Speaker 1: If you get up early to walk the dog, you
Speaker 1: might wonder why all the morning.
Speaker 2: Fog does blood rush to the head of upside down bats?
Speaker 2: Or do adaptations help deal with all of that?
Speaker 1: A spinning black hole is quite the disgrace. It breaks
Speaker 1: causality all over the place.
Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's
Speaker 2: answers will help make it right.
Speaker 1: Welcome to listener questions number thirty four on Daniel and
Speaker 1: Kelly's Extraordinary Universe.
Speaker 2: Hello, I'm Kelly Waiter Smith. I study parasites and space,
Speaker 2: and I'm excited that today we've got nature, We've got
Speaker 2: we've got black holes, We've got all the good stuff
Speaker 2: on the show today.
Speaker 3: Hi.
Speaker 1: I'm Daniel. I'm a particle physicist, and I almost certainly
Speaker 1: don't have a goat giving birth in my backyard.
Speaker 2: Yeah, that's right. Daniel today was like, Hey, Kelly, do
Speaker 2: you want to record an hour early? And I was like, well,
Speaker 2: first I have to see if my goat needs to
Speaker 2: have a bowel movement or if she's about to give
Speaker 2: birth early. We've all been there for moms. But but yeah,
Speaker 2: I and actually I think it was I think it
Speaker 2: could be both.
Speaker 1: Wow.
Speaker 2: So between every segment today, I'm going to run out
Speaker 2: and check on my goat and see how she's doing.
Speaker 1: That's right. You could all be witnesses to the miracle.
Speaker 2: Of life, that's right. Yeah, I know, or a goat
Speaker 2: pooping good Yeah, or both or both, probably both, because
Speaker 2: it's biology.
Speaker 1: I guess both count as the miracle of life.
Speaker 4: Right.
Speaker 1: They're both important functions, that's right.
Speaker 2: You know, when you don't poop, you kind of wish
Speaker 2: you were dead, I'm guessing. So, so you need both,
Speaker 2: you need both?
Speaker 1: All right. Well that's the backdrop. But in the foreground
Speaker 1: today we are addressing your curiosity. We are talking about
Speaker 1: questions you have about how the universe works, from six
Speaker 1: year old wondering about fog on the way to school
Speaker 1: all the way to the inner horizons of spinning black holes.
Speaker 2: And I got to tell you, as of today, I
Speaker 2: am changing my strategy a little bit, because my strategy
Speaker 2: has been I take questions from listeners that I do
Speaker 2: not know the answer to, that are hard that I
Speaker 2: can't figure out quickly, and I put them on my
Speaker 2: list and those are the ones that end up on
Speaker 2: the show. And now I only have questions that take
Speaker 2: me like ten hours or more to answer on my list.
Speaker 2: And so next time someone asked me a real softball question,
Speaker 2: I'm throwing that on my list for a listener question
Speaker 2: episode because I need some easy ones, sort of like
Speaker 2: sprinkled in there, because this one was a bit.
Speaker 1: Tough unsolved mysteries of biology. Yeah, I did that too,
Speaker 1: but I also mix in easier questions that I think
Speaker 1: a lot of people will be interested in answer, or
Speaker 1: that I think will be fun to joke about with you.
Speaker 2: Oh oh, those are all good strategies. Yeah, all right, Well,
Speaker 2: we learn from each other as much as we learn
Speaker 2: from the listeners, which is lovely. We're all learning from
Speaker 2: each other. What a great community.
Speaker 1: And today we're starting with a question from a six
Speaker 1: year old. This is a future scientist, folks, somebody who
Speaker 1: looks out in the world and wants to understand what's
Speaker 1: going on. So let's get started with our first question.
Speaker 5: Hey, Daniel Kelly, So our son just turns six and
Speaker 5: he's starting kindergarten this year.
Speaker 2: With that, we've been getting up earlier in the mornings
Speaker 2: and he started to notice something.
Speaker 6: By Jeja Yeho FuG and money.
Speaker 2: This is such a great question. I love this question.
Speaker 2: And also I'm particularly excited about fog since we moved
Speaker 2: out to a farm that has these big fields, because
Speaker 2: the fog will sometimes roll across the fields, and I
Speaker 2: am really into zombie movies, and every once in a
Speaker 2: while I'll look out and as the fog rolls across
Speaker 2: the field, I'm like the zombies. They must be coming,
Speaker 2: because it looks like the setting for a zombie movie.
Speaker 2: And then I'm a little disappointed because this Bomi's never
Speaker 2: come up out of the fog and I never get
Speaker 2: to use my taekwondo skills. But that's probably better i'd
Speaker 2: be dead. So all right, Daniel, where does the fog
Speaker 2: come from?
Speaker 1: It's foggy in the morning because fog forms when air
Speaker 1: gets colder, and so at night it gets colder because
Speaker 1: it's not as much sunshine, and so it gets foggy.
Speaker 1: That's the answer I'm aiming at a six year old.
Speaker 1: But then, of course we can dig in deeper into
Speaker 1: the science for the rest of the listeners. Does that
Speaker 1: make sense?
Speaker 2: I guess I don't know why it getting colder should
Speaker 2: make it foggy, And I bet the six year old
Speaker 2: is also saying, give me a better answer. Daniel. This
Speaker 2: is not why I listen to dKu.
Speaker 1: All right, fair point, let's dig in. So what is
Speaker 1: fog anyway? Fog is water. Water can be a solid ice,
Speaker 1: it can be a liquid that's what we usually call water,
Speaker 1: or it can be vapor. Okay, that vapor is invisible
Speaker 1: and he can mix with the air. Or we sometimes
Speaker 1: say the air is holding that water. You can't see
Speaker 1: that water when it's but you can tell that it's there,
Speaker 1: like when you go outside. The air can be humid,
Speaker 1: which feels sticky, or if you're lucky enough to live
Speaker 1: in California, the air can feel fairly dry, right, or
Speaker 1: like I visited Houston recently, where the air is like chewy.
Speaker 2: Yeah, yeah, I don't miss that about Houston. Really gotta
Speaker 2: be honest exactly.
Speaker 1: But if there's more water then the air can hold,
Speaker 1: then it condenses out and you get droplets, clouds, steam, fog,
Speaker 1: this kind of stuff. So the air is kind of
Speaker 1: like a sponge and that it can hold some water,
Speaker 1: but if you put too much into it, it's gonna
Speaker 1: leak out. And so when there's more water in the
Speaker 1: air that it can hold, then you get fog or
Speaker 1: then you get rain. And that's called the dew point.
Speaker 1: The dew point is the temperature where the air is
Speaker 1: fully saturated, the relative humidity is one hundred percent. It
Speaker 1: can't hold anymore. And if you go below the dew point,
Speaker 1: then you get dew where the water like precipitates out
Speaker 1: into little droplets and forms on plants and stuff.
Speaker 2: And that's what we call do okay, all right, So
Speaker 2: at night it gets colder, and the reason that matters
Speaker 2: is because cold air can hold less water, right.
Speaker 1: That's right. Warmer air can hold more water, and colder
Speaker 1: air can hold less water. So if you have a
Speaker 1: bunch of air and it's got some water in it
Speaker 1: and it's all fine, and it can handle that much
Speaker 1: water you're like seventy five percent humidity. Then as you
Speaker 1: cool that air down, it can't hold as much water.
Speaker 1: And at some point it passes the temperature where it's
Speaker 1: at one hundred percent humidity. It's the temperature at which
Speaker 1: it's holding all the water than it can. Then you
Speaker 1: pass that, you go even colder, and it can't hold
Speaker 1: that water anymore, so it comes out of the air
Speaker 1: and it makes fog. So fundamentally what's happening here is
Speaker 1: as you say, how much water the air can hold
Speaker 1: depends on the temperature, and you might wonder, like why
Speaker 1: is that? Is it related to, for example, how much
Speaker 1: like salt you can dissolve into water, which also depends
Speaker 1: on temperature, Like you put salt into water. You can
Speaker 1: dissolve more salt and water when it's hot than when
Speaker 1: it's cold.
Speaker 2: Right, Okay, So I guess what I'm wondering is, all right,
Speaker 2: so you're outside on a particular kind of day where
Speaker 2: there's a lot of moisture in the air and it's warm,
Speaker 2: and so like, what kind of warm day would result
Speaker 2: in the air holding as much water as possible? Like
Speaker 2: would a warm day always hold as much water as
Speaker 2: possible or does it need to have like rained recently
Speaker 2: and now there's more water in the air and so
Speaker 2: it's holding as much water as it can. Basically, my
Speaker 2: question is why isn't there fog every single morning? And
Speaker 2: so I'm trying to figure out the conditions that result
Speaker 2: in one hundred percent water being in the air.
Speaker 1: Yeah, cool question, So why does it happen sometimes and
Speaker 1: not other times? So in order for this to happen,
Speaker 1: you need moist air, you need water to be in
Speaker 1: the air, and that's why you often see fog like
Speaker 1: near valleys or near the ocean or near lakes, or
Speaker 1: after rainy days or in fall when the nights are
Speaker 1: really really long, so it gets colder at night than
Speaker 1: it does in the summer. So yeah, you need a
Speaker 1: source of that water. So if it's rained, or if
Speaker 1: you have a valley with a river or a lake
Speaker 1: or something, you need a source of that water in
Speaker 1: order to make it moist. So you ask, like, what
Speaker 1: kind of day is going to be like hot and
Speaker 1: moist something where it rained or where there's a nearby
Speaker 1: body of water to evaporate from. You need that source
Speaker 1: of water and you need to get it up into
Speaker 1: the air on that hot day, and then you need
Speaker 1: to cool it down. And the best way for that
Speaker 1: to happen is for the night to be clear so
Speaker 1: there's good cooling because otherwise some of that heat is
Speaker 1: going to be reflected by the clouds back at the earth.
Speaker 1: For there to be very light winds because winds tend
Speaker 1: to mix up the hot and the cold air, and
Speaker 1: for the ground to be as cold as possible. So
Speaker 1: on a clear night with light wind and cool ground
Speaker 1: after a rainy day or near a lake, you're very
Speaker 1: likely to get fog.
Speaker 2: Okay, awesome, Now let's give me why do I want
Speaker 2: to know about salt.
Speaker 1: Also, when I was reading about this, I was thinking
Speaker 1: about air being saturated by water and imagining that maybe
Speaker 1: it was similar to dissolving something into a solution. Like
Speaker 1: you know how you can put salt into water and
Speaker 1: then you don't see it right. It's not visible the
Speaker 1: same way that there can be like water in the air,
Speaker 1: but you're not looking at it right. It's like held
Speaker 1: by the air, And so I imagined that it was similar.
Speaker 1: Maybe this is the same kind of process. You can
Speaker 1: use your intuition. It turns out it's not. Yeah, when
Speaker 1: you dissolve salt into water, the salt actually forms bonds
Speaker 1: with the water. It's like actually a chemical solution. But
Speaker 1: water in the air is just more like a mixture
Speaker 1: of gases. You have like a mixture of air and
Speaker 1: water vapor. So it's not a great analogy. So for
Speaker 1: those people listening and thinking you can use your intuition
Speaker 1: for salt and water to understand air and water, that's
Speaker 1: a bit of a trap. So don't go down that hole.
Speaker 1: But there is something really fascinating happening here. Chemically, we
Speaker 1: talked about the dew point, the temperature beyond which things
Speaker 1: precipitate out into the air. It's not actually quite so simple.
Speaker 1: What's really happening is you have condon at every temperature,
Speaker 1: and you also have evaporation at every temperature. What happens
Speaker 1: when you cross the duw point is that you have
Speaker 1: more condensation than evaporation. So above the due point, you
Speaker 1: have more evaporation than condensation, so the air is taking
Speaker 1: in more water if you like, are injecting water somehow,
Speaker 1: then the air is gobbling that up, whereas below the
Speaker 1: due point you have more condensation than evaporation, so the
Speaker 1: air is losing the water. So it's a smooth transition
Speaker 1: as you cross the due point between being dominated by
Speaker 1: condensation and being dominated by evaporation. And this helps you
Speaker 1: understand why it's temperature dependent also because imagine the air
Speaker 1: and you have all these molecules of air, and then
Speaker 1: you also have water in the air, right, But there's
Speaker 1: no bonds between the water and the air, but there
Speaker 1: are bonds between the water molecules. So you have a
Speaker 1: droplet of water in the air like a little in
Speaker 1: one piece of fog, like a fog particle or a
Speaker 1: foggino or whatever. Then it's held together by little bonds
Speaker 1: because water is polar, remember, and so like one end
Speaker 1: of it is charged positive, one end of his charge negative,
Speaker 1: so it can kind of stick together. So water molecules
Speaker 1: when it's a little drop of fog are bound together
Speaker 1: by these hydrogen bonds between the molecules, and in order
Speaker 1: to evaporate, they have to have enough energy, enough kinetic
Speaker 1: energy to evaporate. So as the temperature goes up, more
Speaker 1: of these things have enough kinetic energy to break those
Speaker 1: bonds and evaporate into the air. So that's why at
Speaker 1: higher temperatures there's more water that can bounce around without
Speaker 1: getting stuck to other little water molecules and making little
Speaker 1: fuggy know, particles. So it's all about the temperature of
Speaker 1: the water really and force. The temperature of the air
Speaker 1: and the water are the same because they're an equilibrium.
Speaker 2: So what do you think it is about foggy mornings
Speaker 2: that make zombies more likely to be moving around? You
Speaker 2: look a little frustrated.
Speaker 1: Actually, sorry, I pride myself in being able to prepare
Speaker 1: for almost any question. You're going to ask, Wow, you
Speaker 1: totally caught me slash footed. So here's a completely impromptu answer.
Speaker 1: The Foggino particles interact with the zombie field, and so
Speaker 1: there's a resonance between those two, and so sometimes the
Speaker 1: zombie field will get energy from the Foggino particles and
Speaker 1: then you'll just precipitate zombies out of the quantum vacuum.
Speaker 2: Holy wow. Yeah, oh my gosh.
Speaker 1: Also that was complete nonsense and so.
Speaker 2: Obviously, but that was amazing. You used all the right
Speaker 2: words in all of the fancy ways, and you know,
Speaker 2: I think maybe we should start doing like a supernatural
Speaker 2: sort of podcast, and then maybe we could get ahead
Speaker 2: of Oh, what is the show that's ahead of us
Speaker 2: watch Chronicles. Yeah.
Speaker 1: No, that's just a lesson and how easy it is
Speaker 1: to sound like you know what you're talking about if
Speaker 1: you use big, fancy words, even if you're spewing gibberish.
Speaker 2: Yes, all right, anyway, okay, so sorry, back to the
Speaker 2: fogginos and okay, so so do in the morning fog
Speaker 2: that has settled on plants and stuff exactly. Side note,
Speaker 2: just to like Kelly being a nature nerd. One of
Speaker 2: my favorite things in the morning is to walk through
Speaker 2: our hayfields and see all of the teeny tiny little
Speaker 2: spiderwebs that I always miss, but you can see them
Speaker 2: because the dew has settled on them. There are literally
Speaker 2: thousands of them out there. There's this tiny little universe
Speaker 2: that you can only see in the morning when the
Speaker 2: dew makes it visible and you miss it otherwise. And
Speaker 2: it's just like when you look at the world at
Speaker 2: different scales, there's all of these things that you missed
Speaker 2: at the scale that you live. And anyway, I love
Speaker 2: walking in the morning, like when you can still see
Speaker 2: what the dew makes visible, and a good reason to
Speaker 2: get up early.
Speaker 1: Sometimes in high school I had to get up early
Speaker 1: for marching band, and the field was always covered in
Speaker 1: dew which is then frozen. Oh and crunching on those
Speaker 1: frozen blades of grass that was always so satisfied.
Speaker 2: Oh okay, I thought you were going to say you
Speaker 2: didn't like that, So yes, two positive stories about getting
Speaker 2: up early.
Speaker 1: I did not like getting up early for marching band.
Speaker 1: That was the one good thing about it. The first
Speaker 1: in grass, you know, it's satisfying. The way like stepping
Speaker 1: on a frozen river and cracking that ice is also satisfying.
Speaker 1: I don't know if you feel that way.
Speaker 2: Yeah, no, I like that. I like that. Can I
Speaker 2: share one negative getting up early story? And then we
Speaker 2: really need to get back? Should we just get back
Speaker 2: on track? Maybe we should just get back on track?
Speaker 1: Well, why don't you say it? And it's not funny enough?
Speaker 2: Okay?
Speaker 3: All right?
Speaker 2: So when I was in high school, senior year of
Speaker 2: high school, I worked at a bakery at a zoo,
Speaker 2: and I had to get there at five am to
Speaker 2: cook the cookies before everyone got there. And one morning
Speaker 2: I was feeling super grumpy and I was like, I
Speaker 2: can't who in high school gets a job where you
Speaker 2: have to be there at five am? What am I thinking?
Speaker 4: Right?
Speaker 2: And so I get there and this little bird lands
Speaker 2: on a fence and it starts singing this beautiful song,
Speaker 2: and I'm like, okay, all right, this is why you
Speaker 2: get here?
Speaker 1: And was there fog?
Speaker 2: I don't remember. I don't remember that.
Speaker 1: I just remember telling there has to be fogg to
Speaker 1: connect to the question, and.
Speaker 2: There was fog, but no zombies and anyway, singing this
Speaker 2: beautiful song, and then out of nowhere, a raptor comes
Speaker 2: by and literally oops the bird up and rips its
Speaker 2: neck out, and I was like, that's mornings for you. Yes,
Speaker 2: that feels a little bit more on key, and anyway,
Speaker 2: I felt so bad for that.
Speaker 1: That's biology for that.
Speaker 2: That's biology for you, and anyway that felt Yeah. I
Speaker 2: was like, no, right, okay, that's right. This is why
Speaker 2: you don't get up in the mornings early birds, I
Speaker 2: don't know they get their next ripped out.
Speaker 1: Be careful early birds because in the morning there's fog
Speaker 1: and the raptors can swoop down out of their hiding
Speaker 1: places in the mist. That's right, all right, So chance,
Speaker 1: send this explanation to your six year old and let's
Speaker 1: see if we've scratched that itch or confused them with
Speaker 1: stories of raptors and zombies.
Speaker 6: And kids so much. Nine questions. I think it's cool, Sponge.
Speaker 6: I don't have any questions, thank you.
Speaker 1: Okay, we're back and we're answering questions from listeners as
Speaker 1: well as giving live updates on Kelly's goat.
Speaker 2: Oh that's staying in the show.
Speaker 1: Huh Kelly, did your goat give birth?
Speaker 2: No? Not yet, not yet. She was chewing her cut
Speaker 2: and she got up to say hi. When I went
Speaker 2: out to check on her. So she is not in
Speaker 2: active labor right now, but her utters are bigger, so.
Speaker 1: I think we're are they utterly huge?
Speaker 2: They're not utterly huge yet, but her bag has expanded,
Speaker 2: as the vet said, So.
Speaker 1: Well, I'm gonna milk these jokes as as I can.
Speaker 2: Amazing, amazing, and I'm going to see how many zombie
Speaker 2: references I can get in there, so we'll this is
Speaker 2: gonna be a great show.
Speaker 3: All right.
Speaker 1: Well, the next question is not about goats or zombies
Speaker 1: or even vampires, but it is about bat.
Speaker 2: Ooh yes, so this is a question from Huntington. And
Speaker 2: this is also a question that involves a child, which
Speaker 2: I love, so yeah, and absolutely keep sending us questions
Speaker 2: that you and your kids have, or just questions your
Speaker 2: kids have, and so let's go ahead and hear the question.
Speaker 4: Now, Hi, Daniel and Kelly, We're probably blame more. Kelly,
Speaker 4: My son and I were reading about bats and the
Speaker 4: book said that bats have valves in their circulatory system,
Speaker 4: so the blood can't rush to their heads when they
Speaker 4: are upside down and make them dizzy. Why Some then.
Speaker 6: Asked why ol geckos get dizzy.
Speaker 4: I'm wondered if gecko's had something similar in their bodies
Speaker 4: to bats. I looked but couldn't find the answer and
Speaker 4: was hoping you could help out.
Speaker 1: Thank you boy, this is a great question. But before
Speaker 1: we understand like bats and geckos getting dizzy, you like,
Speaker 1: what does it mean to get dizzy? Anyway? Why do
Speaker 1: humans get dizzy? What is that all about?
Speaker 2: Yeah? Yeah, So when I get a question, one of
Speaker 2: the first things that I do is I like break
Speaker 2: the question into pieces, and then you have to check
Speaker 2: the premise of each part of the question. You know,
Speaker 2: not because you don't trust the list, but because, like
Speaker 2: you know one, you just want to make sure that
Speaker 2: everybody understands all the different parts of the question. So
Speaker 2: the first part of the question here is why do
Speaker 2: you get dizzy? And so what's implicit in this question
Speaker 2: here is that what makes you dizzy is the blood
Speaker 2: rushing to your head. And you know, maybe when the
Speaker 2: blood rushes to your head, it can't get back to
Speaker 2: your heart and so it doesn't get oxygenated, or maybe
Speaker 2: it's the change and the fluid pressure in your head.
Speaker 2: But actually getting dizzy is a very complicated thing and
Speaker 2: it can be caused by a lot of different things.
Speaker 2: So I was looking at like a MAO clinic website,
Speaker 2: and anxiety can make you dizzy? Really, yeah, apparently. And
Speaker 2: folks who study virtual reality and who try to make
Speaker 2: those virtual reality headsets have been sort of amazed at
Speaker 2: the many different ways that humans can become dizzy when you,
Speaker 2: you know, put them in a virtual reality setup and
Speaker 2: they'll report like, oh, no, that made me dizzy. Now
Speaker 2: I kind of want to puke, you know. No, you're underwater.
Speaker 2: Setup didn't calm me down. It made me feel like
Speaker 2: the world is spinning. And so anyway, being dizzy is
Speaker 2: a complicated thing. But let's look at two potential reasons
Speaker 2: for getting dizzy. Let's go ahead and dig into the
Speaker 2: one that's implied in the question first, which is blood
Speaker 2: rushing to your head.
Speaker 1: Blood rushing your head makes you dizzy. I always thought
Speaker 1: it was low blood pressure that made you dizzy.
Speaker 2: Yeah, So for me, when I stand up and you know,
Speaker 2: I have less blood in my head for a moment,
Speaker 2: that is what makes me dizzy. And I'll admit I
Speaker 2: shared some of this question on Blue Sky. I did
Speaker 2: get some responses from people being like, blood rushing to
Speaker 2: my head doesn't get me dizzy. It's blood rushing out
Speaker 2: of my head right, that makes me dizzy. And so
Speaker 2: it did seem like there was a general agreement that
Speaker 2: it's the getting up that makes you dizzy, not the
Speaker 2: blood rushing to the head that makes you dizzy. But
Speaker 2: there were folks trying to understand how maybe blood rushing
Speaker 2: to the head could make you dizzy, and the general
Speaker 2: consensus was that maybe what's happening is that when the
Speaker 2: blood rushes to your head, you know, one you get
Speaker 2: a pressure increase. Maybe that's a bit disorienting. But two,
Speaker 2: maybe the blood is pool in your head, and when
Speaker 2: it pools in your head, perhaps you get low oxygen
Speaker 2: because your body is used to gravity helping you get
Speaker 2: the blood down right, and so it's less good at
Speaker 2: pumping the blood away from your head when your head
Speaker 2: is in the wrong orientation, and so maybe it's not
Speaker 2: oxygenating as well under these conditions. And so maybe under
Speaker 2: these lower oxygen conditions and this higher pressure, it's making
Speaker 2: you sort of dizzy. I see, And again I'm not
Speaker 2: actually sure that that does cause dizziness. There was some
Speaker 2: debate about that, but the statement that was made in
Speaker 2: this book was that for bats this isn't a problem.
Speaker 2: Even though they sleep upside down because their circulatory system
Speaker 2: has valves, and these valves essentially keep the blood from
Speaker 2: pooling in the head, and so I think the idea
Speaker 2: here would be that they make it so the blood
Speaker 2: can't flow in the wrong direction and pool. And so
Speaker 2: that was the statement. And so the question was bats
Speaker 2: have these valves? Do geckos have the valves too?
Speaker 1: And I guess humans don't have these valves because humans
Speaker 1: can't be upside down for very long with other their
Speaker 1: heads popping or something.
Speaker 2: Right, Well, okay, so the equivalent of being upside down
Speaker 2: essentially would be like being in space. So when you
Speaker 2: are in space, if it's something you know that's right, yes, yeah, right.
Speaker 2: I was like, I don't know the answer to that,
Speaker 2: but I know the answer is something else. So when
Speaker 2: you're in space, the fluids shift up to your head
Speaker 2: and people do report feeling, you know, dizzy and disoriented.
Speaker 2: But that is partly maybe because of fluid shifts, but
Speaker 2: also because of this other thing that we're going to
Speaker 2: talk about in a moment, which is it messes up
Speaker 2: your vestibular system. Also, you're what system vestibular system hold on.
Speaker 2: That's the next thing we're going to talk about. Okay,
Speaker 2: But what we do with our fluid shifts is we
Speaker 2: pee a lot, and so our body releases a lot
Speaker 2: of fluids because our body is like, there's too much
Speaker 2: pressure up here. We're kind of confused about it, and
Speaker 2: so you urinate a lot, you lose a lot of
Speaker 2: the fluid. But we do think that you still have
Speaker 2: problems resulting from having too much fluid in your head. So,
Speaker 2: for example, astronaut vision gets worse over time, and we
Speaker 2: think partly that's because you do have more pressure in
Speaker 2: your head because of more fluids in your head, and
Speaker 2: we think that's pressing on your eyeballs. And people also
Speaker 2: report that there are wrinkles go away because with more
Speaker 2: fluid in their faces, it kind of presses out the
Speaker 2: wrinkles in their skin and so but they survive. So anyway,
Speaker 2: I think you can essentially have fluids pushing up on
Speaker 2: your head and survive. Your body has ways of dealing
Speaker 2: with it. They're kind of weird though.
Speaker 1: But bats have these special valves. And now we're on
Speaker 1: to geckos.
Speaker 2: Okay, but no, or do they?
Speaker 3: Oh?
Speaker 1: I see.
Speaker 2: So the first thing I do is I was like,
Speaker 2: all right, well, I'm gonna look it up. Do bets
Speaker 2: have these valves? And so I did find some websites
Speaker 2: like when I just did a plain Google search that
Speaker 2: we're saying like, oh, bats have these valves, blah blah blah.
Speaker 2: I was all right, well, I'm gonna find a scientific
Speaker 2: paper that talks about these valves. And I found mention
Speaker 2: of valves in the wings that like help them with flying,
Speaker 2: but I couldn't find mention of any valves related to
Speaker 2: helping them deal with being upside down. And in fact,
Speaker 2: I even found a paper that talked about how bats
Speaker 2: sleep upside down, and they were talking about how when
Speaker 2: they sleep upside down, there's an increase in their cranial
Speaker 2: pressure because fluids shift into their brain, which would suggest, yeah,
Speaker 2: they don't have these valves. And in fact, that paper
Speaker 2: did not talk about valves at all, And in fact,
Speaker 2: they talked about how if you hold bats upside down
Speaker 2: for even longer, their heart remodels to deal with the
Speaker 2: fact that, wow, it needs to accommodate being upside down.
Speaker 1: But why can it be such a deep mystery whether
Speaker 1: or not bats have these valves. Bats are not like
Speaker 1: rare or microscopic or invisible or shifting into zombies in
Speaker 1: the morning mist Like, why doesn't somebody just open up
Speaker 1: a bat carcass and look?
Speaker 2: Okay, Well, so here's the thing. Another valve story that
Speaker 2: I've heard a lot, and I'm going to answer your question,
Speaker 2: just stick with me for a second, is that giraffes
Speaker 2: have these valves also because they have these very long necks, right, yeah,
Speaker 2: and then when their head goes down to take a
Speaker 2: drink of water, they also need to have valves to
Speaker 2: make sure that their blood isn't rushing to their head
Speaker 2: and then rushing back. Right.
Speaker 1: I'm imagining some like complicated steampunk giraffe now energetically pumping
Speaker 1: stuff up and then pumping it back when the head
Speaker 1: turns around. This is a crazy system.
Speaker 2: Well, so the idea is that they've got these valves
Speaker 2: so that the blood like is essentially stopped from like
Speaker 2: pooling in the wrong spots. And so there was an
Speaker 2: experiment that had these giraffes that they anestatized and they
Speaker 2: held them up in the air in these braces, and
Speaker 2: then they essentially while they were anestatized, lifted their heads
Speaker 2: up and then put their heads down and then kept
Speaker 2: track of like where things were going.
Speaker 1: So they're like, they're like tilting these snoozing giraffes. What
Speaker 1: a hilarious experiment.
Speaker 2: Oh my gosh, I know, amazing, Right, And so then
Speaker 2: they were like monitoring changes in pressure and then like
Speaker 2: looking at like how the hearts were responding and stuff
Speaker 2: like that. And they then they looked and that like
Speaker 2: you know, where are the valves and stuff? And here
Speaker 2: it says his biological examinations revealed no valves in the
Speaker 2: carotid arteries, although such arterial vowels have been mentioned in
Speaker 2: more popular accounts such as the Encyclopedia Britannica online.
Speaker 1: Oh no, wow, you're calling out the Encyclopedia Britannica here, Kelly.
Speaker 2: I am not the paper is the paper is. And
Speaker 2: so I think that there has been like this vowelves
Speaker 2: deal with being upside down idea that has maybe escaped
Speaker 2: into the popular imagination.
Speaker 1: Another example of a gap between scientific and popular.
Speaker 2: Knowledge, maybe, And I'd love to know where this came from.
Speaker 2: And so anyway, so okay, basically what I'm saying is
Speaker 2: I watched a bunch of videos and the bat experts,
Speaker 2: when you ask them how bats managed to be upside down,
Speaker 2: they did not mention the valves. What they said was
Speaker 2: bats are so small it doesn't matter. Oh, they have
Speaker 2: strong hearts, and the distance between their heart and their
Speaker 2: head is small enough that they can just pump it
Speaker 2: and it's okay. Their hearts just get stronger if they
Speaker 2: need to. And they didn't say anything about valves. They
Speaker 2: just said they're small enough, doesn't matter. And I couldn't
Speaker 2: find any evidence of valves.
Speaker 1: This is a fascinating crossover between physics and biology. Actually,
Speaker 1: it's not like you can take the same biological system
Speaker 1: and just like scale it up by a thousand or
Speaker 1: scale it down by a thousand and assume it's going
Speaker 1: to operate the same way, because like pressure and volume
Speaker 1: and surface area and mass, these things all grow differently
Speaker 1: with size, and so they'll be like totally out of
Speaker 1: whack if it gets too big or too small. So
Speaker 1: you're saying the same system, which is susceptible to getting
Speaker 1: dizzy and having blood pooling at our scale or maybe
Speaker 1: even giraffes, doesn't happen for bats.
Speaker 2: I think that is the answer, because like the bat experts,
Speaker 2: we're not mentioning the valves. I couldn't find the valves
Speaker 2: in the literature. If anybody wants to write into correct me,
Speaker 2: please tell me. And then in a future Listener Questions episode,
Speaker 2: at the beginning of the episode, I will say, there
Speaker 2: is evidence of the valves and I just missed it.
Speaker 1: Send us proof of the alleged bat valves.
Speaker 2: Well, I mc daniel and I would always like to
Speaker 2: be corrected if we're wrong about something, So please let
Speaker 2: us know.
Speaker 1: Don't be shy right in with your well, actually comment.
Speaker 2: Please you please, absolutely, okay. And so another reason that
Speaker 2: we get dizzy is because we have this system in
Speaker 2: our head that helps us figure out like balance and
Speaker 2: where we are in the universe in this system. So
Speaker 2: I use the word earlier, and I will, for Daniel's sake,
Speaker 2: avoid biology jargon from here on out after I say
Speaker 2: the word one more time.
Speaker 1: Is this vestibular?
Speaker 2: Vestibular? It's in your inner ear and it's a system
Speaker 2: of tubes filled with fluid, and when you move, like
Speaker 2: when you rotate your head side to side, the fluid
Speaker 2: starts going around the tube.
Speaker 1: It's an accelerometer.
Speaker 2: It is, Yeah, it's like an accelerometer.
Speaker 1: It is an accelerometer.
Speaker 2: It is an accelerometer, and your brain detects that the
Speaker 2: fluid is going around in that tube, and sometimes so
Speaker 2: like if you start spinning in place over and over
Speaker 2: and over again, the fluid in that tube is going
Speaker 2: to start spinnings and spinning and spinning and spinning. And
Speaker 2: then if you stop spinning all of a sudden, it's
Speaker 2: going to take a little while for that fluid to
Speaker 2: stop spinning. And so for a little while there, your
Speaker 2: brain still gets the message that you are spinning, while
Speaker 2: your eyes are telling your brain, I am not spinning.
Speaker 2: And we think that that disconnect between what your ear
Speaker 2: is telling your brain and what your eyes are telling
Speaker 2: your brain is part of why you feel dizzy, because
Speaker 2: you're getting conflicting information. And to be honest, we don't
Speaker 2: one hundred percent understand dizziness.
Speaker 1: Has nobody done the experiment of taking a bunch of
Speaker 1: giraffes and putting them on a merry go around and
Speaker 1: then you don't even remember about whether they got dizzy.
Speaker 1: That seems like that would settle the question.
Speaker 2: Yeah, we need a lot of money for that experiment.
Speaker 2: Probably call us that's right, that's right, we will take
Speaker 2: your money. But it does suggest actually that if you
Speaker 2: spin in the opposite direction, that could slow the fluid down,
Speaker 2: and that might be a way to help your dizziness
Speaker 2: go away faster, which is kind of a fun experiment.
Speaker 1: Medical advice people, not medical advice.
Speaker 2: Kelly is never giving official medical advice. I am not
Speaker 2: that kind of doctor.
Speaker 1: If your kid is dizzy, do not spin them the
Speaker 1: other way on our No, it's just an interesting thought experience.
Speaker 2: That's right, that's right. And so we've got tubes that
Speaker 2: go in multiple different directions to accommodate for spinning in
Speaker 2: multiple different directions. And then we also have a system
Speaker 2: of essentially crystals that are tied to hairs, and this
Speaker 2: tells you about moving it like forward and backwards. And
Speaker 2: so if you go forward really quick, then those crystals
Speaker 2: are gonna get pushed forward and they'll pull on the hairs.
Speaker 2: And that's how your body knows that, like, oh, we
Speaker 2: just kind of moved forward, and that sends a message
Speaker 2: to your brain that we move forward.
Speaker 1: No, we accelerated, Kelly, we accelerate.
Speaker 2: We accelerate, thank you, thank you.
Speaker 1: Your ear can tell that you're moving or that heads
Speaker 1: velocity can only measure acceleration. It's like a bowling ball
Speaker 1: in the back of a truck, right it's seventy miles
Speaker 1: an hour in the highway. The bowling ball doesn't move,
Speaker 1: but if you hit the brakes, then the bowling ball
Speaker 1: rolls to the front. So even if you didn't know
Speaker 1: you're a lo and you couldn't measure your acceleration in
Speaker 1: any other way, if you watch the ball, you can
Speaker 1: tell if you're accelerating in any direction. And that's what's
Speaker 1: happening in your ear. It's an accelerometer.
Speaker 2: Okay, yes, So we've got two different kinds of accelerometers
Speaker 2: in our ears, and geckos and bats have these as well.
Speaker 2: Presumably geckos and bats could get dizzy also if they
Speaker 2: moved too quickly and messed with these kinds of accelerometers.
Speaker 2: And so I'm guessing they have the same kinds of constraints,
Speaker 2: because I did look up do geckos, for example, also
Speaker 2: have semicircular ducks, and they do also have these kinds
Speaker 2: of semicircular canals, and so you know, I think they
Speaker 2: could possibly also get dizzy. They've got the same system
Speaker 2: that we have.
Speaker 1: I think I might have a special mutation because I
Speaker 1: tend to get dizzy when I hear too many biological
Speaker 1: Latin names.
Speaker 2: You know, I wanted to talk to you about that
Speaker 2: because you told me that you wanted me to say
Speaker 2: things like beetle one and beetle two, And I was
Speaker 2: thinking that from now on, we're not saying muons, gluons,
Speaker 2: no fermions, no bosons. It's particle one, particle two.
Speaker 3: Uh.
Speaker 2: And what's that's right? Yeah, we're gonna we're gonna simplify
Speaker 2: all of this from from now on. Okay, So anyway
Speaker 2: to finally answer the question, why don't geckos get dizzy?
Speaker 1: Yeah, Uh, nobody knows, that's right.
Speaker 2: Who knows. I think they might get dizzy. They I
Speaker 2: think they have a similar semi circular canal system that
Speaker 2: we have, and sometimes we get dizzy. Sloths hang upside down.
Speaker 2: And I think the answer for why they don't get
Speaker 2: dizzy is they move kind of slowly. That's an answer
Speaker 2: I found online. So maybe geckos also have to be
Speaker 2: a little careful about moving slowly sometimes. But if they're
Speaker 2: running away from a predator, maybe they do get a
Speaker 2: little bit dizzy from time to time, but they just
Speaker 2: have to deal with it like the rest of us.
Speaker 2: I don't know about this valve thing. I didn't find
Speaker 2: evidence for it. But I'm welcoming people to correct me.
Speaker 2: And thanks for this fun question. I enjoyed reading about
Speaker 2: semi circular canals and the circulatory systems of bats and geckos,
Speaker 2: and this took me down so many different rabbit holes, fascinating.
Speaker 2: It was a lot of fun.
Speaker 1: That's one of my favorite things about listener questions is
Speaker 1: how can we learn in digging up the answers?
Speaker 2: Absolutely all right, let's see if I gave a moderately
Speaker 2: satisfactory answer to Huntington and your son. Let's see how
Speaker 2: this went.
Speaker 4: So what do you think?
Speaker 6: That's pretty good? That's pretty good.
Speaker 4: It's pretty good.
Speaker 6: I'm wanted to I mean, I can't good. Okay, this
Speaker 6: is googgs leazing. I need to catch Thank.
Speaker 5: You for breaking down the question and exposing the assumptions
Speaker 5: we didn't even know we were making. I'm honestly surprised
Speaker 5: to learn that bats and giraffes don't have valves like
Speaker 5: we had read about. I guess that is a lesson
Speaker 5: about trusting and verifying the information we read in popsie books.
Speaker 5: I guess I shouldn't have been surprised to learn that
Speaker 5: for something we've all experienced. There is not a clear
Speaker 5: explanation for dizziness, but I still was. My son enjoyed
Speaker 5: the answers and was very satisfied with them, something that
Speaker 5: I have never been able to provide with my answers.
Speaker 5: So thanks again and keep up the great work.
Speaker 2: All right, Worshock almost got out of the barn. Lottie's
Speaker 2: looking a bit uncomfortable. I'm gonna be sitting with her
Speaker 2: for the hour after we're done. But all right, we're
Speaker 2: back to Daniel and Kelly's extraordinary universe and the extraordinarily
Speaker 2: fun watching of goats kidding.
Speaker 1: In the brief interval before Kelly's Good gives birth, we're
Speaker 1: gonna try to answer a complicated question about what's going
Speaker 1: on inside spinning black holes. Here's a fun question I
Speaker 1: got from Joe.
Speaker 3: Hi, Daniel and Kelly. This question is more for Daniel.
Speaker 3: I understand that the inner workings of a black hole
Speaker 3: are a mystery to us, But I heard something about
Speaker 3: a couchy manifold. It's some kind of inner horizon, and
Speaker 3: I'm wondering how these complex mathematics might be explained.
Speaker 2: Oh, this is fun. I don't think I know what
Speaker 2: a couchy manifold is did I say it right?
Speaker 1: Koushi? Yeah?
Speaker 2: Caushi? Well no are The answer is no because that's
Speaker 2: not what I said. But you're nice.
Speaker 6: I like that.
Speaker 1: We can call it kouchy if you prefer to. Imagine
Speaker 1: like sitting on a couch while understanding these things.
Speaker 2: Oh yeah, I like sitting on a couch while understanding
Speaker 2: the universe. So what is a cat Oh no, I
Speaker 2: already forgot Koushi caushe So.
Speaker 1: A cauchy horizon is where causality breaks down. And this
Speaker 1: is going to be really surprising because we're talking about
Speaker 1: classical physics, which is famous for being deterministic, which means that,
Speaker 1: like the past determines the future. You have a bunch
Speaker 1: of billiard balls, you shoot them at each other, they
Speaker 1: bounce off at some angle. They're going to do that
Speaker 1: every time. Because the past determines the future. There's no fuzziness,
Speaker 1: there's no randomness. We're ignoring quantum mechanics completely for this answer.
Speaker 1: Imagine we live in a universe ruled by classical physics.
Speaker 1: Usually we think, and we talked about this on the
Speaker 1: Weather Modeling episode. If you know everything about the universe,
Speaker 1: like where all the particles are where they're going their
Speaker 1: exact stated universe. Plus you know the rules of the universe,
Speaker 1: meaning like how things interact and how they will bounce
Speaker 1: off of each other, then you can predict the future. Right,
Speaker 1: So perfect knowledge of the current state plus perfect knowledge
Speaker 1: of the rules, you should be able to predict the future.
Speaker 1: That's causality in a nutshell.
Speaker 2: Sure, but I thought we also determined that it was
Speaker 2: also a little too complicated and we couldn't actually predict
Speaker 2: the future. But technically we should be able to if
Speaker 2: we could do those complicated equations.
Speaker 1: Yeah, okay, absolutely, if you had perfect knowledge of the universe,
Speaker 1: which you never do, not even because of quantum mechanics,
Speaker 1: but because there's just too much information. Like in the
Speaker 1: case of the weather, we don't have enough booies out
Speaker 1: in the ocean, and we don't have enough airplanes with
Speaker 1: thermometers on them. We don't have all that information. But
Speaker 1: in principle, that's a practical problem and engineers could overcome it.
Speaker 1: The information exists and is accessible in a classical universe,
Speaker 1: which isn't our universe. So there's lots of reasons why
Speaker 1: this could never happen. But if you imagine a classical universe.
Speaker 1: It is possible in principle to have that information. It
Speaker 1: exists and in that classical universe, because we've assumed the
Speaker 1: universe is classical and that there are rules, and if
Speaker 1: we knew those rules, then in principle, we could perfectly
Speaker 1: predict the future.
Speaker 2: Got it.
Speaker 1: Okay, that's the same, But there are some caveats, right,
Speaker 1: and those caveats are what we're talking about today. Cave
Speaker 1: At number one is about the speed of light, and
Speaker 1: it's not actually directly related to the country horizon, but
Speaker 1: it's a good warm up because what you actually need
Speaker 1: to bridge the future is not all the knowledge in
Speaker 1: the universe about what's happening. Some things in the universe
Speaker 1: can't affect your immediate future. The only thing that can
Speaker 1: affect the immediate future is parts of the universe where
Speaker 1: light has had time to get here since that event. So,
Speaker 1: for example, if there's an alien right now in Alpha
Speaker 1: Centauri and they're aiming a death ray at us, and
Speaker 1: they fire the button boom right now to shoot that
Speaker 1: death ray at us, it cannot affect what's going to
Speaker 1: happen right here on Earth in the next millisecond, because
Speaker 1: there isn't time for that death ray to get here.
Speaker 1: So we say in physics, it's not part of our
Speaker 1: past light cone. Our past light cone is everything that
Speaker 1: can affect the immediate future. And because there's a speed
Speaker 1: limit on infrom and signaling, then things that can't get
Speaker 1: here are outside of that past like cone.
Speaker 2: Okay, I understand. It still feels like there's an approximately
Speaker 2: infinite number of things we can't measure, and we've knocked
Speaker 2: a small fraction of them out. But but but okay,
Speaker 2: but all right, there's some things now we don't have
Speaker 2: to worry about.
Speaker 1: But of course that death ray will eventually arrive at Earth,
Speaker 1: and in a couple of million years, that alien shooting
Speaker 1: that deathray, that event will be in the past like
Speaker 1: cone of our future. Right, So it's a time dependent thing.
Speaker 1: Our past like cone, is not just a location. It's
Speaker 1: locations and times. It's events in space time. Some of
Speaker 1: those things that are outside our past like cone right
Speaker 1: now can be in the past like cone of people
Speaker 1: in our future. Right because aliens, if they shoot that
Speaker 1: death ray, can kill our great great great great great
Speaker 1: great great great grandchildren.
Speaker 2: Okay, got it? So wait, what is the question that
Speaker 2: we're trying to answer, then are we trying to answer
Speaker 2: who's going to die? Because then it seems very relevant
Speaker 2: to them.
Speaker 1: So we're trying to answer what is a Cauchhi horizon?
Speaker 1: And a Cauchhi horizon is a place where you cannot
Speaker 1: predict the future? Okay, all right, And they might wonder
Speaker 1: how does that happen? What's going on? Classical physics, things
Speaker 1: are deterministic. In fact, they only depend on a subset
Speaker 1: of the universe, your past light cone. How is it
Speaker 1: possible to have in classical physics a setup where you
Speaker 1: can't predict the future. And the answer is if you
Speaker 1: have something in your past light cone like a singularity,
Speaker 1: which is like a breakdown of classical physics, something that's unpredictable.
Speaker 2: Okay.
Speaker 1: The short answer is that a Caushi horizon is what
Speaker 1: happens inside a spinning black hole where there's a singularity
Speaker 1: inside your past light cone. And a singularity is not
Speaker 1: something you can fold into your equations because it has
Speaker 1: an infinity in it, and so it makes it impossible
Speaker 1: to predict the future. Okay, So let's dig into that
Speaker 1: a little bit more and understand why that happens. And
Speaker 1: to do that, let's remember what a black hole is anyway.
Speaker 1: A black hole in popular science is often like a
Speaker 1: thing in space that has really strong gravity and sucks
Speaker 1: everything up right. But actually gravity is not a force,
Speaker 1: it's curvature of space. Time objects are moving to follow
Speaker 1: that curvature, and black holes are just places with really
Speaker 1: really strong curvature because you have a lot of mass
Speaker 1: and a small area, so the curvature gets really really strong,
Speaker 1: and it gets so strong that you get an event horizon.
Speaker 1: Event horizon is like a dotted line in space, and
Speaker 1: anything that goes inside the event horizon will never leave
Speaker 1: the event horizon. Okay. So that means that a particle
Speaker 1: inside the event horizon, its entire future is in the
Speaker 1: event horizon. There's no place in the event horizon and
Speaker 1: no particle trajectory you could even come up with that's
Speaker 1: ever going to leave the event horizon, okay. And the
Speaker 1: reason is fascinating because the curvature inside the black hole
Speaker 1: is so strong that the singularity inside of the black
Speaker 1: hole is not like a location in space. Space and
Speaker 1: time get twisted so that singularity is a location in time.
Speaker 1: You can think of it like inside the black hole,
Speaker 1: space is one directional, so the singularity is always in
Speaker 1: your future. No matter what you do, every path leads
Speaker 1: to the singularity. So the singularity is not like a
Speaker 1: place in space you can like fly by and try
Speaker 1: to avoid. It's not like the grocery store. You can
Speaker 1: go to it or you cannot go to it. It's
Speaker 1: like next Tuesday. There's nothing you can do to avoid
Speaker 1: Next Tuesday. It's coming. You can't pass it, you can't
Speaker 1: go around it. It's in your future.
Speaker 2: Okay. So before we were talking about being in a
Speaker 2: light cone where aliens were going to destroy us, Yeah,
Speaker 2: and there could be a singularity, and now we're talking
Speaker 2: about singularities in a black hole.
Speaker 1: Yeah, and so the connection is so remember we're answering
Speaker 1: the question what is a Cowshie horizon. Cawshi horizon is
Speaker 1: a place in space where predictions break down, and they
Speaker 1: break down because you have a singularity in your past
Speaker 1: like cone, it's like in your history. And singularities are infinities.
Speaker 1: You can't use them to calculate. And it's a special
Speaker 1: kind of singularity because the normal kind of singularity we're
Speaker 1: talking about, the kind that are inside vanilla black holes,
Speaker 1: are not like that. They're in your future. A singularity
Speaker 1: inside a vanilla black hole can never be in your
Speaker 1: past like cone. It's always in your future, right, It
Speaker 1: can't affect anything that's happening. It's always something that's going
Speaker 1: to happen to you. So how do you get a
Speaker 1: singularity in your past like cone so you can disrupt
Speaker 1: your predictions of the future. For that, you need a
Speaker 1: special kind of black hole. You need a rotating black hole.
Speaker 1: Black holes we've been talking about so far just a
Speaker 1: dense point in space. Curvature is really really strong. Space
Speaker 1: is bent so that the singularity is in your future.
Speaker 1: But if you spin that black hole, you get a
Speaker 1: very different kind of space time structure. Something that happens
Speaker 1: in Einstein's gravity, which differentiates it from Newton's gravity. Newton
Speaker 1: says gravity's a force. Einstein says it's a curvature. Most
Speaker 1: of the time they give the same answers, but they
Speaker 1: differ when the mass is spinning. Newton says something that's
Speaker 1: spinning has the same force as something that's not spinning.
Speaker 1: It doesn't make any difference, like the force on the
Speaker 1: Moon from the Earth doesn't depend on the fact that
Speaker 1: the Earth is spinning. According to Newton, Einstein says, actually,
Speaker 1: gravity is curvature in response to energy. Spinning is a
Speaker 1: kind of energy, And he's got all these complicated equations.
Speaker 1: It's like sixteen of them in a big tensor. So
Speaker 1: the direction matters, and it causes a twist in space
Speaker 1: time itself. So it's a very complicated response to spinning.
Speaker 1: And so what it means is that inside a spinning
Speaker 1: black hole there's two horizons. There's still the event horizon,
Speaker 1: just like a normal black hole. Once you fall in
Speaker 1: the event horizon, there's an inner horizon that's the Cauchy horizon.
Speaker 1: The Cauhi horizon is still in your future. So you
Speaker 1: fall into the spinning black hole, then there's no way
Speaker 1: to avoid falling in even further till you get past
Speaker 1: the Kaushi horizon. Once you're inside the Caushi horizon, then
Speaker 1: the spinning singularity at its heart is not in your future.
Speaker 1: It's a different kind of singularity. It's actually avoidable. You
Speaker 1: can like be in an orbit around that singularity. It's
Speaker 1: not just in your future. It's more like the grocery
Speaker 1: store than like next Tuesday. The problem is that that
Speaker 1: means it can be in your past. It can affect
Speaker 1: things that happen to You can like send out signals
Speaker 1: from the singularity which can arrive at you and change
Speaker 1: what happens to you. But nobody knows how to calculate
Speaker 1: what signals what a singularity send out. It's an infinity,
Speaker 1: it's a breakdown. So inside the Cashi horizon, you have
Speaker 1: this thing which can be in your past, but it's
Speaker 1: also sort of nonsense, like you don't know how to
Speaker 1: calculate it, and because of that, it means you can't
Speaker 1: predict what's going to happen. So you have a situation
Speaker 1: in the universe where you have something in your past
Speaker 1: like cone which can affect your future. We're not talking
Speaker 1: about faster than like communication. But also you don't know
Speaker 1: how to calculate it, so you can't predict your future.
Speaker 1: It's like you were saying before, if you don't have
Speaker 1: all the initial information, if you can't describe the current
Speaker 1: state of events, you can't predict the future. Well, what
Speaker 1: if there's something that's just indescribable in your current state
Speaker 1: of events, then you can't predict the future. So the
Speaker 1: Caushi horizon is the part of space time inside a
Speaker 1: spinning black hole where you have this singularity in your past,
Speaker 1: and so predictions are just off, like you just cannot
Speaker 1: make them. It's amazing because you think of classical physics
Speaker 1: as predictable, deterministic, like a clockwork universe, But there are
Speaker 1: places where it goes crazy.
Speaker 2: Does every black hole have a singularity in it?
Speaker 1: Every black hole has a singularity in it according to
Speaker 1: general relativity. Now we don't think general relativity is correct.
Speaker 1: In fact, it probably breaks down at exactly this place,
Speaker 1: the singularity. So in reality in our universe, are there
Speaker 1: places where you can't predict the future? Probably not, because
Speaker 1: all of this is probably wrong, and we need quantum
Speaker 1: gravity to describe what's going on here. And in fact,
Speaker 1: singularity is an example of why we think general relativity
Speaker 1: is probably wrong, because singularities, they are very existence is
Speaker 1: in conflict with quantum mechanics, and quantum mechanics itself is
Speaker 1: actually kind of deterministic. It doesn't predict the exact outcome,
Speaker 1: but it predicts the probabilities in a very deterministic and
Speaker 1: specific way. So this would also mess up the determinism
Speaker 1: of quantum mechanical probabilities. So most is just think, yeah,
Speaker 1: this is interesting little quirk in the calculations when you
Speaker 1: assume the universe is classical, but nobody thinks that it is,
Speaker 1: and so it's probably irrelevant to reality. But it is
Speaker 1: a fascinating little corner of general relativity where predictions are
Speaker 1: just not possible. And that's why spinning black holes, which
Speaker 1: are probably in reality much more common than non spinning
Speaker 1: black holes, have this two stage structure. They have an
Speaker 1: event horizon and the caushi horizon.
Speaker 2: Okay, So, given what you just said, if you had
Speaker 2: to guess if any of this stuff is actually going on,
Speaker 2: would you guess zero? Okay? Got it? Okay?
Speaker 1: Yeah, all right, Joe, thank you for your curiosity about
Speaker 1: spitting black holes and inner horizons and Cawshi manifolds. Let
Speaker 1: me know if that answered your question.
Speaker 3: Wow, No, I think I got about eighty percent of that.
Speaker 3: A spinning black hole with an event horizon where causality
Speaker 3: breaks down. That's fade worse than spaghetification, I think. But
Speaker 3: maybe spaghetification is the future that we can't predict with certainty,
Speaker 3: although I think I'd be pretty certain to avoid the
Speaker 3: caushi horizon.
Speaker 2: Thanks a lot, Thank you everyone for sharing your curiosity
Speaker 2: with us. If you have a question you'd like to
Speaker 2: send our way, send it at questions as Danielankelly dot org.
Speaker 2: We would love to interact with you.
Speaker 1: Please do write to us. We're not just saying.
Speaker 2: That, and we would massively appreciate it if you'd be
Speaker 2: willing to leave us a review on Spotify, Apple, on
Speaker 2: whatever podcast app it is that you listen to us on.
Speaker 2: It helps other people find the show.
Speaker 1: And if you reviewed us several years ago and you're
Speaker 1: thinking that doesn't apply to me, come back review us
Speaker 1: again to the new show.
Speaker 2: Thanks