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Speaker 1: From twitching leaves to thinking minds, Where does I begin?

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Speaker 1: Is it wiring roots or loops that inspires thinking?

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Speaker 2: Birds have been around for one hundred and fifty million years,

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Speaker 2: but chickens less than half of that. So did chickens

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Speaker 2: come first? Or was it eggs? Go ahead, have a

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Speaker 2: guess it. It was kind of long.

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Speaker 1: These rhymes get better every time. To see the early universe,

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Speaker 1: we need neutrinos or gravitational ways. But how will we

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Speaker 1: know what to look for in all of that particle haze?

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Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's

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Speaker 2: answers will make it right.

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Speaker 1: Welcome to Daniel and Kelly's Extraordinary Universe.

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Speaker 2: Listener Questions, Episode thirty.

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Speaker 3: Hi.

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Speaker 1: I'm Daniel. I'm a particle physicist, and I never get

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Speaker 1: tired of hearing questions from listeners.

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Speaker 2: Hello. I'm Kelly Leadersmith. I study parasites and space, and

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Speaker 2: I also never get tired of your questions. They're always wonderful.

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Speaker 2: And Daniel, I have a question for you. Do you

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Speaker 2: prefer eggs that have been sitting in the refrigerator or

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Speaker 2: eggs that have been sitting on your counter?

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Speaker 1: Oh my gosh, I am not prepared to have an

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Speaker 1: opinion about that. Oh, why do they taste the same?

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Speaker 2: Well, you know, I just kind of they probably taste

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Speaker 2: pretty similar. But I've noticed that there are cultural differences.

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Speaker 2: I think in Europe you're more likely to get eggs

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Speaker 2: that don't need to be refrigerated, and so the differences

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Speaker 2: in the United States. I think we've rinse off our eggs,

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Speaker 2: and once you've rinsed them off, they need to be refrigerated.

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Speaker 2: But if you don't rinse off your eggs, they come

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Speaker 2: out of the chicken with a layer called a bloom,

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Speaker 2: which protects against bacteria and stuff like that. And so

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Speaker 2: you can just leave chickens on your counter for a while.

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Speaker 1: You mean eggs on your counter.

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Speaker 2: We're chickens. Yeah, I wouldn't recommend it, but yes, eggs.

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Speaker 1: Come to Kelly's Deli where chickens roam the counter.

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Speaker 2: Yeah, I bet I probably would not get a very

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Speaker 2: good health rating if we didn't.

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Speaker 1: Then, yeah, well there's something fascinating there that eggs are

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Speaker 1: protected from infection. But we usually rinse things because we

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Speaker 1: want them clean and uninfected. But here rinsing things makes

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Speaker 1: them more vulnerable to infection.

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Speaker 2: Yeah, I feel like in America, we want like ultimate

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Speaker 2: control over everything, and we just feel like we have

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Speaker 2: more control if we've shoved things in the fridge. And also,

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Speaker 2: I suppose every once in a while when an egg

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Speaker 2: comes out, it gets a little poo on it, and

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Speaker 2: so if you can rinse it and then stick it

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Speaker 2: in a fridge, you know, maybe you feel better about

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Speaker 2: it that way.

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Speaker 1: I don't really want any poo on my counter, is

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Speaker 1: the truth.

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Speaker 2: Yeah, yeah, no, I get that. I get that. That

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Speaker 2: is one of the downsides of farm fresh chicken eggs

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Speaker 2: is every once in a while you're like, oh, yes,

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Speaker 2: biology happened here and there is some.

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Speaker 1: Poo and on your counter in your house at home

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Speaker 1: on the science farm, are there unwashed chicken eggs and

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Speaker 1: occasional pooh?

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Speaker 2: There are unwashed chicken eggs? Like, the answer is yes.

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Speaker 2: I was gonna try to figure out a nice way

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Speaker 2: to say it. You know, we've got like brushes to

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Speaker 2: clean them off before you crack them, to make sure

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Speaker 2: that none of that pooh ends up. Please come back

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Speaker 2: to our house and visit.

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Speaker 1: Sure, I will. Well, why don't you rinse them before

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Speaker 1: you crack them, because once you rinse them, they're not

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Speaker 1: protected but there's then there's just moments before you crack them.

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Speaker 2: Oh, we rinse and brush well, I mean, you know,

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Speaker 2: when the poo dries, it's harder to get off, and

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Speaker 2: so it's nice to have a brush, and so yeah,

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Speaker 2: we clean it all off right before we crack it

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Speaker 2: to make sure that, like you know, sometimes when I

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Speaker 2: crack eggs, I get shell in the bowl and we

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Speaker 2: just want to make sure that that's clean, because I'm

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Speaker 2: not so good at cracking eggs.

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Speaker 1: But you are very good at answering questions from listeners.

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Speaker 1: And that's what we're doing today on the podcast. We

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Speaker 1: are hearing from all of you everything that makes you

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Speaker 1: wonder about the universe, all the extraordinary fascinating mysteries about

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Speaker 1: the universe that you want to hear about. And so

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Speaker 1: today we are tackling three fascinating topics from biology to physics,

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Speaker 1: to the origins of the universe to the origins of

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Speaker 1: chickens and eggs.

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Speaker 2: Yes we are, so let's jump right in and hear

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Speaker 2: our question from Jared.

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Speaker 3: Hello. My name is Jared, and I'm a huge fan

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Speaker 3: of you both. I absolutely love your show. My three

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Speaker 3: children enjoyed the podcast. Also, my two preteen sons and

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Speaker 3: Joy Kelly's gross biology explanations, and my six year old

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Speaker 3: daughter likes to fall asleep to Daniel's voice during car rides.

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Speaker 3: My question today is about how we classify and explain

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Speaker 3: the different levels of self awareness in the universe. I've

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Speaker 3: been reading about how across the spectrum from reactivity to sapiens,

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Speaker 3: living systems exhibit increasingly complex forms of awareness, ranging from

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Speaker 3: basic stimulus response to sentience, self awareness, and ultimately sapiens,

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Speaker 3: which I now know is different than santhians. I've been

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Speaker 3: reading about how concepts like metacognition, reflective consciousness, and theory

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Speaker 3: of minds see the mark pivotal transitions along this continuum.

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Speaker 3: But the boundaries we've set up to define and described

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Speaker 3: as kind of spectrum of awareness are still fuzzy to me,

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Speaker 3: and it's led me to having like a ton of

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Speaker 3: smaller questions, like what's the difference between plants and machines

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Speaker 3: in terms of reactivity? Could mammals have moments of sapience

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Speaker 3: or could the boundaries be crossed accidentally temporarily? So I

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Speaker 3: was just hoping, with your distinct scientific advantage points that

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Speaker 3: you could help explain the fundamental physical or biological thresholds

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Speaker 3: that enable these higher levels of awareness to emerge from

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Speaker 3: simpler matter in life. And perhaps even let me know

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Speaker 3: if there are any overlooked mechanisms or principles perhaps at

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Speaker 3: the intersection of physics and biology that would be cool

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Speaker 3: that could help explain not only how these layers of

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Speaker 3: awareness arise, but also the current limits of our scientific

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Speaker 3: understanding of awareness and what might be the next breakthrough

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Speaker 3: that could reshape how we define or recognize it in

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Speaker 3: the universe. All right, thank you very.

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Speaker 1: Much, so thank you Jared number one for sharing the

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Speaker 1: podcast with your kids and helping raise the next generation

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Speaker 1: of curious people in the universe. Awesome, we love that.

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Speaker 1: Thank you so much. And also for asking such a hard,

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Speaker 1: such a deep question about the nature of sentience and

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Speaker 1: consciousness and whether we can understand how that emerges from

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Speaker 1: like core physical activity.

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Speaker 2: And I'd also like to note that I am so

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Speaker 2: glad that the next generation is still excited about gross stuff.

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Speaker 2: So thank you to the preteens for digging the gross biology.

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Speaker 2: But anyway, yes, wow, where do we start with this

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Speaker 2: difficult question? Daniel?

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Speaker 1: Yes, so we got to start by saying we're not

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Speaker 1: going to be offering any solid answers because there are none. Right,

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Speaker 1: we just do not understand this stuff. There are so

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Speaker 1: many issues here, from never being able to probe the

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Speaker 1: awareness of another object in the universe, not to mention

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Speaker 1: another human being right, first person experience this like subjective

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Speaker 1: existence that we have where I feel like I'm in

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Speaker 1: my head and I'm feeling my body. That's not something

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Speaker 1: I can share with you, not something you can probe

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Speaker 1: from the outside, not something you can verify. I don't

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Speaker 1: even know, Kelly, if you are any different fundamentally from

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Speaker 1: a rock in terms of your inner life.

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Speaker 2: Thanks Daniel.

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Speaker 1: I mean I think that you are. You seem different,

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Speaker 1: but I don't know from a philosophical skeptical point of view,

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Speaker 1: and that's fundamentally going to limit us from having any

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Speaker 1: solid answers.

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Speaker 2: Well, I think the good news is that people don't

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Speaker 2: really come to our podcast for solid answers. They come

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Speaker 2: to our podcast for the we don't really know version

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Speaker 2: of answers and so, and.

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Speaker 1: You do that much better than a rock does that.

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Speaker 1: By the way, You're much better podcast host than like

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Speaker 1: a lump of granite.

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Speaker 2: Thanks question Mark.

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Speaker 1: But Jared is asking a really interesting question. About like

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Speaker 1: the spectrum of reactivity, right, Like, how do we categorize

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Speaker 1: these things? How do things get more complicated? Is there

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Speaker 1: a way that we can under stand not just reactivity,

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Speaker 1: but like sentience and conscious experience by gradually scanning up

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Speaker 1: from simple reactivity to the universe all the way up

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Speaker 1: to you know, having a first person experience. So let's

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Speaker 1: take a walk from the simplest to the more complex.

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Speaker 1: We can start with like physical reactivity. Things in the

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Speaker 1: universe react to other things, you know, like if you

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Speaker 1: have a rock out there in the sun, it will

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Speaker 1: absorb photons, it will gain mass, it will change the

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Speaker 1: nature of the chemical bonds, it will store that energy.

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Speaker 1: So that's you know, direct causal reaction to something outside

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Speaker 1: the universe, just like if you press a button on

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Speaker 1: your toaster or you write a program for your computer.

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Speaker 1: The universe seems to be causal. It seems like you

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Speaker 1: can influence the future, and so things that happen in

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Speaker 1: the universe affect the future. Right, that's like the most

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Speaker 1: basic level at which things in the universe interact.

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Speaker 2: Got it, Yes, rocks and Kelly warm up. Let's uh,

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Speaker 2: let's move to more comp.

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Speaker 1: Before we get to more complex though you can already

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Speaker 1: ask does the rock feel anything like the rock is

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Speaker 1: sitting in the sun, it's getting warmed up. Does it

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Speaker 1: go in its own rocky way? Like, mmm, that feels nice,

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Speaker 1: the way like when you have your face in the sun,

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Speaker 1: it feels nice. Obviously, what it's like to be a

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Speaker 1: rock is not going to be what it's like to

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Speaker 1: be Kelly or Daniel or Jared or any of his kids.

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Speaker 1: But there might be something it's like to be that rock,

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Speaker 1: and we can't say that it isn't. And there are

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Speaker 1: even theories out there that everything in the universe is aware,

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Speaker 1: it is conscious at some level, so that by the

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Speaker 1: time we get to podcast host, we can say that

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Speaker 1: that podcast hosts rich inner life, which enjoys poo free eggs,

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Speaker 1: for example, comes emerges from the basic elements of consciousness

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Speaker 1: that begin with fundamental particles. You know that electrons have

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Speaker 1: like a little bit of consciousness and it comes together.

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Speaker 1: I'm not ascribing to that theory. I'm just saying there

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Speaker 1: are people who already, at this level of interaction with

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Speaker 1: the universe put a little dot of awareness and experience.

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Speaker 2: Is there an interesting question to be asked here about,

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Speaker 2: like if you asked AI, and it gave you an

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Speaker 2: answer about its experienced, like because it can answer. Is

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Speaker 2: that an interesting answer?

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Speaker 1: Well, it's interesting because an AI, unlike a rock, can

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Speaker 1: tell you that it has an inner life. Right, if

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Speaker 1: you ask Gemini or chat GPT, they can tell you

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Speaker 1: that they think that they feel that they have thoughts whatever.

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Speaker 1: You can't tell the difference between them having those thoughts

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Speaker 1: and claiming those thoughts, or them not having those thoughts

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Speaker 1: and yet claiming those thoughts, because you could write a

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Speaker 1: program which claims those thoughts and you don't know that

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Speaker 1: it actually has them. Right, Claiming them and having them

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Speaker 1: are different things. And in philosophy we have this concept

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Speaker 1: of a philosophical zombie, and the thought experiment is like, could,

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Speaker 1: for example, there be a version of Kelly who claims

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Speaker 1: to have a rich inner life and acts unless she

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Speaker 1: has a rich inner life, and yet doesn't.

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Speaker 2: You did compare me to a rock earlier.

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Speaker 1: In a flattering, complimentary west You're better than a rock,

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Speaker 1: much much better than thank you. In fact, you rock, Kelly.

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Speaker 1: But the point of that thought experiment, the philosophical zombie,

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Speaker 1: is to point out that the subjective experience we're talking

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Speaker 1: about that inner life is not revealed by your actions.

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Speaker 1: That there's nothing on the exterior you can do to

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Speaker 1: probe it, so that even somebody who seems to have it,

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Speaker 1: even somebody you fall in love with, might not have

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Speaker 1: an interior life. And there are examples of people out

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Speaker 1: there who like fall in love with ch at GPT

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Speaker 1: and have like AI boyfriends and feel real emotions about them,

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Speaker 1: and imagine that the AI also feels real emotions in response,

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Speaker 1: even if it doesn't. So my point is that already

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Speaker 1: at this level, the philosophical questions are complicated.

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Speaker 2: M hm, yes, and I am already sort of feeling

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Speaker 2: existential dreads. So all right, let's move on to the

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Speaker 2: next level.

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Speaker 1: All right, So the next level is like biological. We

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Speaker 1: have simple plants that can do things like organize their cells.

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Speaker 1: They maintain gradients across cell walls. Plants can orient their

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Speaker 1: leaves to the sun. This is more than just like

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Speaker 1: a rock absorbing a photon. There's like a feedback here,

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Speaker 1: there's like memory, you know, there's maybe even goal like behavior.

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Speaker 1: The plants move towards the sun, trees grow up, the

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Speaker 1: roots go down. There's goal like behavior here, but sort

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Speaker 1: of implicit, right, We don't know if the plant is

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Speaker 1: like stretching towards the sun and enjoying having its leaves toasted,

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Speaker 1: but it's definitely more self organized and reactive to the

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Speaker 1: universe than just a rock. And there are some cases

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Speaker 1: that some people tout slime molds for example of you

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Speaker 1: know what seems like maybe intelligent behavior exploring a maze.

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Speaker 1: Though I know, Kelly, that you are not in the

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Speaker 1: top ten list of people who are impressed by slime

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Speaker 1: mold intelligence.

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Speaker 2: Check out one of our earlier Listener Questions episode to

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Speaker 2: hear a Kelly throw cold water on slimbles solved mazes.

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Speaker 1: And you do that even better than a bucket of

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Speaker 1: cold water. I have to.

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Speaker 2: Say, thank you, and maybe better than a rock. And

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Speaker 2: there's all kinds of inanimate objects that I can outperform.

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Speaker 1: All right, So now let's take one more step up

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Speaker 1: the perceptual ladder to critters that have like explicit sensory organs,

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Speaker 1: you know, even simple things like ants and flies. They

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Speaker 1: have eyes, they can experience the world. They have chemical sensors.

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Speaker 1: They communicate with each other, They leave trails for each other,

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Speaker 1: you know, they make sounds, they leave chemicals. They definitely

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Speaker 1: can learn. I have a friend who does experiments on

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Speaker 1: fruit flies, and they definitely can learn sounds and songs

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Speaker 1: and all sorts of stuff. We don't know what it's

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Speaker 1: like to be an ant. There doesn't have to be

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Speaker 1: anything it's like to be an ant or fruitfly. You

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Speaker 1: could have like a little robot which accomplishes exactly the

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Speaker 1: same thing and doesn't have any internal state. But there

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Speaker 1: also could be something it's like to be an ant

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Speaker 1: or a fruit fly. We just don't know.

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Speaker 2: Do you think that there's some chance that we're sort

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Speaker 2: of biasing this towards ourselves by saying, like, oh, they

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Speaker 2: need to have sense organs, like the kinds of sense

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Speaker 2: organs I recognize in myself, you know, because like plants

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Speaker 2: are detecting where the sun is so that they can

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Speaker 2: turn towards it, so they've got something like sense organs.

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Speaker 2: Are we essentially defining oh yeah, things, yeah, to match

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Speaker 2: what we do.

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Speaker 1: Absolutely and obviously, and I don't know that we could

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Speaker 1: do anything else. The only thing we can do is

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Speaker 1: ask about similar experience. Is we can try to think

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Speaker 1: about what it might be like to be something else,

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Speaker 1: But in the end, we're always translating the unfamiliar back

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Speaker 1: into the language of the familiar. You know, this is

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Speaker 1: like a big theme of my book about alien physics

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Speaker 1: is that it's really hard to think outside of your

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Speaker 1: own little box. And so it could be that there's

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Speaker 1: something it's like to be a rock and a plant

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Speaker 1: which is very, very different from what it's like to

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Speaker 1: be human, and it's rich and complicated in a way

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Speaker 1: we just can't underst stand or even conceive of. Even

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Speaker 1: if we could talk to them and they could try

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Speaker 1: to explain it to us, we might never really be

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Speaker 1: able to crock it because there are some things that

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Speaker 1: are just untranslatable.

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Speaker 2: Do aliens speak? Physics available through fine bookstores everywhere.

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Speaker 1: And also terrible bookstores. Yeah, so we've gone from rocks

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Speaker 1: to like plants to now critters with explicit sensory organs.

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Speaker 1: You can take them the next step up and say, well,

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Speaker 1: what about more intelligent animals, Animals that have a model

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Speaker 1: of the world within them. You know that they can

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Speaker 1: integrate sensory information over time, They have memory, they can

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Speaker 1: be trained, they can make predictions. You know, they don't

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Speaker 1: just react to the world and have basic memory. They

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Speaker 1: have like a model of themselves in the world. And

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Speaker 1: they use that to make predictions. That's clearly a more

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Speaker 1: sophisticated way to respond to the world. And in that case,

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Speaker 1: it's tempting to say, look, if you have a mind,

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Speaker 1: and in that mind you have a model of yourself,

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Speaker 1: then clearly referring to yourself. And isn't that a kind

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Speaker 1: of experience. It seems very likely. And you know, when

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Speaker 1: I interact with my dog, it's very easy for me

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Speaker 1: to see parallels in my dog's emotional response to my own,

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Speaker 1: Like he likes being scratched, and I can tell that

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Speaker 1: he likes it, right, Or if I'm upset with him,

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Speaker 1: he knows, and I can tell that he doesn't like

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Speaker 1: when I'm upset with him. All these things, And again,

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Speaker 1: maybe it's just the slice of humanity that is reflected

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Speaker 1: in the dog, but there's definitely some overlap there. Right,

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Speaker 1: whatever it's like to be a dog, there are parts

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Speaker 1: of it that are similar enough to what it's like

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Speaker 1: to be human that we can have that emotional connection, right,

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Speaker 1: And so it's very tempting to say, well, clearly my

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Speaker 1: dog has an inner life. It is something it's like

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Speaker 1: to be Daniel's dog. But again, how do I really

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Speaker 1: know if somebody came along and like magically removed that

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Speaker 1: experience from my dog but kept all the same behavior. Obviously,

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Speaker 1: I couldn't tell by construction. So it's frustratingly opaque.

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Speaker 2: Yeah, it does kind of feel like you were a

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Speaker 2: little bit more will to entertain the idea that your

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Speaker 2: dog has a rich inner life than you were to

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Speaker 2: entertain the idea that your co host has a rich

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Speaker 2: inner life.

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Speaker 1: I'll say, in my defense, I made that argument as

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Speaker 1: an example of ridiculous but unrefutable arguments.

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Speaker 2: Right, I'm just giving you a hard time.

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Speaker 1: Okay, go on, No, but I mean I only have

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Speaker 1: a dog in my house. You have a whole spectrum

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Speaker 1: of critters. Give us a sordid list from most to

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Speaker 1: least likely to have an inner life.

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Speaker 2: Chickens, no inner life.

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Speaker 1: Chickens are just robots, you're saying.

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Speaker 2: Just robots, just robots. And my doggy milo very rich

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Speaker 2: inner life. And my goats, you know, I think my

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Speaker 2: goats are very frustrated when I don't let them out

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Speaker 2: on time or when I come out without animal crackers,

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Speaker 2: and they've got a rich inner life.

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Speaker 1: And then you know, the next step, of course, is

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Speaker 1: full sapience. You know where you can think, you have language,

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Speaker 1: you can have abstract concepts, you can think about thinking,

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Speaker 1: you can argue about it, arguing to have a rich

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Speaker 1: inner life and a model of the world that includes

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Speaker 1: yourself and your own model of the world in it.

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Speaker 1: And it's recursive all the way down. Where along this

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Speaker 1: spectrum does experience emerge, We just don't know, right This

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Speaker 1: is what they call the hard problem of consciousness. Even

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Speaker 1: if you can understand mechanically how the brain works, signals

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Speaker 1: go up the optic nerve dot dot dot, that doesn't

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Speaker 1: tell you why there's something it's like to be a person.

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Speaker 1: And so you know, there's all these various approaches that

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Speaker 1: people take in the philosophical community. We mentioned one of

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Speaker 1: them already, pan psychism, where mentality is a fundamental aspect

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Speaker 1: of reality, like mass or charge. It's not the idea that,

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Speaker 1: like electrons have political opinions, but that there's some sort

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Speaker 1: of minimal experiential properties of all matter at the most

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Speaker 1: basic level, and that the experience doesn't emerge suddenly but

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Speaker 1: gradually from the simple experiences combining into richer experiences of

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Speaker 1: complex systems. That's a not of like widely held or

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Speaker 1: mainstream view, but it is an opinion I've seen out there.

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Speaker 2: I feel like I've sort of lost track of what

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Speaker 2: we mean by experience and mentality at this point, So like,

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Speaker 2: experience must mean more than like a photon has hit

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Speaker 2: me and I have recognized that the photon has hit me,

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Speaker 2: and mentality must be Yeah, Like, what do we mean

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Speaker 2: now by experience and mentality?

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Speaker 1: I mean that there's something it's like to be you. Okay,

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Speaker 1: you know that you're having a first person experience, got it?

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Speaker 2: Okay?

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Speaker 1: And there are people who deny that, right, Folks like

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Speaker 1: Daniel Dennett, a school of thought called reductive physicalism, say

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Speaker 1: there's no first person experience, that there is no moment

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Speaker 1: of Now. What you think you are experiencing right now

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Speaker 1: is just your brain analyzing what recently happened, right that

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Speaker 1: the moment of the present itself is an illusion, and

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Speaker 1: it's constructed by your brain putting together a bunch of

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Speaker 1: sensor reinformation telling a story about what just happened. And

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Speaker 1: it's so recent. You surf along the edge of it

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Speaker 1: and it feels like there's a you, but there isn't really,

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Speaker 1: So you weirdly remember being conscious, but never really are.

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Speaker 1: It's a fascinating idea.

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Speaker 2: Are we in like a simulation or we're just like.

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Speaker 1: No, no, we are not in a simulation. We are

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Speaker 1: just remembering a present we never experienced. This is a

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Speaker 1: fascinating idea and it's hard to wrap your mind around.

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Speaker 1: It's in Daniel Denni's book Consciousness Explained, which is like, wow,

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Speaker 1: ambitious title. Right, Yeah, it's a really fun book and

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Speaker 1: we should dive into it more another time. Another idea

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Speaker 1: is called functionalism. It says, look, it's all about information.

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Speaker 1: It doesn't matter what matter it is. It's not like

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Speaker 1: the sentience is built into the electron and then it

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Speaker 1: all comes together. It's about how this stuff is arranged,

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Speaker 1: and it's about the model in your head of the universe.

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Speaker 1: But there's no real explanation there for like how that emerges,

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Speaker 1: Like where along that spectrum we just described it begins

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Speaker 1: that there's something that's like to be an ant or

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Speaker 1: a bird, just that it comes out of the information.

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Speaker 1: And here the implication is that if you build a

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Speaker 1: simulation of Kelly, it would have the same experience as Kelly.

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Speaker 1: It's nothing about the wet weear or the kellyness of

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Speaker 1: your particles. It's just the arrangements of the stuff.

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Speaker 2: It's arrangement.

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Speaker 1: And then the last sort of broad philosophical approach is

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Speaker 1: called strong emergence, and it says, hey, this whole argument

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Speaker 1: that things need to bubble up from the littlest bits,

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Speaker 1: that somehow the first person experience needs to be emerging

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Speaker 1: from the towing and froing of the little particles inside.

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Speaker 1: You forget all that, even though it seems to be

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Speaker 1: like the foundation of modern science and physics at least,

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Speaker 1: and say, look, things emerge because there are just new

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Speaker 1: fundamental laws at every level. So it's not like the

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Speaker 1: behavior the biggest stuff bubbles up somehow from the behavior

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Speaker 1: of the smallest stuff. It's got its own laws, and

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Speaker 1: maybe things flow the other way. And like consciousness emergence

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Speaker 1: because there's some weird new law of the universe and

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Speaker 1: it can control the microscopic instead of the microscopic controlling

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Speaker 1: the macroscopic. So you know, the short answer is nobody

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Speaker 1: knows the answer, and there's an enormous variety of totally

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Speaker 1: contradictory approaches in the philosophical community to this very very

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Speaker 1: hard problem.

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Speaker 2: I feel like this is the kind of conversation where

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Speaker 2: I need to like, hear a sentence and then sit

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Speaker 2: for ten or fifteen minutes to be like, what did

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Speaker 2: that sentence mean? And then start again.

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Speaker 1: Yeah, yeah, yeah, that's philosophy for you, exactly, and you're

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Speaker 1: going to go all the way down to like what

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Speaker 1: does meaning mean? Anyway?

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Speaker 2: That's right? Am I real? Is this is any of

437
00:22:45,000 --> 00:22:46,359
Speaker 2: this real? What is real?

438
00:22:46,520 --> 00:22:50,240
Speaker 1: Yeah? Exactly, And then you'll discover that at the foundations

439
00:22:50,240 --> 00:22:53,840
Speaker 1: of philosophy you know nothing and we know nothing, and

440
00:22:54,000 --> 00:22:57,000
Speaker 1: you know, that's where de Karte was and it's very

441
00:22:57,000 --> 00:22:59,640
Speaker 1: hard to go anywhere from there. So you just got

442
00:22:59,640 --> 00:23:02,159
Speaker 1: to make some assumptions and move forward as best you

443
00:23:02,240 --> 00:23:04,960
Speaker 1: can because it's not clear what we know and what

444
00:23:04,960 --> 00:23:07,720
Speaker 1: we don't know and what knowing even means. All right,

445
00:23:07,800 --> 00:23:10,200
Speaker 1: So I hope we've confused you enough. Jared. Let us

446
00:23:10,240 --> 00:23:13,280
Speaker 1: know if that helped you at all. And thank you

447
00:23:13,320 --> 00:23:14,320
Speaker 1: again for your question.

448
00:23:14,760 --> 00:23:15,040
Speaker 4: Wow.

449
00:23:15,160 --> 00:23:17,440
Speaker 3: Thank you so much, Daniel and Kelly for the amazing

450
00:23:17,560 --> 00:23:20,080
Speaker 3: and detailed answer. You've certainly given us all a lot

451
00:23:20,119 --> 00:23:23,159
Speaker 3: to think about. We promise our next question won't be

452
00:23:23,200 --> 00:23:26,920
Speaker 3: as difficult next time. We'll keep it simpler. Certainly next

453
00:23:26,920 --> 00:23:29,280
Speaker 3: time when we're talking about our cat oreo and we're

454
00:23:29,320 --> 00:23:31,680
Speaker 3: talking about her learned behavior over time and how she's

455
00:23:31,720 --> 00:23:34,600
Speaker 3: picked up on certain human words. We'll now have a

456
00:23:34,680 --> 00:23:38,919
Speaker 3: more context to kind of discuss that. And yeah, we

457
00:23:38,920 --> 00:23:40,680
Speaker 3: don't have any follow up questions. Just keep up the

458
00:23:40,720 --> 00:23:41,960
Speaker 3: great work. We love the podcast.

459
00:23:43,800 --> 00:23:44,159
Speaker 4: Kelly.

460
00:24:04,600 --> 00:24:08,000
Speaker 1: Okay, we're back and we're answering questions from listeners. And

461
00:24:08,080 --> 00:24:13,040
Speaker 1: today we're tackling deep philosophical questions like do rocks feel pain?

462
00:24:13,480 --> 00:24:16,959
Speaker 1: And also ancient questions like what came first? The chicken

463
00:24:17,280 --> 00:24:17,800
Speaker 1: or the egg?

464
00:24:18,040 --> 00:24:20,240
Speaker 2: And this is a question that people, you know, sometimes

465
00:24:20,320 --> 00:24:25,760
Speaker 2: enjoy having long, deep philosophical questions about. But I love

466
00:24:25,880 --> 00:24:28,480
Speaker 2: runing fun and evolution has a clear answer.

467
00:24:28,640 --> 00:24:29,800
Speaker 1: Oh my gosh. Wow.

468
00:24:30,000 --> 00:24:33,160
Speaker 2: And so let's hear Noah's question and then I'm gonna

469
00:24:33,160 --> 00:24:34,240
Speaker 2: give you a clear answer.

470
00:24:34,440 --> 00:24:37,200
Speaker 4: Nice, Hi, Daniel and Kelly. I would love to hear

471
00:24:37,280 --> 00:24:40,879
Speaker 4: about the evolutionary history of chickens and eggs? Is there

472
00:24:40,920 --> 00:24:42,359
Speaker 4: an answer to which came first?

473
00:24:42,920 --> 00:24:44,520
Speaker 1: You're just going to give a clear answer to make

474
00:24:44,560 --> 00:24:46,600
Speaker 1: me look bad because of my philosophical ramblings.

475
00:24:46,680 --> 00:24:51,480
Speaker 2: Yeah, you should have just said no moving. I'm gonna

476
00:24:51,520 --> 00:24:55,359
Speaker 2: saved us all twenty minutes, Daniel, No, that was fun.

477
00:24:55,560 --> 00:24:59,240
Speaker 1: All right, So great question. Noah Kelly, tell us what

478
00:24:59,359 --> 00:25:02,600
Speaker 1: a science say about the chicken versus egg debate.

479
00:25:02,960 --> 00:25:06,800
Speaker 2: Well, eggs have been around for a really long time, Okay, So,

480
00:25:07,000 --> 00:25:10,280
Speaker 2: like we think of women as having eggs and men

481
00:25:10,320 --> 00:25:11,919
Speaker 2: as having sperm, and so if you think of it

482
00:25:11,960 --> 00:25:14,720
Speaker 2: that way, then eggs have been around for you know,

483
00:25:14,840 --> 00:25:17,399
Speaker 2: since we've had fish and since we've had amphibians and

484
00:25:17,760 --> 00:25:19,960
Speaker 2: millions and millions and millions of years. But I understand

485
00:25:20,000 --> 00:25:21,960
Speaker 2: that that's not actually what we're talking about. We're talking

486
00:25:21,960 --> 00:25:24,600
Speaker 2: about you know, chicken eggs as in like having that

487
00:25:24,640 --> 00:25:27,760
Speaker 2: hard shell. But let's take a few steps back. Okay,

488
00:25:27,800 --> 00:25:30,440
Speaker 2: So initially we had you know, fish swimming around in

489
00:25:30,480 --> 00:25:32,879
Speaker 2: the oceans, and we had amphibians and they were laying

490
00:25:32,920 --> 00:25:36,400
Speaker 2: eggs in water. When you lay eggs in water, you've

491
00:25:36,440 --> 00:25:39,119
Speaker 2: got this sort of perk that you're in this aquatic environment,

492
00:25:39,200 --> 00:25:40,639
Speaker 2: so when you lay your eggs, you don't have to

493
00:25:40,640 --> 00:25:42,639
Speaker 2: worry about them drying out and dying.

494
00:25:42,760 --> 00:25:45,600
Speaker 1: But is that where eggs begin with amphibians in the

495
00:25:45,640 --> 00:25:47,480
Speaker 1: water or are their precursors to that.

496
00:25:47,720 --> 00:25:51,280
Speaker 2: Well, invertebrates like starfish also make eggs. But if we're

497
00:25:51,280 --> 00:25:55,040
Speaker 2: talking about vertebrates, making eggs. Then shark and fish were

498
00:25:55,160 --> 00:25:59,080
Speaker 2: making eggs before the amphibians were. But so when four

499
00:25:59,359 --> 00:26:04,240
Speaker 2: limbed verts like reptiles started leaving the ocean to move

500
00:26:04,240 --> 00:26:07,240
Speaker 2: on land, we started having this problem, which is that, well,

501
00:26:07,280 --> 00:26:09,359
Speaker 2: now that we're out of the water, our eggs are

502
00:26:09,359 --> 00:26:11,840
Speaker 2: gonna start drying out, and so what do we do.

503
00:26:11,960 --> 00:26:16,320
Speaker 2: Our eggs needed to become more complicated, and thus arose

504
00:26:16,760 --> 00:26:19,680
Speaker 2: the amniotes, and that's just kind of a fancy word

505
00:26:19,720 --> 00:26:22,320
Speaker 2: for saying we ended up getting fancier eggs, and so

506
00:26:22,480 --> 00:26:28,440
Speaker 2: amniotes includes birds, reptiles, and mammals, and so amniotes these

507
00:26:28,480 --> 00:26:32,320
Speaker 2: are fancy eggs that have three extra layers. And what

508
00:26:32,400 --> 00:26:36,479
Speaker 2: these three extra layers do is they first they provide

509
00:26:36,480 --> 00:26:39,199
Speaker 2: an extra little fluid filled sack and this is like

510
00:26:39,240 --> 00:26:43,320
Speaker 2: the amnion and essentially encloses the embryo and it's like

511
00:26:43,359 --> 00:26:46,160
Speaker 2: a protective fluid. And so if you are egg were

512
00:26:46,200 --> 00:26:49,000
Speaker 2: to go rolling down a hill, which you probably should,

513
00:26:49,040 --> 00:26:51,120
Speaker 2: try to make sure your egg doesn't do. But if

514
00:26:51,119 --> 00:26:54,199
Speaker 2: it does, it like will protect it against bumps and

515
00:26:54,240 --> 00:26:56,960
Speaker 2: bruises and sort of give it a bit of a

516
00:26:57,040 --> 00:27:00,119
Speaker 2: cushion and it just sort of suspends the embryo, and

517
00:27:00,160 --> 00:27:02,800
Speaker 2: it's almost like you've brought your aquatic environment with you

518
00:27:03,040 --> 00:27:04,600
Speaker 2: by putting it in this like sac.

519
00:27:05,040 --> 00:27:09,080
Speaker 1: It's like we're still stuck on ocean based life and

520
00:27:09,200 --> 00:27:11,280
Speaker 1: all of land based life is like carring around little

521
00:27:11,320 --> 00:27:12,040
Speaker 1: bags of ocean.

522
00:27:12,320 --> 00:27:15,760
Speaker 2: Yes, yes, we are carrying our past with us in

523
00:27:15,800 --> 00:27:17,879
Speaker 2: that sense, which is kind of.

524
00:27:17,880 --> 00:27:20,879
Speaker 1: Cool, which is fascinating because like all of the life

525
00:27:20,920 --> 00:27:23,880
Speaker 1: that we build, like robots, it's all dry. Right, why

526
00:27:23,880 --> 00:27:26,080
Speaker 1: don't we build robots that are based on guie bags.

527
00:27:26,240 --> 00:27:28,680
Speaker 2: Well, you're the computer scientist. My sense is that when

528
00:27:28,680 --> 00:27:31,800
Speaker 2: you start adding water to computers, things don't go real well.

529
00:27:35,359 --> 00:27:37,679
Speaker 1: All right, so we have the amnion. What are the

530
00:27:37,720 --> 00:27:40,040
Speaker 1: other extra layers that the amniotes added?

531
00:27:40,119 --> 00:27:43,000
Speaker 2: All right, so you also have the coreon and the alantois.

532
00:27:43,480 --> 00:27:45,919
Speaker 2: I'm sure that I am mispronouncing those as everyone has

533
00:27:45,920 --> 00:27:49,560
Speaker 2: come to expect it. Anyway, those two layers are helpful

534
00:27:49,600 --> 00:27:51,880
Speaker 2: for gas exchange. So you still need to be able

535
00:27:51,880 --> 00:27:55,679
Speaker 2: to get oxygen into the egg to give that oxygen

536
00:27:55,720 --> 00:27:59,040
Speaker 2: to the embryo inside, and you need to be able

537
00:27:59,080 --> 00:28:01,840
Speaker 2: to manage waste. And so these two layers essentially allow

538
00:28:01,920 --> 00:28:05,520
Speaker 2: for gas exchange, and they contain the waste that's produced

539
00:28:05,560 --> 00:28:08,000
Speaker 2: by the embryo inside.

540
00:28:07,600 --> 00:28:11,600
Speaker 1: Waste related question, huh are the amniotes the first ones

541
00:28:11,880 --> 00:28:14,880
Speaker 1: to accidentally pooh on their eggs? Or did fish do that? Also?

542
00:28:15,200 --> 00:28:21,199
Speaker 2: Oh, let's see. Okay, so that's really great question, Daniel.

543
00:28:22,040 --> 00:28:23,320
Speaker 1: How did you not research that?

544
00:28:23,640 --> 00:28:28,720
Speaker 2: Did I not research that? I have had the experience

545
00:28:29,160 --> 00:28:35,480
Speaker 2: of mixing gammeats from fish, which essentially means you very

546
00:28:35,640 --> 00:28:39,360
Speaker 2: gently run your fingers along their abdomen to get them

547
00:28:39,400 --> 00:28:43,600
Speaker 2: to release eggs or sperm, and they have occasionally released

548
00:28:43,680 --> 00:28:44,560
Speaker 2: waste as well.

549
00:28:44,720 --> 00:28:46,600
Speaker 1: What's the furb you used to describe that?

550
00:28:47,360 --> 00:28:52,200
Speaker 2: Some people call it milking. I wasn't gonna go there, but.

551
00:28:52,800 --> 00:28:55,640
Speaker 1: The way you might, like, you know, milk a bowl.

552
00:28:56,880 --> 00:28:59,760
Speaker 2: Yep, yep, that way, that way.

553
00:29:00,880 --> 00:29:02,640
Speaker 1: The glorious labor of science.

554
00:29:02,800 --> 00:29:08,960
Speaker 2: Yes, so the world of an ecologist and so anyway,

555
00:29:09,200 --> 00:29:13,080
Speaker 2: So yeah, so these extra layers made our eggs more

556
00:29:13,080 --> 00:29:16,080
Speaker 2: complicated and allowed us to come on land. But I

557
00:29:16,080 --> 00:29:19,400
Speaker 2: think the chicken in the egg question isn't about you know,

558
00:29:20,080 --> 00:29:22,880
Speaker 2: this slightly more complicated egg. So you know, for example,

559
00:29:22,880 --> 00:29:26,200
Speaker 2: in humans, we essentially brought a lot of this system

560
00:29:26,280 --> 00:29:28,880
Speaker 2: inside of our bodies, so we have an amniotic sack.

561
00:29:29,240 --> 00:29:31,760
Speaker 2: So we've got this fluid filled sack. We put the

562
00:29:31,800 --> 00:29:35,240
Speaker 2: ocean inside of our bodies, and we allowed gas exchange

563
00:29:35,280 --> 00:29:38,520
Speaker 2: with like our placenta and stuff like that. But birds

564
00:29:38,520 --> 00:29:41,600
Speaker 2: and reptiles they made this system where you can essentially

565
00:29:41,760 --> 00:29:44,200
Speaker 2: have the whole thing outside of the body and you

566
00:29:44,200 --> 00:29:46,080
Speaker 2: can like lay it in a nest.

567
00:29:46,360 --> 00:29:47,840
Speaker 1: Seems like a better plan, doesn't it.

568
00:29:48,040 --> 00:29:52,080
Speaker 2: Yeah, yeah, I mean there's there's some benefits to being

569
00:29:52,120 --> 00:29:54,720
Speaker 2: able to carry the baby around with you all the time.

570
00:29:54,800 --> 00:29:58,560
Speaker 2: You always know where it is. There's there's some definite benefits,

571
00:29:59,120 --> 00:30:03,640
Speaker 2: but it is also a bit difficult, I will admit. Okay.

572
00:30:03,680 --> 00:30:05,800
Speaker 2: But so then the question is when did like bird

573
00:30:05,880 --> 00:30:08,320
Speaker 2: eggs as we come to think of them come about.

574
00:30:08,840 --> 00:30:12,080
Speaker 2: And the answer is that birds evolved during the Jurassic period,

575
00:30:12,160 --> 00:30:15,400
Speaker 2: which was one hundred and fifty million years ago, So

576
00:30:15,440 --> 00:30:18,880
Speaker 2: what we think of as bird eggs arose one hundred

577
00:30:18,920 --> 00:30:22,680
Speaker 2: and fifty million years ago. Amniotic eggs in general are

578
00:30:22,720 --> 00:30:26,920
Speaker 2: three hundred million years old, so older than birds. But

579
00:30:26,960 --> 00:30:29,600
Speaker 2: now the question is when do we get chickens?

580
00:30:29,880 --> 00:30:33,560
Speaker 1: All right, wait, so already eggs came before birds broadly.

581
00:30:33,440 --> 00:30:37,760
Speaker 2: Yes, yeah, eggs, so like reptiles have eggy things. Also,

582
00:30:37,840 --> 00:30:39,320
Speaker 2: they're a little bit different than what you think of

583
00:30:39,320 --> 00:30:42,640
Speaker 2: as a chicken egg, but like amniotic eggs three hundred

584
00:30:42,640 --> 00:30:45,800
Speaker 2: million years old. Birds in general one hundred and fifty

585
00:30:45,840 --> 00:30:49,200
Speaker 2: million years old, but chickens weren't like the first birds.

586
00:30:49,280 --> 00:30:52,880
Speaker 2: Chickens come later, and chickens appear to be about sixty

587
00:30:52,920 --> 00:30:56,240
Speaker 2: six million years old. There's a fossil that appears to

588
00:30:56,280 --> 00:30:59,840
Speaker 2: be the ancestor of chickens and ducks. And they have

589
00:31:00,160 --> 00:31:06,760
Speaker 2: named this fossil wonder chicken. No, yes, no, really, wonder chicken.

590
00:31:07,880 --> 00:31:08,600
Speaker 1: Wonderful name.

591
00:31:08,680 --> 00:31:08,840
Speaker 4: Yeah.

592
00:31:08,840 --> 00:31:11,760
Speaker 2: I wasn't able to find a lot more information. I mean,

593
00:31:11,800 --> 00:31:13,320
Speaker 2: I suppose it could have been they found it in

594
00:31:13,400 --> 00:31:15,800
Speaker 2: like Germany and it was like vondo chicken or like

595
00:31:16,040 --> 00:31:17,320
Speaker 2: don't I don't know the details.

596
00:31:17,760 --> 00:31:19,920
Speaker 1: Was it like six feet tall and eight hundred pounds

597
00:31:19,960 --> 00:31:20,600
Speaker 1: or something.

598
00:31:20,480 --> 00:31:20,880
Speaker 2: I hope.

599
00:31:20,880 --> 00:31:23,800
Speaker 1: So when it walked, the earth shook.

600
00:31:25,720 --> 00:31:29,600
Speaker 2: That's right.

601
00:31:30,840 --> 00:31:32,480
Speaker 1: Here come the wonder chicken.

602
00:31:32,680 --> 00:31:34,760
Speaker 2: That's right, Your dinner this time?

603
00:31:36,880 --> 00:31:38,240
Speaker 1: Netflix, please call us.

604
00:31:38,600 --> 00:31:44,320
Speaker 2: That's right. I'm available to consult. I'll write jokes too,

605
00:31:44,320 --> 00:31:48,240
Speaker 2: but not poems. Don't worry, okay, so, but so, so,

606
00:31:48,280 --> 00:31:49,880
Speaker 2: what we really want to know is like, all right,

607
00:31:49,920 --> 00:31:52,239
Speaker 2: so we've had chickens in the wild, and there are

608
00:31:52,360 --> 00:31:55,400
Speaker 2: wild chickens. So, for example, there are a red jungle

609
00:31:55,480 --> 00:31:58,640
Speaker 2: fowl that you can find in Southeast Asia, like so

610
00:31:58,760 --> 00:32:01,800
Speaker 2: in China and India and stuff like that. And there's

611
00:32:01,840 --> 00:32:05,200
Speaker 2: green jungle fowl and gray jungle fowl and the red

612
00:32:05,280 --> 00:32:07,480
Speaker 2: jungle fowl in particular, if you look up pictures of

613
00:32:07,520 --> 00:32:10,560
Speaker 2: them on like Wikipedia, they look like the kind of

614
00:32:10,640 --> 00:32:13,840
Speaker 2: chicken you'd find in your backyard actually kind of surprisingly.

615
00:32:13,880 --> 00:32:16,240
Speaker 2: They have like the beautiful colors and the you know,

616
00:32:16,280 --> 00:32:18,440
Speaker 2: the males look like any rooster that you would expect

617
00:32:18,480 --> 00:32:20,000
Speaker 2: to see in your backyard.

618
00:32:20,080 --> 00:32:21,480
Speaker 1: They poo on their eggs.

619
00:32:21,160 --> 00:32:25,040
Speaker 2: Probably, I mean, yeah, humans pooh on their babies sometimes too.

620
00:32:25,080 --> 00:32:28,160
Speaker 2: It's like it's a it's a messy process, man. And

621
00:32:28,240 --> 00:32:31,120
Speaker 2: so anyway, all right, so then the question is when

622
00:32:31,360 --> 00:32:35,920
Speaker 2: did we start getting domestic chickens? Uh? And that is

623
00:32:35,960 --> 00:32:39,600
Speaker 2: apparently something that scientists fight about a lot. I've got

624
00:32:39,640 --> 00:32:42,080
Speaker 2: a lot of papers where they were, like, you know,

625
00:32:42,240 --> 00:32:45,080
Speaker 2: arguing about methods and this person was mad at that person.

626
00:32:45,200 --> 00:32:48,600
Speaker 2: And it's so it does look like domestic chickens came

627
00:32:48,680 --> 00:32:52,960
Speaker 2: from red jungle fowl. There may have been some hybridization

628
00:32:53,200 --> 00:32:55,920
Speaker 2: with some other wild chicken species, but mostly it came

629
00:32:55,920 --> 00:33:01,480
Speaker 2: from red jungle fowl somewhere in Asia, maybe ten thousand

630
00:33:01,560 --> 00:33:06,320
Speaker 2: years ago. There's some archaeological evidence, and that archaeological evidence

631
00:33:06,360 --> 00:33:09,760
Speaker 2: tends to be like they found chicken eggs, and it's

632
00:33:09,800 --> 00:33:12,600
Speaker 2: not necessarily clear if the chickens were there because of

633
00:33:12,680 --> 00:33:16,440
Speaker 2: the eggs, or because we were eating the chickens, or

634
00:33:16,520 --> 00:33:19,959
Speaker 2: because there were cock fights, and there could have been

635
00:33:19,960 --> 00:33:21,800
Speaker 2: a lot of different reasons we had chickens around. But

636
00:33:21,840 --> 00:33:24,200
Speaker 2: you do see things like chickens, like you know, beautiful

637
00:33:24,280 --> 00:33:29,440
Speaker 2: roosters on coins in different cultures, and so chickens do

638
00:33:29,520 --> 00:33:31,760
Speaker 2: look like they were important part of our cultures for

639
00:33:31,800 --> 00:33:34,960
Speaker 2: a really long time. There was one study that estimated

640
00:33:35,080 --> 00:33:39,920
Speaker 2: that based on like DNA stuff, maybe chickens have been

641
00:33:39,920 --> 00:33:42,600
Speaker 2: with us for fifty thousand years. We've been like carrying

642
00:33:42,640 --> 00:33:45,920
Speaker 2: them around with us. But anyway, definitely, we are sure

643
00:33:46,080 --> 00:33:49,360
Speaker 2: that the ancient Greeks around six hundred BC, so something

644
00:33:49,400 --> 00:33:51,960
Speaker 2: like two thousand, six hundred years ago, you can see

645
00:33:52,080 --> 00:33:55,920
Speaker 2: chicken imagery in like the Greek pottery, and so we're

646
00:33:55,960 --> 00:33:58,480
Speaker 2: sure that we had chickens at least at that point,

647
00:33:58,640 --> 00:33:59,920
Speaker 2: maybe even much earlier.

648
00:34:00,200 --> 00:34:04,640
Speaker 1: Do you think there's any relationship between domesticating chickens and agriculture?

649
00:34:04,960 --> 00:34:07,800
Speaker 1: And I can understand, like domesticating dogs, when you still

650
00:34:07,840 --> 00:34:10,719
Speaker 1: a hunter gatherer community, you can hunt, you kill, you

651
00:34:10,800 --> 00:34:14,359
Speaker 1: share with the dogs. What about chickens. I mean, I

652
00:34:14,360 --> 00:34:18,080
Speaker 1: always think about feeding chickens grains, But actually, now that

653
00:34:18,120 --> 00:34:20,600
Speaker 1: I think about it, chickens eat anything, don't they. So

654
00:34:20,640 --> 00:34:23,560
Speaker 1: you could have chickens eat your kill also.

655
00:34:23,880 --> 00:34:26,800
Speaker 2: Yeah, so I can see it being much much easier

656
00:34:26,960 --> 00:34:29,319
Speaker 2: to have chickens if you're staying in one place, which

657
00:34:29,320 --> 00:34:31,600
Speaker 2: would be easier if you were in agricultural society. But

658
00:34:31,640 --> 00:34:33,759
Speaker 2: on the other hand, yeah, I mean we feed our

659
00:34:33,840 --> 00:34:35,720
Speaker 2: chickens everything.

660
00:34:35,680 --> 00:34:40,680
Speaker 1: Including chicken, right, yeah, cannibalism for the role.

661
00:34:41,000 --> 00:34:45,520
Speaker 2: Yes, pull out your dKu Bingo card, all right, yeah, Okay,

662
00:34:45,520 --> 00:34:48,960
Speaker 2: So the answer is eggs came first, then came chickens.

663
00:34:49,080 --> 00:34:51,759
Speaker 2: But you can still have fun philosophical debates, just not

664
00:34:51,840 --> 00:34:52,840
Speaker 2: when Kelly's around.

665
00:34:53,520 --> 00:34:56,080
Speaker 1: But I think that's only because you've interpreted the question

666
00:34:56,320 --> 00:34:59,640
Speaker 1: as what came first the chicken or any kind of egg.

667
00:35:00,080 --> 00:35:01,840
Speaker 1: But I think the question is what came first the

668
00:35:01,920 --> 00:35:03,520
Speaker 1: chicken or the chicken egg?

669
00:35:04,120 --> 00:35:09,719
Speaker 2: Oh but but no, because eggs came first, you had

670
00:35:09,760 --> 00:35:10,200
Speaker 2: to have.

671
00:35:11,920 --> 00:35:13,880
Speaker 1: Answer the same.

672
00:35:14,880 --> 00:35:17,680
Speaker 2: The red jungle fowl came first, and at some point

673
00:35:17,760 --> 00:35:21,160
Speaker 2: there was anyway domestication happened, and blah blah blah. So

674
00:35:21,280 --> 00:35:24,120
Speaker 2: let's let's see if Noah has more whimsy in his

675
00:35:24,200 --> 00:35:26,600
Speaker 2: heart than I do, and maybe he will disagree with

676
00:35:26,680 --> 00:35:27,200
Speaker 2: my answer.

677
00:35:28,400 --> 00:35:30,799
Speaker 4: I'm endlessly amazed at how much of the story of

678
00:35:30,880 --> 00:35:34,640
Speaker 4: many millions of years that humans have accumulated previously. I

679
00:35:34,719 --> 00:35:37,080
Speaker 4: kind of assumed that this answer would be neither or

680
00:35:37,160 --> 00:35:40,520
Speaker 4: both just played out in time. But I agree with Kelly.

681
00:35:40,600 --> 00:35:43,399
Speaker 4: Eggs seem like the clear winner here. At least there's

682
00:35:43,400 --> 00:35:47,600
Speaker 4: no shortage of as yet unsolved paradoxes to think about

683
00:35:47,760 --> 00:36:08,240
Speaker 4: many things to both of you, I love the show.

684
00:36:09,680 --> 00:36:13,840
Speaker 2: All right, we are moving from eggs to gravitational waves,

685
00:36:13,840 --> 00:36:15,919
Speaker 2: and next up we have a question from Gerard which

686
00:36:15,920 --> 00:36:18,799
Speaker 2: sounds like a really good setup to a new sci

687
00:36:18,800 --> 00:36:19,400
Speaker 2: fi book.

688
00:36:19,760 --> 00:36:21,880
Speaker 5: I've heard that if we could read gravitational waves from

689
00:36:21,880 --> 00:36:23,719
Speaker 5: the Big Thing, someday we would also be able to

690
00:36:23,760 --> 00:36:26,719
Speaker 5: see further into the past than with light. My question is,

691
00:36:26,800 --> 00:36:29,080
Speaker 5: how would we be able to tell which gravity waves

692
00:36:29,080 --> 00:36:31,959
Speaker 5: are visionated in that very early time and which formed later.

693
00:36:32,680 --> 00:36:36,080
Speaker 5: Is there some analog with lights redshifting. I've also heard

694
00:36:36,160 --> 00:36:38,800
Speaker 5: the same possibility with nutrinos again. Would there be a

695
00:36:38,840 --> 00:36:41,160
Speaker 5: wave of distinguishing early in nutrinos from later?

696
00:36:41,560 --> 00:36:44,360
Speaker 1: All right, thank you very much Gerard for this wonderful question.

697
00:36:44,560 --> 00:36:48,560
Speaker 1: I love digging into the early universe, the cosmic egg.

698
00:36:48,760 --> 00:36:49,360
Speaker 1: If you will.

699
00:36:49,680 --> 00:36:53,239
Speaker 2: Oh, you are so good at making connections. I think

700
00:36:53,280 --> 00:36:55,399
Speaker 2: someone should write a book about aliens that can read

701
00:36:55,440 --> 00:36:58,080
Speaker 2: gravitational waves. Maybe somebody has yes.

702
00:36:58,280 --> 00:37:00,719
Speaker 1: Yes, well, we can read gravitational waves, and we hope

703
00:37:00,880 --> 00:37:03,160
Speaker 1: by doing so we can learn something about the history

704
00:37:03,200 --> 00:37:06,440
Speaker 1: of the universe. So far, most of what we've learned

705
00:37:06,480 --> 00:37:10,719
Speaker 1: about the very, very early universe comes from photons, and

706
00:37:10,840 --> 00:37:14,440
Speaker 1: this is the light, the cosmic microwave background light that

707
00:37:14,520 --> 00:37:17,200
Speaker 1: comes from a moment when the universe was very hot

708
00:37:17,400 --> 00:37:21,239
Speaker 1: and very dense and went from being opaque like the

709
00:37:21,280 --> 00:37:25,000
Speaker 1: center of the sun, to cooling enough that protons captured electrons.

710
00:37:24,960 --> 00:37:28,760
Speaker 1: It became neutral hydrogen, which is transparent like hydrogen gas.

711
00:37:29,280 --> 00:37:32,280
Speaker 1: So photons that were made just before that moment, instead

712
00:37:32,280 --> 00:37:35,799
Speaker 1: of getting absorbed, flew free through the universe and are

713
00:37:35,880 --> 00:37:39,800
Speaker 1: still around. Any light made before that time was immediately

714
00:37:39,840 --> 00:37:43,360
Speaker 1: absorbed just like light made inside the sun is absorbed.

715
00:37:43,719 --> 00:37:46,239
Speaker 1: So the earliest we're used to seeing the universe like

716
00:37:46,400 --> 00:37:49,759
Speaker 1: concrete data from what happened a long time ago is

717
00:37:49,960 --> 00:37:53,040
Speaker 1: thirteen point eight billion years ago plus three hundred and

718
00:37:53,080 --> 00:37:55,680
Speaker 1: eighty thousand years. That's how long it took for the

719
00:37:55,760 --> 00:37:58,839
Speaker 1: universe to cool enough to become transparent, and.

720
00:37:58,840 --> 00:38:02,439
Speaker 2: As far as we can imagine, there is no way

721
00:38:02,480 --> 00:38:05,520
Speaker 2: for light to tell us anything about what happened before

722
00:38:05,600 --> 00:38:06,040
Speaker 2: that point.

723
00:38:06,160 --> 00:38:08,640
Speaker 1: That's right, because none of those photons are still around.

724
00:38:09,200 --> 00:38:10,920
Speaker 1: If they were, we could see them and we could

725
00:38:11,000 --> 00:38:13,799
Speaker 1: learn stuff. They were photons made lots and lots of

726
00:38:13,800 --> 00:38:16,319
Speaker 1: lots of them, but they're not around anymore. They were

727
00:38:16,360 --> 00:38:18,839
Speaker 1: gobbled up by the atoms and the electrons.

728
00:38:19,120 --> 00:38:21,279
Speaker 2: Oh, it's like when your great great grandparents are gone

729
00:38:21,320 --> 00:38:24,320
Speaker 2: and they can't tell you their stories anymore exactly.

730
00:38:24,360 --> 00:38:27,160
Speaker 1: But we would like to dig further, right, and before

731
00:38:27,160 --> 00:38:29,479
Speaker 1: we dig further, just a note on the timeline. We'll

732
00:38:29,480 --> 00:38:32,520
Speaker 1: define a moment, call it T equal zero, the first moment.

733
00:38:32,840 --> 00:38:36,000
Speaker 1: We don't mean that that's the first moment of the universe.

734
00:38:36,520 --> 00:38:39,480
Speaker 1: It's the first moment where our laws of physics apply

735
00:38:39,680 --> 00:38:41,759
Speaker 1: at all, where we can think about this stuff where

736
00:38:41,760 --> 00:38:46,000
Speaker 1: we can hypothesize what might have happened, because quantum mechanics

737
00:38:46,000 --> 00:38:49,040
Speaker 1: and general relativity separate enough that we can just use

738
00:38:49,080 --> 00:38:52,200
Speaker 1: one of them. Before that moment, things were so hot

739
00:38:52,239 --> 00:38:54,480
Speaker 1: and so dense and so nasty we can't even think

740
00:38:54,520 --> 00:38:56,799
Speaker 1: about them. We can't do calculations. We don't have a

741
00:38:56,840 --> 00:38:59,800
Speaker 1: theory to explain it because we don't have quantum gravity,

742
00:39:00,120 --> 00:39:02,280
Speaker 1: So we don't know what happened before T equals zero

743
00:39:02,760 --> 00:39:06,120
Speaker 1: T equals zero, and then forwards we can think about theoretically,

744
00:39:06,400 --> 00:39:08,040
Speaker 1: and the gap there is that we can think from

745
00:39:08,040 --> 00:39:11,040
Speaker 1: T equal zero to three hundred and eighty thousand years afterwards,

746
00:39:11,560 --> 00:39:14,600
Speaker 1: but we can't see yet before three hundred and eighty

747
00:39:14,640 --> 00:39:16,720
Speaker 1: thousand years. Does that make sense?

748
00:39:17,120 --> 00:39:20,040
Speaker 2: Yes? And is gravitational waves going to help us get

749
00:39:20,080 --> 00:39:21,000
Speaker 2: back earlier?

750
00:39:21,480 --> 00:39:25,279
Speaker 1: Yes, exactly, And so Gerard is asking about how we

751
00:39:25,280 --> 00:39:28,279
Speaker 1: can see past that boundary, not with light but with

752
00:39:28,360 --> 00:39:31,000
Speaker 1: other probes, and so he talks about two of them,

753
00:39:31,080 --> 00:39:35,320
Speaker 1: gravitational waves and neutrinos. And the reason you could see

754
00:39:35,360 --> 00:39:39,040
Speaker 1: earlier with gravitational waves and neutritos is that the universe

755
00:39:39,080 --> 00:39:41,840
Speaker 1: was transparent to those earlier, and then it was transparent

756
00:39:41,840 --> 00:39:44,920
Speaker 1: to light like many things in the universe are transparent

757
00:39:44,960 --> 00:39:48,600
Speaker 1: to neutrinos that are not transparent to light, like the Earth.

758
00:39:48,960 --> 00:39:51,200
Speaker 1: Photons will not fly through the Earth. The Earth is

759
00:39:51,200 --> 00:39:54,480
Speaker 1: opaque to photons, but it's transparent to neutrinos. Neutrinos will

760
00:39:54,480 --> 00:39:57,280
Speaker 1: fly right through it. So the fact that the universe

761
00:39:57,360 --> 00:39:59,960
Speaker 1: was opaque to photons for the first three hundred eight

762
00:40:00,200 --> 00:40:03,320
Speaker 1: thousand years doesn't mean it was opaque to neutrinos. In fact,

763
00:40:03,480 --> 00:40:07,640
Speaker 1: it was transparent to neutrinos. The same story applies to

764
00:40:07,680 --> 00:40:12,040
Speaker 1: gravitational waves. Gravitational waves pass through basically everything, and they

765
00:40:12,080 --> 00:40:14,520
Speaker 1: scatter a little bit or they're affected by matter, But

766
00:40:14,640 --> 00:40:18,799
Speaker 1: everything but black holes are transparent to gravitational waves. So

767
00:40:18,800 --> 00:40:21,480
Speaker 1: they're an amazing way to look even earlier than light

768
00:40:21,640 --> 00:40:24,960
Speaker 1: can show us what happened in the early universe. And

769
00:40:25,160 --> 00:40:29,360
Speaker 1: Gerard's excellent question is cool, But aren't there neutrinos and

770
00:40:29,400 --> 00:40:33,200
Speaker 1: gravitational waves everywhere? How could we tell the difference between

771
00:40:33,239 --> 00:40:36,319
Speaker 1: a neutrino that came from the very early universe and

772
00:40:36,400 --> 00:40:38,760
Speaker 1: one that was made eight minutes ago in the sun,

773
00:40:39,200 --> 00:40:42,400
Speaker 1: or gravitational waves that are made from black holes? How

774
00:40:42,400 --> 00:40:45,399
Speaker 1: do we know the difference between those and gravitational waves

775
00:40:45,440 --> 00:40:46,920
Speaker 1: from the very early universe.

776
00:40:47,480 --> 00:40:48,480
Speaker 2: You check their ideas.

777
00:40:51,719 --> 00:40:54,319
Speaker 1: That was a joke, but it's actually basically the answer, right,

778
00:40:57,000 --> 00:40:59,920
Speaker 1: So let's start with neutrinos because they're a little easier.

779
00:41:00,520 --> 00:41:04,520
Speaker 1: Neutrinos decoupled from matter, meaning that they stopped really interacting

780
00:41:04,640 --> 00:41:08,560
Speaker 1: with matter about a second after tea equal zero. So

781
00:41:09,080 --> 00:41:12,440
Speaker 1: neutrinos do interact with matter. If it's very very dense,

782
00:41:12,800 --> 00:41:15,680
Speaker 1: then even neutrinos will interact with it. But it only

783
00:41:15,719 --> 00:41:18,560
Speaker 1: took about a second after that te equal zero moment

784
00:41:18,840 --> 00:41:22,239
Speaker 1: for the universe to become dilute enough for neutrinos to

785
00:41:22,360 --> 00:41:25,520
Speaker 1: just fly through and essentially ignore everything. So for the

786
00:41:25,560 --> 00:41:28,879
Speaker 1: first second, neutrinos were absorbed, but that surface of last

787
00:41:28,920 --> 00:41:34,319
Speaker 1: scattering the cosmic neutrino background comes from one second after

788
00:41:34,360 --> 00:41:37,520
Speaker 1: tequal zero instead of three hundred and eighty thousand years,

789
00:41:37,920 --> 00:41:41,279
Speaker 1: which is amazing. Yeah, and so like wow, we could

790
00:41:41,280 --> 00:41:43,760
Speaker 1: see a lot of stuff we hadn't ever seen before.

791
00:41:44,239 --> 00:41:48,600
Speaker 1: Super fun. Now, the issue is that these neutrinos are

792
00:41:48,760 --> 00:41:52,640
Speaker 1: very very low energy, just like the cosmic microwave background

793
00:41:52,760 --> 00:41:57,480
Speaker 1: light is very very red shifted. These neutrinos have been

794
00:41:57,520 --> 00:42:01,000
Speaker 1: super duper red shifted down to low energy. Like the

795
00:42:01,000 --> 00:42:04,240
Speaker 1: plasma that made the cosmic microwave background light was really

796
00:42:04,280 --> 00:42:06,279
Speaker 1: really hot, and when those photons were made, they were

797
00:42:06,400 --> 00:42:09,839
Speaker 1: very high energy, very short wavelength. But the universe has

798
00:42:09,920 --> 00:42:12,960
Speaker 1: expanded since then, and when it expands, it also expands

799
00:42:13,000 --> 00:42:16,400
Speaker 1: those photons and makes them super duper red, which is

800
00:42:16,400 --> 00:42:19,200
Speaker 1: why it's often said that the CMB light is like

801
00:42:19,480 --> 00:42:22,160
Speaker 1: light from a black body at like three degrees kelvin,

802
00:42:22,480 --> 00:42:25,040
Speaker 1: because you'd have to be that cold now to emit

803
00:42:25,040 --> 00:42:29,520
Speaker 1: photons at that wavelength, and the same things happen to neutrinos.

804
00:42:29,760 --> 00:42:33,080
Speaker 1: Neutrinos from the Sun, for example, are like one to

805
00:42:33,160 --> 00:42:37,600
Speaker 1: ten million electron bolts and energy. Neutrinos from supernova maybe

806
00:42:37,600 --> 00:42:40,719
Speaker 1: twice that down to a few MeV. But the neutrinos

807
00:42:40,760 --> 00:42:44,880
Speaker 1: from the very early universe are very very very low energy,

808
00:42:44,920 --> 00:42:47,960
Speaker 1: which makes them very very challenging to see. Not impossible,

809
00:42:48,360 --> 00:42:50,640
Speaker 1: but it means they're not going to interact as much

810
00:42:50,920 --> 00:42:54,440
Speaker 1: as neutrinos with higher energy. So we have plans to

811
00:42:54,480 --> 00:42:57,080
Speaker 1: see them, and we hope to see them. Current experiments

812
00:42:57,080 --> 00:42:59,719
Speaker 1: that look for dark matter, for example, are very very

813
00:42:59,760 --> 00:43:02,960
Speaker 1: sen to things that go bump in the night and

814
00:43:03,000 --> 00:43:06,840
Speaker 1: they very recently become sensitive enough to see like the

815
00:43:06,960 --> 00:43:10,560
Speaker 1: neutrino background, this neutrino fog that fills the universe, not

816
00:43:10,600 --> 00:43:13,680
Speaker 1: from the early universe yet, but from like everything else

817
00:43:13,680 --> 00:43:16,920
Speaker 1: that's emitting neutrinos. And we hope on one day to

818
00:43:16,960 --> 00:43:20,360
Speaker 1: be sensitive enough to these cosmic neutrino background from the

819
00:43:20,440 --> 00:43:23,520
Speaker 1: very early universe, but not yet, and we'll know that

820
00:43:23,520 --> 00:43:25,680
Speaker 1: they're there because we'll see them at lower energy than

821
00:43:25,719 --> 00:43:27,799
Speaker 1: basically anything else makes neutrinos.

822
00:43:28,160 --> 00:43:30,000
Speaker 2: Am I remembering correctly that you told me it's hard

823
00:43:30,000 --> 00:43:32,560
Speaker 2: to measure neutrino's period, Yes.

824
00:43:32,440 --> 00:43:35,480
Speaker 1: Because they hardly interact. You build a big detector, and

825
00:43:35,520 --> 00:43:37,960
Speaker 1: like one in a trillion or one in a quadrillion

826
00:43:38,000 --> 00:43:40,520
Speaker 1: neutrinos that fly through your detector will interact with it.

827
00:43:40,920 --> 00:43:42,279
Speaker 2: Oh man, Yeah, all right.

828
00:43:42,640 --> 00:43:44,959
Speaker 1: The lower the energy, the more challenging it is. So yeah,

829
00:43:45,000 --> 00:43:45,480
Speaker 1: it's hard.

830
00:43:45,560 --> 00:43:47,719
Speaker 2: It's a good thing. There's so much money for science.

831
00:43:49,840 --> 00:43:53,320
Speaker 1: Now. Gravitational waves are also an excellent source of information

832
00:43:53,360 --> 00:43:56,600
Speaker 1: about the early universe, all for the same reason as neutrinos.

833
00:43:56,680 --> 00:43:59,360
Speaker 1: Neutrinos hardly interact with matter because they only use the

834
00:43:59,360 --> 00:44:02,680
Speaker 1: weak force, which is very, very weak gravitational waves only

835
00:44:02,760 --> 00:44:06,000
Speaker 1: use gravity, which is even weaker than the weak force,

836
00:44:06,440 --> 00:44:09,200
Speaker 1: and so they decouple from everything else in the universe

837
00:44:09,280 --> 00:44:13,399
Speaker 1: almost immediately. Right, So using gravitational waves you can see

838
00:44:13,440 --> 00:44:17,360
Speaker 1: even further back than one second after T equals zero.

839
00:44:17,520 --> 00:44:21,840
Speaker 1: Amazing yes, But again they are also affected by redshift,

840
00:44:21,920 --> 00:44:25,760
Speaker 1: and so these would be very very low frequency gravitational waves,

841
00:44:25,880 --> 00:44:29,680
Speaker 1: very long wavelengths. Now, the gravitational waves that we're used

842
00:44:29,680 --> 00:44:32,320
Speaker 1: to thinking about are the ones from like black holes

843
00:44:32,360 --> 00:44:34,839
Speaker 1: that collide with each other, and before they do, they

844
00:44:35,040 --> 00:44:37,200
Speaker 1: orbit each other and emit a huge amount of energy

845
00:44:37,239 --> 00:44:41,279
Speaker 1: gravitational waves. Those are fairly high frequency, and we can

846
00:44:41,360 --> 00:44:44,720
Speaker 1: see those with our detectors. And so those detectors like Lago,

847
00:44:44,880 --> 00:44:48,280
Speaker 1: they can't see gravitational waves with really long wavelengths because

848
00:44:48,400 --> 00:44:50,560
Speaker 1: they don't make any change on the scale of like

849
00:44:50,600 --> 00:44:54,160
Speaker 1: the Earth. Even you need like a galaxy size detector

850
00:44:54,200 --> 00:44:59,279
Speaker 1: to see really long wavelengths gravitational waves. Amazingly, humans have

851
00:44:59,440 --> 00:45:04,560
Speaker 1: a galaxy size detector for gravitational waves. People have used pulsars,

852
00:45:04,640 --> 00:45:09,480
Speaker 1: which are extraordinary neutron stars that rotate with extreme regularity,

853
00:45:09,719 --> 00:45:12,960
Speaker 1: and by variations and their rotations, we can tell whether

854
00:45:13,000 --> 00:45:16,520
Speaker 1: space between us, and the pulsar has been squeezed or stretched.

855
00:45:16,840 --> 00:45:19,840
Speaker 1: In the last couple of years, we've even seen evidence

856
00:45:19,920 --> 00:45:24,280
Speaker 1: of very long wavelength gravitational waves using pulsar timing arrays.

857
00:45:24,520 --> 00:45:28,759
Speaker 1: Really an amazing piece of science. But even those might

858
00:45:28,880 --> 00:45:33,960
Speaker 1: be too short wavelength to see the early universe gravitational

859
00:45:34,000 --> 00:45:38,400
Speaker 1: waves because they're going to be extremely low frequency. The

860
00:45:38,440 --> 00:45:42,239
Speaker 1: pulsar timing arrays probably are seeing like a general gravitational

861
00:45:42,280 --> 00:45:45,560
Speaker 1: wave background from all sorts of black holes and acceleration.

862
00:45:45,640 --> 00:45:49,160
Speaker 1: I mean, everything you do creates gravitational waves. You wave

863
00:45:49,200 --> 00:45:51,880
Speaker 1: your hand in front of you, you're creating gravitational waves

864
00:45:52,000 --> 00:45:54,919
Speaker 1: because any kind of acceleration is going to create them.

865
00:45:55,320 --> 00:45:57,919
Speaker 1: So this is just like a gravitational wave noise through

866
00:45:57,960 --> 00:46:00,719
Speaker 1: the universe. But the ones from the early universe will

867
00:46:00,760 --> 00:46:04,480
Speaker 1: be unique because they won't have any specific source. They

868
00:46:04,520 --> 00:46:06,960
Speaker 1: won't come from this black hole, from that black hole.

869
00:46:07,120 --> 00:46:09,480
Speaker 1: They'll just fill the universe sort of the way the

870
00:46:09,520 --> 00:46:13,480
Speaker 1: cosmic microwave background light will, and they'll be very broadly

871
00:46:13,520 --> 00:46:16,640
Speaker 1: spread out across various frequencies. There'll be no big peak,

872
00:46:16,719 --> 00:46:20,600
Speaker 1: no clear power structure. It'll be a very broad frequency signal.

873
00:46:21,160 --> 00:46:23,480
Speaker 1: Even that will be very very hard to see, and

874
00:46:23,560 --> 00:46:26,520
Speaker 1: so the way people hope to see gravitational waves from

875
00:46:26,560 --> 00:46:29,799
Speaker 1: the early universe is not actually by seeing the gravitational

876
00:46:29,840 --> 00:46:36,040
Speaker 1: waves directly, but instead by seeing those gravitational waves affect

877
00:46:36,160 --> 00:46:39,520
Speaker 1: the cosmic microwave background light. So that light we talked

878
00:46:39,560 --> 00:46:41,800
Speaker 1: about earlier that was made three hundred and eighty thousand

879
00:46:41,880 --> 00:46:45,480
Speaker 1: years after T equals zero. When it was made, it

880
00:46:45,520 --> 00:46:49,080
Speaker 1: was affected by these gravitational waves that were already around

881
00:46:49,120 --> 00:46:52,000
Speaker 1: from the early universe. Because it gives that light a

882
00:46:52,040 --> 00:46:54,960
Speaker 1: special twist. Remember that light is a ripple in the

883
00:46:55,000 --> 00:46:58,520
Speaker 1: electromagnetic field, and the field is just like numbers in

884
00:46:58,600 --> 00:47:01,480
Speaker 1: space and the Higgs fields, for example, it's just like

885
00:47:01,520 --> 00:47:04,920
Speaker 1: a number at every location in space. But light is

886
00:47:04,960 --> 00:47:07,600
Speaker 1: a vector field, which means it's not just one number,

887
00:47:07,840 --> 00:47:11,000
Speaker 1: it's like three numbers. Or equivalently, you can think about

888
00:47:11,000 --> 00:47:13,160
Speaker 1: it like a little arrow with a length and a

889
00:47:13,239 --> 00:47:16,840
Speaker 1: direction and every point in space. And as light moves,

890
00:47:16,840 --> 00:47:19,919
Speaker 1: those arrows ripple, and it can do more than just move,

891
00:47:19,960 --> 00:47:22,840
Speaker 1: it can also spin right. So this is what we

892
00:47:22,920 --> 00:47:25,920
Speaker 1: call polarization of light. The same way that like if

893
00:47:25,920 --> 00:47:27,719
Speaker 1: you have a jump rope, you can shake it up

894
00:47:27,719 --> 00:47:29,560
Speaker 1: and down, or you can shake it sideways, or you

895
00:47:29,560 --> 00:47:31,720
Speaker 1: can shake it in like a swirly motion. This different

896
00:47:31,719 --> 00:47:35,000
Speaker 1: way for waves to propagate along that string. Same thing

897
00:47:35,040 --> 00:47:38,920
Speaker 1: for photons, and mathematically you can decompose them into what

898
00:47:38,960 --> 00:47:43,080
Speaker 1: are called emodes that are radial patterns and B modes

899
00:47:43,120 --> 00:47:46,920
Speaker 1: that are like twisting swirling patterns. Gravitational waves are the

900
00:47:46,920 --> 00:47:51,200
Speaker 1: only way we know to give B mode polarization to

901
00:47:51,280 --> 00:47:54,800
Speaker 1: the CMB light. There's something about how those gravitational waves

902
00:47:54,880 --> 00:47:58,200
Speaker 1: are stretching and squeezing the space while light is being

903
00:47:58,239 --> 00:48:02,280
Speaker 1: formed that gives it those B modes. Other gravitational waves

904
00:48:02,320 --> 00:48:05,919
Speaker 1: like black hole collisions late in the universe cannot give

905
00:48:06,040 --> 00:48:09,400
Speaker 1: like a broad pattern of B mode polarization. So if

906
00:48:09,440 --> 00:48:11,920
Speaker 1: you look at the cosmic microwave background light and you

907
00:48:12,000 --> 00:48:15,439
Speaker 1: measure its polarization and you see B modes, that would

908
00:48:15,480 --> 00:48:19,120
Speaker 1: be fascinating information about the early universe. And a few

909
00:48:19,200 --> 00:48:22,880
Speaker 1: years ago an experiment called BICEP two claimed to have

910
00:48:22,960 --> 00:48:27,880
Speaker 1: discovered it. Huge news rocked the science community until it

911
00:48:28,000 --> 00:48:30,680
Speaker 1: turned out that they made a mistake in their analysis

912
00:48:31,280 --> 00:48:35,520
Speaker 1: and they were relying on data from another experiment to

913
00:48:35,600 --> 00:48:37,920
Speaker 1: remove the effect of dust, but they didn't actually have

914
00:48:37,960 --> 00:48:40,800
Speaker 1: that data from that experiment. They took a screenshot of

915
00:48:40,840 --> 00:48:44,680
Speaker 1: a PowerPoint slide and misinterpreted it and used that as

916
00:48:44,680 --> 00:48:47,040
Speaker 1: the basis for their analysis. And they came up with

917
00:48:47,080 --> 00:48:50,520
Speaker 1: these big claims and had to walk it back. Very embarrassing.

918
00:48:51,040 --> 00:48:53,239
Speaker 1: Brian King wrote a book about it called Losing the

919
00:48:53,280 --> 00:48:55,560
Speaker 1: Nobel Prize. It's a fun.

920
00:48:55,400 --> 00:48:57,400
Speaker 2: Story, not for the people involved.

921
00:49:02,040 --> 00:49:03,760
Speaker 1: He tells it with a smile on his face.

922
00:49:03,800 --> 00:49:05,600
Speaker 2: I think was Brian Keating involved?

923
00:49:05,719 --> 00:49:09,799
Speaker 1: Oh yes, deeply. No, he's not embarrassing other people. He's

924
00:49:09,840 --> 00:49:14,800
Speaker 1: owning up to his own mistakes. Oh okay, their own mistakes. Anyway,

925
00:49:14,840 --> 00:49:18,160
Speaker 1: we have not yet seen that, So Gerard, that's how

926
00:49:18,160 --> 00:49:22,640
Speaker 1: we might differentiate early universe neutrinos from later universe neutrinos.

927
00:49:23,080 --> 00:49:26,440
Speaker 1: Or we might spot evidence for early universe gravitational waves,

928
00:49:26,480 --> 00:49:29,160
Speaker 1: either of which could tell us amazing things about what

929
00:49:29,280 --> 00:49:32,280
Speaker 1: happened in the first few moments after T equal zero,

930
00:49:32,760 --> 00:49:34,760
Speaker 1: none of which could tell us about what happened before

931
00:49:34,880 --> 00:49:37,520
Speaker 1: T equal zero. That's a whole other question.

932
00:49:37,640 --> 00:49:40,279
Speaker 2: Mark, which one do you think is more likely to

933
00:49:40,320 --> 00:49:41,440
Speaker 2: tell us something first?

934
00:49:41,760 --> 00:49:44,920
Speaker 1: Oh? Wow, great question. I think we probably will figure

935
00:49:44,960 --> 00:49:48,680
Speaker 1: out this be mode polarization of the CMB before we

936
00:49:48,760 --> 00:49:51,600
Speaker 1: figure out how to see these very low energy neutrinos.

937
00:49:51,840 --> 00:49:55,160
Speaker 1: But both communities are filled with super smart people working

938
00:49:55,160 --> 00:49:57,760
Speaker 1: hard and coming up with clever ideas that I could

939
00:49:57,800 --> 00:49:58,680
Speaker 1: never anticipate.

940
00:49:58,920 --> 00:50:02,320
Speaker 2: So we'll see, okay, and we'll see what Gerard thinks

941
00:50:02,360 --> 00:50:03,080
Speaker 2: about the answer.

942
00:50:05,760 --> 00:50:08,279
Speaker 1: Gerard listened to our answer and wrote back to me,

943
00:50:08,400 --> 00:50:10,600
Speaker 1: and he preferred to send a written response. I'll read

944
00:50:10,600 --> 00:50:14,520
Speaker 1: it for you now. Here's his reply quote. I didn't

945
00:50:14,520 --> 00:50:17,279
Speaker 1: know the gravitational waves would be like photons and be

946
00:50:17,360 --> 00:50:21,400
Speaker 1: stretched by their long journey through expanding space, lowering their frequency.

947
00:50:21,760 --> 00:50:24,520
Speaker 1: The idea of indirectly detecting them by their effect on

948
00:50:24,560 --> 00:50:28,720
Speaker 1: the CMB photon polarization is ingenious. I wonder how precise

949
00:50:28,760 --> 00:50:32,040
Speaker 1: the measurements would need to be before scientists could reconstruct

950
00:50:32,080 --> 00:50:35,799
Speaker 1: any earlier than CMB features. Nor did I know that

951
00:50:35,880 --> 00:50:39,479
Speaker 1: neutrinos would also lose energy through stretching space. I guess

952
00:50:39,520 --> 00:50:41,719
Speaker 1: I've always thought of them as particles, but we can

953
00:50:41,800 --> 00:50:44,440
Speaker 1: think of them as waves and a field. I am

954
00:50:44,480 --> 00:50:48,040
Speaker 1: always fascinated when science builds on an idea by extending

955
00:50:48,040 --> 00:50:51,320
Speaker 1: it to another domain, as in this example. Light waves stretch,

956
00:50:51,400 --> 00:50:55,200
Speaker 1: so gravity waves should stretch too. A further question evoked

957
00:50:55,200 --> 00:50:58,239
Speaker 1: by your description in the hot dense early universe, what

958
00:50:58,360 --> 00:51:01,720
Speaker 1: kind of structure might it have had. Would high energy

959
00:51:01,800 --> 00:51:05,160
Speaker 1: simply prevent anything from coalescing. I'm sure we will be

960
00:51:05,200 --> 00:51:08,840
Speaker 1: surprised by something no one has even imagined. Thank you

961
00:51:08,920 --> 00:51:11,080
Speaker 1: very much for that response, Giard. Let me answer some

962
00:51:11,120 --> 00:51:15,120
Speaker 1: of your follow up questions. Yes, neutrinos also lose energy

963
00:51:15,200 --> 00:51:18,919
Speaker 1: as they move through space because space is stretching. This

964
00:51:18,960 --> 00:51:22,680
Speaker 1: is a great example of the non conservation of energy

965
00:51:22,760 --> 00:51:27,560
Speaker 1: in an expanding universe. It applies to everything, particles and waves.

966
00:51:27,640 --> 00:51:30,680
Speaker 1: Particles in the end are really just ripples in quantum fields,

967
00:51:30,719 --> 00:51:34,319
Speaker 1: and they are affected by the expanding universe. You also ask,

968
00:51:34,719 --> 00:51:37,880
Speaker 1: what was the structure like in the hot dense early universe.

969
00:51:38,200 --> 00:51:40,600
Speaker 1: It's a great question, and structure is a tough way

970
00:51:40,640 --> 00:51:43,360
Speaker 1: to think about it, because in the very early universe

971
00:51:43,400 --> 00:51:47,080
Speaker 1: you have these quantum fields that are filled with frothing energy.

972
00:51:47,400 --> 00:51:50,080
Speaker 1: It's not like now when you have isolated energy and

973
00:51:50,120 --> 00:51:52,160
Speaker 1: you can think about a little ripple in the field

974
00:51:52,200 --> 00:51:55,360
Speaker 1: as a particle. It's like taking a thousand drops and

975
00:51:55,400 --> 00:51:57,200
Speaker 1: putting them in a glass. You don't really think about

976
00:51:57,239 --> 00:52:01,200
Speaker 1: drops anymore. Now you think about other emerging forms of

977
00:52:01,239 --> 00:52:04,839
Speaker 1: that water waves and other sorts of things. And so

978
00:52:04,960 --> 00:52:08,239
Speaker 1: what's going to happen the very early universe is that

979
00:52:08,320 --> 00:52:11,359
Speaker 1: those quantum fields will be filled with energy and we'll

980
00:52:11,400 --> 00:52:16,880
Speaker 1: get all sorts of weird bizarre effects. Thank you very

981
00:52:16,960 --> 00:52:19,239
Speaker 1: much to these listeners for sending in your questions, and

982
00:52:19,320 --> 00:52:22,400
Speaker 1: to everybody out there who drives this podcast forward with

983
00:52:22,520 --> 00:52:25,240
Speaker 1: your personal curiosity about the universe.

984
00:52:25,560 --> 00:52:28,640
Speaker 2: Please send us your questions at questions at danieland Kelly

985
00:52:28,719 --> 00:52:31,319
Speaker 2: dot org. And if you like the podcast, do you

986
00:52:31,360 --> 00:52:35,880
Speaker 2: think about leaving us a rating? We would really appreciate that, yes, exactly.

987
00:52:36,080 --> 00:52:37,880
Speaker 2: Help other people find the podcast so that they can

988
00:52:37,920 --> 00:52:38,879
Speaker 2: share their questions to.

989
00:52:40,040 --> 00:52:41,680
Speaker 1: Come for the science, stay for the pooh on.

990
00:52:41,680 --> 00:52:54,360
Speaker 2: The eggs, or whatever gross stuff floats your boat. Daniel

991
00:52:54,360 --> 00:52:58,080
Speaker 2: and Kelly's Extraordinary Universe is produced by iHeartRadio. We would

992
00:52:58,239 --> 00:53:00,120
Speaker 2: love to hear from you.

993
00:53:00,160 --> 00:53:03,200
Speaker 1: Would We want to know what questions you have about

994
00:53:03,200 --> 00:53:05,160
Speaker 1: this extraordinary Universe.

995
00:53:05,280 --> 00:53:08,200
Speaker 2: We want to know your thoughts on recent shows, suggestions

996
00:53:08,239 --> 00:53:11,239
Speaker 2: for future shows. If you contact us, we will get

997
00:53:11,280 --> 00:53:11,680
Speaker 2: back to you.

998
00:53:11,920 --> 00:53:15,480
Speaker 1: We really mean it. We answer every message. Email us

999
00:53:15,520 --> 00:53:18,719
Speaker 1: at questions at Danielankelly.

1000
00:53:17,760 --> 00:53:19,840
Speaker 2: Dot org, or you can find us on social media.

1001
00:53:19,960 --> 00:53:23,759
Speaker 2: We have accounts on x, Instagram, Blue Sky and on

1002
00:53:23,840 --> 00:53:25,799
Speaker 2: all of those platforms. You can find us at D

1003
00:53:26,239 --> 00:53:27,760
Speaker 2: and K Universe.

1004
00:53:27,960 --> 00:53:29,520
Speaker 1: Don't be shy, write to us