Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions #34

Transcript

Listener Questions #34 · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: If you get up early to walk the dog, you
• 0:10
  Speaker 1: might wonder why all the morning.
• 0:12
  Speaker 2: Fog does blood rush to the head of upside down bats?
• 0:17
  Speaker 2: Or do adaptations help deal with all of that?
• 0:20
  Speaker 1: A spinning black hole is quite the disgrace. It breaks
• 0:24
  Speaker 1: causality all over the place.
• 0:27
  Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's
• 0:30
  Speaker 2: answers will help make it right.
• 0:33
  Speaker 1: Welcome to listener questions number thirty four on Daniel and
• 0:37
  Speaker 1: Kelly's Extraordinary Universe.
• 0:53
  Speaker 2: Hello, I'm Kelly Waiter Smith. I study parasites and space,
• 0:56
  Speaker 2: and I'm excited that today we've got nature, We've got
• 1:00
  Speaker 2: we've got black holes, We've got all the good stuff
• 1:03
  Speaker 2: on the show today.
• 1:04
  Speaker 3: Hi.
• 1:04
  Speaker 1: I'm Daniel. I'm a particle physicist, and I almost certainly
• 1:08
  Speaker 1: don't have a goat giving birth in my backyard.
• 1:11
  Speaker 2: Yeah, that's right. Daniel today was like, Hey, Kelly, do
• 1:13
  Speaker 2: you want to record an hour early? And I was like, well,
• 1:16
  Speaker 2: first I have to see if my goat needs to
• 1:18
  Speaker 2: have a bowel movement or if she's about to give
• 1:20
  Speaker 2: birth early. We've all been there for moms. But but yeah,
• 1:25
  Speaker 2: I and actually I think it was I think it
• 1:28
  Speaker 2: could be both.
• 1:29
  Speaker 1: Wow.
• 1:29
  Speaker 2: So between every segment today, I'm going to run out
• 1:31
  Speaker 2: and check on my goat and see how she's doing.
• 1:33
  Speaker 1: That's right. You could all be witnesses to the miracle.
• 1:35
  Speaker 2: Of life, that's right. Yeah, I know, or a goat
• 1:38
  Speaker 2: pooping good Yeah, or both or both, probably both, because
• 1:41
  Speaker 2: it's biology.
• 1:42
  Speaker 1: I guess both count as the miracle of life.
• 1:44
  Speaker 4: Right.
• 1:44
  Speaker 1: They're both important functions, that's right.
• 1:48
  Speaker 2: You know, when you don't poop, you kind of wish
• 1:51
  Speaker 2: you were dead, I'm guessing. So, so you need both,
• 1:54
  Speaker 2: you need both?
• 1:55
  Speaker 1: All right. Well that's the backdrop. But in the foreground
• 1:58
  Speaker 1: today we are addressing your curiosity. We are talking about
• 2:01
  Speaker 1: questions you have about how the universe works, from six
• 2:04
  Speaker 1: year old wondering about fog on the way to school
• 2:07
  Speaker 1: all the way to the inner horizons of spinning black holes.
• 2:10
  Speaker 2: And I got to tell you, as of today, I
• 2:12
  Speaker 2: am changing my strategy a little bit, because my strategy
• 2:14
  Speaker 2: has been I take questions from listeners that I do
• 2:18
  Speaker 2: not know the answer to, that are hard that I
• 2:20
  Speaker 2: can't figure out quickly, and I put them on my
• 2:23
  Speaker 2: list and those are the ones that end up on
• 2:24
  Speaker 2: the show. And now I only have questions that take
• 2:27
  Speaker 2: me like ten hours or more to answer on my list.
• 2:32
  Speaker 2: And so next time someone asked me a real softball question,
• 2:35
  Speaker 2: I'm throwing that on my list for a listener question
• 2:38
  Speaker 2: episode because I need some easy ones, sort of like
• 2:41
  Speaker 2: sprinkled in there, because this one was a bit.
• 2:45
  Speaker 1: Tough unsolved mysteries of biology. Yeah, I did that too,
• 2:51
  Speaker 1: but I also mix in easier questions that I think
• 2:54
  Speaker 1: a lot of people will be interested in answer, or
• 2:57
  Speaker 1: that I think will be fun to joke about with you.
• 2:59
  Speaker 2: Oh oh, those are all good strategies. Yeah, all right, Well,
• 3:02
  Speaker 2: we learn from each other as much as we learn
• 3:05
  Speaker 2: from the listeners, which is lovely. We're all learning from
• 3:07
  Speaker 2: each other. What a great community.
• 3:08
  Speaker 1: And today we're starting with a question from a six
• 3:11
  Speaker 1: year old. This is a future scientist, folks, somebody who
• 3:14
  Speaker 1: looks out in the world and wants to understand what's
• 3:17
  Speaker 1: going on. So let's get started with our first question.
• 3:21
  Speaker 5: Hey, Daniel Kelly, So our son just turns six and
• 3:24
  Speaker 5: he's starting kindergarten this year.
• 3:26
  Speaker 2: With that, we've been getting up earlier in the mornings
• 3:28
  Speaker 2: and he started to notice something.
• 3:31
  Speaker 6: By Jeja Yeho FuG and money.
• 3:34
  Speaker 2: This is such a great question. I love this question.
• 3:37
  Speaker 2: And also I'm particularly excited about fog since we moved
• 3:40
  Speaker 2: out to a farm that has these big fields, because
• 3:44
  Speaker 2: the fog will sometimes roll across the fields, and I
• 3:48
  Speaker 2: am really into zombie movies, and every once in a
• 3:50
  Speaker 2: while I'll look out and as the fog rolls across
• 3:52
  Speaker 2: the field, I'm like the zombies. They must be coming,
• 3:55
  Speaker 2: because it looks like the setting for a zombie movie.
• 3:58
  Speaker 2: And then I'm a little disappointed because this Bomi's never
• 4:00
  Speaker 2: come up out of the fog and I never get
• 4:02
  Speaker 2: to use my taekwondo skills. But that's probably better i'd
• 4:05
  Speaker 2: be dead. So all right, Daniel, where does the fog
• 4:09
  Speaker 2: come from?
• 4:09
  Speaker 1: It's foggy in the morning because fog forms when air
• 4:13
  Speaker 1: gets colder, and so at night it gets colder because
• 4:16
  Speaker 1: it's not as much sunshine, and so it gets foggy.
• 4:19
  Speaker 1: That's the answer I'm aiming at a six year old.
• 4:21
  Speaker 1: But then, of course we can dig in deeper into
• 4:23
  Speaker 1: the science for the rest of the listeners. Does that
• 4:26
  Speaker 1: make sense?
• 4:26
  Speaker 2: I guess I don't know why it getting colder should
• 4:30
  Speaker 2: make it foggy, And I bet the six year old
• 4:32
  Speaker 2: is also saying, give me a better answer. Daniel. This
• 4:36
  Speaker 2: is not why I listen to dKu.
• 4:40
  Speaker 1: All right, fair point, let's dig in. So what is
• 4:43
  Speaker 1: fog anyway? Fog is water. Water can be a solid ice,
• 4:47
  Speaker 1: it can be a liquid that's what we usually call water,
• 4:50
  Speaker 1: or it can be vapor. Okay, that vapor is invisible
• 4:53
  Speaker 1: and he can mix with the air. Or we sometimes
• 4:56
  Speaker 1: say the air is holding that water. You can't see
• 4:59
  Speaker 1: that water when it's but you can tell that it's there,
• 5:02
  Speaker 1: like when you go outside. The air can be humid,
• 5:04
  Speaker 1: which feels sticky, or if you're lucky enough to live
• 5:07
  Speaker 1: in California, the air can feel fairly dry, right, or
• 5:10
  Speaker 1: like I visited Houston recently, where the air is like chewy.
• 5:13
  Speaker 2: Yeah, yeah, I don't miss that about Houston. Really gotta
• 5:17
  Speaker 2: be honest exactly.
• 5:19
  Speaker 1: But if there's more water then the air can hold,
• 5:23
  Speaker 1: then it condenses out and you get droplets, clouds, steam, fog,
• 5:28
  Speaker 1: this kind of stuff. So the air is kind of
• 5:30
  Speaker 1: like a sponge and that it can hold some water,
• 5:33
  Speaker 1: but if you put too much into it, it's gonna
• 5:35
  Speaker 1: leak out. And so when there's more water in the
• 5:37
  Speaker 1: air that it can hold, then you get fog or
• 5:40
  Speaker 1: then you get rain. And that's called the dew point.
• 5:43
  Speaker 1: The dew point is the temperature where the air is
• 5:46
  Speaker 1: fully saturated, the relative humidity is one hundred percent. It
• 5:49
  Speaker 1: can't hold anymore. And if you go below the dew point,
• 5:53
  Speaker 1: then you get dew where the water like precipitates out
• 5:56
  Speaker 1: into little droplets and forms on plants and stuff.
• 5:59
  Speaker 2: And that's what we call do okay, all right, So
• 6:01
  Speaker 2: at night it gets colder, and the reason that matters
• 6:05
  Speaker 2: is because cold air can hold less water, right.
• 6:08
  Speaker 1: That's right. Warmer air can hold more water, and colder
• 6:12
  Speaker 1: air can hold less water. So if you have a
• 6:14
  Speaker 1: bunch of air and it's got some water in it
• 6:16
  Speaker 1: and it's all fine, and it can handle that much
• 6:18
  Speaker 1: water you're like seventy five percent humidity. Then as you
• 6:21
  Speaker 1: cool that air down, it can't hold as much water.
• 6:24
  Speaker 1: And at some point it passes the temperature where it's
• 6:26
  Speaker 1: at one hundred percent humidity. It's the temperature at which
• 6:29
  Speaker 1: it's holding all the water than it can. Then you
• 6:31
  Speaker 1: pass that, you go even colder, and it can't hold
• 6:34
  Speaker 1: that water anymore, so it comes out of the air
• 6:36
  Speaker 1: and it makes fog. So fundamentally what's happening here is
• 6:40
  Speaker 1: as you say, how much water the air can hold
• 6:43
  Speaker 1: depends on the temperature, and you might wonder, like why
• 6:46
  Speaker 1: is that? Is it related to, for example, how much
• 6:49
  Speaker 1: like salt you can dissolve into water, which also depends
• 6:51
  Speaker 1: on temperature, Like you put salt into water. You can
• 6:54
  Speaker 1: dissolve more salt and water when it's hot than when
• 6:57
  Speaker 1: it's cold.
• 6:58
  Speaker 2: Right, Okay, So I guess what I'm wondering is, all right,
• 7:00
  Speaker 2: so you're outside on a particular kind of day where
• 7:04
  Speaker 2: there's a lot of moisture in the air and it's warm,
• 7:07
  Speaker 2: and so like, what kind of warm day would result
• 7:11
  Speaker 2: in the air holding as much water as possible? Like
• 7:15
  Speaker 2: would a warm day always hold as much water as
• 7:17
  Speaker 2: possible or does it need to have like rained recently
• 7:21
  Speaker 2: and now there's more water in the air and so
• 7:23
  Speaker 2: it's holding as much water as it can. Basically, my
• 7:26
  Speaker 2: question is why isn't there fog every single morning? And
• 7:29
  Speaker 2: so I'm trying to figure out the conditions that result
• 7:32
  Speaker 2: in one hundred percent water being in the air.
• 7:37
  Speaker 1: Yeah, cool question, So why does it happen sometimes and
• 7:40
  Speaker 1: not other times? So in order for this to happen,
• 7:43
  Speaker 1: you need moist air, you need water to be in
• 7:45
  Speaker 1: the air, and that's why you often see fog like
• 7:48
  Speaker 1: near valleys or near the ocean or near lakes, or
• 7:51
  Speaker 1: after rainy days or in fall when the nights are
• 7:55
  Speaker 1: really really long, so it gets colder at night than
• 7:58
  Speaker 1: it does in the summer. So yeah, you need a
• 8:01
  Speaker 1: source of that water. So if it's rained, or if
• 8:04
  Speaker 1: you have a valley with a river or a lake
• 8:05
  Speaker 1: or something, you need a source of that water in
• 8:08
  Speaker 1: order to make it moist. So you ask, like, what
• 8:10
  Speaker 1: kind of day is going to be like hot and
• 8:13
  Speaker 1: moist something where it rained or where there's a nearby
• 8:16
  Speaker 1: body of water to evaporate from. You need that source
• 8:20
  Speaker 1: of water and you need to get it up into
• 8:22
  Speaker 1: the air on that hot day, and then you need
• 8:23
  Speaker 1: to cool it down. And the best way for that
• 8:26
  Speaker 1: to happen is for the night to be clear so
• 8:29
  Speaker 1: there's good cooling because otherwise some of that heat is
• 8:31
  Speaker 1: going to be reflected by the clouds back at the earth.
• 8:34
  Speaker 1: For there to be very light winds because winds tend
• 8:37
  Speaker 1: to mix up the hot and the cold air, and
• 8:40
  Speaker 1: for the ground to be as cold as possible. So
• 8:42
  Speaker 1: on a clear night with light wind and cool ground
• 8:46
  Speaker 1: after a rainy day or near a lake, you're very
• 8:49
  Speaker 1: likely to get fog.
• 8:51
  Speaker 2: Okay, awesome, Now let's give me why do I want
• 8:53
  Speaker 2: to know about salt.
• 8:54
  Speaker 1: Also, when I was reading about this, I was thinking
• 8:57
  Speaker 1: about air being saturated by water and imagining that maybe
• 9:02
  Speaker 1: it was similar to dissolving something into a solution. Like
• 9:06
  Speaker 1: you know how you can put salt into water and
• 9:08
  Speaker 1: then you don't see it right. It's not visible the
• 9:10
  Speaker 1: same way that there can be like water in the air,
• 9:12
  Speaker 1: but you're not looking at it right. It's like held
• 9:15
  Speaker 1: by the air, And so I imagined that it was similar.
• 9:18
  Speaker 1: Maybe this is the same kind of process. You can
• 9:20
  Speaker 1: use your intuition. It turns out it's not. Yeah, when
• 9:25
  Speaker 1: you dissolve salt into water, the salt actually forms bonds
• 9:28
  Speaker 1: with the water. It's like actually a chemical solution. But
• 9:31
  Speaker 1: water in the air is just more like a mixture
• 9:33
  Speaker 1: of gases. You have like a mixture of air and
• 9:35
  Speaker 1: water vapor. So it's not a great analogy. So for
• 9:38
  Speaker 1: those people listening and thinking you can use your intuition
• 9:40
  Speaker 1: for salt and water to understand air and water, that's
• 9:44
  Speaker 1: a bit of a trap. So don't go down that hole.
• 9:48
  Speaker 1: But there is something really fascinating happening here. Chemically, we
• 9:51
  Speaker 1: talked about the dew point, the temperature beyond which things
• 9:54
  Speaker 1: precipitate out into the air. It's not actually quite so simple.
• 9:58
  Speaker 1: What's really happening is you have condon at every temperature,
• 10:01
  Speaker 1: and you also have evaporation at every temperature. What happens
• 10:04
  Speaker 1: when you cross the duw point is that you have
• 10:06
  Speaker 1: more condensation than evaporation. So above the due point, you
• 10:10
  Speaker 1: have more evaporation than condensation, so the air is taking
• 10:13
  Speaker 1: in more water if you like, are injecting water somehow,
• 10:17
  Speaker 1: then the air is gobbling that up, whereas below the
• 10:19
  Speaker 1: due point you have more condensation than evaporation, so the
• 10:22
  Speaker 1: air is losing the water. So it's a smooth transition
• 10:26
  Speaker 1: as you cross the due point between being dominated by
• 10:28
  Speaker 1: condensation and being dominated by evaporation. And this helps you
• 10:33
  Speaker 1: understand why it's temperature dependent also because imagine the air
• 10:38
  Speaker 1: and you have all these molecules of air, and then
• 10:40
  Speaker 1: you also have water in the air, right, But there's
• 10:43
  Speaker 1: no bonds between the water and the air, but there
• 10:45
  Speaker 1: are bonds between the water molecules. So you have a
• 10:48
  Speaker 1: droplet of water in the air like a little in
• 10:51
  Speaker 1: one piece of fog, like a fog particle or a
• 10:54
  Speaker 1: foggino or whatever. Then it's held together by little bonds
• 10:59
  Speaker 1: because water is polar, remember, and so like one end
• 11:02
  Speaker 1: of it is charged positive, one end of his charge negative,
• 11:05
  Speaker 1: so it can kind of stick together. So water molecules
• 11:08
  Speaker 1: when it's a little drop of fog are bound together
• 11:11
  Speaker 1: by these hydrogen bonds between the molecules, and in order
• 11:14
  Speaker 1: to evaporate, they have to have enough energy, enough kinetic
• 11:18
  Speaker 1: energy to evaporate. So as the temperature goes up, more
• 11:21
  Speaker 1: of these things have enough kinetic energy to break those
• 11:23
  Speaker 1: bonds and evaporate into the air. So that's why at
• 11:26
  Speaker 1: higher temperatures there's more water that can bounce around without
• 11:30
  Speaker 1: getting stuck to other little water molecules and making little
• 11:33
  Speaker 1: fuggy know, particles. So it's all about the temperature of
• 11:36
  Speaker 1: the water really and force. The temperature of the air
• 11:39
  Speaker 1: and the water are the same because they're an equilibrium.
• 11:43
  Speaker 2: So what do you think it is about foggy mornings
• 11:45
  Speaker 2: that make zombies more likely to be moving around? You
• 11:52
  Speaker 2: look a little frustrated.
• 11:53
  Speaker 1: Actually, sorry, I pride myself in being able to prepare
• 11:59
  Speaker 1: for almost any question. You're going to ask, Wow, you
• 12:02
  Speaker 1: totally caught me slash footed. So here's a completely impromptu answer.
• 12:09
  Speaker 1: The Foggino particles interact with the zombie field, and so
• 12:12
  Speaker 1: there's a resonance between those two, and so sometimes the
• 12:15
  Speaker 1: zombie field will get energy from the Foggino particles and
• 12:19
  Speaker 1: then you'll just precipitate zombies out of the quantum vacuum.
• 12:22
  Speaker 2: Holy wow. Yeah, oh my gosh.
• 12:24
  Speaker 1: Also that was complete nonsense and so.
• 12:27
  Speaker 2: Obviously, but that was amazing. You used all the right
• 12:29
  Speaker 2: words in all of the fancy ways, and you know,
• 12:32
  Speaker 2: I think maybe we should start doing like a supernatural
• 12:35
  Speaker 2: sort of podcast, and then maybe we could get ahead
• 12:38
  Speaker 2: of Oh, what is the show that's ahead of us
• 12:42
  Speaker 2: watch Chronicles. Yeah.
• 12:46
  Speaker 1: No, that's just a lesson and how easy it is
• 12:48
  Speaker 1: to sound like you know what you're talking about if
• 12:50
  Speaker 1: you use big, fancy words, even if you're spewing gibberish.
• 12:53
  Speaker 2: Yes, all right, anyway, okay, so sorry, back to the
• 12:55
  Speaker 2: fogginos and okay, so so do in the morning fog
• 13:00
  Speaker 2: that has settled on plants and stuff exactly. Side note,
• 13:05
  Speaker 2: just to like Kelly being a nature nerd. One of
• 13:07
  Speaker 2: my favorite things in the morning is to walk through
• 13:10
  Speaker 2: our hayfields and see all of the teeny tiny little
• 13:12
  Speaker 2: spiderwebs that I always miss, but you can see them
• 13:15
  Speaker 2: because the dew has settled on them. There are literally
• 13:18
  Speaker 2: thousands of them out there. There's this tiny little universe
• 13:21
  Speaker 2: that you can only see in the morning when the
• 13:24
  Speaker 2: dew makes it visible and you miss it otherwise. And
• 13:27
  Speaker 2: it's just like when you look at the world at
• 13:29
  Speaker 2: different scales, there's all of these things that you missed
• 13:32
  Speaker 2: at the scale that you live. And anyway, I love
• 13:35
  Speaker 2: walking in the morning, like when you can still see
• 13:37
  Speaker 2: what the dew makes visible, and a good reason to
• 13:40
  Speaker 2: get up early.
• 13:40
  Speaker 1: Sometimes in high school I had to get up early
• 13:42
  Speaker 1: for marching band, and the field was always covered in
• 13:45
  Speaker 1: dew which is then frozen. Oh and crunching on those
• 13:48
  Speaker 1: frozen blades of grass that was always so satisfied.
• 13:51
  Speaker 2: Oh okay, I thought you were going to say you
• 13:52
  Speaker 2: didn't like that, So yes, two positive stories about getting
• 13:55
  Speaker 2: up early.
• 13:56
  Speaker 1: I did not like getting up early for marching band.
• 13:58
  Speaker 1: That was the one good thing about it. The first
• 14:00
  Speaker 1: in grass, you know, it's satisfying. The way like stepping
• 14:04
  Speaker 1: on a frozen river and cracking that ice is also satisfying.
• 14:07
  Speaker 1: I don't know if you feel that way.
• 14:08
  Speaker 2: Yeah, no, I like that. I like that. Can I
• 14:10
  Speaker 2: share one negative getting up early story? And then we
• 14:12
  Speaker 2: really need to get back? Should we just get back
• 14:14
  Speaker 2: on track? Maybe we should just get back on track?
• 14:17
  Speaker 1: Well, why don't you say it? And it's not funny enough?
• 14:19
  Speaker 2: Okay?
• 14:19
  Speaker 3: All right?
• 14:20
  Speaker 2: So when I was in high school, senior year of
• 14:22
  Speaker 2: high school, I worked at a bakery at a zoo,
• 14:25
  Speaker 2: and I had to get there at five am to
• 14:27
  Speaker 2: cook the cookies before everyone got there. And one morning
• 14:29
  Speaker 2: I was feeling super grumpy and I was like, I
• 14:31
  Speaker 2: can't who in high school gets a job where you
• 14:33
  Speaker 2: have to be there at five am? What am I thinking?
• 14:37
  Speaker 4: Right?
• 14:37
  Speaker 2: And so I get there and this little bird lands
• 14:40
  Speaker 2: on a fence and it starts singing this beautiful song,
• 14:42
  Speaker 2: and I'm like, okay, all right, this is why you
• 14:45
  Speaker 2: get here?
• 14:46
  Speaker 1: And was there fog?
• 14:47
  Speaker 2: I don't remember. I don't remember that.
• 14:49
  Speaker 1: I just remember telling there has to be fogg to
• 14:51
  Speaker 1: connect to the question, and.
• 14:52
  Speaker 2: There was fog, but no zombies and anyway, singing this
• 14:56
  Speaker 2: beautiful song, and then out of nowhere, a raptor comes
• 15:01
  Speaker 2: by and literally oops the bird up and rips its
• 15:06
  Speaker 2: neck out, and I was like, that's mornings for you. Yes,
• 15:12
  Speaker 2: that feels a little bit more on key, and anyway,
• 15:14
  Speaker 2: I felt so bad for that.
• 15:15
  Speaker 1: That's biology for that.
• 15:17
  Speaker 2: That's biology for you, and anyway that felt Yeah. I
• 15:20
  Speaker 2: was like, no, right, okay, that's right. This is why
• 15:22
  Speaker 2: you don't get up in the mornings early birds, I
• 15:25
  Speaker 2: don't know they get their next ripped out.
• 15:28
  Speaker 1: Be careful early birds because in the morning there's fog
• 15:30
  Speaker 1: and the raptors can swoop down out of their hiding
• 15:33
  Speaker 1: places in the mist. That's right, all right, So chance,
• 15:36
  Speaker 1: send this explanation to your six year old and let's
• 15:38
  Speaker 1: see if we've scratched that itch or confused them with
• 15:43
  Speaker 1: stories of raptors and zombies.
• 15:45
  Speaker 6: And kids so much. Nine questions. I think it's cool, Sponge.
• 15:53
  Speaker 6: I don't have any questions, thank you.
• 16:15
  Speaker 1: Okay, we're back and we're answering questions from listeners as
• 16:18
  Speaker 1: well as giving live updates on Kelly's goat.
• 16:21
  Speaker 2: Oh that's staying in the show.
• 16:23
  Speaker 1: Huh Kelly, did your goat give birth?
• 16:26
  Speaker 2: No? Not yet, not yet. She was chewing her cut
• 16:28
  Speaker 2: and she got up to say hi. When I went
• 16:30
  Speaker 2: out to check on her. So she is not in
• 16:32
  Speaker 2: active labor right now, but her utters are bigger, so.
• 16:36
  Speaker 1: I think we're are they utterly huge?
• 16:38
  Speaker 2: They're not utterly huge yet, but her bag has expanded,
• 16:43
  Speaker 2: as the vet said, So.
• 16:44
  Speaker 1: Well, I'm gonna milk these jokes as as I can.
• 16:46
  Speaker 2: Amazing, amazing, and I'm going to see how many zombie
• 16:49
  Speaker 2: references I can get in there, so we'll this is
• 16:52
  Speaker 2: gonna be a great show.
• 16:54
  Speaker 3: All right.
• 16:54
  Speaker 1: Well, the next question is not about goats or zombies
• 16:57
  Speaker 1: or even vampires, but it is about bat.
• 17:00
  Speaker 2: Ooh yes, so this is a question from Huntington. And
• 17:04
  Speaker 2: this is also a question that involves a child, which
• 17:07
  Speaker 2: I love, so yeah, and absolutely keep sending us questions
• 17:10
  Speaker 2: that you and your kids have, or just questions your
• 17:12
  Speaker 2: kids have, and so let's go ahead and hear the question.
• 17:15
  Speaker 4: Now, Hi, Daniel and Kelly, We're probably blame more. Kelly,
• 17:19
  Speaker 4: My son and I were reading about bats and the
• 17:21
  Speaker 4: book said that bats have valves in their circulatory system,
• 17:24
  Speaker 4: so the blood can't rush to their heads when they
• 17:26
  Speaker 4: are upside down and make them dizzy. Why Some then.
• 17:29
  Speaker 6: Asked why ol geckos get dizzy.
• 17:31
  Speaker 4: I'm wondered if gecko's had something similar in their bodies
• 17:34
  Speaker 4: to bats. I looked but couldn't find the answer and
• 17:36
  Speaker 4: was hoping you could help out.
• 17:38
  Speaker 1: Thank you boy, this is a great question. But before
• 17:40
  Speaker 1: we understand like bats and geckos getting dizzy, you like,
• 17:44
  Speaker 1: what does it mean to get dizzy? Anyway? Why do
• 17:46
  Speaker 1: humans get dizzy? What is that all about?
• 17:48
  Speaker 2: Yeah? Yeah, So when I get a question, one of
• 17:50
  Speaker 2: the first things that I do is I like break
• 17:53
  Speaker 2: the question into pieces, and then you have to check
• 17:55
  Speaker 2: the premise of each part of the question. You know,
• 17:58
  Speaker 2: not because you don't trust the list, but because, like
• 18:00
  Speaker 2: you know one, you just want to make sure that
• 18:02
  Speaker 2: everybody understands all the different parts of the question. So
• 18:05
  Speaker 2: the first part of the question here is why do
• 18:08
  Speaker 2: you get dizzy? And so what's implicit in this question
• 18:12
  Speaker 2: here is that what makes you dizzy is the blood
• 18:14
  Speaker 2: rushing to your head. And you know, maybe when the
• 18:17
  Speaker 2: blood rushes to your head, it can't get back to
• 18:19
  Speaker 2: your heart and so it doesn't get oxygenated, or maybe
• 18:21
  Speaker 2: it's the change and the fluid pressure in your head.
• 18:24
  Speaker 2: But actually getting dizzy is a very complicated thing and
• 18:28
  Speaker 2: it can be caused by a lot of different things.
• 18:30
  Speaker 2: So I was looking at like a MAO clinic website,
• 18:32
  Speaker 2: and anxiety can make you dizzy? Really, yeah, apparently. And
• 18:36
  Speaker 2: folks who study virtual reality and who try to make
• 18:39
  Speaker 2: those virtual reality headsets have been sort of amazed at
• 18:44
  Speaker 2: the many different ways that humans can become dizzy when you,
• 18:47
  Speaker 2: you know, put them in a virtual reality setup and
• 18:51
  Speaker 2: they'll report like, oh, no, that made me dizzy. Now
• 18:53
  Speaker 2: I kind of want to puke, you know. No, you're underwater.
• 18:56
  Speaker 2: Setup didn't calm me down. It made me feel like
• 18:58
  Speaker 2: the world is spinning. And so anyway, being dizzy is
• 19:01
  Speaker 2: a complicated thing. But let's look at two potential reasons
• 19:05
  Speaker 2: for getting dizzy. Let's go ahead and dig into the
• 19:08
  Speaker 2: one that's implied in the question first, which is blood
• 19:11
  Speaker 2: rushing to your head.
• 19:12
  Speaker 1: Blood rushing your head makes you dizzy. I always thought
• 19:14
  Speaker 1: it was low blood pressure that made you dizzy.
• 19:17
  Speaker 2: Yeah, So for me, when I stand up and you know,
• 19:19
  Speaker 2: I have less blood in my head for a moment,
• 19:22
  Speaker 2: that is what makes me dizzy. And I'll admit I
• 19:25
  Speaker 2: shared some of this question on Blue Sky. I did
• 19:28
  Speaker 2: get some responses from people being like, blood rushing to
• 19:31
  Speaker 2: my head doesn't get me dizzy. It's blood rushing out
• 19:33
  Speaker 2: of my head right, that makes me dizzy. And so
• 19:35
  Speaker 2: it did seem like there was a general agreement that
• 19:38
  Speaker 2: it's the getting up that makes you dizzy, not the
• 19:41
  Speaker 2: blood rushing to the head that makes you dizzy. But
• 19:44
  Speaker 2: there were folks trying to understand how maybe blood rushing
• 19:47
  Speaker 2: to the head could make you dizzy, and the general
• 19:49
  Speaker 2: consensus was that maybe what's happening is that when the
• 19:52
  Speaker 2: blood rushes to your head, you know, one you get
• 19:55
  Speaker 2: a pressure increase. Maybe that's a bit disorienting. But two,
• 19:58
  Speaker 2: maybe the blood is pool in your head, and when
• 20:01
  Speaker 2: it pools in your head, perhaps you get low oxygen
• 20:04
  Speaker 2: because your body is used to gravity helping you get
• 20:07
  Speaker 2: the blood down right, and so it's less good at
• 20:12
  Speaker 2: pumping the blood away from your head when your head
• 20:15
  Speaker 2: is in the wrong orientation, and so maybe it's not
• 20:18
  Speaker 2: oxygenating as well under these conditions. And so maybe under
• 20:21
  Speaker 2: these lower oxygen conditions and this higher pressure, it's making
• 20:26
  Speaker 2: you sort of dizzy. I see, And again I'm not
• 20:29
  Speaker 2: actually sure that that does cause dizziness. There was some
• 20:32
  Speaker 2: debate about that, but the statement that was made in
• 20:35
  Speaker 2: this book was that for bats this isn't a problem.
• 20:39
  Speaker 2: Even though they sleep upside down because their circulatory system
• 20:43
  Speaker 2: has valves, and these valves essentially keep the blood from
• 20:48
  Speaker 2: pooling in the head, and so I think the idea
• 20:51
  Speaker 2: here would be that they make it so the blood
• 20:53
  Speaker 2: can't flow in the wrong direction and pool. And so
• 20:57
  Speaker 2: that was the statement. And so the question was bats
• 21:00
  Speaker 2: have these valves? Do geckos have the valves too?
• 21:04
  Speaker 1: And I guess humans don't have these valves because humans
• 21:07
  Speaker 1: can't be upside down for very long with other their
• 21:08
  Speaker 1: heads popping or something.
• 21:09
  Speaker 2: Right, Well, okay, so the equivalent of being upside down
• 21:12
  Speaker 2: essentially would be like being in space. So when you
• 21:16
  Speaker 2: are in space, if it's something you know that's right, yes, yeah, right.
• 21:19
  Speaker 2: I was like, I don't know the answer to that,
• 21:20
  Speaker 2: but I know the answer is something else. So when
• 21:22
  Speaker 2: you're in space, the fluids shift up to your head
• 21:25
  Speaker 2: and people do report feeling, you know, dizzy and disoriented.
• 21:29
  Speaker 2: But that is partly maybe because of fluid shifts, but
• 21:32
  Speaker 2: also because of this other thing that we're going to
• 21:34
  Speaker 2: talk about in a moment, which is it messes up
• 21:37
  Speaker 2: your vestibular system. Also, you're what system vestibular system hold on.
• 21:41
  Speaker 2: That's the next thing we're going to talk about. Okay,
• 21:43
  Speaker 2: But what we do with our fluid shifts is we
• 21:47
  Speaker 2: pee a lot, and so our body releases a lot
• 21:51
  Speaker 2: of fluids because our body is like, there's too much
• 21:53
  Speaker 2: pressure up here. We're kind of confused about it, and
• 21:56
  Speaker 2: so you urinate a lot, you lose a lot of
• 21:59
  Speaker 2: the fluid. But we do think that you still have
• 22:01
  Speaker 2: problems resulting from having too much fluid in your head. So,
• 22:04
  Speaker 2: for example, astronaut vision gets worse over time, and we
• 22:07
  Speaker 2: think partly that's because you do have more pressure in
• 22:10
  Speaker 2: your head because of more fluids in your head, and
• 22:13
  Speaker 2: we think that's pressing on your eyeballs. And people also
• 22:16
  Speaker 2: report that there are wrinkles go away because with more
• 22:19
  Speaker 2: fluid in their faces, it kind of presses out the
• 22:22
  Speaker 2: wrinkles in their skin and so but they survive. So anyway,
• 22:26
  Speaker 2: I think you can essentially have fluids pushing up on
• 22:29
  Speaker 2: your head and survive. Your body has ways of dealing
• 22:31
  Speaker 2: with it. They're kind of weird though.
• 22:33
  Speaker 1: But bats have these special valves. And now we're on
• 22:35
  Speaker 1: to geckos.
• 22:36
  Speaker 2: Okay, but no, or do they?
• 22:38
  Speaker 3: Oh?
• 22:38
  Speaker 1: I see.
• 22:39
  Speaker 2: So the first thing I do is I was like,
• 22:40
  Speaker 2: all right, well, I'm gonna look it up. Do bets
• 22:42
  Speaker 2: have these valves? And so I did find some websites
• 22:46
  Speaker 2: like when I just did a plain Google search that
• 22:48
  Speaker 2: we're saying like, oh, bats have these valves, blah blah blah.
• 22:51
  Speaker 2: I was all right, well, I'm gonna find a scientific
• 22:52
  Speaker 2: paper that talks about these valves. And I found mention
• 22:55
  Speaker 2: of valves in the wings that like help them with flying,
• 22:59
  Speaker 2: but I couldn't find mention of any valves related to
• 23:02
  Speaker 2: helping them deal with being upside down. And in fact,
• 23:06
  Speaker 2: I even found a paper that talked about how bats
• 23:08
  Speaker 2: sleep upside down, and they were talking about how when
• 23:12
  Speaker 2: they sleep upside down, there's an increase in their cranial
• 23:16
  Speaker 2: pressure because fluids shift into their brain, which would suggest, yeah,
• 23:20
  Speaker 2: they don't have these valves. And in fact, that paper
• 23:23
  Speaker 2: did not talk about valves at all, And in fact,
• 23:24
  Speaker 2: they talked about how if you hold bats upside down
• 23:26
  Speaker 2: for even longer, their heart remodels to deal with the
• 23:31
  Speaker 2: fact that, wow, it needs to accommodate being upside down.
• 23:35
  Speaker 1: But why can it be such a deep mystery whether
• 23:37
  Speaker 1: or not bats have these valves. Bats are not like
• 23:40
  Speaker 1: rare or microscopic or invisible or shifting into zombies in
• 23:45
  Speaker 1: the morning mist Like, why doesn't somebody just open up
• 23:47
  Speaker 1: a bat carcass and look?
• 23:49
  Speaker 2: Okay, Well, so here's the thing. Another valve story that
• 23:53
  Speaker 2: I've heard a lot, and I'm going to answer your question,
• 23:56
  Speaker 2: just stick with me for a second, is that giraffes
• 23:59
  Speaker 2: have these valves also because they have these very long necks, right, yeah,
• 24:03
  Speaker 2: and then when their head goes down to take a
• 24:05
  Speaker 2: drink of water, they also need to have valves to
• 24:07
  Speaker 2: make sure that their blood isn't rushing to their head
• 24:09
  Speaker 2: and then rushing back. Right.
• 24:11
  Speaker 1: I'm imagining some like complicated steampunk giraffe now energetically pumping
• 24:15
  Speaker 1: stuff up and then pumping it back when the head
• 24:17
  Speaker 1: turns around. This is a crazy system.
• 24:19
  Speaker 2: Well, so the idea is that they've got these valves
• 24:21
  Speaker 2: so that the blood like is essentially stopped from like
• 24:24
  Speaker 2: pooling in the wrong spots. And so there was an
• 24:26
  Speaker 2: experiment that had these giraffes that they anestatized and they
• 24:30
  Speaker 2: held them up in the air in these braces, and
• 24:33
  Speaker 2: then they essentially while they were anestatized, lifted their heads
• 24:36
  Speaker 2: up and then put their heads down and then kept
• 24:39
  Speaker 2: track of like where things were going.
• 24:40
  Speaker 1: So they're like, they're like tilting these snoozing giraffes. What
• 24:44
  Speaker 1: a hilarious experiment.
• 24:46
  Speaker 2: Oh my gosh, I know, amazing, Right, And so then
• 24:47
  Speaker 2: they were like monitoring changes in pressure and then like
• 24:50
  Speaker 2: looking at like how the hearts were responding and stuff
• 24:53
  Speaker 2: like that. And they then they looked and that like
• 24:56
  Speaker 2: you know, where are the valves and stuff? And here
• 24:58
  Speaker 2: it says his biological examinations revealed no valves in the
• 25:03
  Speaker 2: carotid arteries, although such arterial vowels have been mentioned in
• 25:07
  Speaker 2: more popular accounts such as the Encyclopedia Britannica online.
• 25:12
  Speaker 1: Oh no, wow, you're calling out the Encyclopedia Britannica here, Kelly.
• 25:17
  Speaker 2: I am not the paper is the paper is. And
• 25:19
  Speaker 2: so I think that there has been like this vowelves
• 25:24
  Speaker 2: deal with being upside down idea that has maybe escaped
• 25:28
  Speaker 2: into the popular imagination.
• 25:31
  Speaker 1: Another example of a gap between scientific and popular.
• 25:34
  Speaker 2: Knowledge, maybe, And I'd love to know where this came from.
• 25:37
  Speaker 2: And so anyway, so okay, basically what I'm saying is
• 25:39
  Speaker 2: I watched a bunch of videos and the bat experts,
• 25:42
  Speaker 2: when you ask them how bats managed to be upside down,
• 25:44
  Speaker 2: they did not mention the valves. What they said was
• 25:48
  Speaker 2: bats are so small it doesn't matter. Oh, they have
• 25:53
  Speaker 2: strong hearts, and the distance between their heart and their
• 25:56
  Speaker 2: head is small enough that they can just pump it
• 26:00
  Speaker 2: and it's okay. Their hearts just get stronger if they
• 26:03
  Speaker 2: need to. And they didn't say anything about valves. They
• 26:06
  Speaker 2: just said they're small enough, doesn't matter. And I couldn't
• 26:09
  Speaker 2: find any evidence of valves.
• 26:10
  Speaker 1: This is a fascinating crossover between physics and biology. Actually,
• 26:14
  Speaker 1: it's not like you can take the same biological system
• 26:16
  Speaker 1: and just like scale it up by a thousand or
• 26:18
  Speaker 1: scale it down by a thousand and assume it's going
• 26:20
  Speaker 1: to operate the same way, because like pressure and volume
• 26:23
  Speaker 1: and surface area and mass, these things all grow differently
• 26:27
  Speaker 1: with size, and so they'll be like totally out of
• 26:29
  Speaker 1: whack if it gets too big or too small. So
• 26:32
  Speaker 1: you're saying the same system, which is susceptible to getting
• 26:34
  Speaker 1: dizzy and having blood pooling at our scale or maybe
• 26:37
  Speaker 1: even giraffes, doesn't happen for bats.
• 26:39
  Speaker 2: I think that is the answer, because like the bat experts,
• 26:44
  Speaker 2: we're not mentioning the valves. I couldn't find the valves
• 26:46
  Speaker 2: in the literature. If anybody wants to write into correct me,
• 26:49
  Speaker 2: please tell me. And then in a future Listener Questions episode,
• 26:52
  Speaker 2: at the beginning of the episode, I will say, there
• 26:54
  Speaker 2: is evidence of the valves and I just missed it.
• 26:57
  Speaker 1: Send us proof of the alleged bat valves.
• 27:00
  Speaker 2: Well, I mc daniel and I would always like to
• 27:01
  Speaker 2: be corrected if we're wrong about something, So please let
• 27:04
  Speaker 2: us know.
• 27:05
  Speaker 1: Don't be shy right in with your well, actually comment.
• 27:07
  Speaker 2: Please you please, absolutely, okay. And so another reason that
• 27:11
  Speaker 2: we get dizzy is because we have this system in
• 27:14
  Speaker 2: our head that helps us figure out like balance and
• 27:18
  Speaker 2: where we are in the universe in this system. So
• 27:20
  Speaker 2: I use the word earlier, and I will, for Daniel's sake,
• 27:24
  Speaker 2: avoid biology jargon from here on out after I say
• 27:26
  Speaker 2: the word one more time.
• 27:28
  Speaker 1: Is this vestibular?
• 27:29
  Speaker 2: Vestibular? It's in your inner ear and it's a system
• 27:33
  Speaker 2: of tubes filled with fluid, and when you move, like
• 27:38
  Speaker 2: when you rotate your head side to side, the fluid
• 27:42
  Speaker 2: starts going around the tube.
• 27:44
  Speaker 1: It's an accelerometer.
• 27:45
  Speaker 2: It is, Yeah, it's like an accelerometer.
• 27:47
  Speaker 1: It is an accelerometer.
• 27:48
  Speaker 2: It is an accelerometer, and your brain detects that the
• 27:52
  Speaker 2: fluid is going around in that tube, and sometimes so
• 27:55
  Speaker 2: like if you start spinning in place over and over
• 27:59
  Speaker 2: and over again, the fluid in that tube is going
• 28:01
  Speaker 2: to start spinnings and spinning and spinning and spinning. And
• 28:03
  Speaker 2: then if you stop spinning all of a sudden, it's
• 28:05
  Speaker 2: going to take a little while for that fluid to
• 28:07
  Speaker 2: stop spinning. And so for a little while there, your
• 28:09
  Speaker 2: brain still gets the message that you are spinning, while
• 28:13
  Speaker 2: your eyes are telling your brain, I am not spinning.
• 28:16
  Speaker 2: And we think that that disconnect between what your ear
• 28:19
  Speaker 2: is telling your brain and what your eyes are telling
• 28:21
  Speaker 2: your brain is part of why you feel dizzy, because
• 28:23
  Speaker 2: you're getting conflicting information. And to be honest, we don't
• 28:26
  Speaker 2: one hundred percent understand dizziness.
• 28:28
  Speaker 1: Has nobody done the experiment of taking a bunch of
• 28:31
  Speaker 1: giraffes and putting them on a merry go around and
• 28:32
  Speaker 1: then you don't even remember about whether they got dizzy.
• 28:34
  Speaker 1: That seems like that would settle the question.
• 28:40
  Speaker 2: Yeah, we need a lot of money for that experiment.
• 28:42
  Speaker 2: Probably call us that's right, that's right, we will take
• 28:47
  Speaker 2: your money. But it does suggest actually that if you
• 28:50
  Speaker 2: spin in the opposite direction, that could slow the fluid down,
• 28:53
  Speaker 2: and that might be a way to help your dizziness
• 28:56
  Speaker 2: go away faster, which is kind of a fun experiment.
• 29:00
  Speaker 1: Medical advice people, not medical advice.
• 29:02
  Speaker 2: Kelly is never giving official medical advice. I am not
• 29:05
  Speaker 2: that kind of doctor.
• 29:06
  Speaker 1: If your kid is dizzy, do not spin them the
• 29:08
  Speaker 1: other way on our No, it's just an interesting thought experience.
• 29:11
  Speaker 2: That's right, that's right. And so we've got tubes that
• 29:14
  Speaker 2: go in multiple different directions to accommodate for spinning in
• 29:17
  Speaker 2: multiple different directions. And then we also have a system
• 29:21
  Speaker 2: of essentially crystals that are tied to hairs, and this
• 29:25
  Speaker 2: tells you about moving it like forward and backwards. And
• 29:29
  Speaker 2: so if you go forward really quick, then those crystals
• 29:33
  Speaker 2: are gonna get pushed forward and they'll pull on the hairs.
• 29:36
  Speaker 2: And that's how your body knows that, like, oh, we
• 29:38
  Speaker 2: just kind of moved forward, and that sends a message
• 29:40
  Speaker 2: to your brain that we move forward.
• 29:41
  Speaker 1: No, we accelerated, Kelly, we accelerate.
• 29:43
  Speaker 2: We accelerate, thank you, thank you.
• 29:45
  Speaker 1: Your ear can tell that you're moving or that heads
• 29:47
  Speaker 1: velocity can only measure acceleration. It's like a bowling ball
• 29:51
  Speaker 1: in the back of a truck, right it's seventy miles
• 29:53
  Speaker 1: an hour in the highway. The bowling ball doesn't move,
• 29:55
  Speaker 1: but if you hit the brakes, then the bowling ball
• 29:57
  Speaker 1: rolls to the front. So even if you didn't know
• 29:59
  Speaker 1: you're a lo and you couldn't measure your acceleration in
• 30:02
  Speaker 1: any other way, if you watch the ball, you can
• 30:04
  Speaker 1: tell if you're accelerating in any direction. And that's what's
• 30:07
  Speaker 1: happening in your ear. It's an accelerometer.
• 30:09
  Speaker 2: Okay, yes, So we've got two different kinds of accelerometers
• 30:13
  Speaker 2: in our ears, and geckos and bats have these as well.
• 30:18
  Speaker 2: Presumably geckos and bats could get dizzy also if they
• 30:23
  Speaker 2: moved too quickly and messed with these kinds of accelerometers.
• 30:27
  Speaker 2: And so I'm guessing they have the same kinds of constraints,
• 30:29
  Speaker 2: because I did look up do geckos, for example, also
• 30:34
  Speaker 2: have semicircular ducks, and they do also have these kinds
• 30:38
  Speaker 2: of semicircular canals, and so you know, I think they
• 30:41
  Speaker 2: could possibly also get dizzy. They've got the same system
• 30:43
  Speaker 2: that we have.
• 30:44
  Speaker 1: I think I might have a special mutation because I
• 30:46
  Speaker 1: tend to get dizzy when I hear too many biological
• 30:49
  Speaker 1: Latin names.
• 30:50
  Speaker 2: You know, I wanted to talk to you about that
• 30:52
  Speaker 2: because you told me that you wanted me to say
• 30:54
  Speaker 2: things like beetle one and beetle two, And I was
• 30:57
  Speaker 2: thinking that from now on, we're not saying muons, gluons,
• 31:02
  Speaker 2: no fermions, no bosons. It's particle one, particle two.
• 31:07
  Speaker 3: Uh.
• 31:07
  Speaker 2: And what's that's right? Yeah, we're gonna we're gonna simplify
• 31:11
  Speaker 2: all of this from from now on. Okay, So anyway
• 31:14
  Speaker 2: to finally answer the question, why don't geckos get dizzy?
• 31:18
  Speaker 1: Yeah, Uh, nobody knows, that's right.
• 31:21
  Speaker 2: Who knows. I think they might get dizzy. They I
• 31:24
  Speaker 2: think they have a similar semi circular canal system that
• 31:27
  Speaker 2: we have, and sometimes we get dizzy. Sloths hang upside down.
• 31:31
  Speaker 2: And I think the answer for why they don't get
• 31:33
  Speaker 2: dizzy is they move kind of slowly. That's an answer
• 31:36
  Speaker 2: I found online. So maybe geckos also have to be
• 31:38
  Speaker 2: a little careful about moving slowly sometimes. But if they're
• 31:41
  Speaker 2: running away from a predator, maybe they do get a
• 31:43
  Speaker 2: little bit dizzy from time to time, but they just
• 31:44
  Speaker 2: have to deal with it like the rest of us.
• 31:46
  Speaker 2: I don't know about this valve thing. I didn't find
• 31:49
  Speaker 2: evidence for it. But I'm welcoming people to correct me.
• 31:52
  Speaker 2: And thanks for this fun question. I enjoyed reading about
• 31:55
  Speaker 2: semi circular canals and the circulatory systems of bats and geckos,
• 32:00
  Speaker 2: and this took me down so many different rabbit holes, fascinating.
• 32:03
  Speaker 2: It was a lot of fun.
• 32:04
  Speaker 1: That's one of my favorite things about listener questions is
• 32:06
  Speaker 1: how can we learn in digging up the answers?
• 32:09
  Speaker 2: Absolutely all right, let's see if I gave a moderately
• 32:13
  Speaker 2: satisfactory answer to Huntington and your son. Let's see how
• 32:18
  Speaker 2: this went.
• 32:18
  Speaker 4: So what do you think?
• 32:20
  Speaker 6: That's pretty good? That's pretty good.
• 32:23
  Speaker 4: It's pretty good.
• 32:24
  Speaker 6: I'm wanted to I mean, I can't good. Okay, this
• 32:28
  Speaker 6: is googgs leazing. I need to catch Thank.
• 32:31
  Speaker 5: You for breaking down the question and exposing the assumptions
• 32:34
  Speaker 5: we didn't even know we were making. I'm honestly surprised
• 32:37
  Speaker 5: to learn that bats and giraffes don't have valves like
• 32:39
  Speaker 5: we had read about. I guess that is a lesson
• 32:42
  Speaker 5: about trusting and verifying the information we read in popsie books.
• 32:47
  Speaker 5: I guess I shouldn't have been surprised to learn that
• 32:50
  Speaker 5: for something we've all experienced. There is not a clear
• 32:52
  Speaker 5: explanation for dizziness, but I still was. My son enjoyed
• 32:56
  Speaker 5: the answers and was very satisfied with them, something that
• 33:01
  Speaker 5: I have never been able to provide with my answers.
• 33:04
  Speaker 5: So thanks again and keep up the great work.
• 33:31
  Speaker 2: All right, Worshock almost got out of the barn. Lottie's
• 33:33
  Speaker 2: looking a bit uncomfortable. I'm gonna be sitting with her
• 33:35
  Speaker 2: for the hour after we're done. But all right, we're
• 33:39
  Speaker 2: back to Daniel and Kelly's extraordinary universe and the extraordinarily
• 33:43
  Speaker 2: fun watching of goats kidding.
• 33:49
  Speaker 1: In the brief interval before Kelly's Good gives birth, we're
• 33:52
  Speaker 1: gonna try to answer a complicated question about what's going
• 33:55
  Speaker 1: on inside spinning black holes. Here's a fun question I
• 33:59
  Speaker 1: got from Joe.
• 34:01
  Speaker 3: Hi, Daniel and Kelly. This question is more for Daniel.
• 34:06
  Speaker 3: I understand that the inner workings of a black hole
• 34:09
  Speaker 3: are a mystery to us, But I heard something about
• 34:14
  Speaker 3: a couchy manifold. It's some kind of inner horizon, and
• 34:19
  Speaker 3: I'm wondering how these complex mathematics might be explained.
• 34:25
  Speaker 2: Oh, this is fun. I don't think I know what
• 34:26
  Speaker 2: a couchy manifold is did I say it right?
• 34:31
  Speaker 1: Koushi? Yeah?
• 34:32
  Speaker 2: Caushi? Well no are The answer is no because that's
• 34:35
  Speaker 2: not what I said. But you're nice.
• 34:39
  Speaker 6: I like that.
• 34:40
  Speaker 1: We can call it kouchy if you prefer to. Imagine
• 34:42
  Speaker 1: like sitting on a couch while understanding these things.
• 34:45
  Speaker 2: Oh yeah, I like sitting on a couch while understanding
• 34:47
  Speaker 2: the universe. So what is a cat Oh no, I
• 34:52
  Speaker 2: already forgot Koushi caushe So.
• 34:55
  Speaker 1: A cauchy horizon is where causality breaks down. And this
• 35:00
  Speaker 1: is going to be really surprising because we're talking about
• 35:03
  Speaker 1: classical physics, which is famous for being deterministic, which means that,
• 35:08
  Speaker 1: like the past determines the future. You have a bunch
• 35:10
  Speaker 1: of billiard balls, you shoot them at each other, they
• 35:13
  Speaker 1: bounce off at some angle. They're going to do that
• 35:15
  Speaker 1: every time. Because the past determines the future. There's no fuzziness,
• 35:19
  Speaker 1: there's no randomness. We're ignoring quantum mechanics completely for this answer.
• 35:24
  Speaker 1: Imagine we live in a universe ruled by classical physics.
• 35:27
  Speaker 1: Usually we think, and we talked about this on the
• 35:29
  Speaker 1: Weather Modeling episode. If you know everything about the universe,
• 35:33
  Speaker 1: like where all the particles are where they're going their
• 35:37
  Speaker 1: exact stated universe. Plus you know the rules of the universe,
• 35:42
  Speaker 1: meaning like how things interact and how they will bounce
• 35:45
  Speaker 1: off of each other, then you can predict the future. Right,
• 35:49
  Speaker 1: So perfect knowledge of the current state plus perfect knowledge
• 35:53
  Speaker 1: of the rules, you should be able to predict the future.
• 35:56
  Speaker 1: That's causality in a nutshell.
• 35:59
  Speaker 2: Sure, but I thought we also determined that it was
• 36:03
  Speaker 2: also a little too complicated and we couldn't actually predict
• 36:06
  Speaker 2: the future. But technically we should be able to if
• 36:09
  Speaker 2: we could do those complicated equations.
• 36:12
  Speaker 1: Yeah, okay, absolutely, if you had perfect knowledge of the universe,
• 36:16
  Speaker 1: which you never do, not even because of quantum mechanics,
• 36:19
  Speaker 1: but because there's just too much information. Like in the
• 36:22
  Speaker 1: case of the weather, we don't have enough booies out
• 36:25
  Speaker 1: in the ocean, and we don't have enough airplanes with
• 36:27
  Speaker 1: thermometers on them. We don't have all that information. But
• 36:30
  Speaker 1: in principle, that's a practical problem and engineers could overcome it.
• 36:34
  Speaker 1: The information exists and is accessible in a classical universe,
• 36:39
  Speaker 1: which isn't our universe. So there's lots of reasons why
• 36:42
  Speaker 1: this could never happen. But if you imagine a classical universe.
• 36:45
  Speaker 1: It is possible in principle to have that information. It
• 36:48
  Speaker 1: exists and in that classical universe, because we've assumed the
• 36:52
  Speaker 1: universe is classical and that there are rules, and if
• 36:54
  Speaker 1: we knew those rules, then in principle, we could perfectly
• 36:57
  Speaker 1: predict the future.
• 36:58
  Speaker 2: Got it.
• 36:58
  Speaker 1: Okay, that's the same, But there are some caveats, right,
• 37:02
  Speaker 1: and those caveats are what we're talking about today. Cave
• 37:04
  Speaker 1: At number one is about the speed of light, and
• 37:07
  Speaker 1: it's not actually directly related to the country horizon, but
• 37:10
  Speaker 1: it's a good warm up because what you actually need
• 37:13
  Speaker 1: to bridge the future is not all the knowledge in
• 37:16
  Speaker 1: the universe about what's happening. Some things in the universe
• 37:19
  Speaker 1: can't affect your immediate future. The only thing that can
• 37:23
  Speaker 1: affect the immediate future is parts of the universe where
• 37:26
  Speaker 1: light has had time to get here since that event. So,
• 37:30
  Speaker 1: for example, if there's an alien right now in Alpha
• 37:33
  Speaker 1: Centauri and they're aiming a death ray at us, and
• 37:37
  Speaker 1: they fire the button boom right now to shoot that
• 37:40
  Speaker 1: death ray at us, it cannot affect what's going to
• 37:42
  Speaker 1: happen right here on Earth in the next millisecond, because
• 37:46
  Speaker 1: there isn't time for that death ray to get here.
• 37:49
  Speaker 1: So we say in physics, it's not part of our
• 37:51
  Speaker 1: past light cone. Our past light cone is everything that
• 37:55
  Speaker 1: can affect the immediate future. And because there's a speed
• 37:59
  Speaker 1: limit on infrom and signaling, then things that can't get
• 38:03
  Speaker 1: here are outside of that past like cone.
• 38:05
  Speaker 2: Okay, I understand. It still feels like there's an approximately
• 38:09
  Speaker 2: infinite number of things we can't measure, and we've knocked
• 38:13
  Speaker 2: a small fraction of them out. But but but okay,
• 38:15
  Speaker 2: but all right, there's some things now we don't have
• 38:17
  Speaker 2: to worry about.
• 38:18
  Speaker 1: But of course that death ray will eventually arrive at Earth,
• 38:21
  Speaker 1: and in a couple of million years, that alien shooting
• 38:25
  Speaker 1: that deathray, that event will be in the past like
• 38:28
  Speaker 1: cone of our future. Right, So it's a time dependent thing.
• 38:32
  Speaker 1: Our past like cone, is not just a location. It's
• 38:35
  Speaker 1: locations and times. It's events in space time. Some of
• 38:39
  Speaker 1: those things that are outside our past like cone right
• 38:41
  Speaker 1: now can be in the past like cone of people
• 38:44
  Speaker 1: in our future. Right because aliens, if they shoot that
• 38:47
  Speaker 1: death ray, can kill our great great great great great
• 38:50
  Speaker 1: great great great grandchildren.
• 38:52
  Speaker 2: Okay, got it? So wait, what is the question that
• 38:53
  Speaker 2: we're trying to answer, then are we trying to answer
• 38:56
  Speaker 2: who's going to die? Because then it seems very relevant
• 38:58
  Speaker 2: to them.
• 38:59
  Speaker 1: So we're trying to answer what is a Cauchhi horizon?
• 39:02
  Speaker 1: And a Cauchhi horizon is a place where you cannot
• 39:05
  Speaker 1: predict the future? Okay, all right, And they might wonder
• 39:09
  Speaker 1: how does that happen? What's going on? Classical physics, things
• 39:12
  Speaker 1: are deterministic. In fact, they only depend on a subset
• 39:15
  Speaker 1: of the universe, your past light cone. How is it
• 39:18
  Speaker 1: possible to have in classical physics a setup where you
• 39:22
  Speaker 1: can't predict the future. And the answer is if you
• 39:26
  Speaker 1: have something in your past light cone like a singularity,
• 39:29
  Speaker 1: which is like a breakdown of classical physics, something that's unpredictable.
• 39:33
  Speaker 2: Okay.
• 39:34
  Speaker 1: The short answer is that a Caushi horizon is what
• 39:37
  Speaker 1: happens inside a spinning black hole where there's a singularity
• 39:41
  Speaker 1: inside your past light cone. And a singularity is not
• 39:44
  Speaker 1: something you can fold into your equations because it has
• 39:47
  Speaker 1: an infinity in it, and so it makes it impossible
• 39:49
  Speaker 1: to predict the future. Okay, So let's dig into that
• 39:52
  Speaker 1: a little bit more and understand why that happens. And
• 39:55
  Speaker 1: to do that, let's remember what a black hole is anyway.
• 39:59
  Speaker 1: A black hole in popular science is often like a
• 40:02
  Speaker 1: thing in space that has really strong gravity and sucks
• 40:05
  Speaker 1: everything up right. But actually gravity is not a force,
• 40:08
  Speaker 1: it's curvature of space. Time objects are moving to follow
• 40:12
  Speaker 1: that curvature, and black holes are just places with really
• 40:16
  Speaker 1: really strong curvature because you have a lot of mass
• 40:18
  Speaker 1: and a small area, so the curvature gets really really strong,
• 40:22
  Speaker 1: and it gets so strong that you get an event horizon.
• 40:25
  Speaker 1: Event horizon is like a dotted line in space, and
• 40:28
  Speaker 1: anything that goes inside the event horizon will never leave
• 40:32
  Speaker 1: the event horizon. Okay. So that means that a particle
• 40:35
  Speaker 1: inside the event horizon, its entire future is in the
• 40:39
  Speaker 1: event horizon. There's no place in the event horizon and
• 40:42
  Speaker 1: no particle trajectory you could even come up with that's
• 40:45
  Speaker 1: ever going to leave the event horizon, okay. And the
• 40:48
  Speaker 1: reason is fascinating because the curvature inside the black hole
• 40:51
  Speaker 1: is so strong that the singularity inside of the black
• 40:55
  Speaker 1: hole is not like a location in space. Space and
• 40:59
  Speaker 1: time get twisted so that singularity is a location in time.
• 41:03
  Speaker 1: You can think of it like inside the black hole,
• 41:05
  Speaker 1: space is one directional, so the singularity is always in
• 41:10
  Speaker 1: your future. No matter what you do, every path leads
• 41:14
  Speaker 1: to the singularity. So the singularity is not like a
• 41:17
  Speaker 1: place in space you can like fly by and try
• 41:19
  Speaker 1: to avoid. It's not like the grocery store. You can
• 41:23
  Speaker 1: go to it or you cannot go to it. It's
• 41:25
  Speaker 1: like next Tuesday. There's nothing you can do to avoid
• 41:28
  Speaker 1: Next Tuesday. It's coming. You can't pass it, you can't
• 41:31
  Speaker 1: go around it. It's in your future.
• 41:34
  Speaker 2: Okay. So before we were talking about being in a
• 41:37
  Speaker 2: light cone where aliens were going to destroy us, Yeah,
• 41:42
  Speaker 2: and there could be a singularity, and now we're talking
• 41:46
  Speaker 2: about singularities in a black hole.
• 41:48
  Speaker 1: Yeah, and so the connection is so remember we're answering
• 41:51
  Speaker 1: the question what is a Cowshie horizon. Cawshi horizon is
• 41:55
  Speaker 1: a place in space where predictions break down, and they
• 41:59
  Speaker 1: break down because you have a singularity in your past
• 42:01
  Speaker 1: like cone, it's like in your history. And singularities are infinities.
• 42:05
  Speaker 1: You can't use them to calculate. And it's a special
• 42:08
  Speaker 1: kind of singularity because the normal kind of singularity we're
• 42:11
  Speaker 1: talking about, the kind that are inside vanilla black holes,
• 42:14
  Speaker 1: are not like that. They're in your future. A singularity
• 42:18
  Speaker 1: inside a vanilla black hole can never be in your
• 42:21
  Speaker 1: past like cone. It's always in your future, right, It
• 42:24
  Speaker 1: can't affect anything that's happening. It's always something that's going
• 42:28
  Speaker 1: to happen to you. So how do you get a
• 42:31
  Speaker 1: singularity in your past like cone so you can disrupt
• 42:34
  Speaker 1: your predictions of the future. For that, you need a
• 42:37
  Speaker 1: special kind of black hole. You need a rotating black hole.
• 42:41
  Speaker 1: Black holes we've been talking about so far just a
• 42:43
  Speaker 1: dense point in space. Curvature is really really strong. Space
• 42:48
  Speaker 1: is bent so that the singularity is in your future.
• 42:51
  Speaker 1: But if you spin that black hole, you get a
• 42:53
  Speaker 1: very different kind of space time structure. Something that happens
• 42:57
  Speaker 1: in Einstein's gravity, which differentiates it from Newton's gravity. Newton
• 43:01
  Speaker 1: says gravity's a force. Einstein says it's a curvature. Most
• 43:05
  Speaker 1: of the time they give the same answers, but they
• 43:07
  Speaker 1: differ when the mass is spinning. Newton says something that's
• 43:12
  Speaker 1: spinning has the same force as something that's not spinning.
• 43:14
  Speaker 1: It doesn't make any difference, like the force on the
• 43:17
  Speaker 1: Moon from the Earth doesn't depend on the fact that
• 43:19
  Speaker 1: the Earth is spinning. According to Newton, Einstein says, actually,
• 43:23
  Speaker 1: gravity is curvature in response to energy. Spinning is a
• 43:26
  Speaker 1: kind of energy, And he's got all these complicated equations.
• 43:30
  Speaker 1: It's like sixteen of them in a big tensor. So
• 43:33
  Speaker 1: the direction matters, and it causes a twist in space
• 43:36
  Speaker 1: time itself. So it's a very complicated response to spinning.
• 43:40
  Speaker 1: And so what it means is that inside a spinning
• 43:43
  Speaker 1: black hole there's two horizons. There's still the event horizon,
• 43:47
  Speaker 1: just like a normal black hole. Once you fall in
• 43:49
  Speaker 1: the event horizon, there's an inner horizon that's the Cauchy horizon.
• 43:54
  Speaker 1: The Cauhi horizon is still in your future. So you
• 43:56
  Speaker 1: fall into the spinning black hole, then there's no way
• 43:59
  Speaker 1: to avoid falling in even further till you get past
• 44:01
  Speaker 1: the Kaushi horizon. Once you're inside the Caushi horizon, then
• 44:06
  Speaker 1: the spinning singularity at its heart is not in your future.
• 44:10
  Speaker 1: It's a different kind of singularity. It's actually avoidable. You
• 44:14
  Speaker 1: can like be in an orbit around that singularity. It's
• 44:17
  Speaker 1: not just in your future. It's more like the grocery
• 44:20
  Speaker 1: store than like next Tuesday. The problem is that that
• 44:25
  Speaker 1: means it can be in your past. It can affect
• 44:27
  Speaker 1: things that happen to You can like send out signals
• 44:30
  Speaker 1: from the singularity which can arrive at you and change
• 44:33
  Speaker 1: what happens to you. But nobody knows how to calculate
• 44:36
  Speaker 1: what signals what a singularity send out. It's an infinity,
• 44:38
  Speaker 1: it's a breakdown. So inside the Cashi horizon, you have
• 44:42
  Speaker 1: this thing which can be in your past, but it's
• 44:44
  Speaker 1: also sort of nonsense, like you don't know how to
• 44:47
  Speaker 1: calculate it, and because of that, it means you can't
• 44:50
  Speaker 1: predict what's going to happen. So you have a situation
• 44:53
  Speaker 1: in the universe where you have something in your past
• 44:56
  Speaker 1: like cone which can affect your future. We're not talking
• 44:59
  Speaker 1: about faster than like communication. But also you don't know
• 45:02
  Speaker 1: how to calculate it, so you can't predict your future.
• 45:05
  Speaker 1: It's like you were saying before, if you don't have
• 45:07
  Speaker 1: all the initial information, if you can't describe the current
• 45:10
  Speaker 1: state of events, you can't predict the future. Well, what
• 45:12
  Speaker 1: if there's something that's just indescribable in your current state
• 45:16
  Speaker 1: of events, then you can't predict the future. So the
• 45:18
  Speaker 1: Caushi horizon is the part of space time inside a
• 45:21
  Speaker 1: spinning black hole where you have this singularity in your past,
• 45:26
  Speaker 1: and so predictions are just off, like you just cannot
• 45:29
  Speaker 1: make them. It's amazing because you think of classical physics
• 45:32
  Speaker 1: as predictable, deterministic, like a clockwork universe, But there are
• 45:37
  Speaker 1: places where it goes crazy.
• 45:39
  Speaker 2: Does every black hole have a singularity in it?
• 45:42
  Speaker 1: Every black hole has a singularity in it according to
• 45:45
  Speaker 1: general relativity. Now we don't think general relativity is correct.
• 45:49
  Speaker 1: In fact, it probably breaks down at exactly this place,
• 45:53
  Speaker 1: the singularity. So in reality in our universe, are there
• 45:57
  Speaker 1: places where you can't predict the future? Probably not, because
• 46:00
  Speaker 1: all of this is probably wrong, and we need quantum
• 46:02
  Speaker 1: gravity to describe what's going on here. And in fact,
• 46:05
  Speaker 1: singularity is an example of why we think general relativity
• 46:08
  Speaker 1: is probably wrong, because singularities, they are very existence is
• 46:12
  Speaker 1: in conflict with quantum mechanics, and quantum mechanics itself is
• 46:15
  Speaker 1: actually kind of deterministic. It doesn't predict the exact outcome,
• 46:19
  Speaker 1: but it predicts the probabilities in a very deterministic and
• 46:22
  Speaker 1: specific way. So this would also mess up the determinism
• 46:25
  Speaker 1: of quantum mechanical probabilities. So most is just think, yeah,
• 46:29
  Speaker 1: this is interesting little quirk in the calculations when you
• 46:33
  Speaker 1: assume the universe is classical, but nobody thinks that it is,
• 46:36
  Speaker 1: and so it's probably irrelevant to reality. But it is
• 46:40
  Speaker 1: a fascinating little corner of general relativity where predictions are
• 46:44
  Speaker 1: just not possible. And that's why spinning black holes, which
• 46:47
  Speaker 1: are probably in reality much more common than non spinning
• 46:51
  Speaker 1: black holes, have this two stage structure. They have an
• 46:54
  Speaker 1: event horizon and the caushi horizon.
• 46:57
  Speaker 2: Okay, So, given what you just said, if you had
• 47:01
  Speaker 2: to guess if any of this stuff is actually going on,
• 47:06
  Speaker 2: would you guess zero? Okay? Got it? Okay?
• 47:09
  Speaker 1: Yeah, all right, Joe, thank you for your curiosity about
• 47:13
  Speaker 1: spitting black holes and inner horizons and Cawshi manifolds. Let
• 47:17
  Speaker 1: me know if that answered your question.
• 47:19
  Speaker 3: Wow, No, I think I got about eighty percent of that.
• 47:24
  Speaker 3: A spinning black hole with an event horizon where causality
• 47:28
  Speaker 3: breaks down. That's fade worse than spaghetification, I think. But
• 47:33
  Speaker 3: maybe spaghetification is the future that we can't predict with certainty,
• 47:39
  Speaker 3: although I think I'd be pretty certain to avoid the
• 47:44
  Speaker 3: caushi horizon.
• 47:46
  Speaker 2: Thanks a lot, Thank you everyone for sharing your curiosity
• 47:55
  Speaker 2: with us. If you have a question you'd like to
• 47:57
  Speaker 2: send our way, send it at questions as Danielankelly dot org.
• 48:01
  Speaker 2: We would love to interact with you.
• 48:04
  Speaker 1: Please do write to us. We're not just saying.
• 48:06
  Speaker 2: That, and we would massively appreciate it if you'd be
• 48:09
  Speaker 2: willing to leave us a review on Spotify, Apple, on
• 48:12
  Speaker 2: whatever podcast app it is that you listen to us on.
• 48:15
  Speaker 2: It helps other people find the show.
• 48:17
  Speaker 1: And if you reviewed us several years ago and you're
• 48:19
  Speaker 1: thinking that doesn't apply to me, come back review us
• 48:21
  Speaker 1: again to the new show.
• 48:23
  Speaker 2: Thanks