Latest / Daniel and Kelly’s Extraordinary Universe / What's Inside The Earth?

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What's Inside The Earth? · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: Hey, Daniel, what's your favorite part of the pizza. Oh,
• 0:10
  Speaker 1: I'm all about the crust. The crust makes the pizza.
• 0:13
  Speaker 1: You're crust guy. Huh, Well, it turned out that's just
• 0:16
  Speaker 1: like a planet. All the interesting stuff in a planet
• 0:18
  Speaker 1: like ours happens on the crust. That's where the good
• 0:22
  Speaker 1: stuff is, right. You know that totally makes sense because
• 0:24
  Speaker 1: I can't count the number of times I've burnt my
• 0:26
  Speaker 1: tongue on the hot lava of tomato sauce on pizza.
• 0:31
  Speaker 1: It's like a molten core, all that cheese exactly exactly,
• 0:36
  Speaker 1: and you always want to bite it before it's cooled
• 0:38
  Speaker 1: off and turned into a nice place to live. You know,
• 0:40
  Speaker 1: you always got to get in there. But you know,
• 0:43
  Speaker 1: you're right, the crust is very important, and you know
• 0:45
  Speaker 1: that's where you hold the pizza. That's where we hold
• 0:47
  Speaker 1: onto our planet. So it's it's a big deal. Yeah.
• 0:50
  Speaker 1: What about what about the cheese stuff crust? It's like
• 0:55
  Speaker 1: a crust in a crust. Yeah, what is the what
• 0:59
  Speaker 1: is the geological analogy of cheese stuffed crust? Right, that's
• 1:05
  Speaker 1: like underwater, that's like a sub subterranean lakes or something
• 1:10
  Speaker 1: of cheese. Yeah, well, I'm like those intolerant. So Hi,
• 1:30
  Speaker 1: I'm Orge and I'm Daniel, and welcome to our podcast,
• 1:34
  Speaker 1: Pizzas in the Universe. Daniel and Jorge explain what makes
• 1:37
  Speaker 1: a pizza a pizza and what doesn't make a pizza.
• 1:41
  Speaker 1: We have no idea. We do have some idea based
• 1:44
  Speaker 1: on my deep expertise of being a particle physicist. I'm
• 1:47
  Speaker 1: here to expound on what's a pizza and what's not
• 1:50
  Speaker 1: a pizza. Now, welcome to our podcast. Daniel and Jorge
• 1:53
  Speaker 1: Explain the Universe, a production of I Heart Radio in
• 1:57
  Speaker 1: which we find topics here, there, everywhere and break them
• 2:00
  Speaker 1: down so that you can understand them while you enjoy
• 2:03
  Speaker 1: your pizza. That's right. We're also the authors of the
• 2:05
  Speaker 1: book We have No Idea, which you can find in
• 2:08
  Speaker 1: bookstores and online or just borrow from your grandma because
• 2:11
  Speaker 1: she read it and she loved it. She loved it,
• 2:14
  Speaker 1: she told us. Are you in touch with everybody's grandma?
• 2:19
  Speaker 1: I'm in touch with the cosmic grandma. Like the you
• 2:22
  Speaker 1: like the idea of imagining all of a sudden imagining
• 2:24
  Speaker 1: some like you know underground Internet Grandma network that you've
• 2:28
  Speaker 1: typed into. It's just a giant book. Club. Basically, can
• 2:33
  Speaker 1: you mobilize them in emergencies to do something important? Yes,
• 2:37
  Speaker 1: there's I have a big red button here, he says,
• 2:41
  Speaker 1: Raise grandma army. Yeah, somebody's hungry quick, somebody hasn't had lunch,
• 2:50
  Speaker 1: somebody's looking thin. Cook. Cook. But not today, We're going
• 2:55
  Speaker 1: to not talk about something that's out there in the
• 2:58
  Speaker 1: universal mystery. But today we're going to focus on a
• 3:01
  Speaker 1: question very near us and actually underneath you. That's right.
• 3:05
  Speaker 1: Today we're going to talk about where we all live,
• 3:08
  Speaker 1: the place that you call home. Today's topic is what's
• 3:17
  Speaker 1: inside the Earth or what is the Earth made out of?
• 3:21
  Speaker 1: We we live on it, we walk in it, we
• 3:23
  Speaker 1: running it, we swim in it. But do how many
• 3:25
  Speaker 1: people know what this giant ball that we're riding around
• 3:31
  Speaker 1: space on is made out of? Yeah? It's a special place.
• 3:35
  Speaker 1: I mean, as far as we know so far, it's
• 3:38
  Speaker 1: host to all life that we've ever seen. Right, everything
• 3:42
  Speaker 1: anybody has ever touched or tasted has been on Earth.
• 3:45
  Speaker 1: So it's an important place. You know. It's the spaceship
• 3:48
  Speaker 1: we are riding through the universe on, and there's a
• 3:51
  Speaker 1: lot going on, right, you can't just ignore it, especially
• 3:53
  Speaker 1: for those of us living in California. You know, we're
• 3:55
  Speaker 1: wondering about like earthquakes and all sorts of crazy stuff,
• 3:59
  Speaker 1: So it's important to know what's going on inside the earth. Yeah,
• 4:02
  Speaker 1: magnetic fields and having to move around and shielding us
• 4:06
  Speaker 1: from cosmic rays. It's all because of what's going on inside.
• 4:10
  Speaker 1: Mm hmmm um. You know, continental drift and super volcanoes
• 4:15
  Speaker 1: and all sorts of stuff. If the Earth was just
• 4:17
  Speaker 1: a quiet lump of rocket, wouldn't be quite so exciting
• 4:20
  Speaker 1: to live on. Yeah. And lava, of course, lava. Who
• 4:24
  Speaker 1: doesn't love a lava? Who doesn't love a love a lamp?
• 4:28
  Speaker 1: You know? I was teaching ones and I usually like
• 4:31
  Speaker 1: to open my class with asking people for random questions,
• 4:35
  Speaker 1: you know, get them warmed up, and who's gonna totally
• 4:37
  Speaker 1: random question? Right? And somebody wants to asked me what
• 4:41
  Speaker 1: does lava taste like? That is a good random question.
• 4:48
  Speaker 1: I said pain, Pure pain tastes like pain, tastes like
• 4:53
  Speaker 1: charred tongue. No, I said pineapples. It tastes like pineapples,
• 4:59
  Speaker 1: does it? I have no idea what lava tastes like. No,
• 5:05
  Speaker 1: in like the bill of second between lava, like scorching
• 5:09
  Speaker 1: your tongue. Um it probably you just taste like rock, right,
• 5:13
  Speaker 1: It's just probably like living a rock, salty, salty, exactly metallic. Yeah,
• 5:19
  Speaker 1: So people out there, do not do this investigation. Do
• 5:22
  Speaker 1: not approach lava, do not play with lava, do not
• 5:25
  Speaker 1: lick lava. Um I probably doesn't taste like pineapple maybe
• 5:29
  Speaker 1: in Hawaii actually, And so we got into this question
• 5:32
  Speaker 1: a little bit, Daniel, because we were wondering, we were
• 5:35
  Speaker 1: thinking about ideas with this up for an episode, and
• 5:37
  Speaker 1: we were wondering, what would happen if you dug a
• 5:40
  Speaker 1: hole through the entire Earth and jumped into it? Right,
• 5:43
  Speaker 1: that's a that's a pretty weird question. Yeah, And you know,
• 5:46
  Speaker 1: this is the kind of thing you see in science
• 5:48
  Speaker 1: fiction all the time, you know, journey to the Center
• 5:50
  Speaker 1: of the Earth, and um I was watching gravity falls
• 5:53
  Speaker 1: and they have the bottomless pit, you know, they jump
• 5:55
  Speaker 1: in and fall forever. And so it's a trope that
• 5:58
  Speaker 1: you see a lot of times. You know, people wonder
• 5:59
  Speaker 1: like can you get into the center of the Earth,
• 6:01
  Speaker 1: And so it's a fun It's also a fun physics
• 6:04
  Speaker 1: question I ask in my freshman physics class sometimes, like
• 6:07
  Speaker 1: what would happen if you drill the hole all the
• 6:08
  Speaker 1: way through the earth and then jumped inside. You know,
• 6:11
  Speaker 1: so for from the point of view of like gravitation. Yeah,
• 6:13
  Speaker 1: but you know, I'm an engineer, so I kind of
• 6:15
  Speaker 1: got hung up on the question of how you would
• 6:17
  Speaker 1: even make that whole or could you have a tunnel
• 6:19
  Speaker 1: that goes through the center of the earth? And would
• 6:22
  Speaker 1: you let us to the question what what is inside
• 6:23
  Speaker 1: the earth? What's going on? What would you drill a
• 6:26
  Speaker 1: hole through? Yeah? Exactly is it hard or easy? Do
• 6:29
  Speaker 1: you like dig down a hundred meters and then you
• 6:31
  Speaker 1: know it's just like a big pile of soft stuff,
• 6:34
  Speaker 1: or is it like diamond down there, or you know
• 6:36
  Speaker 1: it's impossible to dig into? Yeah, this is pretty interesting stuff. Yeah,
• 6:40
  Speaker 1: so we might get to that question of what would
• 6:42
  Speaker 1: happen if you jump through a whole the go through
• 6:45
  Speaker 1: the entire earth. But but today's episode, we'll we'll talk
• 6:48
  Speaker 1: about the earlier question, which is what is the earth
• 6:50
  Speaker 1: made out of? That's right, We'll take you on a
• 6:52
  Speaker 1: tour from the very top all the way to the
• 6:55
  Speaker 1: very center of the earth. Yeah, and as usual, we
• 6:57
  Speaker 1: were wondering how many of you out there know the
• 6:59
  Speaker 1: answer to this question? How many people know what's inside
• 7:02
  Speaker 1: to earth? And so Daniel went out there as usual,
• 7:05
  Speaker 1: out into the street and ask people, random strangers what
• 7:08
  Speaker 1: they thought was inside to Earth. Here's what people had
• 7:12
  Speaker 1: to say. Is the Earth just one big rock or
• 7:14
  Speaker 1: is it more complex under our feet? There are more
• 7:18
  Speaker 1: complex features below our feet and something fel like the mantle,
• 7:23
  Speaker 1: um core, cross shoe as lissile spear, messile scree or
• 7:30
  Speaker 1: something like that. I know that there's it's not just
• 7:34
  Speaker 1: a big rock, but yeah, I don't know the components
• 7:37
  Speaker 1: of what they send it. Well. I think there's like
• 7:40
  Speaker 1: different layers of rocks. But that's it, okay, like different,
• 7:47
  Speaker 1: just different layers and different just difficult that the Earth
• 7:52
  Speaker 1: it's not just one of big rock, Okay, it's like
• 7:54
  Speaker 1: layers and like there's like dirt rock, gravel, and thought
• 7:59
  Speaker 1: it's up and they're like for some reason, like my
• 8:04
  Speaker 1: mind went to like minecraft. So then like the should
• 8:11
  Speaker 1: be like lava area across is like made out of
• 8:13
  Speaker 1: like different minerals, like different rocks. And well around the earth,
• 8:19
  Speaker 1: the first layers the crust, then um there's soft softer
• 8:25
  Speaker 1: more hot rock um and there are two layers of
• 8:29
  Speaker 1: magma um at the center of the core of the Earth. Well,
• 8:32
  Speaker 1: it sounds like most people, um just sort of guess
• 8:35
  Speaker 1: that they just made out of rock and dirt and
• 8:38
  Speaker 1: some lava. Yeah, a lot of people know there's like
• 8:40
  Speaker 1: rock and dirt and gravel. And I love the people
• 8:42
  Speaker 1: who refer to Minecraft as their their reference. But you know,
• 8:45
  Speaker 1: there's there's some evidence they're like, you know, Minecraft is
• 8:48
  Speaker 1: a little bit educationally, you dig down deep enough in
• 8:50
  Speaker 1: Minecraft and you get to Magma, So yeah, good job Minecraft. Yeah,
• 8:54
  Speaker 1: and zombies, and that's what that's what I know about minecrafts. Also, Minecraft,
• 9:01
  Speaker 1: you know, says that the universe is pixelated, and I'm
• 9:03
  Speaker 1: pretty sure they get that right. Also, so you know,
• 9:05
  Speaker 1: the physics of Minecraft is really pretty solid, interesting, just
• 9:09
  Speaker 1: maybe a few orders of magnitude exactly. They need a
• 9:12
  Speaker 1: few more bits, you know, it's not an eight bit
• 9:14
  Speaker 1: universe we live in. Well, there's the idea that we
• 9:17
  Speaker 1: maybe we are all in a video game, right, that's true. Yeah,
• 9:20
  Speaker 1: we could certainly be in a simulation. Um My kids
• 9:23
  Speaker 1: watched Ready Player one last week and they looked at
• 9:26
  Speaker 1: it and they were like, whoa, that's pretty cool. He
• 9:28
  Speaker 1: can almost live inside that game. And then you could
• 9:31
  Speaker 1: see the idea of being formed in their minds. Wait,
• 9:34
  Speaker 1: what if we were inside a game right now? Really?
• 9:36
  Speaker 1: Whoa And they weren't even stoned. I promise they weren't
• 9:41
  Speaker 1: even stone. They came up with that question totally sober. Well,
• 9:46
  Speaker 1: that's a that's a topic of a podcast we already recorded,
• 9:49
  Speaker 1: is that are we living in a video game? But
• 9:51
  Speaker 1: today's we're going to focus on what's in what's in
• 9:53
  Speaker 1: the earth. So take us through, Dannuel. If we start
• 9:56
  Speaker 1: where we are now, sitting or standing or right on,
• 10:00
  Speaker 1: and we go down, what what do we hit first? Well,
• 10:03
  Speaker 1: the thing to remember is that the Earth is huge, right,
• 10:07
  Speaker 1: So it seems like almost flat because the curvature is
• 10:10
  Speaker 1: so small. That's just because the Earth is enormous, right,
• 10:13
  Speaker 1: And so remember as we take our tour down to
• 10:16
  Speaker 1: the center of the Earth, the scale of things from
• 10:18
  Speaker 1: us all the way down to the center is thousands
• 10:21
  Speaker 1: of kilometers, right. So that amazes me already when I
• 10:24
  Speaker 1: learned that the crust, this part that we stand on,
• 10:27
  Speaker 1: you know, the part that's like rock and whatever, that's
• 10:29
  Speaker 1: only like fifty kilometers thick, and it varies under the ocean,
• 10:34
  Speaker 1: it's even thinner, you know, the top amount everest. Of
• 10:36
  Speaker 1: course it's thicker, but it's like a tiny little shell.
• 10:39
  Speaker 1: It's like an eggshell around a yoke. And that's the
• 10:43
  Speaker 1: part that we live on. What do you mean, So
• 10:44
  Speaker 1: the first layer underneath our feet is called the crust?
• 10:48
  Speaker 1: Is that the official physics name? The crust, that's the
• 10:51
  Speaker 1: official physics slash pizza name. Yeah, it's the crust. That's
• 10:54
  Speaker 1: when you grab onto the planet from you know, what,
• 10:56
  Speaker 1: what what could you have instead of a crust? Well,
• 10:58
  Speaker 1: if you were like on you put her. For example,
• 11:00
  Speaker 1: Jupiter doesn't have a crust. It has like a metallic
• 11:03
  Speaker 1: hydrogen core and then like helium rain and then like
• 11:07
  Speaker 1: you know, liquid hydrogen oceans. And you know, there's no
• 11:10
  Speaker 1: like firm place you can really land. There's no rock
• 11:13
  Speaker 1: on Jupiter. It's just we're pretty lucky to be a
• 11:16
  Speaker 1: rocky planet that has some crust to it. Yeah, Jupiter
• 11:18
  Speaker 1: is just kind of like a big blob of wet stuff.
• 11:22
  Speaker 1: It's it's like a sun that never took off right um.
• 11:26
  Speaker 1: And and you know, earlier in Earth, in the life
• 11:28
  Speaker 1: of Earth, when it was really really young, it was
• 11:30
  Speaker 1: just basically a ball of magma, and so the surface
• 11:33
  Speaker 1: was all you know, hot molten rock. There was no
• 11:36
  Speaker 1: cold crust to walk on Earth, and so the Earth
• 11:40
  Speaker 1: yeah verver early on. Oh we form from but I
• 11:44
  Speaker 1: thought we formed from like bits of stuff out there
• 11:47
  Speaker 1: in space. How did it try into a big ball
• 11:50
  Speaker 1: of lava? Yeah, so we did form from big from
• 11:53
  Speaker 1: bits of stuff. Right, that's rewind a few billion years,
• 11:56
  Speaker 1: and you have like a huge cloud of gas and dust, right,
• 11:59
  Speaker 1: and rubble that's all left over from other stars that
• 12:02
  Speaker 1: have that you know, had you know, billions of years
• 12:05
  Speaker 1: to burn and and then explode and spew their stuff
• 12:07
  Speaker 1: into space, and then gravity gradually gathers it back together.
• 12:11
  Speaker 1: And then gravity made the Sun, and he gathered all
• 12:13
  Speaker 1: the extra bits together into the planets. And the gravitational pressure, right,
• 12:17
  Speaker 1: the collision between the stuff and the pressure pulling this
• 12:19
  Speaker 1: stuff together, that's what That's what creates a lot of
• 12:22
  Speaker 1: the heat. Also, there's when you have a really hot
• 12:25
  Speaker 1: stuff inside the Earth and you have things like uranium
• 12:28
  Speaker 1: and all sorts of other stuff emitting radiation. So it
• 12:31
  Speaker 1: makes the Earth hot. Right. The gravitational pressure and the
• 12:34
  Speaker 1: radiation from the core made the young Earth very very
• 12:37
  Speaker 1: nasty and hot and wet. So no place you can
• 12:39
  Speaker 1: go for a nice walk. It's it's being squeezed down in. Okay.
• 12:43
  Speaker 1: So the first layer is this good thing you call
• 12:46
  Speaker 1: the crust, and it's made out of just like rocks,
• 12:49
  Speaker 1: and like the same rocks we see on the surface. Yeah,
• 12:51
  Speaker 1: I mean it is the surface, right, and it goes
• 12:54
  Speaker 1: down about you know, thirty five kilometers fifty kilometers depends
• 12:57
  Speaker 1: on exactly where you are. And people have tried I
• 13:00
  Speaker 1: love this. People have tried to dig through the crust
• 13:03
  Speaker 1: right to see like how far could we go? How
• 13:05
  Speaker 1: deep could we can we dig? You know? And um,
• 13:08
  Speaker 1: the Russians actually have won that race back when there
• 13:12
  Speaker 1: was a Soviet Union. They dug a shaft which was
• 13:14
  Speaker 1: I think twelve kilometers down, so it's like, you know,
• 13:17
  Speaker 1: maybe a third or a fourth of the way through
• 13:19
  Speaker 1: the crust. It was almost like a pin preak. It did.
• 13:22
  Speaker 1: They didn't really get through the crust. Yeah, And you know,
• 13:25
  Speaker 1: all of these things, these little holes we're talking about
• 13:27
  Speaker 1: the size of the crust, even like the peak of
• 13:29
  Speaker 1: Mount Everest, all these things are tiny features compared to
• 13:33
  Speaker 1: the size of the earth. As you're saying, it's like
• 13:35
  Speaker 1: a pin prick. And you remember if you held the
• 13:37
  Speaker 1: Earth in your hand. None of the features on the
• 13:40
  Speaker 1: Earth would even be recognizable. They might not even be observable.
• 13:43
  Speaker 1: You could probably run your thumb over the Earth and
• 13:46
  Speaker 1: not even tell where Mount Everest was. It would be
• 13:50
  Speaker 1: like it would look shiny, like a shiny marble, Yeah, shiny,
• 13:53
  Speaker 1: slightly wet marble exactly, um and so, and and the
• 13:57
  Speaker 1: outer layers this crust which is only you know, thirty
• 14:00
  Speaker 1: to fifty kilometers thick, so it's really pretty thin. So
• 14:03
  Speaker 1: we would see like just regular dirt and rocks and
• 14:06
  Speaker 1: stuff for fifty kilometers. That's a lot that I mean,
• 14:10
  Speaker 1: that's like from yeah, I know, and it's it's this
• 14:12
  Speaker 1: conflict in scales, right, Like fifty kilometers seems like a lot,
• 14:15
  Speaker 1: and we try to dig through it and it's too far, right,
• 14:18
  Speaker 1: and so on one hand, it feels like a lot.
• 14:19
  Speaker 1: On the other hand, it's a tiny little fraction. But
• 14:22
  Speaker 1: this is the kind of thing you discover when you
• 14:24
  Speaker 1: were exploring physics and space and the universe, right, all
• 14:26
  Speaker 1: these conflict in scales, Like the Earth is huge, but
• 14:29
  Speaker 1: actually it's tiny compared to the Sun, which is huge good,
• 14:32
  Speaker 1: which is actually tiny you compared to the galaxy, right,
• 14:35
  Speaker 1: It's one of the things I love about physics. Yeah,
• 14:38
  Speaker 1: and maybe you can drive fift kilometers in your car
• 14:41
  Speaker 1: in less than an hour, but if you try to
• 14:44
  Speaker 1: dig fifty kilometers down, it would take you a little
• 14:47
  Speaker 1: bit longer. Yeah. I don't even know how they did it.
• 14:49
  Speaker 1: This this hole that they dug in the Soviet Union,
• 14:51
  Speaker 1: that's twelve kilometers deep. It's only like twenty something centimeters wide, right,
• 14:57
  Speaker 1: so they have to have like a crazy drill bit
• 15:00
  Speaker 1: and you know, they probably had a really long extension chord,
• 15:04
  Speaker 1: like a twelve kilometer extension chords, you know what I mean,
• 15:08
  Speaker 1: probably had like Christmas lights and everything. They're using every
• 15:10
  Speaker 1: extension chord. And then probably they were in the Soviet Union.
• 15:14
  Speaker 1: That's why they went broke. They're like, everybody, don't use
• 15:17
  Speaker 1: any electronics, give us your chord. In Russia, whole drills
• 15:21
  Speaker 1: you I don't even know what that means exactly. So
• 15:26
  Speaker 1: the crust is fifty kilometers thick. We've only barely pricked
• 15:29
  Speaker 1: the like the outer bits of it, right, the deepest
• 15:32
  Speaker 1: minds hardly scratched the surface. And it's a tiny fraction
• 15:35
  Speaker 1: of the size of the Earth. Wow, it's just like
• 15:37
  Speaker 1: a little x X shell really exactly. It's like if
• 15:42
  Speaker 1: you ordered a pizza and the crust was like almost invisible,
• 15:46
  Speaker 1: like you could just barely grab it before you got
• 15:48
  Speaker 1: the tomato sauce, right, it would be like a I
• 15:52
  Speaker 1: hate it when they cut pieces and squares because then
• 15:54
  Speaker 1: you get pieces without crust. You hate that. That's the
• 15:57
  Speaker 1: best way to cut pizza. What are he's talking about? No,
• 15:59
  Speaker 1: they you don't get any crust. I thought you were
• 16:01
  Speaker 1: a crust man. Oh yeah, but you have crust on
• 16:03
  Speaker 1: the bottom. I mean that's how the crust is for
• 16:06
  Speaker 1: to hold up the pizza. The part of the crust
• 16:09
  Speaker 1: without tomato and cheese is wasted to dry. I thought, okay, well,
• 16:13
  Speaker 1: well there'll be another episode. Daniel and Horry argue, aby pizza. Okay,
• 16:21
  Speaker 1: so let's say you you dig through fifts down and
• 16:24
  Speaker 1: you break through the crust. What what what do you?
• 16:27
  Speaker 1: What do you find? Then you get to something they
• 16:29
  Speaker 1: call the mantle, and the mantle is basically rocks that
• 16:32
  Speaker 1: are being squeezed really hard, you know, by gravitational pressure
• 16:35
  Speaker 1: by the crust on top of it, and they're like
• 16:39
  Speaker 1: not fluid but not exactly solid. It's like a bunch
• 16:42
  Speaker 1: of rocks that are rubbed together really hard and and um,
• 16:47
  Speaker 1: they can slide around a little bit. Wait, what do
• 16:49
  Speaker 1: you mean fluid? They're like, um, like grains of sand
• 16:53
  Speaker 1: is fluid or or like really the rocks themselves deform
• 16:57
  Speaker 1: and and and flow. I think it's a little bit
• 17:00
  Speaker 1: of both. I think it's a little bit like the
• 17:02
  Speaker 1: way glaciers flow. Right. You hear about glaciers like flowing
• 17:06
  Speaker 1: across the surface of the earth and carving out mountains, right,
• 17:08
  Speaker 1: and then you go visit a glacier and it's just
• 17:10
  Speaker 1: a big piece of ice and you're like, how is
• 17:12
  Speaker 1: this thing flowing? Right? Well, it flows very slowly, um,
• 17:16
  Speaker 1: you know, like uh, like glass flows or something like
• 17:19
  Speaker 1: if you went up to it and touch it, it
• 17:20
  Speaker 1: would look feel solid, but over time it would be deforming.
• 17:26
  Speaker 1: And you know, I think there's elements of it that
• 17:27
  Speaker 1: are more liquid and elements elements of it that are
• 17:30
  Speaker 1: more solid. Right. That's why we have magma that creeps
• 17:33
  Speaker 1: up through holes in the crust and turns into lava
• 17:35
  Speaker 1: when it's abused out in volcanoes. By the way, huge
• 17:38
  Speaker 1: Internet debate over whether what to call magma and what
• 17:41
  Speaker 1: to call lava. Is there really that's what you mean.
• 17:44
  Speaker 1: People are you? You mean? People are you in the
• 17:46
  Speaker 1: internet over things that are not that important? Someone on
• 17:50
  Speaker 1: the internet was wrong. I can't go to sleep. It's
• 17:53
  Speaker 1: magma when it's still underground, and as soon as it
• 17:56
  Speaker 1: comes above ground, then you call it lava. So if
• 17:59
  Speaker 1: you say that a volcano pews out magma, you're gonna
• 18:01
  Speaker 1: go like a thousand people online telling you you're wrong,
• 18:04
  Speaker 1: that's actually lava or underground. Well, let's let's be sure
• 18:11
  Speaker 1: here to to not anger anyone on the internet. That's
• 18:15
  Speaker 1: not the point of this podcast is to annoy people
• 18:17
  Speaker 1: and piss them off. So the dismantle, this kind of
• 18:21
  Speaker 1: liquid rock um is super thick, you're telling me earlier. Yeah,
• 18:25
  Speaker 1: it's like almost three kilometers thick. So it's a huge
• 18:29
  Speaker 1: chunk of the earth. Right, it's much much thicker than
• 18:31
  Speaker 1: the crust. So if you were to somehow be able
• 18:34
  Speaker 1: to dig all the way through the crust, right, which
• 18:36
  Speaker 1: seems almost impossible, you can get to the mantle, and
• 18:39
  Speaker 1: the mantle is like, is really thick. So that's a
• 18:42
  Speaker 1: huge part of the drilling. If you wanted to get
• 18:43
  Speaker 1: down to the center of the earth, you'd be like
• 18:45
  Speaker 1: drilling from Florida to California. Yeah, but it'd be super
• 18:49
  Speaker 1: hot and super high pressure the whole time, right, So
• 18:51
  Speaker 1: it's not just like a nice drive across country, right,
• 18:54
  Speaker 1: it's really difficult environment. You need a lot of extension
• 18:59
  Speaker 1: cords air conditioning, that's right. And it's because the mantle
• 19:04
  Speaker 1: is not actually solid that we have earthquakes and tectonic
• 19:08
  Speaker 1: activities and mountains and stuff like that. It's always shifting
• 19:11
  Speaker 1: and moving mm hmmm. Yeah. You can sort of think
• 19:14
  Speaker 1: of the crust has broken into pieces that are floating
• 19:18
  Speaker 1: in slow motion on top of this, you know, semi liquid,
• 19:22
  Speaker 1: semi solid mantle magma business, right, slide around and bang
• 19:26
  Speaker 1: into each other. And all the interesting stuff that happens
• 19:28
  Speaker 1: on the surface is because of that action. I see,
• 19:31
  Speaker 1: because you're saying it's like the crust is pretty solid,
• 19:35
  Speaker 1: so we are kind of like floating icebergs kind of, right,
• 19:38
  Speaker 1: so that the crust is solid, but the rocks underneath
• 19:40
  Speaker 1: is fluid. And so when you move these like solid pieces,
• 19:44
  Speaker 1: that's when you get the crunching and the earthquakes. M
• 19:47
  Speaker 1: And it's pretty thick, which is good because you wouldn't
• 19:49
  Speaker 1: want to drive, you know, an entire tectonic plate through
• 19:52
  Speaker 1: something like you know, as as thin as water, um
• 19:55
  Speaker 1: and things, we get pretty crazy. This mantle is really thick.
• 19:58
  Speaker 1: It's like ten to the ten times thicker than tar, right,
• 20:01
  Speaker 1: so it's not something that you can easily sluice through
• 20:06
  Speaker 1: like dancer. Yeah, they have some measure of thickness, you know,
• 20:09
  Speaker 1: the viscosity. Basically, it's more viscous than tar by a
• 20:13
  Speaker 1: factor of ten to the ten. Oh, I see, I
• 20:15
  Speaker 1: see viscus. Okay, it's it's not um. If you had
• 20:18
  Speaker 1: a bowl of it, how long would it take a
• 20:19
  Speaker 1: drop to form and drop out? Actually, that's fascinating. Have
• 20:22
  Speaker 1: you seen this experiment, the tar pitch experiment. Yeah? Yeah,
• 20:26
  Speaker 1: like it it um. It's like something so thick it
• 20:28
  Speaker 1: just hangs there for a long time. Yeah. It takes
• 20:31
  Speaker 1: like a you know, two decades for a drop to
• 20:33
  Speaker 1: form and fall. And they've been doing the experiment for like,
• 20:35
  Speaker 1: I don't know, eighty years or something, and in eighty
• 20:37
  Speaker 1: years they had like four four drops fall, and every
• 20:40
  Speaker 1: time one is about to fall, everybody's like super excited
• 20:43
  Speaker 1: about it. Anyway, this stuff is is much thicker. We
• 20:47
  Speaker 1: take billions of years for a single drop to form Oh.
• 20:49
  Speaker 1: So let's say so we were we're digging our our
• 20:52
  Speaker 1: tunnel through the center of the Earth. We would dig
• 20:55
  Speaker 1: a tunnel and we would be safe. We wouldn't move
• 20:57
  Speaker 1: with it, like with the tunnel closing on itself or something. Well,
• 21:01
  Speaker 1: there's a lot of pressure, right, Yeah, it's really thick,
• 21:03
  Speaker 1: you're right, so it might hold itself up. But there's
• 21:05
  Speaker 1: also a huge amount of pressure. Right, there's tons and
• 21:08
  Speaker 1: tons and tons of stuff bearing down. So I think
• 21:11
  Speaker 1: that that tunnel would have to be really strong to survive.
• 21:14
  Speaker 1: And that's my bone with like all those movies about
• 21:16
  Speaker 1: Journey to the Center of the Earth, I'm like, where's
• 21:18
  Speaker 1: all the stuff? You know? It always seems to be
• 21:20
  Speaker 1: like fluffy empty space, like they're just like digging through
• 21:24
  Speaker 1: styrofoam peanuts or something. But in reality, if you if
• 21:28
  Speaker 1: you dug a truck tunnel, like the walls would cave
• 21:31
  Speaker 1: in really quickly because it's under so much pressure. Right, Yeah,
• 21:35
  Speaker 1: you need some super material to stabilize the walls. Yeah,
• 21:38
  Speaker 1: at of antium probably. All right, let's keep digging down,
• 21:42
  Speaker 1: but first let's take a quick break. All right, So
• 21:56
  Speaker 1: we're digging through to the center of the Earth, and
• 22:00
  Speaker 1: we we passed the crust, and we passed the mantle.
• 22:03
  Speaker 1: We're now about three thousand kilometers into the earth, and
• 22:07
  Speaker 1: then we things change right after the mantle. Now we
• 22:11
  Speaker 1: hit a new layer which is called the liquid outer core. Yeah, exactly.
• 22:15
  Speaker 1: And you might wonder, like why do they give these
• 22:17
  Speaker 1: things different names? Is the Earth really just continuous? And
• 22:20
  Speaker 1: this is just like scientists putting labels on stuff, because
• 22:23
  Speaker 1: scientists love putting labels on stuff, like is there a boundary? Really?
• 22:26
  Speaker 1: Like it doesn't to do the things suddenly changed when
• 22:29
  Speaker 1: you keep digging, they kind of do. Yeah, there really
• 22:31
  Speaker 1: are surfaces there, right, Like things do change. The mantle
• 22:34
  Speaker 1: really is different from the crust, and the crust and
• 22:37
  Speaker 1: the mantle is really also different from this from this core,
• 22:40
  Speaker 1: both the liquid outer core and then the solid intercore.
• 22:43
  Speaker 1: There really is a change there, which is fascinating. Right,
• 22:45
  Speaker 1: Why isn't it continuous? Why isn't it smooth? Why are
• 22:48
  Speaker 1: there these edges? But there are? And so you get
• 22:50
  Speaker 1: to this place where it's like liquid rock, you know,
• 22:53
  Speaker 1: it's like molten metal and rock. It's like incredible because
• 22:57
  Speaker 1: it's so hot and undre's so much pressure that basically
• 23:00
  Speaker 1: all the rocks melt, right, and you get lava. Yeah,
• 23:04
  Speaker 1: that's right. And remember magma magma, magma magma. Dude, there's
• 23:07
  Speaker 1: no lava that. And so it's really hot and really dense,
• 23:11
  Speaker 1: and so you've got this liquid metal and and all
• 23:14
  Speaker 1: sorts of rock and all this stuff mixing around in there, right,
• 23:16
  Speaker 1: it's it's like super duper danse right. Yeah, it's you're saying.
• 23:19
  Speaker 1: It's it's a rams per cubic meter cub oh, I
• 23:23
  Speaker 1: see ten thousand, So it's like five tons or so
• 23:28
  Speaker 1: in a in a in a suitcase size. Yeah, well
• 23:31
  Speaker 1: do you have a cubic meter size suitcase? Wow? I
• 23:34
  Speaker 1: really don't want to travel with you. Man, it's only
• 23:38
  Speaker 1: a cubic meter. I think you could probably fit your
• 23:42
  Speaker 1: whole family into a cubic meter man, yes, definitely a
• 23:48
  Speaker 1: lot um. Anyway, it's pretty dense down there, it's pretty hot,
• 23:51
  Speaker 1: it's pretty nasty, and but that's important. Right. If it
• 23:54
  Speaker 1: wasn't liquid down there, then you couldn't get all sorts
• 23:57
  Speaker 1: of interesting stuff happening, like magnetic fields. Oh that this
• 24:00
  Speaker 1: is where the magnetic field comes from. Is this liquid
• 24:04
  Speaker 1: molten core? It's really a layer, right, because were still
• 24:08
  Speaker 1: not down to the core. That's right, this is the
• 24:10
  Speaker 1: liquid outer core. And um, we don't really understand the
• 24:13
  Speaker 1: earth magnetic field very well. And for those of you
• 24:15
  Speaker 1: interested in that, we have a whole awesome podcast episode
• 24:18
  Speaker 1: just about the magnetic field. But a critical thing for
• 24:21
  Speaker 1: having a magnetic field is having a conducting fluid, so
• 24:24
  Speaker 1: a fluid that can conduct electricity and move around. And
• 24:28
  Speaker 1: so we think that like currents in this inner bits,
• 24:31
  Speaker 1: inner liquid bits of the Earth are what provides the
• 24:34
  Speaker 1: basically the motion for the magnetic field of the Earth. Oh,
• 24:38
  Speaker 1: it acts like a giant um like a giant solenoid
• 24:41
  Speaker 1: kind of right, like a giant. It's like a more
• 24:44
  Speaker 1: a giant electro magnet. You know, there's currents and they're
• 24:47
  Speaker 1: spinning and that generates a magnetic field, which causes more currents,
• 24:50
  Speaker 1: which causes more spinning, which causes more magnetic fields called
• 24:53
  Speaker 1: the dynamo. It's pretty cool. Wow. It's like it's like
• 24:57
  Speaker 1: we do, haven't. It's like we have an engine in
• 24:59
  Speaker 1: the middle of Earth. Yeah, we do exactly, and it's
• 25:02
  Speaker 1: a geological sized engine, right, I mean building something that
• 25:06
  Speaker 1: big would be incredible, right. This is these are structures
• 25:09
  Speaker 1: that are powered and that are operating and are bigger
• 25:12
  Speaker 1: than anything humans have ever constructed, right, so we should
• 25:15
  Speaker 1: definitely be in all of them. Wow. Okay, and then
• 25:18
  Speaker 1: if we if you make it through and it's and
• 25:20
  Speaker 1: again it's just like rock, But what does that mean?
• 25:22
  Speaker 1: Rock like an iron or metal like everything is just
• 25:26
  Speaker 1: kind of mixed in there. So it's mostly iron, and
• 25:28
  Speaker 1: there's a bunch of magnesium mixed in there also, and
• 25:31
  Speaker 1: then there's you know, just some rocks which you know,
• 25:33
  Speaker 1: silicate rocks and this kind of stuff. And remember where
• 25:35
  Speaker 1: all this comes from. Right? Where does all this iron
• 25:38
  Speaker 1: come from? It comes from the heart of a burning star. Right.
• 25:42
  Speaker 1: All of this was created infusion inside a star somewhere
• 25:45
  Speaker 1: else billions of years ago, which was then flung through
• 25:48
  Speaker 1: space and gathered back together. You know, the Earth doesn't
• 25:51
  Speaker 1: make any of these metals. There's no fusion happening here.
• 25:53
  Speaker 1: So everything that the Earth is made out of, that
• 25:55
  Speaker 1: you and me are made out of, had to be
• 25:57
  Speaker 1: formed somewhere else and then exploded through base. Wow, Like
• 26:02
  Speaker 1: there was an event sometime ago that created a whole
• 26:05
  Speaker 1: earthful of these metals. Yeah, exactly, Um, and huge quantities. Right,
• 26:11
  Speaker 1: It's not like you've got to scoot a spoonful of
• 26:13
  Speaker 1: iron here, like you have enormous amounts, and it's not
• 26:17
  Speaker 1: it's not also a coincidence that it's iron. It's not random.
• 26:20
  Speaker 1: Iron is the point where fusion stops being energetically favorable. Right.
• 26:25
  Speaker 1: It's the point in a star where squeezing things together
• 26:28
  Speaker 1: to make something heavier stops releasing energy, and then it
• 26:32
  Speaker 1: costs energy to make things heavier. So iron is sort
• 26:34
  Speaker 1: of the natural endpoint for fusion inside stars, which is
• 26:37
  Speaker 1: why you find so much of it, right, And so
• 26:40
  Speaker 1: you that's why most rocky planets out there would be
• 26:43
  Speaker 1: made out of iron. Right. I'm not sure about that,
• 26:45
  Speaker 1: but I think there must be a lot of iron
• 26:47
  Speaker 1: out there and rocky planets. Okay, so we're now about
• 26:52
  Speaker 1: almost six thousand kilometers into our tunnel to the center
• 26:56
  Speaker 1: of the Earth and bringing up snacks. Did you did
• 27:01
  Speaker 1: you pack one cubic meter? No, we're just going for
• 27:04
  Speaker 1: a Daniel. We're just going. We're holding our our hunger here.
• 27:08
  Speaker 1: It's like a diet trip. We're like, we're weight trip
• 27:12
  Speaker 1: to the center of the Earth. We're hoping there's a
• 27:14
  Speaker 1: McDonald's down down there at the center. Actually to spoil
• 27:18
  Speaker 1: the surprise. If you do make the center of the earth,
• 27:20
  Speaker 1: your weight does drop to zero. Oh interesting, interesting teaser.
• 27:30
  Speaker 1: So that we are, we're down, and we we dug
• 27:33
  Speaker 1: through the mantel, we swam through the molten outer core.
• 27:38
  Speaker 1: So here's here's where the tunnel idea would collapse, right,
• 27:41
  Speaker 1: because you couldn't. It's like it's liquid black Man down there, right, Yeah,
• 27:45
  Speaker 1: it's totally liquid metal. So you can't just dig a tunnel, right,
• 27:48
  Speaker 1: It's like digging a tunnel through the ocean. Right, something
• 27:51
  Speaker 1: to support it, and that's something would have to be
• 27:53
  Speaker 1: super strong and resistant to to heat. So I don't
• 27:55
  Speaker 1: even know what you could make it out of. You
• 27:57
  Speaker 1: have to be like a diamond diamonds earth ship, yeah,
• 28:01
  Speaker 1: something like something like that. You have to construct a
• 28:03
  Speaker 1: diamond tunnel as you go or something. I mean, this
• 28:06
  Speaker 1: is already implausible, but it sounds possible. But they did
• 28:10
  Speaker 1: it in movies. What do you mean that was in Minecraft?
• 28:15
  Speaker 1: You can dig to the center of the earth, so obviously.
• 28:19
  Speaker 1: Uh so there, Let's say you're you're swimming through this
• 28:22
  Speaker 1: magma for another two thousand kilometers and then then you'll
• 28:25
  Speaker 1: hit You'll hit it like a surface, right, if you
• 28:28
  Speaker 1: keep going down to the center. Yeah, you hit a surface, right,
• 28:31
  Speaker 1: and um, what you hit is this this solid inner
• 28:34
  Speaker 1: core which is mostly iron and nickel, And it's basically
• 28:37
  Speaker 1: just a huge ball of metal, right, And you might
• 28:42
  Speaker 1: ask like why is it solid? Right? It's solid because
• 28:44
  Speaker 1: of all the incredible pressure it's squeezing it down, right,
• 28:48
  Speaker 1: And and it's also it's interesting to me that it's
• 28:51
  Speaker 1: almost the size of the moon. It's like three the
• 28:55
  Speaker 1: size of the moon. Is this just like ball of
• 28:57
  Speaker 1: metal in the center of the earth? Huh? Way, why
• 29:01
  Speaker 1: is it metal? Why isn't it like like at some
• 29:03
  Speaker 1: point rocks, if you put them under pressure, they'll melt
• 29:07
  Speaker 1: into magma. But at something if you keep pressing them,
• 29:09
  Speaker 1: they'll actually solidify. Yeah, exactly, they'll solidify. And you know,
• 29:14
  Speaker 1: the Earth is cooling, right, the earth um was hot
• 29:17
  Speaker 1: and nasty when it was born, and it's been cooling
• 29:19
  Speaker 1: because space is cold, and eventually it's going to you know,
• 29:23
  Speaker 1: cool down even more. And so the center it's cooling
• 29:26
  Speaker 1: sort of from the center out, I guess you can imagine, right,
• 29:29
  Speaker 1: like the center is um it's getting solid, and this
• 29:32
  Speaker 1: solid in your core is growing right as the liquid
• 29:36
  Speaker 1: liquid part is sort of falling, the falling to the
• 29:39
  Speaker 1: center and and it's growing by I think like a
• 29:41
  Speaker 1: millimeter or two every year. Wow, so we got time.
• 29:48
  Speaker 1: We got time before Earth freezes over, is what you're
• 29:51
  Speaker 1: saying exactly Exactly, You've got time to finish that novel
• 29:55
  Speaker 1: you've been working on or whatever before the core of
• 29:57
  Speaker 1: the Earth solidifies. But it's important because then it's sort
• 30:00
  Speaker 1: of game over for life on Earth, right, because then
• 30:02
  Speaker 1: we wouldn't have a magnetic field. Yes, we need a
• 30:05
  Speaker 1: magnetic field to survive, because without a magnetic field, we
• 30:08
  Speaker 1: wouldn't be protected from space weather and space radiation and
• 30:11
  Speaker 1: stuff like that. Um. But you know it's going to
• 30:13
  Speaker 1: be the long time before the magnetic field stops because
• 30:16
  Speaker 1: the center of the Earth freezes. Um. But you know
• 30:18
  Speaker 1: it has happened, like on Mars. We think Mars used
• 30:21
  Speaker 1: to have the magnetic field. We think it used to
• 30:22
  Speaker 1: have all sorts of interesting stuff going on inside, but
• 30:25
  Speaker 1: now it's basically just a dead rock, right, and it
• 30:29
  Speaker 1: doesn't have a magnetic field anymore. And we don't think
• 30:31
  Speaker 1: it has a whole lot of stuff going on in
• 30:32
  Speaker 1: the inside though you know we're not. Um, wow, but yeah,
• 30:37
  Speaker 1: that could be the future of the Earth. But you know,
• 30:39
  Speaker 1: but then maybe we will have left the Earth and
• 30:41
  Speaker 1: explore the universe or developed ways to make artificial magnetic
• 30:45
  Speaker 1: fields or something else. Crazy, all right, So that's that's
• 30:47
  Speaker 1: at the center of the Earth. It's a ball the
• 30:50
  Speaker 1: size of the moon made out of metal, really thick
• 30:53
  Speaker 1: and hot and and solid metal. And that's it. Is
• 30:57
  Speaker 1: it Is it like that all the way to the
• 30:59
  Speaker 1: very center of the Earth. We think so, yeah, we
• 31:01
  Speaker 1: think it's just one big ball of metal. And in fact,
• 31:03
  Speaker 1: some people for a while thought that maybe that ball
• 31:05
  Speaker 1: of metal was just one big crystal. Right, you know
• 31:08
  Speaker 1: how metals can form crystals, these like regular lattices of
• 31:11
  Speaker 1: atoms that lineup, and for wild people thought it might
• 31:15
  Speaker 1: just be like a huge crystal. But now they're not
• 31:17
  Speaker 1: so sure. They downgraded their diamond rating on the Earth.
• 31:23
  Speaker 1: That's right, And we have to go change our insurance
• 31:25
  Speaker 1: policy because the new appraisers said it wasn't worth as much. Hey,
• 31:30
  Speaker 1: we like it. We love the Earth. It doesn't matter.
• 31:32
  Speaker 1: I love you anyway, baby, So it's not worth as much.
• 31:35
  Speaker 1: I guess it's worth everything to me, man, it's our home. Um, yeah, exactly.
• 31:40
  Speaker 1: So that's the descent of the earth. But remember, you
• 31:42
  Speaker 1: know we haven't visited these places. All this stuff we've learned,
• 31:45
  Speaker 1: we've learned sort of indirectly. Yeah, that's the amazing thing, um.
• 31:49
  Speaker 1: And so let's let's get into that. But let's take
• 31:51
  Speaker 1: a quick break, all right. So now we're we're gonna
• 32:07
  Speaker 1: get to the question of of what happens if you
• 32:09
  Speaker 1: jump through all down through the middle of the earth? Um.
• 32:11
  Speaker 1: But first I really want to know how we know
• 32:13
  Speaker 1: all this stuff, Daniel, Like, if we if we haven't
• 32:16
  Speaker 1: been able to drill down that deep, how do we
• 32:19
  Speaker 1: know what's all the way down to the center of
• 32:21
  Speaker 1: the earth. It's really an impressive triumph of science, right,
• 32:24
  Speaker 1: science were desperate to of the answer to your question.
• 32:27
  Speaker 1: And sometimes you can't see directly like you'd love to write,
• 32:30
  Speaker 1: so you have to look indirectly, have to look for clues,
• 32:32
  Speaker 1: and we look for ways to figure out what's going
• 32:34
  Speaker 1: on inside and we have a whole bunch of them,
• 32:37
  Speaker 1: and then we try to make sure they'll tell us
• 32:38
  Speaker 1: the same story. And my favorite one is the way
• 32:42
  Speaker 1: we look at the inside of the earth is by
• 32:43
  Speaker 1: looking at the impact from earthquakes, and we use earthquakes
• 32:48
  Speaker 1: the way you might like tap on the wall of
• 32:50
  Speaker 1: your house to figure out like is it hollow? Is
• 32:53
  Speaker 1: there a stud there? You can tell sort of what's
• 32:55
  Speaker 1: behind the wall by listening to how the sound moves
• 32:59
  Speaker 1: through it. Oh, I've heard of that. Like if there's
• 33:01
  Speaker 1: an earthquake that happens in one part of the world,
• 33:04
  Speaker 1: then you check with everybody else around the world to
• 33:06
  Speaker 1: see how that wave propagated. That's right, because the wave
• 33:11
  Speaker 1: from the earthquake. Right, earthquakes are these huge events, and
• 33:14
  Speaker 1: they cause a shock wave through the earth, and that
• 33:16
  Speaker 1: shock wave travels at different speed through different kinds of stuff. Right,
• 33:20
  Speaker 1: so you can build a model and you can say,
• 33:22
  Speaker 1: all right, well, if the earth was all water, how
• 33:24
  Speaker 1: fast would the shock wave arrive in Hawaii or arrive
• 33:28
  Speaker 1: in Russia? If the worth if the earth was all
• 33:30
  Speaker 1: you know, rock, how how fast would it move? And
• 33:33
  Speaker 1: they bounced when they when it changes medium, right, like
• 33:36
  Speaker 1: a wave, some of some of some of the your
• 33:39
  Speaker 1: wave will bounce back if it if it goes from
• 33:41
  Speaker 1: like air to water, or one type of rock to
• 33:44
  Speaker 1: another type of rock. And so that's another way can
• 33:47
  Speaker 1: they can tell where where are these um transitions between
• 33:51
  Speaker 1: different kinds of earth are. Yeah, you get all sorts
• 33:55
  Speaker 1: of interesting reflections. Just like when light hits the window,
• 33:58
  Speaker 1: most of it goes through, but some of it ounces off. Right.
• 34:00
  Speaker 1: You can use a window sometimes like a mirror. In
• 34:03
  Speaker 1: the same way as you were saying. Every time a
• 34:04
  Speaker 1: wave goes through a transition, a boundary from one kind
• 34:07
  Speaker 1: of material to another, part of it reflects, so they
• 34:10
  Speaker 1: can see these reflections. That's how we know that there
• 34:13
  Speaker 1: really are transitions there is that. Every time there's an earthquake,
• 34:16
  Speaker 1: the wave travels around the mantle, but it also reflects
• 34:19
  Speaker 1: off the mantle interface with the core, and then sometimes
• 34:23
  Speaker 1: it goes even deeper and then it reflects off the
• 34:25
  Speaker 1: inner core. So we can tell that there really are
• 34:28
  Speaker 1: layers there from these reflections, and we can get estimates
• 34:31
  Speaker 1: for their density based on how fast they're moving. We
• 34:34
  Speaker 1: know that that that's what the Earth looks like because
• 34:37
  Speaker 1: if it was made in any other way, if it
• 34:39
  Speaker 1: looked like any other way inside, we would see these
• 34:42
  Speaker 1: waves come out differently. That's right. It's sort of like
• 34:45
  Speaker 1: a big ultrasound, right, you know the way ultrasound works
• 34:48
  Speaker 1: to see like a baby inside the mom without cutting
• 34:50
  Speaker 1: her open. Obviously, is it sends these tiny little shock
• 34:52
  Speaker 1: waves ultrasound meaning higher frequency than you can hear into
• 34:57
  Speaker 1: your body, and it listens to how they come back,
• 34:59
  Speaker 1: and based on the speed and etcetera, it tells where
• 35:03
  Speaker 1: the stuff is and where the stuff isn't. So basically,
• 35:05
  Speaker 1: earthquakes are a way to ultrasound the Earth. Those guys
• 35:09
  Speaker 1: are the only ones who celebrate when this an earthquake.
• 35:11
  Speaker 1: They're like, huge earthquake. We get a new picture of
• 35:14
  Speaker 1: the inside of the Earth. We get to tell the
• 35:16
  Speaker 1: Earth there's a boy or a girl, oh my god,
• 35:20
  Speaker 1: or neither. Yeah, And so that's really that's, um, the
• 35:25
  Speaker 1: primary way we know about it. And to do that
• 35:27
  Speaker 1: you have to build models, right, And so you say, well,
• 35:29
  Speaker 1: maybe the Earth the Earth is this, in which case
• 35:32
  Speaker 1: we would see the reflections looking at that, and then
• 35:34
  Speaker 1: you compare what you predict to what you observe in
• 35:36
  Speaker 1: the tweet and tune and this tells us a lot
• 35:39
  Speaker 1: about what we know about the inside of the Earth
• 35:41
  Speaker 1: without ever going there. Wow, that's pretty cool, got science, man, science,
• 35:46
  Speaker 1: you are awesome. Yeah, buy yourself a pizza, a real pizza,
• 35:51
  Speaker 1: not one with pineapples on it. And um, you know,
• 35:53
  Speaker 1: we have some direct evidence, like we have dug down
• 35:56
  Speaker 1: pretty far to see what the crust is made out of,
• 36:00
  Speaker 1: and um, you know, sometimes things do crack open and
• 36:03
  Speaker 1: magma comes out from the earth and turns into lava,
• 36:05
  Speaker 1: and we can sample that and see what it is, right,
• 36:08
  Speaker 1: And we can look at rock outcroppings, you know, places
• 36:11
  Speaker 1: where like the crust has been lifted up so we
• 36:13
  Speaker 1: could see what used to be underneath. Um, stuff like that. Wow,
• 36:17
  Speaker 1: But it's pretty amazing that basically the Earth is not
• 36:20
  Speaker 1: a big ball of rock, right, Like it's this kind
• 36:22
  Speaker 1: of active, moving, squishy, dynamic ball of stuff. Yeah. Yeah,
• 36:30
  Speaker 1: it's there's a lot of stuff going on, right, It's
• 36:31
  Speaker 1: not just a rock. If it was just a rock,
• 36:34
  Speaker 1: then life on Earth would be very different, maybe impossible,
• 36:36
  Speaker 1: right without the magnetic field to protect us in our atmosphere.
• 36:40
  Speaker 1: So we should be grateful that there's a huge engine
• 36:42
  Speaker 1: humming under our feet, that all this stuff is happening,
• 36:45
  Speaker 1: you know. And I wonder something I was trying to
• 36:47
  Speaker 1: figure out but couldn't is like when we first became
• 36:49
  Speaker 1: aware of this, you know, because as humans, you know,
• 36:52
  Speaker 1: we know we live on the surface, but like a thousand,
• 36:54
  Speaker 1: two thousand years ago, people must have had a very
• 36:57
  Speaker 1: primitive understanding of what the Earth was made out of. Well,
• 37:00
  Speaker 1: they probably thought what I talk which is just a
• 37:02
  Speaker 1: giant rock, right, yeah, And people I think, like more
• 37:06
  Speaker 1: than add years ago were able to make density measurements
• 37:09
  Speaker 1: of the Earth. Right, they know the size of the Earth.
• 37:11
  Speaker 1: They know basically know how big it is, and you
• 37:14
  Speaker 1: can figure out, you know, with the strength of the
• 37:16
  Speaker 1: gravitational force, and from that you can figure out what
• 37:18
  Speaker 1: the mass of the Earth is, and that tells you,
• 37:20
  Speaker 1: like what's the average density. So, like more than a
• 37:22
  Speaker 1: d years ago were able to measure the average density
• 37:25
  Speaker 1: of the Earth and discover that it was more dense
• 37:27
  Speaker 1: on average than it was in the surface, which suggested
• 37:30
  Speaker 1: that like something denser was going on under our feet.
• 37:33
  Speaker 1: But that was really the first clue. Wow, cool, all right,
• 37:41
  Speaker 1: So that's that's what the Earth is made out of.
• 37:43
  Speaker 1: It's a thin crust on top of a fluid rock,
• 37:47
  Speaker 1: on top of a giant layer of magma two thousand
• 37:52
  Speaker 1: kilometers thake uh. And then down to a little um
• 37:56
  Speaker 1: crystal diamond ball the size of the moon um iron nickel, right,
• 38:04
  Speaker 1: you can you can advertise it on the internet. It's
• 38:06
  Speaker 1: a crystal diamond, and then they'll be disappointed when you're
• 38:09
  Speaker 1: sending them just an iron nickel ball. But sure, go ahead,
• 38:12
  Speaker 1: we'll call it like an iPhone. You know, it's a
• 38:15
  Speaker 1: metallic nickel exactly, exactly right. So okay, let's say let's
• 38:21
  Speaker 1: get down then to what we set out to answer,
• 38:23
  Speaker 1: which is what would happen if you jump down a
• 38:26
  Speaker 1: hole through the earth. Well, we were already established it's
• 38:29
  Speaker 1: impossible to dig that hole. Yeah, so let's let's imagine
• 38:31
  Speaker 1: it's possible that aliens come and have some super digging
• 38:34
  Speaker 1: technology and some super tunnel technology, and we can actually
• 38:37
  Speaker 1: make that whole all the way through the earth and
• 38:40
  Speaker 1: out the other side, right through the very center and
• 38:42
  Speaker 1: hold it open, because you know, the magma wants to
• 38:45
  Speaker 1: flow in, the liquid rock wants to crush it in,
• 38:49
  Speaker 1: and that that corn middle doesn't really um it's so
• 38:54
  Speaker 1: dense it doesn't want to get drilled through, right, yeah, exactly.
• 38:57
  Speaker 1: So you need a lot of legal paperwork before you
• 38:59
  Speaker 1: can jump into this hole. But let's assume that we
• 39:02
  Speaker 1: figured out all the physics and all the law aspects
• 39:04
  Speaker 1: of it, and that we're ready to jump. Right before
• 39:07
  Speaker 1: we do that, we want to do some science. Okay,
• 39:09
  Speaker 1: so there's a whole there's a tunnel going through the
• 39:11
  Speaker 1: center of the Earth out to the other side. Okay,
• 39:14
  Speaker 1: and what happened? What what what happens to be jump into? Yeah,
• 39:17
  Speaker 1: So that it's really fascinating because you have to think
• 39:19
  Speaker 1: about the force of gravity. So you're on the surface
• 39:21
  Speaker 1: of the Earth. The whole earth is pulling you towards
• 39:25
  Speaker 1: the center of the earth. Right, because the whole Earth
• 39:27
  Speaker 1: is a smaller radius than you do. Right, every little
• 39:30
  Speaker 1: bit of it is pulling it. But you can think
• 39:32
  Speaker 1: about you can treat it gravitationally as if it was
• 39:35
  Speaker 1: just like a particle at the center of the Earth
• 39:38
  Speaker 1: that was pulling on you because it's all under your feet.
• 39:41
  Speaker 1: But once you jump into that hole, then some parts
• 39:45
  Speaker 1: of the Earth are no longer on the inside. Some
• 39:48
  Speaker 1: of them are like on the outside. So imagine you're
• 39:50
  Speaker 1: like halfway down this hole. Like let's say you're a
• 39:53
  Speaker 1: kilometer down falling eating your snack. Now there's a whole
• 39:58
  Speaker 1: bunch of earth Earth above you that's now pulling you back. Right. Actually,
• 40:02
  Speaker 1: the earth above you on average doesn't have any effect
• 40:05
  Speaker 1: on you. There's the one that the stuff that's just
• 40:09
  Speaker 1: above you, Yeah, that's pulling on you. But there's like
• 40:11
  Speaker 1: this kilometer thick shell of Earth, right, and the stuff
• 40:15
  Speaker 1: that's on the other side is pulling on you, and
• 40:17
  Speaker 1: the stuff that's above you is pulling on you. It
• 40:18
  Speaker 1: all cancels out. So if you're inside a shell, then
• 40:23
  Speaker 1: all the gravitational forces cancel out. What yeah, yeah, I mean, imagine,
• 40:29
  Speaker 1: for example, what happens when you get to the center, right,
• 40:31
  Speaker 1: What happens when you get to the center. Is there
• 40:33
  Speaker 1: any gravity there? No, because every point, every little bit
• 40:36
  Speaker 1: of the Earth is pulling you equally in all directions, exactly.
• 40:40
  Speaker 1: And that's true for any shell that you're on the
• 40:43
  Speaker 1: inside of. So if you're halfway down the Earth, then
• 40:46
  Speaker 1: you only feel the gravitational force of the part of
• 40:49
  Speaker 1: the Earth that's closer to the center than you are,
• 40:52
  Speaker 1: right a sphere of that radius. The stuff that's above you,
• 40:55
  Speaker 1: you don't feel like Let's say we're digging the tunnel
• 40:58
  Speaker 1: and we only get halfway there and we stop and
• 41:02
  Speaker 1: we stand there on the bottom of that hole. You're saying,
• 41:05
  Speaker 1: I would weigh half as much like I could jump.
• 41:07
  Speaker 1: It would feel like it we're standing on the moon
• 41:09
  Speaker 1: as you're digging down, you would you would start to
• 41:12
  Speaker 1: feel weightless, Yes, exactly. So as you so you jump
• 41:15
  Speaker 1: into this hole, right, and just before you jump, you're
• 41:18
  Speaker 1: feeling the full gravitational force of the Earth. And as
• 41:20
  Speaker 1: you go down, the gravitational force starts to go down,
• 41:23
  Speaker 1: and it goes down linearly, so that when you get
• 41:26
  Speaker 1: to zero, when you get to the center, there's no
• 41:28
  Speaker 1: force on you anymore, which makes sense, as you were saying,
• 41:30
  Speaker 1: because you're pulled in every direction. Wow. So if you open,
• 41:33
  Speaker 1: like if you drill drill through, you're falling through and
• 41:36
  Speaker 1: you get to the center and you would be floating
• 41:39
  Speaker 1: around in space just like no, because you'd have you'd
• 41:42
  Speaker 1: have a huge velocity, right, you'd have to have been
• 41:45
  Speaker 1: pulled down from a bunch of stuff, so you have
• 41:47
  Speaker 1: a huge amount of velocity and you shoot right through
• 41:49
  Speaker 1: the center. Right, the center would be your highest speed.
• 41:52
  Speaker 1: It's like on a roller coaster. You start at the
• 41:54
  Speaker 1: top right and it rolls you down a hill. The
• 41:56
  Speaker 1: bottom of the hill right, then you're going really really fast.
• 42:00
  Speaker 1: If there's no friction, you would just keep going, yeah,
• 42:02
  Speaker 1: because you've been falling all this time, exactly. Unless it's
• 42:05
  Speaker 1: like a party down there and people hanging out and
• 42:07
  Speaker 1: ready to catch you. You just shoot right through the
• 42:09
  Speaker 1: center of the earth, and then gravity would start to
• 42:12
  Speaker 1: slow you down again on your way through the other
• 42:14
  Speaker 1: side of the tunnel. Right, it would stake. Now now
• 42:18
  Speaker 1: it's pulling you back, polling you back, it's slowing you down,
• 42:22
  Speaker 1: and it's just enough gravity to slow you down so
• 42:25
  Speaker 1: that you would emerge from the tunnel on the other
• 42:27
  Speaker 1: side and then just stop with the same speed that
• 42:30
  Speaker 1: you had just when when you jumped in. Yeah, which
• 42:33
  Speaker 1: is zero, right, So I'm assuming that the tunnel on
• 42:36
  Speaker 1: the other side comes out of exactly the same elevation, right.
• 42:39
  Speaker 1: If you then you would come right out of the
• 42:42
  Speaker 1: tunnel and you just sort of like hover right above
• 42:44
  Speaker 1: the tunnel for a second before falling back down again.
• 42:47
  Speaker 1: And if you didn't do anything, you would just sort
• 42:48
  Speaker 1: of go back and forth, oscillating back and forth through
• 42:51
  Speaker 1: the earth forever, up and down, up and down. Have
• 42:55
  Speaker 1: you calculated how long would take you to do that
• 42:57
  Speaker 1: take that trip? I have not done that calculation. Actually
• 43:00
  Speaker 1: leave it as homework for the listener. But you have
• 43:02
  Speaker 1: to be careful because if you jump, if your elevation,
• 43:05
  Speaker 1: your distance from the center of the Earth when you
• 43:07
  Speaker 1: jump is um less than the elevation where you're going
• 43:11
  Speaker 1: to come out on the other side, and you're not
• 43:13
  Speaker 1: gonna make it, right, if you start on the Death
• 43:16
  Speaker 1: Valley and you want to come out the amount everest,
• 43:18
  Speaker 1: and you're not gonna make it to the top amount everest, right,
• 43:21
  Speaker 1: You're just gonna fall back down into the hole. Yeah, exactly, exactly.
• 43:25
  Speaker 1: But if the Earth was a perfect sphere and you
• 43:27
  Speaker 1: jumped onto one side, then you come out the other
• 43:29
  Speaker 1: side of exactly the same height above the surface. But
• 43:31
  Speaker 1: if you slow yourself down and you stopped at the core,
• 43:35
  Speaker 1: then you would be waitless and you'd be floating there. Yeah, exactly,
• 43:38
  Speaker 1: because the earth gravity would be pulling on you from
• 43:40
  Speaker 1: every direction simultaneously, which is like having no gravity. Wow.
• 43:44
  Speaker 1: And that would be a pretty awesome moment, right, and
• 43:46
  Speaker 1: be like at the center of the Earth, the entire
• 43:48
  Speaker 1: Earth around you. Right. Yeah, I hope you're not clustrophobic.
• 43:52
  Speaker 1: It would be pretty hard to climb back out, right,
• 43:54
  Speaker 1: that's kind of the problem. Yeah, that would be a
• 43:56
  Speaker 1: very long climb. Oh my gosh, Wow, I hope somebody
• 43:59
  Speaker 1: built a live are h all right? Well? That that
• 44:03
  Speaker 1: that's um that's what the Earth is made out of.
• 44:06
  Speaker 1: And if you dropped a pizza down a hold that
• 44:09
  Speaker 1: goes through the center of Earth, they would just come
• 44:11
  Speaker 1: right back to you, right eventually. Yeah, Or you could
• 44:15
  Speaker 1: deliver pizza to the other side of the Earth just
• 44:17
  Speaker 1: by dropping through that hole and it would just like
• 44:19
  Speaker 1: come on out the other side and float there for
• 44:20
  Speaker 1: a second while they're somebody would grab It's a totally
• 44:24
  Speaker 1: realistic way. I bet Elon Musk is working on that
• 44:26
  Speaker 1: pizzas and the bonuses. It would be warm because it
• 44:31
  Speaker 1: would heat up on the way you could you could
• 44:33
  Speaker 1: dump it in frozen and it would come out nice
• 44:35
  Speaker 1: and coasting. This is a great business opportunity. I hope
• 44:39
  Speaker 1: the lawyers are scribbling this down as you're talking. All right, Well,
• 44:43
  Speaker 1: thanks for joining us. I hope that, um, that wasn't
• 44:46
  Speaker 1: too hardcore for you guys out there. I hope we
• 44:48
  Speaker 1: didn't get too crusty on you. All right, Thanks for
• 44:50
  Speaker 1: joining us, See you next time. Thanks for tuning in.
• 45:01
  Speaker 1: If you still have a question after listening to all
• 45:03
  Speaker 1: these explanations, please drop us a line. We'd love to
• 45:06
  Speaker 1: hear from you. You can find us at Facebook, Twitter,
• 45:09
  Speaker 1: and Instagram at Daniel and Jorge that's one word, or
• 45:13
  Speaker 1: email us at feedback at Daniel and Jorge dot com.
• 45:17
  Speaker 1: Thanks for listening and remember that Daniel and Jorge Explain
• 45:20
  Speaker 1: the Universe is a production of I Heart Radio from
• 45:23
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• 45:26
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• 45:29
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