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Speaker 1: Hey, Katie, pain me a picture of where you are.

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Speaker 1: Tell me what you're seeing right now?

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Speaker 2: Okay, Well, I'm seeing sort of the corner of my

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Speaker 2: microphone because it's very close to my face. I'm seeing

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Speaker 2: a wall, my computer, some plants. Shall I go on?

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Speaker 1: No, now, let's add to the picture. Tell me what

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Speaker 1: sounds there are around you?

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Speaker 2: Well, sort of a very faint humming sound, your voice

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Speaker 2: in my ear, and I think the little footsteps of

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Speaker 2: my dog pacing outside waiting for me to be done

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Speaker 2: with this podcast.

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Speaker 1: And how about the smells in your sensorium?

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Speaker 2: Well, I smell my microphone, which does have a smell.

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Speaker 2: It's not gross, it's just, you know, microphone smell. I

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Speaker 2: think my husband is cooking something chicken maybe, or a

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Speaker 2: chicken like protein.

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Speaker 1: Does your microphone not smell like chicken? I thought everything

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Speaker 1: smells like chicken.

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Speaker 2: Hang on, let me see. I mean, if I really

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Speaker 2: think about chicken while smelling my microphone, I can make

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Speaker 2: that connection. Sure, all right?

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Speaker 1: And then the last sense is touch. What is your

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Speaker 1: sense of touch telling you?

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Speaker 2: Well, the sense of touch in my butt is telling

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Speaker 2: me that I should have invested in a much more

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Speaker 2: expensive ergonomic podcasting chair.

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Speaker 1: All right, So is that all I need to know

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Speaker 1: about what it's like to be you right now? To

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Speaker 1: pilot the meat machine that you call, Katie.

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Speaker 2: Golden, Well, there's little grimlins in my ear whispering things

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Speaker 2: at me. But other than that, yeah.

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Speaker 1: Those aren't gremlins, Katie, that's just me.

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Speaker 2: It's just a physicist. I don't know what to be

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Speaker 2: more afraid of the grimlins or a physicist physics grimlins.

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Speaker 3: Hi.

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Speaker 1: I'm Daniel. I'm a particle physicist and a professor at

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Speaker 1: UC Irvine, and I wonder what the world beyond my

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Speaker 1: senses is really like.

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Speaker 2: I'm Katie Golden. I host the podcast Creature Feature, which

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Speaker 2: is all about animal behavior and human behavior, and I

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Speaker 2: like to try to imagine what it's like to be

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Speaker 2: my dog by smelling other people's butts.

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Speaker 1: And how does that go over? I mean, I've been

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Speaker 1: Italy in a while, but I imagine that's still not a

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Speaker 1: typical kind of activity for.

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Speaker 2: Saying Hello, it's not I'm in jail.

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Speaker 1: You're doing everything you can to improve the reputations of

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Speaker 1: Americans abroad, right exactly, and welcome to the podcast. Daniel

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Speaker 1: and Jorge explain the universe in which we explore everything

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Speaker 1: that's out there in the universe, what people's butts smell like,

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Speaker 1: what the night sky looks like, what's actually out there

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Speaker 1: in deep space, how all the particles between our toes

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Speaker 1: are working to weave themselves together into our reality, and

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Speaker 1: how we sense experience and maybe even understand all of it.

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Speaker 1: My friend and co host Jorge can't be with us today,

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Speaker 1: but I'm very excited to have Katie Golden, one of

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Speaker 1: our regular and favorite guest hosts, to be with us

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Speaker 1: here today. Thanks Katie for joining us.

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Speaker 2: It feels good to be here.

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Speaker 1: And now I'm wondering if I ever do meet you

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Speaker 1: in person, Katie, if you're going to do more than

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Speaker 1: just shake my hand, if you're gonna.

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Speaker 2: Smell me up, like There's a lot you can tell

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Speaker 2: about a person just by huffing.

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Speaker 1: In that sense, you'll probably tell that I have dogs

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Speaker 1: and I have kids based on the random hairs on

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Speaker 1: my body.

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Speaker 2: The feel of the stickiness quotient is how I measure

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Speaker 2: whether someone has kids, Like, is there sticky patches on

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Speaker 2: your shirt? That's right, is in the shape of a

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Speaker 2: very small, curious little hand.

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Speaker 1: Do you have dried cheerios stuck to the side of

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Speaker 1: your shorts. If so, you have a toddler. But we're

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Speaker 1: not just interested in sensing other people. We are interested

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Speaker 1: in sensing the world. Everything we do in physics in

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Speaker 1: the end relies on these little data streams that we

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Speaker 1: get from the external universe that in the end we're

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Speaker 1: just assuming exists. We have a model for what's out there,

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Speaker 1: how it bangs around and creates information that we can

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Speaker 1: then perceive filter down into our minds and unravel into

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Speaker 1: a mathematical model in our heads that tries to explain

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Speaker 1: everything that we think is out there. But it seems

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Speaker 1: like kind of a long, complicated chain of events from

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Speaker 1: supernova explodes to somebody on Earth goes ooh, I think

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Speaker 1: I understand it. So on this podcast we try to

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Speaker 1: unravel all of those tricky, complicated things and make sure

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Speaker 1: you understand all of them.

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Speaker 2: It's so interesting to me that every sense we have

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Speaker 2: right is the direct result of physical interaction with the world,

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Speaker 2: because it feels strange since our mind seems very internal,

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Speaker 2: it seems very ice like, well, what I'm seeing is

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Speaker 2: kind of happening in my mind, But everything I'm seeing

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Speaker 2: like there's a direct sort of physics based interaction that's

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Speaker 2: happening between me and the world, and I don't know.

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Speaker 2: That makes me feel good. It makes me feel less

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Speaker 2: isolated in my own brain.

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Speaker 1: It really does a great job of reminding you that

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Speaker 1: information is physical, and that all observation is active. There's

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Speaker 1: no like passive just looking at the world. You are

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Speaker 1: absorbing it, you are consuming it, you are interacting with it.

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Speaker 1: When you see something, it's because photons are hitting your eye.

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Speaker 1: You're not just like passively observing it. And that of

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Speaker 1: course changes the way you feel about the universe and

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Speaker 1: has big philosophical implications for like quantum mechanics and what

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Speaker 1: happens when we collapse wave functions. But it also has

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Speaker 1: real consequences for what it means to like smell something nasty.

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Speaker 1: I mean, you're walking down the street and you're like,

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Speaker 1: m somebody didn't clean up after their dog. You know

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Speaker 1: that means poop molecules are hitting your nose.

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Speaker 2: When I have that realization, I think I was in

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Speaker 2: high school. It ruined my life world. I have never

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Speaker 2: gotten over that that like poopy smells, It's like, well,

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Speaker 2: the poopy particles are interacting with my nasal membranes in

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Speaker 2: some way. I don't like that and it is. Yeah,

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Speaker 2: it's a realization that ruined my life, and I'm glad

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Speaker 2: we can spread it to others.

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Speaker 1: And as we're going to learn later on, the sense

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Speaker 1: of smell the sense of taste are very closely intertwined,

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Speaker 1: and most of your experience of taste really is smell,

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Speaker 1: which means you're not just smelling that dog poop, you're

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Speaker 1: really tasting it delicious And we are excited to understand

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Speaker 1: this entire, delicious and disgusting universe in all of its glory.

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Speaker 1: And so today on the podcast, we're going to be

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Speaker 1: digging into the physics of this mechanism, how exactly information

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Speaker 1: gets banged around and propagated through all these amazing systems

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Speaker 1: into your brain so that you can experience the wonderful

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Speaker 1: smells of chicken cooking and the less wonderful smells of

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Speaker 1: dog residue.

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Speaker 2: I have smelled both today.

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Speaker 1: And so today on the podcast, we'll be answering the

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Speaker 1: question which forces power the human senses?

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Speaker 2: That sounds so cool. I'm imagining sort of my eyes

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Speaker 2: being powered by some kind of like futuristic technology.

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Speaker 1: Yeah, I guess power there can be confusing. It's not

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Speaker 1: like you have little coal power plants in your eyeballs

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Speaker 1: that are like making it all work in some sort

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Speaker 1: of steampunk version of your senses.

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Speaker 2: Now, I mean, as we all know, it's tiny grimlins

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Speaker 2: in there, running little projectors, the.

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Speaker 1: Little physics grimlins all the way down. Now, the idea

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Speaker 1: I think is to understand everything from a physics point

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Speaker 1: of view. I mean, you can zoom out to biology

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Speaker 1: and say, oh, yeah, we understand this bit and that

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Speaker 1: sell and they send signals or whatever. But I always

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Speaker 1: wonder from a microphysics point of view, like, what's really

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Speaker 1: happening at the lowest level. If in the end reductionism works,

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Speaker 1: and we can understand the whole universe in terms of

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Speaker 1: a few partsarticles and their interactions, and we should be

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Speaker 1: able to explain everything from human consciousness to supernova to

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Speaker 1: black holes to the evolution of the entire universe with

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Speaker 1: those fundamental laws. Of course, most of that is beyond

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Speaker 1: our ability currently, and the complex nature of these interactions

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Speaker 1: requires too much chaos for us to be able to compute.

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Speaker 1: But in some cases we can actually complete the thread.

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Speaker 1: We can't drill down and understand what is happening when

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Speaker 1: that chicken dinner enters your nose. How are you actually

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Speaker 1: seeing those things? What is the mechanism by which you

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Speaker 1: feel pain? In terms of the fundamental physics that we

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Speaker 1: do understand in our universe. So that's what we want

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Speaker 1: to dig into today.

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Speaker 2: I mean, it is really interesting because when you look

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Speaker 2: at biological processes like the smaller you get, you have

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Speaker 2: a very extensive, basically Rube Goldberg machine happening inside your

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Speaker 2: body on a tiny scale every time you sense something,

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Speaker 2: and then you zoom out and there's another Rube Goldberg

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Speaker 2: machine happening on a slightly larger scale. And I feel

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Speaker 2: like that's not too dissimilar to physics, although Goldberg machines

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Speaker 2: are operated by physics of force, which is not the

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Speaker 2: only kind of like physics we're talking about here, but

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Speaker 2: it's still it's still interesting that, you know, when you

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Speaker 2: have this whole complex process, domino effective physical phenomenon happening,

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Speaker 2: and then once it gets to your body and it

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Speaker 2: triggers an event, then you have a whole other complex

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Speaker 2: system of things that happens. There's so much just for

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Speaker 2: you to look at like a wadded up tissue. There's

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Speaker 2: so many things that have to happen so much.

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Speaker 1: Glorious physics in that experience of the watered up tissue.

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Speaker 1: But you know, I'm wondering how biologists feel about these machines,

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Speaker 1: these Rube Goldberg machines, because that's not exactly a compliment.

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Speaker 1: Like if I designed the machine to do something and

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Speaker 1: you said, wow, Daniel, that's kind of a Rube Goldberg machine,

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Speaker 1: I take it as like that's broke and overly complicated,

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Speaker 1: likely to fail, and could be better engineered. On the

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Speaker 1: other hand, I often hear biologists exclaiming that the wonders

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Speaker 1: of nature and the amazing things that evolution has been

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Speaker 1: able to engineer. So do you feel some pride in

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Speaker 1: evolution as an engineer or do you feel like embarrassed, like,

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Speaker 1: oh my gosh, this is ridiculous.

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Speaker 2: I think it could be both things, honestly. I mean,

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Speaker 2: I've heard of our immune systems being described as like

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Speaker 2: this amazing complicated ballet and dance, and that's true. But

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Speaker 2: then sometimes our immune system can act like an insane

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Speaker 2: traffic jam, just a horrible traffic snarl. And I think

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Speaker 2: these kinds of things happen in biold you or we

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Speaker 2: look at things like, you know, like the eyeball is incredible.

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Speaker 2: It's one of those things that make people question whether

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Speaker 2: evolution can be real. Of course, once you look at

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Speaker 2: the way in which ees develop over long periods of time,

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Speaker 2: you can see how it. You know, just after millions

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Speaker 2: of years you can get an eyeball. It's such an

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Speaker 2: elegant thing. And then on the other hand, we've got

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Speaker 2: some kind of weird uh things that happen in evolution,

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Speaker 2: you know, like these are called spandrels, where you have

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Speaker 2: an evolutionary trait that doesn't really have a purpose anymore,

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Speaker 2: or doesn't have any like a parent purpose, but it's

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Speaker 2: there because there's some other structural thing that occurred. And

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Speaker 2: then you just happen to have this thing because it

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Speaker 2: is a byproduct of other necessary structures. So it's not

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Speaker 2: meant to be necessarily elegant. It's just like what works works,

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Speaker 2: and sometimes it's elegant and sometimes it's not.

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Speaker 1: That's what you get when you leave the job up

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Speaker 1: to biology gremlins. All right, well, let's hear about what

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Speaker 1: some other gremlins had to say on this topic. I

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Speaker 1: reached out to listeners of the podcast to hear what

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Speaker 1: their thoughts were on the question. So before you hear

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Speaker 1: these answers, think to yourself, do you know which forces

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Speaker 1: power of the human senses. Here's what people had to say.

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Speaker 4: I'm going with the electromagnetic force, as I think all

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Speaker 4: of our sensors rely on that to send the signals

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Speaker 4: to our brain where we interpret them internally.

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Speaker 5: I suppose this would be the same as the forces

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Speaker 5: driving other metabolic processes. So ultimately the breakdown of ATP

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Speaker 5: to power some protein or enzyme that's involved in the

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Speaker 5: sensing signal transaction pathway, and then externally there would be

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Speaker 5: the force of the thing itself that's being sensed. Particularly exposed,

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Speaker 5: with the light, you'd have the photons striking rods or cones,

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Speaker 5: or in the case of sound, you'd have the vibrational

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Speaker 5: energy being sensed by the hairs. I guess with chemical

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Speaker 5: sensing it would be slightly more subtle, but there might

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Speaker 5: be some analogous process.

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Speaker 3: Well. I understand that the human senses are a collection

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Speaker 3: of receptors of very quantum phenomena such as light and

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Speaker 3: microscopic smell molecules. So I think that at the very end,

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Speaker 3: the fundamental forces such as electromagnetism and strong forces are

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Speaker 3: involved in somehow.

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Speaker 4: If you count equilibrium as a sense, then gravity would

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Speaker 4: affect that. Then touch, smell, here, and taste are all

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Speaker 4: physical contact ultimately, which is the interaction of molecules held

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Speaker 4: together by electromagnetism. And then vision is directly sensing the

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Speaker 4: electromagnetic spectrum. Ultimately everything is nerve impulses, which are electrochemicals.

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Speaker 4: So it seems like electromagnetism is the big winner.

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Speaker 1: I'd say the electromagnetic force is mostly responsible for powering

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Speaker 1: the human sensus.

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Speaker 3: Our entire nervous system basically works out in elecricity and

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Speaker 3: says our senses.

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Speaker 1: Are part of that. I'd say that's our usual suspect.

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Speaker 1: All right, We've got a lot of electromagnetism, but also

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Speaker 1: some gravity and chemistry and quantum mechanics mixed up in there.

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Speaker 2: I mean, I can't really disagree with this if we

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Speaker 2: blend all these answers together in sort of a stew

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Speaker 2: because as far as I understand it, like there's a

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Speaker 2: lot of different elements in terms of our ability to

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Speaker 2: perceive things. It's not always electromagnetic force, but that is

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Speaker 2: a major force and a lot of our sort of

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Speaker 2: the chain of events that occur that allow us to

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Speaker 2: perceive things. It's just there's so many different elements that

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Speaker 2: are happening all at once, or not all at once,

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Speaker 2: but in a sort of very quick rapid succession of events.

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Speaker 1: There are a lot of pieces at play. But one

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Speaker 1: of the things I love about the story we're telling

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Speaker 1: today is the eventual unity. How we achieve this sort

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Speaker 1: of physics goal of pulling everything together into one thing.

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Speaker 1: So I'm excited to get into that and take the

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Speaker 1: listeners on that saga and talk about what the fundamental

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Speaker 1: forces are that undergird the human senses.

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Speaker 2: So I understand fairly well the human senses and non

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Speaker 2: human senses, but I feel like I could use a

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Speaker 2: refresher on the main forces that exist in the physical

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Speaker 2: world that we can perceive, or at least something could perceive,

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Speaker 2: even if it's not a human.

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Speaker 1: Yeah, exactly. So we're going to map the human senses

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Speaker 1: to the fundamental forces. But are the fundamental forces? What

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Speaker 1: is the sort of target? What is the menu of options?

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Speaker 1: We have to describe stuff? So physics is all about

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Speaker 1: describing the universe, and humans have been observing stuff for

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Speaker 1: thousands of years and trying to describe it, And every

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Speaker 1: time we see something move in an unexplained way, get accelerated,

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Speaker 1: get a force applied to it, we come up with

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Speaker 1: a new force. We say, okay, well there must be

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Speaker 1: a new force that pushes things in this way. But

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Speaker 1: over thousands of years, we've worked to coalesce these things

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Speaker 1: into sort of the shortest list possible to say, oh,

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Speaker 1: the thing that does lightning is probably the same that

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Speaker 1: does that static electricity that zaps me. So we have

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Speaker 1: a list of the fundamental forces, the sort of basic

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Speaker 1: things that the universe can do, and that current list

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Speaker 1: has five things on it. So number one top of

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Speaker 1: the list is electricity, right, something humans have definitely known

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Speaker 1: about four thousands of years and a very important thing

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Speaker 1: in our lives. I mean, I drive an ev Electricity

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Speaker 1: is powering my entire life. You're listening to this device

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Speaker 1: using electricity. It's everywhere in our world. Hard to imagine

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Speaker 1: a universe without electricity.

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Speaker 2: How did we know about electricity before we had socks

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Speaker 2: and carpet.

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Speaker 1: Though Ben Franklin actually invented socks and carpets just to

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Speaker 1: do that experiment. Not a well known story, And we've

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Speaker 1: had sort of colloquial folk understanding of electricity for thousands

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Speaker 1: of years. But in the last couple of hundreds of years,

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Speaker 1: people doing experiments with literally like rags and glass rods

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Speaker 1: and all sorts of weird experiments have figured out that

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Speaker 1: we have charged particles, and those charge particles have these

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Speaker 1: electric fields that can push and pull on each other.

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Speaker 1: So you have two electrons, for example, they each have

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Speaker 1: an electric field and their electric fields can push on

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Speaker 1: other charged particles, and so that's the fundamental electrical force.

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Speaker 2: So can electrons because I know that electrons are often

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Speaker 2: a part of an atom or an atomic structure. Can

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Speaker 2: electrons just be out by themselves?

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Speaker 1: Oh? Yeah, Electrons do not have a curfew. They can

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Speaker 1: just be out there in the universe, and the Sun

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Speaker 1: produces a huge number of electrons shoots them out into

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Speaker 1: the universe. So if you take a spaceship through interstellar space,

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Speaker 1: you'll be swimming through a sea of electrons and protons

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Speaker 1: and all sorts of other particles. It's only when things

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Speaker 1: are cool, when these particles don't have enough velocity to escape,

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Speaker 1: that they're trapped into bonds. But the formation of the

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Speaker 1: atom is also electrical. Is the electrical force between the

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Speaker 1: proton and the electron that builds the atom. That's why

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Speaker 1: they bind together into hydrogen, and that's why atoms link

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Speaker 1: together into more complex molecules. So the structure of the

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Speaker 1: atom itself, and basically all of chemistry, the foundation of

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Speaker 1: that is electricity. It's all the forces of electrons on

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Speaker 1: each other and on nuclei.

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Speaker 2: So can you use electricity to facilitate chemical reactions in chemistry?

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Speaker 1: I mean, I think if you dig up a corpse

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Speaker 1: and lay them on a table and zap them with

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Speaker 1: lightning they come back to life, is that count as chemistry?

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Speaker 1: I think I saw that experiment somewhere.

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Speaker 2: That's true. I have seen muscle tissue. If you pour

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Speaker 2: like soy sauce or salt on it, it reacts like

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Speaker 2: the sort of electrical activity resumes, even though it's clearly

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Speaker 2: a dead thing. It can be a chunk of flesh.

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Speaker 2: And I think it's because of the sodium in the

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Speaker 2: salt or in the soy sauce, kind of like activating

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Speaker 2: these sodium channels and creating some kind of difference in

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Speaker 2: electrical voltage that allows there to be sort of this

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Speaker 2: twitching that happens. So if you see a video of

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Speaker 2: a fish or some meat on a plate kind of

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Speaker 2: twitching after you apply like soy sauce. It's not undead.

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Speaker 2: It's just a be re animated by the soy sauce.

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Speaker 3: Right.

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Speaker 1: But to give a serious answer to your question, yes, absolutely,

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Speaker 1: if you apply electricity or voltage or current to something,

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Speaker 1: youur depositing energy and that can definitely catalyze chemical reactions.

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Speaker 1: But you bring up another really important point, which is

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Speaker 1: how signaling happens. We know, of course, we can use

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Speaker 1: electrical signals to send information. You're listening to this podcast

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Speaker 1: with electrical signals, digital signals from computer to computer, and they're

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Speaker 1: probably analog signals and the speakers that are actually making

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Speaker 1: the sound that get to your ear. But also inside

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Speaker 1: our body, our nervous system uses these ionic channels, uses

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Speaker 1: charged particles and electrical forces two senden signals up and

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Speaker 1: down your nerves, which is why they move at almost

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Speaker 1: the speed of light.

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Speaker 2: Yeah, it's really fascinating because it's another thing is you

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Speaker 2: really can't chug soy sauce. It's bad for you. I'm

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Speaker 2: being silly, but it's also not a joke. If you

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Speaker 2: chug soy sauce, it's very dangerous because it interferes with

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Speaker 2: the ion channels in your brain, and it can actually

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Speaker 2: make it difficult for those electrical signals to occur in

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Speaker 2: your brain, and that's very dangerous. That can result in

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Speaker 2: coma or even death. So, you know, it's really interesting

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Speaker 2: how chemistry, right, like even basic chemistry, like the way

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Speaker 2: that sodium ions work and electricity, the tiny electrical impulses

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Speaker 2: in your brain work together and can be messed up

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Speaker 2: by soy sauce. Soy sauce is just so dangerous, you guys.

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Speaker 1: It's brewed up by soy goblins. I think they're quite

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Speaker 1: so dangerous.

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Speaker 2: I love soy sauce in moderation.

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Speaker 1: But that gives you a really cool picture of the

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Speaker 1: sort of electrical map of your body. And it reminds

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Speaker 1: you that your body is not just mechanical structures, not

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Speaker 1: just like cells and membranes and bones, but there are

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Speaker 1: electrical structures. There are also things that can get messed

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Speaker 1: up if you pour the wrong number of positively or

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Speaker 1: negatively charged particles in the wrong place. Your body is

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Speaker 1: sort of like a computer. If you poured soy sauce

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Speaker 1: on your computer, you would not expect it to operate

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Speaker 1: very well either. And it makes you wonder sometimes philosophically,

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Speaker 1: like what is this thing we call electric charge? Where

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Speaker 1: does it come from? And that's a tricky rabbit hole

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Speaker 1: to fall down, because really, fundamentally, in physics, charge is

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Speaker 1: something we assign. We say that some particles react in

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Speaker 1: the presence of electric fields, and that means that they're charged.

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Speaker 1: That's what charge means. And as we'll talk about it

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Speaker 1: in a minute when we get to the other forces,

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Speaker 1: we have other kinds of charge. Also, if you feel

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Speaker 1: the other fundamental forces, you are charged for those forces.

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Speaker 1: So we're used to talking about charge for an electrical sense,

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Speaker 1: we don't really know philosophically what it means. Why the

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Speaker 1: electron has a charge, Why these other particles have charges.

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Speaker 1: Some particles don't have charges. It's just something we observe

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Speaker 1: and describe.

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Speaker 2: So like all electrons have some kind of charge, but

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Speaker 2: we really like when do we feel that?

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Speaker 3: Right?

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Speaker 2: Like when can we observe that charge? Because like you know,

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Speaker 2: you have your door handle in your socks and somehow

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Speaker 2: by rubbing your socks on the carpet, now when you

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Speaker 2: touch the door handle, you have a charge that you

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Speaker 2: can actually sense a little zap. So what happens to

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Speaker 2: these charges to make us actually notice them, like lightning happens.

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Speaker 2: We can notice that even though this charge can be

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Speaker 2: all around us at this like sub atomic level without

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Speaker 2: us noticing.

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Speaker 1: Yeah, great question. I mean fundamentally, we notice something is

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Speaker 1: charged when it's moved by an electrical field. And that's

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Speaker 1: the definition of charge. If you give me a new

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Speaker 1: particle I'd never seen before, one of the first things

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Speaker 1: I would do would be descended through an electric field

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Speaker 1: and see is it accelerated by the field? Is it

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Speaker 1: pushed around by the field. If so, then it has

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Speaker 1: an electric charge, because that's the definition of it. When

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Speaker 1: you rub a cloth onto a glass rod, you're stripping

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Speaker 1: some of those charged particles from one to the other.

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Speaker 1: You're creating an imbalance, which creates an electric field, which

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Speaker 1: is then can accelerate any charge particle across it, which

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Speaker 1: is why you get that zap when things come back

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Speaker 1: close enough for that field to break down the air

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Speaker 1: and let the electrons pass through the other direction and

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Speaker 1: create that spark. So in the end, really charge is

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Speaker 1: about being moved by an electric field, which feels a

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Speaker 1: little circular because we also define an electric field to

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Speaker 1: be something created by a charge, and so that gives

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Speaker 1: you a glimpse into how deeply we do and do

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Speaker 1: not understand the fundamental forces.

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Speaker 2: It's very interesting. So it's like you have to have

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Speaker 2: some kind of imbalance in charge in order for us

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Speaker 2: to kind of sense that charge.

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Speaker 1: Yeah, exactly. If everything is totally neutral, then there are

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Speaker 1: no forces.

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Speaker 2: So I'm going to test this theory out by rubbing

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Speaker 2: my socks against the carpet and zap my husband while

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Speaker 2: he's trying to cook chicken. So I'm going to go

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Speaker 2: do that and I will report my experiment back when

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Speaker 2: we return. So the experiment was an unqualified success. I

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Speaker 2: did zat my husband. He said, ouch, what are you doing.

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00:23:30,240 --> 00:23:34,600
Speaker 2: I'm just trying to cook some chicken. So we have

440
00:23:34,920 --> 00:23:39,600
Speaker 2: talked about electrical forces, that they exist in your body,

441
00:23:39,640 --> 00:23:42,800
Speaker 2: they exist outside of your body. It is something that

442
00:23:43,160 --> 00:23:48,080
Speaker 2: we see in lightning, in you know, static electricity, and

443
00:23:48,440 --> 00:23:52,639
Speaker 2: in our own bodies, in our synapses, in our brain

444
00:23:52,800 --> 00:23:56,200
Speaker 2: and in our along these long nerve fibers on our

445
00:23:56,240 --> 00:23:59,720
Speaker 2: spinal cord. So what other forces are there in the

446
00:23:59,720 --> 00:24:01,440
Speaker 2: world that can affect us?

447
00:24:01,720 --> 00:24:04,680
Speaker 1: So we've seen other stuff, not just electricity to spark

448
00:24:04,720 --> 00:24:08,359
Speaker 1: our husbands and to fry trees in a lightning storm.

449
00:24:08,480 --> 00:24:12,000
Speaker 1: But like magnets, right, magnets are definitely a different thing

450
00:24:12,240 --> 00:24:15,280
Speaker 1: than electricity. These are things we've known about for thousands

451
00:24:15,320 --> 00:24:17,480
Speaker 1: of years, and a couple of hundred years ago, a

452
00:24:17,600 --> 00:24:21,880
Speaker 1: clever Scotsman helped us understand that magnetic fields, which are

453
00:24:21,960 --> 00:24:24,880
Speaker 1: very similar to electric fields, actually fit together with them

454
00:24:25,080 --> 00:24:28,960
Speaker 1: into a blended concept called electromagnetism. But that doesn't mean

455
00:24:29,000 --> 00:24:32,200
Speaker 1: that electricity and magnetism are the same thing. A lot

456
00:24:32,200 --> 00:24:34,879
Speaker 1: of people get confused and imagine that the union of

457
00:24:34,920 --> 00:24:38,720
Speaker 1: electricity and magnetism into one concept means that they are

458
00:24:38,880 --> 00:24:41,200
Speaker 1: the same thing. But it's more like how the union

459
00:24:41,280 --> 00:24:42,840
Speaker 1: of the front of an elephant and the back of

460
00:24:42,840 --> 00:24:45,440
Speaker 1: an elephant, and give you a whole elephant, doesn't mean

461
00:24:45,480 --> 00:24:47,280
Speaker 1: the front in the back are the same thing.

462
00:24:47,600 --> 00:24:50,000
Speaker 2: Yes, and you will learn that if you're an elephant

463
00:24:50,080 --> 00:24:52,240
Speaker 2: keeper and you're behind an elephant.

464
00:24:51,920 --> 00:24:53,600
Speaker 1: Go out and take some data. You will learn that

465
00:24:53,720 --> 00:24:55,879
Speaker 1: very quickly. Sort of how two sides of the coin

466
00:24:56,000 --> 00:24:58,720
Speaker 1: make more sense when you think of them together than

467
00:24:58,720 --> 00:25:01,040
Speaker 1: when you think about them separately. But heads does not

468
00:25:01,160 --> 00:25:04,680
Speaker 1: equal tails, So magnetism really is its own thing. It's

469
00:25:04,760 --> 00:25:08,480
Speaker 1: just like a different part of electromagnetism, and it's fascinating

470
00:25:08,480 --> 00:25:11,440
Speaker 1: because it's very similar to electricity, but it's also very different.

471
00:25:11,800 --> 00:25:14,120
Speaker 1: One way in which it's different is that there are

472
00:25:14,119 --> 00:25:18,399
Speaker 1: no particles out there with like magnetic charge. We have

473
00:25:18,440 --> 00:25:20,879
Speaker 1: particles like electrons that can give you electric fields, but

474
00:25:20,920 --> 00:25:23,160
Speaker 1: there are no particles that just sit there and give

475
00:25:23,200 --> 00:25:26,639
Speaker 1: you magnetic fields. Magnetic fields only come from the motion

476
00:25:27,200 --> 00:25:30,359
Speaker 1: of electric charges, like a current will give you a

477
00:25:30,359 --> 00:25:32,879
Speaker 1: magnetic field, or something rotating with a charge on it

478
00:25:32,920 --> 00:25:34,880
Speaker 1: will give you a magnetic field. There are no particles

479
00:25:34,880 --> 00:25:37,240
Speaker 1: out there with a pure magnetic charge, which makes it

480
00:25:37,280 --> 00:25:38,720
Speaker 1: pretty different from electricity.

481
00:25:38,880 --> 00:25:42,280
Speaker 2: Now, hang on, Daniel, you say that magnetism is from

482
00:25:42,560 --> 00:25:47,280
Speaker 2: sort of the movement of charged particles. But I have

483
00:25:47,640 --> 00:25:52,560
Speaker 2: two magnets. They look pretty motionless, and then I put

484
00:25:52,600 --> 00:25:56,399
Speaker 2: them next to each other, and they still either stick

485
00:25:56,440 --> 00:26:00,200
Speaker 2: together or push each other apart. What's happening with magnet

486
00:26:00,520 --> 00:26:05,119
Speaker 2: If this is something that can be produced by an

487
00:26:05,160 --> 00:26:08,880
Speaker 2: electrical field, like something that is moving, the magnets themselves

488
00:26:08,880 --> 00:26:11,920
Speaker 2: do not, to my eyes, appear to be moving unless

489
00:26:12,000 --> 00:26:15,760
Speaker 2: I'm actually forcing them together through magnetism.

490
00:26:15,320 --> 00:26:17,560
Speaker 1: And you probably are not running an electric current through it.

491
00:26:17,560 --> 00:26:20,000
Speaker 1: So you're wondering, like, where's the motion of the charges

492
00:26:20,040 --> 00:26:24,240
Speaker 1: that's giving me these magnetic fields, And it's the electrons spinning,

493
00:26:24,400 --> 00:26:27,919
Speaker 1: and these little quantum particles electrons and protons whatever, they

494
00:26:27,960 --> 00:26:30,920
Speaker 1: have a property called quantum spin, which is not physical spin.

495
00:26:31,040 --> 00:26:34,040
Speaker 1: It's not like they're actually little balls that are literally spinning.

496
00:26:34,359 --> 00:26:36,880
Speaker 1: It's a different kind of quantum mechanical property. Check out

497
00:26:36,880 --> 00:26:40,520
Speaker 1: our podcast episode about what is quantum spin. But it

498
00:26:40,600 --> 00:26:43,920
Speaker 1: is definitely a kind of spin. It carries angular momentum

499
00:26:43,960 --> 00:26:47,239
Speaker 1: for sure, and it does generate a magnetic field. So

500
00:26:47,280 --> 00:26:50,480
Speaker 1: a charged particle with quantum spin has also a little

501
00:26:50,520 --> 00:26:53,920
Speaker 1: magnetic field to it, and enough of these particles line

502
00:26:54,000 --> 00:26:56,080
Speaker 1: up in your little blob of metal and it becomes

503
00:26:56,119 --> 00:26:58,960
Speaker 1: a permanent magnet. So that's how a fridge magnet works.

504
00:26:59,000 --> 00:27:01,800
Speaker 1: There really is a kind of motion inside of it

505
00:27:01,840 --> 00:27:04,240
Speaker 1: that's creating a magnetic field. And you might think, hold on,

506
00:27:04,280 --> 00:27:06,520
Speaker 1: doesn't that contradict what Daniel just said about how there

507
00:27:06,560 --> 00:27:09,560
Speaker 1: are no like objects just that have magnetic fields. Well,

508
00:27:09,560 --> 00:27:11,960
Speaker 1: the fridge magnet doesn't just have a magnetic field the

509
00:27:11,960 --> 00:27:14,479
Speaker 1: way an electron has an electric field. It has a

510
00:27:14,520 --> 00:27:18,080
Speaker 1: dipole field. It has a north and a south. Overall,

511
00:27:18,280 --> 00:27:21,000
Speaker 1: there's no net magnetic field because it's a north and

512
00:27:21,000 --> 00:27:23,720
Speaker 1: a south. They cancel each other out. There's no particle

513
00:27:23,720 --> 00:27:25,800
Speaker 1: out there that just has like a north or just

514
00:27:25,920 --> 00:27:29,280
Speaker 1: has a south. That would be something we call a monopole. Though,

515
00:27:29,280 --> 00:27:31,400
Speaker 1: when an electron can just have like a negative field

516
00:27:31,440 --> 00:27:34,480
Speaker 1: and a proton can have a positive field. In magnetism,

517
00:27:34,560 --> 00:27:37,160
Speaker 1: you can only have the north and south together because

518
00:27:37,160 --> 00:27:40,119
Speaker 1: it's generated by the motion of an electric charge.

519
00:27:40,200 --> 00:27:42,719
Speaker 2: It's interesting. So it's like if you're sort of in

520
00:27:42,760 --> 00:27:45,800
Speaker 2: a pool, like you're a little electron and you're moving

521
00:27:45,920 --> 00:27:48,880
Speaker 2: back and forth, there's always gonna be waves behind you

522
00:27:48,920 --> 00:27:51,040
Speaker 2: and in front of you. There's no such thing as

523
00:27:51,080 --> 00:27:53,600
Speaker 2: like if you're moving back and forth, it's not just

524
00:27:53,600 --> 00:27:56,560
Speaker 2: going to generate waves in front of you and not

525
00:27:56,680 --> 00:27:57,760
Speaker 2: behind you exactly.

526
00:27:57,800 --> 00:28:01,200
Speaker 1: It's always in balance. There's no over a magnetic charge

527
00:28:01,240 --> 00:28:04,600
Speaker 1: in the universe. It's just fascinating because it's a stark asymmetry.

528
00:28:04,960 --> 00:28:08,280
Speaker 1: On one hand, magnetism works exactly the same way as electricity.

529
00:28:08,320 --> 00:28:11,000
Speaker 1: You write down the equations, they're all the same equations,

530
00:28:11,200 --> 00:28:14,320
Speaker 1: except for this one key difference that there are no

531
00:28:14,920 --> 00:28:18,520
Speaker 1: pure sources of magnetism in the universe that we know about.

532
00:28:18,920 --> 00:28:22,040
Speaker 1: Check out our podcast episode on magnetic monopoles and the

533
00:28:22,160 --> 00:28:24,480
Speaker 1: Hunt for them. But it means that magnetism is a

534
00:28:24,520 --> 00:28:28,600
Speaker 1: sort of weird shadow version of electricity, and together the

535
00:28:28,640 --> 00:28:31,800
Speaker 1: two can do this incredible dance. The electric fields and

536
00:28:31,800 --> 00:28:36,720
Speaker 1: the magnetic fields can oscillate together. The electromagnetic oscillation is

537
00:28:36,720 --> 00:28:42,120
Speaker 1: something we call light. Photons are oscillations in the electromagnetic

538
00:28:42,200 --> 00:28:46,560
Speaker 1: field as it slashes back and forth between electricity and magnetism.

539
00:28:46,760 --> 00:28:51,880
Speaker 2: That's really interesting. I've never seen light occur just with magnets,

540
00:28:52,200 --> 00:28:55,600
Speaker 2: but I have seen light, you know, occur from electricity.

541
00:28:55,880 --> 00:29:00,960
Speaker 2: Natural sort of occurring plasma from a light is very bright,

542
00:29:01,120 --> 00:29:06,440
Speaker 2: So it's interesting that electromagnetism is like, is there like

543
00:29:06,480 --> 00:29:09,120
Speaker 2: a magnetic field around lightning?

544
00:29:09,440 --> 00:29:12,680
Speaker 1: There are definitely magnetic fields around lightning, absolutely, because you

545
00:29:12,680 --> 00:29:15,600
Speaker 1: have lots of very highly charged particles moving at very

546
00:29:15,640 --> 00:29:18,960
Speaker 1: high speed. So you could definitely detect lightning using a compass.

547
00:29:19,320 --> 00:29:22,160
Speaker 2: So is that a safe way to predict whether you're

548
00:29:22,160 --> 00:29:24,360
Speaker 2: gonna get hit by lightning? If you hold a compass

549
00:29:24,400 --> 00:29:25,680
Speaker 2: out and it starts going crazy.

550
00:29:26,800 --> 00:29:29,760
Speaker 1: I think compasses will definitely go crazy in a lightning storm.

551
00:29:29,960 --> 00:29:31,640
Speaker 1: So if you see your compass going crazy, it means

552
00:29:31,680 --> 00:29:35,240
Speaker 1: either aliens are arriving or you might be about to

553
00:29:35,240 --> 00:29:37,480
Speaker 1: get zapped. Either way, you might get zapped.

554
00:29:37,760 --> 00:29:41,720
Speaker 2: I'm gonna believe in the aliens option. Have you ever

555
00:29:41,800 --> 00:29:45,000
Speaker 2: wondered what would happen if you put like a giant

556
00:29:45,040 --> 00:29:46,600
Speaker 2: magnet next to your brain.

557
00:29:48,360 --> 00:29:50,640
Speaker 1: I've done that. Actually, I've had an MRI that's basically

558
00:29:50,720 --> 00:29:52,160
Speaker 1: a giant magnet next to your brain.

559
00:29:52,440 --> 00:29:55,400
Speaker 2: That is true. That's why you can't bring metal into

560
00:29:55,760 --> 00:29:59,680
Speaker 2: an MRI room, otherwise it's going to cause a big

561
00:29:59,720 --> 00:30:00,320
Speaker 2: problem problem.

562
00:30:00,560 --> 00:30:03,800
Speaker 1: And for our particle accelerators, we have huge magnets in

563
00:30:03,840 --> 00:30:07,440
Speaker 1: these facilities underground to bend charge particles. And sometimes you

564
00:30:07,480 --> 00:30:09,840
Speaker 1: go down there when the magnet's on and they tell you,

565
00:30:09,960 --> 00:30:12,960
Speaker 1: like take off everything. You know, screwdrivers can become weapons.

566
00:30:13,040 --> 00:30:14,880
Speaker 1: I once saw a woman who forgot to take off

567
00:30:14,880 --> 00:30:18,360
Speaker 1: her earrings and her ear lobes were tugged very very stiffly.

568
00:30:19,240 --> 00:30:24,320
Speaker 2: Ooh ah, that is that's like some final destination stuff

569
00:30:24,440 --> 00:30:29,640
Speaker 2: right there. So, like you can use electromagnetic forces to

570
00:30:29,920 --> 00:30:34,400
Speaker 2: impact the brain and actually kind of selectively shut off

571
00:30:34,520 --> 00:30:38,320
Speaker 2: parts of the brain. It's a reversible process. That's done

572
00:30:38,440 --> 00:30:41,920
Speaker 2: sometimes in research, sometimes in a clinical setting where you're

573
00:30:42,200 --> 00:30:46,360
Speaker 2: either stimulating or sort of shutting down parts of the

574
00:30:46,400 --> 00:30:51,600
Speaker 2: brain using electromagnetic forces. It is very creepy to me.

575
00:30:51,800 --> 00:30:54,160
Speaker 2: I'd be very interested to see what it feels like

576
00:30:54,240 --> 00:30:56,400
Speaker 2: to have like parts of your brain shut off, but

577
00:30:56,640 --> 00:31:00,080
Speaker 2: it's also scares me a little bit. I don't know

578
00:31:00,120 --> 00:31:02,360
Speaker 2: if I'd ever want to sign up for a study that.

579
00:31:02,440 --> 00:31:05,480
Speaker 1: Is terrifying, especially if it's computer controlled, which means eventually

580
00:31:05,640 --> 00:31:07,200
Speaker 1: there'll be an app for that where you can like

581
00:31:07,240 --> 00:31:08,520
Speaker 1: shut off parts of your brain.

582
00:31:08,800 --> 00:31:10,200
Speaker 2: This is how the AI win.

583
00:31:13,000 --> 00:31:14,160
Speaker 1: The computer gremlins.

584
00:31:14,560 --> 00:31:18,360
Speaker 2: So we've talked about electricity, We've talked about magnetism and

585
00:31:18,400 --> 00:31:21,240
Speaker 2: the way the two are like different sides of the

586
00:31:21,280 --> 00:31:25,480
Speaker 2: same coin. Are there other forces out there that you

587
00:31:25,520 --> 00:31:30,120
Speaker 2: know I could taste or touch or smell or know about.

588
00:31:30,240 --> 00:31:31,960
Speaker 1: Yeah, there are. The sort of next natural one on

589
00:31:32,040 --> 00:31:34,960
Speaker 1: the list is the weak nuclear force. This is the

590
00:31:34,960 --> 00:31:37,920
Speaker 1: force that lets us see neutrinos, which for example, have

591
00:31:38,080 --> 00:31:41,840
Speaker 1: no electric charge, no magnetic field, cannot be seen at

592
00:31:41,840 --> 00:31:46,400
Speaker 1: all with electromagnetism, but neutrinos carry a weak charge, a

593
00:31:46,480 --> 00:31:50,120
Speaker 1: different kind of charge, not electrical charge, but a weak charge,

594
00:31:50,400 --> 00:31:53,000
Speaker 1: so they interact via the weak force, which is a

595
00:31:53,120 --> 00:31:56,400
Speaker 1: very different kind of force. It doesn't use photons to interact.

596
00:31:56,400 --> 00:31:59,760
Speaker 1: That has wn z bosons, and it's called the weak force.

597
00:32:00,120 --> 00:32:03,960
Speaker 1: It's not nearly as powerful as electromagnetism. It's much much weaker,

598
00:32:04,400 --> 00:32:07,240
Speaker 1: but it does have an impact on our life and universe.

599
00:32:07,440 --> 00:32:11,320
Speaker 1: For example, is the cause of most nuclear decay as

600
00:32:11,400 --> 00:32:15,320
Speaker 1: neutrons turn into protons, for example, via beta decay, which

601
00:32:15,360 --> 00:32:18,920
Speaker 1: is a weak process. So a lot of radioactivity is

602
00:32:19,040 --> 00:32:20,400
Speaker 1: due to the weak force.

603
00:32:20,640 --> 00:32:24,000
Speaker 2: Now you say it is a weak force, and then you,

604
00:32:24,080 --> 00:32:28,200
Speaker 2: in the same sentence say radioactivity, which to me is

605
00:32:28,200 --> 00:32:32,040
Speaker 2: something that is powerful and scary. How can a weak

606
00:32:32,080 --> 00:32:36,400
Speaker 2: force be behind something like something being radioactive, which can

607
00:32:36,440 --> 00:32:37,200
Speaker 2: really mess with you.

608
00:32:37,640 --> 00:32:40,200
Speaker 1: Yeah, it's a great question. By week, we really don't

609
00:32:40,240 --> 00:32:43,960
Speaker 1: mean that it's not capable of giving particles high speed.

610
00:32:44,000 --> 00:32:46,560
Speaker 1: That it doesn't mean that it can't give particles a kick.

611
00:32:46,800 --> 00:32:49,120
Speaker 1: It means that it's less likely to wake up and

612
00:32:49,200 --> 00:32:52,000
Speaker 1: do its thing, like if you shoot a nutrino through

613
00:32:52,080 --> 00:32:55,480
Speaker 1: a wall, it will mostly ignore those other particles because

614
00:32:55,480 --> 00:32:58,800
Speaker 1: it has a very low probability of interacting. So the

615
00:32:58,800 --> 00:33:02,000
Speaker 1: weakness is really about a chances of it happening, not

616
00:33:02,120 --> 00:33:04,880
Speaker 1: about the force that it can apply. That's why neutrinos

617
00:33:04,880 --> 00:33:07,520
Speaker 1: can pass through like a light year of lead without

618
00:33:07,600 --> 00:33:10,120
Speaker 1: kicking into any particle. But if they do, if one

619
00:33:10,120 --> 00:33:12,840
Speaker 1: of those particles rolls the right number on the many

620
00:33:12,920 --> 00:33:16,600
Speaker 1: billion sided die and actually does interact with that neutrino,

621
00:33:16,800 --> 00:33:19,120
Speaker 1: it can get a substantial kick. You can have fairly

622
00:33:19,280 --> 00:33:23,040
Speaker 1: high energy interactions using the weak force. It's more about

623
00:33:23,080 --> 00:33:25,640
Speaker 1: the chances of it happening than the power that it

624
00:33:25,680 --> 00:33:26,360
Speaker 1: can transmit.

625
00:33:26,560 --> 00:33:29,200
Speaker 2: I feel like you guys should have named this the

626
00:33:29,280 --> 00:33:33,360
Speaker 2: shy forces then, because that neutrino is just shy, but

627
00:33:33,440 --> 00:33:35,960
Speaker 2: when you get to know it be pretty powerful.

628
00:33:36,240 --> 00:33:37,480
Speaker 1: Yeah, exactly.

629
00:33:37,960 --> 00:33:41,360
Speaker 2: So if there are weak forces, can I guess that

630
00:33:41,440 --> 00:33:43,400
Speaker 2: there are also strong forces.

631
00:33:43,600 --> 00:33:46,440
Speaker 1: Yes, this is one place in which maybe particle physics

632
00:33:46,440 --> 00:33:49,280
Speaker 1: has done a good job, because there is the force.

633
00:33:49,320 --> 00:33:52,840
Speaker 1: We call these strong nuclear force. This affects particles that

634
00:33:52,920 --> 00:33:56,479
Speaker 1: have a strong nuclear charge, which we also call color.

635
00:33:56,640 --> 00:34:00,440
Speaker 1: To be extra confusing, so some particles like quarks, for example,

636
00:34:00,760 --> 00:34:01,440
Speaker 1: have color.

637
00:34:01,680 --> 00:34:02,720
Speaker 2: Get your own word.

638
00:34:02,800 --> 00:34:06,840
Speaker 1: Wait a minute, there's red, green, and blue quarks. Any

639
00:34:06,880 --> 00:34:10,400
Speaker 1: particle that has color will feel the strong nuclear force.

640
00:34:10,680 --> 00:34:14,280
Speaker 1: The strong nuclear force super duper powerful, lots of energy,

641
00:34:14,320 --> 00:34:18,239
Speaker 1: and very likely to interact. Basically, almost always does interact,

642
00:34:18,640 --> 00:34:21,080
Speaker 1: and so quarks are never seen by themselves. They are

643
00:34:21,080 --> 00:34:24,320
Speaker 1: always busy interacting with each other and forming bound states

644
00:34:24,400 --> 00:34:28,840
Speaker 1: like protons and neutrons, which are just collections of quarks

645
00:34:29,080 --> 00:34:31,759
Speaker 1: wrapped together into a blob. So the strong nuclear force

646
00:34:31,840 --> 00:34:34,319
Speaker 1: is very, very powerful and fundamental to the way our

647
00:34:34,320 --> 00:34:37,200
Speaker 1: whole universe works because it's built the proton, which is

648
00:34:37,280 --> 00:34:39,920
Speaker 1: really the building block of the atom, which is pretty

649
00:34:39,920 --> 00:34:41,600
Speaker 1: important when you're making a chicken dinner.

650
00:34:41,760 --> 00:34:44,440
Speaker 2: All. Let my husband know to not forget the atoms

651
00:34:45,040 --> 00:34:47,880
Speaker 2: in the chicken dinner. So, because this is such a

652
00:34:47,920 --> 00:34:51,360
Speaker 2: strong force, is that why you know splitting an atom

653
00:34:51,480 --> 00:34:53,840
Speaker 2: causes such a huge effect?

654
00:34:54,280 --> 00:34:57,360
Speaker 1: Yes, exactly. And this can be a little confusing because

655
00:34:57,360 --> 00:34:59,600
Speaker 1: we think of the strong force as holding a proton

656
00:34:59,640 --> 00:35:03,440
Speaker 1: together or holding a neutron together, and technically those objects

657
00:35:03,480 --> 00:35:06,520
Speaker 1: are color neutral, they don't have an overall strong charge

658
00:35:06,560 --> 00:35:09,200
Speaker 1: to them. But the strong force is also capable of

659
00:35:09,280 --> 00:35:13,640
Speaker 1: holding those protons and neutrons together into the nucleus because

660
00:35:13,680 --> 00:35:16,640
Speaker 1: while overall the proton is not charged and the neutron

661
00:35:16,760 --> 00:35:19,760
Speaker 1: is not charged, there is a little bit of residual charge,

662
00:35:20,080 --> 00:35:22,440
Speaker 1: because these quarks are not all on top of each other,

663
00:35:22,480 --> 00:35:25,160
Speaker 1: they're in different places inside the protons, So like one

664
00:35:25,200 --> 00:35:26,960
Speaker 1: side of a proton will have a little bit of

665
00:35:27,000 --> 00:35:29,000
Speaker 1: color charge and the other side will have a little

666
00:35:29,040 --> 00:35:31,759
Speaker 1: bit of color charge, and that's enough to stick the

667
00:35:31,760 --> 00:35:34,840
Speaker 1: protons and neutrons together. And then when you split the atom,

668
00:35:34,960 --> 00:35:38,680
Speaker 1: you're breaking those bonds and releasing energy. So even just

669
00:35:38,719 --> 00:35:41,600
Speaker 1: this little extra residual bit of the strong force is

670
00:35:41,640 --> 00:35:44,960
Speaker 1: powerful enough to power nuclear weapons and nuclear reactors and

671
00:35:44,960 --> 00:35:47,240
Speaker 1: all sorts of crazy stuff. It's a very strong force.

672
00:35:47,680 --> 00:35:51,279
Speaker 2: It makes me think of two velcrow balls. Like the

673
00:35:51,320 --> 00:35:56,399
Speaker 2: balls themselves don't necessarily have any attraction to each other,

674
00:35:56,560 --> 00:36:01,600
Speaker 2: but the velcrow little individual hooks and tiny tiny loops

675
00:36:01,800 --> 00:36:04,600
Speaker 2: do have some attraction to each other. Well, it's not

676
00:36:04,640 --> 00:36:08,120
Speaker 2: a great metaphor because we're talking about velcrow versus quarks,

677
00:36:08,160 --> 00:36:10,960
Speaker 2: but like the quirks that make up the proton and

678
00:36:11,000 --> 00:36:14,520
Speaker 2: neutrons are attracted to each other, have a force pulling

679
00:36:14,520 --> 00:36:17,919
Speaker 2: them together. So they're like the parts are greater than

680
00:36:18,280 --> 00:36:20,719
Speaker 2: the sum of the parts, which is the opposite of

681
00:36:20,760 --> 00:36:21,560
Speaker 2: what it usually is.

682
00:36:22,160 --> 00:36:25,520
Speaker 1: Yeah, exactly. It's fascinating and it's complicated. We don't really

683
00:36:25,640 --> 00:36:28,360
Speaker 1: understand how the nucleus holds together. In some cases, you

684
00:36:28,400 --> 00:36:30,839
Speaker 1: have all these protons which are being pushed apart by

685
00:36:30,840 --> 00:36:34,440
Speaker 1: their electrical charges but being held together by the nuclear force.

686
00:36:34,719 --> 00:36:36,920
Speaker 1: As you add more neutrons in there, it helps keep

687
00:36:36,920 --> 00:36:39,360
Speaker 1: the protons further apart, so it makes it more stable.

688
00:36:39,440 --> 00:36:42,200
Speaker 1: There's a whole field of nuclear physics about understanding how

689
00:36:42,280 --> 00:36:44,440
Speaker 1: big a nucleus you can make, and which ones are

690
00:36:44,440 --> 00:36:46,920
Speaker 1: stable and which ones are not. Not something we understand.

691
00:36:46,960 --> 00:36:49,560
Speaker 1: Because the strong force is also really really hard to

692
00:36:49,600 --> 00:36:53,719
Speaker 1: do calculations with because it's so powerful, little changes in

693
00:36:53,760 --> 00:36:56,320
Speaker 1: position can totally throw off your calculation.

694
00:36:56,880 --> 00:36:58,719
Speaker 2: I mean that seems like it puts you in a

695
00:36:58,800 --> 00:37:02,680
Speaker 2: very difficult position as particle physicists and being able to

696
00:37:02,880 --> 00:37:04,640
Speaker 2: measure strong nuclear forces.

697
00:37:05,000 --> 00:37:07,080
Speaker 1: It is indeed very difficult. It's difficult to do the

698
00:37:07,080 --> 00:37:09,839
Speaker 1: theoretical calculations and difficult to make the measurements, which is

699
00:37:10,120 --> 00:37:13,560
Speaker 1: why the strong force is an enduring mystery in particle physics.

700
00:37:13,640 --> 00:37:16,480
Speaker 2: Well figure it out, you guys. What are we paying

701
00:37:16,480 --> 00:37:19,040
Speaker 2: you for? So is that it? Are there any other

702
00:37:19,400 --> 00:37:21,160
Speaker 2: forces that I should know about?

703
00:37:21,280 --> 00:37:24,240
Speaker 1: There's one more force which may not even be a force,

704
00:37:24,320 --> 00:37:27,520
Speaker 1: and that's gravity. Gravity is something we often think about

705
00:37:27,560 --> 00:37:31,480
Speaker 1: as a force colloquially, though in relativity we describe it

706
00:37:31,600 --> 00:37:35,200
Speaker 1: instead as the impact of the curvature of space time

707
00:37:35,400 --> 00:37:38,160
Speaker 1: changing the way things move and changing the relative distances

708
00:37:38,200 --> 00:37:41,360
Speaker 1: between things. But in our daily life and our experience,

709
00:37:41,360 --> 00:37:43,760
Speaker 1: we still sort of see it as a force because

710
00:37:43,760 --> 00:37:46,800
Speaker 1: we can't see that curvature of space time directly. Instead,

711
00:37:46,840 --> 00:37:49,759
Speaker 1: we just experience it as if there was a force there.

712
00:37:50,000 --> 00:37:53,520
Speaker 1: And gravity is very powerful in terms of building the universe,

713
00:37:53,600 --> 00:37:55,840
Speaker 1: like the Earth is held together because of gravity. The

714
00:37:55,840 --> 00:37:59,040
Speaker 1: whole structure of the universe is because of gravity. But

715
00:37:59,080 --> 00:38:03,200
Speaker 1: it's also dooper weak, Like you can overcome the gravity

716
00:38:03,239 --> 00:38:05,879
Speaker 1: of the Earth using the power of your muscles. Right

717
00:38:05,880 --> 00:38:07,960
Speaker 1: every time you leap off the surface of the Earth,

718
00:38:08,200 --> 00:38:12,520
Speaker 1: you were defeating an entire planet size gravitational field with

719
00:38:12,800 --> 00:38:14,440
Speaker 1: just your impressive quads.

720
00:38:14,800 --> 00:38:16,000
Speaker 2: Yeah, take that Earth.

721
00:38:17,520 --> 00:38:20,239
Speaker 1: But we don't know fundamentally if gravity is just the

722
00:38:20,239 --> 00:38:22,600
Speaker 1: curvature of space time or if it's a quantum force

723
00:38:22,719 --> 00:38:24,439
Speaker 1: like the other ones. There's a whole group of people

724
00:38:24,520 --> 00:38:27,800
Speaker 1: working on quantum gravity try to understand how to unify

725
00:38:27,920 --> 00:38:31,200
Speaker 1: gravity with the other forces for which we have quantum theories.

726
00:38:31,400 --> 00:38:35,040
Speaker 2: Yeah, and it's interesting because we can kind of feel gravity,

727
00:38:35,080 --> 00:38:38,279
Speaker 2: and I don't just mean like when you've impacted on

728
00:38:38,320 --> 00:38:40,760
Speaker 2: the ground, because you're just sort of feeling the ground

729
00:38:40,800 --> 00:38:43,759
Speaker 2: at that point, but like when you're weightless, if you've

730
00:38:43,760 --> 00:38:46,560
Speaker 2: ever been on a roller coaster or you feel kind

731
00:38:46,560 --> 00:38:48,960
Speaker 2: of weightless, it's not so much maybe that we're feeling

732
00:38:49,160 --> 00:38:53,040
Speaker 2: the gravity, but we're feeling acceleration or the lack thereof

733
00:38:53,200 --> 00:38:56,160
Speaker 2: when we're expecting it. But there's definitely sort of some

734
00:38:56,400 --> 00:39:00,680
Speaker 2: senses that we have that gravity definitely impacts.

735
00:39:00,920 --> 00:39:03,520
Speaker 1: Yeah, and we'll dig into that in a minute. And then,

736
00:39:03,560 --> 00:39:06,040
Speaker 1: of course there are forces we don't yet know about.

737
00:39:06,040 --> 00:39:08,960
Speaker 1: These are the ones we've experienced and categorized and described,

738
00:39:09,000 --> 00:39:11,640
Speaker 1: but there could be other forces out there in the universe.

739
00:39:11,920 --> 00:39:14,040
Speaker 1: Remember that most of the matter in the universe is

740
00:39:14,040 --> 00:39:15,960
Speaker 1: not the kind of matter that makes us up and

741
00:39:15,960 --> 00:39:18,960
Speaker 1: that we experience. It's dark matter, and dark matter might

742
00:39:19,040 --> 00:39:21,239
Speaker 1: have some other kind of forces that it uses to

743
00:39:21,280 --> 00:39:24,960
Speaker 1: obeying against itself that we have never experienced.

744
00:39:25,280 --> 00:39:28,440
Speaker 2: So you're saying there are like physics gremlins that we

745
00:39:28,560 --> 00:39:30,839
Speaker 2: just don't really know about.

746
00:39:31,960 --> 00:39:33,880
Speaker 1: Maybe the aliens are physics gremlins.

747
00:39:34,040 --> 00:39:36,759
Speaker 2: So we've talked about physics forces. Now I want to

748
00:39:36,800 --> 00:39:39,239
Speaker 2: talk about biology a little bit. I want to talk

749
00:39:39,280 --> 00:39:42,600
Speaker 2: about how physics interacts with our bodies.

750
00:39:42,960 --> 00:39:46,120
Speaker 1: Absolutely, let's talk about what we can sense and how

751
00:39:46,160 --> 00:39:49,040
Speaker 1: that works, how we map that to these fundamental forces.

752
00:39:49,080 --> 00:39:50,920
Speaker 1: And I think we should start with vision because to me,

753
00:39:50,960 --> 00:39:52,799
Speaker 1: it's one of the most fundamental senses. You know, it's

754
00:39:52,800 --> 00:39:55,160
Speaker 1: the way that we sort of build our model of

755
00:39:55,200 --> 00:39:57,520
Speaker 1: the world out there by looking around us and imagining

756
00:39:57,560 --> 00:39:58,560
Speaker 1: where stuff is.

757
00:39:58,880 --> 00:40:05,040
Speaker 2: Yeah, humans are interests because we are very vision focused,

758
00:40:05,160 --> 00:40:09,000
Speaker 2: I think. So vision is something that's very important to

759
00:40:09,120 --> 00:40:14,080
Speaker 2: us in terms of our socialization and our societies. And

760
00:40:14,239 --> 00:40:17,040
Speaker 2: you know, of course, like there are people who operate

761
00:40:17,120 --> 00:40:20,640
Speaker 2: without vision and they make it work, but sort of

762
00:40:20,680 --> 00:40:26,240
Speaker 2: evolutionarily speaking, vision is a very sort of fundamental sense

763
00:40:26,520 --> 00:40:30,880
Speaker 2: for human beings and how our socialization has developed, like

764
00:40:31,040 --> 00:40:33,680
Speaker 2: in terms of being able to see each other's faces,

765
00:40:34,000 --> 00:40:37,400
Speaker 2: understand each other's emotions, kind of these maps we have

766
00:40:37,520 --> 00:40:41,000
Speaker 2: in our brains of what a face should look like.

767
00:40:41,360 --> 00:40:43,360
Speaker 2: So it's really it's an interesting thing because there are

768
00:40:43,360 --> 00:40:45,480
Speaker 2: a lot of animals, There are a lot of creatures

769
00:40:45,520 --> 00:40:48,520
Speaker 2: in the world that are not as visually dependent as

770
00:40:48,600 --> 00:40:52,399
Speaker 2: humans are in terms of their sort of survival strategies.

771
00:40:52,760 --> 00:40:55,080
Speaker 1: Yeah, it's incredible sort of how we build our mental

772
00:40:55,080 --> 00:40:57,200
Speaker 1: maps of the world and how that's informed by what

773
00:40:57,239 --> 00:40:59,440
Speaker 1: we see what we don't see. But let's break it

774
00:40:59,480 --> 00:41:01,760
Speaker 1: down and think about like the journey of a photon

775
00:41:01,800 --> 00:41:05,080
Speaker 1: in terms of the fundamental physics. Of course, the photon itself,

776
00:41:05,120 --> 00:41:07,920
Speaker 1: the thing that you're seeing is a little ripple in

777
00:41:07,920 --> 00:41:11,640
Speaker 1: an electromagnetic field. It's created by an electron maybe that's

778
00:41:11,719 --> 00:41:14,480
Speaker 1: jumped down an energy level or whizzed around in the

779
00:41:14,560 --> 00:41:16,759
Speaker 1: universe and gotten bent by a field and had to

780
00:41:16,840 --> 00:41:19,799
Speaker 1: change directions. So given off a photon, that photon is

781
00:41:19,800 --> 00:41:22,520
Speaker 1: now a little pulse of energy in the electromagnetic field

782
00:41:22,520 --> 00:41:25,200
Speaker 1: wiggling through the universe at the speed of light. And

783
00:41:25,200 --> 00:41:27,919
Speaker 1: that is in the end, what we're trying to sense, right,

784
00:41:27,960 --> 00:41:30,919
Speaker 1: And so that photon then hits your eyeball, and there's

785
00:41:30,920 --> 00:41:34,279
Speaker 1: a lot of Rube Goldberg like mechanical bits that happen there.

786
00:41:34,600 --> 00:41:36,960
Speaker 1: When the photon hits your eyeball, you might say like, okay,

787
00:41:37,280 --> 00:41:40,680
Speaker 1: photon is electromagnetics, so therefore that's the force that powers it.

788
00:41:40,880 --> 00:41:42,640
Speaker 1: But you also have to dig into like how we

789
00:41:42,760 --> 00:41:46,360
Speaker 1: actually see the photon, not just what the photon itself

790
00:41:46,480 --> 00:41:47,279
Speaker 1: is made out of.

791
00:41:47,680 --> 00:41:51,760
Speaker 2: Yeah, exactly. So it's really interesting too, because our entire

792
00:41:51,920 --> 00:41:55,720
Speaker 2: eye is kind of one of the more elegant things

793
00:41:55,840 --> 00:42:00,480
Speaker 2: that evolution has produced, that there is all of these

794
00:42:00,680 --> 00:42:06,680
Speaker 2: structures that are specifically designed to be able to capture

795
00:42:07,000 --> 00:42:11,000
Speaker 2: and focus light. Of course, like we have the cornea,

796
00:42:11,400 --> 00:42:15,319
Speaker 2: which essentially like allows the light to pass through and

797
00:42:15,360 --> 00:42:18,080
Speaker 2: then it bends it and then it hits that lens

798
00:42:18,320 --> 00:42:21,920
Speaker 2: which can focus the light onto the back of the eye.

799
00:42:21,920 --> 00:42:23,800
Speaker 2: And the back of the eye is called the retina,

800
00:42:24,040 --> 00:42:27,600
Speaker 2: and the retina has all of these photoreceptors on it,

801
00:42:27,719 --> 00:42:33,280
Speaker 2: the rods and the cones. The iris is that colorful

802
00:42:33,600 --> 00:42:39,239
Speaker 2: ring around your pupil, and that focuses the constriction and

803
00:42:39,680 --> 00:42:43,719
Speaker 2: opening of the iris determines how much light is lit in.

804
00:42:44,080 --> 00:42:46,640
Speaker 2: And the pupil is not really a thing, it's the

805
00:42:46,719 --> 00:42:49,600
Speaker 2: absence of a thing. The pupil is just the hole

806
00:42:49,680 --> 00:42:52,360
Speaker 2: that leads into your eye.

807
00:42:52,840 --> 00:42:55,560
Speaker 1: Yes, you have this sort of squishy muscular sack that

808
00:42:55,640 --> 00:42:59,239
Speaker 1: controls where those photons go and how they get back

809
00:42:59,280 --> 00:43:01,840
Speaker 1: to the receptor, which is the part that's really doing

810
00:43:01,920 --> 00:43:04,880
Speaker 1: the sensing. But you can't just ignore the eyeball because

811
00:43:04,920 --> 00:43:07,600
Speaker 1: also it's a filter, right, It controls the amount of light,

812
00:43:07,640 --> 00:43:11,400
Speaker 1: so it rejects some photons. It also filters them by frequency.

813
00:43:11,480 --> 00:43:14,719
Speaker 1: Not all frequencies of light. See, the eyeball is equally transparent.

814
00:43:15,080 --> 00:43:16,799
Speaker 1: Some of them don't make it to the back of

815
00:43:16,840 --> 00:43:19,080
Speaker 1: the eyeball, and some of them do, which is why

816
00:43:19,160 --> 00:43:21,879
Speaker 1: you can and cannot see some frequencies of light.

817
00:43:22,080 --> 00:43:25,319
Speaker 2: That's right, Like, that's why we can't see UV light

818
00:43:25,520 --> 00:43:30,200
Speaker 2: generally because the cornea filters it out. That's why people

819
00:43:30,280 --> 00:43:33,320
Speaker 2: who have had surgery on their eyes where they're removing

820
00:43:33,520 --> 00:43:36,279
Speaker 2: a part of the cordia and replacing it with an

821
00:43:36,360 --> 00:43:40,960
Speaker 2: artificial cornea actually sometimes can see UV light because that

822
00:43:41,080 --> 00:43:44,200
Speaker 2: natural corneal filter is no longer there.

823
00:43:44,320 --> 00:43:47,400
Speaker 1: Wow, that's crazy, like a whole new window onto the universe.

824
00:43:47,480 --> 00:43:50,520
Speaker 1: But the actual sensing motion itself is amazing to mean,

825
00:43:50,560 --> 00:43:53,440
Speaker 1: because it's like a tiny little machine. I mean, you

826
00:43:53,480 --> 00:43:55,520
Speaker 1: imagine this whole thing is going to be electrical. They

827
00:43:55,520 --> 00:43:58,440
Speaker 1: have a pulse of electromagnetism which is then received and

828
00:43:58,480 --> 00:44:01,360
Speaker 1: turned into an electrical pulse. The nerves, et cetera, et cetera.

829
00:44:01,440 --> 00:44:03,560
Speaker 1: The whole thing's got to be electrical, right, But at

830
00:44:03,600 --> 00:44:06,840
Speaker 1: the heart of it is a little machine. These proteins,

831
00:44:06,840 --> 00:44:09,279
Speaker 1: which are fundamental building blocks of biology in the end,

832
00:44:09,400 --> 00:44:12,800
Speaker 1: are little molecular machines they like. And what a photoreceptor

833
00:44:12,800 --> 00:44:15,399
Speaker 1: fundamentally is is a protein that when a photon hits

834
00:44:15,400 --> 00:44:19,080
Speaker 1: it undergoes a conformational change. It's like it flips a

835
00:44:19,200 --> 00:44:21,799
Speaker 1: switch on this protein. It's kind of incredible to me

836
00:44:22,120 --> 00:44:23,839
Speaker 1: that the whole thing is so mechanical.

837
00:44:24,080 --> 00:44:27,960
Speaker 2: Yeah, it just kind of like snaps into place, and

838
00:44:28,280 --> 00:44:33,080
Speaker 2: that snapping is actually what causes the signal to be

839
00:44:33,160 --> 00:44:37,320
Speaker 2: sent to the nerve, and then that goes to the nerve.

840
00:44:37,560 --> 00:44:41,640
Speaker 2: Like all of these little smaller nerves collect into that

841
00:44:41,719 --> 00:44:44,360
Speaker 2: nerve bundle at the back of your eye. That's actually

842
00:44:44,360 --> 00:44:46,480
Speaker 2: where your blind spot is, and all of that goes

843
00:44:46,600 --> 00:44:49,839
Speaker 2: to the occipital lobe in your brain. But it all

844
00:44:49,880 --> 00:44:55,680
Speaker 2: starts with that snapping action of the photoreceptive cell.

845
00:44:55,920 --> 00:44:59,120
Speaker 1: It's incredible how important it is that things really move right.

846
00:44:59,200 --> 00:45:02,160
Speaker 1: We're used to thinking about solve state technology and hard

847
00:45:02,239 --> 00:45:05,000
Speaker 1: drives that don't spin is lasting longer, But in order

848
00:45:05,040 --> 00:45:07,360
Speaker 1: for you to see, you have to have these proteins

849
00:45:07,360 --> 00:45:10,000
Speaker 1: in your eye that flip back and forth. Right, they

850
00:45:10,040 --> 00:45:11,600
Speaker 1: flip when they get hit by a photon, and they

851
00:45:11,600 --> 00:45:14,240
Speaker 1: flip back quickly so you can see a new picture.

852
00:45:14,360 --> 00:45:17,320
Speaker 1: It's like having all these little mechanical shutters worrying inside

853
00:45:17,320 --> 00:45:18,760
Speaker 1: your eyeball at all times.

854
00:45:19,080 --> 00:45:22,520
Speaker 2: And depending on the type of cell, it responds to

855
00:45:23,000 --> 00:45:25,600
Speaker 2: the different wavelengths of light. So that's how we can

856
00:45:25,640 --> 00:45:30,040
Speaker 2: distinguish color, right, Like, if we didn't have that ability

857
00:45:30,080 --> 00:45:33,040
Speaker 2: to distinguish between wavelengths of light, we can only kind

858
00:45:33,080 --> 00:45:36,359
Speaker 2: of understand whether there's light or not. But because they

859
00:45:36,400 --> 00:45:40,920
Speaker 2: are specifically able to have that snapping movement to maybe

860
00:45:41,040 --> 00:45:44,239
Speaker 2: red light to green light, to blue light, or some

861
00:45:44,440 --> 00:45:48,520
Speaker 2: combination of that, like some sensitivity, it's usually on a spectrum.

862
00:45:48,600 --> 00:45:51,839
Speaker 2: That's how we are able to not only be able

863
00:45:51,880 --> 00:45:55,839
Speaker 2: to tell the difference between those types of wavelengths of light,

864
00:45:56,080 --> 00:45:59,959
Speaker 2: but to build a complex repertoire of a whole gray

865
00:46:00,640 --> 00:46:04,279
Speaker 2: of light, like we could in theory see like an

866
00:46:04,320 --> 00:46:09,600
Speaker 2: almost infinite combination of different types of wavelengths hitting our

867
00:46:09,600 --> 00:46:13,319
Speaker 2: eyes causing that reaction, and then our brain is the

868
00:46:13,440 --> 00:46:16,840
Speaker 2: thing that calculates like what we actually see, how we

869
00:46:16,880 --> 00:46:21,680
Speaker 2: actually interpret that color. But it's thanks to this mechanical

870
00:46:22,120 --> 00:46:26,560
Speaker 2: ability of those cells to respond differently to different wavelengths

871
00:46:26,560 --> 00:46:28,919
Speaker 2: of light. And so you'll have a cell that does

872
00:46:28,960 --> 00:46:33,680
Speaker 2: not respond to a longer wavelength of light, but that

873
00:46:33,760 --> 00:46:37,200
Speaker 2: same cell responds to a shorter wavelength of light, or

874
00:46:37,239 --> 00:46:40,600
Speaker 2: a different cell that only responds to longer wavelengths of light.

875
00:46:40,680 --> 00:46:44,240
Speaker 2: So it's that combination of those differentiated cells that allows

876
00:46:44,280 --> 00:46:45,840
Speaker 2: you to see complex color.

877
00:46:45,960 --> 00:46:49,000
Speaker 1: Yeah, it's sort of like frequency triangulation. You can figure

878
00:46:49,000 --> 00:46:51,480
Speaker 1: out by understanding how much each of them was triggered

879
00:46:51,840 --> 00:46:54,440
Speaker 1: where the real frequency was, which gives you the ability

880
00:46:54,480 --> 00:46:58,120
Speaker 1: to sense the infinite spectrum of photons. But even though

881
00:46:58,120 --> 00:46:59,959
Speaker 1: it is mechanical, even though you have all these little

882
00:47:00,120 --> 00:47:03,120
Speaker 1: machines worrying inside your eyeball all the time, which if

883
00:47:03,120 --> 00:47:05,319
Speaker 1: you're really quiet, maybe you could listen to and hear,

884
00:47:05,560 --> 00:47:09,200
Speaker 1: in the end, it is still electro mechanical because all

885
00:47:09,239 --> 00:47:12,719
Speaker 1: these things are chemical, like the protein structures and the

886
00:47:12,760 --> 00:47:15,000
Speaker 1: way the protein moves, the way a respond to the

887
00:47:15,040 --> 00:47:18,800
Speaker 1: photon is in the end, all because of the atomic bonds.

888
00:47:19,000 --> 00:47:21,040
Speaker 1: The way these proteins are built, the way they can

889
00:47:21,080 --> 00:47:23,880
Speaker 1: settle into various states, all come down to how the

890
00:47:23,960 --> 00:47:27,439
Speaker 1: atoms inside those protons are bonded with each other where

891
00:47:27,440 --> 00:47:29,719
Speaker 1: they like to be, where the lowest energy states are.

892
00:47:29,960 --> 00:47:32,480
Speaker 1: And that's all due to the atomic bonds which comes

893
00:47:32,520 --> 00:47:35,920
Speaker 1: from the electron the whizzing around between these nuclei. So

894
00:47:35,960 --> 00:47:38,640
Speaker 1: in the end, the entire chain here really is just

895
00:47:38,760 --> 00:47:40,640
Speaker 1: due to electromagnetism.

896
00:47:41,040 --> 00:47:44,840
Speaker 2: It's like an even tinier Roob Goldberg machine inside of

897
00:47:44,840 --> 00:47:48,680
Speaker 2: the tiny Roob Goldberg machine's Roob Goldberg machines all the

898
00:47:48,680 --> 00:47:51,000
Speaker 2: way down, which is a hard thing to say. The

899
00:47:51,040 --> 00:47:53,720
Speaker 2: words don't come out of my mouth very well.

900
00:47:53,920 --> 00:47:57,279
Speaker 1: So it's a pulso electromagnetism which then gets converted via

901
00:47:57,360 --> 00:48:00,279
Speaker 1: a little machine which is built on electromagnetism, into an

902
00:48:00,280 --> 00:48:02,920
Speaker 1: electromagnetic pulse in your nerves. So it's sort of like

903
00:48:02,920 --> 00:48:05,080
Speaker 1: a Rube Goldberg zapping machine, right.

904
00:48:05,120 --> 00:48:07,440
Speaker 2: And then once it hits your brain, of course, the

905
00:48:07,800 --> 00:48:11,400
Speaker 2: electromagnetic elements of the brain, it is the pattern of

906
00:48:11,480 --> 00:48:15,239
Speaker 2: the synapses firing. You have some kind of difference in

907
00:48:15,320 --> 00:48:19,440
Speaker 2: electrical potential between two neurons and then that causes firing

908
00:48:19,520 --> 00:48:24,360
Speaker 2: across the synapse of transfer neurotransmitters, and it's that pattern

909
00:48:24,680 --> 00:48:29,439
Speaker 2: of firing that gives you the conscious experience of the.

910
00:48:29,360 --> 00:48:32,400
Speaker 1: Color exactly, and your whole visual experience of the world

911
00:48:32,760 --> 00:48:37,680
Speaker 1: rests on electromagnetism. Without those electrons and their little magnetic properties,

912
00:48:37,840 --> 00:48:39,080
Speaker 1: you couldn't see anything.

913
00:48:39,480 --> 00:48:45,160
Speaker 2: I feel like this is a commercial for electromagnetism. Electromagnetism,

914
00:48:45,280 --> 00:48:46,879
Speaker 2: you couldn't do anything without it.

915
00:48:48,280 --> 00:48:50,280
Speaker 1: I am indeed a shill for big electron.

916
00:48:50,640 --> 00:48:53,080
Speaker 2: Well, we are going to take a quick break, but

917
00:48:53,160 --> 00:48:55,520
Speaker 2: you know what, we couldn't have taken a quick break

918
00:48:55,600 --> 00:49:14,399
Speaker 2: without electromagnetism. So here's a word from our sponsor, electromagnetism.

919
00:49:14,480 --> 00:49:17,040
Speaker 2: All right, so we are back. I hope you've all

920
00:49:17,320 --> 00:49:21,759
Speaker 2: purchased a big box of electromagnetism. I don't even know

921
00:49:21,800 --> 00:49:24,520
Speaker 2: what that would look like, a bunch of magnets and

922
00:49:24,600 --> 00:49:28,400
Speaker 2: light bulbs something. But yeah, let's talk about more senses

923
00:49:28,719 --> 00:49:33,080
Speaker 2: and how they work, how this complex dance between the

924
00:49:33,120 --> 00:49:36,600
Speaker 2: world of the physical and then our brains and our

925
00:49:36,680 --> 00:49:39,200
Speaker 2: sensory organs kind of interact.

926
00:49:39,320 --> 00:49:41,680
Speaker 1: Yeah, let's see if we can escape the little electromagnetic

927
00:49:41,680 --> 00:49:45,120
Speaker 1: grimlins and find out if other forces play important roles

928
00:49:45,160 --> 00:49:47,600
Speaker 1: in our senses in the universe. And maybe next we

929
00:49:47,680 --> 00:49:49,879
Speaker 1: should talk about the one that you're experiencing right now,

930
00:49:49,920 --> 00:49:53,000
Speaker 1: the one you're using to hear our voices. Sound. What

931
00:49:53,160 --> 00:49:56,279
Speaker 1: sound is and how we experience it. Sound waves are

932
00:49:56,440 --> 00:49:59,919
Speaker 1: just molecules bumping into each other. Soundwaves are not fun

933
00:50:00,200 --> 00:50:02,719
Speaker 1: mental properties of the universe. The way a photon is

934
00:50:02,760 --> 00:50:05,840
Speaker 1: a photon is a ripple in the electromagnetic field, a

935
00:50:05,960 --> 00:50:08,720
Speaker 1: sound wave is a ripple in something else that already

936
00:50:08,719 --> 00:50:11,719
Speaker 1: exists in the universe, matter in the universe. So if

937
00:50:11,760 --> 00:50:14,280
Speaker 1: you imagine like a table filled with ping pong balls

938
00:50:14,320 --> 00:50:16,760
Speaker 1: and you push on the ping pong balls on your side,

939
00:50:16,800 --> 00:50:18,680
Speaker 1: they're gonna push on the next set of ping pong ball,

940
00:50:18,760 --> 00:50:21,160
Speaker 1: to push on the next set, and eventually they'll fall

941
00:50:21,200 --> 00:50:23,920
Speaker 1: off the other side of the table. So sound is

942
00:50:23,920 --> 00:50:26,799
Speaker 1: really just like that. It's pressure waves in air or

943
00:50:26,840 --> 00:50:29,480
Speaker 1: in metal, or in water, or in any kind of

944
00:50:29,640 --> 00:50:33,200
Speaker 1: matter that squeeze together as bonded enough together for one

945
00:50:33,239 --> 00:50:34,799
Speaker 1: bit to push on another bit.

946
00:50:35,160 --> 00:50:37,880
Speaker 2: It's like a Newton's cradle and then the final ball

947
00:50:38,000 --> 00:50:42,959
Speaker 2: sor it's inside your ear, the little delicate organs that

948
00:50:43,320 --> 00:50:44,640
Speaker 2: help you experience sound.

949
00:50:44,960 --> 00:50:48,040
Speaker 1: And that's why sound requires some kind of matter medium. Right,

950
00:50:48,120 --> 00:50:50,680
Speaker 1: you can't have sound in a perfect vacuum because there's

951
00:50:50,760 --> 00:50:54,120
Speaker 1: nothing to push whereas you could have photons because photons

952
00:50:54,160 --> 00:50:58,520
Speaker 1: are ripples in the fundamental electromagnetic fields, which are always there,

953
00:50:58,600 --> 00:51:01,120
Speaker 1: no matter how much stuff you suck out of your chamber.

954
00:51:01,400 --> 00:51:04,120
Speaker 2: So when they say that there's no sound in space,

955
00:51:04,920 --> 00:51:07,680
Speaker 2: there's really no sound. Like It's not like if a

956
00:51:07,719 --> 00:51:10,280
Speaker 2: tree falls in a forest and no one's around, it's like, well,

957
00:51:10,840 --> 00:51:14,279
Speaker 2: it does make a sound because it is pushing the

958
00:51:14,320 --> 00:51:17,920
Speaker 2: air around it. So technically, if what we're calling sound

959
00:51:18,040 --> 00:51:22,560
Speaker 2: is the wave of molecules bonking into each other, it

960
00:51:22,600 --> 00:51:24,920
Speaker 2: does exist in a forest, but it really does not

961
00:51:25,040 --> 00:51:25,920
Speaker 2: exist in space.

962
00:51:26,280 --> 00:51:28,840
Speaker 1: Yeah, physics would say that pressure waves are created in

963
00:51:28,880 --> 00:51:31,000
Speaker 1: the air when a tree falls in the forest, but

964
00:51:31,080 --> 00:51:34,720
Speaker 1: it doesn't impact anybody's sensors. Is it really a sound

965
00:51:34,880 --> 00:51:36,640
Speaker 1: or is it just pressure waves? I think that's the

966
00:51:36,680 --> 00:51:39,719
Speaker 1: philosophical question, but the physics question for space. Actually, the

967
00:51:39,719 --> 00:51:42,720
Speaker 1: answer is that sound does exist in outer space because

968
00:51:42,760 --> 00:51:45,919
Speaker 1: space is not a vacuum. There are particles out there,

969
00:51:45,920 --> 00:51:50,520
Speaker 1: electrons and protons constantly whizzing around. Now much much lower density,

970
00:51:50,560 --> 00:51:53,239
Speaker 1: of course than anything we experience on Earth, but there

971
00:51:53,280 --> 00:51:55,440
Speaker 1: are particles out there, and you can push on them,

972
00:51:55,440 --> 00:51:58,960
Speaker 1: and you can make pressure waves in the solar wind,

973
00:51:59,000 --> 00:52:02,360
Speaker 1: for example, So technically there is sound in outer space,

974
00:52:02,640 --> 00:52:04,840
Speaker 1: so feel free to scream if you're attacked by the

975
00:52:04,840 --> 00:52:07,480
Speaker 1: electromagnetic gremlins on your next space voyage.

976
00:52:07,560 --> 00:52:09,640
Speaker 2: So did Star Wars lie to me or not?

977
00:52:10,280 --> 00:52:12,840
Speaker 1: The question? The answer to that is definitely yes. No

978
00:52:12,880 --> 00:52:15,759
Speaker 1: matter what we're talking about. Star Wars is a big lie.

979
00:52:16,400 --> 00:52:18,360
Speaker 1: We've got the force, we've got lightsabers, I mean, the

980
00:52:18,400 --> 00:52:21,280
Speaker 1: whole thing is just magical realism. I love it, of course,

981
00:52:21,360 --> 00:52:23,640
Speaker 1: but it's a big lie. So in terms of how

982
00:52:23,680 --> 00:52:26,800
Speaker 1: we perceive sound, right, we know sound are pressure waves

983
00:52:26,800 --> 00:52:31,080
Speaker 1: through the air, and we've developed these biomechanical abilities to

984
00:52:31,239 --> 00:52:34,440
Speaker 1: sense this. And the ear is basically like a complex

985
00:52:34,560 --> 00:52:38,560
Speaker 1: instrument for focusing and transmitting that energy into a mechanism

986
00:52:38,560 --> 00:52:41,480
Speaker 1: that your brain can perceive. And there's various parts of

987
00:52:41,520 --> 00:52:45,400
Speaker 1: the ear. It's really incredibly complicated. The outer ear focuses

988
00:52:45,400 --> 00:52:48,680
Speaker 1: the sound waves towards the ear drum, which then vibrates. Right,

989
00:52:48,760 --> 00:52:51,560
Speaker 1: you have this like literal drum inside your ear that's

990
00:52:51,640 --> 00:52:54,759
Speaker 1: vibrating at the same frequency as these pressure waves. And

991
00:52:54,800 --> 00:52:56,600
Speaker 1: you might think, oh, well, that's it. You have an

992
00:52:56,640 --> 00:52:58,960
Speaker 1: ear drum and it's vibrating, You're done. But that's just

993
00:52:59,000 --> 00:52:59,640
Speaker 1: like step one.

994
00:52:59,760 --> 00:53:02,200
Speaker 2: Right, And this is also why you do not use

995
00:53:02,280 --> 00:53:05,239
Speaker 2: Q tips in your ear, because it is a literal physical,

996
00:53:05,719 --> 00:53:10,200
Speaker 2: stretchy membrane, but it's very delicate, and it needs to

997
00:53:10,200 --> 00:53:13,400
Speaker 2: be very delicate to pick up on these very like

998
00:53:13,560 --> 00:53:17,319
Speaker 2: minute vibrations because we can hear soft sounds as well

999
00:53:17,360 --> 00:53:20,160
Speaker 2: as loud sounds, so it's got to be sensitive to that.

1000
00:53:20,320 --> 00:53:22,600
Speaker 1: So you should always clean your ear drum with a squeegee.

1001
00:53:22,640 --> 00:53:26,480
Speaker 2: Right exactly, you shove a cue tip in too far,

1002
00:53:26,600 --> 00:53:29,080
Speaker 2: you'll actually puncture that ear drum.

1003
00:53:29,200 --> 00:53:30,279
Speaker 1: Oh please don't do that.

1004
00:53:30,480 --> 00:53:34,480
Speaker 2: Yeah, please don't do that. Don't I'm saying not to

1005
00:53:34,560 --> 00:53:35,239
Speaker 2: do that, And.

1006
00:53:35,280 --> 00:53:37,080
Speaker 1: Yet you're giving me a mental image of it happening,

1007
00:53:37,160 --> 00:53:38,080
Speaker 1: which is making me show.

1008
00:53:40,920 --> 00:53:44,400
Speaker 2: So we've shrunk down real tiny, and we're inside your ears.

1009
00:53:45,280 --> 00:53:48,360
Speaker 2: We've found the ear drum, Like what else are we

1010
00:53:48,400 --> 00:53:49,360
Speaker 2: going to find in here?

1011
00:53:49,520 --> 00:53:51,600
Speaker 1: So then in the middle ear, we have these three

1012
00:53:51,760 --> 00:53:56,239
Speaker 1: tiny little bones which basically help transmit those vibrations from

1013
00:53:56,239 --> 00:53:59,319
Speaker 1: the outer ear to the inner ear. And this is

1014
00:53:59,320 --> 00:54:02,480
Speaker 1: a little bit of an engineering called impedance matching. If

1015
00:54:02,480 --> 00:54:05,760
Speaker 1: you want a signal to get transmitted across different kinds

1016
00:54:05,760 --> 00:54:09,080
Speaker 1: of materials without complicated reflections. Then you have to be

1017
00:54:09,120 --> 00:54:11,879
Speaker 1: really careful about how that interface happens so you don't

1018
00:54:11,880 --> 00:54:14,120
Speaker 1: get all sorts of lostiness and reflections which you can

1019
00:54:14,200 --> 00:54:16,799
Speaker 1: echo back on each other. So these are engineered to

1020
00:54:16,800 --> 00:54:20,200
Speaker 1: sort of transform the waves from the ear drum into

1021
00:54:20,280 --> 00:54:23,520
Speaker 1: the inner ear, which has this little tube filled with

1022
00:54:23,640 --> 00:54:26,960
Speaker 1: fluid which can then vibrate. So it's really complicated process

1023
00:54:27,000 --> 00:54:29,719
Speaker 1: with these ear drum and then these three tiny bones,

1024
00:54:30,040 --> 00:54:32,760
Speaker 1: and then finally in the end it's this little spiral,

1025
00:54:32,880 --> 00:54:35,600
Speaker 1: fluid filled tube that you want to vibrate so that

1026
00:54:35,640 --> 00:54:37,000
Speaker 1: you can actually hear something.

1027
00:54:37,360 --> 00:54:41,680
Speaker 2: That's so cool. I mean, in the complexity of the ear,

1028
00:54:42,320 --> 00:54:46,600
Speaker 2: I think can also help us understand where a sound

1029
00:54:46,719 --> 00:54:49,560
Speaker 2: is coming from, like is it coming from behind us?

1030
00:54:49,920 --> 00:54:52,319
Speaker 2: Is it coming from right next to us. We have

1031
00:54:52,800 --> 00:54:55,480
Speaker 2: not just a sense of sound, but a sense of

1032
00:54:55,520 --> 00:54:59,759
Speaker 2: the location of the sound, which is really interesting. In fact,

1033
00:55:00,080 --> 00:55:04,279
Speaker 2: in owls, they have a really unique thing where their

1034
00:55:04,400 --> 00:55:06,680
Speaker 2: ear holes. They don't really have the external ears that

1035
00:55:06,800 --> 00:55:10,719
Speaker 2: humans have, but they have ear holes and one ear

1036
00:55:10,719 --> 00:55:13,799
Speaker 2: hole is actually lower than the other, so they're not symmetrical,

1037
00:55:14,200 --> 00:55:18,080
Speaker 2: and that's to help them specifically be able to tell

1038
00:55:18,600 --> 00:55:21,799
Speaker 2: where sound is coming from. When they are scanning for

1039
00:55:21,840 --> 00:55:26,920
Speaker 2: a sound coming from the ground, because then the difference

1040
00:55:27,040 --> 00:55:30,600
Speaker 2: in where the sound hits like their ear holes helps

1041
00:55:30,640 --> 00:55:33,560
Speaker 2: them triangulate very specifically. Like if they hear a little

1042
00:55:33,600 --> 00:55:36,640
Speaker 2: mouse in a field, they have to triangulate exactly where

1043
00:55:36,640 --> 00:55:39,920
Speaker 2: that mouse is, and having that difference in locations of

1044
00:55:40,000 --> 00:55:43,319
Speaker 2: the ear holes gives them yet another sort of mathematical

1045
00:55:43,360 --> 00:55:46,440
Speaker 2: calculation that their brain can do of this difference of

1046
00:55:46,480 --> 00:55:49,000
Speaker 2: the sound hitting each ear hole, and then they can

1047
00:55:49,040 --> 00:55:51,840
Speaker 2: triangulate where the tasty mouse is and grab it.

1048
00:55:52,040 --> 00:55:54,600
Speaker 1: Yeah, the key is always having different sensors with different

1049
00:55:54,640 --> 00:55:57,879
Speaker 1: capacities allows you to triangulate, and that's fascinating. But every

1050
00:55:57,880 --> 00:56:00,520
Speaker 1: time you say ear holes, it makes me wonder if

1051
00:56:00,520 --> 00:56:03,080
Speaker 1: that's like a big insult that owls use on each other,

1052
00:56:03,200 --> 00:56:04,840
Speaker 1: like they call each other ear holes.

1053
00:56:05,280 --> 00:56:07,120
Speaker 2: You're a real ear hole, Frank.

1054
00:56:07,800 --> 00:56:12,800
Speaker 1: You ate that little mouse and I totally called it.

1055
00:56:12,840 --> 00:56:15,319
Speaker 1: So you have this little spiral, fluid filled tube which

1056
00:56:15,360 --> 00:56:18,520
Speaker 1: is vibrating with the sounds which were created when Katie

1057
00:56:18,520 --> 00:56:22,000
Speaker 1: screamed in space. How do you actually experience that in

1058
00:56:22,040 --> 00:56:24,400
Speaker 1: your brain? Well, there's one more step, which is that

1059
00:56:24,440 --> 00:56:27,240
Speaker 1: there are these little hairs that wiggle and the hairs

1060
00:56:27,239 --> 00:56:30,000
Speaker 1: are in different places in this tube, and the tube

1061
00:56:30,000 --> 00:56:33,680
Speaker 1: is designed so that the sound frequencies will resonate in

1062
00:56:33,760 --> 00:56:36,920
Speaker 1: different parts of the tube. So a certain frequency, like

1063
00:56:36,920 --> 00:56:40,239
Speaker 1: the really highest sounds in Katie's scream, will land in

1064
00:56:40,280 --> 00:56:43,520
Speaker 1: a different place than this tube than the lower frequencies.

1065
00:56:43,560 --> 00:56:45,799
Speaker 1: When she's like mostly given up, the ghost will land

1066
00:56:45,840 --> 00:56:48,520
Speaker 1: in a different spot. And so different hairs get wiggled

1067
00:56:48,800 --> 00:56:52,080
Speaker 1: by different frequencies, and then that sends signals to your brain.

1068
00:56:52,160 --> 00:56:55,040
Speaker 1: The different hairs send different signals, and your brain is like, oh,

1069
00:56:55,040 --> 00:56:58,439
Speaker 1: that was a lower frequency scream or a higher frequency scream.

1070
00:56:58,480 --> 00:57:02,080
Speaker 2: Right, And the difference is ear structure based on what

1071
00:57:02,600 --> 00:57:06,480
Speaker 2: animal you are determines whether you can hear higher or

1072
00:57:06,600 --> 00:57:10,720
Speaker 2: lower frequency, Like elephants are really good at hearing really

1073
00:57:10,760 --> 00:57:14,560
Speaker 2: low frequencies that we cannot hear with our dinky little

1074
00:57:14,600 --> 00:57:17,960
Speaker 2: human ears, and dogs can hear higher frequencies that we

1075
00:57:18,000 --> 00:57:20,520
Speaker 2: cannot hear with Like if you have a dog whistle

1076
00:57:20,680 --> 00:57:24,160
Speaker 2: not talking about someone doing something naughty and pretending not

1077
00:57:24,320 --> 00:57:28,040
Speaker 2: to it's like the very high frequency sound, your dog

1078
00:57:28,080 --> 00:57:31,560
Speaker 2: will hear it and we won't. Younger people will hear

1079
00:57:31,600 --> 00:57:35,640
Speaker 2: higher frequency than older people because older people after we

1080
00:57:35,720 --> 00:57:40,000
Speaker 2: go to enough rock concerts, we start to become less

1081
00:57:40,040 --> 00:57:43,400
Speaker 2: sensitive to high frequency sound because of damage we've actually

1082
00:57:43,440 --> 00:57:44,560
Speaker 2: done to our ears.

1083
00:57:44,840 --> 00:57:47,040
Speaker 1: It's sort of the opposite of what happens in a band.

1084
00:57:47,560 --> 00:57:50,440
Speaker 1: Like the bigger instruments like the tuba can make deeper

1085
00:57:50,440 --> 00:57:53,520
Speaker 1: sounds because they physically have to be larger to contain

1086
00:57:53,560 --> 00:57:57,520
Speaker 1: the longer wavelength resonance modes there, and the little piccolo

1087
00:57:57,640 --> 00:58:00,320
Speaker 1: like the mini flute, is super duper kind, so it

1088
00:58:00,320 --> 00:58:04,000
Speaker 1: can get to those really high sounds which have shorter wavelengths.

1089
00:58:04,000 --> 00:58:07,040
Speaker 1: In the same way, bigger ears can hear deeper sounds

1090
00:58:07,120 --> 00:58:10,240
Speaker 1: lower wavelengths, and tiny ears can hear higher sounds at

1091
00:58:10,320 --> 00:58:13,320
Speaker 1: higher frequencies. So these hairs wiggle and then they're transmitted

1092
00:58:13,320 --> 00:58:15,760
Speaker 1: into nerve pulses, which is like the fundamental language of

1093
00:58:15,760 --> 00:58:18,360
Speaker 1: how your brain works. So now we have the whole chain, right.

1094
00:58:18,520 --> 00:58:21,040
Speaker 1: The scream happens in outer space, It creates a pressure

1095
00:58:21,080 --> 00:58:24,440
Speaker 1: wave which then gets transformed into different kinds of pressure

1096
00:58:24,440 --> 00:58:27,320
Speaker 1: waves in different parts of your ear, which eventually wiggle

1097
00:58:27,360 --> 00:58:30,200
Speaker 1: those hairs and send a nervous pulse up to your brain.

1098
00:58:30,800 --> 00:58:33,240
Speaker 1: And so in the end, it's all mechanical. Right. Sound

1099
00:58:33,360 --> 00:58:35,480
Speaker 1: is mechanical all to the very very end when it

1100
00:58:35,480 --> 00:58:39,160
Speaker 1: gets transformed into a nervous pulse. But that mechanical interaction

1101
00:58:39,280 --> 00:58:43,000
Speaker 1: in the end is still electromagnetic because how does the

1102
00:58:43,120 --> 00:58:46,560
Speaker 1: machine work. It's no different than those photoreceptors in your eyes,

1103
00:58:46,600 --> 00:58:49,880
Speaker 1: which are little machines. They're built out of electrons, out

1104
00:58:49,920 --> 00:58:52,440
Speaker 1: of atoms. The way they push against each other are

1105
00:58:52,480 --> 00:58:55,880
Speaker 1: electrical forces. Like we started off talking about pingpong balls

1106
00:58:55,880 --> 00:58:58,120
Speaker 1: pushing on each other, how does that happen? How does

1107
00:58:58,160 --> 00:59:01,919
Speaker 1: one air molecule push against another air molecule. Their electrons

1108
00:59:01,960 --> 00:59:04,760
Speaker 1: are repelling each other when they get too close. How

1109
00:59:04,800 --> 00:59:06,960
Speaker 1: does your chair hold you up when you sit on it.

1110
00:59:06,960 --> 00:59:10,320
Speaker 1: It's the mesh of electrical forces holding it together. So

1111
00:59:10,400 --> 00:59:13,000
Speaker 1: the atomic structure which is used to build all of

1112
00:59:13,040 --> 00:59:16,440
Speaker 1: these machines is the fundamental force that allows sound to

1113
00:59:16,480 --> 00:59:19,560
Speaker 1: be transmitted through the universe into your ear holes.

1114
00:59:20,000 --> 00:59:23,000
Speaker 2: So whether it's two ping pong balls hitting each other,

1115
00:59:23,320 --> 00:59:27,320
Speaker 2: or molecules moving through the air and hitting this complex

1116
00:59:27,360 --> 00:59:30,000
Speaker 2: structure inside of your ear, those are both things to

1117
00:59:30,400 --> 00:59:31,720
Speaker 2: electromagnetic forces.

1118
00:59:32,080 --> 00:59:35,600
Speaker 1: Absolutely, it's all electromagnetic forces that constructs the world that

1119
00:59:35,640 --> 00:59:39,000
Speaker 1: we live in and allows machines to have a physical

1120
00:59:39,080 --> 00:59:42,200
Speaker 1: extent and transmit forces to each other. And that's really

1121
00:59:42,200 --> 00:59:45,760
Speaker 1: what sound is. All of mechanical engineering really is electrical.

1122
00:59:45,280 --> 00:59:51,200
Speaker 2: Engineering, speaking of physical things bonking into each other. I

1123
00:59:51,240 --> 00:59:56,560
Speaker 2: believe probably the same force might be behind what happens

1124
00:59:56,600 --> 01:00:00,240
Speaker 2: in the inner ear in terms of your sense of

1125
01:00:00,400 --> 01:00:04,400
Speaker 2: balance and acceleration and gravity. It's like why you get

1126
01:00:04,440 --> 01:00:08,560
Speaker 2: motion sick, why you feel vertigo or a sense of

1127
01:00:08,800 --> 01:00:11,240
Speaker 2: lack of balance, like when you feel slightly off balance.

1128
01:00:11,880 --> 01:00:17,080
Speaker 2: Inside these fluid filled chambers in your ear, there's a liquid,

1129
01:00:17,120 --> 01:00:22,320
Speaker 2: but suspended in the liquid are actually these tiny calcium

1130
01:00:22,400 --> 01:00:27,080
Speaker 2: crystals that can When the movement of these crystals and

1131
01:00:27,200 --> 01:00:32,320
Speaker 2: interaction with these tiny nerves, that information is sent to

1132
01:00:32,360 --> 01:00:35,400
Speaker 2: your brain and it tells you like, hey, I'm moving,

1133
01:00:35,600 --> 01:00:39,000
Speaker 2: I'm accelerating. I'm on a roller coaster. Oh no, i

1134
01:00:39,040 --> 01:00:42,480
Speaker 2: hate roller coasters. So like, the ear not only is

1135
01:00:42,680 --> 01:00:47,840
Speaker 2: a complex sound detector, it is also a movement kind

1136
01:00:47,840 --> 01:00:51,360
Speaker 2: of like gravity and acceleration detector, which is really cool.

1137
01:00:51,560 --> 01:00:55,360
Speaker 1: Yes, absolutely, the ear is capable of measuring acceleration right

1138
01:00:55,360 --> 01:00:57,720
Speaker 1: as these crystals move to the liquid, or as the

1139
01:00:57,760 --> 01:01:01,000
Speaker 1: liquid slashes around inside your ear and touches different parts

1140
01:01:01,000 --> 01:01:03,200
Speaker 1: of it. Your brain can tell that you're being accelerator

1141
01:01:03,280 --> 01:01:05,160
Speaker 1: or you're upside down. It's sort of like if you

1142
01:01:05,240 --> 01:01:07,800
Speaker 1: had a ball inside the back of a truck. When

1143
01:01:07,800 --> 01:01:10,480
Speaker 1: you hit the acceleration on the truck, then the ball

1144
01:01:10,520 --> 01:01:12,280
Speaker 1: gets left behind, it hits the back of the truck.

1145
01:01:12,320 --> 01:01:14,240
Speaker 1: When you hit the brakes on the truck, the ball

1146
01:01:14,280 --> 01:01:16,600
Speaker 1: will roll towards the front of the truck bed. If

1147
01:01:16,640 --> 01:01:18,720
Speaker 1: you're inside the bed of the truck, you can tell

1148
01:01:18,800 --> 01:01:20,880
Speaker 1: when the gas is being pressed and when the brake

1149
01:01:20,960 --> 01:01:23,280
Speaker 1: is being pressed just by watching the ball. In the

1150
01:01:23,280 --> 01:01:25,520
Speaker 1: inner part of your ear basically works like that, and

1151
01:01:25,560 --> 01:01:28,360
Speaker 1: it allows you to measure acceleration and gravity and what's

1152
01:01:28,480 --> 01:01:31,120
Speaker 1: up and what's down. And that raised an interesting question

1153
01:01:31,240 --> 01:01:33,800
Speaker 1: like what's the fundamental force involved there. We know there

1154
01:01:33,800 --> 01:01:37,040
Speaker 1: are electromagnetic signals, and we know that the structure of

1155
01:01:37,080 --> 01:01:39,040
Speaker 1: the inner ear and all the things that it works

1156
01:01:39,040 --> 01:01:42,040
Speaker 1: on our little machines that are built with electromagnetic forces.

1157
01:01:42,400 --> 01:01:45,040
Speaker 1: But in the end, it's sensing gravity, right, It's sensing

1158
01:01:45,080 --> 01:01:48,720
Speaker 1: acceleration and motion, and so that's an interesting combination like

1159
01:01:48,760 --> 01:01:51,160
Speaker 1: gravity I think really does play a role there. We're

1160
01:01:51,240 --> 01:01:55,760
Speaker 1: using electromagnetics based sensors to observe gravity and acceleration.

1161
01:01:56,200 --> 01:02:00,040
Speaker 2: Yeah, it's so interesting. It's that like, gravity is this

1162
01:02:00,960 --> 01:02:03,280
Speaker 2: unique thing in the universe that may not even be

1163
01:02:03,320 --> 01:02:07,760
Speaker 2: a force, and yet we still have an ability to

1164
01:02:07,800 --> 01:02:11,280
Speaker 2: detect it with our ears. We've evolved this complex system

1165
01:02:11,320 --> 01:02:16,040
Speaker 2: that is basically an accelerometer like inside of our heads.

1166
01:02:16,520 --> 01:02:19,439
Speaker 1: It's amazing and very useful. And if it ever gets

1167
01:02:19,440 --> 01:02:22,160
Speaker 1: messed up while the world feels like an unpleasant.

1168
01:02:21,680 --> 01:02:26,000
Speaker 2: Place, yeah, that is like a dysfunction of those like

1169
01:02:26,040 --> 01:02:30,240
Speaker 2: little ear crystals is thought to be behind disorders like vertigo.

1170
01:02:30,480 --> 01:02:33,040
Speaker 2: I feel like we've covered the ears, not literally covered

1171
01:02:33,040 --> 01:02:35,160
Speaker 2: the ears, because you still want to hear this podcast.

1172
01:02:35,720 --> 01:02:38,520
Speaker 2: But let's talk a little bit about smell, because I'm

1173
01:02:38,520 --> 01:02:41,600
Speaker 2: smelling that chicken. I do want to go to dinner,

1174
01:02:41,960 --> 01:02:44,640
Speaker 2: but I first want to learn about how smell works.

1175
01:02:45,000 --> 01:02:48,280
Speaker 1: Smell is super fascinating because in some ways it's much

1176
01:02:48,320 --> 01:02:51,160
Speaker 1: more mechanical than the other senses, but it's also much

1177
01:02:51,200 --> 01:02:54,640
Speaker 1: more complicated. Like sound and vision in the ends can

1178
01:02:54,720 --> 01:02:58,240
Speaker 1: be expressed as observing different frequencies of the same thing,

1179
01:02:58,640 --> 01:03:01,320
Speaker 1: So you can boil it down to information, right, like

1180
01:03:01,320 --> 01:03:03,680
Speaker 1: what frequencies of light are you seeing? What frequencies of

1181
01:03:03,760 --> 01:03:06,280
Speaker 1: sound are you hearing. You can look at the equalizer

1182
01:03:06,320 --> 01:03:08,600
Speaker 1: on your stereo see like the fundamental building blocks of

1183
01:03:08,640 --> 01:03:10,480
Speaker 1: the song that you're hearing, and so it can be

1184
01:03:10,520 --> 01:03:12,640
Speaker 1: digitized and it can be transmitted. You can have like

1185
01:03:12,680 --> 01:03:17,080
Speaker 1: electronic vision and hearing right microphones and cameras and screens

1186
01:03:17,120 --> 01:03:19,200
Speaker 1: and all that stuff. The same is not true for

1187
01:03:19,440 --> 01:03:22,800
Speaker 1: smell because it's much more complex. It's not just a

1188
01:03:22,840 --> 01:03:26,360
Speaker 1: single frequency spectrum along which every smell sits. It's a

1189
01:03:26,480 --> 01:03:32,120
Speaker 1: super high dimensional space. Essentially, smell is detecting individual molecules

1190
01:03:32,120 --> 01:03:35,720
Speaker 1: of different kinds. You know, you're smelling a poop molecule,

1191
01:03:35,760 --> 01:03:39,280
Speaker 1: you're smelling a chicken molecule, you're smelling molecules from flowers. Really,

1192
01:03:39,320 --> 01:03:43,640
Speaker 1: smell is detecting super dilute presence of specific molecules in

1193
01:03:43,680 --> 01:03:45,800
Speaker 1: the air. It's really incredible that it works at all.

1194
01:03:46,080 --> 01:03:49,040
Speaker 2: This is one of the things that like, it's so

1195
01:03:49,160 --> 01:03:51,840
Speaker 2: hard for me to understand, and I think it's also

1196
01:03:52,000 --> 01:03:56,360
Speaker 2: just hard for experts to understand how smell works, because

1197
01:03:56,680 --> 01:03:58,160
Speaker 2: it is one of these things where it's like we

1198
01:03:58,240 --> 01:04:04,160
Speaker 2: have just a bunch of receptors and they kind there's

1199
01:04:04,200 --> 01:04:06,600
Speaker 2: some sort of lock and key mechanism that happens with

1200
01:04:07,120 --> 01:04:10,440
Speaker 2: these molecules and it sends a signal to the brain

1201
01:04:11,120 --> 01:04:15,800
Speaker 2: and then we experience that smell and it can be

1202
01:04:15,960 --> 01:04:19,920
Speaker 2: way more complicated, even in say like a dog, who

1203
01:04:20,000 --> 01:04:24,560
Speaker 2: is able to distinguish massive amount of smells. In fact,

1204
01:04:24,640 --> 01:04:27,520
Speaker 2: I would say like a dog's world is probably more

1205
01:04:27,600 --> 01:04:30,919
Speaker 2: smell focused than it is vision focused. Of course they

1206
01:04:31,160 --> 01:04:35,040
Speaker 2: can see, but smell is probably their primary way they

1207
01:04:35,120 --> 01:04:38,240
Speaker 2: experience the world, which is very different from humans.

1208
01:04:38,280 --> 01:04:40,720
Speaker 1: Yeah, dogs can be blind and they're like whatever, no

1209
01:04:40,800 --> 01:04:42,840
Speaker 1: big deal. As long as I can still smell, I

1210
01:04:42,840 --> 01:04:44,640
Speaker 1: can tell who's there and what they're doing, what they

1211
01:04:44,760 --> 01:04:47,680
Speaker 1: ate for dinner, like three weeks ago is incredible. And

1212
01:04:47,760 --> 01:04:50,600
Speaker 1: it all comes down to these super powerful lock and

1213
01:04:50,680 --> 01:04:54,000
Speaker 1: key mechanisms. Basically to detect which molecules are out there,

1214
01:04:54,360 --> 01:04:56,560
Speaker 1: what you need is some way to say, like, okay,

1215
01:04:56,640 --> 01:04:58,840
Speaker 1: here's a little chicken molecule, or here's a little molecule

1216
01:04:58,840 --> 01:05:01,000
Speaker 1: of pasta or whatever. I always want to understand these

1217
01:05:01,000 --> 01:05:03,320
Speaker 1: things from the microphysics point of view, like zoom in

1218
01:05:03,720 --> 01:05:06,240
Speaker 1: what is really happening? How do you have a sensor

1219
01:05:06,280 --> 01:05:08,680
Speaker 1: which reacts to only one kind of molecule and not

1220
01:05:08,720 --> 01:05:11,320
Speaker 1: another kind of molecule. So I talked to my wife

1221
01:05:11,320 --> 01:05:13,280
Speaker 1: about this, who's a biochemist. She has a pretty deep

1222
01:05:13,360 --> 01:05:16,120
Speaker 1: understanding of the fundamental mechanism. And essentially, you have these

1223
01:05:16,160 --> 01:05:18,520
Speaker 1: cells in your nose that have membranes in them, like

1224
01:05:18,560 --> 01:05:21,280
Speaker 1: every cell does, but you have these proteins which go

1225
01:05:21,440 --> 01:05:24,360
Speaker 1: across the membrane. They have some bits that stick out

1226
01:05:24,400 --> 01:05:26,320
Speaker 1: on the outside of the cell, and some bits on

1227
01:05:26,360 --> 01:05:28,480
Speaker 1: the stick on the inside of the cell, and the

1228
01:05:28,520 --> 01:05:31,440
Speaker 1: bits that stick on the outside all have funny, weird shapes,

1229
01:05:31,640 --> 01:05:34,640
Speaker 1: so they're basically like the lock that the molecule fits

1230
01:05:34,680 --> 01:05:37,080
Speaker 1: into like a key, so they trigger it. So if

1231
01:05:37,080 --> 01:05:39,840
Speaker 1: the right molecule comes along and fits into these little

1232
01:05:39,880 --> 01:05:42,080
Speaker 1: bits of the protein that stick out past the edge

1233
01:05:42,080 --> 01:05:44,120
Speaker 1: of the cell and interacts with it, it can then

1234
01:05:44,160 --> 01:05:47,600
Speaker 1: transmit a signal through the cell membrane into the inside

1235
01:05:47,640 --> 01:05:50,200
Speaker 1: of the cell and make something happen, and that's how

1236
01:05:50,240 --> 01:05:51,880
Speaker 1: you detect it. And then of course you have like

1237
01:05:52,040 --> 01:05:56,000
Speaker 1: hundreds or thousands or maybe even more kinds of receptors

1238
01:05:56,040 --> 01:05:59,240
Speaker 1: in your nose, so you can smell different kinds of stuff,

1239
01:06:00,120 --> 01:06:02,040
Speaker 1: just like a spectrum from red light to green light

1240
01:06:02,040 --> 01:06:05,080
Speaker 1: to blue light. It's like a huge list of individual

1241
01:06:05,160 --> 01:06:08,480
Speaker 1: different kinds of receptors that can all detect different kinds

1242
01:06:08,480 --> 01:06:09,200
Speaker 1: of molecules.

1243
01:06:09,480 --> 01:06:11,120
Speaker 2: I mean, it actually kind of reminds me of how

1244
01:06:11,120 --> 01:06:13,680
Speaker 2: the immune system works. It's a very similar lock and

1245
01:06:13,760 --> 01:06:18,080
Speaker 2: key mechanism, where you have immune cells and they have

1246
01:06:18,160 --> 01:06:21,600
Speaker 2: all sorts of surface receptors and they will be able

1247
01:06:21,680 --> 01:06:25,840
Speaker 2: to fit with like different kinds of antigens. Like that's

1248
01:06:26,000 --> 01:06:28,280
Speaker 2: like the key, and then the surface cell is like

1249
01:06:28,400 --> 01:06:30,919
Speaker 2: the lock, and then they fit together. And then once

1250
01:06:30,960 --> 01:06:35,200
Speaker 2: that happens, you have a basically chemical chain reaction that

1251
01:06:35,320 --> 01:06:38,240
Speaker 2: happens across the membrane and into the cell. So like

1252
01:06:38,280 --> 01:06:42,440
Speaker 2: that lock and key mechanism is so important in biology,

1253
01:06:42,480 --> 01:06:45,840
Speaker 2: and it's found sort of in all sorts of biological processes,

1254
01:06:45,960 --> 01:06:49,520
Speaker 2: including our sense of smell. Like those poop molecules are

1255
01:06:49,640 --> 01:06:51,760
Speaker 2: getting real intimate with your cells.

1256
01:06:51,800 --> 01:06:55,000
Speaker 1: They're unlocking something deep inside you. But it's even more

1257
01:06:55,000 --> 01:06:56,960
Speaker 1: complicated than just a lock and a key, which gives

1258
01:06:56,960 --> 01:06:58,760
Speaker 1: you the sense of like a mechanical thing. You might

1259
01:06:58,760 --> 01:07:01,240
Speaker 1: be wondering, like, well, who's turn earning the lock? Right,

1260
01:07:01,400 --> 01:07:03,800
Speaker 1: It's more complicated than just having the piece fit into

1261
01:07:03,800 --> 01:07:06,800
Speaker 1: the right slot. There are electric fields there, right, because

1262
01:07:06,840 --> 01:07:10,120
Speaker 1: these atoms have electrons whizzing around. That all has to

1263
01:07:10,160 --> 01:07:12,600
Speaker 1: fit in just perfectly so that the atoms like to

1264
01:07:12,640 --> 01:07:14,160
Speaker 1: hang out with each other. And then you have to

1265
01:07:14,200 --> 01:07:17,400
Speaker 1: have like the right hydrophobic properties. Maybe together the lock

1266
01:07:17,400 --> 01:07:19,680
Speaker 1: and the key element like to dispel water, They like

1267
01:07:19,760 --> 01:07:22,200
Speaker 1: to push water out, so they fit together really snugly.

1268
01:07:22,280 --> 01:07:24,520
Speaker 1: And these bits of these things which are squishy and

1269
01:07:24,640 --> 01:07:26,880
Speaker 1: have to have like the right squishiness to click together

1270
01:07:26,960 --> 01:07:29,000
Speaker 1: in the right way. And the end, what you're doing

1271
01:07:29,080 --> 01:07:33,280
Speaker 1: is transmitting some energy from the molecule into the receptor,

1272
01:07:33,440 --> 01:07:35,400
Speaker 1: and that either happens by coming in and hitting it

1273
01:07:35,520 --> 01:07:37,680
Speaker 1: or interacting it with it in some way. But it's

1274
01:07:37,760 --> 01:07:39,840
Speaker 1: not a deep bond. It's not like the lock and

1275
01:07:39,840 --> 01:07:43,560
Speaker 1: the key are forming some new macromolecule through covalent bonding.

1276
01:07:43,720 --> 01:07:46,280
Speaker 1: It's more like they're pushing up against each other. But

1277
01:07:46,360 --> 01:07:48,760
Speaker 1: as you say, Katy, it's not something we actually understand

1278
01:07:48,880 --> 01:07:51,120
Speaker 1: very well. There are all sorts of theories about how

1279
01:07:51,120 --> 01:07:54,400
Speaker 1: that energy gets transmitted. There's lock and key mechanism, where

1280
01:07:54,520 --> 01:07:56,680
Speaker 1: sort of mechanical transmission of energy is one of them.

1281
01:07:56,720 --> 01:07:59,800
Speaker 1: But there's another theory called vibration theory that the molecule

1282
01:07:59,800 --> 01:08:03,240
Speaker 1: that comes along is actually emitting a low energy photon

1283
01:08:03,520 --> 01:08:06,600
Speaker 1: like an infrared photon as it transitions from one state

1284
01:08:06,640 --> 01:08:09,520
Speaker 1: to another, and then that triggers the change of state

1285
01:08:09,680 --> 01:08:12,360
Speaker 1: by the receptor, which is moving from one state to

1286
01:08:12,400 --> 01:08:16,360
Speaker 1: another by absorbing this photon and doing it through quantum tunneling.

1287
01:08:16,840 --> 01:08:19,080
Speaker 1: There's two states. It couldn't otherwise get from one to

1288
01:08:19,120 --> 01:08:21,519
Speaker 1: the other. It needs a little bit of boost of energy,

1289
01:08:21,600 --> 01:08:24,080
Speaker 1: but doesn't actually have enough energy to go over the hump,

1290
01:08:24,240 --> 01:08:26,880
Speaker 1: so it tunnels through that barrier. We have, of course,

1291
01:08:26,920 --> 01:08:30,040
Speaker 1: have a whole podcast episode on quantum tunneling. But fundamentally

1292
01:08:30,120 --> 01:08:34,000
Speaker 1: the physics involved in smell is not something that we understand,

1293
01:08:34,000 --> 01:08:36,920
Speaker 1: which is incredible that it's still an open mystery, right,

1294
01:08:37,000 --> 01:08:40,360
Speaker 1: such basic questions of the human experience still not understood

1295
01:08:40,400 --> 01:08:42,160
Speaker 1: in terms of the fundamental physics.

1296
01:08:42,360 --> 01:08:46,440
Speaker 2: Well right, because I mean fundamental physics are not fully understood,

1297
01:08:46,439 --> 01:08:51,919
Speaker 2: and fundamental physics are fundamental to understanding how it interacts

1298
01:08:51,960 --> 01:08:54,240
Speaker 2: with biologies. I mean, I think it's just a humbling

1299
01:08:54,280 --> 01:08:57,559
Speaker 2: thing to remember that, hey, biology, it is completely linked

1300
01:08:57,600 --> 01:09:02,480
Speaker 2: with particle physics, like have a full understanding of biology,

1301
01:09:02,560 --> 01:09:04,880
Speaker 2: like we would need to have a full understanding of

1302
01:09:05,200 --> 01:09:08,840
Speaker 2: particle physics, so you know, hurry up, you guys figure

1303
01:09:08,840 --> 01:09:09,120
Speaker 2: it out.

1304
01:09:09,360 --> 01:09:11,920
Speaker 1: And there's so many questions still open about how smell

1305
01:09:11,960 --> 01:09:14,320
Speaker 1: works and how these receptors work. My wife Katrina was

1306
01:09:14,320 --> 01:09:16,920
Speaker 1: telling me that they find these receptors not just in

1307
01:09:16,960 --> 01:09:18,760
Speaker 1: your nose and of course in the back of your mouth,

1308
01:09:18,960 --> 01:09:21,080
Speaker 1: but all over your body, like on the palms of

1309
01:09:21,120 --> 01:09:24,040
Speaker 1: your hands, inside your body, like in your guts. There

1310
01:09:24,040 --> 01:09:26,639
Speaker 1: are these same kinds of receptors, which is like, are

1311
01:09:26,680 --> 01:09:30,080
Speaker 1: we smelling our own poop inside our body? Are you

1312
01:09:30,080 --> 01:09:33,200
Speaker 1: can smell a flour with your palm when you're holding it.

1313
01:09:33,600 --> 01:09:36,880
Speaker 1: These reactions are happening, we just don't always sense them.

1314
01:09:36,920 --> 01:09:40,280
Speaker 1: They don't always get converted by our brain into the

1315
01:09:40,400 --> 01:09:41,560
Speaker 1: smell sensation.

1316
01:09:42,000 --> 01:09:44,800
Speaker 2: Yeah, the gut thing is really interesting because there's definitely

1317
01:09:44,840 --> 01:09:47,320
Speaker 2: a lot of information that's sent from your gut to

1318
01:09:47,400 --> 01:09:50,479
Speaker 2: your brain and back and forth, and a lot of nerves,

1319
01:09:50,479 --> 01:09:53,160
Speaker 2: a lot of neural activity that actually happens in your gut.

1320
01:09:53,400 --> 01:09:57,320
Speaker 2: That's why things like ibs or like if you're anxious,

1321
01:09:57,920 --> 01:10:01,479
Speaker 2: that can impact your guts functioning and vice versa. But yeah,

1322
01:10:01,479 --> 01:10:03,439
Speaker 2: it's I mean, I don't think we know exactly what

1323
01:10:04,040 --> 01:10:09,320
Speaker 2: those essentially like smell and taste receptors inside your gut does,

1324
01:10:09,439 --> 01:10:11,720
Speaker 2: but it may have something to do with like how

1325
01:10:11,720 --> 01:10:14,880
Speaker 2: our bodies regulate our guts, like how much blood are

1326
01:10:14,880 --> 01:10:18,479
Speaker 2: we sending down to help speed up metabolism things like that.

1327
01:10:18,680 --> 01:10:21,400
Speaker 1: Yeah, it's sort of like a subconscious smelling, like it's

1328
01:10:21,400 --> 01:10:24,439
Speaker 1: a sensation of the presence of these molecules in a

1329
01:10:24,439 --> 01:10:27,160
Speaker 1: way you're not consciously experiencing.

1330
01:10:26,680 --> 01:10:28,439
Speaker 2: And thank goodness for that.

1331
01:10:29,720 --> 01:10:32,400
Speaker 1: And also a lot of these receptors trigger molecules we

1332
01:10:32,400 --> 01:10:34,840
Speaker 1: don't know, but we don't understand. It's not easy to

1333
01:10:34,840 --> 01:10:36,759
Speaker 1: look at a receptor and say, oh, this one obviously

1334
01:10:36,840 --> 01:10:39,160
Speaker 1: senses ketchup and this one's sense is mustard. And there's

1335
01:10:39,160 --> 01:10:41,559
Speaker 1: lots of receptors we like, well what is this one sense?

1336
01:10:41,680 --> 01:10:44,840
Speaker 1: We don't know, and they're all over the place, so

1337
01:10:44,880 --> 01:10:46,960
Speaker 1: we have a lot to learn. And then there's a

1338
01:10:47,000 --> 01:10:50,240
Speaker 1: lot of fascinating wrinkles on like how you actually experience

1339
01:10:50,400 --> 01:10:53,719
Speaker 1: that smell. And one of my favorite tidbits comes from rats.

1340
01:10:53,760 --> 01:10:55,840
Speaker 1: It turns out that in rodents is a very close

1341
01:10:55,880 --> 01:11:00,240
Speaker 1: connection between smell and sound, which means that like if

1342
01:11:00,240 --> 01:11:03,639
Speaker 1: they smell something, they smell it differently. If certain sounds

1343
01:11:03,720 --> 01:11:06,519
Speaker 1: are playing. So in rodent science, they call this neural

1344
01:11:06,600 --> 01:11:10,800
Speaker 1: convergence a new kind of perception called smound, which is

1345
01:11:10,800 --> 01:11:13,360
Speaker 1: a combination of smell and sound.

1346
01:11:13,640 --> 01:11:16,760
Speaker 2: Right, that is so interesting. I mean I think that

1347
01:11:17,439 --> 01:11:22,959
Speaker 2: very rarely can happen in humans if you are affected

1348
01:11:22,960 --> 01:11:27,120
Speaker 2: by something called synesthesia, which is when you're getting all

1349
01:11:27,160 --> 01:11:30,880
Speaker 2: your sensory information as one typically would, but then in

1350
01:11:30,920 --> 01:11:34,840
Speaker 2: your brain it is actually kind of mixing and matching

1351
01:11:35,160 --> 01:11:39,080
Speaker 2: your sensory experience. So like you'll smell something and you

1352
01:11:39,320 --> 01:11:43,160
Speaker 2: feel like that smell is a color, or you feel

1353
01:11:43,200 --> 01:11:47,400
Speaker 2: like a number is a certain kind of color or feeling,

1354
01:11:47,439 --> 01:11:50,720
Speaker 2: and it's very interesting. So like, I feel like this

1355
01:11:50,840 --> 01:11:53,960
Speaker 2: is one of the things, like it's usually difficult to know,

1356
01:11:54,240 --> 01:11:56,880
Speaker 2: like as humans, what it would be like to be

1357
01:11:56,920 --> 01:11:59,800
Speaker 2: an animal. But I bet if you ask someone with

1358
01:12:00,080 --> 01:12:03,360
Speaker 2: an esthesia, they could maybe give you something of an

1359
01:12:03,400 --> 01:12:06,200
Speaker 2: idea of this experience of the rats where they have

1360
01:12:06,920 --> 01:12:08,040
Speaker 2: this mound.

1361
01:12:08,560 --> 01:12:11,360
Speaker 1: Makes me wonder, like what music pairings we should be

1362
01:12:11,360 --> 01:12:14,519
Speaker 1: playing in fine restaurants, you know, because maybe your food

1363
01:12:14,960 --> 01:12:18,719
Speaker 1: smounds good with Mozart, but doesn't smeund good with Black

1364
01:12:18,760 --> 01:12:19,719
Speaker 1: Sabbath or whatever.

1365
01:12:20,000 --> 01:12:23,920
Speaker 2: I feel like Mozart would be good with like a kianti,

1366
01:12:24,040 --> 01:12:26,960
Speaker 2: whereas black Sabbath would be good with I don't know,

1367
01:12:27,479 --> 01:12:28,880
Speaker 2: red bull.

1368
01:12:28,920 --> 01:12:32,080
Speaker 1: There you go. Well, there's all sorts of fascinating biology

1369
01:12:32,120 --> 01:12:34,479
Speaker 1: and wrinkles. The experience of smell we don't have time

1370
01:12:34,520 --> 01:12:37,320
Speaker 1: to get into. You know, how dogs have like hundreds

1371
01:12:37,360 --> 01:12:40,200
Speaker 1: or tens of thousands of times more acute senses. The

1372
01:12:40,320 --> 01:12:44,160
Speaker 1: grizzly bears have even stronger senses than the bloodhound. How

1373
01:12:44,240 --> 01:12:48,280
Speaker 1: people can sometimes smell like whether they're related to somebody

1374
01:12:48,680 --> 01:12:52,840
Speaker 1: based on their body odor. It's really incredible, it really is.

1375
01:12:53,120 --> 01:12:55,080
Speaker 2: The Only thing I'll say is that if you want

1376
01:12:55,080 --> 01:12:57,840
Speaker 2: to make your dog happy, let them smell stuff like

1377
01:12:57,920 --> 01:13:00,599
Speaker 2: that is, if you let your dogs smell, smell all

1378
01:13:00,600 --> 01:13:03,200
Speaker 2: the smells, they'll be so happy. It's like them going

1379
01:13:03,200 --> 01:13:05,760
Speaker 2: to the movies or to a museum. Smells are a

1380
01:13:05,800 --> 01:13:07,080
Speaker 2: dog's whole world.

1381
01:13:07,200 --> 01:13:09,479
Speaker 1: And in the end, all of this smell, in terms

1382
01:13:09,479 --> 01:13:11,640
Speaker 1: of the fundamental physics, is chemistry.

1383
01:13:11,760 --> 01:13:11,880
Speaker 3: Right.

1384
01:13:11,920 --> 01:13:17,240
Speaker 1: We're talking about the interactions of molecules with each other, mechanical, electrostatic,

1385
01:13:17,479 --> 01:13:22,040
Speaker 1: but fundamentally it's all chemistry. It's all electromagnetic. Everything involved

1386
01:13:22,080 --> 01:13:26,280
Speaker 1: in smell is electromagnetic interactions of big complex molecules with

1387
01:13:26,360 --> 01:13:29,800
Speaker 1: other complex molecules, whether that's mechanical which again is built

1388
01:13:29,840 --> 01:13:34,920
Speaker 1: on the electromagnetic force, or literal electrostatic interactions between these molecules.

1389
01:13:35,160 --> 01:13:36,880
Speaker 1: It's all electromagnetism.

1390
01:13:37,280 --> 01:13:41,440
Speaker 2: So let me guess is touch also electromagnetism.

1391
01:13:42,479 --> 01:13:46,040
Speaker 1: Touch also seems to be electromagnetism. The way you sense

1392
01:13:46,160 --> 01:13:49,240
Speaker 1: touch is through various kinds of sensors in your skin.

1393
01:13:49,640 --> 01:13:54,120
Speaker 1: Some sense pressure, some sense temperature, some sense damage. Right,

1394
01:13:54,439 --> 01:13:57,640
Speaker 1: each one has a special kind of mechano receptor to

1395
01:13:57,720 --> 01:13:59,920
Speaker 1: tell like are you being squeezed or are you being

1396
01:14:00,120 --> 01:14:02,840
Speaker 1: heat it up? And then they send their signals up

1397
01:14:02,880 --> 01:14:06,719
Speaker 1: to your brain using of course electromagnetic pulses.

1398
01:14:07,120 --> 01:14:09,840
Speaker 2: That is so interesting. So like when I'm zamped with

1399
01:14:09,880 --> 01:14:15,680
Speaker 2: some static electricity, I'm having electromagnetism zap me, but then

1400
01:14:15,720 --> 01:14:21,880
Speaker 2: also electromagnetism telling my brain ouch I got zapped exactly.

1401
01:14:22,040 --> 01:14:24,839
Speaker 1: And then the last sense, taste is very closely connected

1402
01:14:24,880 --> 01:14:28,000
Speaker 1: to the sense of smell, as we talked about. Of course,

1403
01:14:28,280 --> 01:14:30,400
Speaker 1: of course your mouth is different from your nose, and

1404
01:14:30,439 --> 01:14:32,880
Speaker 1: you have a tongue with taste receptors on it, but

1405
01:14:32,960 --> 01:14:36,719
Speaker 1: taste receptors are not nearly as complicated or as varied

1406
01:14:36,760 --> 01:14:39,240
Speaker 1: as smell receptors. You have a few thousand of them

1407
01:14:39,240 --> 01:14:42,720
Speaker 1: on your tongue, which can sense basic things about classes

1408
01:14:42,760 --> 01:14:47,280
Speaker 1: of molecules, so you have like sweet, sweet, sour, salt, bitter, savory,

1409
01:14:47,400 --> 01:14:50,160
Speaker 1: or sometimes people call it umami. Each of these are

1410
01:14:50,520 --> 01:14:53,320
Speaker 1: like receptors in your nose, except they're more coarse. They

1411
01:14:53,439 --> 01:14:56,880
Speaker 1: like detect certain classes of molecules that they can trigger.

1412
01:14:56,920 --> 01:14:59,439
Speaker 1: They're not like one of a kind molecule receptors the

1413
01:14:59,439 --> 01:15:02,439
Speaker 1: way your nose, which is why most of your sense

1414
01:15:02,479 --> 01:15:05,880
Speaker 1: of taste actually comes from your nose. Your mouth contributes

1415
01:15:05,920 --> 01:15:07,960
Speaker 1: to it, and your tongue helps. But if you last

1416
01:15:07,960 --> 01:15:09,840
Speaker 1: time you've had a cold, for example, and you couldn't

1417
01:15:09,880 --> 01:15:13,320
Speaker 1: smell anything, you might notice that things sort of taste cardboardy.

1418
01:15:13,439 --> 01:15:16,040
Speaker 1: And that's because the tongue can only distinguish like five

1419
01:15:16,160 --> 01:15:19,559
Speaker 1: different senses, and your nose can distinguish like hundreds and

1420
01:15:19,760 --> 01:15:22,440
Speaker 1: hundreds of different senses. It's much more complex.

1421
01:15:23,240 --> 01:15:25,639
Speaker 2: That's why you hold your nose when you're taking cough

1422
01:15:25,680 --> 01:15:27,840
Speaker 2: medicine and makes it taste less bad.

1423
01:15:28,880 --> 01:15:30,960
Speaker 1: And I thought this was fascinating. It turns out that

1424
01:15:31,080 --> 01:15:35,160
Speaker 1: most of smell's contribution to flavor occurs when you exhale,

1425
01:15:35,280 --> 01:15:37,479
Speaker 1: as opposed to with smell. When you smell something, that's

1426
01:15:37,520 --> 01:15:40,840
Speaker 1: during inhalation, right, you're breathing it in across those receptors.

1427
01:15:40,920 --> 01:15:43,240
Speaker 1: But when you eat something, it's when you breathe out

1428
01:15:43,640 --> 01:15:46,880
Speaker 1: that smell contributes to that sense of taste. It's really

1429
01:15:47,200 --> 01:15:49,160
Speaker 1: sort of incredible how closely linked they are.

1430
01:15:49,479 --> 01:15:51,559
Speaker 2: I'm sorry to keep bringing it back to dogs, but

1431
01:15:51,720 --> 01:15:55,240
Speaker 2: it reminds me of how like with thugs, when they exhale,

1432
01:15:55,360 --> 01:15:59,040
Speaker 2: they're getting a ton more information from the smell, like

1433
01:15:59,120 --> 01:16:02,679
Speaker 2: in their nose, like a specific channels in their nose

1434
01:16:02,760 --> 01:16:05,800
Speaker 2: that allows them to experience more, which you know, you

1435
01:16:05,840 --> 01:16:08,400
Speaker 2: always think that like when you're breathing in, you're breathing

1436
01:16:08,400 --> 01:16:11,520
Speaker 2: in a smell like that's where you're getting the biggest experience.

1437
01:16:11,600 --> 01:16:15,200
Speaker 2: But exhaling can give us, maybe not in terms of

1438
01:16:15,280 --> 01:16:18,160
Speaker 2: identifying smells like with dogs, but for us it gives

1439
01:16:18,200 --> 01:16:21,640
Speaker 2: us this much grander experience with flavor m M.

1440
01:16:22,840 --> 01:16:25,240
Speaker 1: And in the end, in terms of the fundamental physics,

1441
01:16:25,280 --> 01:16:28,720
Speaker 1: all this again is chemistry. It's the interactions of molecules,

1442
01:16:28,720 --> 01:16:31,479
Speaker 1: which is determined by their structure, which is based on

1443
01:16:31,520 --> 01:16:35,799
Speaker 1: their atomic bonds, which is electromagnetism and their electrostatic propulsion

1444
01:16:35,880 --> 01:16:38,400
Speaker 1: of each other. So in the end, this sense is

1445
01:16:38,439 --> 01:16:40,120
Speaker 1: also electromagnetism.

1446
01:16:40,520 --> 01:16:45,120
Speaker 2: So has everything we've talked about been electromagnetism except for

1447
01:16:45,280 --> 01:16:49,320
Speaker 2: that inner ear sort of accelerometer.

1448
01:16:49,680 --> 01:16:52,600
Speaker 1: Yes, it turns out that electromagnetism is really the fundamental

1449
01:16:52,600 --> 01:16:55,719
Speaker 1: force we use to experience the universe, with the exception

1450
01:16:55,880 --> 01:16:59,520
Speaker 1: of this sense of balance, which also is connected to electromagnetism.

1451
01:16:59,560 --> 01:17:02,200
Speaker 1: Of course, because it's built out of these pieces that

1452
01:17:02,320 --> 01:17:07,160
Speaker 1: use electromagnetic structures. Everything really is fundamentally due to electromagnetism.

1453
01:17:07,360 --> 01:17:09,839
Speaker 1: We don't rely on the weak force or the strong

1454
01:17:09,920 --> 01:17:13,479
Speaker 1: force in order to interact with the universe. Though of

1455
01:17:13,520 --> 01:17:16,840
Speaker 1: course without the strong force you couldn't have these molecules,

1456
01:17:17,120 --> 01:17:19,880
Speaker 1: and so you might argue that the core structure of

1457
01:17:19,880 --> 01:17:22,840
Speaker 1: the atom is due to the strong force, but doesn't

1458
01:17:22,840 --> 01:17:25,320
Speaker 1: really play a deep role in how those things interact.

1459
01:17:25,320 --> 01:17:28,920
Speaker 1: That's really due to the electromagnetic interactions of the atoms,

1460
01:17:28,920 --> 01:17:33,160
Speaker 1: how they bond together. So yeah, underlying everything is electromagnetism.

1461
01:17:33,360 --> 01:17:36,280
Speaker 2: It's kind of a particle chicken before the particle egg

1462
01:17:36,479 --> 01:17:38,600
Speaker 2: kind of question one for philosophers.

1463
01:17:38,880 --> 01:17:42,040
Speaker 1: Yeah, although there's another side of the story, which is

1464
01:17:42,040 --> 01:17:44,920
Speaker 1: that maybe all these forces are more closely connected than

1465
01:17:44,920 --> 01:17:47,880
Speaker 1: we initially described. I told you about how electricity and

1466
01:17:47,920 --> 01:17:50,719
Speaker 1: magnetism are really just two sides of the same coin.

1467
01:17:51,120 --> 01:17:53,599
Speaker 1: About fifty years ago we discovered that the weak force

1468
01:17:53,720 --> 01:17:56,280
Speaker 1: is actually linked to electricity and magnetism in a very

1469
01:17:56,280 --> 01:17:59,920
Speaker 1: similar way. You put them together into something we call electroweak,

1470
01:18:00,280 --> 01:18:03,360
Speaker 1: which is actually a much prettier and much more sensible object,

1471
01:18:03,439 --> 01:18:06,760
Speaker 1: has more symmetries, it's linked together. It's really this coin

1472
01:18:06,840 --> 01:18:08,519
Speaker 1: has three sides. It turns out.

1473
01:18:08,600 --> 01:18:11,080
Speaker 2: Wow, you just blew my mind. I can't picture a

1474
01:18:11,120 --> 01:18:14,000
Speaker 2: coin with three sides. I guess it technical. Wait, a

1475
01:18:14,040 --> 01:18:16,320
Speaker 2: coin does have three sides, because you got the head,

1476
01:18:16,360 --> 01:18:17,960
Speaker 2: you got the tails, and then you got the little

1477
01:18:18,000 --> 01:18:18,840
Speaker 2: rim around it.

1478
01:18:19,040 --> 01:18:21,280
Speaker 1: The weak force is the rim around the coin of

1479
01:18:21,320 --> 01:18:24,160
Speaker 1: electricity and magnetism. So in the end, the weak force

1480
01:18:24,240 --> 01:18:27,000
Speaker 1: is also playing a role in your sensus because it's

1481
01:18:27,120 --> 01:18:30,640
Speaker 1: part of the electra weak force, which really fundamentally is

1482
01:18:30,640 --> 01:18:33,080
Speaker 1: the thing that lets you interact with the universe. Lots

1483
01:18:33,120 --> 01:18:35,720
Speaker 1: of people are working on grand unified theories which would

1484
01:18:35,720 --> 01:18:39,280
Speaker 1: combine the strong force with the electroweek into one single

1485
01:18:39,439 --> 01:18:43,320
Speaker 1: unified force to describe all of these quantum interactions. And

1486
01:18:43,400 --> 01:18:45,840
Speaker 1: so if that is successful, maybe one day we will

1487
01:18:45,880 --> 01:18:48,200
Speaker 1: say that there's just one force out there that lets

1488
01:18:48,280 --> 01:18:49,719
Speaker 1: us experience the universe.

1489
01:18:50,080 --> 01:18:52,880
Speaker 2: Daniel, you told me Star Wars was lying to me

1490
01:18:53,000 --> 01:18:53,799
Speaker 2: about the force.

1491
01:18:56,720 --> 01:19:00,599
Speaker 1: In the end, it's all midichlorians. Those are the fundamental

1492
01:19:00,600 --> 01:19:01,960
Speaker 1: little gremlins of the universe.

1493
01:19:02,200 --> 01:19:05,880
Speaker 2: And we've done it. We've jumped the shark.

1494
01:19:06,120 --> 01:19:08,200
Speaker 1: So an important way that we see the universe is

1495
01:19:08,280 --> 01:19:11,840
Speaker 1: literally by seeing photons. But it turns out that electromagnetism

1496
01:19:12,080 --> 01:19:15,080
Speaker 1: is deeply rooted in every kind of sense we have

1497
01:19:15,200 --> 01:19:17,559
Speaker 1: of the universe, which gives us a rich and very

1498
01:19:17,600 --> 01:19:20,000
Speaker 1: picture of what's out there, but also limits us in

1499
01:19:20,040 --> 01:19:22,120
Speaker 1: what we can do and what we can experience. There's

1500
01:19:22,120 --> 01:19:23,960
Speaker 1: lots of stuff out there in the universe that doesn't

1501
01:19:24,000 --> 01:19:28,759
Speaker 1: experience electromagnetism, like dark matter, and so our electromagnetic based

1502
01:19:28,840 --> 01:19:31,200
Speaker 1: senses might be missing out on the bigger picture.

1503
01:19:31,400 --> 01:19:35,599
Speaker 2: Electromagnetism made me new friends and made me prettier too,

1504
01:19:36,680 --> 01:19:40,400
Speaker 2: So get your electromagnetism today, call now.

1505
01:19:42,040 --> 01:19:45,439
Speaker 1: This podcast is sponsored by Big Electron. Thanks everybody for

1506
01:19:45,479 --> 01:19:56,160
Speaker 1: listening and tune in next time. Thanks for listening, and

1507
01:19:56,200 --> 01:19:58,920
Speaker 1: remember that Daniel and Jorge explain the Universe is a

1508
01:19:58,960 --> 01:20:03,080
Speaker 1: production of I heart Radio. Or more podcasts from iHeartRadio,

1509
01:20:03,200 --> 01:20:07,360
Speaker 1: visit the iHeartRadio app, Apple Podcasts, or wherever you listen

1510
01:20:07,439 --> 01:20:08,599
Speaker 1: to your favorite shows.