Sara Walker: The Origin of Life on Earth and Alien Worlds
生物与进化物理与宇宙学音乐与艺术哲学与宗教太空与探索
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AI 智能总结
萨拉·沃克谈地球生命起源与外星世界
这是 Lex Fridman 与亚利桑那州立大学天体生物学家 Sara Walker 的深度对话。Walker 探讨了生命的起源、生命的普遍定义、如何在其他星球上寻找生命，以及信息在生命中的核心作用。
生命起源天体生物学组装理论外星生命信息论生命定义
Sara Walker 是亚利桑那州立大学天体生物学和理论物理学教授，圣塔菲研究所研究员，专注于生命起源、生命的普遍定义和外星生命探索，是「组装理论」的提出者之一。
📌 核心观点
- 生命的信息理论：Walker 认为生命的本质是信息——不是物质或能量，而是信息的组织方式。她提出「组装理论」（Assembly Theory），用来量化一个物体需要多少历史信息才能存在，这可以作为生命的普遍标志。
- 生命的起源：Walker 认为生命的起源是宇宙中最深刻的谜题之一，它不仅仅是化学问题，更是信息问题——生命如何从无序的化学物质中涌现出有序的信息处理系统？
- 寻找外星生命：Walker 认为我们需要重新思考如何寻找外星生命，不应该只寻找与地球生命相似的形式，而应该寻找信息复杂性的普遍标志。她认为外星生命可能与我们完全不同。
- 时间与生命：Walker 认为生命的独特之处在于它能够「记住」过去并「预测」未来，这种时间性是生命与非生命物质的根本区别。
- 物理学与生物学的统一：Walker 致力于建立一个统一的生命理论，将物理学、化学、信息论和生物学整合在一起，这是科学中最雄心勃勃的目标之一。
✨ 金句摘录
Walker：生命的本质是信息——不是物质或能量，而是信息的组织方式。
Walker：我们需要重新思考如何寻找外星生命——不应该只寻找与地球生命相似的形式。
Walker：生命的独特之处在于它能够「记住」过去并「预测」未来——这种时间性是生命与非生命物质的根本区别。
📋 章节目录
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🔑 关键词
donphysicsuniverseearthexistconsciousnesshistoryexistencepossibleoriginphysicaltalkinterestinglookingdoesnlawsrnaspacefundamentalguess
💬 精彩语录
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🎙️ 完整对话（2960 条）
Lex Fridman (00:00.000)
The following is a conversation with Sarah Walker,
Lex Fridman (00:02.400)
an astrobiologist and theoretical physicist
Lex Fridman (00:05.000)
at Arizona State University and the Santa Fe Institute.
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She's interested in the origin of life,
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how to find life on other worlds,
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and in general, the more fundamental question
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of what even life is.
Sara Walker (00:18.160)
She seeks to discover the universal laws
Lex Fridman (00:20.260)
that describe living systems on Earth and elsewhere
Sara Walker (00:23.400)
using physics, biology, and computation.
Lex Fridman (00:26.440)
Quick mention of our sponsors, Athletic Greens,
Sara Walker (00:30.360)
NetSuite, Blinkist, and Magic Spoon.
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Check them out in the description to support this podcast.
Sara Walker (00:36.280)
As a side note, let me say that my hope for this podcast
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is to try and alternate between technical
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and nontechnical discussions,
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to jump from the big picture
Sara Walker (00:45.720)
down to specific detailed research
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and back to the big picture,
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and to do so with scientists and non scientists.
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Long term, I hope to alternate between discussions
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of cutting edge research in AI, physics, biology,
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to topics of music, sport, and history,
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and then back to AI.
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AI is home.
Sara Walker (01:06.700)
I hope you come along with me
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for that wild, oscillating journey.
Sara Walker (01:11.520)
Some people message me saying to slow down
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since they're falling behind
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on the episodes of this podcast.
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To their disappointment, I have to say
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that I'll probably do more episodes, not less,
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but you really don't need to listen to every episode.
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Just listen to the ones that spark your curiosity.
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Think about it like a party full of strangers.
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You don't have to talk to everyone.
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Just walk over to the ones who look interesting
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and get to know them.
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And if you're lucky, that one conversation with a stranger
Sara Walker (01:39.400)
might change the direction of your life.
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And it's a short life, so be picky with the strangers
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you talk to at this metaphorical party.
Lex Fridman (01:47.560)
This is the Lex Friedman podcast,
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and here is my conversation with Sarah Walker.
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How did life originate on Earth?
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What are the various hypotheses
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for how life originated on Earth?
Sara Walker (02:00.000)
Yeah, so I guess you're asking a historical question,
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which is always a good place to start thinking about life.
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So there's a lot of ideas about how life started on Earth.
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Probably the most popular
Sara Walker (02:11.840)
is what's called the RNA world scenario.
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So this idea is probably the one
Sara Walker (02:17.920)
that you'll see most reported in the news.
Lex Fridman (02:20.020)
And is based on the idea that there are molecules
Sara Walker (02:27.260)
in our bodies that relay genetic information.
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And we know those as DNA, obviously,
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but there's also a sort of an intermediary called RNA,
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ribonucleic acid, that also plays the role of proteins.
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And people came up with this idea in the 80s
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that maybe that was the first genetic material
Sara Walker (02:47.180)
because it could play both roles of being genetic
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and performing catalysis.
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And then somehow that idea got reduced to this idea
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that there was a molecule that emerged on early Earth
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and underwent Darwinian evolution,
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and that was the start of life.
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So there's a lot of assumptions packed in there
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that we could unpack,
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but that's sort of the leading hypothesis.
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There's also other ideas about life starting as metabolism.
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And so that's more connected
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to the geochemistry of early Earth.
Lex Fridman (03:17.380)
And it would be kind of more focused on this idea
Lex Fridman (03:19.560)
that you get some kind of catalytic cycle of molecules
Sara Walker (03:22.720)
that can reproduce themselves
Lex Fridman (03:24.060)
and form some kind of metabolism.
Lex Fridman (03:25.860)
And then life starts basically a self organization.
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And then you have to explain how evolution comes later.
Sara Walker (03:31.280)
Right, so that's the difference
Lex Fridman (03:32.700)
between sort of energy and genetic code.
Lex Fridman (03:35.700)
So like energy and information
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are those are the two kind of things there?
Sara Walker (03:39.620)
Yeah, I think that's a good way of putting it.
Lex Fridman (03:41.140)
It's kind of funny,
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because I think most of the people that think about
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these things are really disciplinary bias.
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So the people that tend to think about genetics
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come from a biology background
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and they're really evolution focused.
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And so they're worried about
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where does the information come from?
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And how does it change over time?
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But they're talking about information in a really narrow way
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where they're talking about a genetic sequence.
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And then most of the people that think about metabolism,
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origins of life scenarios tend to be
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people like physicists or geochemists
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that are worried about what are the energy sources
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and what kinds of organization
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can you get out of those energy sources?
Lex Fridman (04:14.100)
Okay, so which one is your favorite?
Lex Fridman (04:15.880)
I don't like either.
Sara Walker (04:17.460)
Okay, all right, can we talk about them
Lex Fridman (04:19.220)
for a little bit longer though?
Sara Walker (04:20.060)
Yeah, no, that's fine.
Lex Fridman (04:23.700)
So okay, so there's early Earth.
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What was that like?
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Was there just mostly covered by oceans?
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Was there heat sources, energy sources?
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So if we talk about the metabolism view
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of the origin of life,
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like where was the source of energy?
Sara Walker (04:38.380)
Probably the most popular view
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for where the origin of life happened on Earth
Sara Walker (04:42.220)
is hydrothermal vents because they had sufficient energy.
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And so we don't really know a lot about early Earth.
Sara Walker (04:50.180)
We have some ideas about when oceans first formed
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and things like that,
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but the time of the origin of life
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is kind of not well understood or pinned down
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and the conditions on Earth at that time are not well known.
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But a lot of people do think
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that there was probably hydrothermal vents
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which are really hot, chemically active regions,
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say on the seafloor in modern times,
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which also would have been present on early Earth.
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And they would have provided energy and organics
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and basically all of the right conditions
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for the origins of life,
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which is one of the reasons
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that we look for these hydrothermal systems
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when we're talking about life elsewhere too.
Sara Walker (05:27.300)
Okay, and for the genetic code,
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the idea is that the RNA is the first,
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like why would RNA be the first moment you can say it's life?
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I guess the idea is it could both
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have persistent information
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and then it can also do some of the work
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of like what, creating a self sustaining organism?
Lex Fridman (05:49.100)
Yeah, that's the basic idea.
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So the idea is you have, in an RNA molecule,
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you have a sequence of characters, say,
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so you can treat it like a string in a computer
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and it can be copied.
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So information can be propagated,
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which is important for evolution
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because evolution happens
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by having inheritance of information.
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So for example, like my eyes are brown
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because my mother's eyes were brown.
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So you need that copying of information,
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but then you also have the ability to perform catalysis,
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which means that that RNA molecule
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is not inert in that environment,
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but it actually interacts with something
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and could potentially mediate, say, a metabolism
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that could then fuel the actual reproduction
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of that molecule.
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So in some ways, people think that RNA gives you
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the most bang for your buck in a single molecule
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and therefore, it gives you all the features
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that you might think are life.
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And so this is sort of where this RNA world conjecture
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came from is because of those two properties.
Lex Fridman (06:54.540)
Isn't it amazing that RNA came to be in general?
Lex Fridman (06:59.100)
Isn't it? Yes, that is amazing.
Sara Walker (07:01.100)
Okay, so we're not talking down about RNA.
Lex Fridman (07:03.660)
No, no, I love RNA.
Sara Walker (07:04.820)
It's one of my favorite molecules.
Lex Fridman (07:06.180)
I think it's beautiful. It's just not step one.
Sara Walker (07:08.700)
Yeah, I think the issue,
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it's not even the RNA world is a problem
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and actually, if you really dig into it,
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the RNA world is not one hypothesis.
Sara Walker (07:19.340)
It is a set of hypothesis, hypotheses, sorry.
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And they range from a molecule of RNA spontaneously emerged
Sara Walker (07:27.380)
on the early Earth and started evolving,
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which is kind of like the hardest RNA world scenario,
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which is the one I cited and I get a little animated about
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because it seems so blatantly wrong to me,
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but that's a separate story.
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And then the other one is actually something I agree with,
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which is that you can say there was an RNA world
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because RNA was the first genetic material
Sara Walker (07:49.180)
for life on Earth.
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So an RNA world could just be the earliest organisms
Sara Walker (07:54.700)
that had genetics in a modern sense,
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didn't have DNA evolved yet, they had RNA, right?
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And so that's sort of a softer RNA world scenario
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in the sense that it doesn't mean it was the first thing
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that happened, but it was a thing that definitely was part
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of the lineage of events that led to us.
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So if a life was like a best of album,
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it would be on the, it'd be one of the songs on there.
Sara Walker (08:18.820)
Yes. One of the early songs.
Lex Fridman (08:19.860)
Okay.
Sara Walker (08:20.700)
It's on the greatest hits.
Lex Fridman (08:21.660)
Greatest hits, that's the word I was looking for.
Sara Walker (08:23.740)
Okay.
Lex Fridman (08:24.580)
Did life, do you think, originate once, twice,
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three times on Earth, multiple times?
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What do you think?
Sara Walker (08:31.780)
I think that's a really difficult question.
Lex Fridman (08:33.860)
Is it an important question?
Sara Walker (08:35.460)
It's a super important question.
Lex Fridman (08:36.700)
No, it's a really important question.
Lex Fridman (08:39.500)
And so there's a lot of questions in that question.
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So one of the first ones that I think needs to be addressed
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is is the origin of life a continuous process
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on our planet?
Lex Fridman (08:52.020)
So we think about the origin of life as something
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that happened on Earth, say almost 4 billion years ago,
Sara Walker (08:58.180)
because we have evidence of life emerging very early
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on our planet.
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And then an origin of life event, quote unquote,
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a singular event, whatever that was, happened.
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And then all life on Earth that we know is a descendant
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of that particular event in our universe, right?
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And so, but we don't have any idea one way or the other
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if the origin of life is happening repeatedly,
Lex Fridman (09:25.020)
and maybe it's just not taking off
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because life is already established.
Sara Walker (09:27.660)
That's a argument that people will make,
Lex Fridman (09:29.540)
or maybe there are alternative forms of life on Earth
Sara Walker (09:33.140)
that we don't even recognize.
Lex Fridman (09:35.340)
So this is the idea of a shadow biosphere
Sara Walker (09:36.860)
that there actually might just be
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completely other life on Earth,
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but it's so alien that we don't even know what it is.
Lex Fridman (09:42.940)
I'm gonna have to talk to you about the shadow biosphere.
Sara Walker (09:45.380)
Yeah, that's a fun one.
Lex Fridman (09:46.420)
In a second, but first, let me ask for the other alternative,
Sara Walker (09:49.740)
which is panspermia.
Lex Fridman (09:51.400)
Right.
Lex Fridman (09:52.240)
So that's the idea, the hypothesis that life exists
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elsewhere in the universe and got to us
Sara Walker (09:57.300)
through like an asteroid or a planetoid
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or some, according to Wikipedia, space dust,
Sara Walker (10:02.660)
whatever the heck that is.
Lex Fridman (10:05.380)
It sounds fun.
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But basically, it rode along whatever kind of rock
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and got to us.
Lex Fridman (10:11.820)
Do you think that's at all a possibility?
Lex Fridman (10:15.020)
Sure.
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So I think the reason that most original life scientists
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are interested in the original life on Earth
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and say not the original life on Mars
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and then panspermia,
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the exchange of life between planets being the explanation
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is once you start removing the original life from Earth,
Sara Walker (10:32.020)
you know even less about it
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than you do if you study it on Earth.
Sara Walker (10:36.060)
Although, I think there are ways
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of reformulating the problem.
Sara Walker (10:38.780)
This is why I said earlier,
Lex Fridman (10:40.460)
oh, you mean the historical original life problem.
Sara Walker (10:42.460)
You don't mean the problem of how does life arise
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in the universe and what the universal principles are
Sara Walker (10:47.340)
because there's this historic problem,
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how did it happen on early Earth?
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And there's a more tractable general problem
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of how does it happen?
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And how does it happen is something we can actually ask
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in the lab.
Lex Fridman (10:58.100)
How did it happen on early Earth
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is a much more detailed and nuanced question
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and requires detailed knowledge of what was happening
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on early Earth that we don't have.
Lex Fridman (11:08.980)
And I'm personally more interested in general mechanisms.
Lex Fridman (11:11.380)
So to me, it doesn't matter if it happened on Earth
Sara Walker (11:13.180)
or it happened on Mars.
Lex Fridman (11:15.140)
It just matters that it happened.
Sara Walker (11:16.700)
We have evidence it happened.
Lex Fridman (11:18.520)
The question is, did it happen more than once
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in our universe?
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And so the reason I don't find panspermia
Sara Walker (11:24.260)
as a particularly,
Lex Fridman (11:25.940)
I think it's a fascinating hypothesis.
Sara Walker (11:28.740)
I definitely think it's possible.
Lex Fridman (11:30.980)
And I in particular think it's possible
Sara Walker (11:33.820)
once you get to the stage of life where you have technology
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because then you obviously can spread out
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into the cosmos.
Lex Fridman (11:40.220)
But it's also possible for microbes
Sara Walker (11:41.940)
because we know that certain microorganisms
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can survive the journey in space.
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And they can live in a rock and go between Mars and Earth.
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Like people have done experiments
Sara Walker (11:51.940)
to try to prove that could work.
Lex Fridman (11:54.140)
So in that scenario, it's super cool
Sara Walker (11:57.100)
because then you get planetary exchange,
Lex Fridman (11:58.340)
but say we go look for life on Mars
Lex Fridman (12:00.560)
and it ends up being exactly the same life we have on Earth,
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biochemically speaking,
Sara Walker (12:04.340)
then we haven't really discovered something new
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about the universe.
Lex Fridman (12:06.980)
What kind of aliens are possible
Lex Fridman (12:08.620)
were there other origin of life events?
Sara Walker (12:10.780)
If we find, if all the life we ever find
Lex Fridman (12:12.980)
is the same origin of life event in the universe,
Sara Walker (12:14.740)
it doesn't help me solve my problem.
Lex Fridman (12:16.580)
But it's possible that that would be a sign
Sara Walker (12:19.380)
that you could separate the environment
Lex Fridman (12:22.260)
from the basic ingredients.
Sara Walker (12:24.780)
Yes, that's true.
Lex Fridman (12:25.620)
So you can have like a life gun
Sara Walker (12:27.860)
that you shoot throughout the universe.
Lex Fridman (12:30.100)
And then like once you shoot it,
Sara Walker (12:32.900)
it's like the Simpsons with a makeup gun.
Lex Fridman (12:34.900)
That was a great episode.
Sara Walker (12:36.280)
When you shoot this life gun,
Lex Fridman (12:39.060)
it'll find the Earth's, it'll like get sticky.
Sara Walker (12:42.380)
It'll stick to the Earth's.
Lex Fridman (12:44.180)
And that kind of reduces the barrier
Sara Walker (12:46.860)
of like the time it takes,
Lex Fridman (12:49.580)
the luck it takes to actually,
Sara Walker (12:52.220)
from nothing, from the basic chemistry,
Lex Fridman (12:54.660)
from the basic physics of the universe
Sara Walker (12:56.300)
for the life to spring up.
Lex Fridman (12:58.540)
Yeah, I think this is actually super important
Sara Walker (13:00.780)
to just think about,
Lex Fridman (13:01.700)
like does life getting seated on a planet
Lex Fridman (13:05.540)
have to be geochemically compatible with that planet?
Lex Fridman (13:08.820)
So you're suggesting like we could just shoot guns in space
Lex Fridman (13:11.340)
and like life could go to Mars
Lex Fridman (13:13.140)
and then it would just live there and be happy there.
Lex Fridman (13:16.500)
But that's actually an open question.
Lex Fridman (13:18.400)
So one of the things I was gonna say in response
Sara Walker (13:20.040)
to your question about whether the origin of life
Lex Fridman (13:22.620)
happened once or multiple times,
Sara Walker (13:24.420)
is for me personally right now in my thinking,
Lex Fridman (13:26.400)
although this changes on a weekly basis,
Lex Fridman (13:28.400)
but is that I think of life more as a planetary phenomenon.
Lex Fridman (13:31.740)
So I think the origin of life
Sara Walker (13:32.740)
because life is so intimately tied to planetary cycles
Lex Fridman (13:37.380)
and planetary processes,
Lex Fridman (13:38.780)
and this goes all the way back
Lex Fridman (13:39.980)
through the history of our planet,
Sara Walker (13:41.540)
that the origin of life itself grew out of geochemistry
Lex Fridman (13:44.220)
and became coupled and controlled geochemistry.
Lex Fridman (13:46.300)
And when we start to talk about life existing on the planet
Lex Fridman (13:49.160)
is when we have evidence of life
Sara Walker (13:51.220)
actually influencing properties of the planet.
Lex Fridman (13:55.060)
And so if life is a planetary property,
Sara Walker (13:59.220)
then going to Mars is not a trivial thing
Lex Fridman (14:01.660)
because you basically have to make Mars more Earth like.
Lex Fridman (14:05.520)
And so in some sense,
Lex Fridman (14:07.620)
like when I think about sort of longterm vision
Sara Walker (14:09.460)
of humans in space, for example,
Lex Fridman (14:11.700)
really what you're talking about when you're saying,
Sara Walker (14:14.020)
let's send our civilization to Mars
Lex Fridman (14:16.620)
is you're not saying let's send our civilization to Mars,
Sara Walker (14:18.660)
you're saying let's reproduce our planet on Mars.
Lex Fridman (14:21.900)
Like the information from our planet
Sara Walker (14:23.220)
actually has to go to Mars and make Mars more Earth like,
Lex Fridman (14:26.180)
which means that you're now having a reproduction process,
Sara Walker (14:28.560)
like a cell reproduces itself
Lex Fridman (14:29.940)
to propagate information in the future.
Sara Walker (14:32.540)
Planets have to figure out how to reproduce their conditions,
Lex Fridman (14:35.280)
including geochemical conditions on other planets
Sara Walker (14:37.980)
in order to actually reproduce life in the universe,
Lex Fridman (14:40.360)
which is kind of a little bit radical,
Lex Fridman (14:41.700)
but I think for longterm sustainability
Lex Fridman (14:44.380)
of life on a planet, that's absolutely essential.
Sara Walker (14:47.300)
Okay, so if we were to think about life
Lex Fridman (14:50.680)
as a planetary phenomena,
Lex Fridman (14:52.780)
and so life on Mars would be best
Lex Fridman (14:55.100)
if it's way different than life on Earth,
Sara Walker (14:57.580)
we have to ask the very basic question
Lex Fridman (14:59.620)
of what is life?
Sara Walker (15:03.380)
I actually don't think that's the right question to ask.
Lex Fridman (15:06.180)
It took me a long time to get there, right?
Lex Fridman (15:07.740)
So I... Cross it out.
Lex Fridman (15:08.820)
Yeah, cross it off your list, it's wrong.
Sara Walker (15:11.660)
Next question.
Lex Fridman (15:13.020)
No, no, no, I mean, I think it has an answer,
Lex Fridman (15:15.220)
but I think the part of the problem is,
Lex Fridman (15:17.820)
you know, most of the places in science
Sara Walker (15:19.260)
where we get really stuck
Lex Fridman (15:20.100)
is because we don't know what questions to ask.
Lex Fridman (15:22.260)
And so you can't answer a question
Lex Fridman (15:24.020)
if you're asking the wrong question.
Lex Fridman (15:25.860)
And I think the way I think about it
Lex Fridman (15:29.380)
is obviously I'm interested in what life is.
Lex Fridman (15:31.180)
So I'm being a little cheeky when I say
Lex Fridman (15:32.460)
that's the wrong question to ask.
Sara Walker (15:33.580)
That's exactly like the question
Lex Fridman (15:35.420)
that's like the core of my existence.
Lex Fridman (15:36.980)
But I think the way of framing that
Lex Fridman (15:40.780)
is what is it about our universe
Lex Fridman (15:43.140)
that allows features that we associate life to be there?
Lex Fridman (15:47.440)
And so really what I guess when I'm asking that question,
Lex Fridman (15:50.300)
what I'm after is an explanatory framework
Lex Fridman (15:52.620)
for what life is, right?
Lex Fridman (15:54.340)
And so most people, they try to go in and define life
Lex Fridman (15:57.380)
and they say, well, life is say,
Sara Walker (15:59.660)
a self reproducing chemical system
Lex Fridman (16:01.680)
capable of Darwinian evolution.
Sara Walker (16:02.980)
That's a very popular definition for life.
Lex Fridman (16:05.440)
Or life is something that metabolizes and eats.
Sara Walker (16:08.340)
That is not how I think about life.
Lex Fridman (16:10.060)
What I think about life is there are principles
Lex Fridman (16:13.260)
and laws that govern our universe
Lex Fridman (16:15.640)
that we don't understand yet,
Sara Walker (16:17.980)
that have something to do with how information interacts
Lex Fridman (16:22.340)
with the physical world.
Sara Walker (16:23.660)
I don't know exactly what I mean even when I say that,
Lex Fridman (16:26.300)
because we don't know these rules,
Lex Fridman (16:28.460)
but it's a little bit like, I like to use analogies.
Lex Fridman (16:32.180)
You give me time to be like a little long winded
Sara Walker (16:34.480)
for a second, even in as I,
Lex Fridman (16:36.700)
but sort of like if you look at the history of physics,
Sara Walker (16:39.520)
for example, this is like,
Lex Fridman (16:40.740)
so we are in the period of the development of thought
Sara Walker (16:45.220)
on our planet where we don't understand what we are yet.
Lex Fridman (16:47.980)
Right?
Sara Walker (16:49.100)
There was a period of thought in the history of our planet
Lex Fridman (16:51.660)
where we didn't understand what gravity was.
Lex Fridman (16:53.820)
And we didn't understand, for example,
Lex Fridman (16:55.740)
that planets in the heavens were actually planets
Sara Walker (16:59.340)
or that they operated by the same laws that we did.
Lex Fridman (17:02.060)
And so there has been this sort of progression
Sara Walker (17:05.140)
of getting a deeper understanding
Lex Fridman (17:07.460)
of explaining basic phenomena.
Sara Walker (17:09.060)
Like, I'm not gonna drop the cup.
Lex Fridman (17:10.420)
I'll drop the water bottle.
Sara Walker (17:11.260)
There you go.
Lex Fridman (17:12.100)
Okay, that fell, right?
Lex Fridman (17:13.140)
But why did that fall?
Lex Fridman (17:16.300)
This is why I'm a theorist, not an experimentalist.
Sara Walker (17:19.180)
That could have gone wrong in so many ways.
Lex Fridman (17:20.900)
I know, it could have,
Sara Walker (17:21.740)
especially if I did the cup and it smashed.
Lex Fridman (17:23.700)
So if you take this view
Sara Walker (17:28.700)
that there's sort of some missing principles,
Lex Fridman (17:30.460)
I associate them to information.
Lex Fridman (17:33.700)
And what the sort of feeling there is,
Lex Fridman (17:36.400)
there's some missing explanatory framework
Sara Walker (17:39.060)
for how our universe works.
Lex Fridman (17:40.440)
And if we understood that physics,
Sara Walker (17:42.400)
it would explain what we are.
Lex Fridman (17:44.580)
It might also explain a lot of other features
Sara Walker (17:46.240)
we don't associate to life.
Lex Fridman (17:48.620)
And so it's a little like people accept the fact
Sara Walker (17:51.780)
that gravity is a universal phenomena.
Lex Fridman (17:54.340)
But when we wanna study gravity,
Sara Walker (17:55.560)
we study things like large scale,
Lex Fridman (17:58.420)
galactic structures or black holes or planets.
Sara Walker (18:02.740)
If we wanna understand information
Lex Fridman (18:04.380)
and how it operates in the physical world,
Sara Walker (18:05.860)
we study intelligent systems or living systems
Lex Fridman (18:08.380)
because they are the manifestation of that physics.
Lex Fridman (18:10.980)
And the fact that we can't see that clearly yet,
Lex Fridman (18:13.900)
or we don't have that explanatory framework,
Sara Walker (18:15.700)
I think it's just because we haven't been thinking
Lex Fridman (18:17.420)
about the problem deeply enough.
Lex Fridman (18:18.700)
But I feel like if you're explaining something,
Lex Fridman (18:21.500)
you're deriving it from some more fundamental property.
Lex Fridman (18:24.140)
And of course, I have to say I'm wearing my physicist hat.
Lex Fridman (18:28.780)
So I have a huge bias of liking simple,
Sara Walker (18:31.740)
elegant explanations of the universe
Lex Fridman (18:33.860)
that really are compelling.
Lex Fridman (18:37.340)
But I think one of the things that I've sort of
Lex Fridman (18:39.940)
maybe in some ways rejected my training as a physicist
Sara Walker (18:42.540)
is that most of the elegant explanations
Lex Fridman (18:44.580)
that we have so far don't include us in the universe.
Lex Fridman (18:47.220)
And I can't help but think
Lex Fridman (18:48.660)
there's something really special about what we are.
Lex Fridman (18:50.340)
And there have to be some deep principles at play there.
Lex Fridman (18:54.620)
And so that's sort of my perspective on it.
Sara Walker (18:57.420)
Now, when you ask me what life is,
Lex Fridman (18:59.460)
I have some ideas of what I think it is,
Lex Fridman (19:02.060)
but I think that we haven't gotten there yet
Lex Fridman (19:04.820)
because we haven't been able to see that structure.
Lex Fridman (19:07.420)
And just to go back to the gravity example,
Lex Fridman (19:09.340)
it's a little like in ancient times, they didn't know,
Sara Walker (19:12.380)
I was talking about stars and heavens and things.
Lex Fridman (19:14.540)
They didn't know those were governed by the same principles
Sara Walker (19:17.580)
as that darned experiment.
Lex Fridman (19:19.300)
Here's where I was going with it.
Sara Walker (19:20.900)
Once you realize, like Newton did,
Lex Fridman (19:22.860)
that heavenly motions and earthly motions
Sara Walker (19:25.780)
are governed by the same principles
Lex Fridman (19:27.060)
and you unify terrestrial and celestial motion,
Sara Walker (19:29.060)
you get these more powerful ideas.
Lex Fridman (19:31.220)
And I think where life is is somehow unifying
Sara Walker (19:35.180)
these abstract ideas of computation and information
Lex Fridman (19:38.500)
with the physical world, with matter,
Lex Fridman (19:40.700)
and realizing that there's some explanatory framework
Lex Fridman (19:43.700)
that's not physics and it's not computation,
Lex Fridman (19:46.900)
but it's something that's deeper.
Lex Fridman (19:49.580)
So answering the question of what is life
Sara Walker (19:52.100)
requires deeply understanding something about the universe
Lex Fridman (19:55.900)
as information processing, the universe is computation.
Sara Walker (19:58.900)
Sort of.
Lex Fridman (19:59.740)
It's something about, like would,
Lex Fridman (1:00:00.840)
So we're embracing the tangent.
Lex Fridman (1:00:03.320)
So free will, you believe at this current time
Sara Walker (1:00:08.240)
that you have free will.
Lex Fridman (1:00:09.400)
I believe my whole life I have free will.
Lex Fridman (1:00:11.080)
What is illusion?
Lex Fridman (1:00:11.920)
No, just kidding.
Sara Walker (1:00:12.760)
I still believe it.
Lex Fridman (1:00:14.320)
You still believe it.
Lex Fridman (1:00:15.160)
So at the same time you think that
Lex Fridman (1:00:18.880)
in your conception of the universe,
Sara Walker (1:00:20.840)
causality seems to be pretty fundamental.
Lex Fridman (1:00:23.160)
That's right.
Sara Walker (1:00:24.000)
Which kind of wants the universe to be deterministic.
Lex Fridman (1:00:27.360)
So how the heck do you think you have a free will
Lex Fridman (1:00:31.220)
and yet you value causality?
Lex Fridman (1:00:35.120)
Because I depart from the conception of physics
Sara Walker (1:00:39.760)
that you can write down an initial condition
Lex Fridman (1:00:42.760)
and a fixed law of motion and that will describe everything.
Sara Walker (1:00:45.720)
There's no incompatibility
Lex Fridman (1:00:47.160)
if you are willing to reject that assertion.
Lex Fridman (1:00:49.520)
So where's the randomness?
Lex Fridman (1:00:51.160)
Where's the magic that gives birth to the free will?
Lex Fridman (1:00:54.160)
Is it the randomness of the laws of physics?
Lex Fridman (1:00:56.840)
No, in my mind what free will is,
Sara Walker (1:01:00.080)
is the fact that I as a physical system
Lex Fridman (1:01:03.240)
have causal control over certain things.
Sara Walker (1:01:05.360)
I don't have causal control over everything,
Lex Fridman (1:01:06.960)
but I have a certain set of things.
Lex Fridman (1:01:09.040)
And I'm also, as I described,
Lex Fridman (1:01:12.080)
sort of a nexus of a particular set of histories
Sara Walker (1:01:15.320)
that exist in the universe
Lex Fridman (1:01:16.240)
and a particular set of futures that might exist.
Lex Fridman (1:01:18.600)
And those futures that might exist are in part specified
Lex Fridman (1:01:22.360)
by my physical configuration as me.
Lex Fridman (1:01:25.800)
And therefore, it may not be free will
Lex Fridman (1:01:29.500)
in the traditional sense.
Sara Walker (1:01:30.720)
I don't even know what people mean
Lex Fridman (1:01:31.920)
when they're talking about free will, honestly.
Sara Walker (1:01:33.400)
It's like the whole discussion's really muddled.
Lex Fridman (1:01:35.460)
But in the sense that I am a causal agent,
Sara Walker (1:01:38.320)
if you wanna call it that, that exists in the universe,
Lex Fridman (1:01:40.720)
and there are certain things that happen
Sara Walker (1:01:42.160)
because I exist as me, then yes, I have free will.
Lex Fridman (1:01:45.600)
No, but do you, Sarah, have a choice
Lex Fridman (1:01:50.060)
about what's going to happen next?
Lex Fridman (1:01:51.600)
Oh, I see.
Sara Walker (1:01:53.400)
If the universe, could I have,
Lex Fridman (1:01:55.600)
if I run this universe. Yes, I think so.
Sara Walker (1:01:57.400)
You have a choice.
Lex Fridman (1:01:58.600)
Where does the choice come from?
Sara Walker (1:02:00.240)
I think that's related to the physics of consciousness.
Lex Fridman (1:02:02.280)
So one of the things I didn't say about that,
Sara Walker (1:02:03.960)
I don't know, maybe this is me just being hopeful
Lex Fridman (1:02:06.800)
because maybe I just wanna have free will,
Lex Fridman (1:02:08.640)
but I don't think that we can rule out the possibility
Lex Fridman (1:02:10.800)
because I don't think that we understand enough
Sara Walker (1:02:13.020)
about any of these problems.
Lex Fridman (1:02:14.440)
But I think one of the things that's interesting for me
Sara Walker (1:02:16.400)
about the sort of inversion of the question
Lex Fridman (1:02:18.840)
of consciousness that I proposed
Sara Walker (1:02:21.040)
is one of the features that we do
Lex Fridman (1:02:24.920)
is we have imagination, right?
Lex Fridman (1:02:27.000)
And people don't think about imagination
Lex Fridman (1:02:28.520)
as a physical thing, but it is a physical thing.
Lex Fridman (1:02:30.760)
It exists in the universe, right?
Lex Fridman (1:02:32.480)
And so I'm like really intrigued by the fact that say,
Sara Walker (1:02:35.560)
humans for, another physical system could do this too,
Lex Fridman (1:02:38.720)
it's not special to humans,
Lex Fridman (1:02:39.760)
but for centuries imagined flying machines and rockets,
Lex Fridman (1:02:44.220)
and then we finally built them, right?
Lex Fridman (1:02:45.760)
So they were represented in our minds
Lex Fridman (1:02:47.640)
and on the pages of things that we drew
Sara Walker (1:02:50.040)
for hundreds of years before we could build
Lex Fridman (1:02:51.840)
those physical objects in the universe.
Lex Fridman (1:02:54.040)
But certainly the existence of rockets
Lex Fridman (1:02:56.480)
is in part causally,
Sara Walker (1:03:01.120)
caused by the fact that we could imagine them.
Lex Fridman (1:03:03.640)
And so there seems to be this property
Sara Walker (1:03:07.920)
that some things don't exist,
Lex Fridman (1:03:09.880)
they've never physically existed in the universe,
Lex Fridman (1:03:12.080)
but we can imagine the possibility of them existing
Lex Fridman (1:03:14.680)
and then cause them to exist,
Sara Walker (1:03:16.520)
maybe individually or collectively.
Lex Fridman (1:03:18.480)
And I think that property is related
Sara Walker (1:03:21.000)
to what I would say about having choice or free will,
Lex Fridman (1:03:23.180)
because that set of possibilities,
Sara Walker (1:03:25.440)
those set of things that you can imagine
Lex Fridman (1:03:27.360)
is not constrained to your local physical environment
Lex Fridman (1:03:29.720)
and history.
Lex Fridman (1:03:30.560)
And this is what's a little bit different
Sara Walker (1:03:32.000)
about intelligence as we see it in humans
Lex Fridman (1:03:34.440)
and AI that we wanna build than biological intelligence,
Sara Walker (1:03:37.820)
because biological intelligence is predicated completely
Lex Fridman (1:03:40.680)
on the history of things that's seen in the past,
Lex Fridman (1:03:42.500)
but something happened with the neural architectures
Lex Fridman (1:03:45.400)
that evolved in multicellular organisms
Sara Walker (1:03:48.000)
that they don't just have access to the past history
Lex Fridman (1:03:50.400)
of their particular set of events,
Lex Fridman (1:03:52.400)
but they can imagine things that haven't happened,
Lex Fridman (1:03:55.120)
aren't on their timeline,
Lex Fridman (1:03:56.180)
and as long as they're consistent with the laws of physics,
Lex Fridman (1:03:58.080)
make them happen.
Lex Fridman (1:03:59.560)
So this is fascinating.
Lex Fridman (1:04:02.360)
It's trippy physics, but it exists, so there you go.
Sara Walker (1:04:05.400)
I mean, in some sense,
Lex Fridman (1:04:06.400)
if you look at like general relativity and gravity
Sara Walker (1:04:10.040)
morphing space time in that same way,
Lex Fridman (1:04:12.800)
maybe whatever the physics of consciousness might be,
Sara Walker (1:04:16.200)
it might be morphing, that's like what free will is.
Lex Fridman (1:04:18.760)
It's morphing like the space,
Sara Walker (1:04:21.600)
just like ideas make rockets come to life.
Lex Fridman (1:04:25.000)
It's somehow changing the space of possible realizations
Sara Walker (1:04:30.680)
of like whatever's, yeah, okay, but that's.
Lex Fridman (1:04:33.520)
Life is kind of basically, if you wanna think about it,
Sara Walker (1:04:35.560)
like life is sort of changing the probability distributions
Lex Fridman (1:04:38.480)
over what can exist.
Sara Walker (1:04:39.320)
That's the physics of what life is.
Lex Fridman (1:04:40.960)
And then consciousness is this sort of layered property
Sara Walker (1:04:43.440)
or imagination on top of it
Lex Fridman (1:04:45.160)
that kind of scrambles that a little bit more
Lex Fridman (1:04:47.240)
and like has access to, I don't know.
Lex Fridman (1:04:50.320)
It's kind of, we don't know how to describe it, right?
Sara Walker (1:04:53.040)
Like that's why it's interesting, but.
Lex Fridman (1:04:54.200)
But it's probabilistic.
Lex Fridman (1:04:55.320)
So you do think like God plays dice.
Lex Fridman (1:04:57.440)
So let me.
Sara Walker (1:04:58.560)
No, I think the description is probabilistic.
Lex Fridman (1:05:00.520)
I don't necessarily think
Sara Walker (1:05:02.320)
the underlying physics is probabilistic.
Lex Fridman (1:05:06.280)
I think the way that we can describe this physics
Sara Walker (1:05:09.520)
is going to be probabilistic and statistical,
Lex Fridman (1:05:12.240)
but the under, like when we take measurements in the lab,
Lex Fridman (1:05:14.720)
but the underlying physics itself
Lex Fridman (1:05:15.960)
might still be deterministic.
Sara Walker (1:05:17.080)
I don't know.
Lex Fridman (1:05:18.440)
Maybe I'm, it's hard to know what concepts to hold on to.
Lex Fridman (1:05:22.320)
So I find myself constantly rejecting concepts,
Lex Fridman (1:05:24.760)
but then I have to grab another one
Lex Fridman (1:05:26.160)
and try to hold onto something from intellectual history.
Lex Fridman (1:05:29.640)
Well, it's possible that our mind
Sara Walker (1:05:30.800)
is not able to hold the correct concepts in mind at all.
Lex Fridman (1:05:33.360)
Like we're not able to even conceive of them correctly.
Sara Walker (1:05:36.080)
Maybe the word's deterministic or random
Lex Fridman (1:05:39.000)
or not the right even words, concepts to be holding.
Lex Fridman (1:05:42.360)
But maybe you can talk to the theory of everything,
Lex Fridman (1:05:46.600)
this attempt in the current set of physical laws
Sara Walker (1:05:49.320)
to try to unify them.
Lex Fridman (1:05:50.880)
Is there any hope that once a theory of everything
Sara Walker (1:05:55.280)
is developed, and by theory of everything,
Lex Fridman (1:05:56.840)
I mean in a narrow sense of unifying quantum field theory
Lex Fridman (1:06:00.280)
and general relativity,
Lex Fridman (1:06:01.520)
do you think that will contain some,
Sara Walker (1:06:05.960)
like in order to do that unification,
Lex Fridman (1:06:08.440)
you would have to get something
Sara Walker (1:06:10.760)
that would then give hints about the physics of life,
Lex Fridman (1:06:13.280)
physics of existence, physics of consciousness.
Sara Walker (1:06:15.880)
Yeah, I used to not, but I actually,
Lex Fridman (1:06:18.800)
I have become increasingly convinced that it probably will.
Lex Fridman (1:06:23.880)
And part of the reason is,
Lex Fridman (1:06:25.960)
I think I've talked a little bit already
Sara Walker (1:06:27.600)
about these holes in physics,
Lex Fridman (1:06:29.280)
like the theories we have in physics,
Sara Walker (1:06:32.840)
they have problems, they have lots of problems
Lex Fridman (1:06:35.360)
and they're very deep problems
Lex Fridman (1:06:37.120)
and we don't know how to patch them.
Lex Fridman (1:06:39.040)
And some of those problems become very evident
Sara Walker (1:06:41.200)
when you try to patch quantum mechanics
Lex Fridman (1:06:43.440)
and general relativity together.
Lex Fridman (1:06:45.680)
So there is this kind of interesting feature
Lex Fridman (1:06:47.520)
that some of the ways of patching that
Sara Walker (1:06:49.840)
might actually closely resemble the physics of life.
Lex Fridman (1:06:54.200)
And so the place where that actually comes up most,
Lex Fridman (1:06:56.440)
and actually we just had a workshop
Lex Fridman (1:06:58.120)
in the Beyond Center where I work
Sara Walker (1:06:59.040)
at Arizona State University,
Lex Fridman (1:07:00.600)
and Lee Smolin made this point that he thinks
Sara Walker (1:07:02.760)
that the theory of quantum gravity when we solve it
Lex Fridman (1:07:05.080)
is gonna be the same theory that gives rise to life.
Lex Fridman (1:07:08.440)
And I think that I agree with him on some levels
Lex Fridman (1:07:11.440)
because there's something very interesting where,
Sara Walker (1:07:13.720)
if you look at these sort of causal set theories of gravity
Lex Fridman (1:07:17.280)
where they're looking for space as being emergent.
Lex Fridman (1:07:21.840)
And so space time is an emergent concept from a causal set,
Lex Fridman (1:07:24.640)
which is also sort of related, I think,
Sara Walker (1:07:26.440)
to what Wolfram's doing with his physics project.
Lex Fridman (1:07:29.200)
It's the same kind of underlying math
Sara Walker (1:07:30.800)
that we have in this theory that we've been developing
Lex Fridman (1:07:32.920)
related to life called assembly theory,
Sara Walker (1:07:35.200)
which is basically trying to look at complex objects
Lex Fridman (1:07:39.800)
like molecules and bacteria and living things
Sara Walker (1:07:44.160)
as basically being assembled from a set of component parts
Lex Fridman (1:07:52.280)
and that they actually encode all the possible histories
Sara Walker (1:07:54.640)
that they could have in that physical object.
Lex Fridman (1:07:56.640)
So mathematically, all these ideas I think are related.
Sara Walker (1:07:59.480)
I think a lot of people are thinking about this
Lex Fridman (1:08:00.680)
from different perspectives.
Lex Fridman (1:08:02.280)
And then constructor theory that David Deutsch
Lex Fridman (1:08:04.440)
and Chiara Marletto have been developing
Sara Walker (1:08:05.960)
is a totally different angle on it,
Lex Fridman (1:08:07.560)
but I think getting at some similar ideas.
Lex Fridman (1:08:09.120)
So it's a really interesting time right now, I think,
Lex Fridman (1:08:11.200)
for the frontiers of physics and how it's relating
Sara Walker (1:08:13.680)
to maybe deeper principles about what life is.
Lex Fridman (1:08:15.920)
So short answer, yes.
Sara Walker (1:08:17.120)
Long winded answer, rewind.
Lex Fridman (1:08:20.760)
Can we talk about aliens?
Sara Walker (1:08:22.760)
Anytime.
Lex Fridman (1:08:25.600)
So one, I think one interesting way to sneak up
Sara Walker (1:08:28.920)
on the question of what is life is to ask
Lex Fridman (1:08:33.240)
what should we look for in alien life?
Sara Walker (1:08:37.840)
If we were to look out into our galaxy and into the universe
Lex Fridman (1:08:42.440)
and come up with a framework of how to detect alien life,
Lex Fridman (1:08:47.440)
what should we be looking for?
Lex Fridman (1:08:49.600)
Is there like set of rules, like it's both the tools
Lex Fridman (1:08:55.400)
and the tools that are service sensors
Lex Fridman (1:08:59.000)
for certain kind of properties of life.
Lex Fridman (1:09:01.640)
So what should we look for in alien life?
Lex Fridman (1:09:05.400)
Yeah, so we have a paper actually coming out on Monday,
Sara Walker (1:09:08.000)
which is collaboration.
Lex Fridman (1:09:09.600)
It's actually really Lee Cronin's lab,
Lex Fridman (1:09:11.640)
but my group worked with him on it
Lex Fridman (1:09:12.920)
and we're working on the theory,
Sara Walker (1:09:13.840)
which is this idea that we should look for life
Lex Fridman (1:09:18.040)
as high assembly objects.
Lex Fridman (1:09:20.280)
What we mean by that is,
Lex Fridman (1:09:22.120)
which is actually observationally measurable.
Lex Fridman (1:09:24.360)
And this is one of the reasons that I started working
Lex Fridman (1:09:26.120)
with Lee on these ideas is because being a theorist,
Sara Walker (1:09:28.760)
it's easy to work in a vacuum.
Lex Fridman (1:09:29.920)
It's very hard to connect abstract ideas
Sara Walker (1:09:32.520)
about the nature of life to anything
Lex Fridman (1:09:34.120)
that's experimentally tractable.
Lex Fridman (1:09:36.800)
But what his lab has been able to do is develop this method
Lex Fridman (1:09:41.080)
where they look at a molecule
Lex Fridman (1:09:43.120)
and they break it apart into all its component parts.
Lex Fridman (1:09:46.160)
And so you say you used to have
Sara Walker (1:09:47.040)
some elementary building blocks
Lex Fridman (1:09:48.400)
and you can build up all the ways of putting those together
Sara Walker (1:09:51.160)
to make the original object.
Lex Fridman (1:09:52.680)
And then you look for the shortest path in that space.
Lex Fridman (1:09:55.240)
And you say that's sort of the assembly number
Lex Fridman (1:09:59.120)
associated to that object.
Lex Fridman (1:10:00.920)
And if that number is higher,
Lex Fridman (1:10:02.880)
it assumes that a longer causal history
Sara Walker (1:10:05.840)
is necessary to produce that object
Lex Fridman (1:10:07.480)
or more information is necessary to specify
Sara Walker (1:10:09.600)
the creation of that object in the universe.
Lex Fridman (1:10:11.440)
Now, that kind of idea at a superficial level
Sara Walker (1:10:14.160)
has existed for a long time.
Lex Fridman (1:10:15.800)
That kind of idea as a physical observable of molecules
Sara Walker (1:10:19.200)
is completely novel.
Lex Fridman (1:10:20.800)
And what his lab has been able to show
Sara Walker (1:10:22.800)
is that if you look at a bunch of samples
Lex Fridman (1:10:24.520)
of nonbiological things and biological things,
Sara Walker (1:10:26.800)
there's this kind of threshold of assembly
Lex Fridman (1:10:31.320)
where as far as the experimental evidence is
Lex Fridman (1:10:34.880)
and also your intuitive intuition would suggest
Lex Fridman (1:10:38.040)
that nonbiological systems don't produce things
Sara Walker (1:10:41.160)
with high assembly number.
Lex Fridman (1:10:43.160)
So this goes back to the idea
Sara Walker (1:10:44.680)
like a protein is not gonna spontaneously fluctuate
Lex Fridman (1:10:47.040)
into existence on the surface of Mars.
Sara Walker (1:10:48.680)
It requires an evolutionary process
Lex Fridman (1:10:50.120)
and a biological architecture to produce a protein.
Sara Walker (1:10:52.640)
You generalize that argument,
Lex Fridman (1:10:54.480)
a complex molecule or a cup or a desk ornament
Sara Walker (1:10:58.800)
in this sort of abstract idea of assembly spaces
Lex Fridman (1:11:01.960)
as being the causal history of objects.
Lex Fridman (1:11:04.560)
And you can talk about the shortest path
Lex Fridman (1:11:06.240)
from elementary objects to an object
Sara Walker (1:11:08.440)
given an elementary set of operations.
Lex Fridman (1:11:10.960)
And you can experimentally measure that with mass spec.
Lex Fridman (1:11:14.240)
And that's basically the sort of the idea.
Lex Fridman (1:11:16.640)
That's really fascinating.
Sara Walker (1:11:17.640)
I can't get out of my head.
Lex Fridman (1:11:19.040)
I'd start imagining Legos
Lex Fridman (1:11:20.840)
and all the Legos I've ever built and how many steps,
Lex Fridman (1:11:23.320)
what is the shortest path to the final little Lego castles?
Lex Fridman (1:11:28.440)
So then like asking about going to look for alien life,
Lex Fridman (1:11:31.800)
the idea is most of the instruments that NASA builds,
Sara Walker (1:11:35.560)
for example, or any of the space agencies
Lex Fridman (1:11:37.460)
looking for life in the universe
Lex Fridman (1:11:38.580)
are looking for chemical correlates of life, right?
Lex Fridman (1:11:41.980)
But here we have something
Sara Walker (1:11:43.360)
that is based on properties of molecules.
Lex Fridman (1:11:46.280)
It's not a chemical correlate, it's agnostic.
Sara Walker (1:11:49.120)
It doesn't care about the molecule.
Lex Fridman (1:11:50.520)
It cares about what is the history
Lex Fridman (1:11:53.760)
necessary to produce this molecule?
Lex Fridman (1:11:56.300)
How complex is it in terms of how much time is needing,
Lex Fridman (1:11:58.760)
how much information is required to produce it?
Lex Fridman (1:12:00.840)
So when you observe a thing on another planet,
Sara Walker (1:12:04.180)
you're essentially,
Lex Fridman (1:12:06.480)
the process looks like a reverse engineering,
Sara Walker (1:12:08.520)
trying to figure out what is the shortest path
Lex Fridman (1:12:10.480)
to create that thing.
Sara Walker (1:12:11.600)
Yeah, so most, yeah, and I would say most,
Lex Fridman (1:12:14.280)
like most examples of biology or technology
Lex Fridman (1:12:16.680)
don't take the shortest path, right?
Lex Fridman (1:12:18.080)
But the shortest path is a bound on how hard it is
Sara Walker (1:12:20.120)
for the universe to make that.
Lex Fridman (1:12:21.640)
Yeah, and I guess what you and Lee are saying
Sara Walker (1:12:25.080)
that there's a heuristic,
Lex Fridman (1:12:26.560)
that's a good metric for like better perhaps
Sara Walker (1:12:30.280)
than chemical correlates.
Lex Fridman (1:12:31.600)
Yes, because it doesn't, it's not contingent
Sara Walker (1:12:34.640)
on looking for the chemistry of life on earth,
Lex Fridman (1:12:37.480)
on other planets.
Lex Fridman (1:12:38.960)
And it also has a deeper explanatory framework
Lex Fridman (1:12:42.040)
associated to it,
Sara Walker (1:12:43.360)
as far as the kind of theory that we're trying to develop
Lex Fridman (1:12:45.720)
associated to what life is.
Lex Fridman (1:12:47.320)
And I think this is one of the problems I have
Lex Fridman (1:12:48.940)
in my field personally in astrobiology
Sara Walker (1:12:51.680)
is people observe something on earth,
Lex Fridman (1:12:53.960)
say oxygen in the atmosphere or an amino acid in a cell,
Lex Fridman (1:12:58.520)
and then they say, let's go look for that on another planet.
Lex Fridman (1:13:02.280)
Let's look for oxygen on exoplanets
Sara Walker (1:13:04.080)
or let's look for amino acids on Mars.
Lex Fridman (1:13:06.360)
And then they assume that's a way of looking for life
Sara Walker (1:13:12.140)
or even phosphine on Venus.
Lex Fridman (1:13:13.560)
But you know, like there's all these examples
Sara Walker (1:13:15.240)
of let's look for one molecule.
Lex Fridman (1:13:17.240)
A molecule is not life.
Sara Walker (1:13:18.440)
Life is a system that patterns particular structures
Lex Fridman (1:13:21.840)
into matter.
Sara Walker (1:13:22.680)
That's like, that's what it is.
Lex Fridman (1:13:24.460)
And it doesn't care what molecules are there.
Sara Walker (1:13:26.760)
It's something about the patterns and that structure
Lex Fridman (1:13:29.160)
and that history.
Lex Fridman (1:13:31.200)
And if you're looking for a molecule,
Lex Fridman (1:13:33.220)
you're not testing any hypotheses
Sara Walker (1:13:34.680)
about the nature of what life is.
Lex Fridman (1:13:36.160)
It doesn't tell me anything.
Sara Walker (1:13:37.440)
If we discover oxygen on an exoplanet
Lex Fridman (1:13:39.000)
about what kind of life is there,
Sara Walker (1:13:40.200)
just oxygen on an exoplanet.
Lex Fridman (1:13:42.040)
It's not, there's, I guess I think like,
Sara Walker (1:13:45.480)
when you think about the question,
Lex Fridman (1:13:46.640)
are we alone in the universe?
Sara Walker (1:13:47.800)
That's a pretty fricking deep question.
Lex Fridman (1:13:49.520)
It should have a fricking deep answer.
Sara Walker (1:13:51.040)
It shouldn't just be, there's a molecule on an exoplanet.
Lex Fridman (1:13:53.000)
Wow, we solved the problem.
Sara Walker (1:13:54.520)
It should tell us something meaningful about our existence.
Lex Fridman (1:13:56.560)
And I feel like we've fallen short
Sara Walker (1:13:59.000)
on how we're searching for life
Lex Fridman (1:14:01.200)
in terms of actually searching for things like us
Sara Walker (1:14:05.260)
in this kind of deeper way.
Lex Fridman (1:14:08.320)
But how do you do that initial kind of,
Sara Walker (1:14:10.360)
say I'm walking down the street
Lex Fridman (1:14:12.060)
and I'm looking for that double take test of like,
Lex Fridman (1:14:15.520)
like what the hell is that?
Lex Fridman (1:14:17.180)
Like that initial, like how do we look for
Sara Walker (1:14:22.220)
the possibility of weirdness
Lex Fridman (1:14:24.160)
or the possibility of high assembly number?
Sara Walker (1:14:26.480)
Well, yeah.
Lex Fridman (1:14:27.320)
Like what would aliens look like
Lex Fridman (1:14:29.680)
if they don't have two eyes and are green?
Lex Fridman (1:14:32.760)
If I knew, I wouldn't probably already solve the problem.
Sara Walker (1:14:35.520)
Right, there's another Nobel Prize in there somewhere.
Lex Fridman (1:14:37.640)
Yeah, somewhere in there.
Sara Walker (1:14:39.880)
Well, I think it's kind of,
Lex Fridman (1:14:41.280)
so there is a bias here, right?
Lex Fridman (1:14:43.160)
So we've evolved to recognize life on earth, right?
Lex Fridman (1:14:45.920)
Like I, you know, children at a very early age
Sara Walker (1:14:48.600)
can tell the difference between a puppy and a plant
Lex Fridman (1:14:50.640)
and then the plant and a chair, for example.
Sara Walker (1:14:53.400)
You know, like it just, it seems innate.
Lex Fridman (1:14:55.720)
And so I think, and also because we're life,
Sara Walker (1:14:59.920)
you know, I think like there's this implicit bias
Lex Fridman (1:15:02.560)
that we should know it when we see it
Lex Fridman (1:15:03.880)
and it should be completely obvious to us.
Lex Fridman (1:15:06.780)
But there are a lot of features of our universe
Sara Walker (1:15:08.940)
that are not completely obvious to us.
Lex Fridman (1:15:10.380)
Like the fact that this table is made of atoms
Lex Fridman (1:15:12.380)
and that I'm sitting
Lex Fridman (1:15:13.720)
in a gravitational potential well right now.
Lex Fridman (1:15:16.080)
And I guess my point with this is,
Lex Fridman (1:15:19.440)
I think life is much less obvious than we think it is.
Lex Fridman (1:15:23.240)
And so it could be in many more forms
Lex Fridman (1:15:25.280)
than we think it is.
Lex Fridman (1:15:27.080)
And I guess this goes back to the point
Lex Fridman (1:15:28.720)
about being open minded
Sara Walker (1:15:30.000)
that we may not know what alien life looks like.
Lex Fridman (1:15:33.000)
It might not even be possible to interact with alien life
Sara Walker (1:15:35.480)
because maybe something about, you know,
Lex Fridman (1:15:38.520)
our informational lineage, it makes it impossible
Sara Walker (1:15:41.240)
for information from an alien to be copied to us.
Lex Fridman (1:15:43.880)
Therefore there's no, you know,
Lex Fridman (1:15:46.040)
so to speak communication channel.
Lex Fridman (1:15:47.800)
And I don't mean, you know, verbal communication,
Sara Walker (1:15:49.840)
just it's not in our observational space.
Lex Fridman (1:15:52.960)
Like, you know, there's fundamental questions
Sara Walker (1:15:56.240)
about why we observe the universe in position
Lex Fridman (1:15:58.120)
rather than momentum, but we also, you know,
Sara Walker (1:16:00.800)
observe it in terms of certain informational patterns
Lex Fridman (1:16:03.120)
and things like that's what our brain constructs
Lex Fridman (1:16:04.980)
and maybe aliens just interact
Lex Fridman (1:16:07.280)
with a different part of reality than we do.
Sara Walker (1:16:08.640)
That's wildly speculative, but I think, I think.
Lex Fridman (1:16:12.000)
But it's possible.
Sara Walker (1:16:12.840)
It's possible and I think it's consistent with the physics.
Lex Fridman (1:16:15.140)
So I think the best ways we can ask questions
Sara Walker (1:16:17.160)
are about life and chemistry
Lex Fridman (1:16:19.600)
and asking questions about
Sara Walker (1:16:20.880)
if information is a real physical thing,
Lex Fridman (1:16:23.360)
what would its signatures be in matter
Lex Fridman (1:16:26.900)
and how do we recognize those?
Lex Fridman (1:16:28.960)
And I think the ones that are most obvious
Sara Walker (1:16:31.540)
are the ones I've already articulated.
Lex Fridman (1:16:33.080)
You have these objects that seem completely improbable
Sara Walker (1:16:35.680)
for the universe to produce
Lex Fridman (1:16:36.900)
because the universe doesn't have the design
Sara Walker (1:16:39.120)
of that object in the laws.
Lex Fridman (1:16:40.960)
So therefore an object had to evolve.
Sara Walker (1:16:44.500)
We talk, we call it evolution,
Lex Fridman (1:16:46.720)
but it had to be produced by the universe
Sara Walker (1:16:48.480)
that then had all of the possible tasks
Lex Fridman (1:16:51.360)
to make that object specified.
Sara Walker (1:16:54.680)
I mean, there's some,
Lex Fridman (1:16:55.520)
like there's an engineering question here of,
Sara Walker (1:16:59.120)
are there sensors we can create that can give us,
Lex Fridman (1:17:03.400)
can help us discover certain pockets
Lex Fridman (1:17:05.720)
of high assemblies aliens?
Lex Fridman (1:17:08.440)
Like, I mean, there is a hope
Sara Walker (1:17:12.120)
setting dogs and chairs aside,
Lex Fridman (1:17:14.640)
there's a hope that visually we could detect,
Sara Walker (1:17:19.480)
like, because our universe,
Lex Fridman (1:17:22.880)
I mean, at least the way we look at it now,
Sara Walker (1:17:24.480)
like this three dimensional like space time,
Lex Fridman (1:17:27.240)
we can visually comprehend it.
Sara Walker (1:17:29.360)
It's interesting to think like,
Lex Fridman (1:17:31.280)
if we got to hang out,
Sara Walker (1:17:33.040)
if there's an alien in this room,
Lex Fridman (1:17:35.920)
like would we be able to detect it with our current sensors?
Sara Walker (1:17:39.360)
Not the fancy kinds, but like web cam.
Lex Fridman (1:17:41.960)
Like say standing over there.
Sara Walker (1:17:43.320)
Yeah, standing over there
Lex Fridman (1:17:44.440)
or maybe like in this carpet,
Lex Fridman (1:17:45.880)
see there's all these kinds of patterns, right?
Lex Fridman (1:17:48.200)
I don't know if this carpet is an alien.
Sara Walker (1:17:52.880)
Well, so I see what you're saying.
Lex Fridman (1:17:56.200)
So assembly theory is pretty general.
Sara Walker (1:17:57.800)
Like, I mean, we've been applying it to molecules
Lex Fridman (1:18:00.040)
because it makes sense to apply it to molecules,
Lex Fridman (1:18:02.160)
but it's supposed to explain life,
Lex Fridman (1:18:06.160)
like the physics of life.
Lex Fridman (1:18:07.200)
So it should explain the things in this room
Lex Fridman (1:18:09.280)
in addition to molecules.
Lex Fridman (1:18:11.280)
So I guess, and you can apply it to images and things.
Lex Fridman (1:18:14.640)
So I guess the idea you could explore
Sara Walker (1:18:18.600)
is just looking at everything on planet earth
Lex Fridman (1:18:21.280)
in terms of its assembly structure
Lex Fridman (1:18:23.200)
and then looking for things
Lex Fridman (1:18:24.960)
that aren't part of our biological lineage.
Sara Walker (1:18:27.080)
If they have high assembly, they might be aliens on earth.
Lex Fridman (1:18:29.440)
I mean, that is a very kind of rigorous
Sara Walker (1:18:31.320)
computer vision question.
Lex Fridman (1:18:32.320)
Can we visually, is there a strong correlation
Sara Walker (1:18:36.640)
between certain kind of high assembly objects
Lex Fridman (1:18:38.600)
when they get to the scale
Sara Walker (1:18:39.880)
where they're visually observable
Lex Fridman (1:18:42.080)
and some, like when it's say projected onto a 2D plane,
Lex Fridman (1:18:47.240)
can we figure out something?
Lex Fridman (1:18:49.720)
I'm glad you brought up the computer vision point
Sara Walker (1:18:51.480)
because for a while I had this kind of thought in my mind
Lex Fridman (1:18:53.560)
that we can't even see ourselves clearly.
Lex Fridman (1:18:55.200)
So one of the things,
Lex Fridman (1:18:56.520)
people are worried about artificial intelligence
Sara Walker (1:18:57.960)
for a lot of reasons,
Lex Fridman (1:18:58.800)
but I think it's really fascinating
Sara Walker (1:18:59.880)
because it's like the first time in history
Lex Fridman (1:19:03.320)
that we're building a system
Sara Walker (1:19:04.440)
that can help us understand ourselves.
Lex Fridman (1:19:06.360)
So like, people talk about AI physics,
Lex Fridman (1:19:08.560)
but like, when I look at another person,
Lex Fridman (1:19:12.520)
I don't see them as a 4 billion year lineage,
Lex Fridman (1:19:15.400)
but that's what they are.
Lex Fridman (1:19:16.360)
And so is everything here, right?
Lex Fridman (1:19:18.160)
So imagine that we built artificial systems
Lex Fridman (1:19:21.440)
that could actually see that feature of us,
Lex Fridman (1:19:24.280)
what else would they see?
Lex Fridman (1:19:26.600)
And I think that's what you're asking.
Lex Fridman (1:19:28.680)
And I think that would be so cool.
Lex Fridman (1:19:31.840)
I want that to happen,
Lex Fridman (1:19:35.360)
but I think we're a little ways off from it, but yeah.
Lex Fridman (1:19:38.600)
We're going there, I hope.
Sara Walker (1:19:40.200)
Okay, let me ask you, I apologize ahead of time,
Lex Fridman (1:19:43.400)
but let me ask you the internet question.
Lex Fridman (1:19:45.160)
So you're a physicist,
Lex Fridman (1:19:46.200)
you ask rigorous questions about the physics of existence
Lex Fridman (1:19:49.640)
and these models of high assembly objects.
Lex Fridman (1:19:52.840)
Now, when the internet would see an alien,
Sara Walker (1:19:55.160)
they would ask two questions.
Lex Fridman (1:19:56.440)
One, can I eat it?
Lex Fridman (1:19:58.080)
And two, can I have sex with it?
Lex Fridman (1:19:59.960)
Yes.
Sara Walker (1:20:00.800)
So, the internet is.
Lex Fridman (1:20:02.440)
All the existential questions,
Sara Walker (1:20:04.560)
those are very important ones.
Lex Fridman (1:20:05.400)
The internet is very sophisticated.
Sara Walker (1:20:07.400)
It really is, it's gotten our basal cognition pretty good.
Lex Fridman (1:20:10.600)
So you kind of mentioned that it's very difficult.
Sara Walker (1:20:12.600)
It's possible that we may not be
Lex Fridman (1:20:14.360)
even able to communicate with it.
Sara Walker (1:20:16.080)
Right, I think the internet has more hope than we do.
Lex Fridman (1:20:18.560)
Yeah, it's a hopeful place, yes.
Lex Fridman (1:20:21.040)
Do you think in terms of interacting
Lex Fridman (1:20:23.680)
on this very primal level of sharing resources,
Lex Fridman (1:20:27.720)
like what would aliens eat?
Lex Fridman (1:20:28.880)
What would we eat?
Lex Fridman (1:20:29.880)
Would we eat the same thing?
Lex Fridman (1:20:31.400)
Could we potentially eat each other?
Sara Walker (1:20:33.880)
One person eats the other, or the aliens eat us.
Lex Fridman (1:20:37.240)
And the same thing with not sex in general,
Sara Walker (1:20:39.960)
or reproduction, but genetically mixing stuff.
Lex Fridman (1:20:42.360)
Like, would we be able to mix genetic information?
Lex Fridman (1:20:46.560)
Maybe not genetic, but maybe information, right?
Lex Fridman (1:20:48.760)
And I think part of your question is like,
Lex Fridman (1:20:50.520)
so if you think of life as like this history
Lex Fridman (1:20:54.200)
of events that happen in the universe,
Sara Walker (1:20:55.600)
like there's this question of like,
Lex Fridman (1:20:56.960)
how divergent are those histories, right?
Lex Fridman (1:20:59.320)
So when we get to the scale of technology,
Lex Fridman (1:21:00.920)
it's possible to imagine,
Sara Walker (1:21:02.920)
although we can't even do it.
Lex Fridman (1:21:04.080)
Like imagine all the possible technologies
Sara Walker (1:21:05.720)
that could exist in the universe.
Lex Fridman (1:21:06.840)
But if you think about all the possible chemistries,
Sara Walker (1:21:08.600)
somehow that seems like a lower dimensional space
Lex Fridman (1:21:10.840)
and a lower set of possibilities.
Lex Fridman (1:21:12.720)
So it might be that like when we interact with aliens,
Lex Fridman (1:21:15.840)
we do have to go back to those more basal levels
Lex Fridman (1:21:19.080)
to figure out sort of what the map is, right?
Lex Fridman (1:21:22.680)
Like the sort of where we have a common history.
Sara Walker (1:21:25.640)
We must have a common history somewhere in the universe,
Lex Fridman (1:21:28.800)
but in order to be able to actually interact
Sara Walker (1:21:31.360)
in a meaningful way, you have to have some shared history.
Lex Fridman (1:21:33.560)
I mean, the reason we can exchange genetic information
Sara Walker (1:21:35.560)
in each other's food or eat each other as food
Lex Fridman (1:21:39.080)
is because we have a shared history.
Lex Fridman (1:21:40.720)
So we have to find that shared history.
Lex Fridman (1:21:42.680)
We have to find the common ancestor
Sara Walker (1:21:44.240)
in this causality map, the causality tree.
Lex Fridman (1:21:47.160)
Yes, and we have a last universal common ancestor
Sara Walker (1:21:49.600)
for all life on earth, which I think is sort of the nexus
Lex Fridman (1:21:51.840)
of that causality map for life on earth.
Lex Fridman (1:21:54.080)
But the question is where would other aliens
Lex Fridman (1:21:56.880)
diverge on that map?
Sara Walker (1:21:58.200)
That's really interesting.
Lex Fridman (1:21:59.040)
And I mean, so say there's a lot of aliens out there
Sara Walker (1:22:03.600)
in the universe, each set of organisms
Lex Fridman (1:22:07.000)
will probably have like a number, you know,
Sara Walker (1:22:08.800)
like Erdos number of like how far,
Lex Fridman (1:22:13.120)
like how far our common ancestor is.
Lex Fridman (1:22:15.960)
And so the closer the common ancestor, like it is on earth,
Lex Fridman (1:22:19.600)
the more likely we are to be able
Sara Walker (1:22:22.280)
to have sexual reproduction.
Lex Fridman (1:22:24.120)
Well, it's like sort of like humans having common culture
Lex Fridman (1:22:26.080)
and languages, right?
Lex Fridman (1:22:27.120)
Yeah, exactly.
Sara Walker (1:22:27.960)
Yeah, it might take a lot of work though with an alien
Lex Fridman (1:22:32.360)
cause you really have to get over a language barrier.
Sara Walker (1:22:35.600)
Oh boy.
Lex Fridman (1:22:36.640)
So it's communication, it's resources.
Sara Walker (1:22:40.080)
I mean, it's all the whole,
Lex Fridman (1:22:43.480)
and I think tied into that is the questions
Sara Walker (1:22:46.320)
of like who's going to harm who.
Lex Fridman (1:22:48.160)
Right.
Lex Fridman (1:22:49.000)
And actually definitions of harm.
Lex Fridman (1:22:49.840)
And whether your parents approve,
Sara Walker (1:22:50.920)
you know, all those kind of questions.
Lex Fridman (1:22:52.800)
Whether the common ancestor approves.
Sara Walker (1:22:54.600)
Yeah, that's just very true.
Lex Fridman (1:22:58.040)
How many alien civilizations do you think are out there?
Sara Walker (1:23:01.760)
I don't have intuition for that,
Lex Fridman (1:23:04.960)
which I have always thought was deeply intriguing.
Sara Walker (1:23:07.440)
So, and part of this, I mean, I say it specifically
Lex Fridman (1:23:11.440)
as I don't have intuition for that
Sara Walker (1:23:12.720)
because it's like one of those questions
Lex Fridman (1:23:14.160)
that you feel around for a while
Lex Fridman (1:23:15.480)
and you really just, you can't see it
Lex Fridman (1:23:19.360)
even though it might be right there.
Lex Fridman (1:23:20.880)
And in that sense, it's a little like
Lex Fridman (1:23:24.200)
the quantum to classical can transition.
Sara Walker (1:23:25.840)
You're like really talking about
Lex Fridman (1:23:26.760)
two different kinds of physics.
Lex Fridman (1:23:28.000)
And I think that's kind of part of the problem.
Lex Fridman (1:23:29.360)
Once we understand the physics,
Sara Walker (1:23:30.400)
that question might become more meaningful.
Lex Fridman (1:23:33.040)
But there's also this other issue,
Lex Fridman (1:23:36.320)
and this was really instilled on me
Lex Fridman (1:23:37.720)
by my mentor, Paul Davies, when I was a postdoc,
Sara Walker (1:23:39.720)
because he always talks about how, you know,
Lex Fridman (1:23:42.240)
whether aliens are common or rare is kind of just,
Sara Walker (1:23:45.800)
you know, it like, you know, it follows a wave of popularity
Lex Fridman (1:23:49.200)
and it just depends on like the mood of, you know,
Lex Fridman (1:23:51.320)
what the culture is at the time.
Lex Fridman (1:23:53.160)
And I always thought that was kind of
Sara Walker (1:23:54.480)
an intriguing observation, but also there's this,
Lex Fridman (1:23:56.880)
you know, set of points about
Sara Walker (1:23:58.360)
if you go by the observational evidence,
Lex Fridman (1:23:59.920)
which we're supposed to do as scientists, right?
Sara Walker (1:24:03.960)
You know, we have evidence of us
Lex Fridman (1:24:08.600)
and one origin of life event from which we emerged.
Lex Fridman (1:24:11.560)
And people wanna make arguments
Lex Fridman (1:24:13.080)
that because that event was rapid
Sara Walker (1:24:15.720)
or because there's other planets
Lex Fridman (1:24:17.240)
that have properties similar to ours,
Sara Walker (1:24:18.720)
that that event should be common.
Lex Fridman (1:24:20.400)
But you actually can't reason on that
Sara Walker (1:24:22.040)
because our existence observing that event
Lex Fridman (1:24:23.720)
is contingent on that event happening,
Sara Walker (1:24:25.720)
which means it could have been completely improbable
Lex Fridman (1:24:27.800)
or very common.
Lex Fridman (1:24:29.360)
And Brandon Carter, like clearly articulated that
Lex Fridman (1:24:31.800)
in terms of anthropic arguments a few decades ago.
Lex Fridman (1:24:35.400)
So there is this kind of issue
Lex Fridman (1:24:37.960)
that we have to contend with dealing with life
Sara Walker (1:24:39.800)
that's closer to home than we have to deal with
Lex Fridman (1:24:41.880)
with any other problems in physics,
Sara Walker (1:24:43.600)
which we're talking about the physics of ourselves.
Lex Fridman (1:24:45.800)
And when you're asking about the origin of life event,
Sara Walker (1:24:47.640)
that event happening in the universe,
Lex Fridman (1:24:48.960)
at least as like our existence is contingent on it.
Lex Fridman (1:24:52.520)
And so you can think about sort of fine tuning arguments
Lex Fridman (1:24:55.800)
that way too.
Sara Walker (1:24:56.640)
So, but the sort of otter part of it is like,
Lex Fridman (1:25:00.000)
when I think about how likely it is,
Sara Walker (1:25:03.200)
I think it's because we don't understand this mechanism yet
Lex Fridman (1:25:06.320)
about how information can be generated spontaneously
Sara Walker (1:25:10.800)
that I like, cause I can't see that physics clearly yet,
Lex Fridman (1:25:13.800)
even though I have a lot of, you know,
Sara Walker (1:25:15.720)
like some things around the space of it in my mind,
Lex Fridman (1:25:18.680)
I can't articulate how likely that process is.
Lex Fridman (1:25:22.480)
So my honest answer is, I don't know.
Lex Fridman (1:25:24.200)
And sometimes that feels like a cop out,
Lex Fridman (1:25:25.920)
but I feel like that's a more honest answer
Lex Fridman (1:25:27.400)
and a more meaningful way of making progress
Sara Walker (1:25:29.800)
than what a lot of people wanna do, which is say,
Lex Fridman (1:25:32.760)
oh, well, we have a one in 10 chance of having
Sara Walker (1:25:34.760)
on an exoplanet with Earth like properties
Lex Fridman (1:25:36.480)
because there's lots of Earth like planets out there
Lex Fridman (1:25:38.760)
and life happened fast on Earth.
Lex Fridman (1:25:40.360)
Well, so I have kind of a follow up question,
Lex Fridman (1:25:42.960)
but as a side comment, what I really am enjoying
Lex Fridman (1:25:46.640)
about the way you're talking about human beings
Sara Walker (1:25:48.800)
is you always say, and not to make yourself conscious
Lex Fridman (1:25:51.240)
about it, cause I really, really enjoy it.
Sara Walker (1:25:53.080)
You say we, you don't say humans.
Lex Fridman (1:25:57.360)
You say, cause oftentimes like, you know,
Sara Walker (1:26:00.200)
I don't know, evolutionary biologists
Lex Fridman (1:26:01.760)
will kind of put yourself out as an observer,
Lex Fridman (1:26:05.400)
but it's kind of fascinating to think that you as a human
Lex Fridman (1:26:09.040)
are struggling about your own origins.
Sara Walker (1:26:11.080)
Yes, that's the problem.
Lex Fridman (1:26:12.720)
And yeah, and I think, I don't do that deliberately,
Lex Fridman (1:26:17.160)
but I do think that way.
Lex Fridman (1:26:18.440)
And this is sort of the inversion
Sara Walker (1:26:19.760)
from the logic of physics because physics
Lex Fridman (1:26:21.600)
as it's always been constructed has treated us
Sara Walker (1:26:24.280)
as external observers of the universe.
Lex Fridman (1:26:26.360)
And we are not part of the universe.
Lex Fridman (1:26:27.680)
And this is why the problem of life,
Lex Fridman (1:26:29.360)
I think demands completely new thinking
Sara Walker (1:26:31.320)
because we have to think about ourselves
Lex Fridman (1:26:33.600)
as minds that exist in the universe
Lex Fridman (1:26:35.600)
and are at this particular moment in history
Lex Fridman (1:26:37.800)
and looking out at the things around us
Lex Fridman (1:26:39.680)
and trying to understand what we are inside the system,
Lex Fridman (1:26:42.720)
not outside the system.
Sara Walker (1:26:43.840)
We don't have descriptions at a fundamental level
Lex Fridman (1:26:46.800)
that describe us as inside the system.
Lex Fridman (1:26:48.840)
And this was my problem with cellular automata also.
Lex Fridman (1:26:51.280)
You're always an external observer for a cellular automata.
Sara Walker (1:26:54.200)
You're not in the system.
Lex Fridman (1:26:55.280)
What does the cellular automata look like from the inside?
Sara Walker (1:26:58.920)
I think you just broke my brain with that question.
Lex Fridman (1:27:00.880)
Exactly.
Lex Fridman (1:27:01.720)
But that's the fundamental.
Lex Fridman (1:27:02.560)
I thought about that for a long time, but.
Sara Walker (1:27:03.400)
I'm gonna, yeah, that's a really clean formulation
Lex Fridman (1:27:08.400)
of a very fundamental question,
Sara Walker (1:27:10.640)
because you can only, to understand cellular automata,
Lex Fridman (1:27:13.640)
you have to be inside of it.
Lex Fridman (1:27:16.560)
But as a human, sort of a poetic, romantic question,
Lex Fridman (1:27:20.880)
does it make you sad?
Lex Fridman (1:27:22.120)
Does it make you hopeful whether we're alone or not?
Lex Fridman (1:27:27.360)
Like in the different possible versions of that,
Sara Walker (1:27:31.040)
if we're the highest assembly object in the entire universe,
Lex Fridman (1:27:36.160)
does that give you?
Sara Walker (1:27:37.000)
At this moment in time, maybe.
Lex Fridman (1:27:38.120)
At this moment in the causal.
Sara Walker (1:27:39.880)
Cause we may, I assume we have a future.
Lex Fridman (1:27:41.880)
Well, we definitely have a future.
Sara Walker (1:27:43.520)
The question is where that future decreases the assembly.
Lex Fridman (1:27:47.920)
Like it could be where at the peak, or we could be just.
Sara Walker (1:27:52.880)
That would be inconsistent with the physics in my mind.
Lex Fridman (1:27:55.800)
But so I should give a caveat.
Sara Walker (1:27:59.160)
I've given the caveat that I'm biased as a physicist,
Lex Fridman (1:28:01.560)
but I'm also biased as an eternal optimist.
Lex Fridman (1:28:03.560)
So pretty much all of my modes of operation
Lex Fridman (1:28:06.560)
for building theories about the world
Sara Walker (1:28:08.120)
are not like an Occam's razor,
Lex Fridman (1:28:10.160)
what's the simplest explanation,
Lex Fridman (1:28:11.640)
but what's the most optimistic explanation.
Lex Fridman (1:28:14.440)
And part of the reason for that
Sara Walker (1:28:16.240)
is if you really think explanations have causal power,
Lex Fridman (1:28:20.720)
in the sense that our,
Sara Walker (1:28:22.080)
like the fact that we have theories about the world
Lex Fridman (1:28:23.720)
has enabled technologies
Lex Fridman (1:28:24.960)
and physically transform the world around us.
Lex Fridman (1:28:27.560)
I think I have to take seriously that
Sara Walker (1:28:29.120)
as a part of the physics I wanna describe
Lex Fridman (1:28:31.400)
and try to build theories of reality
Sara Walker (1:28:35.880)
that are optimistic about what's coming next
Lex Fridman (1:28:37.800)
because the theories are in part
Sara Walker (1:28:39.080)
the causes of what comes next.
Lex Fridman (1:28:42.320)
So there could be a physics of hope
Sara Walker (1:28:45.000)
or physics of optimism in there too.
Lex Fridman (1:28:46.880)
Yes.
Sara Walker (1:28:48.000)
Is that seems like also,
Lex Fridman (1:28:50.800)
I mean, optimism does seem to be a kind of engine
Sara Walker (1:28:53.920)
that results in innovation.
Lex Fridman (1:28:56.200)
Yes.
Lex Fridman (1:28:57.040)
So this is like,
Lex Fridman (1:28:58.320)
why the hell are we trying to come up with new stuff?
Sara Walker (1:29:02.040)
Oh, so I made this point about thinking life
Lex Fridman (1:29:04.840)
is the physics of existence.
Lex Fridman (1:29:06.120)
And it's not just the physics of existence,
Lex Fridman (1:29:07.800)
it's the physics of more things existing.
Lex Fridman (1:29:11.360)
So I think one of these drives of like.
Lex Fridman (1:29:12.800)
Creativity.
Sara Walker (1:29:13.640)
Yeah, creativity, like optimism.
Lex Fridman (1:29:16.320)
So if you like, people like entropy.
Sara Walker (1:29:18.640)
I don't like entropy as it was formulated in the 1800s.
Lex Fridman (1:29:21.360)
I think it's an antiquated concept,
Lex Fridman (1:29:22.760)
but this idea of maximizing
Lex Fridman (1:29:26.320)
over the possible number of states that could exist.
Sara Walker (1:29:28.880)
Imagine the universe is actually trying to maximize
Lex Fridman (1:29:31.080)
over the number of things that could physically exist.
Lex Fridman (1:29:33.360)
What would be the best way to do that?
Lex Fridman (1:29:34.680)
The best way to do that
Sara Walker (1:29:35.520)
would be evolve intelligent technological things
Lex Fridman (1:29:37.760)
that could explore that space.
Sara Walker (1:29:41.760)
So, okay, that's talking about alien life
Lex Fridman (1:29:43.840)
out there in the universe,
Lex Fridman (1:29:45.080)
but you've also earlier in the conversation mentioned
Lex Fridman (1:29:48.560)
the shadow biosphere.
Lex Fridman (1:29:50.200)
So is it possible that we have weird life here on earth
Lex Fridman (1:29:56.320)
that we're just not,
Sara Walker (1:29:58.440)
like even in a high assembly formulation of life,
Lex Fridman (1:30:02.200)
that we're just not paying attention to?
Sara Walker (1:30:05.680)
We're blind to.
Lex Fridman (1:30:07.040)
Like life we're potentially able to detect,
Lex Fridman (1:30:09.480)
but we're blind to.
Lex Fridman (1:30:10.520)
And maybe you could say, what is the shadow biosphere?
Sara Walker (1:30:12.320)
Sure, sure.
Lex Fridman (1:30:13.320)
Yeah, the shadow biosphere is this idea
Sara Walker (1:30:15.160)
that there might've been other original life events
Lex Fridman (1:30:17.960)
that happened on earth that were independent
Sara Walker (1:30:21.000)
from the original life event that led to us
Lex Fridman (1:30:24.040)
and all of the life that we know on earth.
Lex Fridman (1:30:26.360)
And therefore there could be aliens
Lex Fridman (1:30:29.360)
in the sense they have a different origin event.
Sara Walker (1:30:32.120)
Living among us.
Lex Fridman (1:30:34.600)
And it was proposed by a number of people,
Lex Fridman (1:30:38.240)
but one of them was Paul Davies
Lex Fridman (1:30:39.920)
that I mentioned earlier is my mentor.
Lex Fridman (1:30:41.160)
And he has a really cute way of saying
Lex Fridman (1:30:42.960)
that aliens could be right under our noses
Sara Walker (1:30:44.760)
or even in our noses.
Lex Fridman (1:30:48.680)
With a British accent, it sounds better.
Lex Fridman (1:30:50.360)
But anyway, so the idea is like,
Lex Fridman (1:30:53.760)
it could literally be anywhere around us.
Lex Fridman (1:30:56.440)
And if you think actually about the discovery
Lex Fridman (1:30:58.240)
of like viruses and bacteria,
Sara Walker (1:31:00.240)
for a long time they were kind of a shadow biosphere.
Lex Fridman (1:31:02.400)
It was life that was around us, but invisible.
Lex Fridman (1:31:08.240)
But this takes it a little bit further
Lex Fridman (1:31:09.800)
and saying that all of those examples,
Sara Walker (1:31:12.000)
viruses, bacteria and everything that we've discovered so far
Lex Fridman (1:31:14.960)
has this common ancestry
Lex Fridman (1:31:16.160)
and the last universal common ancestor of life on earth.
Lex Fridman (1:31:18.520)
So maybe there was a different origin event
Lex Fridman (1:31:20.440)
and that life is weirder still and might be among us
Lex Fridman (1:31:24.480)
and we could find it.
Sara Walker (1:31:26.680)
We don't have to go out and the stars look for aliens
Lex Fridman (1:31:28.520)
just here on earth.
Lex Fridman (1:31:29.840)
Do you think that's a serious possibility
Lex Fridman (1:31:32.920)
that we should explore with the tools of science?
Sara Walker (1:31:35.200)
Like this should be a serious effort.
Lex Fridman (1:31:36.880)
I think yes and no.
Lex Fridman (1:31:39.560)
And I mean, yes, because I think it's a serious hypothesis
Lex Fridman (1:31:44.280)
and I think it's worth exploring.
Lex Fridman (1:31:46.360)
And it is certainly more economical
Lex Fridman (1:31:48.880)
to look for signs of alien life on earth
Sara Walker (1:31:52.080)
than it is to go and build spacecraft
Lex Fridman (1:31:54.200)
and send robots to other planets.
Lex Fridman (1:31:56.320)
And that was one of the reasons it was proposed is,
Lex Fridman (1:31:58.360)
well, if we do find an example of another original life
Sara Walker (1:32:01.120)
on earth, it's hugely informative
Lex Fridman (1:32:03.240)
because it means the origin of life is not a rare event.
Sara Walker (1:32:05.480)
If it happened twice on the same planet,
Lex Fridman (1:32:08.040)
that means it's probably pretty probable
Sara Walker (1:32:09.560)
given conditions are right.
Lex Fridman (1:32:11.680)
So it has huge potential scientific impact,
Sara Walker (1:32:14.160)
not to mention the fact that you might have like biochemistry
Lex Fridman (1:32:16.560)
and stuff that's informative for like medicine
Lex Fridman (1:32:18.400)
and stuff like that.
Lex Fridman (1:32:19.240)
But I think the thing for me that's challenging about it
Lex Fridman (1:32:23.320)
and this really comes from my own work,
Lex Fridman (1:32:24.720)
like thinking about life as a planetary scale process
Lex Fridman (1:32:28.920)
and also trying to understand
Lex Fridman (1:32:31.000)
sometimes what I call like the statistical mechanics
Sara Walker (1:32:33.120)
of biochemistry, but large scale statistical patterns
Lex Fridman (1:32:35.680)
in the chemistry that life uses on earth.
Sara Walker (1:32:38.480)
There are a lot of regularities there
Lex Fridman (1:32:40.720)
and life does seem to have planetary scale organization
Sara Walker (1:32:45.720)
that's consistent even with some of the patterns
Lex Fridman (1:32:47.880)
that we see at the individual scale.
Lex Fridman (1:32:49.240)
So if you think life is a planetary scale phenomenon
Lex Fridman (1:32:51.920)
and the chemistry of life has to be sort of not just,
Sara Walker (1:32:55.800)
it's not, an individual is not necessarily
Lex Fridman (1:32:58.080)
the fundamental unit of life, right?
Sara Walker (1:33:00.080)
The fundamental unit of life
Lex Fridman (1:33:01.240)
is these informational lineages and they're kind of,
Sara Walker (1:33:05.280)
they intersect over spatial scales.
Lex Fridman (1:33:08.320)
So everything on earth is kind of related
Sara Walker (1:33:10.400)
by the common causal history.
Lex Fridman (1:33:12.520)
So it's hard for me based on the way I think
Sara Walker (1:33:15.200)
about the physics and also some of the stuff
Lex Fridman (1:33:18.040)
that my group has done to really think
Sara Walker (1:33:19.960)
that there could be evidence
Lex Fridman (1:33:23.000)
or there could be a second sample of life on earth.
Lex Fridman (1:33:25.160)
But I think there are ways
Lex Fridman (1:33:26.320)
that we need to be more concrete about that.
Lex Fridman (1:33:28.560)
And I have thought a little bit about like,
Lex Fridman (1:33:32.080)
like you can represent the chemistry
Sara Walker (1:33:33.480)
in an individual cell as a network.
Lex Fridman (1:33:35.680)
And then those networks, something my group has shown
Sara Walker (1:33:39.360)
actually scale with the same property.
Lex Fridman (1:33:42.520)
So ecosystems have the same properties
Sara Walker (1:33:43.920)
as individuals as planetary scale.
Lex Fridman (1:33:46.080)
And then you could imagine
Sara Walker (1:33:47.120)
if you had alien chemistry intermixed in there,
Lex Fridman (1:33:49.600)
that scaling would be broken.
Lex Fridman (1:33:50.960)
So if there's some robustness property
Lex Fridman (1:33:52.800)
or something associated to it,
Lex Fridman (1:33:54.560)
and you get alien chemistry in there,
Lex Fridman (1:33:56.040)
it just breaks everything.
Lex Fridman (1:33:57.120)
And you don't have a planetary ecosystem functioning
Lex Fridman (1:34:02.200)
and individuals functioning across all these scales.
Lex Fridman (1:34:04.600)
So I guess what I'm arguing
Lex Fridman (1:34:06.160)
is life is not a scale dependent phenomenon.
Sara Walker (1:34:08.400)
It's not just cellular life.
Lex Fridman (1:34:10.240)
So if you have a shadow biosphere,
Sara Walker (1:34:11.520)
it has to be integrated with all of these other scales.
Lex Fridman (1:34:13.560)
And that would lose the meaning
Sara Walker (1:34:16.160)
of the word shadow biosphere, I guess.
Lex Fridman (1:34:17.480)
I think so, yeah.
Lex Fridman (1:34:18.520)
So it's an open question, right?
Lex Fridman (1:34:21.280)
And I think it would tell us a lot.
Lex Fridman (1:34:23.160)
So there has been very minimal effort
Lex Fridman (1:34:25.560)
of people to look for a shadow biosphere.
Lex Fridman (1:34:28.160)
But then the question,
Lex Fridman (1:34:29.200)
it could be possible that there's like
Sara Walker (1:34:32.440)
sufficiently distinct planets within one planet,
Lex Fridman (1:34:37.160)
meaning like environments within one planet.
Sara Walker (1:34:40.000)
Like, I don't know.
Lex Fridman (1:34:42.520)
I've been looking recently
Sara Walker (1:34:45.160)
because of having a chat with Catherine Duclair
Lex Fridman (1:34:47.600)
about Io, the moon of Jupiter,
Sara Walker (1:34:49.240)
that's like all volcanoes and volcanoes are bad ass.
Lex Fridman (1:34:51.600)
But like, imagining life inside volcanoes, right?
Sara Walker (1:34:58.760)
It seems like sufficiently chemically different
Lex Fridman (1:35:03.000)
like to be living in the darkness
Sara Walker (1:35:05.440)
where there's a lot of heat
Lex Fridman (1:35:06.640)
and maybe you could have different Earths on a planet.
Sara Walker (1:35:10.960)
Or like if you go deep enough in the crust,
Lex Fridman (1:35:12.680)
maybe there's like a layer where there's no life.
Lex Fridman (1:35:14.360)
And then there's suddenly life again.
Lex Fridman (1:35:15.840)
And maybe those, you know, lizard men
Sara Walker (1:35:18.880)
or whatever they are that people dream about
Lex Fridman (1:35:20.760)
are really down there.
Sara Walker (1:35:22.640)
I know that's a little flippant,
Lex Fridman (1:35:24.120)
but really like there could be like chemical cycles
Sara Walker (1:35:26.760)
deep in the Earth's crust that might be alive
Lex Fridman (1:35:29.000)
and are completely distinct
Sara Walker (1:35:30.240)
in chemical origin to surface life.
Lex Fridman (1:35:33.400)
Right, that they wouldn't be interacting with each other.
Sara Walker (1:35:35.400)
Yeah, and that's one of the proposals
Lex Fridman (1:35:36.600)
for the shadow biosphere is like,
Sara Walker (1:35:38.080)
sometimes people talk about it as being geologically
Lex Fridman (1:35:40.840)
or geographically distinct that it might be,
Sara Walker (1:35:43.640)
you know, you have no life for this region
Lex Fridman (1:35:45.160)
and then a different example.
Lex Fridman (1:35:46.680)
And then sometimes people talk about it
Lex Fridman (1:35:47.880)
being chemically distinct,
Sara Walker (1:35:49.280)
that the chemistry is sufficiently different,
Lex Fridman (1:35:51.560)
that it's completely orthogonal
Sara Walker (1:35:52.880)
or non interacting with our chemistry.
Lex Fridman (1:35:54.400)
It seems to me at least the chemistry
Sara Walker (1:35:55.920)
is a more powerful boundary than geographic.
Lex Fridman (1:36:02.440)
It just seems like life finds a way literally to travel.
Sara Walker (1:36:06.320)
Yeah, it does.
Lex Fridman (1:36:08.200)
What do you think about all these UFO sightings?
Lex Fridman (1:36:11.440)
So to me, it's really inspiring.
Lex Fridman (1:36:14.000)
It's yet another localized way to dream
Sara Walker (1:36:18.120)
about the mysterious that is out there.
Lex Fridman (1:36:21.560)
Yeah, so I've actually been more intrigued
Sara Walker (1:36:24.560)
by the cultural phenomena UFOs
Lex Fridman (1:36:26.480)
than the phenomena UFOs themselves,
Sara Walker (1:36:28.360)
because I think it's intriguing about how
Lex Fridman (1:36:32.040)
we are preparing ourselves mentally
Sara Walker (1:36:35.400)
for understanding others
Lex Fridman (1:36:37.520)
and how we have thought about that historically
Lex Fridman (1:36:39.640)
and what the sort of modern incarnations of that are.
Lex Fridman (1:36:44.280)
It's more like, I want an explanation for us.
Sara Walker (1:36:47.440)
That's my motivation.
Lex Fridman (1:36:48.640)
And having some, you know,
Sara Walker (1:36:50.440)
streaks across the sky or something
Lex Fridman (1:36:52.120)
and saying that's aliens,
Sara Walker (1:36:53.120)
it doesn't tell you anything.
Lex Fridman (1:36:55.720)
So unless you have a deeper explanation
Lex Fridman (1:36:57.520)
and you have, you know, more lines of,
Lex Fridman (1:37:00.400)
you know, where is this gonna take us in the future?
Sara Walker (1:37:02.680)
It's just not as interesting to me
Lex Fridman (1:37:04.720)
as the problem of understanding life itself
Lex Fridman (1:37:06.760)
and aliens as a more general phenomenon.
Lex Fridman (1:37:08.720)
I do think it's, just as you said,
Sara Walker (1:37:11.000)
a good way to psychologically and sociologically
Lex Fridman (1:37:13.920)
prepare ourselves to sort of like,
Lex Fridman (1:37:15.840)
what would that look like?
Lex Fridman (1:37:17.440)
And very importantly,
Sara Walker (1:37:18.680)
which is what a lot of people talk about politically,
Lex Fridman (1:37:21.440)
sort of there's this idea from the,
Lex Fridman (1:37:24.480)
so I came from the Soviet Union of like the Cold War
Lex Fridman (1:37:27.640)
and we have to hide secrets.
Sara Walker (1:37:30.080)
There's some way in us searching for life on other planets
Lex Fridman (1:37:33.440)
or our searching for life in general,
Sara Walker (1:37:36.000)
the way we've done government in the past,
Lex Fridman (1:37:40.840)
we tend to think of all new things
Sara Walker (1:37:43.280)
as potential military secrets,
Lex Fridman (1:37:45.160)
so we want to hide them.
Lex Fridman (1:37:46.880)
And one of the ways that people kind of look
Lex Fridman (1:37:49.240)
at UFO sightings is like,
Sara Walker (1:37:51.680)
like maybe we shouldn't hide this stuff.
Lex Fridman (1:37:53.520)
Like what is the government hiding?
Sara Walker (1:37:55.080)
I think that's a really, you know,
Lex Fridman (1:37:57.920)
in one sense it's a conspiratorial question,
Lex Fridman (1:38:00.120)
but I think in another,
Lex Fridman (1:38:02.400)
it's an inspiration to change the way we do government
Sara Walker (1:38:07.320)
to where secrets don't,
Lex Fridman (1:38:09.960)
maybe there are times when you want to keep secrets
Sara Walker (1:38:12.440)
as military secrets,
Lex Fridman (1:38:13.440)
but maybe we need to release a lot more stuff
Lex Fridman (1:38:15.920)
and see us as a human species as together
Lex Fridman (1:38:19.040)
in this whole search.
Sara Walker (1:38:20.160)
Yeah, the public engagement part there
Lex Fridman (1:38:21.720)
is really interesting.
Lex Fridman (1:38:23.840)
And it's almost like a challenge
Lex Fridman (1:38:25.680)
to the way we've done stuff in the past
Sara Walker (1:38:27.920)
in terms of keeping secrets when they're not,
Lex Fridman (1:38:30.320)
so like the first step,
Sara Walker (1:38:33.280)
if you don't know how something works,
Lex Fridman (1:38:36.560)
if there's a mysterious thing,
Sara Walker (1:38:38.440)
the first instinct should not be like, let's hide it.
Lex Fridman (1:38:42.080)
Let's put it in the closet.
Lex Fridman (1:38:44.040)
So that the Chinese or the Russian government
Lex Fridman (1:38:46.000)
or whatever government doesn't find it.
Sara Walker (1:38:48.840)
Maybe the first instinct should be, let's understand it.
Lex Fridman (1:38:53.080)
Perhaps let's understand it together.
Sara Walker (1:38:54.720)
Right.
Lex Fridman (1:38:55.760)
No, I think that's good.
Lex Fridman (1:38:57.000)
And something I realized recently
Lex Fridman (1:38:58.720)
that I never thought was gonna be a problem,
Lex Fridman (1:39:00.120)
but I think this actually helps with quite a bit
Lex Fridman (1:39:02.640)
is because so many people nowadays
Sara Walker (1:39:05.800)
believe we've already made contact,
Lex Fridman (1:39:08.160)
that as an astrobiologist,
Sara Walker (1:39:10.840)
if we actually want to understand life and make contact,
Lex Fridman (1:39:14.600)
we kind of have to deconstruct the narratives
Sara Walker (1:39:17.360)
we've already built from ourselves
Lex Fridman (1:39:18.600)
and kind of unteach ourselves
Sara Walker (1:39:19.920)
that we've learned about aliens and then reteach ourselves.
Lex Fridman (1:39:22.640)
So there's this really interesting sort of dialogue there
Lex Fridman (1:39:26.040)
and making it open to the public
Lex Fridman (1:39:27.840)
that they actually have to think critically about it
Lex Fridman (1:39:29.560)
and they see the evidence for themselves,
Lex Fridman (1:39:30.960)
I think is really important for that process.
Sara Walker (1:39:33.800)
Yeah, that aliens might be way weirder than we can imagine.
Lex Fridman (1:39:38.200)
Yes.
Sara Walker (1:39:39.320)
Yes, I'm pretty sure they're probably weirder
Lex Fridman (1:39:41.920)
than we can imagine.
Sara Walker (1:39:44.120)
Okay, we've in 2020 and still living through a pandemic,
Lex Fridman (1:39:49.240)
setting the political and all those kinds of things aside,
Sara Walker (1:39:54.120)
I've always found viruses fascinating
Lex Fridman (1:39:58.200)
as dynamical systems, I was gonna say living systems,
Lex Fridman (1:40:03.200)
but I've always kind of thought of them as living,
Lex Fridman (1:40:07.160)
but that's a whole nother kind of discussion.
Sara Walker (1:40:09.560)
Maybe it'd be great to put that on the table.
Lex Fridman (1:40:13.280)
One, do you find viruses beautiful slash terrifying?
Lex Fridman (1:40:17.520)
And two, do you think they're living things
Lex Fridman (1:40:21.560)
or there's some aspect to them per our discussion of life
Lex Fridman (1:40:25.800)
that makes them living?
Lex Fridman (1:40:27.760)
I mean, living in a pandemic saying viruses are beautiful
Sara Walker (1:40:30.120)
is probably a hard thing,
Lex Fridman (1:40:30.960)
but I do find them beautiful to a degree.
Sara Walker (1:40:34.520)
I think even in the sense of mediating a global pandemic,
Lex Fridman (1:40:39.760)
there's something like deeply intriguing there
Lex Fridman (1:40:41.440)
because these are tiny, tiny little things, right?
Lex Fridman (1:40:46.200)
And yet they can essentially cause a seizure
Sara Walker (1:40:52.520)
or handicap an entire civilization at a global scale.
Lex Fridman (1:40:55.840)
So just that intersection between
Sara Walker (1:40:58.520)
our perceived invincibility and our susceptibility to things
Lex Fridman (1:41:02.640)
and also the interaction across scales of those things
Sara Walker (1:41:04.840)
is just a really amazing feature of our world.
Lex Fridman (1:41:09.280)
Most technology, whether it's viruses or AI
Sara Walker (1:41:12.680)
that can scale in an exponential way,
Lex Fridman (1:41:16.440)
like kind of run as opposed to like,
Sara Walker (1:41:21.360)
one thing makes another thing makes another thing,
Lex Fridman (1:41:24.800)
it's one thing makes two things
Lex Fridman (1:41:26.520)
and those two things make four things.
Lex Fridman (1:41:28.720)
Like that kind of process
Sara Walker (1:41:32.200)
also seems to be fundamental to life.
Lex Fridman (1:41:34.800)
Yes.
Lex Fridman (1:41:35.640)
And it's terrifying because in a matter of,
Lex Fridman (1:41:40.000)
in a very short time scale, it can,
Sara Walker (1:41:45.320)
if it's good at being life, whatever that is,
Lex Fridman (1:41:48.760)
it can quickly overtake the other competing forms of life.
Sara Walker (1:41:52.520)
Right.
Lex Fridman (1:41:53.520)
And that's scary both for AI and for viruses.
Lex Fridman (1:41:57.680)
And it seems like understanding these processes
Lex Fridman (1:42:00.560)
that are underlying viruses.
Lex Fridman (1:42:02.000)
And I don't mean like on the virology or biology side,
Lex Fridman (1:42:05.240)
but on some kind of more computational physics perspective
Sara Walker (1:42:09.800)
as we've been talking about,
Lex Fridman (1:42:11.320)
seems to be really important to figure out
Lex Fridman (1:42:15.680)
how humans can survive.
Lex Fridman (1:42:19.120)
Right.
Sara Walker (1:42:20.520)
Along with this kind of life
Lex Fridman (1:42:23.960)
and perhaps becoming a multi planetary species
Sara Walker (1:42:26.840)
is a part of that.
Lex Fridman (1:42:28.680)
Like there's no, maybe like we'll figure out
Sara Walker (1:42:31.640)
from a physics perspective is like,
Lex Fridman (1:42:33.280)
there's no way any living system
Sara Walker (1:42:38.040)
can be stable for prolonged period of time
Lex Fridman (1:42:40.760)
and survive unless it expands exponentially throughout.
Sara Walker (1:42:43.680)
Like we have to multiply.
Lex Fridman (1:42:46.200)
Otherwise anything that doesn't multiply exponentially
Sara Walker (1:42:49.880)
will die eventually.
Lex Fridman (1:42:50.840)
Maybe that's a fundamental law.
Sara Walker (1:42:54.120)
Maybe, I don't know.
Lex Fridman (1:42:56.000)
I always get really bothered by these Darwinian narratives
Sara Walker (1:42:58.920)
that are like the fittest replicator wins and things.
Lex Fridman (1:43:01.720)
And I don't, I just don't feel like
Sara Walker (1:43:03.120)
that's exactly what's going on.
Lex Fridman (1:43:04.720)
I think like the copying of information
Sara Walker (1:43:06.440)
is sort of ancillary to this other process of creativity.
Lex Fridman (1:43:10.440)
Right, so like the drive is actually,
Sara Walker (1:43:12.360)
the drive is creativity,
Lex Fridman (1:43:13.720)
but if you wanna keep the creativity
Sara Walker (1:43:16.000)
that's existed in the past,
Lex Fridman (1:43:17.480)
it has to be copied into the future.
Lex Fridman (1:43:19.600)
So replication, like if you, so that for me is,
Lex Fridman (1:43:23.240)
so I had this set of arguments with Michael Lockman
Lex Fridman (1:43:26.280)
and Lee Cronin about the like life being about persistence.
Lex Fridman (1:43:29.520)
They thought it was about persistence
Lex Fridman (1:43:30.720)
and like survival of the fittest kind of thing.
Lex Fridman (1:43:32.320)
And I'm like, no, it's about existence.
Sara Walker (1:43:33.840)
It's like, cause when you're talking about that,
Lex Fridman (1:43:36.680)
it's easy to say that in retrospect,
Sara Walker (1:43:38.640)
you can post select on the things that survived
Lex Fridman (1:43:40.800)
and then say why they survived,
Lex Fridman (1:43:43.000)
but you can't do that going forward.
Lex Fridman (1:43:46.280)
That's really profound
Sara Walker (1:43:47.960)
that survival is just a nice little side effect feature
Lex Fridman (1:43:52.160)
of maximizing creativity, but it doesn't need to be there.
Sara Walker (1:43:56.560)
Yeah, I like that. That's really beautiful.
Lex Fridman (1:43:58.520)
Yeah, I know, like I said, I like optimistic theories.
Sara Walker (1:44:01.800)
Well, I don't know if that's optimistic.
Lex Fridman (1:44:03.120)
That could be terrifying to people because,
Sara Walker (1:44:06.120)
because a system that maximizes creativity
Lex Fridman (1:44:09.360)
may very quickly get rid of humans for some reason,
Sara Walker (1:44:13.040)
if it comes up with some other creative,
Lex Fridman (1:44:15.920)
I mean, forms of existence, right?
Sara Walker (1:44:20.000)
This is the AI thing is like the moment you have an AI system
Lex Fridman (1:44:24.240)
that can flourish in the space of ideas
Sara Walker (1:44:28.960)
or in some other space much more effectively than humans.
Lex Fridman (1:44:33.360)
And it's sufficiently integrated into the physical space
Sara Walker (1:44:36.600)
to be able to modify the environment.
Lex Fridman (1:44:39.160)
I think we'll just be like
Sara Walker (1:44:40.280)
the core genetic architecture or something.
Lex Fridman (1:44:42.040)
We'll be like the DNA for AI, right?
Sara Walker (1:44:44.400)
It's like, we haven't lost the past informational
Lex Fridman (1:44:46.440)
architectures on this planet.
Sara Walker (1:44:47.720)
They're still there.
Lex Fridman (1:44:49.840)
Yeah, so the AI will use our brains in some part
Sara Walker (1:44:53.840)
to like ride, like accelerate the exchange of ideas.
Lex Fridman (1:44:58.000)
That's the neural language dream is that,
Sara Walker (1:45:00.960)
well, the humans will be still around
Lex Fridman (1:45:03.480)
because you're saying architecture.
Sara Walker (1:45:05.320)
Yeah, but I don't even think
Lex Fridman (1:45:06.400)
they necessarily need to tap into our brains.
Sara Walker (1:45:08.320)
I mean, just collectively, we do interesting things.
Lex Fridman (1:45:10.400)
What if they were just using like the patterns
Lex Fridman (1:45:12.160)
in our communication or something?
Lex Fridman (1:45:14.720)
Oh, without controlling it, just observing?
Sara Walker (1:45:18.080)
Well, I don't know.
Lex Fridman (1:45:19.000)
In what sense do you control the chemistry
Lex Fridman (1:45:20.720)
happening in your body?
Lex Fridman (1:45:24.160)
Yeah.
Sara Walker (1:45:25.200)
I mean, obviously I don't know.
Lex Fridman (1:45:27.320)
I'm just, like the way I look at, like people look at AI
Lex Fridman (1:45:31.280)
and then they look at this thing that's bigger than us
Lex Fridman (1:45:33.480)
and is coming in the future and is smarter than us.
Lex Fridman (1:45:36.040)
And I think though that looking at the past history
Lex Fridman (1:45:38.640)
of life on the planet and what information
Sara Walker (1:45:40.600)
has been doing for the last 4 billion years
Lex Fridman (1:45:42.240)
is probably very informative to asking questions
Sara Walker (1:45:44.840)
about what's coming next.
Lex Fridman (1:45:47.760)
And I don't,
Sara Walker (1:45:50.560)
one is planetary scale transitions are really important
Lex Fridman (1:45:53.360)
for new phases.
Lex Fridman (1:45:54.320)
So the global internet and sort of global integration
Lex Fridman (1:45:56.600)
of our technology, I think is an important thing.
Lex Fridman (1:45:58.440)
So that's again, life is a planetary scale phenomenon
Lex Fridman (1:46:01.040)
but we're an integrated component of that phenomenon.
Sara Walker (1:46:03.280)
I don't really see that the technology
Lex Fridman (1:46:04.920)
is gonna replace us in that way.
Sara Walker (1:46:07.040)
It's just gonna keep scaffolding and building.
Lex Fridman (1:46:09.800)
And I also don't have an idea
Sara Walker (1:46:11.320)
that we're gonna build AI in a box.
Lex Fridman (1:46:12.680)
I think AI is gonna emerge.
Sara Walker (1:46:14.440)
AGI to me is a planetary scale phenomena
Lex Fridman (1:46:17.120)
that's gonna emerge from our technology.
Sara Walker (1:46:19.880)
Planetary scale phenomena.
Lex Fridman (1:46:22.240)
But do you think an AGI is not distinct from humans?
Sara Walker (1:46:26.120)
The whole package.
Lex Fridman (1:46:27.440)
The whole package, yeah.
Sara Walker (1:46:28.280)
Comes as a planetary scale phenomena.
Lex Fridman (1:46:30.080)
And that goes back to the fact that like,
Sara Walker (1:46:31.640)
you were asking questions about you as an individual.
Lex Fridman (1:46:34.840)
Like, what are you as an individual?
Sara Walker (1:46:36.120)
You're like a packet of information
Lex Fridman (1:46:38.040)
that exists in the particular physical thing that is you.
Sara Walker (1:46:41.320)
We're all just packets of information.
Lex Fridman (1:46:43.680)
And some of us are aggregates in certain ways
Lex Fridman (1:46:45.600)
but it's all just kind of exchanging
Lex Fridman (1:46:47.080)
and propagating, right?
Lex Fridman (1:46:48.200)
And processing.
Lex Fridman (1:46:49.600)
Is your packet of information
Sara Walker (1:46:52.600)
that you've continually referred to as Sarah
Lex Fridman (1:46:56.000)
afraid of the dissipation of the death of that packet?
Lex Fridman (1:47:01.160)
Are you afraid of death?
Lex Fridman (1:47:03.000)
Do you ponder death?
Sara Walker (1:47:04.640)
Does death have meaning in this process
Lex Fridman (1:47:07.240)
of creativity?
Sara Walker (1:47:09.240)
I think I have the natural biological urge
Lex Fridman (1:47:12.280)
that everyone has to fear death.
Sara Walker (1:47:15.480)
I think the thing that I think is interesting
Lex Fridman (1:47:17.760)
is if I think about it rationally,
Sara Walker (1:47:20.160)
I'm not necessarily afraid of death for me
Lex Fridman (1:47:22.040)
because I won't be aware of being dead.
Lex Fridman (1:47:25.240)
But I am afraid like for my kids
Lex Fridman (1:47:26.680)
because it matters to them if I die.
Lex Fridman (1:47:29.720)
So again, like I think death becomes more significant
Lex Fridman (1:47:33.680)
as a collective property, not as an individual one.
Sara Walker (1:47:37.280)
Yeah, but isn't there something to fear
Lex Fridman (1:47:39.240)
about the fact that the way,
Sara Walker (1:47:42.880)
like the creative,
Lex Fridman (1:47:46.920)
the complexity of information
Sara Walker (1:47:48.520)
that's been like created in you.
Lex Fridman (1:47:51.040)
Yeah.
Sara Walker (1:47:52.040)
The fact that it kind of breaks apart and disappears.
Lex Fridman (1:47:57.640)
It doesn't, but I don't think it disappears.
Sara Walker (1:47:59.560)
It's just not me anymore.
Lex Fridman (1:48:00.960)
Right, but that process of it being not you anymore,
Lex Fridman (1:48:06.120)
that doesn't scare you?
Lex Fridman (1:48:07.960)
Of course it does.
Sara Walker (1:48:08.960)
The mystery of it.
Lex Fridman (1:48:09.800)
I mean, the...
Sara Walker (1:48:10.640)
Yeah, but I guess I'm heartened by the fact
Lex Fridman (1:48:12.320)
that there will be some imprints of the fact
Sara Walker (1:48:14.000)
that I existed still in the universe after I leave it.
Lex Fridman (1:48:16.960)
Yeah, but there'll be a...
Sara Walker (1:48:18.360)
Okay, but...
Lex Fridman (1:48:19.200)
And also that has to do with my perception of time, right?
Sara Walker (1:48:21.720)
So, I perceive time as flowing,
Lex Fridman (1:48:23.760)
but that might not be the case.
Sara Walker (1:48:26.800)
I mean, this is standard physicist comfort is,
Lex Fridman (1:48:29.960)
every moment exists and there's no...
Lex Fridman (1:48:33.560)
And the flow of time is just our perception of us changing.
Lex Fridman (1:48:41.040)
So, you can travel back in time and that's comforting?
Lex Fridman (1:48:43.400)
Like from a physicist's concept?
Lex Fridman (1:48:44.800)
No, no, no.
Sara Walker (1:48:45.640)
I'm not talking about traveling back in time.
Lex Fridman (1:48:46.800)
I'm just saying that the moments in the past still exist.
Sara Walker (1:48:50.400)
Now, whether the moments in the future exist or not
Lex Fridman (1:48:52.640)
is a different question.
Sara Walker (1:48:53.800)
That's not comforting to me in terms of death.
Lex Fridman (1:48:57.040)
The flow of time is not...
Sara Walker (1:48:58.960)
I think there's no comfort in the face of death
Lex Fridman (1:49:04.080)
for what we are because we like existing.
Lex Fridman (1:49:07.880)
And I think it's especially true if you love life
Lex Fridman (1:49:11.560)
and you love what life is.
Lex Fridman (1:49:13.680)
Do you think there's a certain sense in which
Lex Fridman (1:49:16.160)
the fear of death or the fear of nonexistence,
Sara Walker (1:49:19.120)
maybe fear is not the right word,
Lex Fridman (1:49:21.360)
is the actual very phenomena that gives birth to existence?
Sara Walker (1:49:26.360)
Like, death is fundamental.
Lex Fridman (1:49:28.480)
It just feels like freaking out, oh shit,
Sara Walker (1:49:31.560)
this ride ends is actually like the...
Lex Fridman (1:49:36.560)
That's the thing that gives birth to this whole thing.
Sara Walker (1:49:40.760)
Yeah.
Lex Fridman (1:49:41.600)
That like, it's constantly...
Sara Walker (1:49:45.080)
It's matter constantly freaking out about the fact
Lex Fridman (1:49:48.120)
that it's gonna be the most.
Sara Walker (1:49:48.960)
No, I think things like to exist.
Lex Fridman (1:49:51.080)
I think they wanna exist.
Sara Walker (1:49:51.920)
Yeah, there's a desire, whatever, to exist.
Lex Fridman (1:49:55.240)
Yeah.
Sara Walker (1:49:56.080)
There's a drive to exist
Lex Fridman (1:49:57.960)
and there's a drive for more things to exist.
Sara Walker (1:50:00.000)
I guess, yeah, I like existing.
Lex Fridman (1:50:03.000)
I like it a lot and I don't know it any other way.
Sara Walker (1:50:09.280)
See, I don't even know if I like existing.
Lex Fridman (1:50:11.960)
I think I really don't like not existing.
Sara Walker (1:50:14.520)
Yes.
Lex Fridman (1:50:15.360)
Yeah, that's true.
Sara Walker (1:50:17.440)
Yeah, maybe it's that.
Lex Fridman (1:50:19.760)
Some days I might like existing less than others.
Sara Walker (1:50:23.320)
Yes, but like, I think those are like surface feelings.
Lex Fridman (1:50:27.600)
Yeah, yeah.
Sara Walker (1:50:28.440)
It seems like there's something fundamental
Lex Fridman (1:50:29.880)
about wanting to exist.
Sara Walker (1:50:31.240)
No, I think that's right.
Lex Fridman (1:50:32.080)
But I think to your point that that might go back
Sara Walker (1:50:35.720)
to the more fundamental idea that, you know,
Lex Fridman (1:50:39.120)
if life is the physics of existence
Lex Fridman (1:50:40.640)
and maximizing existence, individual organisms,
Lex Fridman (1:50:43.040)
of course, wanna maximize their existence
Lex Fridman (1:50:45.520)
and everything, you know, like wants to exist.
Lex Fridman (1:50:48.000)
But I guess for me, the small comfort is
Sara Walker (1:50:50.560)
my existence matters to future existence.
Lex Fridman (1:50:54.480)
Speaking of future existence, is there advice
Sara Walker (1:50:57.320)
you can give to future pockets of existences,
Lex Fridman (1:51:00.880)
AKA young people, about life?
Sara Walker (1:51:04.160)
You've had, you've worn many hats.
Lex Fridman (1:51:07.240)
You've taken on some of the biggest problems
Sara Walker (1:51:09.120)
in the universe.
Lex Fridman (1:51:10.400)
Is there advice you can give to young people
Lex Fridman (1:51:13.000)
about life, about career, about existing?
Lex Fridman (1:51:17.280)
Yeah, maybe not about the last one.
Sara Walker (1:51:20.520)
You know, a lot of people ask me this question
Lex Fridman (1:51:23.400)
about like working on such hard problems,
Lex Fridman (1:51:25.880)
like how can you make a successful career out of that?
Lex Fridman (1:51:28.160)
But I think for me, it couldn't be otherwise.
Sara Walker (1:51:31.280)
Like I have to, to be fulfilled,
Lex Fridman (1:51:33.280)
you have to work on things you care about.
Lex Fridman (1:51:35.240)
And that's always kind of driven me.
Lex Fridman (1:51:36.840)
And that's been discipline, department,
Lex Fridman (1:51:41.720)
and sort of superficial level problem independent
Lex Fridman (1:51:44.880)
because I started at community college actually,
Lex Fridman (1:51:48.360)
and I was taking a physics class
Lex Fridman (1:51:49.680)
and I learned about magnetic monopoles
Lex Fridman (1:51:53.080)
and we didn't know if they existed in the universe,
Lex Fridman (1:51:55.440)
but we could predict them and we could go look for them.
Lex Fridman (1:51:57.880)
And I was so deeply intrigued by this idea
Lex Fridman (1:51:59.520)
that we had this mathematical formula to go look for things.
Lex Fridman (1:52:02.440)
And then I wanted to become a theoretical physicist
Lex Fridman (1:52:05.120)
because of that.
Lex Fridman (1:52:05.960)
But that actually wasn't my driving question.
Lex Fridman (1:52:07.680)
I realized my driving question is the nature
Sara Walker (1:52:10.600)
of the correspondence between our minds
Lex Fridman (1:52:12.120)
and physical reality and what we are.
Lex Fridman (1:52:14.360)
And that question is very deep,
Lex Fridman (1:52:16.480)
so you can work across a lot of fields doing that.
Lex Fridman (1:52:18.560)
But I think without that driving question,
Lex Fridman (1:52:20.040)
I never would have been able to do all the things
Sara Walker (1:52:22.280)
that I've done.
Lex Fridman (1:52:23.120)
It's really the passion that drives it.
Lex Fridman (1:52:25.080)
And usually when students ask me these kinds of questions,
Lex Fridman (1:52:28.480)
I tell them like, you have to find something
Sara Walker (1:52:31.800)
you really care about working on
Lex Fridman (1:52:33.240)
because if you don't really care about it,
Sara Walker (1:52:35.440)
A, you're not gonna be your best at it,
Lex Fridman (1:52:37.880)
and B, it's not gonna be worth your time.
Lex Fridman (1:52:39.800)
Why would you spend your time working on something
Lex Fridman (1:52:41.520)
you're not interested in?
Lex Fridman (1:52:43.040)
So find the driving questions.
Lex Fridman (1:52:44.760)
Yeah, find the driving question.
Sara Walker (1:52:46.000)
Find your passion.
Lex Fridman (1:52:47.480)
I mean, I think passion makes a huge difference
Sara Walker (1:52:49.440)
in terms of creativity, talent, and potential,
Lex Fridman (1:52:52.720)
and also being able to tolerate all the hard things
Sara Walker (1:52:55.040)
that come with any career or life.
Lex Fridman (1:52:57.880)
Yeah, I've had a bunch of moments in my life
Sara Walker (1:52:59.840)
where I've just been captivated
Lex Fridman (1:53:01.800)
by some beautiful phenomena.
Lex Fridman (1:53:03.200)
And I guess being rigorous about it
Lex Fridman (1:53:06.080)
and asking what is the question underlying this phenomena,
Sara Walker (1:53:09.520)
like robots bring a smile to my face
Lex Fridman (1:53:13.400)
and forming a question of like,
Lex Fridman (1:53:17.040)
why the hell is this so fascinating?
Lex Fridman (1:53:19.960)
Why is this, specifically the human robot
Sara Walker (1:53:23.200)
interaction question that something beautiful
Lex Fridman (1:53:27.040)
is brought to life when humans and robots interact,
Sara Walker (1:53:30.720)
understanding that deeply.
Lex Fridman (1:53:33.640)
It's like, okay, so this is gonna be my life work then.
Sara Walker (1:53:36.640)
I don't know what the hell it is,
Lex Fridman (1:53:37.760)
but that's what I wanna do.
Sara Walker (1:53:39.640)
Interesting.
Lex Fridman (1:53:40.480)
And doing that for whatever the hell gives you
Sara Walker (1:53:43.000)
that kind of feeling, I guess, is the point.
Lex Fridman (1:53:45.320)
Yeah.
Lex Fridman (1:53:46.520)
Am I allowed to ask you a question?
Lex Fridman (1:53:47.880)
Sure.
Sara Walker (1:53:48.720)
Okay.
Lex Fridman (1:53:49.800)
On that point,
Sara Walker (1:53:50.920)
because I had this colleague that suggested the idea
Lex Fridman (1:53:53.880)
that consciousness might be contagious.
Lex Fridman (1:53:56.160)
And so interacting with things,
Lex Fridman (1:53:58.240)
it's an interesting idea, right?
Lex Fridman (1:54:01.000)
So I'm wondering sort of the motivation there.
Lex Fridman (1:54:04.440)
Is it the motivation that you want more of the universe
Sara Walker (1:54:08.560)
to appreciate things the way we do
Lex Fridman (1:54:11.280)
and appreciate those interactions?
Sara Walker (1:54:12.760)
Or is it really more the enjoyment of the human
Lex Fridman (1:54:15.760)
in those interactions?
Lex Fridman (1:54:16.600)
Like, is it, do you know what I'm asking?
Lex Fridman (1:54:20.320)
Yeah, yeah.
Sara Walker (1:54:21.160)
See, I think consciousness is created
Lex Fridman (1:54:23.800)
in the interaction between things.
Sara Walker (1:54:27.520)
Yes, I agree.
Lex Fridman (1:54:28.360)
So the joy is in the creation of consciousness.
Sara Walker (1:54:31.160)
I see.
Lex Fridman (1:54:32.000)
I really like the idea that
Sara Walker (1:54:35.120)
it doesn't just have to be two humans
Lex Fridman (1:54:38.560)
creating consciousness together.
Sara Walker (1:54:40.080)
It could be humans and other entities.
Lex Fridman (1:54:43.400)
We talked offline about dogs and other pets and so on.
Sara Walker (1:54:46.520)
There's a magic, I mean, I've been calling it love.
Lex Fridman (1:54:49.720)
It's this beauty of the human experience that's created.
Lex Fridman (1:54:54.320)
And it just feels like fascinating that you could do that
Lex Fridman (1:54:58.200)
with a robotic system.
Sara Walker (1:55:00.560)
Right.
Lex Fridman (1:55:01.400)
And there's something really powerful, at least to me,
Sara Walker (1:55:06.880)
about engineering systems that allow you
Lex Fridman (1:55:10.400)
to create some of the magic of the human experience.
Sara Walker (1:55:12.560)
Cause then you get to understand what it takes,
Lex Fridman (1:55:15.440)
at least get inklings of what it takes
Sara Walker (1:55:17.920)
to create consciousness.
Lex Fridman (1:55:21.360)
And I don't get this, you know,
Sara Walker (1:55:24.280)
philosophers get really upset about this idea
Lex Fridman (1:55:26.240)
that sort of the illusion of consciousness is consciousness.
Lex Fridman (1:55:29.640)
But I really liked the idea of engineering systems
Lex Fridman (1:55:33.680)
that fool you into thinking they're conscious.
Sara Walker (1:55:37.240)
Right.
Lex Fridman (1:55:38.080)
Because that's sufficient to create the magical experience.
Sara Walker (1:55:41.880)
Right, because it's the interaction, yeah.
Lex Fridman (1:55:43.520)
It's the interaction, yeah.
Sara Walker (1:55:44.520)
Right.
Lex Fridman (1:55:45.360)
And this is the Russian hat I wear,
Sara Walker (1:55:47.600)
which is like, I think there's an ocean of loneliness
Lex Fridman (1:55:51.000)
in the world.
Sara Walker (1:55:51.920)
I think we're deeply lonely.
Lex Fridman (1:55:53.440)
We're not even allowing ourselves to acknowledge that.
Lex Fridman (1:55:57.200)
And I kind of think that's what love is between romantic love
Lex Fridman (1:56:00.800)
and friendship is two people kind of getting a little bit
Sara Walker (1:56:05.800)
like alleviating for brief moment.
Lex Fridman (1:56:11.400)
That loneliness.
Sara Walker (1:56:12.240)
That loneliness, but not, but we're not there.
Lex Fridman (1:56:15.280)
It's not the full aspect of that loneliness.
Sara Walker (1:56:17.920)
Like we're desperately alone.
Lex Fridman (1:56:19.360)
We're desperately afraid of nonexisting.
Sara Walker (1:56:22.560)
Right.
Lex Fridman (1:56:23.400)
I have that kind of sense.
Lex Fridman (1:56:24.560)
And I just want to explore that ocean of loneliness more.
Lex Fridman (1:56:28.160)
Right.
Sara Walker (1:56:29.000)
When engineering, like create a submarine
Lex Fridman (1:56:30.840)
that goes into the depth of that loneliness.
Lex Fridman (1:56:33.720)
So creating systems that can truly hear you.
Lex Fridman (1:56:36.560)
Right.
Lex Fridman (1:56:37.400)
And truly listen.
Lex Fridman (1:56:38.240)
Make the universe a less lonely place.
Sara Walker (1:56:39.800)
Exactly.
Lex Fridman (1:56:40.960)
Let me ask you about the meaning.
Sara Walker (1:56:43.160)
You've brought up why.
Lex Fridman (1:56:44.800)
Yeah.
Sara Walker (1:56:45.640)
The physics of why.
Lex Fridman (1:56:46.480)
What do you think is the meaning of our particular planets,
Lex Fridman (1:56:51.120)
set of existences and the universe in general?
Lex Fridman (1:56:56.120)
The meaning of life.
Sara Walker (1:56:57.040)
Yes.
Lex Fridman (1:56:57.880)
Someone once told me as a physicist,
Sara Walker (1:56:59.040)
I'm not allowed to ask why questions,
Lex Fridman (1:57:00.800)
but I don't believe that.
Lex Fridman (1:57:01.960)
So I think what we are is the creative process
Lex Fridman (1:57:10.240)
in the universe, I think.
Lex Fridman (1:57:11.400)
And for me, that's the meaning.
Lex Fridman (1:57:14.240)
The ability to create more possibilities
Lex Fridman (1:57:18.160)
and more things to exist.
Lex Fridman (1:57:19.480)
What is, Dostoevsky has the saying,
Sara Walker (1:57:23.760)
beauty will save the world.
Lex Fridman (1:57:25.760)
What is, is there a connection between creation and beauty?
Sara Walker (1:57:33.280)
I think so.
Lex Fridman (1:57:35.040)
So is that like, is beauty a correlate of creation?
Sara Walker (1:57:39.320)
It might be.
Lex Fridman (1:57:40.160)
I don't know.
Sara Walker (1:57:41.160)
I mean, why is it, you know,
Lex Fridman (1:57:43.280)
a lot of people have asked these kinds of questions,
Lex Fridman (1:57:44.720)
but like, why is it we have such an emotional response
Lex Fridman (1:57:47.200)
to intellectual activity or creativity?
Lex Fridman (1:57:49.800)
And that seems kind of a deep question to me.
Lex Fridman (1:57:52.440)
Like, it seems very intrinsic to what we are.
Lex Fridman (1:57:55.560)
So I do have an interest in the questions I ask
Lex Fridman (1:57:59.840)
because I think they're beautiful
Lex Fridman (1:58:01.240)
and I think the universe is beautiful.
Lex Fridman (1:58:02.880)
And I'm just so deeply fascinated
Sara Walker (1:58:06.360)
by the fact that I exist at all.
Lex Fridman (1:58:10.400)
And so maybe it's that, you know,
Sara Walker (1:58:13.920)
that intrinsic feeling of beauty
Lex Fridman (1:58:15.600)
that's in part driving, you know,
Sara Walker (1:58:17.400)
the physics of creating more things.
Lex Fridman (1:58:19.000)
So they could be deeply related in that way.
Sara Walker (1:58:22.080)
Well, I don't think there's a better way to end it.
Lex Fridman (1:58:24.680)
I think this conversation was beautiful.
Sara Walker (1:58:27.120)
Thank you so much for wasting
Lex Fridman (1:58:29.760)
all your valuable time with me today.
Sara Walker (1:58:31.920)
I really, really appreciate it, Sarah.
Lex Fridman (1:58:33.520)
This is an honor.
Sara Walker (1:58:34.360)
I hope we get the chance to talk again.
Lex Fridman (1:58:36.000)
I hope, like I mentioned to you offline,
Sara Walker (1:58:38.120)
we get a chance to talk with Lee.
Lex Fridman (1:58:39.560)
You guys have a beautiful, like, intellectual chemistry
Sara Walker (1:58:44.560)
that's fascinating to listen to.
Lex Fridman (1:58:45.760)
So I'm a huge fan of both of you
Lex Fridman (1:58:47.120)
and I can't wait to see what you do next.
Lex Fridman (1:58:49.440)
Thanks so much.
Sara Walker (1:58:50.280)
Great to be here.
Lex Fridman (1:58:51.320)
I am.
Sara Walker (1:58:52.880)
Thanks for listening to this conversation
Lex Fridman (1:58:54.400)
with Sarah Walker and thank you to Athletic Greens,
Sara Walker (1:58:57.680)
Nat Sweet, Blinkist, and Magic Spoon.
Lex Fridman (1:59:01.120)
Check them out in the description to support this podcast.
Lex Fridman (1:59:04.360)
And now let me leave you with some words
Lex Fridman (1:59:06.040)
from Robert Frost, one of my favorite poets.
Sara Walker (1:59:09.480)
In three words, I can sum up everything
Lex Fridman (1:59:11.640)
I've learned about life.
Sara Walker (1:59:13.560)
It goes on.
Lex Fridman (1:59:16.240)
Thank you for listening.
Sara Walker (1:59:17.200)
I hope to see you next time.
Lex Fridman (20:01.900)
once you come up with an answer to what is life,
Sara Walker (20:04.860)
will the words information and computation
Lex Fridman (20:07.180)
be in the paragraph that answer?
Sara Walker (20:08.660)
No, I don't think so.
Lex Fridman (20:09.500)
Oh, damn it, okay.
Lex Fridman (20:10.460)
I know, it doesn't help, does it?
Lex Fridman (20:11.800)
I know, I hate, actually I hate this about what I do
Sara Walker (20:14.000)
because it's so hard to communicate, right, with words.
Lex Fridman (20:16.380)
Like when you have words that are ideas
Sara Walker (20:20.500)
that have historically described one thing
Lex Fridman (20:22.700)
and you're trying to describe something
Sara Walker (20:24.200)
people haven't seen yet, and the words just don't fit.
Lex Fridman (20:27.900)
So what's wrong, is it too ambiguous, the word information?
Sara Walker (20:31.560)
We could switch to binary if you want.
Lex Fridman (20:33.380)
Yeah, no, I don't think it's binary either.
Sara Walker (20:35.220)
I think information's just loaded.
Lex Fridman (20:36.980)
I use it, so the other way I might talk about it
Sara Walker (20:39.260)
is the physics of causation, but I think that's worse
Lex Fridman (20:41.980)
because causation is even more loaded word
Sara Walker (20:43.940)
than information.
Lex Fridman (20:46.740)
So causation is fundamental, you think?
Sara Walker (20:48.780)
I do, yeah, and in some sense, I think the physics,
Lex Fridman (20:52.220)
so this is the really radical part,
Sara Walker (20:53.780)
some sense, like when I really think about it
Lex Fridman (20:55.500)
sort of most deeply, what I think life is
Sara Walker (20:58.460)
is actually the physics of existence,
Lex Fridman (21:00.140)
what gets to exist and why.
Lex Fridman (21:02.780)
And for simple elementary particles,
Lex Fridman (21:04.760)
that's not very complicated
Sara Walker (21:05.780)
because the interactions are simple,
Lex Fridman (21:06.940)
but for things like you and me and human civilizations,
Lex Fridman (21:11.060)
what comes next in the universe
Lex Fridman (21:13.500)
is really dependent on what came before,
Lex Fridman (21:15.660)
and there's a huge space of possibilities
Lex Fridman (21:17.340)
of things that can exist.
Lex Fridman (21:18.500)
And when I say information and causation,
Lex Fridman (21:20.540)
what I mean is why is it that cups evolved in the universe
Lex Fridman (21:24.900)
and not some other object that could deliver water
Lex Fridman (21:27.540)
and not spill it?
Sara Walker (21:29.740)
I don't know what you would call it.
Lex Fridman (21:31.580)
Maybe it wouldn't be a cup, but it's a huge,
Sara Walker (21:37.060)
people talk about the space of things that could exist
Lex Fridman (21:38.980)
as being actually infinitely large, right?
Sara Walker (21:40.860)
I don't know if I believe in infinity,
Lex Fridman (21:43.420)
but I do think that there is something very interesting
Sara Walker (21:47.380)
about the problem of what exists
Lex Fridman (21:51.980)
in its relationship to life.
Lex Fridman (21:53.300)
So do you think the set of things
Lex Fridman (21:55.700)
that could exist is finite?
Sara Walker (21:58.020)
It's very large, but if we were to think
Lex Fridman (22:00.700)
about the physics of existence,
Lex Fridman (22:04.260)
how many shapes of mugs can there be?
Lex Fridman (22:08.420)
In the initial programming.
Sara Walker (22:10.060)
I should go to the math department for that.
Lex Fridman (22:13.020)
So that's not a topology question.
Sara Walker (22:14.700)
I just mean, maybe another way to ask is
Lex Fridman (22:17.780)
what do you think is fundamental to the universe
Lex Fridman (22:20.340)
and what is emergent?
Lex Fridman (22:21.660)
So if existence, are we supposed to think of that
Lex Fridman (22:24.800)
as somehow fundamental, you think?
Lex Fridman (22:26.900)
So there's a couple of problems in physics
Sara Walker (22:28.660)
that I think this is related to.
Lex Fridman (22:29.820)
One is why does mathematics work
Lex Fridman (22:31.380)
at describing reality so well?
Lex Fridman (22:33.300)
And then there is this problem of we don't understand
Lex Fridman (22:36.500)
why the laws of physics are the way they are,
Lex Fridman (22:38.800)
or why certain things get to exist,
Sara Walker (22:40.660)
or what put in place the initial condition of our universe.
Lex Fridman (22:44.060)
There's all of these sort of really deep and big problems,
Lex Fridman (22:47.440)
and they all indirectly are related, I think,
Lex Fridman (22:51.900)
to the same kind of thing that,
Sara Walker (22:55.420)
our physics is really good
Lex Fridman (22:56.860)
if you specify the initial condition
Sara Walker (22:58.620)
at specifying a certain sequence of events,
Lex Fridman (23:01.000)
but it doesn't deal with the fact
Sara Walker (23:03.180)
that other things could have happened,
Lex Fridman (23:04.980)
which is kind of an informational property,
Sara Walker (23:06.640)
like a counterfactual property.
Lex Fridman (23:08.820)
And it's not good at explaining
Sara Walker (23:13.780)
this conversation right now.
Lex Fridman (23:15.860)
There are certain things that are outside
Sara Walker (23:17.660)
the explanatory reach of current physics,
Lex Fridman (23:19.620)
and I think they require looking at it
Sara Walker (23:22.900)
from a completely different direction.
Lex Fridman (23:25.060)
And so I don't wanna have to fine tune
Sara Walker (23:26.980)
the initial condition of the universe
Lex Fridman (23:28.860)
to specify precisely all the information
Sara Walker (23:30.740)
in this conversation.
Lex Fridman (23:31.580)
I think that's a ridiculous assertion.
Lex Fridman (23:33.620)
But that's sort of like how people wanna frame it
Lex Fridman (23:35.620)
when they talk about the standard model is sufficient
Sara Walker (23:40.580)
if we had computing power
Lex Fridman (23:42.060)
to basically explain all of life in our existence.
Sara Walker (23:44.660)
An interesting thing you said
Lex Fridman (23:45.780)
is the way we think about information computation
Sara Walker (23:48.640)
is by observing a particular kind of systems on Earth
Lex Fridman (23:53.380)
that exhibit something we think of as intelligence.
Lex Fridman (23:56.860)
But that's like looking at, I guess, the tip of an iceberg,
Lex Fridman (24:01.060)
and we should be really looking at the fundamentals
Sara Walker (24:03.060)
of the iceberg, like what makes water and ice
Lex Fridman (24:08.900)
and the chemistry from which intelligence emerges,
Sara Walker (24:13.100)
essentially. Yes, yes.
Lex Fridman (24:14.680)
We can't just couple the information from the physics,
Lex Fridman (24:17.140)
and I think that's what we've gotten really good at doing,
Lex Fridman (24:19.300)
especially with sort of the modern age
Sara Walker (24:23.540)
where software is so abstracted from hardware.
Lex Fridman (24:29.580)
But the entire process of biological evolution
Sara Walker (24:31.780)
has basically been built,
Lex Fridman (24:33.300)
like been building layers of increasing abstraction.
Lex Fridman (24:36.700)
And so it's really hard to see that physics in us,
Lex Fridman (24:39.300)
but it's much clearer to see it in molecules.
Sara Walker (24:42.540)
Yeah, but I guess I'm trying to figure out
Lex Fridman (24:44.820)
what do you think are the best tools to look at it?
Lex Fridman (24:48.580)
What do you think?
Lex Fridman (24:50.340)
An open mind?
Lex Fridman (24:51.660)
Is that a tool?
Lex Fridman (24:53.460)
What's the physics of an open mind?
Sara Walker (24:56.620)
I think if we solve that, we'll solve everything.
Lex Fridman (24:58.580)
I'm saying an open mind
Sara Walker (24:59.660)
because I think the biggest stumbling block
Lex Fridman (25:03.700)
to understanding sort of the things
Sara Walker (25:05.940)
I've been trying to articulate,
Lex Fridman (25:07.660)
and when I talk also with colleagues
Sara Walker (25:09.020)
that are thinking deeply about these same issues,
Lex Fridman (25:11.660)
is none of it is inconsistent with what we know.
Sara Walker (25:15.440)
It's just such a radically different perception
Lex Fridman (25:18.260)
of the way we understand things now
Sara Walker (25:19.700)
that it's hard for people to get there.
Lex Fridman (25:21.340)
And in some ways you have to almost forget
Lex Fridman (25:23.140)
what you've learned in order to learn something new, right?
Lex Fridman (25:25.900)
So I feel like most of my career
Sara Walker (25:27.900)
trying to understand the problem of life
Lex Fridman (25:29.920)
has been variously forgetting
Lex Fridman (25:32.460)
and then relearning things that I learned in physics.
Lex Fridman (25:35.620)
And I think you have to have a capacity to learn things,
Lex Fridman (25:41.800)
but then accept that things that you learned
Lex Fridman (25:44.460)
might not be true or might need refinement or reframing.
Lex Fridman (25:51.900)
And the best way I can say that
Lex Fridman (25:53.300)
is just like with a physics education,
Sara Walker (25:54.660)
there are just certain things you're told in undergrad
Lex Fridman (25:56.900)
that are like facts about the world.
Lex Fridman (25:58.980)
And your physics professors never tell you
Lex Fridman (26:01.300)
that those facts actually emerge from a human mind, right?
Lex Fridman (26:04.300)
So we're taught to think about,
Lex Fridman (26:05.500)
say the laws of physics, for example,
Sara Walker (26:07.420)
as this like autonomous thing
Lex Fridman (26:09.460)
that exists outside of our universe
Lex Fridman (26:10.800)
and tells our universe how it works.
Lex Fridman (26:13.500)
But the laws of physics were invented by human minds
Sara Walker (26:15.500)
to describe things that are regularities
Lex Fridman (26:17.460)
in our everyday experience.
Sara Walker (26:19.420)
They don't exist autonomous to the universe.
Lex Fridman (26:21.620)
Right, so it's like turtles on top of turtles,
Lex Fridman (26:23.940)
but eventually it gets to the human mind,
Lex Fridman (26:26.420)
and then you have to explain the human mind with the turtles.
Lex Fridman (26:29.740)
So you have to, it comes from humans,
Lex Fridman (26:32.620)
this understanding, this simplification of the universe,
Sara Walker (26:34.740)
these models.
Lex Fridman (26:36.340)
There's a guy named Stephen Wolfram.
Sara Walker (26:38.260)
There's a concept called cellular automata.
Lex Fridman (26:42.020)
So there's some mysteries in these systems
Sara Walker (26:47.580)
that are computational in nature
Lex Fridman (26:49.420)
that have maybe echoes of the kind of mysteries
Sara Walker (26:54.020)
we should need to solve to understand what is life.
Lex Fridman (26:59.060)
So if we could talk, take a computational view of things,
Lex Fridman (27:04.620)
do you think there's something compelling
Lex Fridman (27:06.220)
to reducing everything down to computation,
Sara Walker (27:09.860)
like the universe is computation,
Lex Fridman (27:12.060)
and then trying to understand life?
Lex Fridman (27:15.260)
So throw away the biology, throw away the chemistry,
Lex Fridman (27:18.900)
throw away even the physics
Sara Walker (27:20.100)
that you learn undergrad and graduate school,
Lex Fridman (27:22.780)
and more look at these simple little systems,
Sara Walker (27:25.940)
whether it's cellular automata or whatever the heck
Lex Fridman (27:28.340)
kind of computational systems
Sara Walker (27:29.660)
that operate on simple local rules
Lex Fridman (27:31.540)
and then create complexity as they evolve.
Sara Walker (27:36.220)
Is it at all, do you think, productive
Lex Fridman (27:39.460)
to focus on those kinds of systems
Lex Fridman (27:42.100)
to get an inkling of what is life?
Lex Fridman (27:44.220)
And if it is, do you think it's possible
Sara Walker (27:48.740)
to come up with some kind of laws and principles
Lex Fridman (27:51.620)
about what makes life in those computational systems?
Lex Fridman (27:56.140)
So I like cellular automata.
Lex Fridman (27:57.460)
I think they're good toy models,
Lex Fridman (27:59.580)
but mostly where I've thought about them and used them
Lex Fridman (28:02.620)
is to actually, let's say,
Sara Walker (28:07.420)
poke at sort of the current conceptual framework
Lex Fridman (28:10.380)
that we have and see where the flaws are.
Lex Fridman (28:13.180)
So I think the part that you're talking about
Lex Fridman (28:15.660)
that people find intriguing is that
Sara Walker (28:17.260)
if you have a fairly simple rule
Lex Fridman (28:19.660)
and you specify some initial condition
Lex Fridman (28:21.580)
and you run that rule on that initial condition,
Lex Fridman (28:23.460)
you could get really complex patterns emerging.
Lex Fridman (28:26.460)
And ooh, doesn't that look lifelike?
Lex Fridman (28:28.980)
Yeah.
Sara Walker (28:29.820)
Yeah.
Lex Fridman (28:31.140)
Well, it's like really surprising,
Lex Fridman (28:32.220)
isn't it really surprising?
Lex Fridman (28:33.060)
It is really surprising, and they're beautiful.
Lex Fridman (28:35.180)
And I think they have a lot of nice features
Lex Fridman (28:37.740)
associated to them.
Sara Walker (28:39.660)
I think the things that I find,
Lex Fridman (28:42.260)
yeah, so I do think as a proof of principle
Sara Walker (28:46.420)
that you can get complex things emerging from simple rules.
Lex Fridman (28:49.020)
They're great.
Sara Walker (28:50.420)
As a sort of proof of principle about some of the ways
Lex Fridman (28:53.660)
that we might think of computation
Sara Walker (28:56.700)
as being sort of a fundamental principle
Lex Fridman (28:59.380)
for dynamical systems
Lex Fridman (29:00.700)
and maybe the evolution of the universe as a whole,
Lex Fridman (29:03.220)
they're a great model system.
Sara Walker (29:05.620)
As an explanatory framework for life,
Lex Fridman (29:07.820)
I think they're a bit problematic
Sara Walker (29:10.860)
for the same reason that the laws of physics
Lex Fridman (29:14.060)
are a bit problematic.
Lex Fridman (29:16.260)
And the clearest way I can articulate that
Lex Fridman (29:19.260)
is like cellular automata are actually cast
Sara Walker (29:22.380)
in sort of a conceptual framework
Lex Fridman (29:24.820)
for how the universe should be described
Sara Walker (29:26.500)
that goes all the way back to Newton, in fact,
Lex Fridman (29:29.580)
with this idea that we can have a fixed law of motion,
Sara Walker (29:33.660)
which exists sort of, it's given to you.
Lex Fridman (29:37.420)
The great programmer in the sky gave you this equation
Sara Walker (29:40.420)
or this rule, and then you just run with it.
Lex Fridman (29:43.340)
And the rule doesn't have,
Lex Fridman (29:45.020)
so a good feature of the rule
Lex Fridman (29:46.540)
is it doesn't have specified in the rule
Sara Walker (29:49.140)
information about the patterns it generates.
Lex Fridman (29:51.020)
So you wouldn't want, for example,
Sara Walker (29:53.780)
my cup or my water bottle or me sitting here
Lex Fridman (29:56.940)
to be specified in the laws of physics.
Sara Walker (29:58.580)
That would be ridiculous
Lex Fridman (29:59.420)
because it wouldn't be a very simple explanation
Sara Walker (30:01.140)
of all the things happening.
Lex Fridman (30:01.980)
It'd have to explain everything.
Sara Walker (30:03.540)
So, and cellular automata have that feature
Lex Fridman (30:06.100)
and the laws of physics have that feature.
Lex Fridman (30:09.300)
But you also need to specify the initial condition.
Lex Fridman (30:13.060)
And it also, it basically means
Sara Walker (30:15.380)
that everything that happens
Lex Fridman (30:17.020)
is sort of a consequence of that initial condition.
Lex Fridman (30:19.860)
And I think this kind of framework
Lex Fridman (30:21.740)
is just not the right one for biology.
Lex Fridman (30:25.020)
And part of the way that it's easiest to see this
Lex Fridman (30:28.220)
is a lot of people talk about self reference
Sara Walker (30:31.820)
being important in life.
Lex Fridman (30:33.420)
The fact that, you know,
Sara Walker (30:35.300)
like the genome has information encoded in it,
Lex Fridman (30:39.220)
that information gets read out.
Sara Walker (30:41.660)
It specifies something about the architecture of a cell.
Lex Fridman (30:45.100)
The architecture of the cell includes the genome.
Lex Fridman (30:47.020)
So the genome has basically self referential information.
Lex Fridman (30:49.780)
Self reference obviously comes up in computational law
Sara Walker (30:52.980)
because it's kind of foundational to Turing's work
Lex Fridman (30:56.660)
and what Gödel did with the incompleteness theorems
Lex Fridman (30:58.900)
and things.
Lex Fridman (30:59.740)
So there's a lot of parallels there
Lex Fridman (31:02.540)
and people have talked about that at depth.
Lex Fridman (31:05.380)
But the other way of kind of thinking about it
Sara Walker (31:06.780)
in terms of like a more physicsy way of talking about it
Lex Fridman (31:10.060)
is that what it looks like in biology
Sara Walker (31:12.220)
is that the rules or the laws depend on the state.
Lex Fridman (31:15.860)
This is typical in computer science.
Sara Walker (31:17.260)
This is obvious to you.
Lex Fridman (31:18.460)
You know, the update rule depends
Lex Fridman (31:19.780)
on the state of the machine, right?
Lex Fridman (31:20.900)
But, you know, you don't think about, you know,
Sara Walker (31:24.740)
that being sort of the dynamic in physics.
Lex Fridman (31:27.500)
It's, you know, the rules given to you
Lex Fridman (31:28.900)
and then it's a very special subclass say of computations
Lex Fridman (31:32.660)
if, you know, you don't ever change the update.
Lex Fridman (31:36.540)
But in biology, it seems to be that the state
Lex Fridman (31:38.300)
and the law change together as a function of time
Lex Fridman (31:40.980)
and we don't have that as a paradigm in physics.
Lex Fridman (31:43.740)
And so a lot of people talk about this
Sara Walker (31:45.620)
as being kind of a perplexing feature
Lex Fridman (31:47.540)
that maybe there are certain scenarios
Sara Walker (31:49.740)
where the laws of physics
Lex Fridman (31:51.140)
or the laws that govern a particular system
Sara Walker (31:52.980)
actually change as a function of the state of that system.
Lex Fridman (31:56.580)
That's trippy.
Sara Walker (31:57.420)
Yeah.
Lex Fridman (31:58.260)
So yeah, the hope of physics, it's a hope, I guess,
Lex Fridman (32:01.660)
but often stated as a underlying assumption
Lex Fridman (32:05.340)
is that the law is static.
Sara Walker (32:08.740)
Right.
Lex Fridman (32:10.100)
Okay.
Lex Fridman (32:10.940)
And even having laws that vary in time
Lex Fridman (32:12.580)
and not even as a function of the state is very radical.
Sara Walker (32:16.220)
When you...
Lex Fridman (32:17.060)
The time in general, like you wanna remove time
Sara Walker (32:20.020)
from the equation as much as possible.
Lex Fridman (32:22.020)
Yeah, I do.
Sara Walker (32:24.220)
There's some interesting things in this
Lex Fridman (32:25.580)
like when we think sort of more deeply
Sara Walker (32:28.020)
about the actual physics that we're trying to propose
Lex Fridman (32:29.980)
governs life with me with collaborators
Lex Fridman (32:32.660)
and then also other people that think about similar things
Lex Fridman (32:35.160)
that time might actually be fundamental
Lex Fridman (32:36.760)
and there really is an ordering to time.
Lex Fridman (32:38.900)
And that events in the universe are unique
Sara Walker (32:41.020)
because they have a particular, they happen,
Lex Fridman (32:43.980)
like an object in the universe
Sara Walker (32:45.180)
requires a certain history of events in order to exist,
Lex Fridman (32:48.300)
which therefore suggests
Sara Walker (32:49.300)
that time really does have an ordering.
Lex Fridman (32:50.580)
I'm not talking about the flow of time
Lex Fridman (32:51.420)
and our perception of time, just the ordering of events.
Lex Fridman (32:53.660)
Causation of things.
Sara Walker (32:54.500)
Yes, causation, there's that word again.
Lex Fridman (32:56.660)
So causation, that's when you say time, you mean causation.
Sara Walker (32:59.460)
Yes.
Lex Fridman (33:00.780)
In your proposed model of the physics of life,
Sara Walker (33:05.820)
the fundamental thing would be causation.
Lex Fridman (33:08.300)
If you were to bet your money
Sara Walker (33:09.740)
on one particular horse or whatever.
Lex Fridman (33:12.440)
Yes.
Lex Fridman (33:13.280)
And then space is emergent.
Lex Fridman (33:15.480)
Yes.
Lex Fridman (33:16.320)
So everything's emergent except time.
Lex Fridman (33:19.140)
Kind of, yeah, or causation.
Lex Fridman (33:21.060)
And laws change all the time.
Lex Fridman (33:22.700)
Why does it look like laws are the same?
Sara Walker (33:24.260)
Laws, well, because, well, one way,
Lex Fridman (33:27.940)
and I actually, this idea comes from Lee Cronin
Sara Walker (33:29.980)
because I work with him very closely on these things,
Lex Fridman (33:31.860)
is that the laws of physics look the way they do
Sara Walker (33:33.780)
because they're low memory laws.
Lex Fridman (33:35.580)
So they don't require a lot of information to specify them.
Sara Walker (33:37.860)
They're very easy for the universe to implement.
Lex Fridman (33:39.740)
But if you get something like me, for example,
Sara Walker (33:42.100)
I require 4 billion year history to exist in the universe.
Lex Fridman (33:44.560)
I come with a lot of historical baggage.
Lex Fridman (33:47.100)
And that's part of what I am
Lex Fridman (33:48.400)
as a set of causes that exist in the universe.
Lex Fridman (33:52.680)
So I have local rules that apply to me
Lex Fridman (33:55.220)
that are associated with sort of the information
Sara Walker (33:57.020)
in my history that aren't universal
Lex Fridman (33:59.220)
to every object in the universe.
Lex Fridman (34:01.020)
And there are some things that are very easy
Lex Fridman (34:03.820)
to implement low memory rules
Sara Walker (34:06.020)
that apply to everything in the universe.
Lex Fridman (34:08.780)
So there's no shortcuts to you.
Sara Walker (34:10.540)
No, so yeah, I don't believe in things like Boltzmann brains
Lex Fridman (34:13.580)
or fluctuations out of the vacuum
Sara Walker (34:17.260)
that can produce things like your desk ornaments.
Lex Fridman (34:21.420)
I actually think they require
Sara Walker (34:23.380)
a particular causal chain of events to exist.
Lex Fridman (34:26.460)
Well, I appreciate the togetherness of that,
Lex Fridman (34:28.580)
but so how does that,
Lex Fridman (34:31.020)
if we have to simulate the entire universe
Sara Walker (34:34.020)
to create the ornaments in the two of us,
Lex Fridman (34:37.060)
how are we supposed to create engineer life in the lab?
Sara Walker (34:42.860)
This goes back to sort of the critique of the RNA world.
Lex Fridman (34:45.440)
I think one of the problems,
Lex Fridman (34:46.940)
and I'll get to answer your question,
Lex Fridman (34:48.340)
but I think this is kind of relevant here.
Sara Walker (34:50.300)
One of the problems with the RNA world,
Lex Fridman (34:52.820)
when we test it in the laboratory,
Sara Walker (34:54.260)
is how much information we're putting into the experiment.
Lex Fridman (34:57.300)
We specify the flasks, we make pure reagents,
Sara Walker (35:00.060)
we mix them, we take them out,
Lex Fridman (35:01.860)
we put them in the next flask,
Sara Walker (35:03.420)
we change the pH, we change the UV light,
Lex Fridman (35:05.620)
and then we get a molecule,
Lex Fridman (35:07.100)
and it's not even an RNA molecule necessarily,
Lex Fridman (35:09.060)
it might just be a base, right?
Lex Fridman (35:11.140)
And so people don't usually think about the fact
Lex Fridman (35:14.680)
that we're agents in the universe making that experiment,
Lex Fridman (35:17.860)
and therefore we put a little bit of life
Lex Fridman (35:19.460)
into that experiment,
Sara Walker (35:21.860)
because it's part of our biological lineage,
Lex Fridman (35:23.740)
in the same sense that I am a part of the biological lineage.
Sara Walker (35:26.820)
The experiment is.
Lex Fridman (35:27.660)
I mean, our ideas are injecting life.
Sara Walker (35:31.140)
Yes.
Lex Fridman (35:31.980)
And the constraints that we put on the experiments,
Sara Walker (35:34.140)
because those conditions wouldn't exist in the universe
Lex Fridman (35:36.740)
on planet Earth at that time
Lex Fridman (35:38.580)
without us as the boundary condition, right?
Lex Fridman (35:40.420)
So.
Sara Walker (35:41.420)
Even though we're not actually adding
Lex Fridman (35:42.780)
any actual chemistry or biology
Sara Walker (35:45.160)
that could be identified as life,
Lex Fridman (35:47.660)
are the constraints we're adding to the experiment,
Sara Walker (35:49.860)
the design of the experiment.
Lex Fridman (35:51.300)
Yeah, you can think of the design experiment as a program.
Sara Walker (35:53.080)
You put information in.
Lex Fridman (35:54.340)
It's an algorithmic procedure that you design the experiment.
Lex Fridman (35:57.180)
And so the origin of life problem
Lex Fridman (35:59.940)
becomes one of minimizing the information
Sara Walker (36:02.740)
we put into physics
Lex Fridman (36:04.900)
to actually watch the spontaneous origin of life.
Sara Walker (36:07.140)
Can we have, so can, is it possible in the lab
Lex Fridman (36:09.860)
to have an information vacuum then?
Lex Fridman (36:12.180)
So like.
Lex Fridman (36:13.020)
If we could, we would, that would be amazing.
Sara Walker (36:14.980)
I don't know.
Lex Fridman (36:15.820)
That's a good question for, more for Lee.
Sara Walker (36:17.700)
Yeah, you guys, by the way,
Lex Fridman (36:18.700)
for people who don't know, Lee Cronin is,
Sara Walker (36:21.260)
you guys are colleagues.
Lex Fridman (36:23.020)
Yeah.
Sara Walker (36:23.860)
I've gotten the chance to listen to the two of you talking.
Lex Fridman (36:26.980)
There's great sort of chemistry
Lex Fridman (36:28.300)
and you're brilliant brainstorming together.
Lex Fridman (36:30.580)
And there's a really exciting community here
Sara Walker (36:34.420)
of brilliant people from different disciplines
Lex Fridman (36:36.900)
working on the problem of life, of complexity,
Sara Walker (36:39.820)
of, I don't know, whatever.
Lex Fridman (36:42.420)
The words fail us to describe the exact problem
Sara Walker (36:45.220)
we're trying to actually understand here.
Lex Fridman (36:47.340)
Intelligence, all those kinds of things.
Sara Walker (36:49.300)
Okay, so what, from a lab perspective,
Lex Fridman (36:54.660)
so Lee, I guess, would you call him a chemist?
Lex Fridman (36:57.260)
No?
Lex Fridman (36:58.100)
I think by training he's a chemist,
Lex Fridman (36:59.580)
but I think most of the people that work in the field,
Lex Fridman (37:01.140)
we do have lost their discipline.
Sara Walker (37:02.700)
That's why I couldn't answer your question earlier.
Lex Fridman (37:06.260)
Okay.
Sara Walker (37:07.100)
I don't know what you call him.
Lex Fridman (37:07.940)
Yeah.
Sara Walker (37:08.780)
I don't know what I call myself.
Lex Fridman (37:09.620)
I don't know what I call any of my friends.
Lex Fridman (37:11.300)
So why is it so hard to create,
Lex Fridman (37:15.140)
and it's an interesting question,
Sara Walker (37:16.380)
to create biological life in the lab.
Lex Fridman (37:19.380)
Like from your perspective,
Sara Walker (37:21.780)
is that an important problem to work on
Lex Fridman (37:23.980)
to try to recreate the historical origin of life on Earth
Lex Fridman (37:29.180)
or echoes of the historical origin?
Lex Fridman (37:31.100)
I think echoes is more appropriate.
Sara Walker (37:32.740)
I don't think asking the question
Lex Fridman (37:34.900)
of what was the exact historical sequence of events
Lex Fridman (37:37.660)
and engineering every step in the process
Lex Fridman (37:40.420)
to make exactly the chemistry of life on Earth as we know it
Sara Walker (37:44.060)
is a meaningful way of asking the question.
Lex Fridman (37:46.340)
And it's a little bit like,
Sara Walker (37:49.660)
since you're in computer science,
Lex Fridman (37:50.980)
like if you know the answer to a problem,
Lex Fridman (37:53.420)
it's easier to find a program to specify the output, right?
Lex Fridman (37:56.020)
But if you don't know the answer a priori,
Sara Walker (37:58.340)
finding an algorithm for it,
Lex Fridman (37:59.740)
like say finding a prime or something,
Sara Walker (38:01.020)
it's easy to verify it's a prime number.
Lex Fridman (38:04.980)
It's hard to find the next prime.
Lex Fridman (38:07.500)
And the way the origin of life is structured right now
Lex Fridman (38:10.940)
in the historical problem is you know the answer
Lex Fridman (38:14.260)
and you're trying to retrodict it by breaking it down
Lex Fridman (38:16.460)
into the set of procedures
Sara Walker (38:17.580)
where you're putting a lot of information in.
Lex Fridman (38:19.420)
And what we need to do is ask the question
Sara Walker (38:21.700)
of how is it that the rules of how our universe is structured
Lex Fridman (38:26.140)
permit things like life to exist
Lex Fridman (38:28.060)
and what is the phenomena of life?
Lex Fridman (38:29.740)
And those questions are obviously
Sara Walker (38:31.380)
essentially the same question.
Lex Fridman (38:33.060)
And so you're looking essentially for this missing physics,
Sara Walker (38:37.820)
this missing explanation for what we are,
Lex Fridman (38:39.700)
and you need to set up proper experiments
Sara Walker (38:41.700)
that are gonna allow you to probe
Lex Fridman (38:43.500)
the vast complexity of chemistry in an unconstrained way
Sara Walker (38:47.420)
with as little information put in as possible
Lex Fridman (38:50.180)
to see when things, when does information actually emerge?
Lex Fridman (38:53.900)
How does it emerge?
Lex Fridman (38:55.300)
What is it?
Lex Fridman (38:57.260)
And part of the sort of conjecture we have
Lex Fridman (39:00.260)
is that this physics only becomes relevant
Sara Walker (39:03.140)
or at least this is my personal conjecture
Lex Fridman (39:05.780)
and it's sort of validated
Sara Walker (39:08.500)
by this kind of theory experiment collaboration
Lex Fridman (39:10.780)
that we have working in this area that this, you know,
Sara Walker (39:15.300)
sort of, I made the point about like gravity
Lex Fridman (39:17.420)
existing everywhere, right?
Lex Fridman (39:18.580)
But when you study an atomic nucleus,
Lex Fridman (39:21.260)
you don't care about gravity.
Lex Fridman (39:22.340)
It's not relevant physics there, right?
Lex Fridman (39:23.980)
It's weak, it doesn't matter.
Lex Fridman (39:26.020)
And so this idea that there's kind of a physics
Lex Fridman (39:30.620)
associated with information,
Sara Walker (39:32.780)
for me, it's very evident that that physics
Lex Fridman (39:36.260)
doesn't become relevant until you need information
Sara Walker (39:38.940)
to specify the existence of a particular object.
Lex Fridman (39:41.620)
And the scale of reality where that happens
Sara Walker (39:44.140)
is in chemistry because of the combinatorial diversity
Lex Fridman (39:47.620)
of chemical objects that can exist far out,
Sara Walker (39:50.980)
exceeds the amount of resources in our universe.
Lex Fridman (39:53.740)
So if you want it, you can't make every possible protein
Sara Walker (39:56.620)
of length, you know, 200 amino acids,
Lex Fridman (39:59.460)
there's not enough resources.
Lex Fridman (40:00.900)
So in order for this particular protein to exist
Lex Fridman (40:04.100)
and this protein to exist in high abundance
Sara Walker (40:06.660)
means that you have to have a system that has knowledge
Lex Fridman (40:10.140)
of the existence of that protein and can build it.
Lex Fridman (40:12.900)
So existence comes to be at the chemical level.
Lex Fridman (40:15.580)
So existence is most, is best understood
Sara Walker (40:19.660)
at the chemical level.
Lex Fridman (40:20.700)
It's most evident.
Sara Walker (40:22.060)
It's a little bit like, nobody argues that gravity
Lex Fridman (40:24.260)
doesn't exist in an atomic nucleus.
Lex Fridman (40:25.820)
It's just not relevant physics there, right?
Lex Fridman (40:27.820)
So the physics of information.
Sara Walker (40:29.860)
Is everywhere.
Lex Fridman (40:30.700)
It exists at every combinatorial scale,
Lex Fridman (40:32.500)
but it becomes more and more relevant
Lex Fridman (40:34.180)
the more set of possibilities that could exist
Sara Walker (40:36.740)
because you have to specify more and more
Lex Fridman (40:39.340)
about why this thing exists and not the infinite.
Sara Walker (40:41.780)
It's not an infinite set, but you know,
Lex Fridman (40:43.340)
the set of undefined set of other things that could exist.
Lex Fridman (40:46.140)
So can I ask a weird question, which is,
Lex Fridman (40:50.540)
so let's look into the future.
Sara Walker (40:53.580)
I try that every day.
Lex Fridman (40:54.420)
It never works.
Lex Fridman (40:56.180)
So say a Nobel prize is given in physics,
Lex Fridman (41:00.100)
maybe chemistry for discovering the origin of life.
Sara Walker (41:06.540)
No, but not the historical origin.
Lex Fridman (41:09.140)
Some kind of thing that we're talking about.
Lex Fridman (41:12.620)
What exactly would, what do you think that,
Lex Fridman (41:19.900)
like, what do you think that person,
Lex Fridman (41:22.460)
maybe you did to get that Nobel prize?
Lex Fridman (41:24.700)
Like what would they have to have done?
Sara Walker (41:26.220)
Cause you can do a bunch of experiments that go
Lex Fridman (41:28.380)
like within the aha moment.
Sara Walker (41:30.620)
Like you rarely get the Nobel prize for like,
Lex Fridman (41:34.540)
you've solved everything, we're done.
Sara Walker (41:37.060)
It's like some inkling of some deep truth.
Lex Fridman (41:40.900)
Like what do you think that would actually look like?
Lex Fridman (41:43.220)
Would it be an experimental result?
Lex Fridman (41:46.380)
I mean, it will have to have some kind of experimental,
Sara Walker (41:48.820)
maybe validation component.
Lex Fridman (41:50.300)
So what would that look like?
Sara Walker (41:52.260)
This is an excellent question.
Lex Fridman (41:54.620)
I want to, sorry, I'm going to make a quick point,
Sara Walker (41:57.220)
which is just a slight tangent.
Lex Fridman (41:58.700)
But you know, like when people ask about the origin of mass,
Lex Fridman (42:01.220)
and like looking for the Higgs mechanism and things,
Lex Fridman (42:03.260)
they never are like,
Sara Walker (42:04.220)
we need to find the historical origins of life
Lex Fridman (42:06.300)
in the early unit.
Lex Fridman (42:07.140)
Although those things are related, right?
Lex Fridman (42:08.380)
So this problem of origins of life in the lab,
Sara Walker (42:11.420)
I think is really important.
Lex Fridman (42:12.580)
But the Higgs is a good example
Sara Walker (42:14.500)
because you had theory to guide it.
Lex Fridman (42:15.940)
So somehow you need to have an explanatory framework
Sara Walker (42:20.420)
that can say that we should be looking for these features
Lex Fridman (42:24.700)
and explain why they might be there
Lex Fridman (42:27.300)
and then be able to do the experiment
Lex Fridman (42:28.980)
and demonstrate that it matches with the theory.
Lex Fridman (42:30.980)
But it has to be something that is outside
Lex Fridman (42:33.740)
sort of the paradigm of what we might expect
Lex Fridman (42:35.740)
based on what we know, right?
Lex Fridman (42:36.940)
So this is a really sort of tall order.
Lex Fridman (42:39.860)
And I think, I mean, I guess the way people would think
Lex Fridman (42:45.540)
about it is like, you know,
Sara Walker (42:46.380)
if you had a bacteria that climbed out of your test tube
Lex Fridman (42:48.780)
or something, and it was like, you know,
Sara Walker (42:49.980)
moving around on the surface,
Lex Fridman (42:51.100)
that would be ultimate validation.
Sara Walker (42:52.460)
You saw the origin of life in an experiment,
Lex Fridman (42:54.580)
but I don't think that's quite what we're looking for.
Sara Walker (42:56.900)
I think what we're looking for is evidence
Lex Fridman (43:01.420)
of when information that originated
Sara Walker (43:05.500)
within the bounds of your experiment
Lex Fridman (43:07.900)
and you can demonstrably prove emerged spontaneously
Sara Walker (43:11.460)
in your experiment, wasn't put in by you,
Lex Fridman (43:14.100)
actually started to govern the future dynamics
Sara Walker (43:17.260)
of that system and specify it.
Lex Fridman (43:19.620)
And you could somehow relate those two features directly.
Lex Fridman (43:23.540)
So you know that the program specifying
Lex Fridman (43:26.260)
what's happening in that system
Sara Walker (43:27.540)
is actually internal to that system.
Lex Fridman (43:29.700)
Like say you have a chemical thing in a box.
Sara Walker (43:32.100)
Well, so that's one Nobel Prize winning experiment,
Lex Fridman (43:36.340)
which is like information in some fundamental way
Sara Walker (43:39.920)
originated within the constraints of the system
Lex Fridman (43:42.860)
without you injecting anything.
Lex Fridman (43:44.600)
But another experiment is you injected something.
Lex Fridman (43:49.180)
Yeah.
Lex Fridman (43:50.100)
And got out information.
Lex Fridman (43:52.100)
Yes.
Lex Fridman (43:52.940)
So like you injected, I don't know,
Lex Fridman (43:55.740)
like some sugar and like something that doesn't necessarily
Sara Walker (44:01.260)
feel like it should be information.
Lex Fridman (44:03.420)
Yeah, so I actually know, I mean,
Lex Fridman (44:05.940)
sugar is information, right?
Lex Fridman (44:07.140)
So part of the argument here is that every physical object
Sara Walker (44:10.120)
is, well, it's information,
Lex Fridman (44:12.880)
but it's a set of causal histories
Lex Fridman (44:14.580)
and also a set of possible futures.
Lex Fridman (44:16.620)
So there is an experiment that I've talked a lot about
Sara Walker (44:20.500)
with Lee Cronin, but also with Michael Lockman
Lex Fridman (44:22.100)
and Chris Kempis who are at Santa Fe
Sara Walker (44:23.900)
about this idea that sometimes we talk about
Lex Fridman (44:25.780)
as like seeding assembly,
Sara Walker (44:27.900)
which is you take a high complexity,
Lex Fridman (44:30.560)
like an object that exists in the universe
Sara Walker (44:32.860)
because of a long causal history,
Lex Fridman (44:34.900)
and you seed it into a system of lower causal history.
Lex Fridman (44:38.500)
And then suddenly you see all of this complexity
Lex Fridman (44:40.860)
being generated.
Lex Fridman (44:41.980)
So I think another validation of the physics would be,
Lex Fridman (44:44.980)
say you engineer an organism
Sara Walker (44:46.940)
by purposefully introducing something
Lex Fridman (44:49.740)
where you understand the relationship
Sara Walker (44:51.220)
between the causal history of the organism
Lex Fridman (44:54.080)
and the say very complex chemical set of ingredients
Sara Walker (44:57.580)
you're adding to it.
Lex Fridman (44:58.820)
And then you can predict the future evolution of that system
Sara Walker (45:01.980)
to some statistical set of constraints and possibilities
Lex Fridman (45:06.920)
for what it will look like in the future.
Sara Walker (45:11.620)
I'm a physical structure, obviously,
Lex Fridman (45:12.900)
like I'm composed of atoms,
Sara Walker (45:15.220)
the configuration of them
Lex Fridman (45:16.660)
and the fact that they happen to be me
Sara Walker (45:19.380)
is because I'm not actually my atoms,
Lex Fridman (45:22.060)
I am a informational pattern
Sara Walker (45:24.680)
that keeps re patterning those atoms into Sarah.
Lex Fridman (45:28.940)
And I have also associated to me
Sara Walker (45:32.060)
like a space of possible things that could exist
Lex Fridman (45:36.220)
that I can help mediate come into existence
Sara Walker (45:38.200)
because of the information in my history.
Lex Fridman (45:41.240)
And so when you understand sort of that
Sara Walker (45:45.720)
time is a real thing embedded in a physical object,
Lex Fridman (45:50.080)
then it becomes possible to talk about
Lex Fridman (45:52.920)
how histories when they interact
Lex Fridman (45:56.960)
and a history is not a unique thing,
Sara Walker (45:58.420)
it's a set of possibilities.
Lex Fridman (45:59.900)
When they interact,
Lex Fridman (46:00.740)
how do they specify what's coming next?
Lex Fridman (46:03.200)
And then where does the novelty come from in that structure?
Sara Walker (46:05.280)
Cause some of it is kind of things
Lex Fridman (46:06.600)
that haven't existed in the past can exist in the future.
Sara Walker (46:09.940)
Let me ask about this entity that you call Sarah.
Lex Fridman (46:12.800)
Yes.
Sara Walker (46:14.120)
I talk to myself about myself in third person sometimes.
Lex Fridman (46:16.840)
I don't know why.
Lex Fridman (46:19.400)
So maybe this is a good time to bring up consciousness.
Lex Fridman (46:22.400)
Sure.
Sara Walker (46:24.800)
It's been here all along.
Lex Fridman (46:26.600)
Well, has it?
Sara Walker (46:28.200)
So, I mean that's.
Lex Fridman (46:29.040)
At least in this conversation,
Sara Walker (46:30.520)
I think I've been conscious most of it,
Lex Fridman (46:31.920)
but maybe I haven't.
Sara Walker (46:32.760)
Well, yes.
Lex Fridman (46:33.600)
So speak for yourself.
Sara Walker (46:34.800)
You're projecting your consciousness onto me.
Lex Fridman (46:37.960)
You don't know if I'm conscious or not.
Sara Walker (46:39.720)
No, I don't.
Lex Fridman (46:41.060)
You're right.
Sara Walker (46:41.900)
Is that, you talked about the physics of existence,
Lex Fridman (46:45.120)
you talked about the emergence of causality,
Sara Walker (46:50.120)
sorry, you talked about causality and time
Lex Fridman (46:52.720)
being fundamental to the universe.
Lex Fridman (46:55.520)
Where does consciousness fit into all of this?
Lex Fridman (46:58.440)
Like, do you draw any kind of inspiration or value
Sara Walker (47:03.160)
with the idea of panpsychism
Lex Fridman (47:05.400)
that maybe one of the things that we ought to understand
Lex Fridman (47:09.680)
is the physics of consciousness?
Lex Fridman (47:12.040)
Like one of the missing pieces in the physics view
Sara Walker (47:16.680)
of the world is understanding the physics of consciousness.
Lex Fridman (47:20.460)
Or like that word has so many concepts underneath it,
Lex Fridman (47:24.860)
but let's put consciousness as a label
Lex Fridman (47:29.120)
on a black box of mystery that we don't understand.
Lex Fridman (47:32.320)
Do you think that black box holds the key
Lex Fridman (47:36.560)
to finally answering the question
Lex Fridman (47:38.920)
of the physics of life?
Lex Fridman (47:40.760)
The problems are absolutely related.
Sara Walker (47:42.280)
I think most, and I'm interested in both
Lex Fridman (47:44.720)
because I'm just interested in what we are.
Lex Fridman (47:46.320)
And to me, the most interesting feature
Lex Fridman (47:48.140)
of what we are is our minds
Lex Fridman (47:49.460)
and the way they interact with our minds.
Lex Fridman (47:51.320)
Like minds are the most beautiful thing
Sara Walker (47:52.680)
that exists in the universe.
Lex Fridman (47:53.560)
So how do they come to be?
Sara Walker (47:55.360)
Sorry to interrupt.
Lex Fridman (47:56.240)
So when you say we, you mean humans.
Sara Walker (47:58.480)
I mean humans right now, but that's because I'm a human.
Lex Fridman (48:01.560)
Or at least I think I am.
Lex Fridman (48:02.400)
But you think there's something special
Lex Fridman (48:03.680)
to this particular?
Sara Walker (48:05.040)
No, no, no, no, no.
Lex Fridman (48:06.480)
No, I'm not a human centric thinker.
Lex Fridman (48:11.280)
But are you one entity?
Lex Fridman (48:12.560)
You said a bunch of stuff came together to make a Sarah.
Sara Walker (48:15.420)
Like do you think of yourself as one entity
Lex Fridman (48:18.200)
or are you just a bunch of different components?
Lex Fridman (48:20.760)
Like is there any value to understand the physics of Sarah?
Lex Fridman (48:24.400)
Or are you just a bunch of different things
Lex Fridman (48:26.360)
that are like a nice little temporary side effect?
Lex Fridman (48:30.080)
Yeah, you could think of me as a bundle of information
Sara Walker (48:33.040)
that just became temporarily aggregated
Lex Fridman (48:34.840)
into your individual, yeah.
Sara Walker (48:36.520)
That's fine.
Lex Fridman (48:37.340)
I agree with that view.
Sara Walker (48:38.320)
I'll take that as a compliment actually.
Lex Fridman (48:42.200)
But nevertheless, that bundle of information
Sara Walker (48:46.560)
has become conscious.
Lex Fridman (48:47.840)
Or at least keeps calling herself conscious.
Sara Walker (48:51.000)
Yeah, I think I'm conscious right now,
Lex Fridman (48:52.600)
but I might not be, but that's okay.
Sara Walker (48:55.100)
Or you wouldn't know.
Lex Fridman (48:56.360)
So yeah, so this is the problem.
Lex Fridman (48:57.720)
So yeah, usually people when they're talking
Lex Fridman (48:59.640)
about consciousness are worried
Sara Walker (49:00.920)
about the subjective experience.
Lex Fridman (49:02.280)
And so I think that's why you're saying,
Sara Walker (49:04.140)
I don't know if you're conscious
Lex Fridman (49:05.100)
because I don't know if you're experiencing
Sara Walker (49:06.900)
this conversation right now.
Lex Fridman (49:09.280)
And nor do you know if I'm experiencing
Sara Walker (49:11.480)
the conversation right now.
Lex Fridman (49:12.960)
And so this is why this is called
Sara Walker (49:14.280)
the hard problem of consciousness
Lex Fridman (49:15.400)
because it seems impenetrable from the outside
Sara Walker (49:17.520)
to know if something's having a conscious experience.
Lex Fridman (49:21.500)
And I really like the idea of also
Sara Walker (49:24.600)
like the hard problem of matter,
Lex Fridman (49:26.220)
which is related to the hard problem of consciousness,
Sara Walker (49:28.940)
which is you don't know the intrinsic properties
Lex Fridman (49:31.600)
of an electron not interacting,
Sara Walker (49:33.320)
say for example, with anything else in the universe.
Lex Fridman (49:35.240)
All the properties of anything that exists
Sara Walker (49:37.680)
in the universe are defined by its interaction
Lex Fridman (49:39.480)
because you have to interact with it
Sara Walker (49:40.920)
in order to be able to observe it.
Lex Fridman (49:42.440)
So we can only actually know the things
Sara Walker (49:44.520)
that are observable from the outside.
Lex Fridman (49:46.260)
And so this is one of the reasons
Sara Walker (49:47.720)
that consciousness is hard for science
Lex Fridman (49:49.400)
because you're asking questions
Sara Walker (49:51.080)
about something that's subjective
Lex Fridman (49:52.720)
and supposed to be intrinsic to what that thing is
Sara Walker (49:55.460)
as it exists and how it feels about existing.
Lex Fridman (49:59.200)
And so I have thought a lot about this problem
Lex Fridman (50:02.520)
and its relationship to the problem of life.
Lex Fridman (50:05.400)
And the only thing I can come up with
Sara Walker (50:07.160)
to try to make that problem scientifically tractable
Lex Fridman (50:12.920)
and also relate it to how I think about the physics of life
Sara Walker (50:17.920)
is to ask the question,
Lex Fridman (50:20.320)
are there things that can only happen in the universe
Sara Walker (50:23.480)
because there are physical systems
Lex Fridman (50:26.240)
that have subjective experience?
Lex Fridman (50:28.760)
So does subjective experience have different causes
Lex Fridman (50:32.640)
that things that it can cause to occur
Lex Fridman (50:36.320)
that would happen in the absence of that?
Lex Fridman (50:38.600)
I don't know the answer to that question,
Lex Fridman (50:40.080)
but I think that's a meaningful way
Lex Fridman (50:42.080)
of asking the question of consciousness.
Sara Walker (50:43.600)
I can't ask if you're having experience right now,
Lex Fridman (50:46.600)
but I can ask if you having experience right now
Sara Walker (50:49.160)
changes something about you
Lex Fridman (50:50.840)
and the way you interact with the world.
Lex Fridman (50:53.760)
So does stuff happen?
Lex Fridman (50:56.400)
It's a good question to ask, does stuff happen
Lex Fridman (50:59.000)
if consciousness is?
Lex Fridman (51:01.360)
Then it's a real physical thing, right?
Sara Walker (51:03.160)
It has physical consequences.
Lex Fridman (51:04.440)
I'm a physicist, I'm biased,
Lex Fridman (51:05.640)
so I can't get rid of that bias.
Lex Fridman (51:08.200)
It's really deeply ingrained.
Sara Walker (51:10.320)
I've tried, but it's hard.
Lex Fridman (51:12.080)
But I mean, you're saying information is physical too.
Lex Fridman (51:14.640)
So like virtual reality, simulation,
Lex Fridman (51:16.400)
all that program is physical too in the sense of.
Sara Walker (51:18.280)
Yes, everything's physical.
Lex Fridman (51:19.400)
It's just not physical the way it's represented in our minds.
Sara Walker (51:22.900)
Right, so you, I love your Twitter.
Lex Fridman (51:25.520)
So you tweet these like deep thoughts, deep thoughts.
Sara Walker (51:29.720)
That's what a theorist does
Lex Fridman (51:30.680)
when she's trying to experiment.
Lex Fridman (51:33.320)
Is tweet?
Lex Fridman (51:34.160)
Yes.
Sara Walker (51:35.000)
It's just like sitting there.
Lex Fridman (51:36.320)
I mean, I could just imagine you sitting there
Sara Walker (51:38.360)
for like hours and all of a sudden just like
Lex Fridman (51:40.360)
this thought comes out and you get a little
Sara Walker (51:44.440)
like inkling into the thought process.
Lex Fridman (51:46.840)
Yeah, usually it's like when I'm running between things
Lex Fridman (51:48.840)
and not so much when I've had deep thoughts.
Lex Fridman (51:50.960)
Well, yeah, so you.
Sara Walker (51:52.280)
Deep thoughts are hard to articulate.
Lex Fridman (51:53.640)
One of the things you tweeted is,
Sara Walker (51:55.320)
ideologically, there are many parallels
Lex Fridman (51:57.640)
between the search for neural correlates of consciousness
Lex Fridman (52:01.640)
and for chemical correlates of life.
Lex Fridman (52:04.260)
How the neuroscience and astrobiology communities
Sara Walker (52:07.480)
treat those correlates is entirely different.
Lex Fridman (52:10.460)
Can you elaborate against this kind of the parallels?
Sara Walker (52:14.660)
It has to do a little bit with the consciousness
Lex Fridman (52:16.520)
and the matter thing you're talking about.
Sara Walker (52:20.080)
Yeah, it does.
Lex Fridman (52:20.960)
And I can't remember what state of mind I was
Sara Walker (52:23.000)
when I was actually thinking about that.
Lex Fridman (52:24.400)
But I think part of it is.
Sara Walker (52:27.120)
I bet you never thought you were gonna have
Lex Fridman (52:28.640)
to analyze your own tweets.
Sara Walker (52:29.920)
No, I didn't.
Lex Fridman (52:31.040)
It's an interesting historical juxtaposition of thinking.
Lex Fridman (52:35.120)
So the tweet is a historical.
Lex Fridman (52:38.200)
You're doing an assembly experiment right now
Sara Walker (52:40.200)
because you're bringing a thought from the past
Lex Fridman (52:41.600)
into the present and trying to actually.
Sara Walker (52:43.240)
In a lab.
Lex Fridman (52:44.200)
Yeah, yeah, yeah.
Sara Walker (52:45.440)
This is experimental science right here
Lex Fridman (52:47.560)
on the podcast live.
Lex Fridman (52:51.040)
So go, let's see how the consciousness evolves on this one.
Lex Fridman (52:53.720)
Yeah, so in neuroscience, it's kind of accepted
Sara Walker (52:57.680)
that we can't get at the subjective aspect
Lex Fridman (53:00.480)
of consciousness.
Lex Fridman (53:01.540)
So people are very interested in what would be a correlate
Lex Fridman (53:05.280)
of consciousness.
Sara Walker (53:06.120)
So.
Lex Fridman (53:08.840)
What's a correlate?
Sara Walker (53:09.680)
A correlate is a feature that relates
Lex Fridman (53:13.240)
to conscious activity.
Lex Fridman (53:14.420)
So for example, a verbal report is a correlate
Lex Fridman (53:18.660)
of consciousness because I can tell you when I'm conscious.
Lex Fridman (53:22.880)
And then when I'm sleeping, for example,
Lex Fridman (53:25.000)
I can't tell you I'm conscious.
Lex Fridman (53:26.200)
So we have this assumption that you're not conscious
Lex Fridman (53:28.680)
when you're sleeping and you're conscious when you're awake.
Lex Fridman (53:31.840)
And so that's sort of like a very obvious example,
Lex Fridman (53:35.480)
but neuroscientists, which I'm no neuroscientist
Lex Fridman (53:38.840)
and I'm not an expert in this field.
Lex Fridman (53:40.120)
So, but they have very sophisticated ways of measuring
Sara Walker (53:43.720)
activity in our brain and trying to relate that
Lex Fridman (53:45.960)
to verbal report and other proxies for whether someone
Sara Walker (53:49.560)
is experiencing something.
Lex Fridman (53:51.600)
And that's what is meant by neural correlates.
Lex Fridman (53:54.720)
And then, so when people are trying to think
Lex Fridman (53:57.320)
about studying consciousness or developing theories
Sara Walker (54:02.400)
for consciousness, they often are trying to build
Lex Fridman (54:06.160)
an experimental bridge to these neural correlates,
Sara Walker (54:09.780)
recognizing the fact that a neural correlate
Lex Fridman (54:11.960)
may or may not correspond to consciousness
Sara Walker (54:15.120)
because that problem's hard
Lex Fridman (54:16.640)
and there's all these associated issues to it.
Lex Fridman (54:19.800)
So that's, from a neuroscience perspective,
Lex Fridman (54:22.120)
it's like fake it till you make it.
Lex Fridman (54:23.560)
So you. Pretty much, yeah.
Lex Fridman (54:24.760)
You fake whatever the correlates are and hopefully
Sara Walker (54:27.600)
that's going to summon the thing that is consciousness.
Lex Fridman (54:32.600)
Yeah, something like that.
Lex Fridman (54:33.440)
And so the same thing on the chemical correlates of life.
Lex Fridman (54:37.960)
That sounds like, that's an awesome concept.
Lex Fridman (54:39.880)
Is that something that people?
Lex Fridman (54:41.240)
No, I just made that up.
Sara Walker (54:42.280)
Okay.
Lex Fridman (54:43.120)
That was original to that tweet.
Sara Walker (54:43.960)
You can cite the tweet.
Lex Fridman (54:45.600)
Maybe I'll write it in a paper someday.
Sara Walker (54:48.300)
Chemical correlates of life, that's a good title.
Lex Fridman (54:50.600)
I mean, first of all, your paper is true
Sara Walker (54:52.920)
that people should check out, have great titles.
Lex Fridman (54:55.520)
Thank you.
Sara Walker (54:56.360)
Or papers you're involved with.
Lex Fridman (54:58.120)
So your tweets and titles are stellar and also your ideas,
Lex Fridman (55:02.600)
but the tweets and titles are much more important.
Lex Fridman (55:04.920)
Of course.
Sara Walker (55:06.000)
So. Ideas will live longer.
Lex Fridman (55:08.640)
Yeah.
Sara Walker (55:10.000)
They're much more diffused though.
Lex Fridman (55:12.240)
Well, it's, yeah, it's the Trojan,
Sara Walker (55:13.960)
the tweet is the Trojan horse of the idea
Lex Fridman (55:16.040)
that sticks on for a long time.
Sara Walker (55:18.020)
Okay, so is there anything to say
Lex Fridman (55:19.400)
about the chemical correlates of life?
Sara Walker (55:20.840)
You're saying they're similar kind of ways
Lex Fridman (55:24.200)
of thinking about it,
Lex Fridman (55:25.700)
but you mentioned about the communities.
Lex Fridman (55:30.600)
Yeah, so I think in astrobiology, it's not,
Sara Walker (55:35.500)
there's no concept of chemical correlates of life.
Lex Fridman (55:37.760)
We don't think about it that way.
Sara Walker (55:38.960)
We think if we find molecules that are involved in biology,
Lex Fridman (55:42.800)
we found life.
Lex Fridman (55:44.480)
So I think one of my motivations there
Lex Fridman (55:48.000)
was just to separate the fact
Sara Walker (55:49.200)
that life has abstract properties associated to it.
Lex Fridman (55:53.120)
They become imprinted in material substrates
Lex Fridman (55:57.320)
and those substrates are correlates for that thing,
Lex Fridman (55:59.500)
but they are not necessarily
Sara Walker (56:00.840)
the thing we're actually looking for.
Lex Fridman (56:02.020)
The thing that we're looking for is the physics
Sara Walker (56:04.000)
that's organizing that system to begin with,
Lex Fridman (56:05.840)
not the particular molecules.
Sara Walker (56:08.320)
In the same sense that, you know,
Lex Fridman (56:10.000)
your consciousness is not your brain.
Sara Walker (56:13.200)
It's instantiated in your brain.
Lex Fridman (56:16.740)
You know, it has to have a physical substrate,
Lex Fridman (56:18.760)
but it's not, the matter is not the thing
Lex Fridman (56:21.560)
that you're looking at.
Sara Walker (56:22.400)
It's some other, at least not in the way
Lex Fridman (56:24.300)
that we have come to look at matter,
Sara Walker (56:26.780)
you know, with traditional physics and things.
Lex Fridman (56:28.600)
There's something else there
Lex Fridman (56:29.600)
and it might be this feature of history
Lex Fridman (56:31.120)
I was talking about,
Sara Walker (56:31.960)
our time being actually, you know,
Lex Fridman (56:33.840)
physically represented there.
Lex Fridman (56:35.840)
Do you think consciousness can be engineered?
Lex Fridman (56:38.600)
Yes.
Lex Fridman (56:40.060)
In the same way that life can be engineered?
Lex Fridman (56:41.400)
Well, that was a fast answer.
Sara Walker (56:42.400)
I didn't even think about that.
Lex Fridman (56:43.360)
That's interesting.
Sara Walker (56:44.640)
You don't have a free will.
Lex Fridman (56:45.920)
That was predestined.
Sara Walker (56:46.760)
No, I do have free will,
Lex Fridman (56:47.580)
but it's interesting,
Sara Walker (56:48.420)
because I mean, you know,
Lex Fridman (56:50.920)
Now you're backtracking.
Sara Walker (56:51.920)
No, no.
Lex Fridman (56:52.760)
And that was predestined.
Sara Walker (56:53.720)
Yeah, no, no.
Lex Fridman (56:55.760)
No, I do believe in free will,
Lex Fridman (56:56.960)
but I also think that there's kind of an interesting,
Lex Fridman (57:00.640)
you know, like what you're speaking about consciousness.
Lex Fridman (57:03.240)
What are you consciously aware of
Lex Fridman (57:04.560)
versus like what is your subconscious brain
Lex Fridman (57:07.540)
actually processing and doing?
Lex Fridman (57:08.840)
And sometimes there's conflict between your consciousness
Lex Fridman (57:12.080)
and your subconsciousness
Lex Fridman (57:13.080)
or your consciousness is a little slower
Sara Walker (57:14.840)
than your subconscious.
Lex Fridman (57:16.180)
And intuition is a really important feature of that.
Lex Fridman (57:18.720)
And so a lot of the ways I do my science
Lex Fridman (57:20.520)
is guided by intuition.
Lex Fridman (57:22.280)
So when I give fast answers like that,
Lex Fridman (57:23.820)
I think it's usually
Sara Walker (57:24.660)
because I haven't really thought about them
Lex Fridman (57:25.760)
and therefore that's probably telling me something.
Sara Walker (57:29.040)
Let's continue the deep analysis of your tweets.
Lex Fridman (57:33.280)
You said that determinism in a tweet,
Sara Walker (57:35.880)
determinism and randomness play important roles
Lex Fridman (57:38.520)
in understanding what life is.
Lex Fridman (57:40.560)
So let me ask on this topic of free will,
Lex Fridman (57:42.520)
what is determinism, what is randomness
Lex Fridman (57:45.680)
and why the heck do they have anything to do
Lex Fridman (57:48.200)
with understanding life?
Sara Walker (57:50.240)
Yeah, and you threw free will in there,
Lex Fridman (57:52.600)
just throwing all the stuff in the bag.
Lex Fridman (57:55.000)
Are they not related, determinism and randomness?
Lex Fridman (57:56.120)
No, no, they are related.
Sara Walker (57:58.080)
No, no, that's all right.
Lex Fridman (57:59.120)
I was being unfair.
Sara Walker (58:00.320)
You didn't even capitalize the tweet, by the way.
Lex Fridman (58:02.280)
It was all lowercase.
Sara Walker (58:03.540)
I must've been angry.
Lex Fridman (58:05.120)
Oh, that was saying,
Lex Fridman (58:06.320)
can you analyze the emotion behind that?
Lex Fridman (58:08.160)
No, I actually did.
Lex Fridman (58:09.000)
Is it frustration or is it hope?
Lex Fridman (58:09.840)
Yeah, maybe.
Lex Fridman (58:10.860)
So I already argued that I don't think that can happen
Lex Fridman (58:14.200)
without that whole causal history.
Lex Fridman (58:16.120)
And so I guess in some sense,
Lex Fridman (58:18.440)
the determinism for me arises because of the causal history.
Lex Fridman (58:23.440)
And I'm not really sure actually
Lex Fridman (58:25.280)
about whether the universe is random or deterministic.
Sara Walker (58:29.000)
I just had this sort of intuition for a long time.
Lex Fridman (58:32.120)
I'm not sure if I agree with it anymore,
Lex Fridman (58:34.060)
but it's still kind of lingering
Lex Fridman (58:35.360)
and I don't know what to do with this question.
Lex Fridman (58:37.200)
But it seems to me, you know,
Lex Fridman (58:39.000)
so you asked the question, what is life?
Lex Fridman (58:41.400)
But you could also, why life?
Lex Fridman (58:42.840)
Why does life exist?
Lex Fridman (58:43.680)
What does the universe need life for?
Lex Fridman (58:45.600)
Not that the universe has needs,
Lex Fridman (58:46.800)
but you know, we have to anthropocentrize things sometimes
Lex Fridman (58:48.880)
to talk about them.
Lex Fridman (58:50.360)
And I had this feeling that if it was possible
Lex Fridman (58:53.840)
for a cup or a desk ornament or a phone on Mars
Sara Walker (58:57.240)
to spontaneously fluctuate into existence,
Lex Fridman (58:59.520)
the universe didn't need life to create those objects.
Sara Walker (59:01.760)
It wasn't necessary for their existence.
Lex Fridman (59:03.340)
It was just a random fluke event.
Lex Fridman (59:05.640)
And so somehow to me,
Lex Fridman (59:06.880)
it seems that it can't be that those things
Sara Walker (59:09.800)
formed by random processes,
Lex Fridman (59:11.820)
they actually have to have a set of causes
Sara Walker (59:14.160)
that accrue and form those things
Lex Fridman (59:17.280)
and they have to have that history.
Lex Fridman (59:18.820)
And so it seems to me that that life
Lex Fridman (59:21.000)
was somehow deeply related to the question
Sara Walker (59:24.080)
of whether the underlying rules of our universe
Lex Fridman (59:26.560)
had randomness in them or they were fully deterministic.
Lex Fridman (59:29.080)
And in some ways you can think about life
Lex Fridman (59:30.600)
as being the most deterministic part of physics
Sara Walker (59:33.880)
because it's where the causes are precise in some sense.
Lex Fridman (59:39.320)
Or most stable.
Lex Fridman (59:40.320)
So like I'm trying...
Lex Fridman (59:41.160)
Most stable, yes, most reliable.
Sara Walker (59:42.960)
Most reliable for the tools of physics.
Lex Fridman (59:47.120)
But where's the randomness come from then?
Sara Walker (59:50.680)
Okay, so you were speaking with...
Lex Fridman (59:54.400)
I've gone in a tangent,
Lex Fridman (59:55.760)
so I'm not sure where we are in the...
Lex Fridman (59:57.040)
Yeah.
Sara Walker (59:58.840)
All of the universe is a kind of tangent.
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