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Speaker 1: Welcome to Stuff from the Science Lab from how stuff

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Speaker 1: works dot com. You guys, welcome to the podcast. This

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Speaker 1: is Alison. I don't know if the science editor at

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Speaker 1: how stuff works dot com. And there is Robert Lamb,

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Speaker 1: science writer and how stuff works dot com. So, Alison,

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Speaker 1: have you seen the movie Phantasm? I've not seen it.

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Speaker 1: It's a nineteen seventies flick, right, yeah, harror flick. You

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Speaker 1: haven't seen it. I have not, but you've mentioned it before, right, Well, okay,

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Speaker 1: it's awesome. It's um. I mean it's it's horrible, but

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Speaker 1: it's awesome. It's um. The basic plot line here is

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Speaker 1: you have a mortuary where some funny things are happening.

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Speaker 1: There silver balls flying around, stabbing people in the head. Uh.

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Speaker 1: And there are these dwarves running around in these little

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Speaker 1: like I think they're yellow, little yellow robes, okay, like

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Speaker 1: evil dwarves. Right, And you come to find out that

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Speaker 1: all of this basically has to do with gravity. There's

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Speaker 1: a really tall man, like a scary old man. It's

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Speaker 1: really tall, Okay. And it turns out he's from another

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Speaker 1: planet where the gravity is more intense, like a larger world. Okay,

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Speaker 1: so that's why he's taller when he comes to this world, okay,

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Speaker 1: and the deal with the dwarves, he's taking corpses and

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Speaker 1: smushing them down, making a more compact and bringing him

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Speaker 1: back to life a zombies and then sending them to

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Speaker 1: this other world to be like slaves. All right, So

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Speaker 1: dwarves are being used as as as zombies. Dwarves are

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Speaker 1: being used as slave labor on another world where there's

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Speaker 1: more gravity. And so this all occurs thanks to gravity. Yes,

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Speaker 1: like it Like for me anyway, as as a kid.

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Speaker 1: You know, it's like, you know, gravity is, They're great,

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Speaker 1: but I never think about it. But then somebody comes

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Speaker 1: along and shows me how gravity is affect you know,

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Speaker 1: zombie dwarves and uh and it it really you know,

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Speaker 1: unders it really resonated with me and underlining how amazing

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Speaker 1: gravity is. I mean, um, like I said, we take

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Speaker 1: it for granted because it's everywhere, because every pretty much

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Speaker 1: every physical act on the planet um involves gravity in

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Speaker 1: somewhere and within another. So that's what we're going to

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Speaker 1: talk about the day. We're gonna We're gonna basically talk

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Speaker 1: about four examples um of technologies that utilize gravity in

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Speaker 1: a way that highlight just how amazing it is. But

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Speaker 1: of course to do that, we need to talk briefly

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Speaker 1: about about gravity itself. Now, we have an excellent article

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Speaker 1: on how Stuff Works dot Com about this um and

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Speaker 1: I recommend checking that out if you want more details.

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Speaker 1: But basically, two schools of thought. There's there's Newton Newton's

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Speaker 1: uh a theory of universal gravitation from back in the

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Speaker 1: sixt eighties, and this is the idea. The gravity is

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Speaker 1: a predictable force that acts on all matter in the universe,

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Speaker 1: and it's a function of both mass and distance. Right. Basically,

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Speaker 1: each particle of matter attracts every other particle of matter,

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Speaker 1: all right. Whether we're talking about a great or a

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Speaker 1: massive sign. Okay, whether we're talking about a spaceship or

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Speaker 1: I don't know, a dog, everything has gravity, all right.

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Speaker 1: And if ever, and if the only two things you

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Speaker 1: had in the universe were a dog and a spaceship,

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Speaker 1: they would each have a great gravitational pull and it

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Speaker 1: would be drawn to each other. Okay, um, go ahead.

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Speaker 1: And then along comes Einstein. Yes, along comes Einstein, and

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Speaker 1: he says, fooie to this whole dog and spaceship business.

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Speaker 1: And he says that, he says that gravity isn't even

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Speaker 1: a force, all right, he's a he's seeing it more

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Speaker 1: as a distortion in the shape of space time, all right,

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Speaker 1: as the you know, a distortion in the fourth dimension.

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Speaker 1: And in Einstein's footsteps. You have some more modern theories

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Speaker 1: as well, okay, that are less even even less proven.

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Speaker 1: There's the idea that UM that gravity is due to

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Speaker 1: little particles called gravitons that that cause objects to be

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Speaker 1: attracted to one another. And there's another theory that there's

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Speaker 1: gravitational radiation UM, which which is supposedly the ideas that

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Speaker 1: gravitational radiation is generated when an object is accelerated by

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Speaker 1: the external force. Basically, the idea here is that gravity

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Speaker 1: is is awesome and every day it's mysterious. Um. Basically,

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Speaker 1: the idea here that it is that as every day

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Speaker 1: as gravity is, there's a lot we don't know. There's

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Speaker 1: a lot we don't know about it. It's still kind

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Speaker 1: of a mystery in many ways. All right. So with that,

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Speaker 1: let's kick off with four cool things that gravity can

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Speaker 1: do for you. Yeah, what do you got? What can

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Speaker 1: gravity do for you? Well, if you listen to our

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Speaker 1: Fighting Asteroids podcast, we touched on this briefly but gravity

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Speaker 1: can actually I could save the Earth from being destroyed

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Speaker 1: by some crazy space rock and always good. Yeah, I

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Speaker 1: like this. Um, So this thing called a gravity tractor,

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Speaker 1: and I'm not talking about the the grateful dead cover

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Speaker 1: band that seems to be located in upstate New York

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Speaker 1: of the same name. This gravity tractor, actually, um might

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Speaker 1: have a might have a chance of being built. According

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Speaker 1: to the BBC, there's this British company by the name

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Speaker 1: of E. A. D. S Astrium that they finally started

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Speaker 1: taking concrete steps to make the graph tractor reality. So

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Speaker 1: it's the graph tractor gonna do it well. It's a

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Speaker 1: robotic spacecraft weighing roughly ten tons or so, and it

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Speaker 1: has a has a particularly daunting task. Once it's launched

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Speaker 1: into space, it has to get within forty eight m

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Speaker 1: so roughly a hundred fifty feet of the space rocking question.

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Speaker 1: And once it gets within that range, it has to

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Speaker 1: pull the rock toward it, and the two of them

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Speaker 1: march happily off on a path that's not kind of

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Speaker 1: coincide with the Earth and now in theory though it

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Speaker 1: could also if you had a New York area jam

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Speaker 1: band floating in space. It could also use its immense

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Speaker 1: gravity to to pull them aside as well. Right right,

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Speaker 1: and I think if you pull the string cheese incident

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Speaker 1: on there, I mean it could just do crazy winners

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Speaker 1: with a space rocks headed our way. Um. And the

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Speaker 1: other chicky thing about the tractors, it's gonna we have

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Speaker 1: to launched. The other chicky thing about the tractors that

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Speaker 1: has to be launched fifteen years ahead of time. So

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Speaker 1: we're kind of we're kind of stuck. This is what

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Speaker 1: we're relying on right now. So gravity, it can it

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Speaker 1: can save you from a space rock someday. Perhaps what

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Speaker 1: else can it do out in space? Well, gravity can

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Speaker 1: also help you fire a spaceship to some distant corner

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Speaker 1: of the Solar System. I like the way that sounds. Yeah,

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Speaker 1: this is something we call gravity assist. Sometimes you see

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Speaker 1: it referred to as a gravity slingshot, but that's a

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Speaker 1: little misleading. Um, so just think of it. It's gravity assist,

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Speaker 1: all right. And to understand that, you need to think

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Speaker 1: of the Solar System in terms of the Sun's gravity. Well, okay,

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Speaker 1: imagine a bathtub, all right, It's filled with water and

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Speaker 1: it has a little boat in it. Okay, you pull

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Speaker 1: the drain, the water begins to to to go to

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Speaker 1: to leave the bathtub in the form of a whirlpool.

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Speaker 1: The little boat is going to be pulled towards the whirlpool,

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Speaker 1: all right. In the scenario, the Sun is the whirlpool.

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Speaker 1: It's the object of the most mass and if it

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Speaker 1: has the most gravitational pool and spacecraft, right, and it's

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Speaker 1: gonna if it's if the little toy boat is moving

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Speaker 1: towards the world pool, it's gonna go faster to move

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Speaker 1: away from the world pool. It has to work harder

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Speaker 1: and it's going slower. Okay, that's basically the gravity well.

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Speaker 1: So if we want to send something farther out into

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Speaker 1: the gravity well, out to one of the outer planets, um,

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Speaker 1: we need to we need a little help, all right,

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Speaker 1: and and it and it uh, it's more effective if

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Speaker 1: we don't have to depend on say, you know, thrusters

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Speaker 1: and rockets to do all of the work and take

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Speaker 1: a take advantage of inherent force. Right. So that's where

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Speaker 1: the gravity assist comes in. And this is a fly

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Speaker 1: by technique where we can add or subtract momentum to

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Speaker 1: increase or discrete decrease the energy of a spacecraft. Orbit,

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Speaker 1: so we've used it. Yes, UM. Take, for for example,

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Speaker 1: Voyager two launched in um, we flew it by Jupiter.

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Speaker 1: Will first, just you know, to see Jupiter, that was

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Speaker 1: one of its mission objectives. But also um, by flying

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Speaker 1: flying by Jupiter, this provided traject trajectory boost to shoot

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Speaker 1: it towards Saturn. Now again go back and going back

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Speaker 1: to the spaceship and the dog. You know, both both

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Speaker 1: the spaceship and the dog have mass and therefore have

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Speaker 1: their own gravitational pool. Right, So Voyager two has its

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Speaker 1: own gravitational pool, as does Jupiter. All right. So when

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Speaker 1: the spacecraft actually tugs on Jupiter as it goes past,

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Speaker 1: all right, and actually decreases the planet's orbital momentum by

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Speaker 1: a tiny amount, very tiny amount. In return, the spacecraft

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Speaker 1: acquires momentum from Jupiter. Except as we're talking, a significant

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Speaker 1: amount of momentum, and uh, and it it shoots it

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Speaker 1: off in this new trajectory. Okay. Uh. One of the

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Speaker 1: more useful analogies, uh that that you find for this

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Speaker 1: is imagine a kid standing next to um a train track, okay,

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Speaker 1: and he has a softball in his hand. The softball

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Speaker 1: is a spacecraft, all right, And then hurtling down the

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Speaker 1: train track is a locomotive, al right. The locomotive is Jupiter.

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Speaker 1: If you were to throw the softball and hit the

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Speaker 1: front of the coming train, then the softball would would

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Speaker 1: veer off into another direction with the momentum of the train.

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Speaker 1: So it's it's very useful for for shooting off any

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Speaker 1: number of probes UH into into the surrounding Solar system

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Speaker 1: and uh A lot of people have even looked at

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Speaker 1: considered possibilities of using it for the future use of

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Speaker 1: man space spacecraft being able to like use the the

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Speaker 1: Sun's gravity to shoot an aircraft off to a not

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Speaker 1: an aircraft, of using the Sun's gravitational poole to um

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Speaker 1: to shoot a spaceship off towards another system. Have you've

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Speaker 1: seen Star Trek or any number of science fiction properties,

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Speaker 1: then you've you've you've heard examples of this, So I'd

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Speaker 1: say that's a cool thing. Gravity shooting you to a

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Speaker 1: distant corner of the galaxy. On a more earthly level,

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Speaker 1: gravity can perhaps let your home someday. And this is

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Speaker 1: an idea that's been around for quite a while. Back

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Speaker 1: in the nineteen seventies, there are a bunch of fellows

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Speaker 1: at the Lawrence Livermore lab who thought we should try

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Speaker 1: to harness the energy potential of gravity courtesy of black hole.

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Speaker 1: So this is what they had in mind. You guys,

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Speaker 1: remember that a black hole forms when this big old

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Speaker 1: star is dying and it's collapsing inward, and the end

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Speaker 1: result is this tiny object that's just unspeakably dense. So

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Speaker 1: the gravitational force of a black hole is large, so

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Speaker 1: large that not even light can escape it. I know

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Speaker 1: you guys know this, but let's just reiterate it. So

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Speaker 1: the idea was, according to these scientists, was well, let's

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Speaker 1: locate a black hole, well, get it to orbit the Earth.

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Speaker 1: That's now that that's the point I think where you

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Speaker 1: just you cancel this plan like that just sounds like

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Speaker 1: the worst idea ever. Hey, let me just okay, it

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Speaker 1: gets better, Okay, Okay. So you're gonna get the said

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Speaker 1: black hole to orbit the Earth with the help of

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Speaker 1: a spaceship, and once it's in permanent orbit, just you know,

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Speaker 1: kind of hanging out like black hole does, you're gonna

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Speaker 1: tap the power of said black hole by firing matter

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Speaker 1: into it. Okay. So the whole plan is we're going

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Speaker 1: to go and find the most destructive force in the universe.

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Speaker 1: We're going to bring it home and then we're going

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Speaker 1: to feed it. Yes, yes, and then wait, it gets better.

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Speaker 1: So you know that things get really tiny, as are

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Speaker 1: you know, hurtling towards their on their death spiral towards

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Speaker 1: a black hole. Well, all that getting tiny business generates

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Speaker 1: an amounse amount of energy, and they thought that this

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Speaker 1: amount of energy could in fact be enough to start

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Speaker 1: a fusion reaction. So this one, this idea of a

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Speaker 1: black hole gravity thing, actually never came to fruition. I

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Speaker 1: think probably the the first point of business was moving

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Speaker 1: the black hole, or actually maybe even locating black hole

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Speaker 1: and then moving black hole. So a couple of a

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Speaker 1: couple of a couple of holes in this plan. Yes,

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Speaker 1: the latest incarnation of gravity power is a lamp. It's

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Speaker 1: a little bit simpler and a black hole. No no, no, no, um.

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Speaker 1: Let me explain. It's conceived of by this grad student

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Speaker 1: at Virginia Tech, and I think he entered his invention

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Speaker 1: in some sort of TEO thousand in a green Tech award.

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Speaker 1: And it's a guy by the name of claymont. Well.

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Speaker 1: Clay calls his lamp the gravity So conceptually, here's how

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Speaker 1: Clay's gravity powered lamp works. If you picture kind of

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Speaker 1: a cylinder shaped floor lamp, maybe about five feet tall. Um,

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Speaker 1: Now imagine that there are these like five ten pound

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Speaker 1: brass swats sitting there at the top. And for those

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Speaker 1: of you guys who don't know what one is, there's

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Speaker 1: a ball screw in in the in the floor lamp.

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Speaker 1: And what is the what is ball screw? I had

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Speaker 1: no idea before I started doing this podcast. Well, it's

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Speaker 1: a it's a linear screw and um, something rotates downward

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Speaker 1: on it. So it's kind of like falling on the

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Speaker 1: ball screw. It's moving downward on the ball screw. And

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Speaker 1: as these brass weades moved downward on the ball screw,

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Speaker 1: the screw rotates, and that rotational motion is able to

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Speaker 1: spin a generator and convert the motion into electricity. So

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Speaker 1: if you can't quite picture, you can always check out

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Speaker 1: the illustration. We have a good one on our how

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Speaker 1: gravity powered lamps were an article. So anyway, this electricity

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Speaker 1: powers ten led bulbs which light up and whaila you

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Speaker 1: have light. And do you think, well, how long is

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Speaker 1: that going to take? Because gravity can happen relatively fast right,

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Speaker 1: falling objects might be down to the bottom and lamp,

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Speaker 1: but actually it takes four hours, so that would be

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Speaker 1: a good amount of light. Would it would work faster

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Speaker 1: on the the phantasm planet with the dwarves? Sure would, Surewood.

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Speaker 1: It's also worth noting here that the hour glass is

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Speaker 1: actually a gravity powered timetelling device. Yeah, and it seems

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Speaker 1: like a little bit of a simple concept than the

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Speaker 1: The gravity powered lamp also cuckoo clocks, but are also

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Speaker 1: worth considering that they're actually powered by black holes. So anyway,

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Speaker 1: the thing with Poort Clay's lamp is that the d

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Speaker 1: technology isn't quite where it needs to be, and the

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Speaker 1: LEDs aren't as efficient as they need to be, and

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Speaker 1: so that means the weights would have to be much heavier.

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Speaker 1: And that's about where we are with the gravity powered lamp.

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Speaker 1: So you cannot buy one at your local lamp star.

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Speaker 1: It sounds promising, though, I like the idea of gravity

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Speaker 1: powered electronics. Well, I'll tell you another thing that gravity

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Speaker 1: can do for us. What gravity can help us understand

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Speaker 1: what's going on underneath the Earth surface. And how many

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Speaker 1: do that? Well, think of it this way. Imagine an

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Speaker 1: appetizer sampler platter. All right, you know it's it's covered

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Speaker 1: with fried cheese sticks, hush puppies. What are the what's

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Speaker 1: the meat on the stick called? Oh, chicken settee? Chicken

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Speaker 1: sette all right, all of idea of different foods. Now,

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Speaker 1: something late and fluffy too, right? Yeah? Like, well, hush

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Speaker 1: puppies are lighting fluffy? Right? Well, what's something light and

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Speaker 1: fluffy do you get as an appetizer? Um, we'll see.

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Speaker 1: I think that's the thing. Most appetizers, they're so hideously

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Speaker 1: unhealthy that you get them in small portions first, right, okay,

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Speaker 1: So imagine something light and fluffy appetizer, but hush puppy.

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Speaker 1: So so you have all these different items on the plate, right,

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Speaker 1: and all of them have different densities, okay, which means

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Speaker 1: and all of them have gravitational pools, all right, And

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Speaker 1: the more dense the appetizer item, the more gravitational pool

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Speaker 1: it has. Okay, Okay, all right, Well, our planet is

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Speaker 1: basically an appetizer platter when it comes to gravity. All right,

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Speaker 1: there are our planet has is covered with varying densities

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Speaker 1: of rock. Um, you have you have water that's cold,

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Speaker 1: you have water that's hot, and of course there's different

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Speaker 1: tensity there. Um. You know, you look under the Earth,

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Speaker 1: they're gonna be they're gonna be empty caverns, they're going

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Speaker 1: to be uh, you know, blocks of solid bedrock. There's

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Speaker 1: going to be you know, liquid magma. So gravity is

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Speaker 1: gonna vary according to where are you on there. That's

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Speaker 1: interesting because I guess I just think of it as

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Speaker 1: such a constant uniform Yeah. Yeah, we think of it

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Speaker 1: more as uh, you know, a pizza with a pizza's

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Speaker 1: worth of you know, of a uniform gravitational pool. But

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Speaker 1: like if you go up to Hudson Bay in Canada, Um,

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Speaker 1: the gravity is actually less there. And I need to

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Speaker 1: stress that it's not not less in the sense that

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Speaker 1: that you can go to, uh to Hudson Bay and

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Speaker 1: uh and feel like you lost weight. It's right, You're

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Speaker 1: not gonna be able to fit in your skinny jeans,

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Speaker 1: are right. The Earth's gravity is still pretty uniform, um,

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Speaker 1: all all across the globe, but it varies um to

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Speaker 1: it to a slight degree um wherever you go. All right,

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Speaker 1: So um, you know, most people say, well, what does

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Speaker 1: what does that matter? Right? It matters when you start

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Speaker 1: looking into fluid dynamics, alright. The ocean, for instance, Um,

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Speaker 1: you have it dictates the flow of hot and cold water,

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Speaker 1: all right. I think of it as a topography, okay,

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Speaker 1: Like if you have a hill next to a plane,

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Speaker 1: you know water is gonna flow down that hill. All right.

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Speaker 1: Well you have the same kind of topography going on

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Speaker 1: across the planet, except in terms of gravity, with fluids

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Speaker 1: drawn towards the areas of higher gravity. Okay. So we're

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Speaker 1: very interested in finding out exactly what this uh, this

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Speaker 1: secret topography looks like. We in fact, we've launched to

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Speaker 1: um Um orbiting a spacecraft. There's a European Space Agencies

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Speaker 1: Gravity Field and Steady State Ocean Circulation Explore and this

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Speaker 1: is up there right now, um, yes, called GHOS. See

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Speaker 1: that one went up in two thousand nine. And then

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Speaker 1: there's NASA's Gravity Recovery and Climate experiment that's called Race

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Speaker 1: and Grace went up in two thousand two. All right, ghost.

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Speaker 1: These mission has been to take a picture of what

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Speaker 1: this uh, the secret topography of gravity, which we call

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Speaker 1: the geode, to take a picture of what that looks

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Speaker 1: like right at nay moment of time, Like what are

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Speaker 1: the highs, what are the lows? Uh? Grace has been

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Speaker 1: looking at how the geo changes, because it's always changing too.

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Speaker 1: It's not like like you can you know, you'll be

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Speaker 1: able to go here, and oh, the gravity is always

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Speaker 1: going to be this, especially when it comes to the ocean.

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Speaker 1: And why do we care if the geo changes? Because

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Speaker 1: the more we understand how the ocean transports heat and water,

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Speaker 1: the more we understand how the ocean moves, And the

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Speaker 1: more we understand how the ocean moves, the more we

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Speaker 1: understand how the atmosphere moves. See, it's all a part

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Speaker 1: of Earth's outer layer of fluid, all right, and that

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Speaker 1: is where our weather takes place. UM and uh and

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Speaker 1: you know everything from from fierce hurricanes, two patterns of

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Speaker 1: drought and uh floods and what have you? All right, UM,

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Speaker 1: so it helps us a better understanding of global climate.

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Speaker 1: On a more specific note, UM scientists think it will

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Speaker 1: be able to look, uh, look at changes in in gravity,

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Speaker 1: changes in density too, to determined shifts and water mass

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Speaker 1: caused by droughts or floods. And it will also also

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Speaker 1: allow us to better understand plate tectonics, UH, seismic activity.

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Speaker 1: You know, what's what's happening underneath underneath the soil um

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Speaker 1: in the crust to you know, the leads to two

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Speaker 1: two earthquakes and uh another phenomena and uh and just

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Speaker 1: the geological geophysical processes that underlie the the Earth. Sorry,

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Speaker 1: but it's pretty it's pretty I'm getting a little long

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Speaker 1: winded here, but it's pretty pretty, pretty awesome, and that's

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Speaker 1: why we're looking into it. So I hope you've inspired

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Speaker 1: some reverence for gravity and you besides the kind of

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Speaker 1: gravity that trips you up and makes you fall flat

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Speaker 1: on your face and gravity is pretty cool. Um. So

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Speaker 1: now we would like to take a moment to imagine

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Speaker 1: a world without gravity. Oh, we were going to talk

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Speaker 1: about it or just imagine it, because I was just

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Speaker 1: going to picture it. Yeah. One thing that's really gonna

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Speaker 1: suck is that all the atmosphere is going to drift

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Speaker 1: off into space and we're not gonna be able to breathe. Yeah. Also,

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Speaker 1: I don't think I don't think our hair is gonna

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Speaker 1: look right. I mean, how do you style your hair

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Speaker 1: for that? That's true? I mean what kind of products

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Speaker 1: could could combat that effect? Um? I think that it

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Speaker 1: would suck if the the oceans boiled away and just

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Speaker 1: kind of float it off into the void um. On

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Speaker 1: a more mundane level, I think eating would kind of

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Speaker 1: pose a number of challenges. Only the astronauts. They'd be

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Speaker 1: sitting there, happy as you please, eating their dinner out

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Speaker 1: of their bags. Everybody else would just be in full

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Speaker 1: freak out mode. Yeah, like trying to run after their

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Speaker 1: hamburger which had floated off into bun Yeah, and the

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Speaker 1: chop bits of onion and I'm sorry, catch ups. Just

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Speaker 1: a globular thing floating out there. Yeah, yeah, that would

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Speaker 1: be bad. So that would be a world without gravity,

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Speaker 1: and we hope that we may never encounter it. So

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Speaker 1: if you want to tell us why you think gravity

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Speaker 1: is cool or maybe not so cool, send us an

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Speaker 1: email at science stuff at how stuff works dot com,

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Speaker 1: or go read about gravity where we're at site. Yeah,

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Speaker 1: and when you got to check out the blogs where

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Speaker 1: we handle any number of scientific specs, including zombies from

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Speaker 1: time to time. Thanks for listening, guys. For more on

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Speaker 1: this and thousands of other topics, is that how stuff

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Speaker 1: works dot com. Want more how stuff works, check out

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Speaker 1: our blogs on the house stuff works dot com home

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Speaker 1: page