker 6: massive combinatorial space, and you have to talk about the
• 58:16
  Speaker 6: reduction of the size of the space represented in the
• 58:19
  Speaker 6: objects you observe. And we have rigorous ways for thinking,
• 58:23
  Speaker 6: like based on the mathematical formalism of the theory, why
• 58:25
  Speaker 6: we're capturing the relevant features of that reduction of the
• 58:27
  Speaker 6: size of the space. People usually do do exactly what
• 58:31
  Speaker 6: you're saying, where they try to, you know, separate living
• 58:34
  Speaker 6: and non living things and then classify them. And it's
• 58:36
  Speaker 6: becoming very popular in national biology right now to do
• 58:38
  Speaker 6: machine learning on those kind of problems. I don't think
• 58:41
  Speaker 6: that that approach is generalizable. The reason I have confidence
• 58:44
  Speaker 6: in what we're doing is because there's a whole theoretical infrastructure,
• 58:47
  Speaker 6: building in a whole bunch of ideas about the nature
• 58:50
  Speaker 6: of information in life, What is causation in life? How
• 58:52
  Speaker 6: do we measure these features in molecules?
• 58:55
  Speaker 5: You know? What is it about these emergent properties of life?
• 58:57
  Speaker 3: Like I?
• 58:58
  Speaker 6: You know, I've spent my entire career basically working on
• 59:00
  Speaker 6: every kind of biological system imaginable, and Lee's lab has
• 59:03
  Speaker 6: worked on kind of every chemical system imaginable, and putting
• 59:06
  Speaker 6: all of that knowledge into one theoretical structure that we
• 59:09
  Speaker 6: can really stand behind and say, this captures the features
• 59:11
  Speaker 6: we think are important, and we can measure it, and
• 59:14
  Speaker 6: we want to test it by actually building living things
• 59:16
  Speaker 6: in the lab. So it's not ever going to be
• 59:19
  Speaker 6: convinced by just this measure and the copy number. What
• 59:22
  Speaker 6: you get convinced of is an explanatory paradigm that allows
• 59:26
  Speaker 6: you to explain not just this one data set, but
• 59:28
  Speaker 6: a whole bunch of different things. And so ultimately the
• 59:31
  Speaker 6: proof of the theory is going to come from the
• 59:32
  Speaker 6: generalizability and the new questions it allows us to answer,
• 59:36
  Speaker 6: not what we've done so.
• 59:37
  Speaker 5: Far, so't I wouldn't hang my hat on it. The
• 59:41
  Speaker 5: data we have so far.
• 59:42
  Speaker 6: But what I'm hanging my hat on is the potential
• 59:45
  Speaker 6: things that this is opening up and the way it's
• 59:47
  Speaker 6: allowing a unified explanation for a whole bunch of problems
• 59:49
  Speaker 6: in astrobiology that have traditionally been considered completely separate. And
• 59:53
  Speaker 6: also on what we talked about at the very beginning,
• 59:55
  Speaker 6: about what is physics and what does physics do? And
• 59:59
  Speaker 6: for me, it's about the explanation for the nature of
• 1:00:02
  Speaker 6: life that's more important than anyone experiment.
• 1:00:04
  Speaker 1: That feels like a nice note to end things on,
• 1:00:07
  Speaker 1: like a nice wrap up is did you have another question.
• 1:00:09
  Speaker 2: Daniel, Yeah, I would love to hear, just as a
• 1:00:13
  Speaker 2: final vision, like how you think this could, in the
• 1:00:16
  Speaker 2: best case scenario come together, like you talk in the
• 1:00:19
  Speaker 2: book about building these computers, how you like search for
• 1:00:23
  Speaker 2: the origin of life? And when I do science, I
• 1:00:26
  Speaker 2: was trying to imagine, like, what's the fantasy data I
• 1:00:28
  Speaker 2: would have? Are you hoping that we discover like alien
• 1:00:31
  Speaker 2: life here on Earth before we discover it on Enzi?
• 1:00:34
  Speaker 2: Let us would actually be your preference take us through
• 1:00:37
  Speaker 2: your scientific fantasy, right?
• 1:00:39
  Speaker 6: So my preference is that we just discover more life
• 1:00:41
  Speaker 6: and we understand what life is. So my preference is
• 1:00:44
  Speaker 6: understand what life is and have enough scientific evidence to
• 1:00:48
  Speaker 6: support that explanation. The progress of science is that's never
• 1:00:52
  Speaker 6: a single aha moment. It's like, you know, a cultural transformation.
• 1:00:55
  Speaker 6: And the way we understand a certain set of phenomena
• 1:00:57
  Speaker 6: mediated by a whole bunch of experiments and observations and
• 1:01:00
  Speaker 6: a consilience of like a whole bunch of things coming together, right,
• 1:01:03
  Speaker 6: So I think that process is highly nonlinear. For me,
• 1:01:06
  Speaker 6: the reason I really advocated more for this experimental approach
• 1:01:11
  Speaker 6: in the lab is the idea that you could iterate
• 1:01:13
  Speaker 6: between the observation and theory very quickly. So the challenge
• 1:01:17
  Speaker 6: for looking for life on alien worlds is we don't
• 1:01:20
  Speaker 6: know the prior probability for life, and we don't know
• 1:01:22
  Speaker 6: what we're looking for, and so we don't know how
• 1:01:25
  Speaker 6: many planets we have to survey before we find something,
• 1:01:27
  Speaker 6: and nor is it the case that we can actually
• 1:01:29
  Speaker 6: rule out a planet is alive or not. And so
• 1:01:32
  Speaker 6: I think by trying to bring the paradigm of looking
• 1:01:34
  Speaker 6: for alien life into an experimental paradigm, and when we
• 1:01:37
  Speaker 6: were actually building large enough chemical search engines to look
• 1:01:40
  Speaker 6: for alien life, we actually make it tractable to understand
• 1:01:43
  Speaker 6: the mechanism of the original life, the probability it doesn't happen,
• 1:01:47
  Speaker 6: and also build the theory and experiments to really test
• 1:01:50
  Speaker 6: how it does happen at the same time. So to me,
• 1:01:52
  Speaker 6: it seems the most efficient route to get actually getting
• 1:01:54
  Speaker 6: to the answer to the question. And so and you know,
• 1:01:57
  Speaker 6: part of it might be biased by my background in
• 1:01:59
  Speaker 6: cosmology and just looking at the way that particle physicists
• 1:02:02
  Speaker 6: and cosmology have collaborated to really like, you know, why
• 1:02:05
  Speaker 6: do we understand the mechanisms of like the Big Bang
• 1:02:07
  Speaker 6: so well.
• 1:02:07
  Speaker 5: It's because we build particle accelerators.
• 1:02:10
  Speaker 6: And so I think without an experimental paradigm for these
• 1:02:12
  Speaker 6: questions that really ties the planetary and the alien search
• 1:02:16
  Speaker 6: to the original life, you have to couple those problems
• 1:02:18
  Speaker 6: through the same problem at their core. And I also
• 1:02:21
  Speaker 6: just like the radical idea that like alien life will
• 1:02:23
  Speaker 6: discover it on Earth and an experiment because it's fun,
• 1:02:27
  Speaker 6: but then we'll.
• 1:02:27
  Speaker 5: Know what we're looking for, so like it seems more.
• 1:02:29
  Speaker 6: Obvious we find it elsewhere, right, So like to me,
• 1:02:32
  Speaker 6: that just seems logical, but it's also fun because you know,
• 1:02:34
  Speaker 6: like it means we can do the science really rapidly,
• 1:02:36
  Speaker 6: and I want to see it solved, so I want
• 1:02:39
  Speaker 6: the most efficient route to an answer.
• 1:02:40
  Speaker 2: And then we'll have to argue about whether it's really
• 1:02:42
  Speaker 2: alien if it was on Earth Nater.
• 1:02:44
  Speaker 6: Right, that's a good problem to have, right, because I think, yeah,
• 1:02:48
  Speaker 6: a really good problem to have.
• 1:02:49
  Speaker 3: Come full circle to good beer conversation.
• 1:02:51
  Speaker 5: Yes, yes, there you go.
• 1:02:53
  Speaker 6: See if you answer one of the beer questions, but
• 1:02:55
  Speaker 6: you have a better beer question, it's not a problem
• 1:02:57
  Speaker 6: you yep.
• 1:02:59
  Speaker 2: Well, thank you much for coming on and talk to
• 1:03:01
  Speaker 2: us about assembly theory and for giving us an advanced
• 1:03:04
  Speaker 2: peak at your book. Everyone, it's called Life As No
• 1:03:07
  Speaker 2: One Knows It, The physics of Life's emergence. Congratulations on
• 1:03:11
  Speaker 2: the book and best of luck.
• 1:03:12
  Speaker 5: Thank you so much, Thank you both.
• 1:03:15
  Speaker 3: Yeah, thank you all.
• 1:03:17
  Speaker 2: Right, And that was our conversation with Sarah and Marie Walker,
• 1:03:19
  Speaker 2: author of the recent book Life As No One Knows It,
• 1:03:22
  Speaker 2: which you can now pick up at all fine booksellers. Kelly,
• 1:03:26
  Speaker 2: what's your takeaway? Is physics going to help us understand
• 1:03:28
  Speaker 2: what life is?
• 1:03:29
  Speaker 1: Well, you know, my takeaway is pretty similar to my
• 1:03:33
  Speaker 1: takeaway many years ago when I was arguing with my
• 1:03:35
  Speaker 1: fellow grad students, which is, Wow, this is complicated, which
• 1:03:39
  Speaker 1: is pretty much the conclusion to every ecology paper you'll
• 1:03:42
  Speaker 1: ever read is it's complicated and it depends and anyway,
• 1:03:46
  Speaker 1: So yeah, it's complicated.
• 1:03:48
  Speaker 3: What do you think.
• 1:03:49
  Speaker 2: I think it's a valiant effort and it's worth doing,
• 1:03:52
  Speaker 2: and we're going to learn things along the way. I
• 1:03:55
  Speaker 2: don't know that we're going to figure it out. I
• 1:03:57
  Speaker 2: don't know this is the right approach, but I think
• 1:04:00
  Speaker 2: thinking hard about it is the first step to figuring
• 1:04:02
  Speaker 2: it out. No matter where it goes. Often you go
• 1:04:05
  Speaker 2: down to the root of something and you discover something
• 1:04:07
  Speaker 2: completely different than solving the problem you meant to, or
• 1:04:11
  Speaker 2: you make breakthroughs in other areas. So I'm excited to
• 1:04:14
  Speaker 2: see where this goes. I'm excited that people are thinking
• 1:04:17
  Speaker 2: about these problems. I think it helps clear away some
• 1:04:20
  Speaker 2: of the cobwebs and provides a little bit of clarity.
• 1:04:22
  Speaker 2: But I guess I have to put it into like
• 1:04:24
  Speaker 2: we'll see category before I'm actually convinced that this is
• 1:04:27
  Speaker 2: the right way to think about life.
• 1:04:29
  Speaker 1: I mean, it would be pretty epic if like on
• 1:04:32
  Speaker 1: demand new life could be created in the lab and
• 1:04:34
  Speaker 1: we could look at different evolutionary trajectories and stuff like that.
• 1:04:37
  Speaker 1: I mean, the evolutionary biologist would go wild if that
• 1:04:39
  Speaker 1: could be accomplished. I don't know where you start to
• 1:04:42
  Speaker 1: do something like that, but it would be pretty exciting
• 1:04:45
  Speaker 1: if it could be accomplished.
• 1:04:46
  Speaker 2: Yeah. And then, of course, the next philosophical question would be,
• 1:04:49
  Speaker 2: if you've created a new kind of living goo in
• 1:04:52
  Speaker 2: your lab, is it an alien or is it just
• 1:04:55
  Speaker 2: another kind of earthling?
• 1:04:56
  Speaker 1: And how long before it begins to eat human flesh?
• 1:05:01
  Speaker 2: Day one? I'm hoping. I mean, if this movie's going
• 1:05:03
  Speaker 2: to be any.
• 1:05:04
  Speaker 3: Good, right, you know it's gonna happen fast.
• 1:05:07
  Speaker 4: Yeah.
• 1:05:08
  Speaker 2: I mean you could also flip the question around and like,
• 1:05:10
  Speaker 2: say that new kind of living goo becomes intelligent, how
• 1:05:13
  Speaker 2: do we know it doesn't call us aliens? Right? And
• 1:05:15
  Speaker 2: like we're at home, how can we be aliens?
• 1:05:17
  Speaker 1: That's right, that's right, let's all just get along and
• 1:05:20
  Speaker 1: be earth right.
• 1:05:22
  Speaker 2: That sounds good exactly. I look forward to a big,
• 1:05:25
  Speaker 2: cozy family meal, passing the bread and the corn cobs
• 1:05:28
  Speaker 2: around with our fellow earth goo.
• 1:05:30
  Speaker 1: I'm going to schedule it one week after our meeting,
• 1:05:33
  Speaker 1: where you tell me about how physics has solved all
• 1:05:35
  Speaker 1: the problems of the world.
• 1:05:36
  Speaker 2: Sounds good, and I'll bring some towels.
• 1:05:38
  Speaker 3: That's good because I'll forget mine.
• 1:05:40
  Speaker 2: Bring extra please, Katrina will have an extra one in
• 1:05:43
  Speaker 2: her bag. No worries, all right. Thanks everyone for joining
• 1:05:46
  Speaker 2: us on this squishy discussion about the physics of life.
• 1:05:49
  Speaker 2: Hope you learned something I certainly did. And thank you
• 1:05:51
  Speaker 2: very much Kelly, my friend and co host, for joining
• 1:05:54
  Speaker 2: me on today's.
• 1:05:55
  Speaker 1: Episode My Pleasure.
• 1:05:57
  Speaker 3: Thanks Daniel.
• 1:05:59
  Speaker 2: Tune in next time time For more science and curiosity.
• 1:06:06
  Speaker 2: Come find us on social media, where we answer questions
• 1:06:09
  Speaker 2: and post videos. We're on Twitter, Discorg, Insta, and now TikTok.
• 1:06:14
  Speaker 2: Thanks for listening, and remember that Daniel and Jorge Explain
• 1:06:17
  Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
• 1:06:21
  Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
• 1:06:26
  Speaker 2: you listen to your favorite shows.