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Lex Fridman Podcast

#433 – Sara Walker: Physics of Life, Time, Complexity, and Aliens

Thu, 13 Jun 2024

Description

Sara Walker is an astrobiologist and theoretical physicist. She is the author of a new book titled "Life as No One Knows It: The Physics of Life's Emergence". Please support this podcast by checking out our sponsors: - Notion: https://notion.com/lex - Motific: https://motific.ai - Shopify: https://shopify.com/lex to get $1 per month trial - BetterHelp: https://betterhelp.com/lex to get 10% off - AG1: https://drinkag1.com/lex to get 1 month supply of fish oil Transcript: https://lexfridman.com/sara-walker-3-transcript EPISODE LINKS: Sara's Book - Life as No One Knows It: https://amzn.to/3wVmOe1 Sara's X: https://x.com/Sara_Imari Sara's Instagram: https://instagram.com/alien_matter PODCAST INFO: Podcast website: https://lexfridman.com/podcast Apple Podcasts: https://apple.co/2lwqZIr Spotify: https://spoti.fi/2nEwCF8 RSS: https://lexfridman.com/feed/podcast/ YouTube Full Episodes: https://youtube.com/lexfridman YouTube Clips: https://youtube.com/lexclips SUPPORT & CONNECT: - Check out the sponsors above, it's the best way to support this podcast - Support on Patreon: https://www.patreon.com/lexfridman - Twitter: https://twitter.com/lexfridman - Instagram: https://www.instagram.com/lexfridman - LinkedIn: https://www.linkedin.com/in/lexfridman - Facebook: https://www.facebook.com/lexfridman - Medium: https://medium.com/@lexfridman OUTLINE: Here's the timestamps for the episode. On some podcast players you should be able to click the timestamp to jump to that time. (00:00) - Introduction (10:40) - Definition of life (31:18) - Time and space (42:00) - Technosphere (46:25) - Theory of everything (55:06) - Origin of life (1:16:44) - Assembly theory (1:32:58) - Aliens (1:44:48) - Great Perceptual Filter (1:48:45) - Fashion (1:52:47) - Beauty (1:59:08) - Language (2:05:50) - Computation (2:15:37) - Consciousness (2:24:28) - Artificial life (2:48:21) - Free will (2:55:05) - Why anything exists

Audio
Transcription

0.069 - 28.44 Lex Fridman

The following is a conversation with Sarah Walker, her third time on this podcast. She is an astrobiologist and theoretical physicist interested in the origin of life and in discovering alien life on other worlds. She has written an amazing new upcoming book titled Life As No One Knows It, The Physics of Life's Emergence. This book is coming out on August 6th, so please go pre-order it now.

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29.28 - 53.232 Lex Fridman

It will blow your mind. And now a quick few second mention of each sponsor. Check them out in the description. It's the best way to support this podcast. We got Notion for notes, Motific for LLM deployment, Shopify for e-commerce, BetterHelp for mental health, and AG1 for delicious, delicious multivitamin drink. Choose wisely, my friends.

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53.632 - 75.504 Lex Fridman

Also, if you want to get in touch with me or to work with our amazing team, go to lexfreeman.com contact. And now onto the full ad reads. No ads in the middle. I try to make these interesting, but if you skip them, please do check out the sponsors. I enjoy their stuff. Maybe you will too. This episode is brought to you by Notion, a note-taking and team collaboration tool.

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76.185 - 97.741 Lex Fridman

I've been using it recently for note-taking on academic papers, specifically machine learning papers, and there's a lot of machine learning papers. And it's straight up just a great note-taking tool. But beyond that, it's a great collaboration tool for the note-taking process and the whole project management life cycle.

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97.821 - 118.728 Lex Fridman

So it combines note-taking, wikis, project management, and then there's an AI assistant that can summarize everything and anything, and you can ask it questions across all of those things. So it's not just for a single document across all the documents. And obviously people are collaborating on those documents so you can ask questions. What did this person do? What is the status of this project?

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119.288 - 146.575 Lex Fridman

So on, so forth. It's just a really nice integration of LLMs. This is the fundamental question with LLMs. How do you leverage the obvious power that they possess to be useful? to whatever tasks that we do. Like what is the actual product here? And so Notion leverages them extremely well where the product is team collaboration on notes, wikis, and project management. So really well done.

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147.315 - 165.43 Lex Fridman

Love to support people that do a great job of building a great software product. Try Notion AI for free when you go to notion.com slash lex. That's all lowercase, notion.com slash lex to try the power of Notion AI today. This episode is brought to you by a new sponsor, Motific.

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165.81 - 188.032 Lex Fridman

It's a SaaS platform that helps businesses deploy LLMs and, in general, generative AI that are customized with RAG, retrieval augmented generation, on organizational data sources. Obviously, these kinds of data sources are often super sensitive, and that's where Motific comes in. They help companies with security and compliance.

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188.513 - 212.83 Lex Fridman

A little background here, since I had to do the deep dive myself a while back. Motific is created by Cisco, specifically Cisco's OutShift group. And OutShift is doing cutting-edge R&D stuff in Cisco. So, Cisco has... very, very, very long track record and reputation of working with giant businesses and helping them out and not messing stuff up.

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213.73 - 232.32 Lex Fridman

When you're dealing with sensitive data and when you're dealing with businesses that make a lot of money and already have products that bring in a lot of money and a lot of people rely on, you don't want to mess stuff up. I think specifically this task of taking organizational data

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233.16 - 264.897 Lex Fridman

that's private to the company, that has to remain very secure, it's very sensitive data, using the power of LLMs and search via the RAG framework on that data is super, super powerful. I think companies that do this well and quickly, which is what Modific helps with, will win because the productivity gains, nobody knows, but I don't think there's a ceiling.

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265.217 - 293.181 Lex Fridman

So it pays us off to play with LLMs, but do so in a secure way. Visit Motific AI to learn more. That's M-O-T-I-F-I-C dot A-I. This episode is also brought to you by Shopify, a platform designed for anyone to sell anywhere with a great-looking online store. I have a site set up, blackstreamer.com. It has a few shirts on it. It took a few minutes to set up. Super easy.

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293.501 - 315.207 Lex Fridman

They integrate third-party apps. I did that for the on-demand printing, so I don't have to think about any of that. All you do is upload the design. The shirts are sold and shipped. It's kind of an interesting experiment for me. to understand how people look at you when you have a t-shirt with nothing on it and a t-shirt with something on it, especially if that something is recognizable.

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315.507 - 334.765 Lex Fridman

So if I have a Jimi Hendrix or Pink Floyd shirt or Johnny Cash or Metallica shirt, there's going to be certain people that look at me with recognition and respect and almost like they want to start a conversation with me. When I have a t-shirt, like a black t-shirt with nothing on it, That kind of look doesn't happen.

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335.085 - 357.541 Lex Fridman

If I went out more, I would take a notebook and actually make this a little bit more rigorous. But anyway, there's definitely a noticeable social effect that happens when you have a t-shirt with a cool thing on it. So I'm really happy with all the creators that are using Shopify to sell cool t-shirts. I wish there was a better discovery process, though. I'm always in search of buying...

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358.439 - 383.896 Lex Fridman

Cool t-shirts. I just, on Instagram, I think, there was an advertisement for a set of t-shirts for classic movies. And that was really badass, but I scrolled past it. And I regret it. See, that's like a piece of advertisement that actually works. but I wish there was a way to not take me from the scrolling experience or maybe a way to bookmark it really naturally.

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384.276 - 408.367 Lex Fridman

There's already a natural sort of skepticism about advertisement, but here it worked. So like when advertisement is done well, it works. I just wish I saved it. But anyway, hopefully they use Shopify to sell shirts. If they don't, they should. And if you're thinking of selling shirts, use Shopify also. Sign up for a $1 per month trial period at shopify.com slash lux. That's all lowercase.

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408.847 - 433.347 Lex Fridman

Go to shopify.com slash lux to take your business to the next level today. This episode is brought to you by BetterHelp, spelled H-E-L-P, help. They figure out what you need to match you with a licensed therapist in under 48 hours. Individuals, couples, the whole thing. What are my favorite couples therapies in film? I feel like Breaking Bad had good ones.

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434.327 - 459.859 Lex Fridman

That's a series, but I'm trying to think of a movie. That's a cool setting because I've been thinking about interviewing directors and actors more and more. And the setting of a couple's therapy is really interesting. It's a really interesting dynamic between a man, a woman, and a therapist. And them trying to sort of make explicit the implicit drama that's been boiling over in their relationship.

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460.379 - 486.584 Lex Fridman

Obviously, the therapist one-on-one relationship is really interesting on film. Good Will Hunting with Robin Williams. Man, what a great, great performance. I miss that guy so much. What a truly special human being. Anyway, back in the real world, therapy, even when there's no camera, is really important for shining the light on the Jungian shadow.

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486.604 - 513.262 Lex Fridman

350 million plus messages, 34,000 licensed therapists, 4.4 million people who have gotten help through BetterHelp. Check them out at betterhelp.com and save on your first month. That's betterhelp.com. This episode is also brought to you by AG1, an all-in-one daily drink to support better health and peak performance. I drink it every day, multiple times a day, sometimes.

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514.183 - 531.099 Lex Fridman

Usually after a run, like I'm going to go for a run in a little bit. It's already that Texas heat. It's warming up. It's warming up. It's creeping up in the 100 degree weather. And I love it. I don't care. The hotter it is, the tougher the run, the more of a mental test it is.

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531.7 - 554.362 Lex Fridman

And what I do is I speed up, take that feeling of discomfort, and allow myself to sit in it and visualize that feeling of discomfort fading. So from a third person perspective, it's just a feeling. And a feeling can be controlled. A feeling can be ignored. A feeling can be morphed from the negative to the positive.

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555.123 - 579.325 Lex Fridman

So for me, it's not just a meditative practice of letting go of all feelings and focusing on the breath. For me, it is also being able to control that discomfort and letting go of that discomfort, the feeling and the notion of discomfort, even when on the surface there should be a lot of physical discomfort because physical discomfort is first and foremost a construction of the mind.

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579.365 - 607.688 Lex Fridman

It's not real. It's not real. As long as you believe it's not real, it's not real. And that's what I do. But when I get back home extremely exhausted and uncomfortable, having overcome that challenge, I put an AG1 in the freezer for like 30 minutes. It has this great consistency. And then after a shower, I just take the drink and celebrate having overcome something difficult.

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608.448 - 650.94 Lex Fridman

They'll give you one month's supply of fish oil when you sign up at drinkag1.com slash Lex. This is the Lex Freeman Podcast. To support it, please check out our sponsors in the description. And now, dear friends, here's Sarah Walker. You open the book, Life as No One Knows It, The Physics of Life's Emergence, with a distinction between the materialists and the vitalists. So what's the difference?

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651.4 - 652.481 Lex Fridman

Can you maybe define the two?

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652.961 - 683.866 Sarah Walker

I think the question there is about whether life can be described in terms of matter and physical things, or whether there is some Other feature that's not physical that actually animates living things. So for a long time, people maybe have called that a soul. It's been really hard to pin down what that is. So I think the vitalist idea is really that it's kind of a dualistic interpretation.

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684.546 - 703.04 Sarah Walker

That there's sort of the material properties, but there's something else that animates life that is there when you're alive and it's not there when you're dead. And materialists kind of don't think that there's anything really special about the matter of life and the material substrates that life is made out of. So they disagree on some really fundamental points.

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703.823 - 728.583 Lex Fridman

Is there a gray area between the two? Maybe all there is is matter, but there's so much we don't know that it might as well be magic, whatever that magic that the vitalists see. Meaning there's just so much mystery that it's really unfair to say that it's boring and understood and as simple as, quote unquote, physics.

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729.403 - 754.59 Sarah Walker

Yeah, I think the entire universe is just a giant mystery. I guess that's what motivates me as a scientist. And so oftentimes when I look at open problems like the nature of life or consciousness or what is intelligence or are there souls or whatever question that we have that we feel like we aren't even on the tip of answering yet, I think we have a lot more work to do to really understand that.

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755.131 - 779.229 Sarah Walker

the answers to these questions. So it's not magic, it's just the unknown. And I think a lot of the history of humans coming to understand the world around us has been taking ideas that we once thought were magic or supernatural and really understanding them in a much deeper way that we learn what those things are. And they still have an air of mystery even when we understand them.

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779.469 - 783.312 Sarah Walker

There's no sort of bottom to our understanding.

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784.042 - 791.687 Lex Fridman

So do you think the vitalists have a point that they're more eager and able to notice the magic of life?

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792.648 - 809.16 Sarah Walker

I think that no tradition, vitalists included, is ever fully wrong about the nature of the things that they're describing. So a lot of times when I look at different ways that people have described things across human history, across different cultures, there's always a seed of truth in them.

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809.36 - 830.136 Sarah Walker

And I think it's really important to try to look for those because if there are narratives that humans have been telling ourselves for thousands of years, for thousands of generations, there must be some truth to them. We've been learning about reality for a really long time, and we recognize the patterns that reality presents us. We don't always understand what those patterns are.

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830.854 - 847.418 Sarah Walker

And so I think it's really important to pay attention to that. So I don't think the vitalists were actually wrong. And a lot of what I talk about in the book, but also I think about a lot just professionally, is the nature of our definitions of what's material and how science has come to invent the concept of matter.

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848.018 - 862.194 Sarah Walker

And that some of those things actually really are inventions that happened in a particular time in a particular technology that could learn about certain patterns. and help us understand them. And that there are some patterns we still don't understand.

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862.974 - 885.76 Sarah Walker

And if we knew how to measure those things, or we knew how to describe them in a more rigorous way, we would realize that the material world matter has more properties than we thought that it did. And one of those might be associated with the thing that we call life. Life could be a material property and still have a lot of the features that the vitalists thought were mysterious.

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886.417 - 898.663 Lex Fridman

So we may still expand our understanding what is incorporated in the category of matter that will eventually incorporate such magical things that the vitalists have noticed like life.

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899.283 - 919.159 Sarah Walker

Yeah. So I think about, I always like to use examples from physics, so I'll probably do that. It's just my go-to place. But in the history of gravitational physics, for example, in the history of motion, when Aristotle came up with his theories of motion, he did it by the material properties he thought things had.

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919.259 - 929.328 Sarah Walker

So there was a concept of things falling to Earth because they were solid-like and things raising to the heavens because they were air-like and things moving around the planet because they were celestial-like.

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929.977 - 953.19 Sarah Walker

But then we came to realize that thousands of years later and after the invention of many technologies that allowed us to actually measure time in a mechanistic way and track planetary motion, and we could roll balls down inclined planes and track that progress, we realized that if we just talked about mass and acceleration, we could unify all motion in the universe.

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953.77 - 973.316 Sarah Walker

in a really simple description. So we didn't really have to worry about the fact that my cup is heavy and the air is light. The same laws describe them if we have the right material properties to talk about what those laws are actually interacting with. And so I think the issue with life is we don't know how to think about information in a material way.

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974.016 - 986.823 Sarah Walker

And so we haven't been able to build a unified description of what life is or the kind of things that Evolution builds because we haven't really invented the right material concept yet.

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987.603 - 1001.995 Lex Fridman

So when talking about motion, the laws of physics appear to be the same everywhere in the universe. Do you think the same is true for other kinds of matter that we might eventually include life in?

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1003.402 - 1020.748 Sarah Walker

I think life obeys universal principles. I think there is some deep underlying explanatory framework that will tell us about the nature of life in the universe and will allow us to identify life that we can't yet recognize because it's too different.

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1021.729 - 1028.151 Lex Fridman

You write about the paradox of defining life. Why does it seem to be so easy and so complicated at the same time?

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1028.766 - 1047.892 Sarah Walker

You know, all the sort of classic definitions people want to use just don't work. They don't work in all cases. So Carl Sagan had this wonderful essay on definitions of life where I think he talks about aliens coming from another planet. If they saw Earth, they might think that cars were the dominant life form because there's so many of them on our planet.

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1048.7 - 1067.592 Sarah Walker

And like humans are inside them and you might want to exclude machines. But any definition, you know, like classic biology textbook definitions would also include them. And so, you know, he wanted to draw a boundary between these kind of things by trying to exclude them. But they were naturally included by the definitions people want to give.

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1067.612 - 1087.493 Sarah Walker

And in fact, what he ended up pointing out is that all of the definitions of life that we have, whether it's life as a self-reproducing system or life eats to survive or life requires compartments, whatever it is, there's always a counter example that challenges that definition. This is why viruses are so hard or why fire is so hard.

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1088.133 - 1095.476 Sarah Walker

And so we've had a really hard time trying to pin down from a definitional perspective exactly what life is.

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1096.129 - 1107.139 Lex Fridman

Yeah, you actually bring up the zombie ant fungus. I enjoyed looking at this thing as an example of one of the challenges. You mentioned viruses, but this is a parasite. Look at that.

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1107.699 - 1108.76 Sarah Walker

Did you see this in the jungle?

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1109.02 - 1138.481 Lex Fridman

Infects ants. Actually, one of the interesting things about the jungle, everything is ephemeral. Everything eats everything really quickly. So if an organism dies, that organism disappears. Yeah. It's a machine that doesn't have, I wanted to say it doesn't have a memory or a history, which is interesting given your work on history in defining a living being. The jungle forgets very quickly.

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1138.501 - 1141.903 Lex Fridman

It wants to erase the fact that you existed very quickly.

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1141.943 - 1165.289 Sarah Walker

Yeah, but it can't erase it. It's just restructuring it. And I think the other thing that is really vivid to me about this example that you're giving is how much death is necessary for life. So I worry a bit about notions of immortality and whether immortality is a good thing or not. So I have sort of a broad conception that life is the only thing the universe

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1165.969 - 1184.205 Sarah Walker

generates that actually has even the potential to be immortal. But that's as like this sort of process that you're describing where life is about memory and historical contingency and construction of new possibilities. But when you look at any instance of life, especially one as dynamic as what you're describing, it's a constant birth and death process.

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1184.625 - 1207.85 Sarah Walker

But that birth and death process is like the way that the universe can explore what possibilities can exist and Not everything, not every possible human or every possible ant or every possible zombie ant or every possible tree will ever live. So it's, you know, it's an incredibly dynamic and creative place because of all that death.

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1208.373 - 1232.643 Lex Fridman

So does this thing, this is a parasite that needs the ant. So is this a living thing or is this not a living thing? So this is... Yeah, so... It just pierces the ant. I mean, it... Right. And I've seen a lot of this, by the way. Organisms working together in the jungle, like ants protecting a delicious piece of fruit. So they need the fruit, but if you touch that fruit, they're going to...

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1233.143 - 1241.768 Lex Fridman

Like, the forces emerge. They're fighting you. They're defending that food to the death. It's just nature seems to find mutual benefits, right?

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1242.609 - 1260.259 Sarah Walker

Yeah, it does. I think the thing that's perplexing for me about these kind of examples is, you know, effectively the ant's dead, but it's staying alive now because it's piloted by this fungus. And so that gets back to this, you know— thing that we were talking about a few minutes ago about how the boundary of life is really hard to define.

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1260.399 - 1273.104 Sarah Walker

So, you know, anytime that you want to draw a boundary around something and you say, this feature is the thing that makes this alive, or this thing is alive on its own, there's not ever really a clear boundary.

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1273.124 - 1292.191 Sarah Walker

And these kind of examples are really good at showing that because it's like the thing that you would have thought is the living organism is now dead, except that it has another living organism that's piloting it. So the two of them together are are alive in some sense, but they're, you know, now in this kind of weird symbiotic relationship that's taking the sand to its death.

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1292.711 - 1295.692 Lex Fridman

So what do you do with that in terms of when you try to define life?

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1296.352 - 1320.155 Sarah Walker

I think we have to get rid of the notion of an individual as being relevant. And this is really difficult because, you know, a lot of the ways that we think about life, like the fundamental unit of life is the cell. Individuals are alive. But we don't think about how how gray that distinction is. So, for example, you might consider

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1320.933 - 1338.962 Sarah Walker

you know, self-reproduction to be the most defining feature of life. A lot of people do actually like, you know, one of these standard different definitions that a lot of people may feel like to use in astrobiology is life as a self-sustaining chemical system capable of Darwinian evolution, which I was once quoted as agreeing with. And I was really offended because I hate that definition.

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1338.982 - 1345.565 Sarah Walker

I think it's terrible. And I think it's terrible that people use it. I think like every word in that definition is actually wrong as a descriptor of life.

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1346.016 - 1351.441 Lex Fridman

Life is a self-sustaining chemical system capable of Darwinian evolution. Why is that? That seems like a pretty good definition.

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1351.461 - 1355.806 Sarah Walker

Yeah, I know. If you want to make me angry, you can pretend I said that and believed it.

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1356.406 - 1368.458 Lex Fridman

So self-sustaining, uh, chemical system, Darwinian evolution. What is self-sustaining? What's, what, what's so frustrating? I mean, which aspect is frustrating to you, but it's also those are very interesting words.

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1368.758 - 1388.987 Sarah Walker

Yeah, they're all interesting words. Um, And, you know, together they sound really smart and they sound like they box in what life is, but you can use any of the words individually and you can come up with counterexamples that don't fulfill that property. The self-sustaining one is really interesting thinking about humans, right? Like we're not self-sustaining. We're dependent on societies.

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1389.667 - 1411.681 Sarah Walker

And so, you know, I find it paradoxical that, you know, it might be that societies, because they're self-sustaining units, are now more alive than individuals are. And that could be the case, but I still think we have some property associated with life. I mean, that's the thing that we're trying to describe. So that one's quite hard. And in general, you know, no organism is really self-sustaining.

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1411.721 - 1435.792 Sarah Walker

They always require an environment. So being self-sustaining is coupled in some sense to the world around you. We don't live in a vacuum. So that part's already challenging. And then you can go to chemical system. I don't think that's good either. I think there's a confusion because life emerges in chemistry, that life is chemical. I don't think life is chemical.

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1435.912 - 1446.762 Sarah Walker

I think life emerges in chemistry because chemistry is the first thing the universe builds where it cannot exhaust all the possibilities because the combinatorial space of chemistry is too large.

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1447.113 - 1449.756 Lex Fridman

Well, but is it possible to have a life that is not a chemical system?

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1450.016 - 1450.216 Sarah Walker

Yes.

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1450.937 - 1462.588 Lex Fridman

There's a guy I know named Lee Cronin who's been on a podcast a couple of times who just got really pissed off listening to this. He probably just got really pissed off hearing that. For people who somehow don't know he's a chemist.

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1462.908 - 1464.43 Lee Cronin

Yeah, but he would agree with that statement.

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1464.947 - 1471.538 Lex Fridman

Would he? I don't think he would. I don't think he would. He would broaden the definition of chemistry until it would include everything.

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1471.638 - 1474.123 Sarah Walker

Oh, sure. Or maybe. I don't know.

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1474.163 - 1477.929 Lex Fridman

But wait, but you said that universe, that's the first thing it creates is chemistry.

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1478.416 - 1500.111 Sarah Walker

Where the – very precisely, it's not the first thing it creates. Obviously, like, it has to make atoms first. But it's the first thing. Like, if you think about, you know, the universe originated, atoms were made in, you know, Big Bang nuclear synthesis and then later in stars and then planets formed and planets become engines of chemistry. They start exploring what kind of chemistry is possible.

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1500.131 - 1523.172 Sarah Walker

Okay. And the combinatorial space of chemistry is so large that even on every planet in the entire universe, you will never express every possible molecule. I like this example actually that Lee gave me, which is to think about taxol. It has a molecular weight of about It's got, you know, a lot of atoms, but it's not astronomically large.

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1523.672 - 1544.668 Sarah Walker

And if you tried to make one molecule with that molecular formula and every three-dimensional shape you could make with that molecular formula, it would fill 1.5 universes. So with one unique molecule. That's just one molecule. So chemical space is huge.

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1546.008 - 1564.36 Sarah Walker

And I think it's really important to recognize that because if you want to ask a question of why does life emerge in chemistry, well, life emerges in chemistry because life is the physics of how the universe selects what gets to exist. And those things get created along historically contingent pathways and memory and all the other stuff that we can talk about.

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1565.421 - 1571.606 Sarah Walker

But the universe has to actually make historically contingent choices in chemistry because it can't exhaust all possible molecules.

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1571.786 - 1578.452 Lex Fridman

What kind of things can you create that's outside the combinatorial space of chemistry? That's what I'm trying to understand.

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1578.772 - 1600.692 Sarah Walker

Oh, if it's not chemical. So I think some of the things that have evolved on our biosphere, I would call as much alive... as chemistry, as a cell, but they seem much more abstract. So for example, I think language is alive, I think, or at least life. I think memes are, I think- You're saying language is life.

0
💬 0

1601.213 - 1604.877 Lex Fridman

Yes. Language is alive. Oh boy, I'm gonna have to explore that one.

0
💬 0

1606.599 - 1628.075 Sarah Walker

Life maybe not, maybe not alive, but I don't, I actually don't know where I stand exactly on that. I've been thinking about that a little bit more lately, but mathematics too. And it's interesting because people think that math has this platonic reality that exists outside of our universe. And I think it's a feature of our biosphere and it's telling us something about the structure of ourselves.

0
💬 0

1629.516 - 1645.122 Sarah Walker

And I find that really interesting because when you would sort of internalize all of these things that we noticed about the world and you start asking, well, what did these look like if I was, you know, something outside of myself observing these systems that we're all embedded in, what would that structure look like?

0
💬 0

1645.222 - 1650.164 Sarah Walker

And I think we look really different than the way that we talk about what we look like to each other. Yeah.

0
💬 0

1650.592 - 1657.099 Lex Fridman

What do you think a living organism in math is? Is it one axiomatic system or is it individual theorems?

0
💬 0

1657.239 - 1685.524 Sarah Walker

I think it's the fact that it's open-ended in some sense. It's another open-ended combinatorial space and the recursive properties of it allow creativity to happen. which is what you see with the revolution in the last century with Gödel's theorem and Turing. And there's clear places where mathematics notices holes in the universe.

0
💬 0

1686.285 - 1692.289 Lex Fridman

So it seems like you're sneaking up on a different kind of definition of life, open-ended, large combinatorial space.

0
💬 0

1692.95 - 1693.21 Sarah Walker

Yeah.

0
💬 0

1693.737 - 1694.757 Lex Fridman

Room for creativity.

0
💬 0

1694.898 - 1698.919 Sarah Walker

Definitely not chemical. I mean, chemistry is one substrate.

0
💬 0

1698.939 - 1708.043 Lex Fridman

Restricted to chemical. Yeah. Chemical. Okay, what about the third thing, which I think will be the hardest because you probably like it the most, is evolution or selection?

0
💬 0

1708.283 - 1710.204 Sarah Walker

Well, specifically it's Darwinian evolution.

0
💬 0

1710.224 - 1710.684 Lex Fridman

Darwinian, okay.

0
💬 0

1710.944 - 1725.875 Sarah Walker

And I think Darwinian evolution is a problem, but the reason that that definition is a problem is not because evolution is in the definition, but because the implication is that evolution you know, that most people would want to make is that an individual is alive.

0
💬 0

1726.496 - 1745.981 Sarah Walker

And the evolutionary process, at least the Darwinian evolutionary process, most evolutionary processes, they don't happen at the level of individuals. They happen at the level of populations. So again, you would be saying something like what we saw with the self-sustaining definition, which is that populations are alive, but individuals aren't because populations evolve and individuals don't.

0
💬 0

1746.381 - 1763.596 Sarah Walker

And obviously, maybe you're alive because your gut microbiome is evolving, but Lex as an entity right now is not evolving by canonical theories of evolution. In assembly theory, which is attempting to explain life, evolution is a much broader thing. So

0
💬 0

1764.156 - 1767.561 Lex Fridman

So then an individual organism can evolve under assembly theory?

0
💬 0

1767.962 - 1774.031 Sarah Walker

Yes. You're constructing yourself all the time. Assembly theory is about construction and how the universe selects for things to exist.

0
💬 0

1774.571 - 1777.896 Lex Fridman

What if you were to formulate everything like a population is a living organism?

0
💬 0

1778.157 - 1789.645 Sarah Walker

That's fine too. But, but this again gets back to, so, um, so I think what all of the, you know, like we can nitpick at definitions. I don't think it's like incredibly helpful to do it, but the reason for, for me.

0
💬 0
0
💬 0

1790.225 - 1813.236 Sarah Walker

Yeah, it is fun. It is really fun. And actually I do, I do think it's useful in the sense that when you see the way, the you either have to keep forcing in your like sort of conception of life you want to have, or you have to say, all these definitions are breaking down for a reason. Maybe I should adopt a more expansive definition that encompasses all the things that I think and our life.

0
💬 0

1813.356 - 1841.048 Sarah Walker

And so for me, I think life is the process of how information structures matter over time and space. And an example of life is what emerges on a planet and, you know, yields an open-ended cascade of generation of structure and increasing complexity. And this is the thing that life is. And any individual is just a particular instance of these lineages that are, you know, structured across time.

0
💬 0

1842.209 - 1861.449 Sarah Walker

And so we focus so much on these individuals that are these short temporal moments in this larger causal structure that actually is the life on our planet. And I think that's why these definitions break down because they're not general enough. They're not universal enough. They're not deep enough. They're not abstract enough to actually capture that regularity.

0
💬 0

1861.769 - 1866.211 Lex Fridman

Because we're focused on that little ephemeral thing that we call human life.

0
💬 0

1866.231 - 1877.476 Sarah Walker

Yeah, it's like Aristotle focusing on heavy things falling because they're earth-like and things floating because they're air-like. It's the wrong thing to focus on.

0
💬 0

1878.916 - 1883.198 Lex Fridman

What exactly are we missing by focusing on such a short span of time?

0
💬 0

1884.018 - 1899.165 Sarah Walker

I think we're missing most of what we are. So one of the issues, I've been thinking about this really viscerally lately. It's weird when you do theoretical physics because I think it literally changes the structure of your brain and you see the world differently, especially when you're trying to build new abstractions.

0
💬 0

1899.325 - 1906.128 Lex Fridman

Do you think it's possible if you're a theoretical physicist that it's easy to fall off the cliff and go descend into madness?

0
💬 0

1906.704 - 1926.965 Sarah Walker

I mean, I think you're always on the edge of it, but I think what is amazing about being a scientist and trying to do things rigorously is it keeps your sanity. So I think if I wasn't a theoretical physicist, I would be probably not sane. But what it forces you to do is hold the fire, like you have to hold yourself to the fire of like,

0
💬 0

1927.423 - 1944.936 Sarah Walker

these abstractions in my mind have to really correspond to reality. And I have to really test that all the time. And so I love building new abstractions and I love going to those like incredibly creative, you know, spaces that people don't see as part of the way that we understand the world now.

0
💬 0

1945.196 - 1954.683 Sarah Walker

But ultimately I have to make sure that whatever I'm pulling from that space is something that's really usable and really like relates to the world outside of me. That's what science is.

0
💬 0

1955.123 - 1962.486 Lex Fridman

So we were talking about what we're missing when we look at a small stretch of time and a small stretch of space.

0
💬 0

1963.046 - 1983.593 Sarah Walker

Yeah. So the issue is we evolve perception to see reality a certain way, right? So for us, space is really important and time feels fleeting. And I had a really wonderful mentor, Paul Davies, most of my career. And Paul's amazing because he gives these like little seed thought experiments all the time.

0
💬 0

1983.653 - 1998.459 Sarah Walker

Like, you know, something he used to ask me all the time was when I was a postdoc, this is kind of a random tangent, but was like, you know, how much of the universe could be converted into technology if you were thinking about like, you know, long-term futures and stuff like that. And it's like a weird thought experiment, but like there's a lot of deep things there.

0
💬 0

1998.479 - 2017.784 Sarah Walker

And I do think a lot about the fact that We're really limited in our interactions with reality by the particular architectures that we evolved. And so we're not seeing everything. And in fact, our technology tells us this all the time because it allows us to see the world in new ways by basically allowing us to perceive the world in ways that we couldn't otherwise.

0
💬 0

2018.665 - 2036.82 Sarah Walker

And so what I'm getting at with this is I think that living objects are actually huge. Like they're some of the biggest structures in the universe, but but they are not big in space, they are big in time. And we actually can't resolve that feature. We don't interact with it on a regular basis.

0
💬 0

2036.86 - 2048.764 Sarah Walker

So we see them as these fleeting things that have this really short temporal clock time without seeing how large they are. When I'm saying time here, I really like the way that people could picture it is in terms of causal structure.

0
💬 0

2048.824 - 2061.788 Sarah Walker

So if you think about the history of the universe to get to you and you imagine that that entire history is you, that is the picture I have in my mind when I look at every living thing.

0
💬 0

2062.418 - 2066.78 Lex Fridman

So you have a tweet for everything. You tweeted.

0
💬 0

2066.82 - 2067.441 Sarah Walker

Doesn't everyone?

0
💬 0

2068.161 - 2076.326 Lex Fridman

You have a lot of poetic, profound tweets. Sometimes they're puzzles that take a long time to figure out.

0
💬 0

2076.366 - 2087.212 Sarah Walker

Well, you know what the trick is? The reason they're hard to write is because it's compressing a very deep idea into a short amount of space. And I really like doing that intellectual exercise because I find it productive for me.

0
💬 0

2087.714 - 2091.178 Lex Fridman

Yeah, it's a very interesting kind of compression algorithm, though.

0
💬 0

2091.498 - 2093.501 Sarah Walker

Yeah, I like language. I think it's really fun to play with.

0
💬 0

2093.521 - 2096.904 Lex Fridman

Yeah, I wonder if AI can decompress it.

0
💬 0

2097.885 - 2109.138 Sarah Walker

I would like to try this, but I think I use language in certain ways that are non-canonical, and I do it very purposefully. And it would be interesting to me how AI would interpret it.

0
💬 0

2109.178 - 2141.567 Lex Fridman

Yeah, your tweets would be a good Turing test for super intelligence. Anyway, you tweeted that things only look emergent because we can't see time. So if we could see time, what would the world look like? You're saying you'll be able to see everything that an object has been every step of the way that led to this current moment. And all the interactions that require to make that evolution happen.

0
💬 0

2142.007 - 2143.969 Lex Fridman

You would see this gigantic tail.

0
💬 0

2144.529 - 2148.973 Sarah Walker

The universe is far larger in time than it is in space.

0
💬 0

2149.513 - 2149.913 Lex Fridman

Yeah.

0
💬 0

2150.594 - 2154.657 Sarah Walker

And this planet is one of the biggest things in the universe.

0
💬 0

2155.578 - 2157.92 Lex Fridman

Oh, so the more complexity, the bigger. Yeah.

0
💬 0

2159.441 - 2165.586 Sarah Walker

Technosphere. I think the modern technosphere is the largest object in time in the universe that we know about.

0
💬 0

2166.656 - 2169.178 Lex Fridman

And when you say technosphere, what do you mean?

0
💬 0

2169.198 - 2173.78 Sarah Walker

I mean the global integration of life and technology on this planet.

0
💬 0

2174.221 - 2176.682 Lex Fridman

So all the things, all the technological things we've created?

0
💬 0

2177.663 - 2193.678 Sarah Walker

But I don't think of them as separate. They're like very integrated with the structure that generated them. So you can almost imagine it like time is constantly bifurcating and it's generating new structures. And these new structures are, you know, locally constructing the future.

0
💬 0

2194.219 - 2207.419 Sarah Walker

And so things like you and I are very close together in time because we didn't diverge like very early in the history universe. It's very recent. And I think this is one of the reasons that we can understand each other so well and we can communicate effectively.

0
💬 0

2208.239 - 2234.555 Sarah Walker

And I might have some sense of what it feels like to be you, but other organisms bifurcated from us in time earlier, this is just the concept of phylogeny, right? But if you take that deeper and you really think about that as the structure of the physics that generates life, and you take that very seriously, all of that causation is still bundled up Uh, yeah.

0
💬 0

2255.515 - 2274.689 Sarah Walker

It's hard to use words to visualize what's in minds. I have such a hard time with this sometimes. Actually, I was thinking in the way over here. I was like, you know, you have pictures in your brain, and then they're hard to put into words. But I realized I always say I have a visual, but it's not actually I have a visual. It's I have a feeling.

0
💬 0

2274.709 - 2286.934 Sarah Walker

Because oftentimes I cannot actually draw a picture in my mind. for the things that I say, but sometimes they go through a picture before they get to words. But I like experimenting with words because I think they help paint pictures.

0
💬 0

2287.295 - 2311.278 Lex Fridman

Yeah, it's again, some kind of compressed feeling that you can query to get a sense of the bigger visualization that you have in mind. It's just a really nice compression. But I think the idea of this object that in it contains all the information about the history of an entity that you see now, just trying to visualize that is pretty cool.

0
💬 0
0
💬 0

2312.419 - 2318.945 Lex Fridman

I mean, obviously the mind breaks down quickly as you step seconds and minutes back in time.

0
💬 0

2319.526 - 2320.227

Yeah, for sure.

0
💬 0

2321.728 - 2328.426 Lex Fridman

I guess it's just a gigantic thing. Yeah. We're supposed to be thinking about.

0
💬 0

2328.586 - 2342.698 Sarah Walker

Yeah, I think so. And I think this is one of the reasons that we have such an ability to abstract as humans because we are so gigantic that like the space that we can go back into is really large. So like the more abstract you're going, like the deeper you're going in that space.

0
💬 0

2343.078 - 2346.141 Lex Fridman

But in that sense, aren't we fundamentally all connected?

0
💬 0

2346.781 - 2354.908 Sarah Walker

Yes. And this is why the definition of life cannot be the individual. It has to be these lineages because they're all connected. They're interwoven and they're exchanging parts all the time.

0
💬 0

2355.56 - 2369.028 Lex Fridman

Yeah, so maybe there's certain aspects of those lineages that can be lifelike. They can be characteristics. They can be measured like with the assembly theory that have more or less life. But they're all just fingertips of a much bigger object.

0
💬 0

2370.731 - 2394.497 Sarah Walker

Yeah, I think life is very high dimensional. And in fact, I think you can be alive in some dimensions and not in others. Like if you could project all the causation that's in you, in some features of you, you know, very little causation is required and like very little history. And in some features, a lot is. So it's quite difficult to take this really high dimensional perspective.

0
💬 0

2395.037 - 2405.841 Sarah Walker

very deep structure and project it into things that we really can understand and say like this is the one thing that we're seeing because it's not one thing.

0
💬 0

2407.021 - 2433.444 Lex Fridman

It's funny we're talking about this now and I'm slowly starting to realize one of the things I saw when I took ayahuasca afterwards actually so the actual ceremony is four or five hours but afterwards you're still riding whatever the thing that you're riding and I I got a chance to afterwards hang out with some friends and just shoot the shit in the forest. And I get to see their faces.

0
💬 0

2435.285 - 2451.091 Lex Fridman

And what was happening with their faces and their hair is I would get this interesting effect. First of all, everything was beautiful and I just had so much love for everybody. I could see their past selves like behind them.

0
💬 0

2451.191 - 2478.466 Lex Fridman

It was this effect where I guess it's a blurring effect of where like if I move like this, the faces that were just there are still there and it would just float like this, these behind them, which will create this incredible effect. But it's also another way to think about that is I'm visualizing a little bit of that object, of the thing they wore just a few seconds ago.

0
💬 0

2478.486 - 2506.988 Lex Fridman

It's a cool little effect. And now it's like giving it a bit more profundity to the effect that was just beautiful aesthetically, but it's also beautiful from a physics perspective because that is a past self. I get a little glimpse at the past selves that they were, but then you take that, to its natural conclusion, not just a few seconds ago, but just to the beginning of the universe.

0
💬 0

2507.028 - 2508.268 Lex Fridman

And you could probably get to that.

0
💬 0

2508.288 - 2509.069 Sarah Walker

Billions of years, yeah.

0
💬 0

2509.249 - 2510.429 Lex Fridman

Get down that lineage.

0
💬 0

2511.029 - 2513.71 Sarah Walker

It's crazy that there's billions of years inside all of us.

0
💬 0

2513.83 - 2518.732 Lex Fridman

All of us. Yeah. And then we connect, obviously. Yeah. Not too long ago.

0
💬 0
0
💬 0

2520.828 - 2531.942 Lex Fridman

You mentioned just the technosphere, and you also wrote that the most alive thing on this planet is our technosphere. Why is the technology we create a kind of life form? Why are you seeing it as life?

0
💬 0

2532.987 - 2556.809 Sarah Walker

Because it's creative, but with us, obviously, like not independently of us. And also because of this sort of lineage view of life. And I think about life often as a planetary scale phenomena, because that's sort of the natural boundary for all of this causation that's bundled in every object in our biosphere. And so for me, it's just sort of the current boundary of how far life

0
💬 0

2558.334 - 2581.131 Sarah Walker

on our planet has pushed into the things that our universe can generate. And so it's the furthest thing. It's the biggest thing. And I think a lot about the nature of life across different scales. And so, you know, we have cells inside of us that are alive and we feel like we're alive, but we don't often think about the societies that we're embedded in.

0
💬 0

2581.88 - 2599.726 Sarah Walker

as alive or a global scale organization of us and our technology on the planet as alive. But I think if you have this deeper view into the nature of life, which I think is necessary also to solve the origin of life, then you have to include those things.

0
💬 0

2600.706 - 2608.832 Lex Fridman

All of them. So you have to simultaneously think about life at every single scale. The planetary and the bacteria level.

0
💬 0

2609.092 - 2625.464 Sarah Walker

Yeah. This is the hard thing about solving the problem of life, I think, is how many things you have to integrate into building a unified picture of this thing that we want to call life. And a lot of our theories of physics are built on building...

0
💬 0

2626.485 - 2652.712 Sarah Walker

deep regularities that explain a really broad class of phenomenon i think we haven't really traditionally thought about life that way uh but i think to get it at some of these hardest questions like looking for life on other planets or the original life you really have to think about it that way and so most of like my professional work is just trying to understand like every single thing on this planet that might be an example of life which is pretty much everything and then trying to figure out like what's the deeper structure underlying that

0
💬 0

2653.496 - 2677.531 Lex Fridman

Yeah, Schrodinger wrote that living matter, while not alluding to laws of physics as established up to date, is likely to involve other laws of physics hitherto unknown. So to him... I love that quote. There was a sense that at the bottom of this are new laws of physics that could explain this thing that we call life.

0
💬 0

2678.372 - 2706.183 Sarah Walker

Yeah, Schrodinger really tried to... to do what physicists try to do, which is explain things. And his attempt was to try to explain life in terms of non-equilibrium physics, because he thought that was the best description that we could generate at the time. And so he did come up with something really insightful, which was to predict the structure of DNA as an aperiodic crystal.

0
💬 0

2707.207 - 2726.343 Sarah Walker

And that was for a very precise reason that, you know, that was the only kind of physical structure that could encode enough information to actually specify a cell. We knew some things about genes but not about DNA and its actual structure. when he proposed that. But in the book, he tried to explain life as kind of going against entropy.

0
💬 0

2726.744 - 2748.06 Sarah Walker

And so some people talked about it as like Schrodinger's paradox, how can life persist when the second law of thermodynamics is there? But in open systems, that's not so problematic. And really the question is, why can life generate so much order? And we don't have a physics to describe that. And it's interesting, you know, generations of physicists have thought about this problem.

0
💬 0

2748.18 - 2765.03 Sarah Walker

Oftentimes it's like when people are retiring, they're like, oh, now I can work on life. Or they're like more senior in their career and they worked on other more traditional problems. And there's still a lot of impetus in the physics community to think that non-equilibrium physics will explain life. But I think that's not the right approach.

0
💬 0

2766.111 - 2774.613 Sarah Walker

I don't think ultimately the solution to what life is, is there. And I don't really... think entropy has much to do with it unless it's entirely reformulated.

0
💬 0

2774.633 - 2780.176 Lex Fridman

Well, because you have to explain how interesting or how complex it emerges from the soup.

0
💬 0

2780.757 - 2782.238 Sarah Walker

Yes. From randomness.

0
💬 0

2782.478 - 2784.639 Lex Fridman

From randomness. Physics currently can't do that.

0
💬 0

2785.04 - 2823.317 Sarah Walker

No. Physics hardly even acknowledges that the universe is random at its base. Yeah, absolutely. you know, he, he formulated laws that had initial conditions and, um, fixed dynamical laws. And that's been sort of become the standard canon of how people think the universe works and how we need to describe any physical system is with an initial condition and a law of motion.

0
💬 0

2824.158 - 2842.865 Sarah Walker

And I think that's not actually the way the universe really works. I think it's a good approximation for the kind of systems that physicists have studied so far. And I think it will radically fail, um, in the long term at describing reality at its more basal levels. I'm not saying there's a base.

0
💬 0

2842.885 - 2855.194 Sarah Walker

I don't think that reality has a ground, and I don't think there's a theory of everything, but I think there are better theories, and I think there are more explanatory theories, and I think we can get to something that explains much more than the current laws of physics do.

0
💬 0

2855.214 - 2858.357 Lex Fridman

When you say theory of everything, you mean like everything, everything?

0
💬 0

2858.897 - 2872.367 Sarah Walker

Yeah, you know, like in physics right now, it's really popular to talk about theories of everything. So string theory is supposed to be a theory of everything because it unifies quantum mechanics and gravity. And, you know, people have their different pet theories of everything.

0
💬 0

2872.427 - 2880.954 Sarah Walker

And the challenge with a theory of everything, I really love this quote from David Krakauer, which is a theory of everything is a theory of everything except those things that theorize.

0
💬 0

2881.334 - 2883.675 Lex Fridman

Oh, you mean removing the observer from the thing.

0
💬 0

2883.855 - 2897.401 Sarah Walker

Yeah, but it's also weird because if a theory of everything explained everything, it should also explain the theory. So the theory has to be recursive. And none of our theories of physics are recursive. So it's a weird concept.

0
💬 0

2897.721 - 2900.602 Lex Fridman

Yeah, but it's very difficult to integrate the observer into a theory.

0
💬 0

2900.622 - 2905.724 Sarah Walker

I don't think so. I think you can build a theory acknowledging that you're an observer inside the universe.

0
💬 0

2906.308 - 2912.974 Lex Fridman

But doesn't it become recursive in that way? And that's, you're saying it's possible to make a theory that's okay with that?

0
💬 0

2913.654 - 2932.911 Sarah Walker

I think so. I mean, I don't think, there's always going to be the paradox of another meta level you could build on the meta level, right? So like if you assume this is your universe and you're the observer outside of it, you have some meta description of that universe, but then you need a meta description of you describing that universe, right? So, you know, this is one of,

0
💬 0

2933.672 - 2951.273 Sarah Walker

The biggest challenges that we face being observers inside our universe and also, you know, why the paradoxes and the foundations of mathematics and any place that we try to have observers in the system or a system describing itself show up. But I think it is possible to build a physics system.

0
💬 0

2951.753 - 2976.817 Sarah Walker

that builds in those things intrinsically without having them be paradoxical or have holes in the descriptions. And so one place I think about this quite a lot, which I think can give you sort of a more concrete example, is the nature of what we call fundamental. So we typically define fundamental right now in terms of the smallest indivisible units of matter.

0
💬 0

2976.917 - 2987.46 Sarah Walker

So again, you have to have a definition of what you think material is and matter is. But right now, what's fundamental are elementary particles. And we think they're fundamental because we can't break them apart further.

0
💬 0

2987.58 - 3001.004 Sarah Walker

And obviously we have theories like string theory that if they're right, would replace the current description of what's the most fundamental thing in our universe by replacing it with something smaller. But we can't get to those theories because we're technologically limited.

0
💬 0

3001.804 - 3023.947 Sarah Walker

And so if you look at this from a historical perspective and you think about explanations changing as physical systems like us learn more about the reality in which they live, we once considered atoms to be the most fundamental thing. And, you know, it literally comes from the word indivisible.

0
💬 0

3024.067 - 3039.545 Sarah Walker

And then we realized atoms had substructure because we built better technology, which allowed us to quote unquote, see the world better and resolve smaller features of it. And then we built even better technology, which allowed us to see even smaller structure and get down to the standard model. particles.

0
💬 0

3039.705 - 3063.462 Sarah Walker

And we think that there might be structure below that, but we can't get there yet with our technology. So what's fundamental, the way we talk about it in current physics is not actually fundamental. It's the boundaries of what we can observe in our universe, what we can see with our technology. And so if you want to build a theory that's about us and about what

0
💬 0

3064.73 - 3079.139 Sarah Walker

What's inside the universe that we can observe, not what's at the boundary of it. You need to talk about objects that are in the universe that you can actually break apart to smaller things. So I think the things that are fundamental are actually the constructed objects.

0
💬 0

3079.199 - 3093.735 Sarah Walker

They're the ones that really exist and you really understand their properties because you know how the universe constructed them because you can actually take them apart. You can understand the intrinsic laws that built them. But the things at the boundary are just at the boundary. They're evolving with us, and we'll learn more about that structure as we go along.

0
💬 0

3094.316 - 3110.446 Sarah Walker

But really, if we want to talk about what's fundamental inside our universe, we have to talk about all these things that are traditionally considered emergent, but really just structures in time that have causal histories that constructed them and are really actually what our universe is about.

0
💬 0

3111.069 - 3120.937 Lex Fridman

So we should focus on the construction methodology as the fundamental thing. Do you think there's a bottom to the smallest possible thing that makes up the universe?

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3121.157 - 3122.058 Sarah Walker

I don't see one.

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3122.959 - 3129.004 Lex Fridman

And it'll take way too long. It'll take longer to find that than it will to understand the mechanism that created life.

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3129.605 - 3147.851 Sarah Walker

I think so, yeah. I think for me, the frontier in modern physics, where the new physics lies is not in high energy particle physics. It's not in quantum gravity. It's not in any of these sort of traditionally sold, this is going to be the newest, deepest insight we have into the nature of reality. It is going to be in studying the problems of life.

0
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3148.411 - 3162.644 Sarah Walker

and intelligence and the things that are sort of also our current existential crises as a civilization or a culture that's going through an existential trauma of inventing technologies that we don't understand right now.

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3163.105 - 3173.674 Lex Fridman

The existential trauma and the terror we feel that that technology might somehow destroy us, us meaning living, intelligent living organisms, yet we don't understand what that even means.

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3174.375 - 3182.838 Sarah Walker

Well, humans have always been afraid of our technologies though, right? So it's kind of a fascinating thing that every time we invent something we don't understand, it takes us a little while to catch up with it.

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3182.918 - 3186.179 Lex Fridman

I think also in part humans kind of love being afraid.

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3186.619 - 3187.779 Sarah Walker

Yeah, we love being traumatized.

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3188.139 - 3188.599 Lex Fridman

It's weird.

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3189.58 - 3209.371 Sarah Walker

We want to learn more. And then when we learn more, it traumatizes us. You know, I never thought about it this before, but I think this is one of the reasons I love what I do is because it traumatizes me all the time. That sounds really bad. But what I mean is like, I love the shock of like realizing that like coming to understand something in a way that you never understood it before.

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3209.391 - 3221.943 Sarah Walker

I think it seems to me when I see a lot of the ways other people react to new ideas that they don't feel that way intrinsically. But for me, that's like, that's why I do what I do. I love that feeling.

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3222.183 - 3235.786 Lex Fridman

But you're also working on... a topic where it's fundamentally ego destroying because you're talking about like life. It's humbling to think that we're not the individual human is not special.

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3236.667 - 3237.108 Sarah Walker

Yeah.

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3237.308 - 3240.172 Lex Fridman

And you're like very viscerally exploring that.

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3240.774 - 3259.743 Sarah Walker

Yeah, I'm trying to embody that because I think you have to live the physics to understand it. But there's a great quote about Einstein. I don't know if this is true or not, that he once said that he could feel a light beam in his belly. And I think – but I think like you got to think about it though, right?

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3259.763 - 3267.627 Sarah Walker

Like if you're a really deep thinker and you're really thinking about reality that deeply and you are part of the reality that you're trying to describe, like you feel it. You really feel it.

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3267.987 - 3274.731 Lex Fridman

That's what I was saying about you're always walking along the cliff. If you fall off, you're falling into madness.

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3275.072 - 3278.614 Sarah Walker

Yes. It's a constant, constant descent into madness.

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3278.654 - 3283.717 Lex Fridman

The fascinating thing about physicists and madness is that you don't know if you've fallen off the cliff.

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3283.877 - 3284.698 Sarah Walker

Yeah, you know you don't know.

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3284.898 - 3286.179 Lex Fridman

That's the cool thing about madness.

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3286.199 - 3292.843 Sarah Walker

I rely on other people to tell me. Actually, this is very funny because I have these conversations with my students often. They're worried about going crazy.

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3296.027 - 3300.269 Lee Cronin

Reassure them that one of the reasons they'll stay sane is by trying to work on concrete problems.

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3302.01 - 3313.235 Lex Fridman

Going crazy or waking up. I don't know which one it is. Yeah. So what do you think is the origin of life on Earth? And how can we talk about it in a productive way?

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3313.855 - 3339.307 Sarah Walker

The origin of life is like this boundary that the universe can only cross if If a structure that emerges can reinforce its own existence, which is self-reproduction, autocatalysis, things people traditionally talk about, but it has to be able to maintain its own existence against this sort of randomness that happens in chemistry and this randomness that happens in the quantum world.

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3339.967 - 3353.353 Sarah Walker

And like it's in some sense the emergence of like a deterministic structure that says, you know, I'm going to exist and I'm going to keep going. But, you know, pinning that down is really hard. We have ways of thinking about it in assembly theory that I think are pretty rigorous.

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3353.413 - 3378.126 Sarah Walker

And one of the things I'm really excited about is trying to actually quantify in an assembly theoretic way when the original life happens. But the basic process I have in mind is, is a system that has no causal contingency, no constraints of objects basically constraining the existence of other objects or allowing the existence of other objects.

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3379.126 - 3402.589 Sarah Walker

And so that sounds very abstract, but you can just think of a chemical reaction can't happen if there's not a catalyst, for example, or a baby can't be born if there wasn't a parent. So there's a lot of causal contingency that's necessary for certain things to happen. So- You think about this sort of unconstrained, random system. There's nothing that reinforces the existence of other things.

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3402.849 - 3422.099 Sarah Walker

So the sort of resources just get washed out in all of these different structures, and none of them exist again. Or they just, you know, they're not very complicated if they're in high abundance. And some random events allow some things to start reinforcing the existence of a small subset of objects.

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3422.399 - 3435.629 Sarah Walker

And if they can do that, you know, like just molecules basically recognizing each other and being able to catalyze certain reactions, there's this kind of transition point that happens where,

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3436.229 - 3456.423 Sarah Walker

where unless you get a self-reinforcing structure, something that can maintain its own existence, it actually can't cross this boundary to make any objects in high abundance without having this sort of past history that it's carrying with us and maintaining the existence of that past history.

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3456.823 - 3480.244 Sarah Walker

And that boundary point where objects can't exist unless they have the selection and history in them is what we call the original life. And pretty much everything beyond that boundary is holding on for dear life to all of the causation and causal structure that's basically put it there. And it's carving its way through this possibility space into generating more and more structure.

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3480.364 - 3495.969 Sarah Walker

And that's when you get the open-ended cascade of evolution. But that boundary point is really hard to cross. And then what happens when you cross that boundary point and the way objects come into existence is also like really fascinating dynamics because, you know, like as things become more complex, the assembly index increases. I can explain all these things.

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3496.009 - 3508.535 Sarah Walker

Sorry, you can tell me what you want to explain. I mean, explain what people will want to hear. Sorry, I have like a very vivid visual in my brain and it's really hard to articulate it.

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3508.595 - 3509.736 Lex Fridman

Got to convert it to language.

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3510.056 - 3517.459 Sarah Walker

I know. It's so hard. It's going from like a feeling to a visual to language is so stifling sometimes.

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3517.479 - 3522.021 Lex Fridman

I have to convert it from language to a visual, to a feeling.

0
💬 0

3522.802 - 3523.122 Sarah Walker

Yeah.

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💬 0

3523.142 - 3524.022 Lex Fridman

I think it's working.

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💬 0

3524.723 - 3525.223 Sarah Walker

I hope so.

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3526.092 - 3536.752 Lex Fridman

I really like the self-reinforcing objects. I mean, just so I understand, one way to create a lot of the same kind of object is make them self-reinforcing.

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3537.975 - 3560.437 Sarah Walker

Yes. So self-reproduction has this property, right? Like if the system can make itself, then it can persist in time, right? Because all objects decay. They all have a finite lifetime. So if you're able to make a copy of yourself before you die, before the second law eats you or whatever people think happens, then that structure can persist in time.

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3560.854 - 3565.896 Lex Fridman

So that's a way to sort of emerge out of a random soup, out of the randomness of soup.

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