Speaker 1: Quick note before today's episodes to let you know about
Speaker 1: my new book, Do Aliens Speak Physics, which is available
Speaker 1: for pre order now and can be at your house
Speaker 1: on November fourth. It's all about my favorite scenario, aliens
Speaker 1: arriving on Earth and what it would be like to
Speaker 1: try to talk to them about physics. Is that really possible?
Speaker 1: We don't know, but the book is a fun exploration
Speaker 1: of the potential challenges. If you've enjoyed my science outreach,
Speaker 1: this is a nice way to support me. Check it
Speaker 1: out at www dot alienspeakphysics dot com. Okay, on to
Speaker 1: today's episode. I like to think about alien life, But
Speaker 1: where are they all? If aliens are so rife.
Speaker 2: If you don't metabolize and reproduce, then science says you're dead.
Speaker 2: Does a recently discovered critter turn this definition on its head?
Speaker 1: A curious listener wants to know what would the universe
Speaker 1: be like if light were very slow?
Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's
Speaker 2: answers will make it right.
Speaker 1: Welcome to Daniel and Kelly's Extraordinary Universe.
Speaker 2: Hello. I'm Kelly Wader Smith. I study parasites and space,
Speaker 2: and I'm excited that we're talking about aliens today. And
Speaker 2: the reason I'm excited about that is because I'm really
Speaker 2: excited about this book that's coming out called Do Aliens
Speaker 2: Speak Physics?
Speaker 1: Oh my gosh, for a moment, I thought you were
Speaker 1: going to tell me about another book about aliens, so
Speaker 1: it's going to scoop mine. Oh no, my nightmare. Hi.
Speaker 1: I'm Daniel. I'm a particle physicist, and I do love
Speaker 1: thinking about aliens because I worry that the way we
Speaker 1: do science is somehow infected with our humanity and there's
Speaker 1: somebody out there getting deeper at the truth of the.
Speaker 2: Matter infected by our humanity. That is a like surprisingly
Speaker 2: negative view from you.
Speaker 1: I think I was trying to speak biology, you know,
Speaker 1: like you know, it's trying to use some sort of
Speaker 1: parasitical language there.
Speaker 2: I think you're implying that we're all like pessimists and negative.
Speaker 2: But you know I am. So that's that's fine with me.
Speaker 1: Well, thank you for bringing up my book, which is
Speaker 1: coming out in November. It's called Do Aliens Speak Physics?
Speaker 1: And you can get it all fine booksellers and probably
Speaker 1: several others. And you're right that it's a little bit
Speaker 1: pessimistic because the book is in response to my concern
Speaker 1: that we were sort of putting ourselves at the center
Speaker 1: of the universal intellectual stage by saying, like, everything we've
Speaker 1: discovered is true, it's real, you know, it's universal that
Speaker 1: other scientists around the galaxy will find the same thing.
Speaker 1: To me, that smacks a little bit of like the
Speaker 1: Earth is the center of the solar system or the universe,
Speaker 1: you know, or we are important somehow on a cosmic stage.
Speaker 1: And so I just wanted to ask, like, well, is
Speaker 1: that really true? Are there ways that our humanity has
Speaker 1: affected in our science? And so that's what the book
Speaker 1: is about, is what aliens do physics differently? And how
Speaker 1: could we know?
Speaker 2: And at a future date we will have a whole
Speaker 2: episode talking about that question and what you learned while
Speaker 2: you were researching that problem. But today I wanted to
Speaker 2: ask you what is your favorite part of writing a book?
Speaker 1: Very part of writing a book. Oh, it's definitely not
Speaker 1: coming up with the title. I don't know why, but
Speaker 1: that's so frustrating. It's so hard to capture everything about
Speaker 1: the book in a few words. You know, you have
Speaker 1: to like meet the reader where they are, get them interested,
Speaker 1: tell them a little bit about the book. Also, it
Speaker 1: should be like clever in some way. So, boy, that
Speaker 1: is really tough. And you and I have had lots
Speaker 1: of conversations and titles. It's tricky. Yeah, it's tricky. I
Speaker 1: think my favorite two parts of writing a book are
Speaker 1: having the initial idea, Like it's always fun to come
Speaker 1: up with a new idea for a project, you know,
Speaker 1: as an academic, Like new projects are shiny and fun,
Speaker 1: and current projects are like, ugh, man, I just to
Speaker 1: get that thing.
Speaker 2: Finished, got to get it up the door.
Speaker 1: But also the research, like I love digging in deep
Speaker 1: and reading a bunch of papers, and I wonder sometimes
Speaker 1: like why didn't I just do this before? But for
Speaker 1: some reason, like having a reason to dig in and
Speaker 1: to read up about it and to learn about it.
Speaker 1: If that excuses like I'm writing a book about this,
Speaker 1: or I'm doing research for a listener or something. It's
Speaker 1: easier to do, it's more fun. It feels like you're
Speaker 1: allowed to do it instead of you just goofing off
Speaker 1: and reading philosophy papers.
Speaker 2: I absolutely agree with you, and that is also why
Speaker 2: I love our Listener Questions segment so much, is that
Speaker 2: we whenever a question comes across my inbox where I'm like, oh,
Speaker 2: I want to know more about that than I'm like,
Speaker 2: that immediately goes in the listener questions pile. And then
Speaker 2: while I'm researching it, I don't feel like I'm slacking off.
Speaker 2: I'm doing my quote unquote work and it's awesome.
Speaker 1: There you go. And so, is that also your favorite
Speaker 1: part of writing a book? The deep research dive?
Speaker 2: The two things I hate the most. I always write
Speaker 2: the title last because I hate it, I agree, And
Speaker 2: then I hate the part where I'm supposed to promote
Speaker 2: the book and ask people for favors, And that's my
Speaker 2: least favorite part, but it's part of the job. But no,
Speaker 2: my favorite is just getting to do the research and
Speaker 2: learning about new stuff, which is why I so rarely
Speaker 2: write books about things I already know about, because I'd
Speaker 2: rather have an excuse to read about something new and
Speaker 2: like going through space law textbooks. On the one hand,
Speaker 2: there were days where I'm like, why do I enjoy.
Speaker 1: This so much?
Speaker 2: Do I enjoy this? I'm not sure, I'm on the fence.
Speaker 2: Then at the end of the day I'd be like,
Speaker 2: oh my gosh, I just learned about like the laws
Speaker 2: governing and the cosmos and that's pretty cool, and also
Speaker 2: how they are inadequate, and so yeah, it's a fun
Speaker 2: research topic.
Speaker 1: I think it's also really fun to discover the things
Speaker 1: that are interesting to you. And you've done a day
Speaker 1: of reading and then you come to dinner with a
Speaker 1: family and you're like excited to talk about some nerdy
Speaker 1: detail you read about that was really cool, or some
Speaker 1: new critter or some crazy idea you thought about and
Speaker 1: had never considered before. It shows you, like which parts
Speaker 1: of the universe inspire you and connect with you. And
Speaker 1: that's what I love about science, that there's just so
Speaker 1: much like that we just find cool. I mean, it's
Speaker 1: an emotional response, right, And this is actually one of
Speaker 1: the things I'm curious about aliens, Like do aliens have
Speaker 1: the same emotional reaction to the mysteries of the universe?
Speaker 1: Are they curious? Do they care? Right? Is that human
Speaker 1: or is that universal? That's like a very basic question
Speaker 1: we don't know the answer to, but for me, it's
Speaker 1: one of my favorite things about being human.
Speaker 2: Yeah. Yeah, Well, and what I want to know is
Speaker 2: do they care about us? Yeah, which leads us nicely
Speaker 2: into our first question from a listener, So let's go
Speaker 2: ahead and hear that question.
Speaker 3: Hi, I'd love to hear your thoughts about the Fermi paradox.
Speaker 3: Is it really a paradox? While I think the theory
Speaker 3: is about the great filter, like if there's some big
Speaker 3: thing that always prevents beings from reaching interstellar travel. I
Speaker 3: think that's a really interesting thought experiment. But in general,
Speaker 3: I've never really seen the Fermi paradox as a true paradox,
Speaker 3: just do to how big the universe is and how
Speaker 3: spread out everything is, like the odds of two kinds
Speaker 3: of intelligent life. Somehow intercepting just feels too unlikely not
Speaker 3: to mention the significant time delay. Like if alien friends
Speaker 3: from thirty thousand light years away, which is, you know,
Speaker 3: relatively our neighbors on the scale of the universe, if
Speaker 3: they sent out a signal right now, or even one
Speaker 3: hundred years ago or a thousand years ago, we're not
Speaker 3: getting that signal for tens of thousands of years. Still,
Speaker 3: Am I right to think that this isn't really a paradox?
Speaker 3: Or am I misunderstanding something or not thinking about it correctly.
Speaker 3: I'd be happy to be proved wrong here, So I'm
Speaker 3: looking forward to your answer, thank you.
Speaker 2: Yay, all right, Daniel, So tell us about the Fermi paradox,
Speaker 2: which in an earlier version of the book that I
Speaker 2: read explains the Fermi paradox. So if anyone wants to
Speaker 2: dive deeper, they should check out your book. I assume
Speaker 2: it's still in there.
Speaker 1: Yeah, So the Fermi paradox quickly is essentially asking, hey,
Speaker 1: the galaxy is filled with stars and planets. There are
Speaker 1: hundreds of billions of stars, and we now know that
Speaker 1: most of them have planets and many planets, and so
Speaker 1: there are tens of billions at least of rocky planets
Speaker 1: around stars, which are a lot of places for aliens
Speaker 1: to form and to learn and to develop technology and
Speaker 1: to send us messages or to come visit us. And
Speaker 1: space is big, but the Milky Way is not that
Speaker 1: big compared to its age. I mean, the Milky Way
Speaker 1: is like one hundred thousand light years across, so it
Speaker 1: would take a long time to traverse it. But you know,
Speaker 1: a long time is a few million years, and the
Speaker 1: Milky Way is billions and billions of years old. We
Speaker 1: think more than ten billion years old, and we've been
Speaker 1: here for several billion. Of course, humanity is younger than that.
Speaker 1: But you can imagine scenarios where aliens have traversed the
Speaker 1: galaxy and left relics or filled it with messages. It's
Speaker 1: not that difficult to imagine. So the question is where
Speaker 1: is everybody? Why haven't we been contacted by aliens or
Speaker 1: visited by aliens? So this famously and probably apocryphally, is
Speaker 1: something Fermi said at lunch at Los Almos about fifty
Speaker 1: or sixty years ago, and people have been wondering about since.
Speaker 2: But he did at some point make an equation, right,
Speaker 2: So it maybe started as a lunch conversation, but where
Speaker 2: did the equation come from?
Speaker 1: So this is an equation by Drake. That's the Drake
Speaker 1: equation that tries to calculate how many aliens should be
Speaker 1: contacting us. And it's pretty simple as an equations go.
Speaker 1: It's just a multiplication of a bunch of factors. But
Speaker 1: there's actually a lot you can learn just from the
Speaker 1: structure of the equation. So the equation is like the
Speaker 1: number of stars times the fraction that have planets, times
Speaker 1: the fraction that might have life, times the fraction that
Speaker 1: might be civilized, times of fraction you know that develop
Speaker 1: technology and I don't remember exactly the structure of the terms,
Speaker 1: but the fact that they're multiplied together is important because
Speaker 1: that emphasizes that to hear from aliens, all of those
Speaker 1: factors have to be non zero. Like, it doesn't matter
Speaker 1: if the universe is filled with life, if none of
Speaker 1: it is technological, right, if there's life everywhere but it's
Speaker 1: all just like sheets of algae or heaps of microbes,
Speaker 1: then we're not hearing from anybody, we're not getting visited.
Speaker 1: Or if they become intelligent, but none of them ever
Speaker 1: developed technology, for example, So all of those things have
Speaker 1: to work. All of those factors have to be non
Speaker 1: zero for us to hear. And we know that the
Speaker 1: number of planets is large, number of stars is large.
Speaker 1: We don't know, for example, what is the fraction of
Speaker 1: those planets that have life on them. We know there's
Speaker 1: one hours, but it could be the only one, and
Speaker 1: the denominator is large, So it could be that the
Speaker 1: fraction of planets with life on them is like one
Speaker 1: over a gazillion, in which case we're the only life
Speaker 1: in the Milky Way. Or it could be fifty percent,
Speaker 1: you know, or ten percent, so that the Milky Way
Speaker 1: is filled with life. We just don't know so many
Speaker 1: of these fractions.
Speaker 2: So Julie asks something about the Great Filter. What does
Speaker 2: the Great filter mean?
Speaker 1: Yeah, the Great filters suggests that there might be life everywhere,
Speaker 1: and there might even be intelligent and civilized life everywhere,
Speaker 1: but it might not just last very long. That civilizations
Speaker 1: might essentially burn themselves out. And there's a few ways
Speaker 1: that this could happen. You know, civilizations might become technological
Speaker 1: and then develop the means to kill themselves and end
Speaker 1: up basically nuking each other. And that might be like
Speaker 1: a trend that happens, not in the sense that it's
Speaker 1: inevitable or that it has to happen necessarily. You could
Speaker 1: never prove that, but it might be something that's fairly common.
Speaker 1: Or it could be that civilizations pollute their atmospheres right
Speaker 1: or cause global warming, or in some other way end
Speaker 1: up killing themselves off. So that's the idea of the
Speaker 1: Great Filter to explain the lack of contact or observation
Speaker 1: of aliens by saying that life is very short lived,
Speaker 1: and remember time is very very deep, and so even
Speaker 1: if there have been a thousand civilizations in the Milky Way,
Speaker 1: if each of them only lasted a few thousand years,
Speaker 1: like the length of human civilization so far. Then in
Speaker 1: space of billions of years, it's very unlikely that we
Speaker 1: would hear from them now, or that we would happen
Speaker 1: to be in life at the right moment to receive
Speaker 1: messages from them.
Speaker 2: Okay, that's kind of a bummer, which is right up
Speaker 2: my alley. So what do you think the answer is?
Speaker 1: So now we have to depart from well founded science,
Speaker 1: right and just speculate because we just don't know and
Speaker 1: everything we're doing. I've heard a lot of you know,
Speaker 1: semi scientific analyzes of these things, but in the end,
Speaker 1: we're always extrapolating from one example, and you can learn
Speaker 1: things from one example. You could say like life didn't
Speaker 1: take very long to develop on Earth, so maybe it's
Speaker 1: not unusual, whereas intelligence did take a long time to
Speaker 1: develop on Earth, so maybe that is weird and rare.
Speaker 1: Like you can do those analyzes, but in the end,
Speaker 1: it's just one. You know. It's like if you roll
Speaker 1: a die with a million sides on it and you
Speaker 1: get a six, You're like, hmm, that's kind of a
Speaker 1: weird number. But you'd like another roll, right, You'd like
Speaker 1: more measurements before you decide if the die is fair
Speaker 1: or not. So you know, everything we're we talk about
Speaker 1: now is non scientific extrapolation and really just wish fulfillment.
Speaker 1: But that doesn't mean we can't do it, you know.
Speaker 1: And so my sense is that we're not great at
Speaker 1: imagining the scope of possibilities. Right. We tend to do
Speaker 1: perturbation theory basically, take our example and tweak it a
Speaker 1: little bit. And you know, that's what people did for
Speaker 1: a star trek, like you know, Klingons are humans with
Speaker 1: weird foreheads or Vulcans are humans with weird ears. Right,
Speaker 1: we tend to start from our example and then go
Speaker 1: off in some direction. But aliens are not limited by that.
Speaker 1: They don't have to start from humanity and then tweak it.
Speaker 1: They can start from a completely different place. And because
Speaker 1: we have only one example, it's very likely that we're
Speaker 1: not considering the full landscape. And so the short answer is,
Speaker 1: I expect aliens are going to be way more alien
Speaker 1: than we can even imagine, in ways that would prevent
Speaker 1: them from wanting to contact us, or from having what
Speaker 1: we would recognize as civilization or technology, or to send
Speaker 1: us messages that we don't even interpret or notice or
Speaker 1: understand to be alien. So my favorite explanation for the
Speaker 1: firmi paradox is in that direction that aliens are too alien.
Speaker 2: Interesting. So Eric Kershenbaum wrote Zoologists Guide to the Galaxy
Speaker 2: and great book. Great book, And you know, one of
Speaker 2: the arguments there is that you might expect to find
Speaker 2: organisms to have happened upon some of the same solutions
Speaker 2: that we see here are on earth, because probably the
Speaker 2: principles of natural selection act the same no matter where
Speaker 2: you are, and there are similar pressures and a lot
Speaker 2: of environmental pressures in a lot of different places. And
Speaker 2: so why give me some examples then of what you're thinking,
Speaker 2: and like why you expect things will be so different.
Speaker 1: So, first of all, I really like that book. I
Speaker 1: recommend everyone he read it. I had a lot of
Speaker 1: fun reading it, and I actually chatted with him on
Speaker 1: the previous podcast about it, so folks can check that out.
Speaker 1: But I think that that line of argument is a
Speaker 1: little dangerous. You know, it's sort of like post factor rationalization.
Speaker 1: It's like saying, like it's easy to convince yourself that
Speaker 1: humans are a natural endpoint to evolution, like well boy,
Speaker 1: bipedalism makes a lot of sense. Having two eyes makes
Speaker 1: a lot of sense. It makes sense to have a
Speaker 1: nose on your face, and you could get yourself towards
Speaker 1: arguing like, yeah, aliens are going to look a lot
Speaker 1: like humans because we make sense. But what we don't
Speaker 1: know is how many other ways evolution could have gone
Speaker 1: right and arrives at other solutions that those folks would
Speaker 1: also say, gosh, it just makes sense to have a
Speaker 1: hand sticking out of your forehead, you know, or to
Speaker 1: have a transient aus or whatever. Fun you could rationalize
Speaker 1: those things. It's sort of like counting coincidences, right, We're
Speaker 1: not good at thinking about the breadth of possibilities. And specifically,
Speaker 1: I think that our evolution a lot of the arguments
Speaker 1: that he makes, you know, like critters will eat other critters,
Speaker 1: precise predation is universal, depend on the environment that we've
Speaker 1: evolved in, you know, and some of the sort of
Speaker 1: fundamental economics of it, like imagine if instead of critters
Speaker 1: walking across a surface of a planet or even swimming
Speaker 1: in its ocean, and what if we were life forms
Speaker 1: that existed in the atmosphere of a star, right, we
Speaker 1: were like currents of plasma and the distinction between alien
Speaker 1: bodies wasn't even that crisp, right. I think about where
Speaker 1: you define the edge of your body. Is it at
Speaker 1: your skin? No, because it's hair there. Okay, your hair's
Speaker 1: But now you have like a weird fuzzy definition for
Speaker 1: like where it's Kelly and where it's not Kelly. And
Speaker 1: if you dig down and you're like really philosophical about it,
Speaker 1: it's not well defined. Like there's a fuzzy edge between
Speaker 1: Kelly and the universe. And we like to think of
Speaker 1: ourselves as a thing, a one thing that's distinct from
Speaker 1: the universe because it's important to us sort of like
Speaker 1: culturally and mentally. But what if we weren't you know,
Speaker 1: if we were like flowed between each other and we
Speaker 1: like shared plasma or whatever, we would have a very
Speaker 1: different sort of relationship with the idea of identity, and
Speaker 1: that could change fundamentally what it's like to be a
Speaker 1: critter in that kind of you know, evolutionary economics, that's
Speaker 1: just one example, you know, or in that and if
Speaker 1: we evolved in a very different kind of situation, like
Speaker 1: a subsurface ocean. You know, we think that there might
Speaker 1: be oceans even in our solar system, under thick layers
Speaker 1: of ice, and so if you're some sort of like
Speaker 1: weird critter that flips around a completely dark ocean, you
Speaker 1: might evolve, and then you might have no interest in
Speaker 1: the outer universe because you don't even know that it's there,
Speaker 1: and maybe you don't develop thumbs or technology or do
Speaker 1: anything interesting like that. And so there's lots of situations
Speaker 1: where aliens are just weirder than I think zoologists mighte.
Speaker 2: I don't know why you need to, you know, hone
Speaker 2: in on my people, but all right, I see your point,
Speaker 2: and I think that your imagination is why I enjoyed
Speaker 2: your science fiction so much.
Speaker 1: Thank you. I think the lesson here is that there
Speaker 1: are a lot of human patterns that we don't recognize
Speaker 1: our human patterns, and the best thing about meeting aliens
Speaker 1: will be discovering those things, will be understanding Oh my gosh,
Speaker 1: we never even imagined that you didn't have to have X,
Speaker 1: Y or Z for life, and would tell you what X,
Speaker 1: Y and Z were if I knew now, But I
Speaker 1: don't write, And so that's one of the reasons I
Speaker 1: had so much fun writing that book. Is like thinking
Speaker 1: about the edges of our knowledge and where we might
Speaker 1: be making assumptions if we hadn't realized. And frankly, I
Speaker 1: think biologists are way ahead of physicists in this regard.
Speaker 1: You know, y'all have thought about like, hey, do we
Speaker 1: need water for life? It might be possible to use ammonia.
Speaker 1: Do we need carbon for our chemistry? No, you could
Speaker 1: actually maybe use silicon. And that's been helpful because it's
Speaker 1: changed the way we look for life and imagine where
Speaker 1: it is. I think physicists are well behind because they
Speaker 1: all just assume that aliens will do physics the way
Speaker 1: that we do, and that's probably wrong.
Speaker 2: On behalf of my community. I thank you for the compliments.
Speaker 2: All right, let's see what Julie thinks of your answer,
Speaker 2: And thank you to Julie for giving me the opportunity
Speaker 2: to talk about how great Daniel's book is. Hi, thanks
Speaker 2: for answering my question.
Speaker 4: I really like what you said about how the Milky
Speaker 4: Way isn't that big compared to its age, and there
Speaker 4: would maybe be relics out there that in theory we'd
Speaker 4: be able to detect. I was kind of just thinking
Speaker 4: about how big the universe is without necessarily factoring in
Speaker 4: how old it is too, so I think I'm overall
Speaker 4: back on team Paradox. But the explanation for the paradox
Speaker 4: could be many, many different things beyond just how far
Speaker 4: apart everything is, like all of the many different factors
Speaker 4: that you mentioned, and just how truly alien they could be.
Speaker 4: I think it's so fun to think about this stuff.
Speaker 4: So really enjoyed how you talked through it. Thanks again, Well,
Speaker 4: love the show.
Speaker 2: All right, So next up we have a question from
Speaker 2: our Discord channel, and if you want to join us
Speaker 2: on Discord, and I really hope that you will, you
Speaker 2: just go to our website at Danielandkelly dot org and
Speaker 2: you can click the link to find our Discord group.
Speaker 2: And today's question is from Pip Darcat on what.
Speaker 1: Do you do the day Kelly when somebody has a
Speaker 1: Discord handle that's not safe for podcasting?
Speaker 2: Ooh, I will ask our amazing audio engineer Matt Kesselman
Speaker 2: to bleep it for me. No promises, I already have
Speaker 2: a plan. Hey, they're extraordinaries. It turns out that listener
Speaker 2: Pip Darcat from Discord wasn't able to get back to
Speaker 2: us in time for putting the audio together for this episode.
Speaker 2: So I'm gonna go ahead and read her question from
Speaker 2: the discord. Hi, Daniel and Kelly, I want to know
Speaker 2: more about suk an ARCHAOM. I was reading a feed
Speaker 2: about how this organism is a missing link between life
Speaker 2: and not life. Would you consider this for an episode, Kelly, Well,
Speaker 2: Pip Darkat indeed, I would. Here's your answer. Hope you're
Speaker 2: doing well?
Speaker 1: All right, So tell me about this question. And how
Speaker 1: do we pronounce the name of this critter?
Speaker 2: Oh, come on, man, you know I don't know the
Speaker 2: answer to that. You know that I am notoriously bad
Speaker 2: at pronouncing all of these names. So I'm gonna say
Speaker 2: it's su sukan archaeom.
Speaker 1: Nice. That sounds plausible.
Speaker 2: Because I said it fast. Yeah, that's why that was
Speaker 2: the trick. And so let's see, I'll jump ahead to
Speaker 2: why it's named that. So in Japanese mythology, there is
Speaker 2: a deity who is small and the name is Sukana.
Speaker 1: Oh.
Speaker 2: Sorry, the deity's full name is Sukana Bikona. My apologies
Speaker 2: to all of Japanese culture. And so they took the
Speaker 2: first part of that deities name. And because this critter
Speaker 2: is exceedingly small, in fact, we haven't even seen it
Speaker 2: with our eyes yet. We've only found its genome and
Speaker 2: sequenced it so far. They put that name in front,
Speaker 2: and then since it appears to be from the domain Arkaia,
Speaker 2: they named it's kind of Arkao very cool, which rolls
Speaker 2: off the tongue. Whether it's correct or not. I like it.
Speaker 1: Ar KaiA is really fascinating. Tell us a little bit
Speaker 1: about arkae. I think a lot of people don't even
Speaker 1: know that it exists. What is Arkaia and why is
Speaker 1: it so weird and different?
Speaker 2: Yeah? So's it's incredible. And you know, I actually wonder
Speaker 2: if you know more about this from dinner table conversations
Speaker 2: with Katrina, so feel free to jump in.
Speaker 1: We do have the Tree of Life run in front
Speaker 1: of our dining room table, so Arkia does come up sometimes.
Speaker 2: Do you do you have like a painting of the
Speaker 2: Tree of Life in your kitchen?
Speaker 1: We have a big poster of it.
Speaker 2: Yeah, oh that's amazing. I need that. And you know
Speaker 2: what I learned in this episode is that you won't
Speaker 2: find viruses on that tree.
Speaker 1: Yeah that's true, which.
Speaker 2: Kind of makes sense but also kind of yeah, makes
Speaker 2: me think of some evolutionary questions. But anyway, okay, way
Speaker 2: back in our evolutionary history, so very close to the
Speaker 2: base of that tree, you ended up getting three different domains.
Speaker 2: So you ended up with three splits, and so you
Speaker 2: get ar KaiA, bacteria and ukryota. Ukryota have membrane bound organelles,
Speaker 2: so we are eukaryotes. We have these membrane bound organelles.
Speaker 2: We call them organadoes in a past episode, and I
Speaker 2: thought that was cute, and I'll never forget.
Speaker 1: I think it's amazing that u caryotes basically have like
Speaker 1: a little clump of ocean, right, Like, yeah, we think
Speaker 1: life started in the ocean, and we came out of
Speaker 1: the ocean, but we brought with us basically the ocean.
Speaker 1: We're basically little walking bags of ocean. It's sort of incredible.
Speaker 2: It is amazing. Yeah, And so these three different domains
Speaker 2: differ in things like what makes up their cellular wall,
Speaker 2: how they structure their genes. For example, bacteria and Arcaea
Speaker 2: tend to have circular chromosomes, and eukaryotes tend to have
Speaker 2: linear chromosomes.
Speaker 1: So eukaryots are distinguished because they have a nucleus. How
Speaker 1: do you tell the difference between prokaryots and arcaea.
Speaker 2: Yeah, so prokaryote is a phrase that just refers to
Speaker 2: organisms that don't have membrane bound organelles, as I understand it,
Speaker 2: and I think that because we've created this distinction, people
Speaker 2: often think that arka and bacteria are closely related because
Speaker 2: they're both prokaryotes. But as I understand it, arka, bacteria,
Speaker 2: and eukaryota are all pretty like similarly distant, Like arka
Speaker 2: aren't that much closer to bacteria than they would be
Speaker 2: to us?
Speaker 1: All right, I feel like you trying to understand the
Speaker 1: difference between leptons and hadrons and masons and stuff. So
Speaker 1: we have eukaryotes, which are on the side, then we
Speaker 1: have prokaryotes, and within prokaryotes we have bacteria, and we
Speaker 1: have arkaa. Is that right?
Speaker 2: I think? So I did not prepare that ahead of time.
Speaker 2: I'm trying to pull this out of Kelly intro biobrain,
Speaker 2: but I never had to teach intro bios so it
Speaker 2: never solidified.
Speaker 1: So then why are arkaa thing? How are they different
Speaker 1: from bacteria?
Speaker 2: So they're different in that they have like different kinds
Speaker 2: of cell walls, they have a different way of initiating
Speaker 2: protein synthesis. I think they differ in the way that
Speaker 2: they translate and transcribe their chromosomes, so they differ in
Speaker 2: the way that they sort of read and turn into proteins.
Speaker 2: The information that's in there genetic sequences, and those are
Speaker 2: the notes that I have written down.
Speaker 1: And so tell us about viruses. Why are they not
Speaker 1: in the tree? Are they not alive? How do you
Speaker 1: define life all this stuff?
Speaker 2: There's a number of different criteria depending on who you
Speaker 2: talk to, Some of them will have different definitions than others.
Speaker 2: But two important features that tend to pop up in
Speaker 2: a lot of the definitions is that in order to
Speaker 2: be alive, you need to be able to do some
Speaker 2: of your own metabolism, some of your own metabolic processes.
Speaker 2: So you need to be able to like convert stuff
Speaker 2: into energy that you can use, and you need to
Speaker 2: be able to replicate yourself. And so viruses they don't
Speaker 2: have any metabolic machinery. They just inject themselves into a
Speaker 2: cell and then they hijack the cell's machinery to create
Speaker 2: more virus particles that then burst out of the cell
Speaker 2: and go off and start that process again.
Speaker 1: And is there some like philosophical justification for this or
Speaker 1: is this just an arbitrary dotted line the human draw
Speaker 1: between a big continuum of biological activity.
Speaker 2: I think it might be. What do I think?
Speaker 1: Is this like planets and dwarf planets all over again?
Speaker 2: Yeah, So I was wondering that while I was working
Speaker 2: on this outline, and that's what kind of made me
Speaker 2: go to the Tree of life. And I think part
Speaker 2: of why we can't really fit them on the Tree
Speaker 2: of life is that they just sort of don't fit
Speaker 2: anywhere on there neatly. And I wonder if because we
Speaker 2: couldn't neatly fit them on there anywhere, we're like, all right, well,
Speaker 2: you don't do these other things that are important, and
Speaker 2: if you were doing those things, you'd have more genetic
Speaker 2: information and we could use that to help fit you
Speaker 2: into the tree of life because we could see, like,
Speaker 2: you know, what the blueprints were and how that fit
Speaker 2: onto the tree. But you don't have that. And so
Speaker 2: I wonder if part of it is just like, well,
Speaker 2: we don't know where to put them on the tree
Speaker 2: of life, so we're just gonna say they're not alive.
Speaker 2: And I've met a bunch of the people who come problem.
Speaker 2: It's solved. But and I'm sure a lot of people
Speaker 2: who come up with these definitions are going to be like,
Speaker 2: that is a stupid answer. These are it's very important
Speaker 2: to be able to, like, you know, make your own
Speaker 2: energy and reproduce, and they don't do it, so they
Speaker 2: they are not as good as us in some way.
Speaker 1: All right, Well, if you have strong opinions about the
Speaker 1: definition of life and whether viruses are alive or not,
Speaker 1: right to us with a strongly worded email. We would
Speaker 1: love to hear from you.
Speaker 2: Yeah, no, I would. I think it would be fun
Speaker 2: to have a battle about the different definitions of life
Speaker 2: and not a battle, a conversation, a genial conversation.
Speaker 1: And I love when these mysteries have the context, you know.
Speaker 1: I think it's really cool. Then when we look at planets,
Speaker 1: we also see other stuff that's almost a planet. It
Speaker 1: helps us understand like where it sits in the bigger question.
Speaker 1: And I love you know that there are other great
Speaker 1: apes that are still around, Like I wish there were
Speaker 1: more species of humans that survive to today because it
Speaker 1: would tell us so much more about our evolution and
Speaker 1: our context. And so I think it's really cool that
Speaker 1: we have not just life and inert stuff. We have
Speaker 1: this like weird stuff on the boundary that helps us
Speaker 1: understand like what life means. So that's very cool.
Speaker 2: And so you might be wondering, why did we talk
Speaker 2: about what arkaa are and then why are we talking
Speaker 2: about if viruses are alive or not? And the answer
Speaker 2: is that this there was a finding recently of a
Speaker 2: new species of arkaa. Does Katrina pronounce it arkaa or
Speaker 2: am i oka?
Speaker 1: Yes?
Speaker 2: Great, okay, because if Katrina does it, then I'm doing
Speaker 2: it right. So anyway, so there was a new species
Speaker 2: of Archaea that was discovered and it has a very
Speaker 2: small genome and doesn't seem to do a lot of metabolizing.
Speaker 2: And so there was this idea that went around the
Speaker 2: popular press that maybe this is like a transition between
Speaker 2: things that are alive and not alive, because there's this
Speaker 2: critical feature of being alive that is missing from this species.
Speaker 2: So more of the fuzzy context, more fuzzy context. So
Speaker 2: let me tell you a little bit more about this discovery.
Speaker 2: So they were looking in dino flagelets, which are these
Speaker 2: single celled eukaryotes. You find a lot of them in
Speaker 2: the ocean. They tend to have like these two flagellum
Speaker 2: which are like long, stringy things that they sort of
Speaker 2: move around to help them get from one place to another.
Speaker 2: And one of the things that's interesting about them is
Speaker 2: that they produce bioluminescence, which you can see in the
Speaker 2: ocean and creedy. Oh my gosh. Once I jumped into
Speaker 2: the ocean when the bioluminescing organisms were in there and
Speaker 2: there was this like amazing blue light that just kind
Speaker 2: of like, oh, it was one of the coolest experiences orthing.
Speaker 2: This was in Maine and northern Maine. Yeah, I was
Speaker 2: at a science conference. It's pretty sweet being a scientist sometimes.
Speaker 2: So anyway, dinoflagelets they do that, but the scientists were
Speaker 2: not interested in that. They were interested in the fact
Speaker 2: that the dinoflagelet that they were looking at was thought
Speaker 2: to have a symbiotic critter living inside of it, and
Speaker 2: so they were trying to understand that symbiosis and how
Speaker 2: this it was a cyanobacteria, might be benefiting the dinoflagelet
Speaker 2: and will and so they essentially opened up the dinoflagellate,
Speaker 2: sorry dude, and they sequenced the stuff that was inside
Speaker 2: and when they sequenced the stuff that was inside, they
Speaker 2: found an additional circular DNA sequence that they weren't expecting
Speaker 2: to see, and they did a bunch of extra studies
Speaker 2: to look at it and try to convince themselves that
Speaker 2: they hadn't messed something up, because what was surprising about
Speaker 2: it was that it was so stink and small. The
Speaker 2: circular DNA was so small that it was about five
Speaker 2: percent the length of a genome you'd find in something
Speaker 2: like Ischeria coali or Ecoli, so like very common bacteria.
Speaker 2: And again they thought it was a mistake, but they
Speaker 2: kept sequencing it, and then they assembled it. And when
Speaker 2: you assemble it, what you essentially do is you look
Speaker 2: at the genetic sequences and say, okay, do these sequences
Speaker 2: match up with anything we see anywhere else in the
Speaker 2: tree of life where we know what it does. So
Speaker 2: trying to get a handle on, like what might bese
Speaker 2: sequences do based on what we know happens in other organisms.
Speaker 2: It was about two hundred and thirty ish KILLO base pairs,
Speaker 2: where kilo means like a thousand, right, Daniel, mm hmmm, yeah,
Speaker 2: I always double check these things. So super tiny, and
Speaker 2: so once they convinced themselves that they weren't messing up something.
Speaker 2: They put it on the tree of life and they
Speaker 2: were like, Okay, this appears to be arkaa. It looks
Speaker 2: like it's a whole different phylum of Arka that we
Speaker 2: haven't seen before. And then they went through and they
Speaker 2: looked at what was in the genome and they're like, okay,
Speaker 2: based on what we know about other organisms, what do
Speaker 2: these genome components do?
Speaker 1: So let me back up and ask you a question.
Speaker 1: Just make sure I understand, because my understanding is when
Speaker 1: you sequence something, you don't just like pull the whole
Speaker 1: dema out of the nucleus and read the whole thing.
Speaker 1: You do this process. You basically like shred the cell,
Speaker 1: chop up the DNA in a bunch of short bits.
Speaker 1: You sequence all the short bits like shotgun sequencing, and
Speaker 1: then you use computer programs to like sew it back together.
Speaker 1: And this is like Craig Benter's big innovation decades ago
Speaker 1: that made the human geno much faster. And so then
Speaker 1: you have this mystery sometimes of like, well where do
Speaker 1: these pieces all go together? And I think what you're
Speaker 1: saying is that when they were putting the puzzle together,
Speaker 1: they realized, oh, we're solving two different puzzles here. This
Speaker 1: is not one big puzzle. It's like if you started
Speaker 1: working on a jigsaw puzzle and you noticed, like, oh,
Speaker 1: there's lots of weird blue pieces that don't fit into
Speaker 1: the puzzle, but they do fit with themselves over here
Speaker 1: in the corner. Is that what happened?
Speaker 2: Yeah, that's an incredible explanation actually, And so they didn't
Speaker 2: just find two critters. They actually found more than two
Speaker 2: critters in there. And so they put multiple puzzles together,
Speaker 2: and a lot of the other puzzles they were like, Okay,
Speaker 2: we've seen these puzzles before. But then then when they
Speaker 2: found Sukuna arcam, they were like, what the heck is this?
Speaker 2: They didn't trust that it was anything I see. But
Speaker 2: once they convinced themselves that it was real and they
Speaker 2: hadn't like made some mistake through the part of the process,
Speaker 2: they discovered that it appears to be a whole new
Speaker 2: phylum of Archaea. And then they went through and there
Speaker 2: are a bunch of public databases where people are like
Speaker 2: they collect genetic information and then they put it online.
Speaker 2: And when they started searching through that, they found a
Speaker 2: lot of other sequences that were looked kind of like this,
Speaker 2: and so they think that this is the first example
Speaker 2: in the filum that's been described, but that there's probably
Speaker 2: a bunch of other stuff out there that we've sort
Speaker 2: of seen but not recognized yet.
Speaker 1: All right, And so what makes this one different from
Speaker 1: other archaea? What makes it have its own thylum and
Speaker 1: makes it, you know, whip through the popular press and
Speaker 1: get an article in science.
Speaker 2: So what was particularly exciting was that when they tried
Speaker 2: to figure out what the few genes that were there did,
Speaker 2: most of them were associated with replicating the organism so
Speaker 2: it could do its own reproduction. But there were very few,
Speaker 2: if any genes associated with matisabolism, and so it looks
Speaker 2: like it's somewhere between alive and not alive. So I mentioned,
Speaker 2: you know, the definition of being alive, you've got to
Speaker 2: be able to do your own metabolism and your own reproduction.
Speaker 2: This doesn't seem to be doing its own metabolism, so
Speaker 2: it's probably a parasite of some sort, but it can
Speaker 2: do its own reproduction.
Speaker 1: So it can't do its own metabolism because even a
Speaker 1: parasite like you know, something inside of you that's drinking
Speaker 1: your blood, it's still metabolizing the blood and like feeding
Speaker 1: its own internal chemistry. So what does it mean to
Speaker 1: not be able to do your own metabolism? Does it
Speaker 1: mean that like you're just stealing directly the chemical products
Speaker 1: that store the energy.
Speaker 2: I think, so I don't actually understand how you could
Speaker 2: not metabolic I mean, I guess in the same way
Speaker 2: viruses don't metabolize things. They just hijack machinery. I suspect
Speaker 2: that's what's happening here.
Speaker 1: I see, Yeah, fascinating.
Speaker 2: Yeah, And so most of the paper is like scientific details,
Speaker 2: but at the very end the authors say something to
Speaker 2: the effect of, like, maybe this is like an intermediate step,
Speaker 2: and like this could tell us something about how organisms
Speaker 2: go down the path to becoming a virus. Maybe you
Speaker 2: lose a bunch of stuff as you go and you
Speaker 2: end up with these very like shortened genomes. And not
Speaker 2: everybody was convinced.
Speaker 1: It's like a company that's deciding, hey, we don't need
Speaker 1: to have our own HR department, let's just outsource it
Speaker 1: to some startup or AI or.
Speaker 2: Something, and then they become parasites.
Speaker 1: Wow, that was a quick step to criticizing corporate culture.
Speaker 1: Wasn't it.
Speaker 2: Yes, that's right, But that's.
Speaker 1: Fascinating to suggest that viruses used to be more fully
Speaker 1: alive and have sort of lost this capacity or optimized
Speaker 1: themselves so they realized they didn't need it. That's fascinating.
Speaker 2: Yeah, it's an interesting idea. I don't know if it's
Speaker 2: an idea that's been presented elsewhere, and this was just
Speaker 2: an example that really illustrated that that idea might have
Speaker 2: some legs. But you know, not everyone was convinced. So
Speaker 2: I read this paper in Science that was summarizing. So
Speaker 2: I should also mention that the paper we're talking about,
Speaker 2: the results are on bio archives, so they haven't gone
Speaker 2: through peer review yet, but they're publicly available. But people
Speaker 2: got immediately excited when it went on bioarchive, and Science
Speaker 2: covered it, and Science did some interviews with other people
Speaker 2: and they found a San Diego State University biologist whose
Speaker 2: name is Elizabeth Waters. She wasn't part of this study,
Speaker 2: but she does look at small archaeol parasites, and she
Speaker 2: said that maybe this is a virus in the making.
Speaker 2: She said, this is a bit of a jump. If true, amazing,
Speaker 2: So she's like a little skeptical if it turns out
Speaker 2: that would be super cool. But there are other organisms
Speaker 2: with very small genomes. I think this one is particularly small,
Speaker 2: but it's not necessarily the case that a small genome
Speaker 2: organism is, you know, the missing link between becoming a virus.
Speaker 1: And this is an example of folks of good journalism
Speaker 1: here because they went out and talked to somebody who
Speaker 1: wasn't invested in hyping this result and who knows the details,
Speaker 1: and asked her like, are you impressed by this? And
Speaker 1: she was like, hm, you know, she's holding her fire
Speaker 1: a little bit. And that tells you, like, we're not
Speaker 1: all convinced that this is a big change that you know,
Speaker 1: everybody's now going to update the textbooks or something, but
Speaker 1: it is exciting and promising.
Speaker 2: Yeah, absolutely, And to me this highlights you know, so
Speaker 2: maybe this is a little bit of a self defensive
Speaker 2: statement I'm about to make here. So you know, you've
Speaker 2: said that when physics is doing well, it's doing more
Speaker 2: than just taxonomy. This is essentially just taxonomy. They found
Speaker 2: something new. They were like, well, let's look at this
Speaker 2: new thing, and maybe this is leading to a brand
Speaker 2: new understanding of life or not life, depending on what
Speaker 2: you co virus is, you know, and just how things
Speaker 2: work and understanding our world a little bit better. And
Speaker 2: so I would argue just taxonomy is really important. Thank
Speaker 2: you for this fascinating just taxonomy, and thank you to
Speaker 2: Pip Darcat for this fantastic discord. Question.
Speaker 1: Well, if I could comment, I think that this is
Speaker 1: a fantastic bit of science. But I think it's especially
Speaker 1: interesting because it's not just taxonomy, right. You're not just
Speaker 1: putting it there and saying, well, look, it's just there.
Speaker 1: You're thinking about the consequences, You're drawing analogies, you're asking
Speaker 1: philosophical questions about what it all means. So taxonomy is
Speaker 1: very valuable, partially because it inspires this kind of deeper
Speaker 1: thinking and making these connections. So I would say taxonomy
Speaker 1: is step one in a really fascinating and valuable process.
Speaker 2: Right, But you can't get to step two without step one.
Speaker 2: But i'll give you Yeah, I agreed, Okay, I'll give
Speaker 2: you that.
Speaker 1: Okay, we're back and we're answering questions from listeners. If
Speaker 1: you have a question about the universe you've never really
Speaker 1: had satisfactorily answered, please write to us. We would love
Speaker 1: to give it a shot. You can email us to
Speaker 1: questions at Daniel and Kelly dot org. You can join
Speaker 1: our discord and you can find the link to that
Speaker 1: on our website Daniel and Kelly dot org. We really
Speaker 1: would love to hear from you. So many people write
Speaker 1: in and we respond and then they say, oh, my gosh,
Speaker 1: I can't believe you actually wrote back. Well, we really do.
Speaker 1: You will hear from us. Your message will not just
Speaker 1: be ignored in the black hole of the internet.
Speaker 2: That's right. We can't wait to hear from you, all.
Speaker 1: Right, And so now we have a really fascinating physics
Speaker 1: question from John.
Speaker 5: Hi, Daniel and Kelly. My name is John Chai. My
Speaker 5: question is what would happen if the speed of light
Speaker 5: suddenly changed, like let's say a giant cosmic switch were
Speaker 5: flipped and suddenly the speed of light got cut in half.
Speaker 5: Would it be completely catastrophic for all of existence or
Speaker 5: would it go largely unnoticed because even half of the
Speaker 5: speed of light is still really really fast. Thanks a lot,
Speaker 5: and thanks for the great show.
Speaker 2: Ooh, this is fantastic, And I think this is another
Speaker 2: one of those questions where so you're always encouraging us
Speaker 2: to take what we know and think, you know, if
Speaker 2: we tinkered with it a little bit, how would that,
Speaker 2: you know, break the universe? And essentially, like understanding how
Speaker 2: tinkering with things would change things helps us understand if
Speaker 2: we really understand what's happening. Yeah, and I use the
Speaker 2: word understand a lot because I'm the most articulate person
Speaker 2: on the planet. But you understand where I'm going.
Speaker 1: So yeah, and this actually connects to our earlier conversation
Speaker 1: about the Fermi paradox. You know, another way to imagine
Speaker 1: what aliens might be like that would make them very
Speaker 1: alien is if they lived in a relativistic environment. You know,
Speaker 1: what if they evolved in a situation where they're very
Speaker 1: often going at eight tenths of the speed of light
Speaker 1: relative to each other or relative to their houses or something,
Speaker 1: and so they observe relativity in action as children, and
Speaker 1: they develop an intuition for it, and to them it
Speaker 1: makes perfect sense that moving clocks run slow, and moving
Speaker 1: yardsticks look short and all this kind of stuff. You know,
Speaker 1: if to them, the universe would be very different and
Speaker 1: their path of their science would be very different than ours.
Speaker 1: But here John is asking a different question. Basically, he's
Speaker 1: imagining that he's at the control panel of the universe,
Speaker 1: and he's got in front of him all these fundamental constants,
Speaker 1: because there are these weird numbers in the universe that
Speaker 1: seem to control how physics works. You know, why is
Speaker 1: the weak force week? Why is the strong force strong?
Speaker 1: Why is gravity so weak? Why is the universe this
Speaker 1: big and not that big? Why are you galaxies this
Speaker 1: size and not bigger? How come stars get this size?
Speaker 1: It's like they are all these numbers in physics, and
Speaker 1: some of them seem arbitrary. And so he's wondering if
Speaker 1: he was at the control panel and he cut the
Speaker 1: speed of light from three times ten to eight meters
Speaker 1: per second down to half of that, what would change?
Speaker 1: How would the universe look different? Would we notice? And
Speaker 1: I think part of the motivation for this question is
Speaker 1: that the speed of light is so fast that it's
Speaker 1: essentially infinite. You don't take into account when you're walking
Speaker 1: down the hallway the fact that the light that's hitting
Speaker 1: your eyeballs is a little bit out of date, and
Speaker 1: the person walking in the other direction is not actually
Speaker 1: where they appear to be there slightly ahead of it
Speaker 1: because the light has taken some time to reach your eye.
Speaker 1: We treat it as instantaneous. So I think he's wondering
Speaker 1: what life would be like, what the universe would be
Speaker 1: like if it wasn't so instantaneous. If we sense that delay,
Speaker 1: if the speed of light was slower and like, maybe
Speaker 1: closer to the speed of sound.
Speaker 2: Can I guess so? I feel like, because it's going
Speaker 2: so fast day to day, we wouldn't notice anything, but
Speaker 2: when we were looking out at like stars, we'd have
Speaker 2: to take into account the fact that what we're seeing
Speaker 2: was even farther back in the past. But how am
Speaker 2: I wrong?
Speaker 1: No? I think you're mostly right. But before we dig
Speaker 1: into all those consequences, I have to nerd out for
Speaker 1: a little bit about what it means to change the
Speaker 1: speed of light. I mean, I think if you're standing
Speaker 1: at the control panel of the universe, the speed of
Speaker 1: light is not one of those numbers, one of the
Speaker 1: knobs for determining the nature of physics. I think those
Speaker 1: knobs need to be dimensionless numbers, not things with like
Speaker 1: meters per second in them, and not just because meters
Speaker 1: and seconds are things humans invented, but because the dimensions
Speaker 1: make it connected to so many other constants, like for example,
Speaker 1: you could change the speed of light without noticing anything
Speaker 1: if you also, at the same time accommodated other things,
Speaker 1: like you changed the length of a meter and you
Speaker 1: change the speed of light, we wouldn't even notice and
Speaker 1: be like if you scale up the whole universe and
Speaker 1: you scale up all the rulers, there's no change. You
Speaker 1: can't tell if somebody does that. And so, for example,
Speaker 1: if you change the speed of light, do those other
Speaker 1: constants also change? Like the speed of light can be
Speaker 1: expressed in terms of quantities from electromagnetism, which include things
Speaker 1: like the vacuum permittivity of space. So if you change
Speaker 1: the speed of light, you also change those which change
Speaker 1: you know, how electricity works, or you somehow breaking the
Speaker 1: universe and changing the laws of physics themselves. If you
Speaker 1: change dimensionless constants, you can keep all the laws of
Speaker 1: physics the same, and every time you change those you
Speaker 1: really do get an effect. If you change dimension full constants,
Speaker 1: then it's more complicated and ambiguous exactly how it propagates through.
Speaker 1: But you know, we can make some simplifying assumptions and
Speaker 1: play with it anyway.
Speaker 2: And see the speed of light is a dimension full constant.
Speaker 1: Right yeah, because it's meters per second, right, has two
Speaker 1: dimensions to it, And you're right, of light is super
Speaker 1: duper fast, like the fastest any human has ever traveled
Speaker 1: relative to like a nearby object, you know, on Earth
Speaker 1: is something like point zero zero three seven the speed
Speaker 1: of light wo and you know that's like astronauts in
Speaker 1: the space Shuttle orbiting the Earth. Right, And so we're
Speaker 1: talking about tiny, tiny fractions, which is why we don't
Speaker 1: observe relativistic effects. But you're right. One of the ways
Speaker 1: that we do notice the speed of light is in
Speaker 1: terms of what fraction of the universe we can see.
Speaker 1: We look out into space and we see back to
Speaker 1: the beginning of time, and we can do that because
Speaker 1: light takes time to get to us, because the speed
Speaker 1: of light is not infinite, and so the furthest thing
Speaker 1: we can see is something where the photons were emitted
Speaker 1: at the very beginning of the universe, essentially like three
Speaker 1: hundred and eighty thousand years after the Big Bang, and
Speaker 1: have been flying to us ever since. And the speed
Speaker 1: of light limits how far we can see. So if
Speaker 1: the speed of light was half what it was, we
Speaker 1: would be able to see less of the universe because
Speaker 1: these photons we're seeing now wouldn't have had time to
Speaker 1: get here if the speed of light was half of it.
Speaker 1: So the universe would still be the size that it is,
Speaker 1: but we wouldn't see as much of it.
Speaker 2: And how would that impact our understanding of the universe?
Speaker 2: Do you think?
Speaker 1: Ooh, yeah, that's a really fascinating question. You know, I
Speaker 1: think we would still see a lot of the structures. Obviously,
Speaker 1: we could still see the whole Solar System and the galaxy,
Speaker 1: and the structures of the galaxy like the galactic clusters
Speaker 1: and the nearby galactic clusters. Those are not so far away,
Speaker 1: and we would still see the early universe. It's just
Speaker 1: that photons from the early universe were be coming from
Speaker 1: a closer bit of the early universe than in a
Speaker 1: scenario where the speed of light was faster. So, to
Speaker 1: directly answer your question, I don't think that would make
Speaker 1: a big difference. Right. We would still see the whole
Speaker 1: history of the universe. It's just in a smaller chunk
Speaker 1: of it. But the chunk we're seeing right now is
Speaker 1: really really big. It's big enough that already we can
Speaker 1: see that when you zoom out, mostly the universe is uniform,
Speaker 1: right that there's not a lot of structure at the
Speaker 1: highest level, I mean the solar systems, galaxies and galactic clusters.
Speaker 1: But once you zooma up past that, it's basically just foam.
Speaker 1: You know, there's no real structure anywhere. And so we
Speaker 1: can see enough to get that, which I think is
Speaker 1: the biggest structure in the universe. And so it's big
Speaker 1: enough in the universe is old enough for us to
Speaker 1: glimpse that. But there is a connection there.
Speaker 2: You're just a little bubble in the foam of the
Speaker 2: universe that nobody would notice it start.
Speaker 1: But you know, the structure of the universe also would
Speaker 1: be different if the speed of light was smaller, because
Speaker 1: the speed of light is not just the speed of light,
Speaker 1: it's the speed of information, and it limits the biggest
Speaker 1: structure you can make at any point in the universe,
Speaker 1: Like in order for a structure to form, you have
Speaker 1: to have it interact and communicate. Like even gravity is
Speaker 1: limited by the speed of light, and so there isn't time,
Speaker 1: for example, to form a structure that's bigger than the
Speaker 1: speed of light times the age of the universe. It
Speaker 1: just hasn't had time to like gravitationally assemble. And so
Speaker 1: if the speed of light is slow, that means the
Speaker 1: biggest structure you can have would be smaller in the universe.
Speaker 2: Oh so what is the biggest structure that we have
Speaker 2: what would be in small end by this slower speed
Speaker 2: of light.
Speaker 1: Well, this is actually kind of a current mystery because
Speaker 1: we see structures like the slowan great wall. This is
Speaker 1: like sheets of galactic clusters, which at the highest level
Speaker 1: like the edges of those bubbles in the foam, though
Speaker 1: some of those are bigger than the speed of light
Speaker 1: times the age of the universe. So it's a bit
Speaker 1: of a puzzle like how did that form? Are we
Speaker 1: misinterpreting it something that we didn't understand? You know, one
Speaker 1: of my favorite things about science is that we have
Speaker 1: all these threads that should all tell one story because
Speaker 1: we think there's a thing that's happening in the universe,
Speaker 1: and when they don't, that's a hint that there's something
Speaker 1: we don't understand. And there's so many different ways to
Speaker 1: attack the same question. So that's a current mystery. But yes,
Speaker 1: some of those biggest structures, you know, superclusters of galaxies
Speaker 1: woven together into foams and voids would be smaller. So
Speaker 1: basically like the foam would have smaller bubbles.
Speaker 2: Okay, all right, so we've looked at the very big picture.
Speaker 2: If we go back to Earth, what would be different?
Speaker 2: So like when I turn on the light switch, I
Speaker 2: probably wouldn't it wouldn't be I'm guessing that wouldn't be
Speaker 2: like a noticeable difference in how long it took for
Speaker 2: the room to get right. What about other stuff?
Speaker 1: Yeah, so the speed of light is so fast that
Speaker 1: even half the speed of light is crazy fast, and
Speaker 1: there's no way that you would even notice. But we
Speaker 1: might have been able to measure the speed of light
Speaker 1: a little bit sooner in our history, right, people tried
Speaker 1: to measure the speed of light for decades with all
Speaker 1: sorts of hilarious contraptions with lanterns across mountains, and basically
Speaker 1: there rose like, yeah, it's just too fast. We don't know.
Speaker 1: It's faster than we can measure. So we would have
Speaker 1: figured that out sooner, which might have given us a
Speaker 1: handle on relativity earlier. And so I think in that
Speaker 1: universe we might have figured out physics one hundred or
Speaker 1: two hundred years earlier, which is pretty cool.
Speaker 2: Oh then we wouldn't have had Einstein because what would
Speaker 2: he have done? Probably not thing.
Speaker 1: Somebody else would have been Einstein.
Speaker 2: Okay, all right, all right, but what do you have
Speaker 2: had the same hair? It's the important question.
Speaker 1: Really, That's what it all comes down to. This whole
Speaker 1: production is really just to get us to Einstein's hair.
Speaker 2: That's right, that's right.
Speaker 1: But if you imagine like slowing down the speed of
Speaker 1: light even more so that its effects are visible every day. Like,
Speaker 1: imagine if cars moving along the highways were relativistic, you know,
Speaker 1: if they were moving at like eight tenths of the
Speaker 1: speed of light, you know, because the speed of light
Speaker 1: was crazy slower, then we would have that kind of
Speaker 1: alien intuition. We would notice relativistic effects every day, right,
Speaker 1: Like we would see that cars moving along the highway
Speaker 1: are shrunken, and that you know, the people on airplane
Speaker 1: trips don't age as much, right, And it would really
Speaker 1: change the experience of going Like on a long flight,
Speaker 1: you take that fourteen hour flight to Dubai, it doesn't
Speaker 1: feel like fourteen hours, right, It only feels like ten
Speaker 1: minutes or something. So that's really cool. You don't get
Speaker 1: to watch seven movies but you also get your time back, right, Yeah,
Speaker 1: so that would be really cool, but it would also
Speaker 1: make things really hard, Like it's already challenging for me
Speaker 1: to figure out my calendar with time zones, you know,
Speaker 1: like which time zone are they in? What does that
Speaker 1: mean for me? Like, I don't know why that's so complicated.
Speaker 1: Now imagine that on top of that, you need to
Speaker 1: take into account relativistic effects, so like where's Daniel Binn,
Speaker 1: Where is his clock? How much slower is it? It
Speaker 1: would make coordinating things much more complicated because we'd have
Speaker 1: to give up on the concept of simultaneity. One of
Speaker 1: the weirdest consequences of relativity is the fact that clocks
Speaker 1: are not synchronized, which means you don't all agree on
Speaker 1: the order of events. And mostly on the surface of
Speaker 1: the Earth, we can't notice that because everybody's moving very slowly.
Speaker 1: But if we were moving faster relative to the speed
Speaker 1: of light, that would be a real effect and people
Speaker 1: would disagree about important stuff, and yeah, that could have
Speaker 1: real consequences. It would make life a lot more complicated.
Speaker 2: And just to remind myself, you were talking about if
Speaker 2: it was more than just half the speed of light,
Speaker 2: it would have to be yeah, quite a bit more.
Speaker 1: Okay, yeah, just half The speed of light probably would
Speaker 1: have almost no measurable effect on life on Earth, except
Speaker 1: maybe it would take longer to like download a movie
Speaker 1: from some website in Siberia, because the speed of light
Speaker 1: also influences your download times, right, Like you're downloading data
Speaker 1: from across the Earth. That's a significant difference, and so
Speaker 1: the ping time between your computer and that computer is
Speaker 1: limited by the speed of light because that's the speed
Speaker 1: signals move across the Internet, and so it would take
Speaker 1: a little bit longer. You know. In that case, when
Speaker 1: you're downloading a big movie, the latency is not a
Speaker 1: big effect. But if you're trying to have like a
Speaker 1: conversation in real time with somebody on the other side
Speaker 1: of the Earth, then there could be more lags there.
Speaker 2: Well, I'm glad that the speed of light is what
Speaker 2: it is then, because otherwise it would be hard to
Speaker 2: record this podcast with you.
Speaker 1: Yeah, that's true. And then looking out into the cosmos,
Speaker 1: there would be other changes actually in what we see
Speaker 1: out there. Black Holes would be much more significant. The
Speaker 1: size of the radius of a black hole depends on
Speaker 1: the speed of light. You calculate the short siled radius,
Speaker 1: the point past which things can't escape the gravity of
Speaker 1: a black hole that has a factor in it from
Speaker 1: the speed of light. It goes like one over the
Speaker 1: speed of light is squared, So if you shrink at
Speaker 1: the speed of light, that means a larger event horizon
Speaker 1: for the same mass. Right, So black holes with mass
Speaker 1: in our universe would have a much larger radius in
Speaker 1: this universe where the speed of light is smaller. This
Speaker 1: means they could have like a bigger effect on their galaxies. Right.
Speaker 1: We have black holes at the center of all galaxies
Speaker 1: and they're really massive, but they're not that big, you know,
Speaker 1: they're tiny compared to the size of a galaxy. But
Speaker 1: crank down the speed of light by a big factor
Speaker 1: and they can grow. And so like the centers of
Speaker 1: galaxies could have like gargangcheu in black holes, not more
Speaker 1: massive than the current ones, but just bigger, and that
Speaker 1: could actually help them grow to more massive quantity. So
Speaker 1: it would really change black hole physics a lot if
Speaker 1: you change the speed of light.
Speaker 2: But we probably would not get sucked up by a
Speaker 2: black hole. I guess everything could be different if all
Speaker 2: the black holes were different sizes.
Speaker 1: In the end, you got to make it about yourself. Kelly, Right,
Speaker 1: what is the impact on Kelly's life?
Speaker 2: Have you met people? I'm just asking the question that
Speaker 2: the people are asking themselves.
Speaker 1: You're right, y'all are going to be fine, don't worry.
Speaker 2: Thank you, Daniel.
Speaker 1: All right, well, thank you very much for that question. John.
Speaker 1: Let us know if we scratched your Doppler itch.
Speaker 5: Hi, Daniel and Kelly, thanks a lot for pondering my question.
Speaker 5: And I really enjoyed listening to your speculation on how
Speaker 5: our world might be different if the speed of light
Speaker 5: got cut in half. And I also enjoyed listening to
Speaker 5: you think about what might happen if we took it
Speaker 5: to the extreme and it slowed down to like a
Speaker 5: noticeably slow amount. To be honest, I was hoping for
Speaker 5: some explanation of how change in the speed of light
Speaker 5: might be catastrophic to our existence, but I guess in
Speaker 5: science it really doesn't depend on what you're hoping for.
Speaker 5: Thanks a lot, and thanks for the show.
Speaker 1: All right, Thanks very much everybody who sent in their question. Please, pes,
Speaker 1: please please don't be shy. We really do love hearing
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