Sara Walker
Astrobiologist and theoretical physicist at Arizona State University, working on assembly theory and the physics of life.
Sara Walker did not write this page.
We collected these quotes from things they published elsewhere, and every quote links to where it was said. They have no account here and have not endorsed this site. Quotes are word for word; the short line under each one is our own restatement, not their wording. Their own site. Is this you? Claim it or ask us to remove it. Or tell us what is wrong here.
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Their wordsI think life obeys universal principles. I think there is some deep underlying explanatory framework that will tell us about the nature of life in the universe and will allow us to identify life that we can’t yet recognize because it’s too different.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 1st of 22 in this recording
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Their wordsThat’s one of these standard different definitions that a lot of people in my field like to use in astrobiology is life as a self-sustaining chemical system capable of Darwinian evolution, which I was once quoted as agreeing with, and I was really offended because I hate that definition. I think it’s terrible, and I think it’s terrible that people use it. I think every word in that definition is actually wrong as a descriptor of life.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 2nd of 22 in this recording
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Their wordsAnd then you can go to chemical system. I don’t think that’s good either. I think there’s a confusion because life emerges in chemistry that life is chemical. I don’t think life is chemical. I think life emerges in chemistry because chemistry is the first thing the universe builds where it cannot exhaust all the possibilities, because the combinatorial space of chemistry is too large.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 3rd of 22 in this recording
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Their wordsOh, if it’s not chemical. So I think some of the things that have evolved on our biosphere I would call as much alive as chemistry, as a cell, but they seem much more abstract. So for example, I think language is alive, or at least life. I think memes are.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 4th of 22 in this recording
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Their wordsBut mathematics too, and it’s interesting because people think that math has this Platonic reality that exists outside of our universe, and I think it’s a feature of our biosphere and it’s telling us something about the structure of ourselves.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 5th of 22 in this recording
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Their wordsAnd so for me, I think life is the process of how information structures matter over time and space, and an example of life is what emerges on a planet and yields an open-ended cascade of generation of structure and increasing complexity. And this is the thing that life is. And any individual is just a particular instance of these lineages that are structured across time.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 6th of 22 in this recording
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Our reading
Living things are among the largest objects in the universe — not large in space, but large in time.
Their wordsAnd so what I’m getting at with this is I think that living objects are actually huge. They’re some of the biggest structures in the universe, but they are not big in space. They’re big in time. And we actually can’t resolve that feature.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 7th of 22 in this recording
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Our reading
The modern technosphere is the largest object in time that we know of anywhere in the universe.
Their wordsYeah, I think the modern technosphere is the largest object in time in the universe that we know about.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 8th of 22 in this recording
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Our reading
Non-equilibrium physics will not explain life, and entropy has almost nothing to do with it.
Their wordsAnd there’s still a lot of impetus in the physics community to think that non-equilibrium physics will explain life. But I think that’s not the right approach. I don’t think ultimately the solution to what life is there, and I don’t really think entropy has much to do with it unless it’s entirely reformulated.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 9th of 22 in this recording
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Their wordsPhysics hardly even acknowledges that the universe is random at its base. We like to think we live in a deterministic universe and everything’s deterministic. But I think that’s probably an artifact of the way that we’ve written down laws of physics since Newton invented modern physics and his conception of motion and gravity, which he formulated laws that had initial conditions and fixed dynamical laws.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 10th of 22 in this recording
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Their wordsSo what’s fundamental, the way we talk about it in current physics is not actually fundamental, it’s the boundaries of what we can observe in our universe, what we can see with our technology.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 11th of 22 in this recording
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Their wordsI think for me, the frontier in modern physics, where the new physics lies is not in high energy particle physics, it’s not in quantum gravity, it’s not in any of these sort of traditionally sold, “This is going to be the newest deepest insight we have into the nature of reality.” It is going to be in studying the problems of life and intelligence and the things that are sort of also our current existential crises as a civilization or a culture that’s going through an existential trauma of inventing technologies that we don’t understand right now.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 12th of 22 in this recording
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Our reading
Past roughly fifteen assembly steps, the only molecules we ever observe are ones that life made.
Their wordsAnd what Lee’s been able to show in the lab with his team is that for organic chemistry, it’s about 15 steps. And then you only see molecules that the only molecules that we observe that are past that threshold are ones that are in life.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 13th of 22 in this recording
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Their wordsI think it’s actually abrupt. I’ve never been able to say that in my entire career before. I’ve always gone back and forth about whether the original life was gradual or abrupt. I think it’s very abrupt.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 14th of 22 in this recording
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Their wordsThere’s this assumption that computation is at the base of reality, and I see it at the top of reality, not at the base, because I think computation was built by our biosphere. It’s something that happened after many billion years of evolution. It doesn’t happen in every physical object.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 15th of 22 in this recording
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Their wordsIt’s totally fine to have a turtle. Everyone has a turtle. You can’t build a theory without a turtle. It depends on the problem you want to describe. Actually, the reason I can’t get behind Stephen’s ontology is I don’t know what question he’s trying to answer. Without a question to answer, I don’t understand why you’re building a theory of reality.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 16th of 22 in this recording
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Their wordsYeah. I think if you’re thinking about this thinking about living things as these giant causal structures or these objects that are deep in time or whatever language we end up using to describe it seems to me that consciousness is about the fact that we have a conscious experience is because we are these temporally extended objects. Consciousness and the abstraction that we have in our minds is actually a manifestation of all the time that’s rolled up in us.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 17th of 22 in this recording
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Their wordsI think large language models are kind of like the genetic system for language in some sense, where it’s allowing an archiving that’s highly dynamic.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 18th of 22 in this recording
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Their wordsOr is it really that we’re building some super machine in a box that’s going to be smart and kill everybody? It’s not even a science fiction narrative. It’s a bad science fiction narrative. I just don’t think it’s actually accurate to any of the technologies we’re building or the way that we should be describing them.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 19th of 22 in this recording
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Their wordsSo death is a way to make room in the universe for other things to exist that wouldn’t be able to exist otherwise.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 20th of 22 in this recording
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Their wordsSo my interpretation of reality is if you fold it up, all that bifurcation of many worlds, and you just fold it into the structure that is you, and you just said you are all of those many worlds and your history converged on you, but you’re actually an object exists that was selected to exist, and you’re self-consistent with the other structures. So the quantum mechanical reality is not the one that you live in. It’s this very deterministic, classical world, and you’re carving a path through that space. But I don’t think that you’re constantly branching into new spaces. I think you are that space.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 21st of 22 in this recording
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Their wordsIt’s the fact that you’re a deterministic structure living in a random background. And also, all of that selection bundled in you allows you to select on possible futures. So that’s where your will comes from.
↗Sara Walker: Physics of Life, Time, Complexity, and Aliens | Lex Fridman Podcast #433youtube.com 22nd of 22 in this recording