What Is A Space Elevator?

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Episode Transcript

Speaker 1 (00:08):
Hey, Daniel, did you ever think about being an astronaut?
I always wanted to be an astronaut from some points
of view, like I wanted to be out in space.
I wanted to see the stars, I wanted to see
the Earth under me. But I was also sort of
terrified of getting up there. It's really extremely difficult. Like
I talked to an astronaut at last year and he
said it was like writing the tip of an explosion

(00:28):
to be on a rocket, and that scares me. I mean,
especially after the Challenger disaster. You know, that was very
vivid in my mind when I was a kid. It
seems terrifying and it seems dangerous, and it is. You know,
you're you're it's just basically you strapped to a rocket,
you know. Yeah, it's you're literally writing an explosion. You're
like surfing a fireball. But would you want to go

(00:50):
to space if it was easier? Yeah? I think so.
You know, if you could just like, um, you know,
get in your car and say, take me to space
or something like that series take me to Space, Google
Directions to Space. Please. Well, what if it was just
as easy as getting into an elevator and then pressing
the space button. I think I would sign up for that. Yeah,

(01:12):
que the elevator music. Hey guys, this is Jorge and
I'm Daniel, and welcome to our podcast, Daniel and Jorge

(01:34):
Explain the Universe, a production of I Heart Radio, in
which we take crazy stuff in the universe, including stuff
people want to make, and explain it to you. Break
it down, make sure you can understand the next time
you're at a party and wanting to impress your friends
with your cool science knowledge. That's right, all the crazy
ideas out there in the universe and the cosmos, and
all the crazy ideas in people's heads that may or

(01:56):
may not be possible. That's right. I'm a particle physic
this and I'm cartoonist. And together we wrote a book
called We Have No Idea, which explores all the mysteries
of the unknown and the things we don't know about
the universe. And together, twice a week we try to
take you up into space and out into the cosmos.
And and today we're going to talk about a very
interesting idea that's been out there floating in science and

(02:19):
engineering circles and definitely on the internet, which is a
pretty interesting and different way to get to space, yeah,
which is really fascinating because it seems like we're sort
of trapped on Earth. You know, gravity keeps us here.
We've talked a lot about how gravity deforms space and
makes it difficult to get off of Earth. And it's
nice that gravity holds you down to Earth, but sometimes

(02:40):
you want to get up to space. You know, if
if humanity wants to explore the stars and build space
technology and space industry and space habitats, then eventually we've
got to get off of this planet. And so we've
got to somehow counteract that gravity and climb up into space. Yeah,
And the main way we've been doing that so far
is by trapping ourselves into a giant too full of

(03:03):
flammable gasoline or or hydracine or rocket feel and then
lighting that up and hoping that the explosion kind of
takes us up into space. It's basically the high tech
equivalent of taping a bunch of fireworks to your nie,
to your legs and setting them off, right, which we
advise our listeners not to do, or sure writing writing

(03:26):
the shock wave from a bomb on your surface or something, right,
it sounds like a bad idea. Yeah, it's carefully channeled explosions.
But there might be a different way to get to space.
And this is a pretty interesting idea because I feel
like it's the kind of idea a six year old
would come up with, Like, if you have six year old, Hey,
how do you get to space? This is what they
might come up with. Oh my god. I totally should

(03:47):
have done that. I should have gone to a kindergarten
classroom and said what's the best way to get the space.
I would have gotten some awesome ideas like the moon
and climb up the rope or something like that. Yeah,
probably you get a lot of just use the spaceship
the jump really hard. Now, today's topic on the podcast

(04:07):
is space elevators. Are they possible? How do they work?
How would they work? Should you ride in one? What
should you pack? What's the protocol for when you're standing
in a space elevator? Do you make eye contact? Do
you go to the furthest opposite corner of an elevator?

(04:31):
Do you say, oh wait, I'll take the next one? Yeah?
Do you not and do the what's up? Or have
a good time? When they leave these say have a
good day? What do you? What do you what's the protocol.
I don't know, but you know, if we do develop
space elevators would be a whole impact on culturing. That
people will meet and fall in love on space elevators right,
become um an element in fiction. You'll see them in
movies and comic books. Yeah, it's a pretty fascinating idea

(04:55):
and just the concept of elevators. Um, you have a
favorite elevator, right, Daniel, I do have a favorite elevator.
I love that in Europe when you get into an elevator,
the ground floor is listed as zero for some reason
that just like tickles the nerd in me. And at
the Large Hadron Collider, the experiments are deep, deep underground,
rather like a hundred meters underground, so that the radiation

(05:16):
produced in the collisions doesn't effect anybody above ground. And
so they have this elevator you can take down into
the tunnel where the accelerator is and that the collisions happen.
And it just has two buttons. One of them says
zero for the ground level and the other one says
minus one, and so you press you go whooh down
a hundred meters, which is you know, really far deep

(05:37):
deep into the ground. Um. So that one's really fun.
There are two options zero and minus one. Yeah, exactly. Um,
there's a much there's a much more dramatic elevator and
some other physics experiments like in the snow Lab in Canada.
They go, I think miles underground because they have their
their experiments underground in a mind like an old abandoned mine.

(05:58):
Did I ever tell you I have written the sir
and elevator down to the bottom? You have? Really? How
did you did you sneak in? Did you pass the
retin retinal scanner? Or did you go say I'm a
physics ninja. I remember you're not the physics ninja was
trying to take credit. Now, how did you get in?
Did you know I got I was getting a tour
and uh I went down there and it was super exciting,

(06:20):
super fun. I didn't get to walk the tunnels, um,
but I was. I was kind of disappointed to see
that the one comic strip that was up on the
walls there was an x k CD comic strip. Did
you take it down and replace it with one of yours? No?
It was a well earned it was a really funny
comic muse. Well, so, yeah, so getting to space is

(06:42):
really expensive, right, and so the idea that you might
be able to take an elevator sounds pretty appealing. Yeah,
it's really interesting how why getting the space is so expensive?
You might think, like, what's the big deal? You just
build a rocket and you shoot it up there? Right,
how expensive could rocket fuel be? Ye? Right? But the
problem is that you need a huge amount of fuel
to get to space, and you can't refuel a rocket

(07:03):
along the way, right. You have to lift all the
fuel you're gonna need, um from the beginning. Yeah, yeah,
I saw this presentation by an austronaut ones who said
that basically ninety five of your rocket, like by weight,
like the weight of your rocket is basically fuel. Yeah, exactly.
Imagine if you were going to drive across the country,
but there were no gas stations between here and there,

(07:26):
and so you need to like pack all the fuel. Right,
So you have a huge tanker and you fill it
with fuel. So now you need extra fuel to bring
that fuel, right, and so pretty soon you're carrying like
a train of tankers with you. And so you're right,
most of the fuels they're just to lift the other fuel. Yeah,
so a lot of your your fuel just goes to
lifting the fuel that you need to lift the other

(07:48):
fuel to maybe a little bit use some of that
to lift you up. Yeah, exactly, it's diminishing returns. Every
pound of fuel you add, a very very small amount
of it actually lifts you up. And so that's why
rockets are pretty inefficient and super expensive. Yeah. So you
mean when you see a rocket, just imagine ninety of
that long tube is basically like an explosive, right, Yeah,

(08:10):
it's not basically an explosive. It is an explosive. I
mean you explode your way to space, right, like this
is this is the plan, right, it is riding explosion
to space. And so that's pretty expensive, right. I was
looking it up. It turns out that if you want
to send one kilogram that's like to something pounds of
stuff into space, it costs like twenty thousand dollars. It

(08:30):
doesn't matter what it is. Gold, mashed potatoes, hamsters, one
ram or whatever cost about twenty thousand dollars to send
a space So it's like ten thousand dollars a pound. Yeah, exactly.
That's some premo caveat you know, um, and say you
want to build something, right, you want to build um
factory in space that can make spaceships, or that can

(08:52):
make habitats or domes or space suits or whatever. Right,
you have to send every piece of that stuff from
Earth because we don't have any manufacturing space yet, right,
and so you have to lift it all. It would
cost so much money, um to make stuff on Earth
and then lift it up into space. Yeah. Yeah, it
would like all those space stations you see and science
ficing movies. You've got to wonder how did they get

(09:14):
all that metal and stuff up there? Yeah, which is
exactly why I think with the future is to build
a space based industry, right, build that stuff in space, right,
building a factory in space to manufacture stuff so you
don't have to lift it from the Earth. But then
first you have to build that first factory, right, you
have to get it started somehow. Well, you have to
get up the raw materials too, right, Well, there's plenty

(09:35):
of raw materials and asteroids. Right, There's lots of good
metals and stuff in asteroids, so you can If you
can build an asteroid mining factory in space, then you're
you're set to go. But the first one you have
to build on Earth and lift it right, Well, so
rockets seem pretty a little bit inefficient and kind of dangerous,
and so there's this this other idea to get things

(09:55):
up into space called the space elevator. Yeah, exactly. And
so we're gonna dig into how a space elevator works
and what should you take one, and is it possible
and is it feasible? But before we do, we thought
we would ask folks around the U C Irvine campus
if they had heard of a space elevator, if they
thought it was reasonable, or if they thought it was
just some crazy idea of fuzzy hair physicist was asking

(10:16):
them about. So before you listen to these answers, think
about it for a second. How much do you know
about space elevators? Here's what people had to say. No,
what would be your best guest or what a space
elevator would be? Um? The one to Charlie and the
chocolate factory? Perfect? M. No, what is your best guess?

(10:38):
If you're a space elevator, can I get? What? Can
I get? A hint elevator to space elevator to space?
And no? Would? I don't think it's that all right,
thanks very much? Any any best guess what that might be?
An idea. Yes, do you think it's possible feasible? It
seems possible. I don't know about feasible. Um, when do

(11:00):
you think we might see one in action? I think
that as I understand it, the limitations have to do
with materials constraints right now and the strength of the materials.
So last I heard they were working on like carbon
fiber that could support its own weight up to the
low Earth orbit. But I don't know how that's going.
Is it like a thing used for like the spaceships

(11:23):
to like launch you that I guess putting a similar
to that an elevator in space, elevator in space or
elevator to space two space? Sure? Space? You'd like to
have a space elevator? No, I think I might die
in it on a space station or something like. It
takes you to the like from the bridge to engineering

(11:45):
or something something like that. All right, maybe something that
launches you into space. All right? So it sounds like
a lot of people ever heard what space elevator is.
Someone said that it was like the one Charlene the
chocolate factory. That was a great answer. I love that. Um.
I love seeing people think on their feet. They're like
I haven't heard that. What could it be? They're like,

(12:07):
I've heard these words before. Space and elevator. Is it
an elevator that uses space, takes you to space, or
an elevator in space? Right? That was one of my
favorite ideas. It's sort of like a star trek when
you go from like the bridge engineering that uses an elevator. Right,
So very few people thought from first principles that it
might be an elevator to space. One of the guys

(12:29):
we interviewed happens to be a professor of Earth system science,
and so he was very knowledgeable about the topic. As
you can hear. Oh, I see, he was a ringer.
He was definitely a ringer. Yeah, he really elevated the
topic here. That's right, that's right before we dive in,
let's take a short break. Right, Le's jumped into a Daniel.

(13:01):
So what is a space elevator? The idea of a
space elevator is to avoid having to do the rocket lift, right,
and instead of having to push yourself up out of
Earth gravity. And every time you're pushing yourself out of
Earth gravity, you're doing two things. First, you're keeping yourself
up and second you're lifting yourself up. So, for example,
say you're like, you know, five feet above the earth

(13:24):
and you just want to hover. You don't want to
go anywhere any higher even that just that takes energy, right,
you have to continually push yourself up. Yeah, so imaginative. Instead,
you could just climb a ladder. Right, there's like a
ladder to space. Then when you wanted to take a break,
you could stop right and you could rest and the
ladder would support you. The ladder would provide that essentially

(13:45):
the counterbalancing force against gravity to keep you up while
you rested, and then did the rest of your climb. Right,
So you can literally just hang out exactly, hang out
in space. Yeah. So if you can build a ladder
to space, then that would save you a lot to
that energy. Right. The other idea is avoid carrying all
your energy with you, right the rocket. As we were

(14:07):
saying earlier, the big problem with the rocket is you
have to carry the fuel and then the fuel to
care the fuel, and the fuel to care the fuel
and all that stuff. Um. And so if you could somehow,
you know, get the energy from the ground as you
were climbing, you know, like people like throwing you, um,
you know, candy bars as you're climbing of the ladder.
Then you wouldn't have to carry all those candy bars
with So the idea of a space elevator is build

(14:30):
something you can climb and send the energy up to
the car that climbs. The climbs the elevator while it's
on the way, so it doesn't even have to carry
it all like the like a real elevator in a building,
like you get the power form it um. You don't
carry all the gasoline to power the elevator. It just
comes to you through the cables attached to the elevator, right,

(14:53):
that's right. This would be a slightly different structure because
an elevator and a building is usually like attached to
the cable and then there's an engine at the top
that pulled on the cable or something. So the basic
idea here is you have a huge cable, you attach
it to the ground on Earth, and then you lift
the other end all the way up into space and
attach it to something in space. So the idea I

(15:13):
said earlier a six year old like lassoing the moon.
That's basically the idea is like tie a string between
the Earth and something in space. Wow, Okay, So I
think the basic basic idea is to build something permanent,
you know, not a rockety used once and then throw
it away, but like build a structure, something like a
link between Earth and space, and then just climb that

(15:36):
every time you want to go into space exactly. Yeah,
And so then it's reusable and you don't have to
carry all the fuel with you. We'll talk in detail
about how you can accomplish that, um and and you
can take breaks, right, you don't have to provide the
hovering lift as well as the climbing lift. So there's
a lot of possible advantages if you can build that
kind of structure. You can just hang on, yeah, exactly,

(15:57):
you can just hang on. You can like clamp on
of the rope or whatever, UM to prevent yourself from falling.
A rocket can't do that, right, has nothing to hang onto.
It's just as the air around it to push against. Um.
And when I first heard about the concept of a
space elevator, I thought, like, how is the rope going
to stay up? Right? I mean, if you just if
you take a long rope and just like throw the
end into the sky, it falls down, right, There's no wait,

(16:20):
like stays up in the sky. How does that even work? Right? Well,
you're assuming that it looks like a rope, right, Like
a like this elevator could take different forms, Like it
could be just one rope that goes off into infinity
like Jack and the bean stock, or it could be
what if you just build a really really tall tower,
like if you just you know, the berke Khalifa and

(16:42):
and um Dubai. What if you just keep building that
up up up into space. What would happen then, Well,
the bottom of the tower, wh we get crushed? Right?
The problem with building something up from the ground and
not having it be pulled from outer space. So that's
the key about the space elevators, that you build it
so so long and so high lions and the rope
goes so far that it's basically getting pulled from space.

(17:04):
We'll talk about that in a moment. But the problem
with building a tower, it's basically like a compression structure.
Every layer sits on top of the previous layer, and
then the next layer sits on top of that, and
by the time you get to you know, really really tall,
the bottom layer is supporting the entire structure. Right, And um,
that has to be super strong or super wide or
made out of crazy materials to go anywhere close to

(17:27):
the distance of space. So you have to have this
thing be really light so we can get height without
having a lot of weight. But technically it's possible, is it.
Is it possible to just build a giant pyramid that's
really really tall? Is it possible? I mean, the Mount
Everest is a giant pyramid that's pretty pretty tall, But
I don't know if we could build it, you know,
like it's, uh, these things have to go get pretty

(17:49):
wide in order to support all that weight. Um. Eventually, yeah,
maybe you could build the tower and babble into space.
But I think it's as as difficult as space elevators are.
A space tower be even more difficult. I see, all right, Yeah,
the space elevator has the advantage that the top of it,
the rope, is so far out into space that it um,

(18:09):
it pulls on the rope. Okay, yeah, I just think
maybe we're jumping ahead, right because maybe some people think
it's an elevator, so it just it means that there's
an elevator shaft that takes you all the way up.
You're saying that the primary way that this might work
is using a cable. Yes, yeah, exactly. It has to
be a cable. You can't just build a building that
goes all the way up into space. That has to
have something at the top of it that's so far

(18:31):
into space that it's basically escaped the Earth's gravity and
it's pulling, pulling whatever it is up and so that's
that's is that the prevailing idea that this this way
it could work. Maybe, like the idea is that it
it's it's not an elevator shaft or a tower. It's
a it's like a string. Basically, you attach a string
to Earth and you swing around something really heavy out

(18:53):
into space that keeps the that rope that's string intention
yeah exactly, and then maybe you can use that thing.
Maybe you can climb tim that rope in tension that
rope up into space. Yeah exactly. You attach a string
from the ground to something up in space, and that
thing up in space is pulling on the string, right,
it's keeping it up um and then yeah, and then

(19:13):
you just climb up that rope. And so it's more
like a space ladder than a space elevator. If if
you want to think about it that way, Yeah, like
a space space cable, like a space fire pole. Right. Yeah,
but then you would ride an elevator like you would
be you would wait, you wouldn't climb it by hand.
You would be inside of an elevator like structure that

(19:36):
then climbs up the rope or the pole. Yeah, you'd
have to be crazy strong to climb in by hand. Yeah.
The basic components are you have stationed on the ground,
the cable that goes up, some counterweight up in space
to keep it up, and then you have something that
climbs it, some like car or some device that basically
crawls up the rope, the thing that climbs the ladder

(19:57):
for you, and that slips its way up the rope.
So those are the basic components. Yeah, it's hard to
imagine how that rope stays up, Like what keeps that
rope vertical? Yeah, exactly. That's the thing that puzzled me
for a long time when I was thinking about the
space elevator, because it's just counter to your intuition, right,
you think the things that go up in the sky

(20:18):
come down, right, But the truth is, if you throw
things high enough up into the sky, they don't come down, right,
they go into orbit, and so at some point the
force of gravity weakens enough and the centrifugal force is
strong enough that they stay up there. You know, imagine,
for example, you are you have a bucket with a

(20:38):
rope and you're swinging it around yourself. Right. Then you know, water,
for example, can stay in the bucket even if the
bucket goes upside down. Right. Is that it's because of
this apparent force, the centrifugal force, and so that's pushing
things away if you're spinning, right, the fact that the
Earth is spinning provides this sort of outwards apparent centrivigal force.

(21:00):
And so it would be like the Earth is rotating
around and you tie string to it, and the swinging
around of some big weight at the end of the
rope is what keeps the rope vertical and intention and
then and then you can climb that rope to get
to space. Exactly, the center of mass of the whole
structure is above the orbit level. Right at some point
above the Earth, the force of gravity gets weaker and

(21:22):
the centrifugal force actually gets stronger with distance, and so
at some point above the Earth they're equal. That's what
we call like where a geosynchronous orbit can happen um
where it's in balance, it can just stay in orbit.
And so the idea is to put something really heavy
above that so that the average weight, like where's the
average bit of mass of the space elevator is above

(21:42):
that orbit level and so it's just like something in orbit.
I mean, you can think of it like something in
orbit with that with that dangles down really really low. Oh.
I see, it doesn't have to be attached to Earth,
is what you're saying. It doesn't have to be attached
to Earth, but it's better if it is, right, you
don't want to climb someone which is actually angling. But
just in the point of view of the physics, like
why does it stay up? It's uh, you know, the

(22:04):
fact that it's attached to Earth is not what keeps
it up, right, the thing that keeps it up, that's
what he said. It's attached to the part in space. Right.
That's interesting, Like people in the International Space Station could potentially,
i mean physically just kind of let out a little
bit of string down into Earth and at some point
it might touch the Earth and it would just hang
there between the station and Earth, right, And your intuition

(22:26):
tells you that should work, right, and that's basically the
same thing. Yeah, and then you just clip that rope
tier a garage and you're done. Yeah. But the key
is that the thing is in geosynchronous orbit, right, so
it's always above the same part of the Earth. Because
you don't want this robe like dragging across the surface
of the Earth, right, that wouldn't be a lot of fun,

(22:48):
like Bruce Willis movie, exactly exactly. So you want to
have some like big station on the ground where this
thing clips in. And so you have this like a
spaceport on the ground and then a place you can
arrive I have above the Earth. And so that's the
basic physics of it. Well, this is pretty cool, you said, um,
you you told me that basically the point at which
you would reach this geo stationary or orbit is about

(23:10):
thirty six thousand kilometers out into space. Yeah, exactly. So
you need to have enough mass above that height so
that on average, the mass of the whole thing is
just above thirty six thousand kilometers above the Earth. And
just for reference, like the Moon is about three eight
thousand kilometers way, so it's like a tenth of the

(23:32):
way to the moon, you could have this elevator, yeah exactly.
So that makes it sound totally plausible. Right, you don't
even need the last of the moon. You just have
to last of the space station, right exactly. But that's
a really long rope. Right, Well, let's see how long
would it take you to get there, liked my kilometers away,
and let's say that your elevator is going up at
a two kilometers per hour, it would take you hold

(23:55):
on how much of that? Well, that's you know, five
hours to go a thousand kilometers, right, so hours or so,
So that's a few days. You know, when you get
in at the bottom, you're gonna look around because you're
gonna be with those folks for a while, and then
I hope nobody um passes some wind or exactly. Bring

(24:18):
pay attention to what everybody's eating just before they get
on the space elevator. You know, it's a lot like
a super long airline flight, but days long, right, Wow,
that'd be amazing. But then at the end of the
two days, at the end of the what is it,
ten days, you'd be in space. Yeah exactly, you'd be
in space. And even that number, like two per hour.
That's pretty fast. That's pretty fast for an elevator, right,

(24:41):
So I don't know how plausible or how comfortable that
would be. Um, it seems to be pretty sippy for
an elevator. But if you get those speeds up, then
you can get the time down. Um. And you know,
ten days is a long time for a passenger. But
I think in the beginning, the more important thing is
lifting up cargo. Right. If you're gonna build industry in
space so you can build spaceships and how the tats
and all that kind of stuff, then you're gonna you're

(25:02):
gonna lift stuff up into space. Okay, so that's the concept.
As you do, you put a cable between the Earth,
you can tie it down here, and you tie the
other end to something heavy and swinging around the Earth
in orbit geosynchronous orbit, and then you just pulled yourself
up to cable to get to space. Sounds simple, just
put yourself Yeah, let's do it. Well, I'm gonna I'm

(25:22):
gonna take care of this. I can imagine you selling
tickets at the bottom. You're like, it's a thousand dollars
and just you know, pull yourself on up. Yeah. Well,
let's get into why it's possible or maybe impossible. But
first let's take a quick break. All right, So that's

(25:48):
a space elevator. It's a giant rope tied to Earth
and tied to on the other end to something floating
out into space. And the idea is that we just
get on an elevator elevator that climbs that rope. So
so where's the what's the difficult part here? Why can't
we just build one? Oh? I'm building one right now,
should be done next week. You want to come down China.
It's made out of paper clips. I can see it

(26:08):
from here. Oh my gosh. Um, there's a lot of
hard parts in this. First of all, you're talking about
attaching a rope to something heavy out in space. What right,
Like do you corral and asteroid? Do you collect a
bunch of space junk and build a garbage mountain in space?
Like you need something big and heavy that you can

(26:29):
understand and snap a cable too? And wait, wait, why
does it need to be? Like? How heavy does it
need to be? Like does need to be uh, you know,
like a the size of the moon or the size
of a bus or or what it needs to be
definitely thousands and thousands of kilos. Exact size depends on
the distance. So the longer your rope, the further away
this rock can be, and the lighter it can be.

(26:51):
Right because this centrifugal force grows with radius, and so
it doesn't need to be as heavy if as longer,
but then you have to build a longer rope. If
you want a shorter rope, then you need a larger
mass um and so it's a bit of a balancing act.
We just collect all those junk satellites and make a
giant satellite ball and that's it. Yeah, yeah, Or maybe
we could just like gather all the plastic from the

(27:11):
ocean and use that, right, a huge um you know,
plastic straw ball in space would be pretty cool. So
that's problem number one. Yeah, that is the thing that's
out there holding the elevator up. Yeah, but the bigger
problem is connecting it right, Like, say you have a
big asteroid in space. You're all set to bigger builter
space elevator. How do you make such a rope? You know,

(27:32):
this thing has to be like thousands of kilometers long,
it has to be super strong, it has to never
ever ever break right, And most importantly, it has to
be strong enough to hold itself up. What do you
mean strong enough to hold itself up? Didn't we say
that the rope is pretty much kind of floating out
into space. Yeah, well you can imagine this sort of

(27:53):
two halves of it. Right, there's some average point where
half the mass of the space elevators above it and
half the masses below it. Everything above that point is
getting pulled out into space. Cool everything below that point
is getting pulled down towards the Earth. It still has weight, right,
So even if the whole thing is being held up,
then the those elements of the rope that are right

(28:13):
there at that halfway point, they have to be strong
enough to hold all that weight below them, even if
there's a force on the other end pulling on the
rope to provide it to keep it up. The rope
has to be strong enough, right. But why does it
need to be intention, I guess is my question, Because
couldn't you just have something in geosynchronous orbit, Like something's
in orbit, it's not there's nothing holding it, right, So

(28:34):
couldn't you just have a slack line. Well, I think
a slack line would make for a pretty wild ride,
you know, are not a completely taught or like a
barely taught. It's not about the tension, right, It's just
about having having a really really long cable that's suspended
by itself. Right. Even if you lower say you lowered

(28:54):
that cable from the space station, right and you didn't
even tie it to Earth, the part where it attaches
to the space vision is going to be pulled down
by the entire weight of the cable. Right. The cable
itself just has to be strong enough to hold that weight.
It's not about the strength of the pulling force. Like
let's say Superman wants to pull on the Moon. Okay,

(29:15):
so yeah, maybe he's strong enough. He ties a rope
around the Moon, and he's strong enough to pull hard
enough on the rope to move the to move the Moon.
But is the rope strong enough. Probably not, Probably the
rope would snap, right. So this is about making a
rope that's strong enough to hold all that weight, hold
all that that force that's keeping it in space. Oh
I see, So that there doesn't need to be tension

(29:38):
between the space object and the Earth. But the rope
it self weighs a certain amount exactly, so it's um
it's being pulled down by itself basically, Yeah, exactly, it's
gonna be strong enough to hold itself up, So you
need something which is really strong. He also wanted to
be very light so that it doesn't have to be
that strong. So it's this constant balance and people and
materials are doing this kind of research all the time

(29:59):
trying to make really strong, really light materials, not just
for space elevators, you know, for like bulletproof vests and
for buildings and for airplanes, and like, being both strong
and light is like one of the hardest things in materials, right,
you know that you're an engineer. Yeah, I thought we
was gonna say. I thought you were going to say
that I am strong and light, which is totally true.

(30:19):
Thank you, Daniel. You're brilliant like light, and you're also
very strong willed. So there you go of a strong
personalities what you're saying exactly, And so it's difficult to
find materials that are strong enough to fit the bill.
I mean, this thing is crazy long, right, It's like,
I mean, thirty six thousand kilometers is uh is It's

(30:43):
just a huge number, right, And so we've never met
anything that long. We don't have materials that can hold
themselves up when they're that long. That that would be
like a rope that goes around the earth basically, right,
like you you start a rope here and you keep
going until you come from back on the other end,
from the other side. That would be how long the
rope would need to be, right exactly. It's it's crazy.

(31:03):
It's hard to even really imagine building something that big,
literally planet sized. Wow. Okay, so um, and so what
are the alternatives like titanium, What if you use titanium
or at a mantium at amantium, you know, if you
use marvel comixium, you know then and you can do anything.
You know, the strongest metals we have, if you made

(31:24):
a thin rope of them, they can hold themselves up
if you make it like you know, twenty or even
thirty kilometers long. But eventually, um, eventually they just fall apart.
Right the weight at the bottom will be stronger than
the than the internal strength of the material. It'll tear
itself apart. And you can try lighter stuff like kevlar,
carbon fiber. These are fancy materials people developed. They are

(31:46):
pretty light, and those can maybe make like, you know,
a hundred kilometers, a few hundred kilometers, but remember we're
looking for something that's like tens of thousands of kilometers.
And so recently people have in research and they've come
up with even crazier materials, Like have you ever heard
of carbon nanotubes? I have? Yeah? Is that like um? YouTube?

(32:09):
Is that like um? Like bread? Is that the Yeah,
it's the the super premium version of YouTube. Exactly. The
carbon nanotubes are this really cool development. It's a totally
different way to arrange carbon. Carbon is an amazing element.
You know, it's the backbone of organic chemistry, right, every
molecule in your body has carbon as its backbone. It's

(32:31):
incredibly flexible. Also, it doesn't have a lot of protons
in it because it's early in the periodic table, so
you can make structures in it that don't have a
lot of like dead weight. Like a lot of the
materials we use, the protons and the neutrons, which provide
most of the weight of the stuff, don't really contribute
much to the strength of the object. But a carbon
nanotube is like pure chemical bonds, right, yeah, exactly. Most

(32:55):
of the strength comes from the chemical bonds, which really
just come from the electrons, which are pretty light. So
you want to find a material real which has a
small number of protons and neutrons like carbon and can
arrange itself in clever ways. And so people have figured
out ways to make like these spherical shells of carbon.
Those are called buckeye balls, or these tubes of carbon.
It's really pretty incredible, and of course folks out there
might know, like carbon can make graphline, it can make diamond, right.

(33:17):
It's really it's like a you know, an engineer's dream
when it comes to a basic building material. So this
is almost kind of like a cable made out of diamonds, right,
almost like it's it's a very specific carbon arrangement. Yeah,
it's exactly. It's a very specific arrangement of carbon, and
people have and they're incredibly strong, right, They're stronger than

(33:37):
anything anybody has ever made. And the current calculations tell
us that, like you could probably make a carbon nanotube
that goes five maybe ten thousand kilometers and you could
hold itself up um, which is pretty good. Right, that's
getting in the range of what you need is still
a little low um. But the problem is that we're

(33:58):
not really that good making carbon in the tubes yet,
Like the longest one we've ever made is like centimeters
in length. Oh, so we're almost there. Well, I've heard
this idea of using carbon nanotubes, which I know they
are like single atom, single molecules strands, and I was thought,

(34:20):
what You're gonna pull a whole elevator on a single
strand of molecules. But I think the idea is not
that there's a single strand up to space, but like
a like a bundle of these fibers, right, yeah, I
think you can weave them together to get additional strength
and also redundancy. Right. Another problem with carbon nanotubes is
that they're not very robust too. For example, lightning strikes, right,

(34:43):
you strike it with lightning and basically evaporates. So that
means that means you need to like always predict the
weather exactly correctly or you're susceptible to these lightning strikes
to you know, evaporate your your cable. That would be
a long ride down if your space celebrator gets fried
by lightning strike. I think it's faster on the way

(35:05):
down there on the way up. If you if the
cable snaps. Um. Yes, there's a lot of challenges there.
We don't even have do We don't have the technology right.
Carbon nanotubes aren't yet good enough, and we don't even
know how to make carbon nano tubes that are long enough.
But I mean physically carbon tubes could be could work
or did they just even those are not physically able

(35:27):
to get to thirty six kilometers. I think there's a
lot of uncertainty still because a lot of ways you
can make them, and so people think about weaving them
together and to get them extra strong. So I think
it's possible. Right nobody knows exactly how to do it,
but I certainly wouldn't say it's ruled out. Um, it's
definitely in the category of things that the people imagine.
You just have to find a right solution, like the

(35:48):
right engineering material solution. And one of the problems is
that often you're surfing on the backs of other industries.
Like there if there are other reasons why people are
trying to push to make long carbon antitubes, then cool
Space Elevator can wait until some other industry figures out
the problem and then they can just order a big tube. Right.
Problem is nobody else really needs carbon nantitubes thousands of

(36:11):
miles long. Right, We need them for electroc electrical conductivity,
and all sorts of other applications that are you know,
millimeters or centimeters or spider Man. Spider Man needs them.
He makes them himself though, and he's not shared the patent,
so we're screwed from that point of view. Um, So
you need a dedicated effort to develop these things to
be long enough for space elevators. And that's expensive, right,

(36:33):
That's a huge investment, And so you're saying it's like
a nascent industry like, um, there's a lot of applications
of them, um in in solid state physics, you know,
and and in biophysics and using them for all sorts
of stuff, But most of those applications they can be
pretty short, right, he used They use them for connectivity,
for circuits, for like filtering stuff, for picking stuff out

(36:54):
of other kinds of Google. But nobody really else, nobody
else other than space elevators needs them to be this long.
So you need somebody to develop it. But you know
there are people out there who are working on it,
people who think this would be awesome, or people who
correctly think it would be huge economic windfall the first
person to build a space elevator, you know, and instead
of charging dollars per kilo, could charge like their very

(37:15):
reasonable price of five hundred dollars per kilo. We'll get
a lot of business. Wow. But you're saying, um, this
might be achievable with a few if we just invest
enough money in it into it. Yeah, it might be right.
Somebody needs to develop the technology to build these long
cables and to make them robust um. And you know,
people estimate how much this might cost. It's really just

(37:36):
speculation because nobody really knows. It's research. Right. You could
have a moment of inspiration and figure something out tomorrow,
or you could sink billions of dollars in and get nowhere.
But it's definitely in the billions or tens of billions
of dollars category in terms of research projects. Just people saying, hey,
if you can give me twenty billion dollars, I'll get
you into space. Yeah. I wouldn't believe a firm price tag,

(37:56):
but that's probably the right order of magnitude is you know,
ten or twenty billion to develop and to build this thing.
And you know, some people are talking about like trying
it first on the Moon, because on the Moon to
be much easier because the gravity is much lighter on
the Moon. So the space elevator wouldn't need to be
as high, wouldn't need to be as long, it's not
as risky. You mean, like a space elevator from the
Moon out into space to take off from the Moon, Yes, exactly,

(38:20):
out into orbit around the Moon basically just as a
sort of a warm up project. Because also, imagine you
build a space elevator and it's working fine and then
it breaks, right, that could be a big disaster. Like
what if it breaks um where the cable snaps um
at the top end? Right, Then this huge cable falls

(38:41):
from the sky right, and it's as you said, it's
as long as the circumference of the Earth. So like,
where is this thing in a fall? It's gonna slice
people in half? Like it seems crazy, it would keep
falling for a long time. Yeah. Or if it snaps
at the bottom right, and then you're dragging this like
very sharp, hot, fast moving cable across the surface of

(39:02):
the Earth, right, Wow, none of these pictures sound very rosy, no, exactly.
And so if you're considering investing in the Space Elevator company.
Think about the lead of liabilities right well, which is
why I think we should just make it out of
um spider webbing, which is um the spider Man answer
your phone calls? These days? How do you tell how

(39:24):
much is a Marble movie? Abo million dollars done? You know?
One of my favorite science fiction stories is about a
physicist who has an idea for some awesome technology and
he can't get any funding agencies to fund it for him,
so instead he pitches it to Hollywood as a movie
and then make a movie, and he uses Hollywood's huge

(39:46):
budget to build the quote unquote prop of his device
and it actually works, and so he uses Hollywood as
a as a way to fund his research. Should you
should pitch it as a movie? A movie about a
guy who talks on the podcast about a story about
a physicist. It sounds like an awesome pitch so far.

(40:07):
I can just imagine you're going to like a movie
studio head of meaning, Kay, sir, can I give you
my quick elevator pitch? That's right, we have we're taking
the space elevator, so I have ten days to give
you my pitch for this movie. Okay, great, So so

(40:27):
that's the that's the the space elevator. It's it's um.
It would sort of liberate us from this need for
rocket fuels and rockets and which are explosive and expensive.
That's right. And we didn't even get to touch on it,
but very briefly, like you could avoid having to carry
all the energy for the space elevator by like using
laser beams. You could like shoot laser beams from the

(40:48):
ground to send energy out there, or to use carbon nanotubes.
You could they could be electrified, so they could like
send the electricity along the wire like a like an
electric bus or something. Stop stop right there and just
call it a laser space elevator. I mean that just
sells laservator, laser space evator. How are you gonna get

(41:10):
to space? I'm gonna laservate mis way to space? Cool?
Good luck with that. Where a helmet? Um? Yeah, But
I think this stuff is important. I think it's interesting.
I think if we're going to build a space industry,
if we're gonna develop humanity into space and and you know,
populate space and and all that kind of stuff, we
gotta get started. We gotta get over this hump where
it costs so much money to get something into space

(41:33):
and it's so risk and it takes months of planning. Right,
it has to be more routine, has to be cheaper. Yeah, yeah,
avengers get on it. So or half to listen to
all of that. If somebody builds the space elevator, would
you pay to take a ride up into space? Let's
do the calculation. Save costs two hundred dollars per kilo?
Right then? How much? How much would your ride on

(41:54):
the space elevator cost? How much would it for me? Really?
Like that sounds like ten bucks or something? All right,
So would you spend ten thousand bucks to get into space? Totally? Yeah?
Wouldn't you? I mean if it was viny was safe. Yeah, well,
I'll take your deposit right now. What was your credit
card number? No, I probably would. I think getting to

(42:16):
be up in space would be would be exhilarating. Um
of course, have the price drops that low, then you
know a lot of people will do it. Maybe won't
feel as exciting anymore. I think it would also depend
on who's going on an elevator with me. When you're
on a transatlantic flight, do you like stare out the
window agog at the technology anymore. No, you're probably just
like watching movies. You lower the window, you ignore what's
going on outside. Right, People adapt pretty quickly to this

(42:38):
kind of stuff, like a real elevator. Right, Like if
you showed a real elevator to someone ten years ago,
to be like what, you can go up? You can
go up a thousand feet up intil into the air,
just by getting onto this box. Yeah, in these days,
people just like impatiently mashing the buttons, cursing the thing
for being so slow. Right, humans never satisfy. Somebody told

(43:00):
me that New York is the only place where the
closed door button actually works. What are you saying the
closed door button doesn't usually work. I think that he's
there for a psychological Oh my god, that blows my mind.
Are you serious? Yeah? You have you ever been in
one where that actually works? I don't know. I guess
I had the impression that frantically mashing that button did something. Yeah. No,

(43:24):
I'm gonna apply that. I'm gonna apply that technique to
other places, you know, like, Um, I'm having a knob
a button outside my office door that says complain to professor,
and people come over and just mash the button and
feel satisfied. Ring ring doorbell for physics answers, And it
doesn't do anything, And it doesn't do it just pulls

(43:44):
up a copy of our book. We have no idea.
So there you go. There you go. Well, I hope
the next time you get into an elevator, um you
maybe imagine yourself getting onto the space elevator and imagine
and when you get off that you'd be in a
whole different world. Or I imagine that maybe one of

(44:04):
our listeners has heard about space elevators for the first
time it is so inspired that he or she will
sink their fortune into investing in space elevators and make
it real and actually go to space. So it's John
let the carpet said, engage. All right. Thanks for listening, everybody,
and if you have questions about what we said, send
us some feedback at Questions at Daniel and Jorge dot com,

(44:28):
or send us a suggestion for what topic you'd like
to hear us talk about. Thanks for listening. If you
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You can find us at Facebook Twitter and Instagram at

(44:50):
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