Artificial Gravity: Cosmic Wheels and Hurtling Towers

be like to to float free, uh, inside of a capsule? Yeah? And people obviously imagine the very simple stuff, right, you know, floating from one end of the room to the other, not being able to walk normally, maybe fear that you would experience some motion sickness. You know, many, many people who go to space I think at least half I think is the number, experience some kind of space adaptation problems space sickness once they arrive. That might go way

after some time. Yeah, Or you tend to focus on the amazing and the horrible ideas, like you know, for instance, how fun it would be to drink orange juice and space by chasing the globs around the capsule, or the more you know, they're definitely horrible or or almost horrible scenarios such as, of course, uh you know, the bone mass density loss, as well as the problem of trying to poop in a toilet. Right, I thought you were

going to immediately go to using the bathroom. I was immediately going to go to the bathroom, And then I thought I should I should reference like the really pivotal problem here as opposed to just the one that is difficult. No, I mean, going to the bathroom isn't necessarily a big problem. You know, you it might not sound all that appealing to essentially poop into a vacuum cleaner but or bag. You know a lot of people maybe that's something they've

always wanted to try out. It's not necessarily a horrible idea, but it will definitely be horrible. I don't know if you make a mistake in this process. Right, That's where the horror stories kick in, is when the the the super expensive space toilet malfunctions. The same thing, of course is true, well not exactly the same thing. A similar thing is true of you mentioned chasing orange juice globules with your mouth to hunt them down, but eating in space, I mean, we depend on gravity so much for a

lot of our eating activity. Keeping food in a container. I mean, you just can't compose dishes in space. You've gotta again kind of like you poop into a bag. You've got to eat out of a bag um, or have something that's relatively solid and doesn't have crumbs that are going to get everywhere. I mean, can you think about trying to salt your food in space? You sort of need to like salt into a bag and shake it up or something. Yeah, or just have like a hot sauce packet that you you add into your own

mouth afterwards. I feel like I could get buying a number of like bagged curries and whatnot. Yeah. Now, of course, another thing astronaut's report about zero gravity environments is that your sense of taste is all jam up, Like you

can't taste things the way you normally would. And part of this probably has to do with the fluid redistribution in your body that leads your head and upper body to swell because you don't have the normal gravity pulling all the fluids in your body towards your feet, which your body is naturally trying to overcompensate for another gravity tidbit that that I always find fascinating is that I believe Mary Roach pointed this out in their book Packing

from Mars. If you're in a microgravity zero gravity environment, your bladder doesn't fill up from the bottom up. It feels like in the center, right, It fills like all around towards the very center. So you don't realize that you need a urinate, uh, typically until you're absolutely about to burst, because because we have evolved to sense the to detect that the need for our own urination on a gravity invite, in a gravity environment, on a on

a world with gravity, we are creatures of gravity. It reminds me of a piece of terminology I haven't really thought of since elementary school, but back and there would be a thing that would be like a p quote emergency. Remember the emergency. Yeah, well, I mean I guess if you have kids, there's such a thing as an emergency. Yeah.

I have a five year old son, and so he has these where it's like suddenly it's super dire, like you have he has to run outside of the front doors closer to him, uh, you know, grabbing himself the whole time and going I gotta go pee and the immediately paying Um, this is the kind of thing adults tend not to experience unless perhaps you go into space. Right, So those are the the less dire things now you

already alluded to. Of course, the deterioration of body tissues, loss of bone density, loss of muscle mass, and and and all the different negative consequences that happened to the body under zero gravity or microgravity conditions. These things can really stack up. And it's not a trivial effect. Astronauts

have to exercise constantly when they're in microgravity environments. They've got a spend hours a day working out in these weird machines just to try to offset some of the damage that's being done to their bodies by the lack of gravity in their environment. And it's still not enough, all right, I mean, they still come back to back to Earth messed up, and they need time to really reacclimate. Hopefully they will eventually come back to something like full health.

But but it's not good for you. Yeah, And and of course one of the problems is that uh, astronauts want to go back to space, so they're not necessarily going to be as forthcoming about the about how they're exactly feeling. Yeah, I guess that is a thing to worry about. You'd hope that they'd be accurately reporting how bad it is, but maybe they just they want to

get back up there. Yeah, I mean that, that's that's what what I've I've heard is that generally speaking, and you don't go to space then and you're like, oh, that's enough of that. I'm good an astronaut. A person's worth their whole life to do this for not even just to do this, but for the chance of doing this. Of course they're gonna want to go back. So my question is, why don't the people who run the I S S. I don't know whoever they are, NASA, I

guess maybe not NASA space agencies around the world. Why don't the people who run our space stations just take advantage of the Holtzman effect and put some gravity plating in there so that you can walk around like a normal Earth humans. A. Yeah, so yeah, you're so you're drawing in both Star Trek and Dune here, but they're they're both prime examples because they're straight into the blender.

Because this is uh, this is one of the key aspects of our science fiction when it comes to gravity or lack of gravity and space, they're basically three models. Either you're gonna you're gonna try and go hard science and have some sort of an artificial gravity scenario like some of the realistic scenarios we're going to discuss in this podcast. You're gonna just go you know, micro gravity zero G and have people floating around, which of course

can be difficult from a special effects standpoint. Or you're gonna go space wizards. Yeah, you're just gonna go magic artificial gravity and just say hey, we let's star trek.

We have gravity plates in the floor. Of course there's gravity. Uh, it's the and in in in Dune you have the the Holtzman effect generated by the Holtzmann field generator, and Herbert never explain exactly what it was or how it worked, but it allowed for the generation of anti gravity faster than light travel, personal shields, artificial gravity on ships, you know, all the things you need to sort of go ahead and establish your interstellar uh empire, and then tell the

stories you want to tell. You know, I'm okay with that because in lots of science fiction stories, essentially they're trying to tell a character drama or it's a fantasy story set in space. I don't need all science fiction to be hard science fiction, but I really do appreciate hard science fiction that tries to take the physics that we know seriously. This does not. But that's okay, you know,

that's doing its own thing. Yeah. I mean, Herbert had areas that he was definitely going to focus in on, such as ecological issues, philosophical, religious, cultural issues, and of course this the drama that is especially seen in the first book. So I kind of some slack. I'm fine with some magic anti gravity. Now, in terms of sci fi properties that do take it really seriously. What are What are a few films that come to mind? Well, of course you you immediately think of two thousands, one

of Space Odyssey. Now that's got multiple spacecraft. There's a space station and there's a spacecraft that both use something we're going to talk about later in the episode rotational UH structures for centripetal force driven or centrifical, centrifugal or centripetal force driven artificial gravity scenarios. Also, there is a good artificial gravity ship in the Martian UH, and I remember I think there's one in a space station and Interstellar isn't there. Yes, I do believe I remember the

spinning situation. And I also want to point out James S. A. Corey's Expanse series, both the books and the sci fi TV show, which which does I think a really good job of going after from near future interplanetary culture and technology. And it's also the only sci fi property that I can think of that that actually explores one of the anti gravity schemes we're gonna we're gonna be discussing today

linear acceleration. Well, linear acceleration. I can see why that's limited because it has sort of limited applicability if you're going to try to be real about like it only works in certain types of ships doing certain types of things to a certain extent. We can we can chat about this, this this later. Okay, we'll correct me. Well,

I don't know, but it's not really correction. But I think one of the problems is that linear acceleration model calls for a spaceship that is not a seagoing vessel transported into space, because, as I said before the program, I think a lot of our science fiction and our sci fi ships are essentially seagoing vessels and tales of seagoing vessels and sea and Captain's uh taken from Earth and transposed into space. I mean that was basically Gene

Roddenberry's a whole deal with Star Trek. That was m was the Master and Commander books that he wasn't No, it was a different one. Um. I can't remember that the series offhand. But anyway, he was inspired by by literary tales of of of adventurous humans at sea. Uh No, well, maybe I don't know. Well, I guess the Wrath of con is yeah, from Hell's Haired I staff at the right.

But it's it's more difficult with linear acceleration because you have to you have to take that concept of an Earth vessel and you really have to literally turn it on its side. You have to think instead of a ship going from port to port and stopping, you have to think about long, continuous journeys. But we'll get into all that in a bit. Okay, Well, I guess we should first just take a real quick look at what is the problem with artificial gravity, with generating gravity and space.

Why can't you just do it? Well, I mean, so gravity is something that is a field generated by generally we think of it as mass. It's generated by the stuff in the universe, energy and mass, you know, much more by matter that has mass. So we all know that objects that have mass have a mutual attractive force. They tend to attract one another. And you know, we've

known this for a long time. It was the laws of gravitation were to a certain extent well explained by Newton in the seventeenth century, and he basically described the laws of gravitation in a way that that makes sense for most of the stuff we're going to be looking at,

for planets, for spaceships, for things like that. Now. Of course, later Albert Einstein revolutionized our understanding of what gravity is by telling us that gravity is the curvature of space time, and that sort of matter tells spacetime how to curve, and that the curvature of spacetime tells matter how to move. So let's start with masks, and I think that's the that's that's the essential part. That's that's a pretty easy to understand here. So everything with mass, from a dust

mote to a star, exerts a gravitational pull. The strength of the poll, however, increases with mass. And proximity to the object. So a smaller object can only attract another small object of it's nearby, but a large object can pull in objects from across the vast distance. And this is kind of this is key to the structure much of the structure of our of our universe. I mean, this is how accretion occurs, with little specks of space

dust and gas forming together and snowballing into larger cosmic bodies. Yeah, I mean, this is how our solar system was created. Was the coalescing of objects by the force of gravity. Things are attracted to each other, eventually becoming stars, planets, all that. Yeah. And then Albert Einstein's general theory of relativity comes along and propose that the gravity is a curve in the fourth dimension of space time. And there's

proof to back him up. Given sufficient mass, an object can cause an otherwise straight beam of light to curve. Astronomers called this effect gravitational lensing. Yeah, this was shown experimentally.

It was one of the fir speak experimental proofs of Einstein's theory of relativity is that you could see light from stars passing behind the Sun bending as it came right around the Sun. So you know, if you could have a solar eclipse and shield out the light from the Sun, you could see stars in the background being warped by the Sun's gravity as the beams of light passed close to our Sun. Yeah, and similarly, the less

gravity there is, the slower time passes. And this is a phenomenon is gravitational time dilation, and this is this is the less key to what we're talking about. But it just drives home like the place of gravity, uh in our universe. Yeah, it sounds this is one of those things that sounds like fantasy, but it's absolutely true. And you saw that We mentioned the movie Interstellar earlier.

There's actually, Uh, there are a couple of great scenes and the demonstrate this where they go down to a planet with an incredibly high gravitational pull and uh, while they're down there on the planet, much less time passes for the people on the planet than passes for people in orbit farther away. Yeah. As a physicist Paul Davies points out, time runs a little bit faster in space than it does down on Earth. It runs a little faster on the roof than it does in the basement,

and that's a measurable effect. Then's the basics on gravity. But then there's also this additional area of quantum gravitation and the idea that that there is a there's a hypothetical particle, the graviton, which in theory could cause optics to be attracted to one another. Yeah, and this would be the mediating particle of the force of gravity, in the same way you've got like the electromagnetic force, the mediating particle there is the photon. Hypothetically you'd have some

mediating particle delivering the force of gravity. But we've never seen gravitons in the universe. Right. This is the this whole hypothesis comes together because quantum theory, to refresh, addresses how the universe works at the smallest subotonic levels, and the resulting model here does not explain gravity. So gravitons and the theory of quantum gravity isn't a attempt to reconcile general relativity with quantum theory. It's a basically an attempt to patch up a hole in the standard model

of particle physics, which cannot explain gravity. Now, the last time I read seriously about gravitons was a few years ago. I wonder if any recent experiments in our particle colliders have have shed any light on that. I mean, our physicists now thinking gravitons are more likely or less likely. So well, we certainly don't have any definitive proof on

the matter yet. But I guess for the purposes of our discussion here, since we don't have proof of gravitons, we can't really come up with a scheme to employ them or manipulate them in some way that would give us artificial gravity. Yeah, so, I guess are the point of our bringing up gravitons is that you can't just wave a magic wand and say, ah ha, gravitons will be the thing we use to create artificial gravity in space.

I mean, we don't know if they exist. If they do exist, I'm not sure anybody has a coherent idea of how they could be harnessed to provide artificial gravity in space. It just seems like I don't know what is So if they're generated by mass, would you not need mass to generate them? Yeah, I could. I looked around in my research and I couldn't find any, like,

any real theories about how gravitons. If the exists might be utilized in this fashion, and I'm not I'm not aware of any science fiction that explores the possibility, but I would love to know about it. I think when it does, it's more just the kind of it's the hand waving magic. Right. So we come back to mass, then yeah, you could I guess, have a spaceship that's as massive as the Earth, and then that would have that would give you the gravitational pool you'd need. That's

not exactly a terrible idea, and it's not unexplored. I mean there have been these ideas, for example, in you know, stellar engineering projects that say, hey, so let's say we want to travel to another solar system, wouldn't it be easier instead of trying to build an arc ship to take us there, to see if we can build a structure around the Sun that will reflect some of its radiation in and allow us to steer the movement of the entire Solar system. Oh yeah, yeah, I just move

the Solar system. Yeah, so like the Solar system becomes our spaceship. You can build these things called a hypothetical structure called a scatterw thruster. Essentially, it would just drive the Sun Yeah. That actually features into No Surprise and Eda in Banks book, but I'm not going to say which one because it's kind of it's kind of a spoiler, Okay,

but it's one of them. Leave it, leave it there. Yeah, So that is one idea though, if you wanted to travel through space on an object that has Earth gravity, you could just take Earth with you. Of course, it wouldn't really make sense to say, well, I want to build a spaceship that generates Earth gravity through natural mass generating effects, because then you would just be building a

spaceship the massive Earth. Right. And if you can do that, then I mean you're already You're already a pretty powerful civilization. I'm not sure where you would rank on the Kardashian scale, but you'd be you'd be potent. Definitely a cardas chief one, maybe a cardas chief two. Alright, So we've talked about these scenarios involving natural gravity and and the idea of manipulating natural gravitational forces. Luckily we're not, we're not forced

to contend only with those. We can also deal with artificial gravity, not in a magic sense, but in a but in a real sense. Yeah, and in this way, there are ways to generate artificial gravity that are not hypothetical or speculative at all. I mean, this is totally easy, standard settled physics, because one of the insights of modern physics is that gravity is in fact indistinguishable from acceleration.

When you're being pulled toward a planet's center and the planet has a mass such that it generates a surface gravity of nine point eight meters per second per second, which is what Earth's surface gravity is, right, or whether you're accelerating through space at an acceleration rate of nine point eight meters per second per second, the effect you experience is exactly the same. You can't tell the difference between these two situations. And so knowing this, we couldn't

turn the idea of acceleration to our advantage. And that's where our first model comes into play. But first we're gonna take a quick break. All right, we're back. So the first model of artificial gravity we're going to discuss here is the one that I alluded to earlier and discussing the expanse, and one that I think, by and large, I cannot think of another single science fiction property that

employs this as their artificial gravity. On a spaceship. But yeah, linear acceleration, I can't really think of many that do. But so, what's the basic idea here, Robert? All Right, So, if you've ever written on a roller coaster and felt yourself plastered to the back of the seat, then you've experienced some of the power here. If you were in a fighter jet and you were, you know, traveling at a sufficient speed to pull you multiple g's, you're you're

also experiencing this as you're pushed back into the chair. Right, So, if you can imagine being in that fighter jet and you're being pulled back into your chair, except instead of going back into your chair, you put your feet on the chair, put your head in the direction that the fighter jet is going, and the acceleration rate of that fighter jet is nine point eight meters per second per second, it would suddenly feel a lot like it feels to stand on the ground. Right. Imagine a skyscraper as a

rocket ship. Imagine it blasting through space at such a speed that the G force uh equaled the pull of Earth's gravity on the internal environment. I'm actually gonna read a couple of quick quotes from James S. A. Corey's UH first Expanse novel, because I believe that these really capture what we're talking about. So he's describing the Donager space ship here quote. Like all long flight spacecraft, it was built in the office tower configuration. Each deck one

floor of the building. Ladders are elevators running down the axis. Constant thrust took the place of gravity. Now, there's also a Mormon generation ship in the book that uses both linear thrust and a rotating wheel, which we'll get into, and this is the description for it. Each compartment within the massive rings was built on a swivel system that allowed the chambers to reorient to thrust gravity when the ring stopped spinning and the station flew to its next

work location. Okay, so by describing these ships with floors like an office building, what you what you should really picture is like you've got a skyscraper and it's flying through space with the top of the skyscraper as the front the nose of the ship, and all of the floors are where your feet would be towards the back of the ship and your head would be facing the front of the ship. It's taking the holes like starship

enterprise situation and turning it sideways. If you imagine the starship Enterprise flying in such a way that the top of the ship is the front of the ship. I realized this gets complicated when you're talking about outer space. But you're you're taking and in this part of the problem.

Like we we understand the movement of things in our situational uh positioning in a gravity rich world, and when we try and take it out of that, it's it's kind of hard to picture some of these, uh, these situations, right. But yeah, so if this is taking place in space, you would be able to generate a force towards the

floor that simulates Earth gravity. Now, this would this would have some complications I'm imagining because in order to perfectly simulate Earth gravity, maybe you don't care how perfect it is, but if the goal was to perfectly simulate Earth gravity, you would need to be constantly accelerating at nine point eight meters per second per second, that's a lot of

constant acceleration. You're always going that much faster. Yeah, yeah, I mean, we we see the required propulsion at work when a chemical rocket creates enough thrust to counter this gravitational pull and achieve escape pul loss. But they're only achieving it from a matter of seconds or minutes. For our spaceship here are theoretical spaceship, our office building on

its side, you'd need something more constant. So just to refresh on the gs here, standing on the Earth, you'd experience one G in free fall, saying an elevator or the vomit comet, you'd experience zero G. At two G

feel twice as heavy. So you'd need a spaceship capable of propelling you fast enough, like you said, to exert a constant one G. So one of uh, the sources we turned to for this was a wonderful two thousand seven book Artificial Gravity, edited by Giles Clement and Angelie Buckley, And there's an article in there by Buckley, Clement, and William Pulaski of NASA's Johnson Space Center, and uh they point out that a spaceship could, in theory accelerate for

the first half of a Mars journey, then decelerate on the second half, and in doing so maintain one G and reach Mars in two to five tays depending on the distance I mean that would be. You'd have to have incredible power, yes, incredible thrust like a powerful fuel to accelerate that much. Also, I'm how did so that

they explain how you do the flip over. You'd have to be accelerating one g the like half the way there, and then you have to be decelerating at one g the other half of the way there, which means I guess you'd have to flip the spaceship around so that

the floors stays the floor. Yeah, or you'd have to have some sort of like an internal habitat that's like a capsule on it rotates that or yeah, I guess you could have a spaceship where the floors and ceilings are both can both work as floors, right, And of course the distance here involved not to go into the Mars opposition details here too much, but the maximum distance between these two planets is two and fifty million miles with the sun between the two. So I guess that's

not doable in two to five days. The I would assume you would not try and make the journey there unless I mean, but but if you're achieving speeds like that, then you know, maybe you'd go you'd go for it, but that the average distance is more like one forty million miles and the closest possible distance is a tantalizing thirty three point nine million miles. But anyway, that's this

is the basic Yeah. But yeah, you would need to have uh, some pretty awesome power at your disposal, so awesome that I believe in the Expanse books like they basically can't be the authors who publishes as as James S. A. Corey, Uh, they had to sort of create their own fictionalized propulsion breakthrough to make that possible. Here's where you need the magic in this version. Yeah, instead of having magic gravity plating,

you have magic propulsion. And I guess this is the case with a lot of sci fi Like you, there's a certain place you you want human civilization and or alien civilizations to be at, you know, to be able to discuss them and look at the ramifications. But yeah, we don't have all the steps worked out about how

we'd get there. There's there are certain breakthroughs that we need to take place, and you could explore them and try and come up with some sort of uh, you know, complex of physics space theory, or you could just you know, put a post it note there and and maybe write magic on it. Yeah, even in a lot of so

called hard sci fi or mostly hard sci fi. You know, you've got like a list of steps in how something is achieved, and most of the steps are something that's scientifically rigorous, but one of the steps in the middle is like, here's a magical element. I mean, it's kind of like with a lot of speculative properties that I enjoy. Sometimes they'll be something completely ridiculous, uh, something completely magical, But then you discuss all the real world ways it

might play out. Like one example that comes to mind is a World War z you know, the Zombie book. Not so much of the movie, but the book looked at it's some possible ideas for how this would play out, like culturally and politically, uh, without really getting bogged down in the fact that zombies are are kind of a dumb idea and can't actually exist. But it's like, roll with me. Zombies are real, Let's discuss how this might work.

I want to defend zombies just a little bit. There are different types of zombie scenarios, and some some are much more plausible than others. Reanimated corpses, no, but you know, rage zombies, some kind of weird virus, okay, maybe, okay, all right, yeah, I mean we have raybies. I mean, we don't have rabies, but there is ray you never know, alright, So you're probably wondering. Okay, we've established how this would work, we've talked a little about the sci fi, but what

kind of work has actually gone into testing it. Well, they've been at least a couple of experiments. The European Space Agency e s A experimented with this in nineteen eighty five on the Space Lab D one. Now I couldn't find an image of it, but I'm assuming it's it's the same sled or one similar uh that was used in the nine eight one experiment where they were,

you know, messing with the nineteen eight one. It's basically this, this chair on a if you okay, imagine a short train track that you could fit in a room and then you have a chair on it. I'm glad, I'm glad you've provided this picture. But this is crazy. It

is It looks crazy. There's so there's a imagine a little train on a little train car, and there's a chair on it, and a chair swivels and you have somebody strapped into the chair with a bunch of you know, electronic dud dads connected to them, and then they would, uh, they would essentially like fly back and forth on this little train track with the with the seat swiveling along the way. It's a very Terry Gilliam contraption, isn't it. Yes,

it it does. It looks very Terry Gilliam. Now, they tried this out and it peaked speeds, it only provided point to G and according to a Clementon company, the threshold for the perception of linear acceleration in humans is on the order of point zero zero seven G, and the threshold for humans in space seems to be more like between somewhere between point twenty two and point five G. Yeah.

I've got some notes about that later on, about what exactly would be tolerable as artificial gravity, But I don't know, maybe maybe maybe you're getting to it right now. So you the the idea here is that you wouldn't necessarily have to have one full G in order to counteract some of the worst effects of microgravity. Yeah, it kind of comes down to what are you looking to do? Are you looking to to to counteract the effects of microgravity to a certain extent to like just get you

there a little bit, or have like a perfect Earth simulation. Right, do you want to, um, you know, awaken a comma patient a board your spaceship and trick them into thinking that there's still on Earth, right, Like that's a tricker scenario. I mean maybe you could do it by telling them that they're they're they're nauseous or something. I don't know, Um, they have they have some sort of illness, but you've

got an inner ear problem. Gravity is normal. Yeah, as a Clinton company point out in the article, quote, perhaps it is not necessary to perceive artificial gravity at the cognitive level for it to be effective as a countermeasure. However, for purposes of defining the comfort zone of astronauts and artificial gravity environments, whether it's a rotating spacecraft or an onboard centrifuge, it would be extremely useful to determine the

threshold value of perceived artificial gravity. Unfortunately, there are no plans to put a human centrifuge on board the I s S, at least in the near term. So when it comes to g's um, you know, Mars is point three seven six gs, Neptune is one point fourteen G Saturn is one point of seven ges. Guess they're not gonna be standing on the surfaces of Neptune or but we have stood on the surface of the Moon, which

is point one six gs. And Clement and Company point out that when astronauts visited the Moon, they had trouble figuring out which weight was up and down. They didn't they didn't perceive a four point five degree floor tilt in their landing unit during Apollo eleven. Can you imagine that, Like you're you're on a slope, but the gravity is so weak you can't you don't get that you're on

a slope, like you can't feel it. And then when they're bouncing around out there on the lunar surface, Uh, there were a lot of dumbles, and a number of these stemmed up from the inability to evaluate ter rain slope. Yeah. Again, like you can't tell the difference between uphill and downhill. It's hard to imagine. Yeah, and yet, I mean the moon gravity is perfectly enough to keep you tethered to

the surface of the Moon. You're not gonna fly away or anything, right, Yeah, You're not gonna leap up and achieve you know, escape velocity. Now there is another study and this is actually a proposed study currently and this is the NASA funded turbo lift the turbolator. Yeah, and this, Uh. The idea here is to combat the effects of microgravity by accelerating an astronaut literally had one G for what a round of one second, and then it's rotated uh

degrees to prepare for one G deceleration. It's kind of like being shaken up in a cocktail shaker, uh, and only your legs always point in the direction of the shake it. It would, theoretically, according to the the proposers here, uh, feel like bouncing on a trampoline. So this would be a suggestion, not for a habitable environment or from a for a spaceship, but maybe for essentially some kind of

exercise machine. Is that what we're thinking? Yeah, that that's what That's what I'm getting from this is that said quote. The intermittent loading is intended to reduce or eliminate the physiological deconditioning in a comprehensive multisystem manner. It would be it would be a situation where like, hey, Joe, I know you've got stuff to do on the spaceship, but

it's time for your your one G treatment. You need to climb in the capsool here and we're gonna shoot you back and forth for however long your treatment last. The flipping bullet. Yeah, Now, this does indicate that there are these two very different schools of thought about what to do when generating artificial gravity. I guess we sort of alluded to this a minute ago, but you still should keep in mind this question of what is the goal.

Is the goal just to have an environment you can go into often enough to offset some of the negative health effects of being in space. Is it just sort of like tiny jim for your body to stay healthy, or are you actually trying to create an environment where some of the effects of Earth gravity are simulated for normal living purposes, so you can salt your food, so you can go to the bathroom without pooping into a

vacuum cleaner. Now I do have to say that, um, I can't help but think that this the jumper scenario, this turbo lift scenario, I could see it working if you had somebody in a hibernation state or some sort of suspended animation, like maybe you load their their corpsicle into one of these and shoot them back and forth. To to keep their to avoid any debilitating effects involved with their space travel. But of course for that to work, you have to have some sort of hibernation um, a

technique worked out, and that's a whole. That's a whole another podcast topic. Now. In terms of complications with this linear model here of artificial gravity, you of course you have to be in motion, you right, to be able to produce that effect. Uh, you have to always be on your way somewhere or taking a roundabout way to continue the effect. But I'm not sure if that's such

a detriment because, after all, space is big. The distance between planets, but certainly between stars is vast, and there's plenty of room to to run around out there. Well yeah, I mean if you actually want to travel to say, another star system, and not just say to Mars, but if you want to go to Alpha Centauri or wherever. I mean, as much acceleration as possible is good. Uh, it's still I guess I have the question about what the propulsion idea is, Like, how do you constantly generate

that much acceleration exactly? Yeah, I guess with some models you have these ideas of like you know, kind of like beamed propulsion back from Earth where you line you know, you like you line up this payload delivery of energy. Um, that's right. That's what we have in Blindside, the novel that you just finished reading and I'm currently reading. Yeah. I mean the whole thing about this is this seems

like a method that would work and would be very interesting. Um, but I guess it's just waiting on some kind of abundance of energy and propulsion technology and the than the means to use it or the opportunity to use it. All right, Well, that's linear acceleration for you. That's one model. We're gonna take another break, and when we come back, we're going to dive into the much more popular artificial gravity scheme, the one that you see in the movies.

And then of course is the spinning habitats, the Taurus, the standard towards the double Taurus. All these different models were of course talking about, uh, the manipulation of centripetal force. All right, we're back. So, Robert, you've seen two thousand one of Space Odyssey. Oh yeah, one of my favorites. And so if you've seen that movie, you've seen at least a couple of different versions of the design for

artificial gravity that exploits centripetal force or centrifugal force. I'll talk about the difference between them in a minute now. One example in the movie is this giant space station called space Station five V for five, and it's shaped like a wagon wheel. And the other is this round module. It's a spherical module within this spaceship that how controls in the movie, the spaceship the Discovery one, which is the one that's on the way to I think it's

Jupiter in the movie and Saturn in the book. Is that right, I believe. So, yeah, this is the one that's like really round in the front and long in the back, right, And so in this crew module in the Discovery one in the movie, you see a gravity like effect pulling passengers to the floor along the equator of this compartment. So we can see the effect in this one scene where Frank Pool, the astronaut, is jogging in full circles around the inside wall of the sphere.

So he's jogging laps, but he's not jogging horizontal laps. He's jogging full circular orbital laps. Yeah, say it's one of it's it's one of you, not like the greatest sequence in a science fiction film. It's just so beautiful

and and and and and thought provoking. So there are multiple ways that you could set something like this up, and I'll explore a few of those models in a minute, But the basic idea is that you create a spinning structure within your spacecraft, and the outside edge of the spinning environment becomes a floor that pushes up against your feet the same way the ground pushes up against your feet as you are attracted steadily towards the center of the earth. So, in other words, it simulates the effect

of gravity. Now, like linear acceleration that we just talked about, rotation based gravity also relies on the pseudo forced sensation generated by inertia to simulate gravity. It's your body's inertia feeling like the gravitational force that pulls you towards the center of the Earth. Now, in the case of the spinning model, this is known as trifical force or the centrifugal pseudo force. Now, there are two terms that are

easy to get confused here, centripetal force and centrifugal force. Uh. Centripetal forces is the real force in physics, and this

is really there two sides of the same coin. So centripetal force is something that you will notice if you've ever done the old experiment, you know, the thing you do when you're a kid, is you get a bucket of water and you spin it around in a vertical circle so that the top of the circle your buckets upside down, but the water stays in the bucket doesn't fall out like it would if you just held the bucket upside down, and you you realize intuitively something's going

on there about the force of your swinging motion with your arm. For some reason, it being at the top of a circular motion keeps the water in the bucket in a way that just turning the bucket upside down in the same place wouldn't. And so what that is is the centripetal force of the bucket pushing down on the water to hold it in, while the inertia of the water flying in this circular motion wants it to fly off in a tangential pattern, uh, and a tangent

going straight out from the path it's flying along. So you can think about it's sort of like anytime something is is flying around in a circular motion. Say a space station is orbiting the Earth, what it really wants to do is keep traveling in a straight line forever. Right, So if you've got the I s s it's orbiting the Earth, what what it wants to do if there were suddenly no Earth is just travel straight ahead, So

it just keep going off into space. But what the Earth does is it exerts a certain amount of force, pulling that the space station down towards its center of gravity and curving its path. And the same thing happens when you've got an object swinging in a circular path, but contained by some kind of physical structure or force,

like your arm and the bucket holding the water in place. Now, so, so the centripetal force is the inward force that pulls everything toward the center of motion in a circular pattern. The centrifugal force sometimes referred to as a pseudo force because it's really just inertia in a moving reference frame. That's the apparent force that acts on an object moving in a circular path to push it outward from the

center around which it rotates. And this would be taking the place of the gravity that actually pulls your feet towards the ground on Earth. Now you can also feel the intuitive physics of this on your body, just in

your imagination. If you've ever done the carnival ride Robert, where you get on the what is it the cyclotron, the circulator gravitron, it's the thing where they put you in a cage and your back is against the wall, and it's this big disc where everybody's back is against the inside wall of the disk, and then it starts spinning you around very fast, and suddenly you're just pinned

to the back while you can't lift your arms up. Uh. And it's it's all this force that's that wants to throw you off into space, but in fact there's a wall they're stopping you, so instead of being thrown off into space, you're just pinned to the wall. Yeah, that's a carnival death machine that I've probably only written once, but but I have written the similar device, and that

is of course the like the pirate swinging ship. You know, Okay, it has a similar similar effect as the bucket scenario if the pirates swinging ship or to go all the way around, not the ones I ride, but so interesting. Uh well, it's also yeah, this the centripetal centrifical force. It's the same thing also that allows you in a

roller coaster to go around a loop. Roller coasters that have loops because the force that's keeping you, you know, you want your body wants to continue on a straight line as it gets to the top of the loop and just be flung off up into the sky. But instead you've got that roller coaster they're holding you, so instead you're pressed down into your seat, which is actually straight up from the ground. Um. And so the same

thing you can imagine could happen in space. If you've got a space environment and you're on a thing that's spinning, you know that you will experience some kind of force pinning you to the outside wall of that spinning structure in the same way as as the bucket of water and the loop de loop on the roller coaster. So then the question is how do you generate the right

amount of force there. Obviously, you don't want your the inside of your space station to be like the Gravitron ride where you can't even lift your arm and you're just pinned to the floor. Uh, you want to simulate something within the realm of one G or one of these fractions of one g that seemed like they might be a tolerable living environment or at least help offset

some of the effects of micro gravity. And so you calculate how much force you generate towards the floor of a spinning structure by multiplying the radius of the structure by the speed of the rotation squared. So your two main variables are going to be how fast is the thing spinning around and how big is it? And since you're multiplying these together, the bigger the structure is and the faster it rotates, the more force there is towards

the floor. And unlike the problem I just mentioned about being pinned to the floor, actually mostly the problem that we're going to experience is how to generate enough force, not how not to generate too much. Alright, so we have the basic principle here. We've already mentioned some of the sci fi scenarios. But what are some specific proposals. Well, you've got some basic shapes that you could think about, and then I'll talk about how those shapes have been

proposed in the history. Now, one thing you could obviously look at is something like the two thousand one space station, which is like a wheel. So you'd have a donut, and inside the donut it's hollow, and people are walking around on the outer wall of the inside of the hollow donut. This would be the torus shape or the wheel shape. And we tend to gravitate towards this because everyone loves the wheel, like the wheel is such a

such an excellent human symbol. There, of course we want to see it in space, uh, magnifying our glory as a species. Yeah, well, there's that. There's there's the flying saucer. You know, we love to see a wheel that way.

There's the passage in Ezekiel about seeing wheels, wheels and wheels. Now, there's also sort of the cylinder model right where you you'd have the same effect where you'd be moving on the outs or the inner wall or sorry, now here you'd have a similar effect where you'd be walking along on the inside of the outer wall of a spinning cylinder, and that would be a lot like the effects caused

by the wheel. Another thing that's kind of interesting is the idea of something like a bolus or a or a tethered counterweight, where instead just imagine putting yourself in a box and then tying that box via a rope to an equally weighted counterweight out in space, and then you just the two of you rotating against one another. This would also generate a force toward the outer floor of the box. The you know, the wall facing away from the rope would become the floor. Okay, it's less elegant.

And the other thing about it is that it is called a bolus, which brings to mind various things, uh, flying out of either orifice. Right, so you're saying, like, if you had to perform the Heimlich maneuver on a fellow, ask or not, they might cough up a bolus of food they've been choking on. Or you're reading, well, you're in the bullus. Yeah, And then of course I've also read, uh, I think I've read in like space manuals about uh using the toilet in space, they refer to the fecal bolus.

So the less you have to think about the fecal bolus or the traditional you know, bolus of food that you're your your your tongue helps form before you swallow. Yeah, you don't want to think about that when you're spinning around in a capsule in space. No, you don't, Robert, No, you don't at all. Okay, So let's look at some specific examples of proposals for for spinning artificial gravity stations

in spacecraft throughout the years. And here I'm gonna cite a lot from a specific chapter from that same book you mentioned earlier about artificial gravity. This would be the chapter on the history of artificial gravity, and that's again in that book by uh by Clement, Bookley, and Pulaski. So one of the earliest known designs for a space station with artificial gravity created by rotation comes from the Russian physicist Konstantin L. Tilkowsky, who lived from eighteen fifty

seven and nineteen thirty five. And Tilkowsky was an interesting dude. He was one of the pioneers of rocketry theory, but he also was one of those futurists, right. He was one of these people who became obsessed with the idea of colonizing space. He wanted humans to colonize space. He wanted earth domination of the galactic neighborhood. And one interesting story I found is that he at one point built a big centrifuge to who test out the effects of

acceleration or artificial gravity on the human body. But he didn't use human test subjects. He tested it on chickens and made the gravity chickens rest in peace anyway. In his manuscript the title, which translates to free space in eighteen eighty three, Tiolkowski sketched a hypothetical spacecraft and designed how you could spin a spaceship to give it artificial gravity on the outward facing walls. Another pioneer who would be Sergey kral V, one of the great minds behind

the Soviet space program. He was a really ambitious guy, and in nineteen fifty nine he was designing a trip to Mars in nineteen fifty nine via a spacecraft called the Heavy Interplanetary Manned Vehicle. And no, this was nineteen fifty nine. This was before Urikagarin's first space flight in nineteen sixty one. No human had been to space at this point. And this guy's like, all right, we gotta

get this Mars trip on the road. Um, And anyway, this the spaceship that he was designing, the h I m V. It would have a mass of seventy five tons, a length of twelve meters, and it would have this cabin that was six meters in diameter. That's not a whole lot, but he he did imagine that he would be able to use this ship as a rotating artificial gravity environment. Um we can talk later about exactly how feasible very small rotating artificial gravity environments are. The short

answer is not very um. So, coral Lev's dreams were severely limited by material and political constraints, and during the nineteen sixties he was forced to focus more on attempting to sort of match Apollo scale space projects UH and to work on weapons programs, of course, and so he also ended up proposing a tethered capsule based artificial gravity experiment, but it was never carried out, and coral Lev died in nineteen sixty six and the project was shut down.

What I mentioned this this tether system, the bolus, Right, You have two things attached by a tether and you rotate them against one another to see if you can generate a force. That kind of system was actually tried in space by the Americans. Now, if you'd asked me a few weeks ago, I think I would have thought that the nobody had ever carried out large scale artificial gravity experiments on or at least on the human scale

in space. I know they you know, they've centerfuged a few small animals and little contraptions, but I did not know there had ever been anything on the human scale. This experiment may count though it's it's a pretty weak attempt, but it wasn't attempt. I don't mean to say weak, like these astronauts and scientists didn't know what they were doing, but they didn't attempt all that much in terms of artificial gravity, right, I mean, it has will become clear

as you explain it. It's still like anything you do in orbit is pretty balls. Yeah. So this this definitely qualifies, but to your point in m it's not exactly a

robust exploration. Yeah. So this this is the Bullus method and it was tested to a to a very small extent during the Gemini eleven mission in nineteen sixty six, or as the people at the time would say, jiminy, and it was crewed by Charles Pete Conrad and Richard Gordon, and while in orbit around the Earth, the Gemini spacecraft was attached to a heavy counterweight object called the Agena Target Vehicle by h and that Agena target vehicle had

on it a thirty meter tether. Now, at the time, we didn't have these really good complicated robotic arms or auto locking cable jacks. To get these two objects connected via the tether, Richard Gordon, the crew member, had to leave the cabin in a space suit and attached the tether manually, and apparently this job was grueling. Gordon got so overexerted doing it that his life support system was stressed and he was sweating so much inside his space suit that he couldn't see out of his right eye.

Oh man, because I imagine it's just kind of like pulling up puddling up right, exactly like the dripping off the frozen in the lake at the bottom of Dante's Inferno, you know, Oh oh man, Yeah, wow, I never thought about. I had really not thought about, like the sweating in space and blinding yourself with your own tears horrible. But anyway, yes, sweating so much he blinded himself in his right eye. Anyway, he did manage to get the two spacecraft attached by

the tether. He got back inside the Gemini cabin and they were able to close the hatch and repressurize. Later after they were connected via the tether, the two spacecraft undocked from one another, so they disconnected except for the tether, and then they stretched out and pulled the tether taut and they began a rotation movement. And apparently it was hard to get this stable because they were what they called oscillations. I imagine that's like the tether being taught

but then loosening maybe or moving side to side. Um, there were ascilly sins in the rotation and for the first twenty minutes or so, and then after that the rotation rate was was increased, and the crew successfully managed to generate a tiny artificial gravity effect inside the Gemini eleven capsule. Uh. Supposedly, one way they measured this is somebody dropped a camera and it went in a straight line toward the floor, toward the outside wall of the

capsule that was away from where the tether was. So they measured it and figured that they had generated about zero point zero zero zero five G. And but that was with zero point fifteen revolutions per minute, So this is a very slow rotation. It's not a huge construct. Um. So, I mean, that's a reasonable thing to generate if they had been rotating faster, or if the tether had been longer, they might have been able to to create a more

powerful effect. But anyway, this did prove the principle and afterwards the tether was released and the edge in a vehicle was dropped to its orbital fate after about three hours. Now moving on, the author's also talk about how in nineteen eight there was this Slovene engineer named Herman Potasnik, writing under the pseudonym Herman Nerdung, who proposed a wheel shaped space station with habitation around the rim of the wheel.

And his idea was that you'd have this wheel that people would live in, and then the hub of the wheel you'd have a power generating station. And this would have been thirty meters in diameter. It was called the one rod or living wheel. And then in nineteen fifty three in Collier's Weekly, the German American rocket scientists Werner von Braun took this wheel shaped model and updated it

to be larger with a seventy six meter diameter. And von Braun calculated that if you had a wheel seventy six ms wide and it rotated at three revolutions per minute, you could simulate a gravity of zero point three G, which is sort of close to the gravity of Mars, which is zero point three a G. And this would make it suppose is a good training facility from ours expeditions, but also, as we were talking about earlier, might be

within livable tolerances for human life. You know, if if that's the best you could do in space, that might still be better than micro gravity, better than nothing at all, right, I mean, without without like actually doing any math on this, if you could make it to wear a really rigorous exercise regime for your space faring human if it allowed them to like could cleanly break even against you know, loss to to bone and muscle, then it would be

worth it, right, right. I mean, I'd imagine three hours of exercise a day and zero point three G does a lot more work than three hours of exercise a day and zero G. Yeah. And on top of that, you're getting acclimatized to the gravity that you're headed towards totally. Yeah. And so there have also been some really interesting proposed odd models, like in nineteen sixty four, Dandridge Cole and Donald Cox proposed this interesting idea. So Cole was really

interested in the mining and colonization of asteroids. And one of his proposed ideas was that you'd capture a large asteroid to be about thirty kilometers in length, that ideally to be an elliptical asteroid, kind of egg shaped, and you'd hollow out the inside of it, and then you would use propulsion to get the asteroid rotating along its major axis, and this would generate artificial gravity inside the hollowed out asteroid, and you could sort of build a

bubble city on the inside walls of the hollow space rocks, sustained by shining sunlight into the core with mirrors. This was also explored on the Expanse. By the way they talk about colon cox Um. I don't remember if they if they actually referenced them in any way, but there's they discussed, like the the early efforts to reach these various asteroids and to create a spin mine amount get them spinning and then you can build habitats inside them. Did it work or not work? I mean in the

knovel work. Okay, the only thing that didn't work in the novels was the colonization of Venus, like that ended up failing. They're trying to create like floating cities. Yeah, but anyway, Elsman, that could go really bad. Well anyway, so yeah, another weird idea this, Well it's actually maybe not that weird because here you get something like it. In two thousand one of Space Odyssey would be a sphere.

So the American physicist Gerard K. O'Neill proposed a rotating sphere that he called Island one and this would be five in diameter, would rotate once every thirty seconds, which he said would generate about one earth G at the equator. Now that's an important thing to consider a rotating sphere. It would be different than a rotating wheel, and that there'd be areas you could access that would not have

the same gravity. Right Like, if if you go to the equator, you'd get your maximum gravity, but then if you walk up to the poles of the rotating sphere, you'd basically be waitless because it wouldn't be a like a Hall Earth scenario where you would ideally have like the mass of the crust. Like the mass it's not going to play a part in this, So yeah, you would you would only experience the the maximum g's at that equator. Because again it's not actually due to gravity.

It's due to acceleration. R. It's due to your inertia against the constant angular acceleration of the rotating reference frame. Later that same guy, Gerard O'Neill, he proposed a larger model he called Island two and eventually this gigantic aluminum structure that came to be known as the O'Neill cylinder. And this would end up measuring more than thirty kilometers

long and three point two kilometers in radius. And you do this by rotating a little over once every two minutes, which could create earth gravity around the inside edges of the cylinder. And he envisioned this model would actually it would be like an Earth in space. It would contain natural landscapes that have forests and rivers and individual illages within. Yeah,

you'd have sunlight directed inside from external mirrors. I mean crazy stuff that there's a he had a book book, The High Frontier Human Colonies in Space, and the illustrations from this are just magnificent. I know you included one in in our notes for this this episode. Not trying to include some on the landing page for this episode

of Stuff to Blow your Mind dot Com. Because these are just gorgeous, gorgeous sci fi illustrations that really capture that sort of retro optimism for humanity's future beyond Earth. Why they kind of make me think of like Broigel or something. Yeah, yeah, I mean it's it's it's these just landscapes, you know, turned on their side and looped together to create this uh this this this internal rotating world. Yeah.

I'm not quite sure why, but this one illustration we've got included here, it reminds me of U. Broigel's landscape at the Fall of Icarus. Though I don't think you're to invoke chorus when contemplating such titanic feats of human achievement, and with so many lives at stake, it is a temptation of the gods to call down uh misfortune on

our hubris. And I mentioned the lives involved, because, for instance, in in O'Neill's Island one here he's talking about tens of thousands of people living inside there and uh, you know, a living there out their planet free lives and a

technological uh simulacrum of their home world environment. Anyway, you'll have to you have to look at the images that truly beautiful stuff totally and you can see in the images that, like the idea for the hollow asteroid, this would use huge windows and mirrors to shine sunlight inside for night and day cycles, which would be another thing that would be absolutely crucial if you're trying to fully

simulate an Earth environment. Now, I guess it's finally time to talk about probably the favorite model, the thing that everybody usually goes to, which is the Taurus. Yes it's the standard. Yes, it is the standard, and it is the standard from Stanford, the Stanford Taurus. So this is really the answer to what's most feasible, or at least

what scientists have concluded in the past. So in nine five, NASA and the American Society for Engineering Education put together a study comparing submitted designs for spacecraft habitats, and this was published by Johnson and Holbrow in nineteen and it looked at wheel shaped design, cylinder design, spherical designs, and NASA ultimately decided that a design submitted by Stanford students was the most feasible, and this was the design that

came to be known as the Stanford Taurus. So it Taurus is like we've been saying a ring, it's a hollow doughnut, and the Stanford Taurus would be a ring shaped tube. So it's a tube like a cylinder, except it's a tube that goes around in a circle and connects on itself a hollow donut. And so inside that tube it would be a hundred and thirty meters across.

Now keep in mind that's not the diameter of whole ring that's inside the tube that makes the ring, but the diameter of the whole thing would be about one point eight kilometers across, and then it would be the two would be about five point six kilometers long. So that would be the circumference and spinning the ring at one revolution per minute at these dimensions, it would generate about one G along the outer edge of the tube or earth gravity, and so feasibly you could build whole

earth environments inside, like the O'Neill cylinder. If this were built, you could supposedly have running water, farms, woods, all that kind of stuff to make a space habitat as lovely and wonderful as our natural earth habitat. And in the nineteen sixties and seventies, NASA did investigate ideas for creating artificial gravity environments for upcoming space missions. There's one illustration I found that I thought was pretty cool. I I don't know what the name of this is. I don't

know if it had a name. I'm calling it the Rod because it's also a rotating a station. But it's just a big rod. Now it's not rotating. It's not rotating, you know, like rolling as a rod. It's spinning, spinning baton, which I thought was interesting. So in nineteen sixty nine, the U. S Space Agency concept drawing for for this space station was produced. And I think it's an interesting concept, but obviously has you know, so it's got less material

investment than the construction of a huge wheel. But I would imagine it also has drawbacks. Like the farther you farther along you are towards the ends of the rod, the more gravity you experience, right, because gravity is a product of the speed of the rotation and the radius, And so as you go toward the center of the rod, you're shortening your radius, and as you go toward the outside of the rod, you're lengthening your radius, and so

at the center you'd be waitless. So I can imagine maybe something like this would be a system where the end compartments are again the places you go for your daily workouts in Earth gravity, the habitable zones really, yeah, to keep your your muscles and bones strong. And then the lower gravity environments would be I guess where you do other things. Maybe you sleep there, you know, I don't know, store stuff there or something like that. Or it's just where the captain gets to live, you know.

Everyone else has to float and deal with it. Yeah, And and this does draw on conceptually something that we see in science fiction a lot of the time, which is that maybe not the entire habitable portion of the of a spacecraft has artificial gravity. Maybe much of it is going to be a micro gravity environment where you're floating around, but there's like one room that's a rotating drum or taurists or something that you can go into

and there's artificial gravity and that one contained environment. Yeah. Now, in in Peter Watt's blind Side, if I remember correctly, here, there are portions of the ship that have artificial gravity via spin, but they're also working in even sweeping in the zero gravity area. I think so, yeah, I think so.

I think most of the ship, uh, if I recall, is going to be a zero gy environment where you're floating around, you have to propel yourself, and then there's one portion of the ship known as the drum that's the gravity environment. So there have been a lot of these propositions over the years. You know, NASA's looked at how to create space stations like this, but ultimately these designs would be extremely expensive to produce and difficult to

execute a little bit more on that later. But another factor is that you know, NASA's scientists are looking at this and they're saying, well, a lot of the experiments we want to carry out or microgravity experiments anyway. Right, So I don't know, do do we really need to spend all this money making the International Space Station UH an artificial gravity environment when people aren't going to be

spending their whole lives there. They're just gonna be there for a short period of time and then they're gonna come back and they'll be able to recover some of the negative health effects. Yeah, I mean noticed to two of the main points wrapped up in that we don't really need need um artificial gravity right now, not based on what we're currently doing. Yeah, and we're still there's still so much to learn about the effects of micro gravity on organisms right now, there's also still a lot

to learn about the effects of artificial gravity on organisms. Now,

if that's with the qualification, it's taught. What you're talking about there is the specific effects of centrifugal artificial gravity, because those are going to be somewhat different than just a pure, say, linear acceleration type artificial gravity that's going to be mostly indistinguishable from earth um in centrifugal environments, if you're in a spinning environment, depending on how small the radius is and how fast you're spinning, it could

have weird effects. And I'll talk about those complications in a minute. But so to study those weird effects, scientists have conducted uh experiments on animals like fish, rats, turtles, and generally animals seem to survive centerfuging in space just fine, though in systems with a very high rotation rate, rats seem to have a problem with orientation, movement, and vestibular

and motor coordination. So it's not a big surprise. But if you put them in a rotating centerfuge with a small radius and very fast rotation, you get some very dizzy and confused and uncomfortable rats. But on the plus side, the centerfuging process does appear to stave off the wasting effects of zero G. So if you put animals in a centerfuge like this, their bones and muscles do appear

to stay strong. Now, just to turn to one more recent proposition of an artificial gravity spacecraft, h I thought we should look at real quick at the Nautilus X. Apparently this is also the name of some vaping product, which is most of what the Google results are about, So God help us there. But uh, the Nautilus X was a proposed NASA spacecraft that would contain a rotating centerfuge. It would have a torus ring that was built to

simulate partial Earth G for the habitable quarters. And the spacecraft was designed but never built, and you can look up images of the design on the internet. It's kind of interesting to see. I think the idea is that part of it here would have this hollow doughnut that would be rotating and you could you could transfer its momentum to a flywheel and uh, and so it'd be rotating around the ship and you could get in there

to have some gravity time. And there have also been plenty of proposals over the years to add a centerfugure to the I S S in order to test artificial gravity. As far as I can tell, I don't think anything like that is still on the runway right now. I think these plans have pretty much stalled out. I don't know if you were able to across anything, but yeah, that was it seemed actually active right now. Yeah, but

there may be hope. So I don't know if you're out there working on a center fugure for the I S S and you think it might one day get up there, let us know. Well, you know, the turbo lift that I mentioned, like that news of it being funded, that's just this year. So it's possible that there's some additional initiatives that have been funded in the past couple of months. I hope they're not in competition. Would it be turbo latter versus centerfuge. It sounds like a great battle,

that's for sure. Now. I've mentioned several times the possible complications of a spinning artificial gravity environment, right you can sort of imagine that there might be some that's spinning around in a circle towards the floor. Is not going to be exactly the same as having a gravitational force pulling you toward the ground. It It might in most cases, or depending on the radius and the rotation rate, be mostly indistinguishable, but especially at smaller scales, there are going

to be some weird complications. This is gonna be the frozen from concentrate orange juice version of fresh orange juice. Yep, I think we should talk about the Coriolis force. So, Robert, imagine you're on a ferris wheel. You at home as well. Imagine you're up there. You're in the car on the ferris wheel, and you're just coming up over the top of the ferris wheel, and you notice that a friend of yours is directly below you, and you want to pour some mountain dew on their head, so you pour away.

You pour the mountain dew to hit your friend, but you miss, and the dew instead hits the people in the car directly behind your friend. And this really shouldn't surprise anybody, right, this is just duh. I mean, you're on a ferris wheel. Even though your friend was directly below you. When you began pouring the liquid straight straight down, the wheel was in motion, and by the time the liquid fell and reached the bottom. Your friend had moved

out of the way, and somebody else had moved in. Now, this is totally normal, totally intuitive physics on a ferris wheel because we're generally looking at a ferris wheel from

the outside. But if you try to imagine riding a rotating machine like a ferris wheel around in a circle in zero G in a closed environment, the rotation becomes your new stationary reference frame you the The whole idea is that you're supposed to be able to forget that you're rotating, and instead of feeling rotation, just feel a pull toward the floor. Like. Notice how even though your section of the Earth is orbiting the Sun and rotating

around the Earth's axis, everything seems perfectly still. Right, this is your inertial reference frame, And since everything around you is moving it roughly the same speed in the same direction, everything feels like it's holding still. And the same thing could happen inside a closed environment rotating into constant speed in direction in space, and so then the exact same trajectory we saw with pouring the liquid down from the top to the bottom of the ferris wheel still applies.

But because we're not looking in from the outside, it starts to look super odd, Like you could throw a packet of dehydrated space lasagna straight at somebody's face across the torus from or across the cylinder or whatever it is in this spaceship, and it would appear that even though you threw it straight, this thing you threw would suddenly arc over to the side, and so from your perspective, things would have this bizarre motion that wouldn't appear to

make any sense at all unless you were looking at the ship from the outside. Yeah. And there's actually a point in blind Side where they reference this where one individual throws it's either it's a ball or fruit or an apples. I think it's an apple, yeah yeah, and uh and it kind of goes wide. Yeah yeah, yeah, And this would be a problem. Now that might not be a big deal because you're like, well, how often

do you need to throw something to somebody? Well, actually, if you watch people in the International Space Station, they're sort of tossing stuff to each other a lot. Yeah, they're taking advantage of the microgravity. But it gets a lot worse than just tossing stuff to each other, because

this also is going to affect just general movement. If you're at a small enough scale, like if your radius is small enough and your rotations are fast enough, this is going to be affecting how your body itself moves. And it's even worse when you think about how it could affect, like affect your internal body systems. Yeah, I mean you could. You could find yourself in your chamber and no matter how how else the rest of you feels about your your your artificial gravity scenario, you might

feel a bit nauseous. The coreolis effects on inner ear, indo limp flow and on moving limbs creates a disorientation, nausea, vomiting, and even can cause loss of coordination. Yeah, and this actually isn't all that hard to understand because you've probably experienced something like this in your life, if you've ever been car sick while trying to read inside a moving car.

In both cases, what's going on is that the fluids inside your body are slashing around in directions that don't make sense to your eyes based on your environmental reference frame. So in a car, you're sitting in the car, you don't really feel like you're moving. You just kind of feel like, Okay, I'm sitting here stationary in a car, especially if you're reading or doing something with your eyes down, you're not getting the information in about movement around in

your environment. Meanwhile, the inside of your body, especially your inner ears, saying like whoa, we're all over the place, what's going on? And that discuss This discontinuity or disagreement between the movement information supplied by your senses and felt by your inner ear causes this destabilizing sensation. It makes

you sick. Now. One of the issues here that we keep coming back to is that the smaller you're rotating environment, the more it is actually a carnival ride, and that the larger it is, uh, the better chance you have it's smoothing some of the more undesirable effects out exactly right. So if you, I mean, one thing you'll notice is that, like, there are Coreolis effects in the rotation of the earth, right,

but normally comes up in aviation. Yeah, if you throw a baseball, if you are just standing around, like, the Coreolis effect of the rotation of the Earth is not messing with you too bad because the Earth is huge. Um, if you if you're in a much smaller rotating reference frame, it would be messing with you a lot more. I mean, mainly on Earth, you only see the rotation of the Earth causing Coreola's forces to affect a large scale movement such as like tides and weather patterns, you know, huge

movements over long distances and long time. Yeah, and so the same would be generally true in an artificial gravity environment that was rotating, if it was a very very big radius and a slow rotation. In this environment, the Coriolis forces would be much less likely to have a noticeable effect on your body and on the stuff you're doing. Another side effect, especially of a small radius fast rotation system, would be in a rotating environment, you could have unequal

gravity loading. That's about as weird as it sounds. So the centrifugal force you feel, like we were saying, is partially determined by your distance from the hub. So in a big wheel, this isn't it's not gonna matter very much. You know, the percent distance from the hub between your head and your feet, if the hub is hundreds and hundreds of meters away, is just you know, it's just

not that much. If it it's ten meters away, then suddenly you might start to feel a significant difference between the gravity affecting your feet and the gravity affecting your head, and this could affect it could lead to problems with things like circulation. But it would also just be disorienting and make movement difficult, partially negating the benefits of artificial gravity. Another reason that if we were going to make one of these things and it was to be effective, it

would need to be very big. And that is the answer to one of our final questions. Here at the end, you're saying, Okay, so we know basically that we could make some form of artificial gravity sort of work. I mean, it might not be perfect, but this is you know, basic physics. This is not something that's totally hypothetical. It could work, So why haven't we done it? The main issue is size and cost. For a spinning artificial gravity environment to be tolerable to human occupants, it would need

to be pretty big. And to be that big, you would need lots of construction materials. And to get lots of construction materials into space, you need a lot of rocket launches, and rocket launches are very expensive. They're getting cheaper, but they're still very expensive For the tons of materials you need to get up there to build this stuff. So it really at this point is mainly a matter of cost, right, And I mean you can basically any uh,

any space mission, any space initiative. I mean, they're going to be priorities, and you can even if if something like this is on the list, it's going to get pushed down by other initiatives. Yeah, yeah, totally. And I mean, so building a one of these big, functioning artificial gravity environments that would be something habitable, generating something close to Earth g could fit a lot of people on it, You're you're probably talking about just a multi trillion dollar

project here. It would just be so huge it's kind of not feasible for Earth space programs at the investment levels they're encountering. Now here's another problem. We've got some limits on research. Right. Ideally, if you're gonna launch one of these things in space, you'd want to do a lot of preparation research up front to make sure you're not making a big mistake about what what's the best

thing to do in space? But on Earth, there's really no feasible way to perfectly test out artificial gravity concepts because on the surface of the Earth you have to deal with the constant complications of Earth gravity. So you

can kind of try to simulate weightlessness. And so you could do like neutral buoyancy experiments, you know, where you're in water with a sort of balanced out buoyancy weight ratio, or you could do you could get in an airplane and do parabolic flights to have you know, twenty five seconds at a time or so of weightlessness. But these things aren't all that helpful when you're talking about trying to test out an artificial gravity environment at a like

ship or space station size scale. Yeah, you really need a nothing eg. Zero G micro g environment and to get that you have to go into space. You have to go to orbit, right, So to really test one of these things, you essentially have to do it. You can't really test it without just making this thing and putting it in space. Now, I guess the good news is that it's kind of tom to to sort of reference the old Mitch Hedberg a bit about about an escalator.

What do you call it? Broken escalator? It's stairs, right, Um, is like if the thing didn't work, you just turn it off and you float. I guess right, Like it's still going to be serviceable. On some level, and you can imagine that. I can imagine a scenario. Maybe they've even done this in a sci fi where you have like a non functional tourists space station where people arriving like, hey, what's with the walls? How come? How come this thing didn't work? Well, it's it's it. We're working on it.

We gotta work out the kinks, so it's not fully functional yet, right yeah, yeah, And the people could complain. They'd be like, oh, but I'm I'm experiencing space sickness. And you'd have to be like, hey, look, it's not as bad as the coreolas sickness. Or it's a or it's a hotel where you have various rotating modules are rotating wings the hotel, and like, I'm sorry, all the all the rotating rooms are taken, all our gravity books. Sorry, we've only got smoking rooms or smoking and micro gravity.

That's it. Sorry. Uh. But so hey, we're saying why it's going to be a problem, uh to to build these environments. But we don't want to end on a downer, because I've got something optimistic to say. To revisit a comment we made earlier. If you're willing to limit your ambitions, artificial gravity starts looking a lot more achievable. If only a small part of your spacecraft needs gravity, or if you're willing to settle for significantly less than Earth gravity,

you've got a lot more options, right. For example, the rotating sphere compartment in two thousand one of Space Odyssey, they say it produces only about the gravity of the surface of the Moon. That's not a lot, but it might be enough that you can sort of jog like the character does. Basically, it's better than nothing. Things still fall towards the floor, even if it's not quite like

being on Earth. And we mentioned some of those tests earlier, tests on human subjects in the night teen sixties in these parabolic flights to basically determine what was tolerable or acceptable to people, you know, and they found out that zero point two G is actually a lot better than zero point one G. So there's like a pretty steep drop off point about what's acceptable somewhere in that range that normal human activities were mostly doable starting it about

zero point two G. At about zero point five G once you get to half of Earth gravity, subjects felt about as sure of their movements as they did at one g. So once you're halfway there, it's basically good enough to do your movements and you know, maybe even sleep better at night. Yeah, all right, so there you have it. Artificial gravity. Uh, not to be confused with anti gravity. That's an entirely different podcast there. Now, how many times did we accidentally say anti gravity in this

episode today? None that I know of, but there could be. How many are going to catch later? I kept catching myself doing it in the note It's I kept I kept typing in um anti gravity, and I have to go back and it was like, not anti gravity because anti gravity is sort of sort of even though it's fun and science fiction as well, it's sort of a dirty word in scientific research. There are other terms that you would use. But but again that's a that's a

topic for another time. If you guys want to discuss anti gravity, we can do that in a later date. Anti gravity it's actually fairly simple. It's commonly known as jumping and lifting. All right, Well, don't spoil it all, don't blow it all, Joe. Alright, So hey, if you wanna listen to more episodes of Stuff to Blow your mind, you want to explore past episodes and we have a bunch of them, many of which deal with space and space exploration. Head on over to stuff to Blow your

Mind dot com That is the mothership. Are are spinning mothership there and you will find uh a boarded UH post blog posts, podcast episodes, videos, links out to our verious social media accounts that just Facebook, Twitter, Tumbler, Instagram.

We're on all of those. Hunt us down, follow us, and if you listen to us on on Apple Podcasts or any other podcast system out there, leave us a nice review if you have the ability to do so, because that will help tweak the algorithm in our favorite and allow us to continue to bring great episodes like this to your year olds. Andy, And if you want to get on that mothership with us and get a little bit sick, you can always email us and blow the mind at how stuff works dot com for more

on this and thousands of other topics. Does it how stuff works dot com