From the Vault: Artificial Gravity

Episode Transcript
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Speaker 1 (00:05):
Hey, welcome to Stuff to Blow your mind. My name
is Robert Lamb and I'm Joe McCormick, and it's Saturday.
Time to venture into the Vault. This episode originally aired
on July and it is about artificial gravity. Yeah, this
is a really fun episode. Uh, and it's and I
think it's a great one to to re air here
as our last Vault episode of But it gets into

(00:28):
various models for how we could conceivably carry out artificial
gravity aboard us some sort of an artificial vessel. Now,
why did you think this would be a great last
Vault episode of the year. Is that that you expect
to be floating around the end of December or what? Well, yeah,
I guess you know your New Year's Eve celebrations, everybody's

(00:49):
going to feel a little floaty, feel yourself or maybe
you're gonna feel more drawn to the year. I hope
everyone's gonna feel a little lighter. You need some centrifugal anchoring.
That's the other thing. People are may very well feel
like they've been spun around in some sort of human
concoction and uh, and they're struggling to to keep their
feet underneath them. That's going to be the new trendy
hangover cure. Just get inside your high efficiency washing machine. Absolutely,

(01:13):
but yeah, this is a great episode. We get to
talk about a number of sci fi properties. We talk
a little bit about two thousand and one of Space Odyssey.
Uh so, hey, everyone, enjoy and we'll catch you on
the other side. Welcome to Stuff to Blow your Mind
from how Stuff Works dot Com. Hey you, welcome to

(01:39):
Stuff to Blow your Mind. My name is Robert Lamb
and I'm Joe McCormick. And Robert, I know that many
times you must have imagined what life is like in
a zero gravity environment, right, Oh yeah, I mean you
can't help you, You can't help thinking about it as
you read about space exploration and and engage with with
various science fiction scenarios. What would it be like to

(02:01):
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 problem,

(02:23):
space sickness once they arrive that might go away after
some time, 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

(02:44):
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,

(03:05):
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 our 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 That's where the

(03:26):
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

(03:47):
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

(04:08):
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 jammed up, Like you can't
taste things the way you normally would and part of

(04:30):
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 A Packing

(04:51):
for Mars. If you're in a microgravity zero gravity environment,
your bladder doesn't fill up from the bottom up would
feel 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

(05:12):
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 then, there would
be a thing that would be like a p quote emergency.
Remember the emergency? Oh yeah, well, I mean I guess

(05:33):
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 off the front
door is closer to him, uh, you know, grabbing himself
the whole time and going I gotta go pee and
then immediately paying Um. This is the kind of thing
adults tend not to experience, unless perhaps you go into space. Right,

(05:58):
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

(06:22):
have to exercise constantly when they're in microgravity environments. They've
got to 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.
I mean, they still come back to back to Earth
messed up, and they need time to re reacclimate. Hopefully

(06:44):
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
drinks at the 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

(07:07):
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 you're like, oh,
that's enough of that. I'm good. An astronaut a person
it'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,

(07:29):
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 Done here, but
they're they're both prime examples because they're straight into the blender,

(07:52):
right 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

(08:16):
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 in in in in Dune. You have the

(08:36):
the Holtzman effect generated by the Holtzman 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

(08:57):
stories you want to tell. You know, I'm okay with
that be 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,

(09:19):
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 slack. Yeah,
I'm fine with some magic anti gravity. Now, in terms
of sci fi properties that do take it really seriously.

(09:41):
What are what are a few films that come to mind? Well,
of course, you you immediately think of two thousand 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

(10:01):
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

(10:23):
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 that're gonna we're gonna be discussing today.

(10:44):
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

(11:06):
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 in the program,
I think a lot of our science fiction are sci
fi ships are essentially seagoing vessels and tales of seagoing
vessels and seagoing captains, uh, taken from Earth and transposed

(11:29):
into space. I mean that was basically Gene Roddenberry's a
whole deal with Star Trek that it was was the
Master and Commander books that he wasn't No, it was
a different one. Um. I can't remember the series offhand,
but anyway, he was inspired by by literary tales of
of of adventurous humans at sea. Uh no, well maybe

(11:51):
I don't know. Well I guess is yeah, from Hell's Hired.
I stabbed at the right. But it's it's more difficult
with linear acceleration because you have to 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,

(12:14):
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

(12:36):
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 space ships, for

(12:58):
things like that. Now. Off 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 space time how to curve, and that the
curvature of space time tells matter how to move right
So let's start with mask because I think that's the

(13:19):
that's that's the essential part. That's that's a pretty easy
to understand here. So everything with mass, from a dust
moat 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 opect can
pull in objects from across the vast distance. Right, And

(13:41):
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.

(14:01):
Things are attracted to each other, eventually becoming stars, planets
all that. Yeah, And then alert 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.

(14:25):
It was one of the first big 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

(14:47):
passed close to our Sun. Yeah. And similarly, the less
gravity there is, the slower time passes. And this is
a phenomenonme is gravitational time dilation. 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

(15:07):
you saw that. We mentioned the movie Interstellar earlier. There's
actually 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,

(15:29):
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

(15:51):
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 this whole hypothesis comes

(16:12):
together because quantum theory, to refresh, addresses how the universe
works at the smallest subotanic levels, and the resulting model
here does not explain gravity. So gravitons and the theory
of quantum gravity is an attempt to reconcile general relativity
with quantum theory. It's a basically an attempt to patch

(16:32):
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.

(16:55):
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

(17:15):
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

(17:36):
couldn't find any, like, any real theories about how gravitons,
if they 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 handwaving magic. Right. So we come back
to mass, then yeah, you could, I guess, have a

(17:58):
spaceship that's as massive as the Earth, and then that
would have that would give you the gravitational pool you 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

(18:19):
ship to take us there, to see if we can
build a structure around the Sun that will reflect some
of its radiation 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 Scatow thruster. Essentially, it would just

(18:41):
drive the sun. Yeah. That actually features into No Surprise
and Ena 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.

(19:01):
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 mass of Earth. Right, And
if you can do that, then, uh, I mean you're
already you're already a pretty powerful civilization. I'm not sure
where you would rank on the Cardassi of scale, but

(19:23):
you'd be you'd be potent. That'd be definitely a Cardassi
of one, maybe a Cardassi of two. All Right, 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,

(19:46):
but in a but in a real sense. Yeah, and
and 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

(20:09):
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

(20:31):
the difference between these two situations. And so knowing this,
we could 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 than alright, we're back.
So The first model of artificial gravity we're going to

(20:51):
discuss here is the one that I alluded to earlier
and discussing the expanse, and one that I think by
and large, bab, 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?

(21:13):
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,

(21:37):
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

(22:00):
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

(22:20):
long flight space craft, it was built in the office
tower configuration. Each deck one floor of the building. Ladders
or 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

(22:42):
description for it. Each compartment within the massive rings was
built on a swivel system that allowed the chambers to
re orient 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

(23:05):
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

(23:25):
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,

(23:47):
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 imagine 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

(24:08):
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, I mean we
we see the required propulsion at work when a chemical
rocket creates enough for us to counter this gravitational pull
and achieve escape velocity. But they're only achieving it from
a matter of seconds or minutes. For our spaceship here

(24:31):
are theoretical spaceship, our office building on its side, you'd
need something more constant. So, just to refresh on the
g's 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,

(24:52):
like you said, to exert a constant one G. Yeah.
So one of uh, the sources we turned to for
this was a wonderful too thousand seven book Artificial Gravity,
edited by Giles Climate and Angelie Buckley, And there's an
article in there by Buckley, Climate and William Pulaski of

(25:12):
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 days, depending on the distance. I
mean that would be you'd have to have incredible power, yes,

(25:35):
incredible thrust to like a powerful fuel to accelerate that much. Also,
I'm how did so do 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,

(25:58):
Or you'd have to have some sort of like an
intern habitat that's like a capsule on that rotates. 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 hundred and

(26:21):
fifty million miles with the Sun between the two. So
I guess that's not doable in two to five days.
The yeah, 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.

(26:45):
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

(27:06):
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 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

(27:28):
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
posted 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

(27:48):
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 a
lot of speculative properties that I enjoy. Sometimes there'll be
something completely ridiculous, uh, something completely magical, But then you
discuss all the real world ways it might play out.

(28:11):
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, without really getting bogged down in the fact
that zombies are are kind of a dumb I can't
actually exist. But it's like, roll with me. Zombies are real.

(28:34):
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 rabies. I mean we don't have rabies,
but there is you never know, alright, so you're probably wondering. Okay,

(28:58):
we've established how this would work with talked a little
about the sci fi, but what kind of work has
actually gone into testing it. Well, there'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 Night

(29:20):
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 the

(29:42):
chair swivels, and you have somebody strapped into the chair
with a bunch of you know, electronic dude 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 can traption, isn't it? Yes, it
it does. It looks very Terry Gilliam. Now they tried

(30:04):
this out and it peaks speeds. It only provided point
to G and according to a Clemon 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.

(30:25):
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?

(30:46):
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 coma
pace a board your spaceship and trick them into thinking
that there's still on Earth. Like that's a tricker scenario.
I mean, maybe you could do it by telling them

(31:07):
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 Clement 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

(31:28):
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's

(31:52):
Saturn is one point of seven GES. Guess they're not
going to be standing on the surfaces of Neptune or
but we have stood on the surface of the Moon,
which is point one six Geese 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. Yeah, can

(32:14):
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 stumbles, and
a number of these stemmed from the inability to evaluate
terrain slope. Yeah, again, like you can't tell the difference
between uphill and downhill. It's hard to imagine. Yeah, and

(32:36):
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 turbo lator. Yeah, and this, Uh. The idea here

(33:00):
is to combat the effects of micro gravity 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.

(33:21):
It would, theoretically, according to 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

(33:43):
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 capsule here, and we're gonna you back and
forth for however long you're treatment last. The flipping bullet. Yeah, Now,

(34:06):
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.

(34:27):
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

(34:49):
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 to one of these and shoot
them back and forth to to keep their need to
avoid any debilitating effects involved with their space travel. But
of course for that to work, you have to have

(35:10):
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 there. You have to be able to produce that effect. Uh,
you have to always be on your way somewhere or

(35:32):
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, that's 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

(35:54):
acceleration as possible is good. Uh, it's still I guess
I have the question of 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

(36:17):
we have in the 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,

(36:41):
that's linear acceleration for you. That's one model. We're going
to 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
tow us, the double Taurus. All these different models were
of course talking about uh, the manipulation of centripetal force.

(37:06):
Than 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.

(37:27):
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 the 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

(37:47):
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 uh, 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

(38:09):
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, i'd 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

(38:32):
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

(38:54):
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 force sensation
generated by inertia to simulate gravity. It's your body's inertia

(39:18):
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 centrifugal 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

(39:38):
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 hell the

(40:00):
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

(40:23):
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 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

(40:47):
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 key 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

(41:09):
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.

(41:32):
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

(41:54):
the intuitive physics of this on your body, just in
your imagination. If you've ever done the carnival ride where
you get on the what is it the cyclotron, the
circula 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

(42:16):
you around very fast, and suddenly you're just pinned to
the back wall. 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,

(42:38):
but but I have written a 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 on I ride. But oh interesting,
uh well it's also yeah, this the centripetal centrifical force.

(43:00):
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

(43:23):
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

(43:44):
and the loop to 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 simulates
something within the realm of one g or one of
these fractions of one g that seemed like they might

(44:05):
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

(44:27):
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,

(44:49):
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,

(45:10):
which is like a wheel. So you'd have a donut,
and inside the doughnut it's hollow, and people are walking
around on the outer wall of the inside of the
hollow donut. This would be the taurus 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

(45:32):
to see it in space, uh, you know, 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 seeling 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

(45:54):
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

(46:15):
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 set 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

(46:36):
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 flying out of either orifice. Right,
So you're saying, like, if you had to perform the
Heimlich maneuver on a fellow astronaut, they might cough up
a bolus of food they've been choking on while you're

(46:58):
in the bullus. Yeah, and then of course that all
so read. Uh. I think I've read in like space
manuals about uh using the toilet in space, they refer
to the fecal bolus really, 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

(47:20):
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.

(47:41):
This would be the chapter on the history of artificial gravity,
and that's again in that book by U 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 Constantin L. Tilkowski, who lived
from eighteen fifty seven and nineteen thirty five. And Tiolkowsky

(48:04):
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 test out the effects of

(48:28):
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 of which translates to free Space
in eighteen eighty three, Tiolkowsky sketched a hypothetical spacecraft and
designed how you could spin a spaceship to give it

(48:51):
artificial gravity on the outward facing walls. Another pioneer who
would be Sergey Kralv, one of the great minds behind
the Soviet space program. He was a really vicious 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

(49:13):
fifty nine. This was before Uri Gagarin's first spaceflight 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 uh, this 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

(49:35):
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.

(49:55):
The short answer is not very um. So coral Lev's
during 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

(50:19):
gravity experiment, but it was never carried out and coral
Lev died in nineteen sixty six and the project was
shut down. But I mentioned this, this tethered 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

(50:40):
a few weeks ago, I think I would have thought
that that 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 centrifuged 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,

(51:04):
but it was an attempt. I don't mean to say
week 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 so
this this definitely qualifies. But to your point in might
it's not exactly a robust exploration. Yeah. So this this

(51:27):
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

(51:47):
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
botic arms or auto locking cable jack's. To get these
two objects connected via the tether, Richard Gordon, the crew member,

(52:08):
had to leave the cabin in a space suit and
attach 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

(52:31):
dripping off 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 the
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

(52:52):
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, or 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

(53:14):
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
oscillations 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

(53:36):
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 row point

(54:00):
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 to create a more powerful effect.
But anyway, this did prove the principle. And afterwards the

(54:21):
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 nor Dung, who proposed a wheel
shaped space station with habitation around the rim of the wheel.

(54:44):
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

(55:06):
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 h G. And this would
make it supposedly a good training facility from Mars expeditions,

(55:29):
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 really rigorous exercise

(55:50):
regime for your space faring human if it allowed them
to like to cleanly break even against you know, loss
to to bone in 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,

(56:10):
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 Coal and Donald Cox proposed
this interesting idea. So Coal was really interested in the
mining and colonization of asteroids, and one of his proposed

(56:31):
ideas was that you'd capture a large asteroid to be
about thirty kilometers in length, that ideally 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

(56:52):
could sort of build a bubble city on the inside
walls of the hollow space rocks, sustained by shining sunlight
into the core with rors. 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

(57:14):
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 in the knovel The Toll it worked. Yeah, okay, yeah.
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, elm,

(57:37):
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. Yeah, so
the American physicist Gerard K. O'Neill proposed a rotating sphere
that he called Island one. And this would be five
in diameter, rotate once every thirty second, which he said

(58:00):
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

(58:22):
be waitless because it wouldn't be a like a hollow
Earth scenario where you would ideally have like the mass
of the crust. Like a mass is not going to
play a part in this, So yeah, you would. You
would only experience the the maximum GS at that equator
because again it's not actually due to gravity, is due

(58:43):
to acceleration, right, 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

(59:06):
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 villages within. Yeah,

(59:28):
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

(59:48):
are just gorgeous, gorgeous sci fi illustrations that really capture
that sort of retro optimism for humanity's future beyond Earth.
Why did 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

(01:00:09):
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
uh Brogel's landscape with the Fall of Icarus. Though I
don't think you're you're allowed to invoke Icarus when contemplating

(01:00:29):
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 In
O'Neill's Island one. Here he's talking about tens of thousands
of people living inside there and uh you know, a

(01:00:51):
living there out their planet free lives and a technological
uh semilacrum of their home world environment. Anyway, you will
have to 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

(01:01:13):
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. It's the standard, Yes, it is the standard,
and it is the standard from Stanford, the Stanford Taurus.

(01:01:33):
So this is really the answer to what's most feasible,
or at least what scientists have concluded in the past.
So in ve 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 nine
and it looked at wheel shaped design, cylinder design, spherical designs,

(01:01:56):
and NASA ultimately decided that a design submitted by stand
Ford 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

(01:02:17):
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 the
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

(01:02:37):
the tube 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

(01:02:57):
were built, you could supposedly have running wall or 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.

(01:03:18):
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 space 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

(01:03:39):
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 it 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 raw odd, the more gravity you experience, right,

(01:04:03):
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 towards 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

(01:04:24):
you go for your daily workouts in earth gravity, ha, Yeah,
to keep your your muscles and bones strong. And then
the lower gravity environments would be I guess we'd do
other things. Maybe you'd 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

(01:04:45):
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 your flow around,
but there's like one room that's a rotating drum or
taurists or something that you can go into and there's

(01:05:07):
artificial gravity, and that one contained environment yeah. Now in
in Peter Watt's blind side, Yes, if I remember correctly,
here there are portions of the ship that have artificial
gravity DA spin, Yes, but they're also working and even
sleeping in the zero gravity are I think so? Yeah?
I think so. I think most of the ship, if

(01:05:29):
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
has looked at how to create space stations like this,
but ultimately these designs would be extremely expensive to produce

(01:05:50):
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

(01:06:12):
an artificial gravity environment when people are 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 the
negative health effects. Yeah. I mean there's two two of
the main points wrapped up in that we don't really
need um artificial gravity right now, not based on what
we're currently doing. Yeah, and we're still there's still so

(01:06:33):
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,

(01:06:55):
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

(01:07:18):
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

(01:07:41):
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 proposity, ession of
an artificial gravity spacecraft, h I thought we should look

(01:08:03):
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 TURUS ring that was built to simulate partial
Earth G for the habitable quarters. And this spacecraft was

(01:08:25):
designed but never built, And you can look up images
of the design on the Internet. It's kind of interesting
to see and 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 would be
rotating around the ship and you could get in there
to have some gravity time. And there have also been

(01:08:47):
plenty of proposals over the years to add a centerfuge
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. And I
don't know if you were able to do across anything.
But yeah, that was that 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

(01:09:08):
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 later versus centerfuge. Oh, it sounds

(01:09:31):
like a great battle. That's just 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 towards the ground. It it

(01:09:52):
might in most cases, or depending on the radius and
the rotation rate, be mostly indistinguishable, but especially it's smaller scales,
there are gonna 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

(01:10:13):
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,

(01:10:34):
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

(01:10:54):
liquid straight straight down, the wheel was in motion, and
by the time the liquid fell and reach 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

(01:11:18):
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.

(01:11:38):
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 in a constant and speed in direction

(01:12:01):
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

(01:12:21):
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

(01:12:41):
ship from the outside. Yeah, and there's actually a point
in Blindside where they referenced 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

(01:13:02):
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

(01:13:23):
to be affecting how your body itself moves. And it
gets 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 into limp

(01:13:45):
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

(01:14:09):
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 about movement around in your environment. Meanwhile,
the inside of your body, especially your inner ears, saying

(01:14:31):
like whoa, We're all over the place, what's going on?
And that discus 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

(01:14:52):
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 Coriolis effects in the rotation of the Earth, right,
but normally come yeah, if you throw a baseball, if

(01:15:14):
you are just standing around, like, the Coriolis effect of
the rotation of the Earth is not messing with you
too bad because the Earth is huge. Um, if you
if you were 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

(01:15:35):
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

(01:16:00):
end 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

(01:16:21):
hundreds and hundreds of meters away, is just you know,
it's just not that much. If 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

(01:16:43):
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 for of artificial gravity
sort of work. I mean, it might not be perfect,

(01:17:03):
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 spending 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

(01:17:25):
need lots 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 any space mission, any space initiative. I mean,
they're going to be priorities, and you can even if

(01:17:48):
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

(01:18:09):
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

(01:18:29):
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,

(01:18:50):
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

(01:19:13):
really need enough in 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 to to to sort
of reference the old Mitch Hedberg a bit about about

(01:19:35):
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

(01:19:56):
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 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 Coreoli's sickness, or it's
a or it's a hotel. We have various rotating modules

(01:20:18):
or rotating wings the hotel, and like, I'm sorry, all
the all the rotating rooms are taken, all our gravity
rooms are booked. 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

(01:20:40):
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.

(01:21:03):
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. Uh. 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

(01:21:23):
those tests earlier, tests on human subjects in the nineteen
sixties and 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

(01:21:48):
at 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

(01:22:10):
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. Doesn't how many are later? I kept catching
myself doing it in the notes. I kept I kept
typing in um anti gravity, and I have to go
back and it was like, not anti gravity because anti

(01:22:32):
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.

(01:22:56):
All right, Well, don't spoil it all, don't spoil it all,
joke alright. So hey, if you want to 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.
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(01:23:18):
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(01:23:39):
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(01:24:03):
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.css-14f5ked{margin:0;word-break:break-word;display:-webkit-box;-webkit-box-orient:vertical;box-orient:vertical;-webkit-line-clamp:2;overflow:hidden;}From the Vault: Artificial Gravity