Shkadov Thrusters: Moving the Solar System

that he's out discovering the amazing technology of tomorrow. But really what he's probably doing is posing for selfies with very muscular men. Yes, that is entirely likely. You can watch the House Stuff Works dot Com channel on YouTube to find out more about that in a few weeks. Yeah, so today we wanted to address a listener request episode. Our listener, Keith on Facebook, has asked us to talk about all kinds of topics and we can't do them all at once, so we decided to pick the coolest,

weirdest one of the bunch, being Stellar Engines. Stellar Engines. Now I know what the gearheads and the audience are thinking. Cadillac V eight right, the classic Cadillac V eight Stellar out of this world? Right? Yeah? Oh man, they don't make them like that anymore, or I don't know, they might still make those spoiler alert, I don't know anything about cars, um, But no, the use of the word stellar here actually refers to the more classical sense, as

in stars. Yes, stars turned into engines. Put to our own devious uses, what would a star based engine even be? Um? As it turns out, it's real complicated, y'all, And it's really weird and really really cool. This is one of the coolest ideas I think we've looked at in a while. And it's also kind of cool because it's not even close to reality. So this is going to be one

of our more on the speculative end. So yeah, this is not one of those like twenty to forty year kind of things that we usually wind up talking about on the show. This is so far out there thousand years in the optimistic sense. So, okay, let us talk about interstellar travel. Sure, well, we all know that one day we may want or even need to travel to another solar system. And what's wrong with our solar system? Joe? Well,

you know, it's just in our Solar system. You get board being in the same place for a long time. I know, after a while, just seeing the same planets going around and around over and over. Don't you ever get tired of Mars? Yeah? Yeah, you get that interstellar wonder lust. Well, it's not just boredom and uh and discontent that might make us want to look to another solar system in our galaxy solar on we over time, our son is going to get into some trouble. Have

you heard about this? H Well, I mean it's pretty much a bad seed. Yeah. Well, okay, so today we have our our healthy yellow son, the one that makes Superman as powerful as he is. Not all sons are like this, and in fact, sons have a lifetime, just like living organisms do. They sort of increase and decrease in luminosity at different periods of their life, and eventually they use up all of their stellar stuff. Right, the fuel that they that they fuse, the hydrogen that they're

fusing to be that healthy yellow star. You know, it's not infinite, so this can be bad for planets orbiting the star. In October, there was a NASA blog post that was explaining that a team of astronomers had recently discovered evidence through a ground based telescope that there was this red giant star called beat plus forty eight seven forty and it was swelling to completely engulf a planet formerly in its or it So how did they figure

this out? I thought this was really interesting. They realized the star had quote the fumes of a scorched planet

in its atmosphere unquote, So the star aida planet. And we figured it out by smelling the star's breath, uh telescopically nonetheless, right, So yeah, they smelled its breath with spectroscopic analysis, so that you know, looked at the colors, uh, the luminosity coming off of the Sun, and they can look at what materials are in that based on that data, and they found that the star contained lots of the

element lithium. Oh yeah, that's not something that you usually find in a red giant, right that That would be a very weird thing to find a bunch of in a in a star like that, because typically lithium gets destroyed inside stars over a long period of time, and red giants tend to be old. But you might find lithium in a star if it's if it's being produced by the consumption of another big chunk of matter, and

that's what they figured out happened. There had been another planet there that probably spiraled into this red giant as it heated and swoll on up, and it was like oh no, no, no no, and it ate the planet. It it quote ingested the planet. Okay, so this is eventually going to happen to our son and our planet. And I'm not talking about like in the next twenty to forty years that this is. This is a few

billion years down the line, yes, right. One of the researchers who found the evidence of this said that the same kind of fate could be in line for the inner planets of our Solar system within about five billion years. Now five billion years. It's it's hard to get two worked up about five billion years. Personally, I worry a lot, but yeah, I'm not. I can't actually be worried about that.

But at least we we may worry for you know, our descendants or the or our you know, the robots built by our descendants that take over the planet, or the distant future progeny of zebras. I care about future zebras, Zebra babies of the future, right, right, well, unfortunately for the zebra babies, they won't be able to wait for the Sun to all out eat the Earth started. That

bad stuff will happen way before that actual consumption, right. So, yeah, as the intensity of solar radiation bombarding the Earth slowly gets stronger, and it just will steadily over time, Earth will at some point become unable to sustain life. So in there was a three dimensional climate model devised by the and I apologize to French speakers out there, but I'm going to try to say it the Laboratoire day

meteorology dynamic. Dynamic, Yeah, I don't. Yeah. So this climate model that they came up with predicted that the solar radiation will increase the Earth's surface temperature enough to boil the oceans and cause Earth to lose all its liquid water in about one billion years. That is a much tighter deadline of Sun eating us. Okay, so before then, I gotta find a plan. B We we can't just

wait it out. So a pretty straightforward one would be to move to move to a nicer neighborhood, find a new planet in another solar system, and get all of the humans there or all of the zebra people of the future grandchildren. But moving all of these organisms to a new planet might not be so easy. So we've talked about the problems with interstellar travel unless you've got a spaceship that goes the speed of light or faster,

and we all know the problems with that. You know, Einstein's special relativity says you can't go faster than the speed of light. We may someday come up with some crazy way to bind that rule, but we shouldn't bank on it right now. It seems kind of like a law of physics. So unless you can get pretty near the speed of light, the journey between stars becomes prohibitively long, like probably thousands of years. Uh. The nearest star to Earth is the tiny red dwarf star Proximus Centauri, which

is in the Alpha Centauri system. It's about four point two light years or about thirty nine point nine trillion

kilometers away. At the speed Voyager left the Solar System, which is around thirty seven thousand miles per hour, I see slight variations on that would be about you know, almost sixty thousand kilometers per hour, which is the quickest that anything that has survived its a journey thus far has ever moved, right, Yeah, and so at that rate it would take Yeah, it would take about eighty thousand years to reach Proximus Centauri. Uh, that's I mean, I guess if you're talking in the scheme of of a

billion years, that's not so long. But tightening that up would be preferable, especially if that's just the journey to a kind of crappy star up, if we're being really honest, Yeah, it's this little red dwarf. I mean, you've got to you can't just go to any star with the spaceship. You need to find a planet to sustain life, right, and not all planets are suitable for habitation. In fact, most probably aren't. It could be too hot, too cold,

just in a constant bath of radiation. There might be a gas giant that's full of radiation itself, and of course you can't walk around on it. A good Earth is really hard to find. There's the other problem of once you're on the way, how do you keep yourself alive? How do you keep supplying yourself with food, energy, air, protection from radiation? In interstellar space, you could work on building sort of generation sustaining starships with ways of continuously

creating new energy, maintaining an earthlike environment, etcetera. But then you're almost talking about having to build a second Earth to travel with you, and we're already on this perfectly good Earth. If the problem is the Sun, why not find a new son, Why not find a new Sun. So the idea here becomes that we could take everything we have with us when we travel to a new new solar system, literally every single thing we have, including the Earth, and for the journey at least including the Sun,

because we are using it as an engine. An engine. You say, and engine, and I say, actually, I didn't say it at all. Well, no, this idea comes from others who have come before us. Who I mean, Yeah, I literally just said it out loud. But it wasn't my idea. Who were physicists who had incredibly strange and very cool ideas. So where does this idea of a

stellar engine come from? Well, the original paper we want to look at is something from October of nine, and it was when the Russian physicist Leonage Skodov proposed a really interesting idea atty Congress of the International Astronomical Federation meeting in Brighton in the UK. And he said, what if you could turn an entire solar system into a vehicle or in his own words, quote a thruster for solar system motion control? How on Earth would that work?

Or how on the galactic plane would that work? Yeah, we don't even have words for this context. It's really strange. So to clarify, the solar system is not motionless now, oh no, of course not. It's moving all over the place. We're not all over the place. I mean, there's there's a system of movement which it follows. Yeah. Well, just like the planets in our solar system or in orbit around the Sun. Our solar system is in orbit around the center of gravity of the Milky Way Galaxy, and

of course the Milky Way Galaxy self is moving. But we're talking about controlling the trajectory of motion within the galaxy. So what did he have in mind. Here's the basic setup that Shadow envisioned. So you create a spherical arc mirror, basically a giant curved mirror that's a concave one facing

our Sun on the inside. So imagine sort of a giant contact lens with the inside of it the curved inner side being a reflective mirror surface and that's pointed toward the star, in this case, our sun, like like like putting a like putting a big bowl of a few feet away from a grape. Yeah, yeah, sure. So this mirror would have a couple of forces acting on it.

If you have gravity pulling it towards the sun, the Sun's gravity pulling it towards the Sun, right, and since it would be a very large structure, it would also have some gravitational force of its own. Uh. Then it would also have radiation pressure pushing it away like a solar sale. We've talked about solar sales before. Yeah. Yeah, because the radiation, the electromagnetic radiation from the Sun does

have a pushing force. Yeah, we don't really feel it normally because it's a very relatively tiny force, but on a huge reflective surface in space, it makes a difference. The sunlight pushes, so the mirror would become settled in a place where these forces equalize, the solar radiation pushing

the mirror out and the gravity pulling it in. But solar radiation would reflect off of the mirror instead of radiating out into space like it normally does, and it reflects back in the direction it came from towards the Sun. Shadow's idea was that you could use this system to control or at least help direct the motion of the Sun and with the Sun, the rest of the Solar system. Now, Lauren and I spent a lot of time staring at some math we toe really didn't understand ch time. We're

not We're not astrophysicists, y'all. Yeah, let to see if we could say a little bit more about the way this thrust is generated. But if it is not abundantly clear, we are not astrophysicists. And suffice to say, the experts know what they're talking about. You could, in theory, use one of these things they say to perturb the motion of a star within the galaxy. Yes, and that is the official terminology that I've seen people use, perturb, which I think is just a really great verb to to

apply to the Sun. Like you're annoying. I could perturb the Sun, turb the heck out of that Sun. Well, the Sun started it, I mean, we didn't tell it to swell into a red giant and eat the Earth, all right, So so so so we've got these this this dish and this this mirror and all of this is creating thrust in a direction to move the Sun,

to move the Sun in the Solar system with it. Right, So we would call this a class a stellar engine or a scatterw thruster, and it would be sort of like a giant steering wheel for the Solar System, driving it where in the galaxy we wanted to go, and the movement would be really slow. We need to stipulate that, Yeah, very very slow. The obvious advantage though, would be that we wouldn't have to leave the Earth our home, or the Sun our energy source until we arrived at our

destination in another Solar system. And then the final idea of this, the sort of ultimate conclusion, is that we could plan the movement of our Scotov thruster just so that Earth could be deposited into a circular orbit around another star. Yeah, once you get the Solar system close enough to a new solar system, you just kind of let it get nudged in, right, You line it up just so that the Earth gets captured by the gravity of the new star. And then we're back in business

and we can keep making new Zebra children cities. Yeah, Zebra robot children cities. Indeed, now I know this sounds super sci fi, and to be honest, it really is. I mean, we don't have the capability of building anything like this right now, but it is an idea worth taking seriously, even just for the very long view of the survival of our species or maybe you know, our

our our terrestrial organic form, whatever that might be. There is a great article that we were looking at in Popular Mechanics from July of last year that actually examines how you would build a scatter of thruster. That was really helpful. Yeah, yeah, because there's so much that you have to take into consideration here, um, like like where do we get the material for creating a mirror of this size and capacity? Right? Because exactly how big is

the mirror we're talking about here? Um? Yeah, you know, just hundreds of millions of miles across. It would have to be in in diameter greater than the distance from the Earth to the Sun. Um, and it would which would probably mean that would have to weigh some sextillion or septillion, like even up to septillion pounds. And if you need a concept of what that's like, I'm crossing concepts a little bit here, but that's that's roughly the mass uh of like Pluto or the Moon, or Mercury

or Mars. It's a little bit, it's a little bit. It weighs a little bit less than Earth itself. So so we we don't really have like a factory that could build this. We do not have a spare Earth to to to to create this mirror out of. But hey, we do have those other planets just mentioned. Oh no, are you talking about dismantling a planet and making a megastructure out of it? I'm not talking about that, but

scientists certainly are. Yeah. Yeah, you'd you'd have to build it out of something um kind of light and and foil like relatively on the on the scale of metals, something like chematite would be really good for that. That's sort of like an iron ore. Yeah. Yeah, and you could mind something like that out of the planet Mercury. And so if you basically disassembled Mercury and and I can still not hear that word without just thinking, let

no disassemble, Stephanie um. But but yeah, if you took apart Mercury and used the entire planet to build this, this sale this mirror, then you could make it work. Wow, I mean that is crazy, But then again, we are we are talking about sort of a a multi generational project that would have to be pretty far in the future. Yeah, and we would miss mercury. I'm sure it would mess up astrology a whole lot. I know, right, but wait a minute, no, no, no, no more mercury and retrograde.

That's a bad thing, right, the thing people don't like. You know, it's terrible. It's like I lost my keys mercury did it something to that extent. Yeah, and and so so it sounds crazy, but um, it's actually a lot less crazy than trying to catch a lot of asteroids or something like that to do the same job. And and of course, by when I said that you would be disassembling mercury, I did not mean Joe, and I didn't mean that the Royal you. This would probably

be a job for robots. Yeah. Yeah, I would have to be some kind of a massive fleet of robots doing this autonomously. I mean, it just really wouldn't make sense to go try to put people on mercury to mind its surface. Uh No, that would go poorly for people.

So we're talking now essentially about mining mercury to create all this, or to turn into a thin sheet of reflective foil to put in space in a static position at the Sun to reflect all this radiation to generate thrust to move the Sun. Yeah, okay, okay, I'm with you so far. What are some things we might have to worry about when doing this, just to you know, concerns we should keep in mind while building a giant

space mirror. Um. Well, I would want to make sure that we take pains to to not you know, either freeze or fry the Earth with this mirror thing, because the these that the mirror would probably be somewhere near the orbit of the Earth in order to make the materials stable. Um, we wouldn't want to melt the mirror either. That would be pretty bad. Um uh. And and having it relatively near by could potentially cause problems with um.

The the amount of solar radiation that continues to hit the Earth, which we want, you know, we enjoy having sunlight here. It kind of drives the entire life cycle on this planet or can Conversely, we wouldn't want kind of extra radiation from the mirror to start hitting the

Earth and fries completely. Yeah. I've seen some different considerations that different thinkers have had on what sort of the final heat situation would be with one of these in place, because there are different ideas about where you can put it relative to the Sun and the Another thing I think we should consider is how fast could this thing actually go and what are the conditions that would control

its its speed capabilities? Yeah, we we mentioned this earlier, and and I wanted to put into into actual numbers exactly how slow this thing would be going UM because okay, okay, if the Sun is already moving at some five hundred thousand miles per hour UM, that's an incredibly rough estimate, you guys, Um, the first few million years of UM scoutof thrust could only change our trajectory a little bit. UM. One thermodynamicist by the name of Virile bad Askew or

something to that extent. I'm sorry I didn't look this up before the podcast. Um. He's he's from the Polytechnic University of in Romania says it could take two hundred million years for us to change the trajectory of the Sun by as much as a hundred and thirty light years. And that's that's on the generous end. He He also said that it might be by as little as thirty light years. That's I mean, that's a big window. But

then again, thirty light years is a long way. I saw that note you made, and then I was trying to figure out, well, what's within thirty light years? Uh? I found a website called soul Station. I'm not familiar with the source, so I don't know if it's entirely accurate, but at least based on what they say, there are a hundred and fifty celestial objects within a twenty light year radius of Earth. So a lot of these are brown dwarfs and stuff that really wouldn't be useful to us.

But it listed at least to a sequence and seven G sequence stars, so I don't know. I mean, I could see even within thirty years, you could get to a reasonable number of objects out there. Thirty light years yeah, yeah, um over there. I mean, it's just just that number two hundred million years is a number that I have a hard time comprehending. Yeah, it's also worth thinking about it in the context of one billion years until the oceans boil. So sure, you know it's zebra children. Got

to keep him in mind. We can't forget the zebra children of the future children Okay, alright, have such huge eyes. They will they'll be adorable. Um. Okay, so so, so all of these problems are kind of sad news for anyone who is hoping to build one of these mirrors like next week. Um. But they also do offer a really promising implication, and that is that any alien civilization that could have possibly created one of these could be

pretty easy for us to spot. That's right. So there was a recent paper by Duncan h For again of the University of St. Andrew's, and he talked about the possibility of king for alien stellar engines as evidence of alien life. So we talked a little bit about looking for aliens in our episode on the Kardashev scale from January. But here's Forgan's idea. It goes pretty much like this. We already have astronomical projects that are looking for the

transit of exoplanets across other stars in the galaxy. So you have a telescope stare at the light produced by a star, and then you try to observe changes in that light produced by the star to see if it would be consistent with a planet passing between us and the star and blocking part of its light. Of course, an alien civilization that built a megastructure like a Scattov thruster might also be detectable in the same kinds of data.

So in a paper called on the possibility of detecting Class A Stellar Engines using Exoplanet transit curves, Forgan tries to model the kind of light curves we would see if we were observing exoplanet transit on a star that had a Scatoff thruster. So though the probability he rates of finding evidence for one of these things based on the methods and data we have available now is pretty low, we might have a more optimistic outlook once we compare

this strategy with other directed tools for SETI. Yeah, anyway, I thought that was pretty cool. Even if we can't save our own planet with a scout Out thruster, we could at least maybe use it to know that there are other civilizations out there that are more proactive than we are. Yeah. Yeah, Although, speaking of saving our planet, I wanted to discuss a couple other reasons that we might have to do such a thing. Right, So, even maybe before our planet swells into a red giant or

boils the oceans. In a billion years, we might really need to move our sun around. Yeah. Yeah, there are a couple relatively smaller reasons for this. Um. So, Joe, have you have you ever been worried about an asteroid or comet hitting the Earth? That is exactly the reason I've been hollowing out a cavern under my house to dwell in after the big one hits. We've got canned food, We've got lots of VHS tapes of sci fi movies from the eighties. I think we'll be good. A zebra. Yeah, Okay, Well,

I've got a new source for your paranoia. Okay. Interstellar gas and dust clouds. Oh it sounds dusty. It sounds not terrifying at all. Actually, But what's important to keep in mind here is that, Okay, space is not all space, not all empty space. There's some stuff out there. There's lots of stuff. In addition to stars and planets and all of that, there are these giant clouds of gas and dust that are floating around in the interstellar medium

between star systems. These things could count for as much as fifteent of the matter visible um visible across the electromagnetic spectrum. Not that like you can see with the naked eye, um, in our Milky Way galaxy. And according to one Michael Richmond of the Rochester Institute of Technology, that's some ten billion sons worth of stuff. Yikes, bunches

of stuff. That stuff in question is mostly molecular hydrogen with just a tad bit of helium and dust for for for lack of a better word, just just little microparticles things. Um. And yeah, none of that is terrifying. Um. But if we happened to go through one, it would be bad. Through one cloud of a cloud of the stuff,

it would be bad. Yes. And if you are shaky on the whole good bad thing, um, let me explain bad with a shout out to Jeffrey Winter's who wrote a really good piece for Discover magazine back in two thousand eight called how a cloud of space dust could wipe out life on Earth. Yay, okay, let's hear it all right. So the Solar system is surrounded by the heliosphere, right, Um, that's that thing that the Voyager satellites passed through well

a while ago, but we found out about it recently. Um. And and it's a protective wall of solar wind which is plasma that's radiated out by the Sun. Um. It's magnetic at the edges, and it helps keep the planets in our system safe from from interstellar particles and radiation. And and the thing is, astronomers think that we've been in a really clear section of interstellar space for the

past five million years or so. Um. If we were to hit one of these clouds of gas and dust, it would bombard our heliosphere, pushing it from from way outside of Pluto's orbit down into the orbit of of like Saturn or Uranus. Yeah. Um, And we're not super

sure what effects this would have on Earth. UM that the heliosphere would probably still protect us from a bunch of this cloud, but some of it would probably reach the Earth and the hydrogen that that composes most of the cloud could start seeping into our atmosphere and reacting with our oxygen, which would change our air supply for

the worse for us certainly. UM. And furthermore and more cosmic rays would be hitting the planet, which would endanger um, you know, our stuff and our people in orbit, and also greatly increase our radiation exposure here on the ground. So bad times. We do not want this to happen. Um. Unfortunately, these clouds are really hard for us to spot. We do know that there is one less than a trillion miles away, which is approximately two d and fifty times

the distance from Earth to Pluto. If that helps. It doesn't really help me, to be honest, but it's a good number, um uh, which which which means that we could collide with the sucker in only two thousand, five hundred years. Oh, that's pretty soon. That's that's way sooner. Probably can't build a shut up thruster. Hey, don't don't underestimate future human zebra. Okay, maybe maybe sure, get that fleet out there, tear down Mercury. Nobody cares about Mercury.

Get it done right, right, Okay, So we could at least, say maybe maybe possible, assuming all this works is as planned, that would be a very good reason to have one of these things active. Oh but then again, you know, it does take a while to get it started moving in the in the direction, So I don't know, but at least maybe we we can have one in time

to dodge the next one. Yeah, And furthermore, there's other stuff out there that we that we do need to be tangentially concerned about such as close passage to another

star system. Oh yeah, yeah, so so astronomers, uh, whose job it is to this kind of thing, have been projecting nearby stars paths out into the past and future, some ten million years each because why not, of course, Yeah, you want to know where stars are going to be, and they found that in the past ten million years, it's pretty likely that no stars have passed closer than three light years away from us. Okay, but in only thousand years, Uh, Proximus Centauri and Alpha Centauri could both

be inside that range. Yeah. Um, so what happens when a star gets close to us, Well, we're not sure, but it could be close enough to disturb another feature of interstellar space, which is the conjectured or cloud, which is the uh supposedly is the icy band loosely connected to the Solar System and is where comets come from. Right, It's what goes way way out there into the darkness, and we can't see the stuff in it always. Yeah. Yeah, it's it's maybe about halfway between us and Proximus Centauri

right now, so it's it's pretty far out there. But but comets and can come down into into the range of the Solar System, and the disturbance of this cloud could send a lot more comets down into the Solar System, sort of like just kicking sand into our face. Yeah, basically, except it could be deadly sand. Deadly comets, sand Man, Yeah, giant, giant, specially deadly because it sounds like comic sands. I'm sorry I said that, but let's let's keep it and move on.

I agree there. There are also other than that, um uh, brown dwarf stars to worry about, which are also pretty difficult to detect, and at least hundreds of them are within a hundred light years of us UM. In the nine eighties, there was even a theory that Earth's periodic mass extinctions are caused by a star in loose companionship with the Sun that swings by every like thirty two million years or so. I don't think that's correct, actually, I but most scientists agree these days that that that

that was wrong. Um. They were calling the star Nemesis. Oh yeah, Nemesis. Yeah, I've heard, Wait to Nemesis. I thought Nemesis was also a planet or is that planet x Nibiru? I am not sure. I do know that star trek Nemesis was a thing that happened. We need to get Ben and Madden here to talk about all of the secret planets they don't want us to know about. Well, not that Ben and Matt don't want us to know about,

but they they don't want us to know. Yeah. So so there are many many reasons why, you know, you know, and all all of these potential dangers will probably come into clearer focus as our detection equipment improves and and and as we crunch some of those numbers that we have already received from some of our telescopes and etcetera. But uh, yeah, I think I think it's safe to say that we have totally solid reason for wanting to

be able to move our solar system. And if out of Thruster is the way to do it, I say, let's start building today. You know, how do we get those robots to Mercury's Let's let's get a team of people on it. Somebody's got to build the robots first. Well, one thing I do want to be clear about is that the kind of stellar engine we've been talking about is not the only kind of stellar engine. In fact, as you probably heard of saying it's a Class A

stellar engine. There are whole other types of megastructures that have been proposed for harnessing a huge amount of the energy of a star, and hopefully we can in other episodes talk about some of those, Like you may have heard of Dyson spheres, which have a great name. They have nothing to do with vacuum cleaners. They have everything

to do with cosmic power, real cosmic power. Yes, uh and yeah, yeah, those those are Class B, and there's also a Class C. And we have already talked for quite a while today, so I think that we're going to leave that for another day. Uh. But in the meanwhile, if you would like to hear anything specific from us other than about more stellar engines, let us know. You can write us an email at f W Thinking at how Stuff Works dot com, or you can find us

on Facebook, Twitter, or Google Plus. Our screen names there are submitteration of f W Thinking. You can check out f W thinking dot com for lots more video and podcast and written content. Uh. You can also chastise me for using the words content out loud. And we hope to hear from you, and you will hear from us again very soon for more on this topic. In the future of technology, visit forward thinking dot Com, brought to you by Toyota Let's Go Places,