Sara Walker: The Origin of Life on Earth and Alien Worlds | Lex Fridman Podcast #198

the following is a conversation with sarah walker a nestor biologist and theoretical physicist at arizona state university and the santa fe institute she's interested in the origin of life how to find life on other worlds and in general the more fundamental question of what even life is she seeks to discover the universal laws that describe living systems on earth and elsewhere using physics biology and computation quick mention of our sponsors athletic greens netsuite blinkist and magic spoon check them out in the description to support this podcast as a side note let me say that my hope for this podcast is to try and alternate between technical and non-technical discussions to jump from the big picture down to specific detailed research and back to the big picture and to do so with scientists and non-scientists long term i hope to alternate between discussions of cutting-edge research in ai physics biology to topics of music sport and history and then back to ai ai is home i hope you come along with me for that wild oscillating journey some people message me saying to slow down since they're falling behind on the episodes of this podcast to their disappointment i have to say that i'll probably do more episodes not less but you really don't need to listen to every episode just listen to the ones that spark your curiosity think about it like a party full of strangers you don't have to talk to everyone just walk over to the ones who look interesting and get to know them and if you're lucky that one conversation with a stranger might change the direction of your life and it's a short life so be picky with the strangers you talk to at this metaphorical party this is the lex friedman podcast and here is my conversation with sarah walker how did life originate on earth what are the various hypotheses for how life originated on earth yeah so i guess you're asking a historical question which is always a good place to start thinking about life um so there's a lot of ideas about how life started on earth um probably the most popular is what's called the rna world scenario um so this idea is probably the one that you'll see most reported in the news and is based on the idea that there are um molecules in our bodies um that uh relay genetic information and we know those as dna obviously but there's also sort of an intermediary called rna ribonucleic acid that also plays the role of proteins and people came up with this idea in the 80s that maybe that was the first genetic material because it could play both roles of being genetic and performing catalysis and then somehow that idea got reduced to this idea that there was a molecule that emerged on early earth and underwent darwinian evolution and that was the start of life so there's a lot of assumptions packed in there that we could unpack but that's sort of the leading hypothesis there's also other ideas about life starting as metabolism and so that's more connected to the geochemistry of early earth and it would be kind of more focused on this idea that you get some kind of catalytic cycle of molecules that can reproduce themselves and form some kind of metabolism and then life starts basically as self-organization and then you have to explain how evolution comes later right so that's the difference between sort of uh energy and genetic code so like energy and information are those are the two kind of yeah yeah i think that's a good way of putting that it's um it's kind of funny because i think most of the people that think about these things are really disciplinary bias so the people that tend to think about genetics come from a biology background and they're really evolution focused and so they're worried about where does the information come from and how does it change over time but they're talking about information in a really narrow way where they're talking about a genetic sequence and then most of people that think about metabolism origins of life scenarios tend to be people like physicists or geochemists that are worried about what are the energy sources and what you know like what kinds of organization can you get out of those energy sources okay so which one is your favorite i don't like either okay all right can we talk about them for a little bit longer though uh so okay so there's uh early earth what was that like was there just mostly covered by oceans was there heat sources energy sources so if we uh talk about the metabolism view of the origin of life like where was the source of energy probably the most popular view for where the original life happened on earth is hydrothermal vents because they had sufficient energy and so we don't really know a lot about early earth we have you know some ideas about when oceans first formed and things like that but the time of the original life is kind of um not well understood or pinned down and the conditions on earth at that time are not well known but a lot of people do think that there was probably hydrothermal vents which are really hot chemically active regions say on the sea floor in modern times which also would have been present on early earth and they would have provided energy and organics and basically all of the right conditions for the origins of life which is one of the reasons that we look for these hydrothermal systems when we're talking about life elsewhere too okay and for the genetic code the idea is that the rna is the first like why would rna be the first moment you can say it's life i guess the idea is it could both have persistent information and then it can also do some of the work of like what creating a self-sustaining organism yeah that's the basic idea so the idea is you have in an rna molecule you have a sequence of characters say so you can treat it like a string in a computer and it can be copied so information can be propagated which is important for evolution because evolution happens by having inheritance of information so for example you know like my eyes are brown because my mother's eyes were brown so you need that copying of information but then you also have the ability to perform catalysis which means that that rna molecule is not inert in that environment but it actually interacts with something that could potentially mediate say a metabolism that could then fuel the actual reproduction of that molecule so in some ways people think that rna gives you you know the most bang for your buck in a single molecule and therefore you know it gives you all the features that you might think are life um and so that this is sort of where this rna world conjecture came from is because of those two properties isn't it amazing that rna came to be in general isn't it yes that is amazing okay so we're not talking down about rna no no i love rna it's one of my favorite molecules i think it's beautiful it's just not step one yeah i think i think the issue it's not even the rna world is a problem and actually if you really um dig into it the rna world is not one hypothesis it is a set of hypothesis hypotheses sorry and they range from a molecule of rna spontaneously emerged on the early earth and started evolving which is kind of like the hardest rna world scenario which is the one i cited and i get a little um uh animated about because it seems so blatantly wrong to me but that's a separate story and then the other one is actually something i agree with which is that you can say there was an rna world because rna was the first genetic material for life on earth so an rna world could just be the earliest organisms that had genetics in a modern sense didn't have dna evolved yet they had rna right and so that's sort of a softer rna world scenario in the sense that it doesn't mean it was the first thing that happened but it was a thing that definitely was part of the lineage of events that led to us so if life was a like a best of album it would be on the maybe one of the songs on there yes one of the early songs okay it's on the greatest hits greatest hits that's the word i was looking for okay did life do you think originate once twice three times on earth multiple times what do you think i think that's a really difficult question um and an important question it's a super important question no that no it's a really important question um and so there there's some so there's there's a lot of questions in that question um so one of the first ones that i think needs to be addressed is is the original life a continuous process on our planet so we think about the original life is something that happened on earth um say almost four billion years ago because we have evidence of life emerging very early on our planet um and then an original life event quote unquote a singular event whatever that was happened and then all life on earth that we know is a descendant of that particular event in our universe right and so um but uh we don't have um any idea one way or the other if the original life is happening repeatedly and maybe it's just not taking off because life is already established that's a argument that people will make or maybe there are alternative forms of life on earth that we don't even recognize um so this is the idea of a shadow biosphere that there actually might just be completely other life on earth but it's so alien that we don't even know what it is i'm gonna have to talk to you about the shadow biosphere in a second but first let me ask for the other alternative which is panspermia right so that's the idea the hypothesis that life exists elsewhere in the universe and got to us through like an asteroid or a planetoid or some uh according to wikipedia space dust whatever the heck that is uh it sounds fun but basically rode along yeah whatever kind of rock and got to us do you think that's at all a possibility sure so i think the reason that most original life scientists are interested in the origin of life on earth and say not the original life um you know on mars and then panspermia you know the exchange of life between planets being the explanation is once you start removing the original life from earth you know even less about it than you do if you study it on earth although i think there are ways of reformulating the problem this is why i said earlier like oh you mean the historical original life problem you don't mean the problem of how does life arise in the universe and what the universal principles are because there's this historic problem how did it happen on early earth and there's a more tractable general problem of how does it happen and how does it happen is something we can actually ask in the lab how does it how did it how did it happen on early earth is a much more detailed and nuanced question and requires detailed knowledge of what was happening on early earth that we don't have and i'm personally more interested in general mechanisms so to me it doesn't matter if it happened on earth or it happened on mars it just matters that it happened we have evidence that happened the question is did it happen more than once in our universe and so the reason i don't find panspermia as a particularly i think it's a fascinating um hypothesis i definitely think it's possible um and um and i in particular i think it's possible once you get to the stage of a life where you have technology because then you you obviously can spread out into the cosmos um but it's also possible for microbes because we know that um certain microorganisms can survive the journey in space and we you know they can live in a rock and go between mars and earth like people have done experiments to try to prove that could work um so in that scenario it's super cool because then you get planetary exchange but say we go find we go look for life on mars and it ends up being exactly the same life we have on earth biochemically speaking then we haven't really discovered something new about the universe what kind of aliens are possible were there other original life events if we find if all the life we ever find is the same original life event in the universe it doesn't help me solve my problem but it's possible that that would be a sign that you could separate the environment from the basic ingredients yes so that's true you can have like a life gun that you shoot throughout the universe and then uh like once you shoot it it's like the simpsons with a makeup gun that was a great episode uh when you shoot this life gun it'll he'll find the earth's it'll like get sticky it'll stick to the earth's and that kind of reduces the barrier of uh like the time it takes the the luck it takes to actually from nothing from the basic chemistry from the basic physics the universe for the life to spring up yeah i think this is actually super important to just think about like does life getting seated on a planet have to be geochemically compatible with that planet so you're suggesting like we could just shoot guns in space and like life could go to mars and then it would just live there and be happy there um but that's actually an open question so one of the things i was going to say in response to your question about whether the original life happened once or multiple times is for me personally right now in my thinking although this changes on a weekly basis but um is that i think of life more as a planetary phenomena so i think the original life because um because life is so um intimately tied to planetary cycles and planetary processes and this goes all the way back through the history of our planet that the original life itself grew out of geochemistry and became coupled and controlled geochemistry and and when we start to talk about life existing on the planet is when we have evidence of life actually influencing properties of the planet um and so so if life is a planetary property um then going to mars is not a trivial thing because you basically have to make ours mars more earth-like um and so in some sense um like when i think about sort of long-term vision of humans in space for example really what you're talking about when you're saying let's send our civilization to mars is you're not saying let's send our civilization to mars you're saying let's reproduce our planet on mars like the information from our planet actually has to go to mars and make mars more earth-like which means that you're now having a reproduction process like a cell reproduces itself to propagate information in the future planets have to figure out how to reproduce their conditions including geochemical conditions on other planets in order to actually reproduce life in the universe which is kind of a little bit radical but i think for long-term sustainability of life on a planet that's absolutely essential okay so if we were to think about life as a planetary phenomenon and so life on mars would be best if it's way different than life on earth we have to ask the very basic question of what is life i actually don't think that's the right question to ask it took me a long time to get there right so cross it out yeah you cross it off your list it's wrong no question um no no no i mean i think it has an answer but i think the part of the problem is um you know most of the places in science where we get really stuck is because we don't know what questions to ask um and so you can't answer a question if you're asking the wrong question um and i think uh the way i think about it is obviously i'm interested in what life is so i'm being a little cheeky when i say that's the wrong question to ask that's exactly like the question that's like the core of my existence but um but i think the way of framing that is what is it about our universe that allows features that we associate life to be there um and so really what i guess when i'm asking that question what i'm after is an explanatory framework for what life is right and so most people they try to go in and define life and they say well life is uh say a self-reproducing chemical system capable of darwinian evolution that's a very popular definition for life um or life is something that metabolizes and eats that is not how i think about life what i think about life is there are principles and laws that govern our universe that we don't understand yet that have something to do with how information interacts with the physical world i don't know exactly what i mean even when i say that um because we don't know these rules um but it's a little bit like um i like to use analogies you'll give me time to be like a little long-winded for a second even in as i um but um but sort of like if you look at the history of physics for example this is like so we are in the period of the development of thought on our planet where we don't understand what we are yet right um there was a period of thought in the history of our planet where we didn't understand what gravity was um and we didn't understand for example that planets in the heavens you know were actually planets or that they operated by the same laws that we did um and so there has been this sort of progression of getting a deeper understanding of explaining basic phenomena like i'm not gonna drop the cup i'll drop the water bottle there you go okay that fell right but why did that fall um this is why i'm a theorist not an experiment i could have gone wrong in so many ways i know i could have especially if i did the confidence smash anyway um so um so if you think you take this view that there's sort of some missing principles i associate them uh to information and what it what the sort of feeling there is there's some missing explanatory framework for how our universe works and if we understood that physics it would explain what we are um it might also explain a lot of other features we don't associate to life um and so it's a little like um people accept the fact that gravity is a universal phenomena but when we want to study gravity we study things like large scale you know galactic structures or black holes or planets if we want to understand information and how it operates in the physical world we study intelligent systems or living systems because they are the manifestation of that physics and the fact that we can't see that clearly yet or we don't have that explanatory framework i think it's just because we haven't been thinking about the problem deeply enough but i feel like if you're explaining something you're deriving it from some more fundamental property and of course um i have to say i'm wearing my my physicist hat so i have a huge bias of liking simple elegant explanations of the universe that um you know really are compelling but i think one of the things that i've sort of maybe in some ways rejected my training as a physicist is that most of the elegant explanations that we have so far don't include us in the universe and i can't help but think there's something really special about what we are and there have to be some deep principles at play there um and so so that's sort of my perspective on it now when you ask me what life is i have some ideas of what i think it is but i think that we haven't gotten there yet because we haven't been able to see that structure and it's and just go back to the gravity example it's a little like you know in ancient times they didn't know i was talking about stars and heavens and things they didn't know those were um you know governed by the same principles as that starting to experiment here's where i was going with it once you realize like newton did that you know heavenly emotions and earthly emotions are governed by the same principles and you unify terrestrial and celestial motion you get these more powerful ideas um and i i think where life is is somehow unifying these abstract ideas of computation and information with the physical world with matter and realizing that there's some explanatory framework that's not physics and it's not computation but it's something that's deeper so answering the question of what is life requires deeply understanding something about the universe as information processing universe is computation something about like would uh once you come up with an answer to what is life well the words information and computation be in the paragraph no i don't think so oh damn it okay i know it doesn't help does it i know i i hate actually i hate this about what i do because it's so hard to communicate right with words like when you have words that are um ideas that have historically described one thing and you're trying to describe something people haven't seen yet right and the words just don't fit so what uh what's wrong is it too ambiguous the word information we could switch to binary if you want yeah no i don't think it's binary either i think information is just loaded i use it so the other way i might talk about it is the physics of causation but i think that's worse because causation is even more loaded word than um information causation is fundamental you think i do yeah and um in some sense i think the physics so this is the really radical part some sense like when i really think about it sort of most deeply uh what i think life is is actually the physics of existence what gets to exist and why um and you know for simple elementary particles that's not very complicated because the interactions are simple but for things like um you know you and me and human civilizations um you know what comes next in the universe is really dependent on what came before and there's a huge space of possibilities of things that can exist and when i say information and causation what i mean is why is it that cups evolved in the universe and not some other object that could deliver water and not spill it i don't know what you would call it uh maybe it wouldn't be a cup but um but it's a huge it it's um you know you know people talk about the space of things that could exist as being actually infinitely large right i don't know if i believe in infinity um but i do think that there is something very interesting about the problem of what exists in its relationship to life so do you think this the set of things that could exist is finite it's very large but like if we were to think about the physics of existence like how how many shapes of mugs can there be like is uh in the initial programming i should go to the math department for that but so that's not a topology question i just mean maybe another way to ask is what do you think is fundamental to the universe and what is emergent so if existence i was supposed to think of that as somehow fundamental you think so there's a couple problems in physics that i think this is related to one is why does mathematics work at describing reality so well um and then there is this problem of we don't understand why the laws of physics are the way they are or why certain things get to exist or what put in place the initial condition of our universe right there's all of these sort of really deep and big problems and they they all um indirectly are related i think to the same kind of thing that um you know our physics is really good if you specify the initial condition at specifying a certain sequence of events but it doesn't deal with the fact that other things could have happened which is kind of an informational property like a counter factual property um and it's not good at explaining uh you know this conversation right now it's just it there are certain things that are outside the explanatory reach of current physics and um i think they require looking at it from a completely different direction um and so i don't want to have to fine-tune the initial condition of the universe to specify precisely all the information in this conversation i think that's a ridiculous assertion um but that's sort of like how people want to frame it when they talk about um you know the standard model is sufficient if we had computing power to basically explain all life in our existence an interesting thing you said is the way we think about information computation is by observing a particular kind of systems on earth that exhibit something we think of as intelligence but that's that's like uh looking at i guess the tip of an iceberg and we should be really looking at the fundamentals of like the iceberg like like like what makes water and ice and and and the chemistry that from which intelligence emerges essentially we can't just couple the information from the physics and i think that's what we've gotten really good at doing especially with sort of the modern age where you know software is so abstracted um from hardware but the entire process of biological evolution has basically been built like been building layers of increasing abstraction and so it's really hard to see that physics in us but it's much clearer to see it in molecules yeah but i guess i'm trying to figure out what what do you think are the best tools to look at it what do you think an open mind is that a tool what's the physics of an open mind i think if we saw that we'll solve everything i'm saying an open mind because i think the biggest stumbling block um to understanding sort of the things i've been trying to articulate or and when i talk also with colleagues that are thinking deeply about these same issues is none of it is inconsistent with what we know it's just such a radically different perception perception of the way we understand things now that it's hard for people to get there and in some ways you have to almost forget what you've learned in order to learn something new right so i feel like most of my career trying to understand the problem of life has been variously forgetting and then relearning things that i learned in physics and and i think you have to you have to have a capacity to learn things but then accept that things that you were you you learned might not be true um or or might need refinement or reframing um and the best way i can say that is just like with a physics education there are just certain things you're told in undergrad that are like facts about the world and your physics professors never tell you that those facts actually emerge from a human mind right so we're taught to think about say the laws of physics for example as this like autonomous thing that exists outside of our universe and tells our universe how it works yeah um but the laws of physics were invented by human minds to describe things that are regularities in our everyday experience right they don't exist autonomous to the universe right so it's like turtles on top of turtles but eventually gets the human mind and then you have to explain the human mind with the turtles yes so you have to yeah it comes from humans this understanding the simplification of the universe these models yeah there's a guy named stephen wolfram there's a concept called cellular automata so there's a there's some mysteries in these um systems that are computational in nature that have maybe echoes of the kind of mysteries we should need to solve to understand what is life so if we could talk take a computational view of things do you think there's something compelling to reducing everything down to computation like the universe is computation and then trying to understand life so throw away the biology throw away the chemistry throw away even the physics that you you learn undergrad in graduate school and more look at these simple little systems whether it's cellular automata or whatever the heck kind of computational systems that operate on simple local rules and then create complexity as they evolve is is it uh at all do you think productive to focus on those kinds of systems to get an inkling of what is life and if it is do you do you think it's it's possible to come up with some kind of laws and principles about what makes life in those computational systems so i like cellular automata i think they're good toy models um but mostly like where i've thought about them and use them is to actually um let's say poke at sort of the current conceptual framework that we have and see where the flaws are um so i think like the part that you're talking about that people find intriguing is that if you have like a fairly simple rule and you specify some initial condition and you run that rule and that initial condition you could get really complex patterns emerging and ooh doesn't that look lifelike um yeah well it's like really surprising isn't it it is really surprising and they're beautiful um and i i think they have a lot of nice features associated to them um i think the things that i find yeah so so i i do think um as a proof of principle that you can get complex things emerging from simple rules they're great um as a sort of proof of principle about some of the ways that we might think of computation as being sort of a fundamental principle for dynamical systems and maybe the the evolution of the universe as a whole they're a great model system as an explanatory framework for life i think they're a bit problematic for the same reason that the laws of physics are a bit problematic um and the clearest way i can articulate that is like cellular automata are actually cast in sort of a conceptual framework for how the universe should be described that goes all the way back to newton in fact with this idea that we can have a fixed law of motion which exists sort of it's given to you you know the great programmer in the sky gave you this equation or this rule and then you just run with it um and the rule doesn't have so a good feature of the rule is it doesn't have specified in the rule information about the patterns it generates so you wouldn't want for example the my cup or my water bottle or you know me sitting here to be specified in the laws of physics that would be ridiculous because it wouldn't be a very simple explanation of all things happening i'd have to explain everything so and tell your time to have that feature and the laws of physics have that feature um but but you know you also need to specify the initial condition um and it also it basically means that everything that happens is sort of a consequence of that initial condition and i think this kind of framework is just not the right one for biology um and part of the way that it's easiest to see this is um a lot of people talk about self-reference being important in life the fact that um you know like the genome has information encoded in it that information gets read out um it specifies something about the architecture of a cell the architecture of the cell includes the genome so the genome has basically self-referential information self-reference obviously comes up in computational law because it's kind of foundational um to turing's work and what girdle did with the incompleteness theorems and things so there's a lot of parallels there and and people have talked about that at depth um but the other way of kind of thinking about it in terms of like a more physics-y way of talking about it is that what it looks like in biology is that the rules or the laws depend on the state this is typical in computer science this is obvious to you you know the update rule depends on the state of the machine right but and you know you don't think about um uh you know that being sort of the dynamic and physics it's you know the rules given to you and then it you know it's a it's a very special subclass say of computations if you know you don't ever change the update um but in biology it seems to be that the state and the law change together as a function of time and we don't have that as a paradigm in physics and so a lot of people talked about this as being kind of a perplexing feature that maybe there are certain scenarios where the laws of physics or the laws that govern a particular system actually change as a function of state of that system that's trippy so yeah the the hope of physics it's a hope i guess but often stated as a underlying assumption is that the law is uh static right okay and even having laws that vary in time and not even as a function of the state is very radical when you the time in general like yeah you want to remove time from the equation as much as possible yeah i i do um there's some interesting things in this like when we think it's sort of deep more deeply about the actual physics that we're trying to propose governs life um with me with collaborators and then also other people that think about similar things that time might actually be fundamental and there really is an ordering to time um and that events in the universe are unique because they have a particular you know they they happen like an object in the universe requires a certain history of events in order to exist which therefore suggests that time really does have an ordering i'm not talking about the flow of time and our perception of time just the ordering of events causation yes causation there's that word again so causation that's when you say time you mean causation yes in your proposed model of the physics of life the the fundamental thing would be causation if you were to bet your money on on one particular horse or whatever yes and then space is emergent yes so everything's emergent except time kind of yeah or causation change all the time why it look like laws are the same laws well because uh well one way um and i actually this idea comes from lee cronin because i work with him very closely on these things is that the laws of physics look the way they do because they're low memory laws so they don't require a lot of information to specify them they're very easy for the universe to implement but if you get something like me for example i require 4 billion year history to exist in the universe i come with a lot of historical baggage and that's part of what i am as a set of causes that exist in the universe so i have local rules that apply to me that are associated with sort of the information in my history that aren't universal to every object in the universe and there are some things that are very easily easy to implement low memory rules that apply to everything in the universe so there's no shortcuts to you no i so yeah i don't believe in like things like boltzmann brains or uh you know fluctuations out of the vacuum that can produce things like your desk ornaments i actually think they require a particular causal chain of events to exist well i appreciate the togetherness of that but uh so how does that if we have to simulate the entire universe to create the ornaments and the two of us how are we supposed to create engineer life yeah that's not this goes back to sort of the critique of the rna world i think one of the problems and i'll get to answering your question but i think this is kind of relevant here one of the problems with the rna world when we test it in the laboratory is how much information we're putting into the experiment we specify the flasks we make pure reagents we mix them we take them out we put them in the next flask we change the ph we change the uv light and then we get a molecule and it's not even an rna molecule necessarily it might just be a base right um and so people don't usually think about the fact that we're agents in the universe making that experiment and therefore we put a little bit of life into that experiment um because it's part of our biological lineage in the same sense that a couple or i am a part of the biological lineage the experimental ideas are injecting life yes and the constraints that we put on the experiments because those conditions wouldn't exist in the universe on planet earth at that time without us as the boundary condition right so even though we're not actually adding any actual like chemistry or biology that it could be identified as life are the constraints we're adding to the experiment the design of the experiment yeah you can think of a design experiment as a program you put information in it's an algorithmic procedure that you design the experiment and so um so the original life problem becomes one of minimizing the information we put into physics to actually watch the spontaneous original life can we can we have so can is it possible in the lab to have an information vacuum then so like if we could we would that would be amazing i don't know that's a good question for more for lee yeah you guys by the way for people who don't know lee cronin is uh you guys are uh colleagues and uh i've gotten a chance to listen to the two of you talking there's great sort of chemistry and you're brilliant brainstorming together and there's there's a really exciting community here of of brilliant people from different disciplines working on the problem yeah of life of complexity of uh i don't know whatever the words fail us to describe the exact problem we're trying to actually understand here intelligence all those kinds of things okay so what what uh from a lab perspective so lee i guess would you call him a chemist no i think by training he's a chemist but i think most of the people that work in the field we do have lost their discipline that's why i couldn't answer your question okay i don't know what you call them yeah i don't know what i call myself i don't know what i call any of my friends so why why is it so hard to create uh and it's an interesting question to create biological life in the lab like from your perspective is that an important problem to work on to try to recreate the historical origin of life on earth or echoes of the historical origin i think echoes is more appropriate i don't think asking the question of what was the exact historical sequence of events and engineering every step in the process to make exactly the chemistry of life on earth as we know it is a meaningful way of asking the question and it's a little bit like um you know if since you're in computer science like if you know the answer to a problem it's all it's easier to find a program to specify the output right but if you don't know the answer or priority you know finding an algorithm for like say finding a prime or something it's easy to um you know uh verify it's a prime number it's hard to find the next prime um and uh the way the original life is structured right now in the historical problem is you know the answer and you're trying to retrodict it by breaking it down into the set of procedures where you're putting a lot of information in and what we need to do is ask the question of how is it that the rules of how our universe is structured permits things like life to exist and what is the phenomena of life and those questions are obviously essentially the same question and so you're looking essentially for this missing physics this missing explanation for what we are and you need to set up proper experiments that are going to allow you to probe the vast complexity of chemistry in an unconstrained way with as little information put in as possible to see when things when does information actually emerge how does it emerge what is it and part of the the sort of conjecture we have is that this physics only becomes relevant or at least this is this is my personal conjecture and um and it's sort of uh validated by this kind of theory experiment collaboration um that we we have working in this area um that this you know sort of i made the point about like gravity existing everywhere right but when you study um an atomic nucleus you don't care about gravity it's not relevant physics there right it's it's weak it doesn't matter and so this idea that that there's kind of a physics associated with information for me it's very evident that that physics doesn't become relevant until you need information to specify the existence of a particular object and the scale of reality where that happens is in chemistry because of the combinatorial diversity of chemical objects that can exist far outs exceeds the amount of resources in our universe so if you want to you can't make every possible protein of length um you know 200 amino acids there's not enough resources so in order for this particular protein to exist and this protein to exist in high abundance means that you have to have a system that has knowledge of the existence of that protein and can build it so existence comes to be at the chemical level so existence is most uh is uh best understood at the chemical level it's most evident it's a little bit like nobody argues that gravity doesn't exist in an atomic nucleus it's just not relevant physics there so the physics of information is everywhere it exists at every combinatorial scale but it becomes more and more relevant the more set of possibilities that could exist because you're you're you're you have to specify more and more about why this thing exists and not the infinite it's not an infinite set but you know the set of undefined set of other things that could exist so can ask a weird yeah question which is so let's look into the future i try that every day it never works so say a nobel prize is given in physics maybe chemistry for discovering the origin of life no not but not the historical origin some kind of thing that we're talking about what exactly would what do you think that like what do you think that person maybe you did to get that nobel prize like what would they have to have done because you could do a bunch of experiments that go like with an aha moment like you rarely get the nobel prize for like you've solved everything we're done right it's like some inkling of some deep truth right like what do you think that would actually look like would it be an experimental result uh i mean it will have to have some kind of experimental maybe validation component so what would that look like this is an excellent question i want to sorry i'm going to make a quick point which is just a slight tangent but you know like when people ask about the origin of mass you know and like looking for the higgs mechanism and things they never like we need to find the historical origins of life in the early unit although those things are related right so um so this problem of origins of life in the lab i think is really important but the the higgs is a good example because you had theory to guide it so somehow you need to have an explanatory framework that can say that we should be looking for these features and explain why they might be there and then be able to do the experiment and demonstrate that it matches with the theory but it has to be something that is outside sort of the paradigm of what we might expect based on what we know right so this is a really sort of tall order um and i think um i mean i i guess the way people would think about it is like you know if you had a bacteria that climbed out of your test tube or something and it was like you know moving around on the surface that would be ultimate validation you saw the original life in an experiment but i don't think that's quite what we're looking for i think what what we're looking for is evidence of when information that originated within the bounds of your experiment and you can demonstratively prove emerge spontaneously in your experiment wasn't put in by you actually started to govern the future dynamics of that system and specify it and you could somehow relate those two features directly so you know that the program specifying what's happening in that system is actually internal to that system like say you have a chemical thing in a box well so that's that's one nobel prize with the experiment which is like information in some fundamental way originated within the constraints of the system without you injecting anything but another experiment is you injected something yeah and got out information yes so like you injected i don't know like uh like some sugar and like something something that doesn't necessarily feel like it should be information yeah so i actually no i mean sugar is information right so part of the argument here is that every physical object is well it's information but it's a set of causal histories and also a set of possible futures so there's an experiment um that i've talked a lot about uh with lee cronin but also with michael lockman and chris kempies who are at santa fe about this idea that sometimes we talk about is like seating assembly um which is you take a high high complexity like a an object that exists in the universe because of a long causal history and you seed it into a system of lower causal history and then suddenly you see all of this complexity being generated so i think another validation of the physics would be say you engineer an organism by by purposefully introducing something where you understand the relationship between the causal history of the organism and the say very complex chemical set of ingredients you're adding to it and then you can predict the future evolution of that system to some statistical uh set of constraints and possibilities for what it will look like in the future you know i'm a physical structure obviously like i i'm composed of atoms the configuration of them and the fact that they happen to be me is because i'm not actually my atoms i am a informational pattern that keeps re-patterning those atoms into sarah um and i have also associated to me is like a space of possible things that could exist that i can help mediate come into existence because of the information in my history and so when you understand sort of that time is a real thing embedded in a physical object then it becomes possible to talk about how histories when they interact and history is not a unique thing it's a set of possibilities when they interact how do they specify what's coming next and then where does the novelty come from in that structure because some of it is kind of things that haven't existed in the past can exist in the future let me ask about this entity that you call sarah yes i talk to myself about myself in third person sometimes i don't know why uh so maybe this is a good time to bring up consciousness sure it's been here all along wow has it so what i mean at least in this conversation i think i've been conscious most of it but maybe i haven't well yeah speak so speak for yourself you're you're you're projecting your consciences onto me you don't know if i'm conscious or not is it um you're right is that uh he talked about the physics of existence he talked about the emergence of um of causality uh sorry you talked about causality and time being fundamental to the universe does consciousness fit into all of this like uh do you draw any kind of inspiration or value with the idea of pan psychism that maybe one of the things that we ought to understand is the physics of consciousness like one of the missing pieces in the physics view of the world is understanding the physics of consciousness or like that word has so many concepts underneath it but let's put it let's put consciousness as a label on a black box of mystery that we don't understand do you think that black box holds the key to uh finally answering the question of the physics of life the problems are absolutely related i think um most and i'm interested in both because i'm just interested in what we are and to me the most interesting feature of what we are is our minds and the way they interact with other minds like minds are the most beautiful thing that exists in the universe so how did they come to be i'm sorry to interrupt so when you say we you mean humans i mean humans right now but i but that's because i'm a human i think i am you think there's something special to this particular no no no um no um i don't i'm not a human-centric thinker but are you one entity you said a bunch of stuff came together to make a sarah like yourself as one entity are you just a bunch of different components like is there any value to understand the physics of sarah like or are you just a bunch of different things that are like a nice little temporary side effect yeah you could think of me as a bundle of information that just became temporarily aggregated or individual yeah that's fine i agree with that view um okay i think that is a compliment actually but you you've but nevertheless that bundle of information has become conscious or at least keeps calling her self-conscious yeah i think i'm conscious right now but i might not be but that's okay um or you wouldn't know um so yeah so this is the problem so yeah usually people when they're talking about consciousness are worried about the subjective experience and so i think that's why you're saying i don't know if you're conscious because i don't know if you're experiencing this conversation right now um and nor do you know if i'm experienced in the conversation right now and so this is why this is called the hard problem of consciousness because it seems impenetrable from the outside to know if something's having a conscious experience um and i really like um the idea of also like the hard problem of matter which is related to the hard problem of consciousness which is you don't know the intrinsic properties of an electron not interacting say for example with anything else in the universe all the properties of anything that exists in the universe are divine by its interaction because you have to interact with it in order to be able to observe it so we can only actually know the things that are observable from the outside and so this is one of the reasons that consciousness is hard for science because you're asking questions about something that's subjective and supposed to be intrinsic to what that thing is as it exists and how it feels about existing and so i have thought a lot about this problem and its relationship to the problem of life and the only thing i can come up with to try to make that problem scientifically tractable and also related to how i think about the physics of life is to ask the question are there things that can only happen in the universe because there are physical systems that have subjective experience so does subjective experience have different causes that things that it can cause to occur um that would happen in the absence of that i don't know the answer to that question but i think that's a meaningful ask way of asking the question of consciousness i can't ask if you're having experience right now but i can ask if you having experience right now changes something about you and the way you interact with the world so does stuff happen it's just it's a good question to ask this stuff happen if consciousness is then it's a real physical thing right it has physical consequences i'm a physicist i'm biased so i don't you know i can't get rid of that bias it's really deeply ingrained um i've tried but but i mean you're saying information is physical too so like virtual reality and stimulation all that program is physical too yes everything's physical it's just not physical the way it's represented in our minds right so you i love your twitter so you tweet these like deep thoughts and deep dust that's what a theorist does when she's trying to experiment is tweet it's just like sitting there i mean i can just imagine you sitting there for like hours and all of a sudden just like this thought comes out and you get a little um like inkling into the thought process yeah usually it's like when i'm running between things articulate one of the things you tweeted is ideologically there are many parallels between the search for neural correlates of consciousness and for chemical correlates of life how the neuroscience and astrobiology communities treat those correlates is entirely different can you elaborate against this kind of yeah the parallels it has to do a little bit with the consciousness and the and the matter thing you're talking about yeah it does and i i can't remember what state of mind i was when i was actually thinking about that but um but i think part of it is but you never thought you're gonna have to analyze your own twitter no i didn't it's an interesting uh historical juxtaposition of thinking so the tweet is a historical uh you're doing an assembly experiment right now because you're bringing a thought from the past into the present and trying to actually in the lab yeah yeah this is this is experimental science right here okay on the podcast live um so so go let's see how the consciousness evolves on this one yeah so um in neuroscience it's kind of accepted that we can't get the subjective aspect of consciousness so people are very interested in what would be a correlate of consciousness so um so that's a correlation a correlate is a feature that relates to conscious activity so for example um you know a verbal report is a correlate of consciousness because um you know i can tell you when i'm conscious and then when i'm sleeping for example i can't tell you i'm conscious so we have this assumption that you're not conscious when you're sleeping and you're conscious when you're awake yeah um and so so that's sort of like a a very obvious example but uh neuroscientists which you know i'm no neuroscientist and i'm not an expert in this field so um but you know they have very sophisticated ways of measuring you know activity in our brain and trying to relate that to verbal report and other proxies for whether someone is experiencing something um and that's what is meant by neural correlates um and then so when people are trying to think about um studying consciousness or developing theories for consciousness they often are trying to build an experimental bridge to these neural correlates recognizing the fact that a neural correlate may or may not correspond to consciousness because that problem's hard and there's all these associated issues to it so that that's from a neuroscience perspective it's like fake it till you make it so you pretty much yeah you fake whatever the correlates are and hopefully that the uh that's going to uh summon the thing that is consciousness or something like that and so the same thing on the chemical correlates of life is it that sounds like that's an awesome concept is that something that people no i just made that up okay that was the originals to that tweet you can cite the tweet maybe i'll write it in a paper someday uh chemical correlates of life that's a good title i mean first of all your your papers too that people should check out have great titles or paper papers you're involved with so your tweets and titles are are stellar and also your ideas but the tweets and titles are much more important of course so these will live longer yeah they're much more diffused though um well it's yeah it's the tweet is the trojan horse or the idea that that sticks on for a long time okay so is there anything to say about the chemical coils you're saying there are similar kind of ways of thinking about it but uh you you mentioned about the communities yeah so i think in astrobiology it's not um there's no concept of chemical correlates of life we don't think about it that way we think if we find molecules that are involved in biology we found life so i think i i i think one of my motivations there was just to separate the fact that life has abstract properties associated to it they become imprinted in in material substrates um and those substrates are correlates for that thing but they are not necessarily the thing we're actually looking for the thing that we're looking for is the physics that's organizing that system to begin with not the particular molecules um in the same sense that that you know your consciousness is not your brain it's it's it it's instantiated in your brain that you know it has to have a physical substrate but it's not the the matter is not the thing that you're looking at it's some other at least not in the way that we have come to look at matter you know with traditional physics and things there's there's something else there and it might be this feature of history i was talking about our time being actually you know physically represented there do you think consciousness can be engineered yes in the same way that life can be well that was a fast answer i didn't even think about that that's interesting you don't have a free will that was no i do have free will but it's interesting because some i mean i you know you know you're backtracking no no that was predestined yeah no no no i do believe in free will but i also think that there's kind of kind of an interesting um you know like what you're you speaking about consciousness what are you consciously aware of versus like what is your subconscious brain actually processing and doing and and sometimes there's conflict between your consciousness and your subconsciousness or your consciousness a little slower than your subconscious and intuition is a really important feature of that and so a lot of the ways i do my science is guided by intuition so when i give fast answers like that i think it's usually because i haven't really thought about them and therefore that's probably telling me something let's continue the deep analysis of your tweets [Laughter] you said that determinism in a tweet determinism and randomness play important roles in understanding what life is so let me ask on this topic of free will what is determinism what is randomness and why the heck do they have anything to do with understanding life yeah and you threw free will in there just throwing all the the stuff in the bag are they not related no no they are they are related then no no that's all right i was being unfair you didn't even capitalize the tweet by the way it was all lower case i must have been angry oh that was was saying can you analyze the emotion behind that no i actually did frustration yeah maybe so i already argued that i don't think that can happen without that whole causal history and so i guess in some sense um the determinism for me arises because of the causal history um and i'm not really sure actually about whether the universe is random or deterministic i just had this sort of intuition for a long time i'm not sure if i agree with it anymore but it's still kind of lingering and i don't know what to do with this question but it seems to me you know so there's you ask the question what is life but you could also why life why does life exist what does the universe need life for not that the universe has needs but you know we have to anthropocentrize things sometimes to talk about them um and i had this feeling that if it was possible for a cup or a desk ornament or a phone on mars to spontaneously fluctuate into existence the universe didn't need life to create those objects it wasn't necessary for their existence it was just a random fluke event and so somehow to me it seems that it can't be that those things formed by rand random processes they actually have to have a set of causes that accrue and form those things and they have to have that history and so it seems to me that that life was somehow deeply related to the question of whether the underlying rules of our universe had randomness in them or they were fully deterministic and in some ways you can think about life as being the most deterministic part of physics because it's where the causes are um precise in some sense um or most stable so like most stable yes most reliable most reliable for for our for how we for the tools of physics but what um right well so where's the randomness come from then if okay so you you were at uh speaking with i've gone in a tangent so i'm not sure where we are in the yeah all of the universe is a kind of tangent so uh we're embracing the tangent so free will you believe at this current time that you have free will i believe my whole life i have free will what is illusion i still believe it you still believe it so uh at the same time you think that in your conception of the universe causality seems to be pretty fundamental that's right which kind of wants the universe to be deterministic so how the heck because i mean you think you have a free will and yet you value causality um because i depart from the conception of physics that you can write down an initial condition and a fixed law of motion and that will describe everything there's no incompatibility if you are willing to reject that assertion so where is the randomness where's the magic that gives birth to the free will is it the randomness of the laws of physics no free um in my mind what free will is is the fact that i i as a physical system have causal control over certain things i don't have causal control over everything but i have a certain set of things and i'm also um you know as i described sort of a nexus of a particular set of histories that exist in the universe on a particular set of futures that might exist and those futures that might exist are in part specified by my physical configuration as me um and therefore you know it may not be free will in the traditional sense i don't even know what people mean when they're talking about free will honestly it's like the whole discussion is really muddled but in the sense that i am a causal agent if you want to call it that that exists in the universe and there are certain things that happen because i exist as me then yes i have free will no but do you sarah have a choice about what's going to happen next oh i see um if the universe could i have if i run this yes i think so you have a choice where's the choice come from is it i think that's related to the physics of consciousness so one of the things i didn't say about that i don't know maybe this is me just being hopeful um because i maybe i just want to have free will but i don't think that we can rule out the possibility because i don't think that we understand enough about any of these problems but i think one of the things that's interesting for me about the sort of inversion of the question of consciousness that i proposed is one of the features that that we do is we have imagination right and people don't think about imagination as a physical thing but it is a physical thing it exists in the universe right um and so i'm like really intrigued by the fact that say humans for you know another physical system could do this too it's not special to humans but uh you know for centuries imagined flying machines and rockets and then we finally built them right so they were they were represented in our minds and on the pages of things that we drew for hundreds of years before we could build those physical objects in the universe but certainly the existence of rockets is in part causally you know caused by the fact that we could imagine them um and so um so there seems to be this property that some things don't exist they've never physically existed in the universe but we can imagine the possibility of them existing and then cause them to exist maybe individually or collectively um and i think that property is related to what i would say about having choice or free will because that set of possibilities that thing those set of things that you can imagine is not constrained to your local physical environment and history and this is what's a little bit different about intelligence as we see it in humans and ai that we want to build than biological intelligence because biological intelligence is predicated completely on the history of things it's seen in the past but something happened with the neural architectures that evolved in multicellular organisms that they don't just have access to the past history of their particular you know set of events but they can imagine things that haven't happened aren't on their timeline and as long as they're consistent with the laws of physics make them happen so this is fascinating physics but it exists so there you go i mean in some sense if you look at like general relativity and gravity morphing space time in that same way maybe whatever the physics of consciousness might be it might be morphing that's like what free will is it's morphing like the space just like ideas make rockets come to life it's somehow changing the space of possible realizations of like whatever's yeah okay but life is kind of basically if you want to think about it like life is sort of changing the probability distributions over what can exist that's the physics of what life is and then consciousness is a sort of layered property your imagination on top of it that kind of scrambles that a little bit more and like has you know access to i don't i don't know it's it's kind of it we don't know how to describe it right like that's why it's interesting but it's probabilistic so you do think like god plays dice so let me um no i think the description's probabilistic i don't necessarily think the um underlying physics is probabilistic i think i think i think the way that we can describe this physics is going to be probabilistic and statistical but the under like when we take measurements in the lab but the underlying physics itself might still be deterministic i don't i don't know maybe i'm i it's hard to know what concepts to hold on to so i find myself constantly rejecting concepts but then i have to grab another one and try to hold on to something from intellectual history right well it's possible that our mind is not able to hold the correct concepts of mind at all like right we're not able to even conceive of them correctly maybe the words deterministic or random are not the right even words concepts to be to be holding but maybe you can talk to the theory of everything uh the this attempt in the current set of physical laws to try to unify them is there any hope that once a theory of everything is developed and by theory of everything i mean in a narrow sense of unifying quantum field area and general relativity do you think that will contain some like in order to do that unification you would have to get something that would then give hints about the physics of life physics of existence physics of consciousness yeah i used to not but i actually uh i have become increasingly convinced that it probably will um and part of the reason is um i think i've talked a little bit already about these holes in physics like these the the theories we have in physics you know they have problems they have lots of problems um and they're very deep problems um and we don't know how to patch them um and some of those problems become very evident when you try to patch um quantum mechanics and general relativity together so there is this kind of interesting feature that some of the ways of patching that might actually um closely resemble uh the physics of life and so the place where that actually comes up most and actually we just had a workshop in the beyond center where i work at arizona state university um and lee smolin made this point that he thinks that the theory of quantum gravity when we solve it is going to be the same theory that gives rise to life um and i think that i agree with him on some levels because there's something very interesting where if you look at these sort of causal set theories of gravity where they're looking for space um as being emergent and so space time is an emergent concept from a causal set which is is also sort of related i think to what wolfram's doing with his physics project um it's the same kind of underlying math that we have in in this theory that we've been developing related to life called assembly theory um which is you know basically trying to look at complex objects like molecules and bacteria and living things as sort of uh as basically being assembled from a set of component parts and that they actually encode all the possible histories that they could have in that physical object so the mathematically all these ideas i think are related i think a lot of people are thinking about this from different perspectives and then constructor theory um that david deutsch and kiara marletto have been developing is a totally different angle on it but i think getting at some similar ideas so it's a really interesting time right now i think for the frontiers of physics and how it's relating um to maybe deeper principles about what life is so short answer yes long-winded answer rewind can we talk about aliens anytime so one i think one interesting way to sneak up on the question of what is life is to ask what should we look for in alien life you know if we were to look out into our galaxy and enter the universe and come up with a framework of how to detect alien life what should we be looking for is there like set of rules uh like it's both the tools and the tools that are service census for certain kind of properties of life so what should we look for in alien life yeah so we have a paper actually coming out monday which is collaboration um it's actually really lee cronin's lab but my group worked with him on it and we're working on the theory which is this idea that we should look for life um as high assembly objects what we mean by that is which is actually observationally measurable and this is one of the reasons that i started working with leon these ideas is because being a theorist it's easy to work in a vacuum it's very hard to connect abstract ideas about the nature of life to anything that's experimentally tractable but what his lab has been able to do is develop this method where they look at a molecule and they break it apart into all its component parts and so you say you have some elementary building blocks and you can build up all the ways of putting those together to make the original object and then you look for the shortest path in that space and you say that's sort of the assembly number associated to that object and if that number's higher it assumes that a longer causal history is necessary to produce that object or more information is necessary to specify the creation of that object in the universe now that kind of idea at a superficial level has existed for a long time that kind of idea as a physical observable of molecules is completely novel and what his lab has been able to show is that if you look at a bunch of samples of non-biological things and biological things there's this kind of threshold of assembly where as far as the experimental evidence is and also your intuitive intuition would suggest that by non-biological systems don't produce things with high assembly number so this goes back to the idea like a protein is not going to spontaneously fluctuate into existence on the surface of mars it requires an evolutionary process and a biological architecture to produce a protein you generalize that argument you know a complex molecule or a cup or a desk ornament in this sort of abstract idea of assembly spaces as being the causal history of objects and you can talk about the shortest path from elementary objects to an object given an elementary set of operations and you can experimentally measure that with mass spec and that's basically sort of the idea that's really fascinating i can't get out of my head and start imagining legos and all the legos i've ever built and how many steps what is the shortest path to the final right right to find a little lego castles so they so yeah so then like asking about going to look for alien life the idea is you know most the instruments that nasa builds for example or any of the space agencies looking for life in the universe are looking for chemical correlates of life right but here we have something that is based on properties of molecules it's not a chemical correlate it's agnostic it doesn't care about the molecule it cares about what is the history necessary to produce this molecule how complex is it in terms of how much time is needing how much information is required to produce it so when you observe a thing on another planet you're essentially the process looks like reverse engineering trying to figure out what is the shortest path to create that thing yeah so most yeah and i would say most like most examples of biology or technology don't take the shortest path right but the shortest path is a bound on how hard it is for the universe to make that yeah and so i guess what you and lee are saying that there's a heuristic that's a good metric for uh like better perhaps than chemical correlates yes because it doesn't it's not contingent on looking for the chemistry of life on earth on other planets and it also has a deeper explanatory framework associated to it as far as the kind of theory that we're trying to develop associated to what life is and i think this is one of the problems i have in my my field personally in astrobiology is people observe something on earth say oxygen in the atmosphere or an amino acid in a cell and then they say let's go look for that on another planet let's look for oxygen on exoplanets or let's look for amino acids on mars and then they assume that's a way of looking for life um and it or even phosphine on venus but you know like there's all these examples of let's look for one molecule a molecule is not life life is a system that patterns particular structures into matter that's like it's that's what it is and it doesn't care what molecules are there it's something about the patterns and and that structure and that history um and if you're looking for a molecule you're not testing any hypotheses about the nature of what life is it doesn't tell me anything if we discover oxygen and exoplanet about what kind of life is there just oxygen on an exoplanet it's not there there's i i guess i think like when you think about the question are we alone in the universe that's a pretty freaking deep question it should have a freaking deep answer it shouldn't just be there's a molecule and an exoplanet wow we solved the problem it should tell us something meaningful about our existence and i feel like we've fallen short on how we're searching for life in terms of actually searching for things like us in this kind of deeper way but how do you do that initial kind of say i'm walking down the street and i'm looking for that double take test of like like what the hell is that like that that initial like how do we look for the possibility of weirdness at the possibility of high assembly number well yeah if they don't have two eyes and are green you know i would have probably already solved the problem right there's another nobel prize in there somewhere i think actually um well i think it's it's kind of so so there is a bias here right so we've evolved to recognize life on earth right like i you know children at a very early age can tell the difference between a puppy and a plant and then the plant and a chair for example you know like it just it seems innate um and so i think and also because we're life um you know i think like there's this implicit bias that we should know it when we see it and it should be completely obvious to us um but there are a lot of features of our universe that are not completely obvious to us like the fact that this table is made of atoms and that i'm sitting in a gravitational potential well right now um and i guess um my point with this is i think life is much less obvious than we think it is and so it could be in many more forms than we think it is um and i guess let's go back to the point about being open-minded that we may not know what alien life looks like it might not even be possible to interact with alien life because maybe something about you know our our informational lineage it makes it impossible for information from an alien to be copied to us therefore there's no you know so to speak communication channel and i don't mean you know verbal communication just it's not in our observational space like you know like you know there's there's fundamental questions about why we observe the universe in position rather than momentum but we also you know observe it in terms of certain informational patterns and things like that's what our brain constructs and maybe aliens just interact with a different part of reality than we do that's wildly speculative but i think i think um it's possible it's possible and i think it's consistent with the physics so i think the best ways we can ask questions are about life and chemistry and asking questions about if information is a real physical thing what would its signatures be in matter um and and how do we recognize those and i think the ones that are most obvious are the ones i've already articulated you have these objects that seem completely improbable for the universe to produce because the universe doesn't have the design of that object in the laws so therefore an object had to evolve we we talked we call it evolution but it had to be produced by the universe that then had all of the possible tasks to make that object um specified i mean there's some like there's an engineering question here of are there sensors we can create that can give us uh can help us discover certain pockets of high assemblies yeah aliens like i mean there is a hope setting dogs and chairs aside there's a hope that visually and we could detect like because our universe i mean at least the way we look at it now like this three-dimensional like space-time we can visually comprehend it it's interesting to think like if we got to hang out you know if there's an alien in this room like would we be able to detect it with our current sensors not the fancy kinds but but like what you're standing over there yeah standing over there or maybe like in this carpet see there's all these kinds of patterns right yeah uh i don't know if if i don't know if this carpet is an alien well so i see what you're saying um so assembly theory is pretty general like i mean we've been applying it to molecules because it makes sense applied to molecules but it's supposed to explain life um you know like the physics of life so it should explain you know the things in this room in addition to molecules um so i guess uh and you can apply it to images and things so i guess the idea you know you could explore is just looking at everything on planet earth in terms of its assembly structure and then looking for things that aren't part of our biological lineage if they have high assembly they might be aliens on earth i mean that that is a very kind of rigorous computer vision question can we visually is there a strong correlation between certain kind of high assembly objects when they get to the scale where they're visually observable and some like when it's say uh projected onto a 2d plane can we right can we figure out something right i am glad you brought up a computer vision point because for a while i had this kind of thought in my mind that we can't even see ourselves clearly so one of the things you know people are worried about artificial intelligence for a lot of reasons but i think it's really fascinating because it's like the first time in history that we're building a system that can help us understand ourselves so like you know people talk about ai physics but like um you know when i when i look at another person i don't see them as a four billion year lineage but that's what they are and so is everything here right so imagine that we built artificial systems that could actually see that feature of us what else would they see and i think that's what you're asking and i think i think that would be so cool i want that to happen but i think i think we're a little ways off from it but yeah we're going there i hope okay let me ask you uh i apologize ahead of time but let me ask you the internet question so you're a physicist you ask rigorous questions about the physics of existence and these models of high assembly objects now when the internet would see an alien they would ask two questions one can i eat it and two can have sex with it yes so so you kind of mentioned that it's very difficult it's possible that we may not be even able to communicate with it right but i think the internet has more hope than we do yes it's a hopeful place yes uh do you do you think in terms of like interacting on this very primal level of of sharing resources like what would aliens eat what would we eat would we eat the same thing would could we potentially eat each other uh one one person eats the other or or the aliens eat us and the same thing with not sex in general reproduction but genetically mixing stuff like would we would be able to mix genetic information maybe not genetic but maybe information right and i think part of your question is like so so if you if you think of life as like this history of events that happen in the universe like there's this question of like how divergent are those histories right so when we get to the scale of technology it's possible to imagine imagine although we can't even do it like imagine all the possible technologies that could exist in the universe but if you think about all the possible chemistries somehow that seems like a lower dimensional space and a lower set of possibilities so it might be that like when we interact with aliens we do have to go back to those more basal levels to figure out sort of what the map is right um like the sort of where we have a common history we all we must have a common history somewhere in the universe but in order to be able to actually interact in a meaningful way you have to have some shared history i mean the reason we can exchange genetic information in each other's food or eat each other as food is because we have a shared history so we have to find that shared history the other we have to find the common ancestor in this causality map the the something yes yes and we have a last universal common ancestor for all life on earth which i think is sort of the nexus of that causality map for life on earth but the question is where would other aliens diverge on that sound and i mean that so say there's a lot of aliens out there in the universe each each set of organisms will probably have like a number you know like erdos number of like how far like how far our common ancestor is and so the closer the common ancestor like it is on earth the more like each other the more likely we are to be able to have sexual reproduction well it's like sort of like humans having common culture and languages right yeah exactly language communication it might take a lot of work though with an alien because you really have to get over a language barrier oh boy so it says communication it's uh uh resources i mean it's all the whole and i think tied into that is the questions of like who's gonna harm who right and actually definitions parents approve you know all those kind of questions whether the common ancestor approves yeah that's just very true uh how many alien civilizations do you think are out there i don't have intuition for that um which i i have always thought was deeply intriguing so and and part of this uh i mean i say it specifically is i don't have intuition for that because it's like one of those questions that you feel around for a while and you really just you you can't see it um even though it might be right there and um in that sense it's a little like the quantum to classical transition you're like really talking about two different kinds of physics and i think that's kind of part of the problem once we understand the physics that question might become more meaningful um but there's also this other issue um uh and this was really instilled in me by my mentor paul davies when i was a postdoc because he always talks about how you know whether aliens are common or rare is kind of just um you know it's like you know it follows a wave of popularity and it just depends on like the mood of you know what the culture is at the time and i always thought that was kind of an intriguing observation but but also there's this you know set of points about if you go by observational evidence which we're supposed to do with scientists right um you know we have evidence of us and one original life event from which we emerged and people want to make arguments that because that event was rapid or because there's other planets that have properties similar to ours that that event should be common but you actually can't reason on that because our existence observing that event is contingent on that event happening which means it could have been completely improbable or very common and brandon carter like clearly articulated that in terms of anthropic arguments um a few decades ago so so there is this kind of issue that we have to contend with dealing with life that's closer to home than we have to deal with with any other problems in physics which we're talking about the physics of ourselves and when you're asked about the original life event that event happening in the universe at least is like our existence is contingent on it um and so you can think about sort of fine tuning arguments um that way too so um but the the sort of odder part of it is like when i think about uh how likely it is i think it's because we don't understand this mechanism yet about how information can be generated spontaneously that i like because i can't see that physics clearly yet even though i have a lot of you know like some things around the space of it in my mind i can't articulate how likely that process is um so my honest answer is i don't know and it sometimes feels like a cop-out but i feel like that's a more honest answer and a more meaningful way of making progress than um what a lot of people want to do which is say oh well we have a one-in-ten chance of having on an exoplanet with earth-like properties because there's lots of earth-like planets out there and life happen fast on earth well so i have kind of a follow-up question but as a side comment what i really am enjoying about the way you're talking about human beings is you always say not to make yourself conscious about it because i really really enjoy it do you say we yes you don't say humans you say because often times like and you know i don't know evolutionary biologists will kind of put yourself out yes as an observer but you're it's it's kind of fascinating to think that you as a human are struggling about your own origins yes that's the problem and yeah and i i think um i don't do that deliberately but i do think that way and this is sort of the inversion from the logic of physics because physics as it's always been constructed has treated us as external observers of the universe and we are not part of the universe and this is why the problem of life i think demands completely new thinking because we have to think about ourselves as minds that exist in the universe and are at this particular moment in history and looking out at the things around us and trying to understand what we are inside the system not outside the system we don't have descriptions at a fundamental level that describe us as inside the system and this was my problem with cellular automata also you're always an external observer for a cellular automata you're not in the system what does the cellular automata look like from the inside i think you just broke my brain with that question exactly but i thought about that for a long time i'm gonna uh yeah that's a that's a really clean formulation of a very fundamental question because you can only to understand cellular autonomy you have to be inside of it but as a human sort of a poetic romantic question does it make you sad does it make you hopeful whether we're alone or not like in the different possible versions of that if we're the highest assembly object in the entire universe does that at this moment in time at this moment in the causality because we might i assume we have a future well we definitely have a future and the question is well yeah where that future decreases the assembly like it could be where at the peak or we could be just um that would be inconsistent with the physics in my mind but so so i i should give a caveat i've given the the caveat that i'm biased as a physicist but i'm also biased as an eternal optimist so pretty much all of my modes of operation for building theories about the world are not like an occam's razor what's the simplest explanation but what's the most optimistic explanation and part of the reason for that is if you really think explanations have causal power um in the sense that our theo like the fact that we have theories about the world has enabled technologies and physically transformed the world around us i think i have to take seriously that as a part of the physics i want to describe and try to build theories of reality that are optimistic about what's coming next because the theories are in part the causes of what comes next so there could be a physics of hope or physics of optimism in there too yes because um that seems like also i mean optimism does seem to be a kind of engine that results in innovation yes so this is dr like what why the hell are we trying to come up with new stuff oh so um so i made this point about thinking life is the physics of existence and it's not just the physics of existence it's the physics of more things existing so i think one of these drives the yeah creativity like optimism the story so if you like people like entropy i don't i don't like entropy as it was formulated in the 1800s i think it's an antiquated concept but um but this idea of maximizing over the possible number of states that could exist imagine the universe is actually trying to maximize over the number of things that could physically exist what would be the best way to do that the best way to do that would be evolve intelligent technological things that could explore that space so okay that's talking about alien life out there in the universe but you've also earlier in the conversation mentioned the shadow biosphere so is it possible that we have weird life here on earth that we're just not like even in a high assembly formulation of life yeah that we're just not paying attention to we're blind to like life we're potentially able to detect but we're blind to and maybe you could say what is the shadow bias sure sure yeah the shadow biosphere is this idea that there might have been other original life events that happened on earth that were independent from the original life event that led to us and all of the life that we know on earth and therefore there could be aliens in the sense they have a different origin event living among us um uh and it was proposed by a number of people um but one of them was a paul davies that i mentioned earlier as my mentor and he has a really a cute way of saying that aliens could be right under our noses or even in our noses uh with a british accent it sounds better but um but uh but anyway so the idea is like it could literally be anywhere around us um and if you think actually about the discovery of like viruses and bacteria you know for a long time we didn't they were kind of a shadow biosphere it was life that was around us but invisible um and but this takes it a little bit further in saying that you know all of those examples viruses bacteria and everything that we've discovered so far has this common ancestry in the last universal common ancestor of life on earth so maybe there was a different origin event and that life is weirder still and might be among us and we could find it we don't have to go out and stars live for aliens just here on earth do you think that's a serious possibility that we should explore with the tools of science like this should be a serious effort i think um yes and no um and i mean yes because i think it's a serious hypothesis um and i think it's worth exploring and it is certainly more economical to look for signs of alien life on earth than it is to go and build spacecraft and send robots to other planets and that was one of the reasons it was proposed is well if we do find an example of another original life on earth it's hugely informative because it means the original life is not a rare event if it happened twice on the same planet that means it's probably pretty probable given conditions are right um so it has huge potential scientific impact not to mention the fact that you might have like biochemistry and stuff that's informative for like medicine and stuff like that but um but i think that the thing for me that's challenging about it and this really comes from my own work like thinking about life as a planetary scale process and also trying to understand sometimes what i call like the statistical mechanics of biochemistry but large scale statistical patterns in the chemistry that life uses on earth there are a lot of regularities there and life does seem to have planetary scale organization that's consistent even with some of the patterns that we see at the individual scale so if you think life is a planetary scale phenomena and the chemistry of life has to be sort of um not just it's not an individual is not necessarily the fundamental unit of life right the fundamental you know life is these uh informational lineages and they're kind of you know they intersect over spatial scales so everything on earth is kind of related by the common causal history yeah so it's hard for me based on the way i think about the physics and also some of the stuff that my group has done to really think that there could be uh evidence or there could be a second sample of life on earth but i think there are ways that we need to be more concrete about that and i have thought a little bit about like um you know like you can represent the chemistry in an individual cell as a network and then those networks something my group has shown actually scale with the same properties so ecosystems have the same properties as individuals as planetary scale and then you could imagine if you had alien chemistry intermixed in there that scaling would be broken so if there's some robustness property or something associated to it and you get alien chemistry in there it just breaks everything and you don't have a planetary ecosystem functioning an individual's functioning across all these scales so i guess what i'm arguing is life is not a scale-dependent phenomena it's not just cellular life so if you have a shadow biosphere it has to be integrated with all of these other scales in it and that and that would lose the meaning of the word shadow biosphere i think so yeah so so i i it's an open question right and i think it would it would tell us a lot so there has been very minimal effort of people to look for a shadow biosphere but then the question it could be possible that uh there's like sufficiently distinct planets within one planet meaning like environments within one planet yeah like i don't know i've been looking uh recently uh because of having a chat with catherine declare about io the moon of jupiter that's like all volcanoes and volcanoes a badass but like yeah imagining [Laughter] imagining life inside volcanoes right like yeah it seems like sufficiently chemically different like to be living in the darkness right where there's a lot of heat and maybe you could have different earths on like a planet yeah or like if you go deep enough in the crust maybe there's like a layer where there's no life and then there's suddenly life again and maybe those you know lizard men or whatever that people dream about are really down there um i know that's a little flippant but but really like there could be like chemical cycles deep in those crests that might be alive and are completely distinct in chemical or origin to surface life right that they wouldn't be interacting with each other yeah and that's one of the proposals for the shadow biosphere is like sometimes people talk about it as being geologically or geographically distinct that it might be you know you have no life for this region and then a different example and then sometimes people talk about it being chemically distinct that the chemistry is sufficiently different that it's completely orthogonal or non-interacting with our chemistry it seems to me at least the chemistry is a a more powerful boundary yes than than than geographic it just seems like life finds a way literally to travel yeah yes what do you think about all these ufo sightings so to me it's really inspiring it's yet another localized way to dream about right the mysterious that is out there yeah so i've actually been more intrigued by the cultural phenomena ufos than the phenomena ufos themselves because i think it's intriguing about how uh we are preparing ourselves mentally for understanding others and how we have thought about that historically and what the sort of modern incarnations of that are um it's more like i want an explanation for us that's my motivation and having some you know streaks across the sky or something and saying that's aliens it doesn't tell you anything um so unless you have a deeper explanation and you have you know more lines of uh you know where is this going to take us in the future it's just not as interesting to me as the problem of understanding life itself and aliens as a more general phenomenon i do think it's uh just as you said a good way to psychologically and sociologically prepare ourselves to sort of like what would that look like right and very importantly which is what a lot of people talk about politically sort of uh there's this idea from the so it came from the soviet union of like the cold war and we have to hide secrets yeah there's some way in us searching for life on other planets are searching for life in general the the way we've done government in the past yeah we tend to think of all new things as potential military secrets so we want to hide them and one of the ways that people kind of look at ufo sightings is like like maybe we shouldn't hide this stuff like what is the government hiding right i think that's a really you know in one sense it's a conspiratorial question but i think in another it's an inspiration to change the way we do government to where secrets don't uh maybe there are times when you want to keep secrets as military secrets but maybe we need to release a lot more stuff and see us as a human species as together in this whole search yeah the public engagement part there is really interesting and it's almost like a challenge to the way we've done stuff in the past in terms of keeping secrets when they're not so like the the first step if you don't know how something how something works if there's a mysterious thing the the first instinct should not be like let's hide it put it in the closet right so that the chinese or the russian government or whatever government doesn't uh doesn't find it maybe the first one the first instinct should be let's understand it yeah perhaps let's understand it together right no i think that's good and and something i realized recently that i never thought was going to be a problem but i think this actually helps with quite a bit is because so many um people nowadays believe we've already made contact that as an astrobiologist if we you know actually want to understand life and make contact we kind of have to deconstruct the narratives we've already built from ourselves and kind of unteach ourselves that we've learned about aliens and then reteach ourselves so there's this really interesting sort of dialogue there um and making it open to the public that they actually have to think critically about it and they see the evidence for themselves i think is really important for that process yeah the restriction that aliens might be way weirder than we can imagine yes yes i'm i'm pretty sure they're probably weirder than we can imagine okay we've uh in 2020 and still living through a pandemic setting the the the the political and all those kinds of things aside i've always found viruses fascinating as as living as dynamical systems i was going to say living systems but i've always kind of thought of them as living you know but that's a whole nother kind of discussion maybe it'd be great to put that on the table one do you find viruses beautiful slash terrifying and two do you think they're living things or there's some aspect to them for our discussion of life that makes them living i mean living in a pandemic saying viruses are beautiful is probably a hard thing but i do find them beautiful to a degree i think even even even in the sense of mediating a global pandemic there's something like deeply intriguing there because you know these these are tiny tiny little things right and yet they can um uh you know essentially um like cause a seizure like you know handicap an entire civilization at a global scale so just that intersection of between you know our perceived invincibility and our susceptibility to things and also the interaction across scales of those things is just a really amazing feature of our world most technology whether it's viruses or ai that can scale scale in an exponential way like right kind of run you know like as opposed to like one thing makes another thing makes another thing it's one thing makes two things and those two things make four things and then like that kind of process also seems to be fundamental to life yes and uh it's terrifying because in in a matter of in a very short time scale it can uh if it's good at being life whatever that is yeah it can quickly overtake the the other competing forms of life right and that's scary both for ai and for viruses and it seems like understanding these processes that are underlying viruses and i don't mean like on the virology or biology side but on some kind of more computational physics yeah perspective as we've been talking about yeah seems to be really important to figure out how humans can survive right along with these kinds of this kind of life and perhaps becoming a multi-planetary species is is a part of that like there's no maybe like what we'll figure out from a physics perspective is like there's no way any living system can be stable for a prolonged period of time and survive unless it expands exponentially throughout like we have to multiply otherwise anything that doesn't multiply exponentially will die eventually maybe that's a fundamental law um maybe i don't know i you know i always get really bothered by these darwinian narratives that are like you know like the fittest replicator wins and things and i don't i just don't feel like that's exact exactly what's going on i think like the copying of information is sort of ancillary to this other process of creativity right so like the drive is actually the drive is creativity but if you want to keep the creativity that's existed in the past it has to be copied into the future right so replication like if you so that for me is so i had this set of arguments um with michael lachman and lee cronin about the like life being about persistence they thought it was about persistence and like survival of fittest kind of thing and i'm like no it's about existence it's like because when you're talking about that it's easy to say that in retrospect you can post select on the things that survived and then say why they survived but um but you can't do that going forward that's really profound that survival is just a nice little side effect feature of maximizing creativity but it doesn't need to be there yeah i like people yeah yeah like i said i like optimistic theories well i don't know if that's up to me that that could be terrifying to people because yeah because uh you know a system that maximizes creativity may very quickly get rid of humans for some reason if it comes up with some other creative i mean yeah forms of existence yeah right this is the ai thing it's like the moment you have an ai system that can that can flourish in the space of ideas or in some other space much more effectively than humans and it's sufficiently integrated into into the physical space to be able to modify the environment i think we'll just be like the core genetic architecture or something we'll be like the dna for ai right it's like we haven't lost the past informational architectures on this planet they're still there yeah also they'll ai will use our brains in some part to like like ride like it'll accelerate the exchange of ideas that's the neural link dream is that well the humans will be still around because you're saying architecture yeah but i don't i don't even think they necessarily need to tap in our brains i mean just collectively we do interesting things what if they were just using like the patterns in our communication or something oh without controlling it just observing well i i don't know in what sense do you control the chemistry happening in your body hmm yeah i i mean i i obviously i don't know i'm just i i just like the way i look at like people look at ai and then they look at this thing that's bigger than us and is coming in the future and is smarter than us and i think though that looking at the past history of life on the planet and what information has been doing for the last four billion years is probably very informative to asking questions about what's coming next um and i don't one is planetary scale transitions are really important for new phases so the global internet and sort of global integration of our technology i think it's an important thing so that's again life is a planetary scale phenomena but we're an integrated component of that phenomenon i don't really see that the technology is going to replace us in that way it's just going to keep scaffolding and building and and i also don't have an idea that we're going to build ai in a box i think ai is going to emerge agi to be is a planetary scale phenomena that's going to emerge from our technology planetary scale phenomena but do you think an agi is not distinct from humans we're the whole package the whole package comes as a planetary scale phenomenon and that goes back to the fact that like you were you know asking questions about you as an individual like what are you as an individual you're like a packet of information that exists in the particular physical thing that is you we're all just packets of information and some of us are aggregates in certain ways but it's all just kind of exchanging and propagating right and processing is your packet of information that you've continually referred to as sarah afraid of the dissipation of the death of that packet are you afraid of death do you ponder death does death have meaning in this process of creativity i think i have the natural biological urge that everyone has to fear death um i think the thing that i think is interesting is if i think about it rationally i'm not necessarily afraid of death for me because i won't be aware of being dead um but i am afraid like for my kids because it matters to them if i die um so so again like i think death becomes more significant as a collective property not as an individual one yeah but isn't there something to fear about the fact that the way like the creative uh the complexity of information that's been like created in you yeah the the fact that it kind of breaks apart and disappears it doesn't but i don't think it disappears it's just not me anymore right so you're but the that process of you it being not you anymore that doesn't scare you of course it does the mystery of it i mean the yeah but i guess i'm heartened by the fact that there will be some imprints of the fact that i existed still in the universe after i leave it yeah but there'll be a okay and also that has to do with my perception of time right so you know i perceive time as flowing but that might not be the case i mean this is you know standard physicists comfort is you know every time moment exists you know and is you know there's no and the flow of time is just our perception of you know us um you know us changing um so you can travel back in time and that's comforting like from a physics condition no no i'm not talking about traveling back in time i'm just saying that the moments in the past still exist um now whether the moments in the future exist or not is a different question that's not comforting to me in terms of death the flow of time is not that does not i think uh i think it's i think there's no comfort in the face of death for what we are uh because we like existing and i think it's especially true if you if you love life and you love what life is do you think there's a certain sense in which the fear of death or the fear of non-existence maybe fear is not the right word is the actual very phenomena that gives birth to existence like maybe death is fundamental like this it just feels like freaking out oh this ride ends is actually like the that's that's the thing that gives birth to this this whole thing yeah that like it's constantly is matter constantly freaking out about the fact that it's good enough no i think i think things like to exist i think they want to exist yeah there's a there's a desire whatever to exist yeah and there's a drive to exist and there's a drive for more things to exist i guess um yeah i would like to i like existing i like i like i like it a lot um and i don't know it any other way but see i don't even know if i like existing i think i really don't like not existing yes yeah that's you uh yeah yeah maybe it's that i some days i you know i might like existing less than others but yes but like i think those are like surface feelings there is yeah it seems like there's something fundamental about wanting to exist no i think that's right but i but i think to your point that that might go back to the more fundamental idea that you know if life is the physics of existence and maximizing existence individual organisms of course want to maximize their existence and everything you know like wants to exist but i guess for me the small comfort is my existence matters to future existence speaking of future existence is there advice you can give to future pockets of existences aka young people about life you've had uh you've worn many hats you've taken on some of the biggest problems in the universe is there advice you can give to young people about life about career about existing uh maybe not about the last one um you know a lot of people ask me this question about like like working on such hard problems like how can you make a successful career out of that but i think for me it couldn't be otherwise like i have to to be fulfilled you have to work on things you care about and that's always kind of driven me and that's been disciplined department um uh and sort of superficial level problem independent because i'm i i started at community college actually and i was taking a physics class and i learned about uh you know magnetic monopoles and they we didn't know if they existed in the universe and but we could predict them and we could go look for them and i was so deeply intrigued by this idea that we had this mathematical formula to go look for things and then i wanted to become a theoretical physicist because of that but that actually wasn't my driving question i realized my driving question is the nature of the correspondence between our minds and physical reality and what we are and that question's very deep so you can work across a lot of fields doing that but i think without that driving question i never would have been able to do all the things that i've done it's really the passion that drives it and i and usually when when students ask me these kind of questions i i tell them like you have to find something you really care about working on because if you don't really care about it a you're not going to be your best at it and b it's not going to be worth your time why would you spend your time working on something you're not interested in so find the driving questions yeah find the driving question find your your passion i mean i think passion makes a huge difference in terms of creativity talent and potential and also being able to tolerate all the hard things that come with any career or life yeah i've had a bunch of moments in my life where i've just been captivated by some beautiful phenomena and i guess being rigorous about it and asking what is the question underlying this phenomenon phenomena like robots bring a smile to my face and yeah that's cool forming a question of like why the hell is this so fascinating yeah why is this uh specifically the human robot interaction question that's something beautiful is brought to life when humans and robots interact understanding that deeply yeah it's like okay so this is going to be my life work then i don't know what the hell it is but that that's what i want to do interesting and doing that doing that for whatever the hell gives you that kind of feeling i guess is the point yeah am i allowed to ask you a question sure okay um on that point because i like um at this colleague that suggests the idea that like consciousness might be contagious and so interacting with things you know isn't it no yeah it's an interesting idea right so i'm i'm wondering like sort of you know the motivation there is it the motivation that you want more of the universe to appreciate things the way we do and appreciate those interactions or is it really more the enjoyment of the human in those interactions like is it is it i don't do you know what i'm asking yeah yeah see i think consciousness is created in the interaction between yes things yes so the joy is in the creation of consciousness and i see i really like the idea that it doesn't just have to be two humans creating costumes together it could be humans and other entities yeah we talked offline about dogs and other pets and so on there's a magic i mean i've been calling it love is this beauty of the human experience that's created and it just feels like fascinating that you could do that with a robotic system right and right there's something really powerful at least to me about engineering systems that allow you to create some of the magic of the human experience because then you get to understand what it takes at least get inklings of what it takes to uh to to create consciousness and i i don't get this um you know philosophers get really upset about this idea that sort of the illusion of consciousness is consciousness but i really like the idea of engineering systems that fool you into thinking they're conscious right because that's sufficient to create the magical experience right because it's the interaction yeah it's the interaction yeah right and this is the russian head i wear which is like i think i think there's an ocean of loneliness in the world i think we're deeply lonely we're not even allowing ourselves to acknowledge that and i kind of think that's what love is between romantic love and friendship is two people kind of getting a little bit like like uh alleviating for a brief moment that loneliness that loneliness but not but we're not they're it's not the full aspect of that loneliness like we're desperately alone we're desperately afraid of not existing right i have that kind of sense and i just want to explore that ocean of loneliness more right like create a submarine that goes into the depth of that loneliness so creating systems that can truly hear you right truly listen make the universe a less lonely place exactly uh let me ask you about uh the meaning you've brought up why yeah the physics of why what do you think is the meaning of our particular planets set of existences and uh the universe in general um the meaning of life yes someone once told me as a physicist i'm not allowed to ask why questions but i don't believe that so um i think i think what we are is the creative process in the universe i think and i for me that's the meaning um the ability to yeah to create more possibilities and more things to exist how what what is uh dostoevsky has the saying beauty will save the the world what is uh is there a connection between creation and beauty i think so so is that like are they is his beauty a correlate of creation it might be i don't know um i mean why is it i you know a lot of people have asked these kind of questions but like why is it we have such an emotional response to intellectual activity or creativity um and that seems kind of a deep question to me like it seems very intrinsic to what we are so i i do have an interest in the questions i ask because i think they're beautiful and i think the universe is beautiful and um i'm just so deeply fascinated by the fact that i exist at all um and so maybe maybe it's that you know that that intrinsic feeling of beauty that's in part driving you know the physics of creating more things so they could be deeply related in that way well i don't think there's a better way to end it i think this conversation was beautiful thank you so much for uh wasting all your valuable time with me today i really really appreciated sarah this is an honor i hope we get a chance to talk again i hope uh like i mentioned to you offline we get a chance to talk with lee you guys have a beautiful um like intellectual chemistry that's fascinating to listen to so i'm a huge fan of both of you and i can't wait to see what you do next thanks so much great to be here thanks for listening to this conversation with sarah walker and thank you to athletic greens nut sweet blinkist and magic spoon check them out in the description to support this podcast and now let me leave you with some words from robert frost one of my favorite poets in three words i can sum up everything i've learned about life it goes on thank you for listening i hope to see you next time

Channel: Lex Fridman

Views: 295,681

Rating: 4.8832893 out of 5

Keywords: agi, ai, ai podcast, artificial intelligence, artificial intelligence podcast, lex ai, lex fridman, lex jre, lex mit, lex podcast, mit ai, sara walker

Id: -tDQ74I3Ovs

Length: 119min 28sec (7168 seconds)

Published: Fri Jul 09 2021

Reddit Comments

[u/noetic11]

I love this woman. Pure genius.

[u/valschermjager]

During the intro, Lex mentioned that he’s been getting feedback to slow down the release of new shows.

Luckily he said he actually plans on upping the tempo of new interviews, but I don’t understand that kind of feedback. I mean, you can always just listen to fewer of them, right?

[u/UncleWeyland]

10/10

This is what I listen to the podcast for.

[u/Low-Increase-1192]

Really insightful podcast.

Lex did a great job with the questioning on a topic that required some pretty deep thinking.

Sara’s energy and enthusiasm was infectious. And kudos to her for the lucidity, given how difficult to describe the content must be (as she admitted)

[u/onis_uk]

I found the tempo of her voice so fast I had to slow it down to listen to what she was saying....but then Lex sounded like he was having a stroke 😂

[u/dunnolol123]

I am a little drunk and overall, mostly stupid, but as a rational human being who has just listened to Sara Walker and Lex talk about life for two hours, I have a few thoughts about one of the more fascinating aspects of that talk (they all were awesome, lets be honest); the dark biosphere and why our formulation of entropy may be too anthropomorphic.

Disclaimer: I think I developed a crush with Sara’s mind after this episode. If this beautiful brain doesn’t get a Nobel prize in the future, then to hell with academia.

There are two things Sara mentioned that I want to bring up and derive the rest of this post on; the concept of a dark biosphere and the fact that information is fundamental. The fact that information is the most fundamental thing in our universe is fairly obvious; with a binary operator we are able to get any amount of complexity imaginable. Why not an operator less than two possible states? Well… it does exist, it is the “nothingness” that surrounds our Hubble volume; or multiverse of Hubble volumes, if you choose your epistemic life that way. Not remarkably interesting though, is it?! Given enough time we even get a certain process to turn a binary operator into something that uses base four instead of two; of course, bits are still the subsystem upon which DNA relies upon. It is a neat feature that supersystems can’t exist without subsystems and vice versa.

Life and Information

I will make a very vague definition of life, through the lens of which we can view the following discussion. Life appears to be an agent, or amalgamation of agents, which have a utility function that has a use for a particular arrangement of bits relative to that agent’s goal/s. Everything can be represented in bits, EVERYTHING. Here is the thing though; at a scale of similar agents, the utility function needs a relative translator which is why we have ASCII. It is a universal standard for translating the alphabet into binary. If you don’t speak any human languages though, the bit code that translates “Humans need to be more humble” into binary makes no sense. It may as well translate to glib jobber klamda. What this hints at is that you can take a bit string that is out there in the universe and have vastly different meanings to different agents with different utility functions. To make this more concrete, let us say there is a bit string 01011110001010001111010100 where 1010100 is the bit representation of an apple that is instantiated in the universe. To a human being this bit string has meaning in the sense that I can eat it, which makes it part of my utility function (well, one of them). To a weird gaseous alien that does not need glucose however, that string is gibberish, and the apple does not exist from its xenopomorphic (don’t know if this is a word; anthropomorphic but for aliens) point of view. To this gas creature, the 111100 may be a vital instantiation for it, but be random noise for us (kinda like this ominous substance that 95% of the universe is made of).

Bit-String Intersections

If we take this one step further, we begin to see that the universe is REALLY efficient at getting the most exploration out of a single bit string. Smells like fractality, but that’s a story for another drunk rambling. To make this easier we are going to play physicist and create a nice box with only variables we like and ignore the ones we do not. We assume that only the Earth exists, nothing else; this means the universe’s bit string is just what is going on here. Through the stochastic process we call Natural Selection (henceforth NS) a little utility function finds use for a tiny part of this long bit string. Out of this bit string we get replicators, but not with 100% fidelity which means we get a second replicator that finds use for a slightly different part of the bit string; however, it still shares interest in the bit string from which it sprang. Maybe not all, but some. A billion years later and we are here. Lots of species that each found different uses for different parts of the universal bit string. This is the reason why things from a common ancestor can sense and see each other; they have an overlap in interest relative to the bit string they interact with. As NS selects for more and more traits, we get a larger spectrum of the bit string being utilized and competition increases for similar portions of the same section of this universal bit string. We may think of the intersection as resources needed by competing agents (species).

Dark Biosphere

What does this have to do with the dark biosphere and how can we define it? Strap in ‘cause we are about to speculate. NS is the process that we know of that has a particular attachment to a section of a bitstring and it became really good at occupying it for itself. All of its products interact with each other in the biosphere because they share a common origin point on this bit string. Let us assume now that NS has siblings which occupy a distant part of the bit string; one which has no overlap with that of NS descendants. This would mean that the various agents, which are descendants of this sibling process, share zero bit-string overlap. If that is the case, then nothing descending from NS would know these species exist as there is zero interaction or competition. This could be how Sara’s multiple geneses’ of life events occurred without us knowing. As time increases and the species of each NS like process increases in complexity, we may begin to find more and more life forms on this planet and beyond. Therefore we discover more and more species. When humans had zero utility for parts of the bit string at the Mariana’s Trench, we had no clue about the species of life living down there; once we had utility for that section of the string, we discovered new species of animals. This works for the universe as well. Our sphere moves outward as we occupy and aim to uncover larger parts of the bit string. That is why Greeks had no idea about black holes or neutron stars; there was no connection to the section of the string describing them vs what they knew or cared about. This also explains why we may only now see these TicTac aliens and predicts that we will see more aliens in the universe as we explore more of the bit string and intersect with another agent’s utility function.

[u/noxot]

she had creative ways of looking at things. for there to be a kind of physics to myself is a cool idea. i'm not convinced by some of not having "free will" since thoughts that I have afford me choices. I can see my brain going through a learned suggestion process on what happens to be relevant for me wherein it ask "how about this?" and then "okay then what about this?" and it seems that the brain structures might be shaped as such, though the brain is much more complicated than my simple example. perhaps a better word than free will would be "free choice". obviously the brain makes thinking efficient and the things that fire together are strengthened because they proved useful in the past. so I guess bret weinstein's ideas of consciousness as uncompiled code also comes into play. I think it takes the brain more effort to make choices, it's more efficient to go by what is already ingrained into us.

[u/idunnomysex]

one of the best episodes i've heard, incredibly interesting.

[u/I-make-ada-spaghetti]

Such a fun and interesting podcast.