This episode was recorded live in St. Louis, MO at the Astronomy Cast Solar Eclipse Escape 2017. Listen as we discuss how humans might be able to colonize the Milky Way!
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Alpha Centauri Wikipedia page
Mur Lafferty’s Six Wakes
Scott Sigler’s Alive series
Arthur C. Clarke’s Songs of Distant Earth
Old Man’s War by John Scalzi
Transcription services provided by: GMR Transcription
Fraser: Astronomy Cast Episode 455: Your Practical Guide to Colonizing the Milky Way.
Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain. I’m the publisher of Universe Today. With me – and I got her title in front of me – is Dr. Pamela Gay, the Director of Technology and Citizen Science at the Astronomical Society of the Pacific and the Director of CosmoQuest. Hey, Pamela. How you doing?
Pamela: I’m doing well. How are you doing?
Fraser: Good. So, we are here in St. Louis two days before what is either a wonderful and triumphant eclipse journey or your third rain eclipse.
Pamela: So, I already got trying to kill everyone out of my system by taking a few bicyclists on the highway by accident because I missed a right hand turn. So, hopefully, my attempt to kill four people sacrificially will have cleared up our karma.
Fraser: Oh, really?
Pamela: This is my hope.
Fraser: Okay. Is that what our dark gods require is some kind of bicycling accident?
Pamela: I am abandoning you on the day of the eclipse in hope that my bad luck does not rub off on the group.
Fraser: We’ll see the rain off on the horizon and that’ll be Pamela carrying it away from us.
Fraser: For a skeptic, scientific podcast, we sure get downright superstitious in this kind of situation, don’t we? Alright. So, we are doing a couple of live events here. So, for those of you who are listening to this after-the fact, again you will know whether it worked or not. For those of you who are here watching us live, you’re gonna roll the dice with us.
So, today we are going to be talking about colonizing the Milky Way and really science fiction has misled us and really ruined our brains in so many ways. It’s taught us that if you want to colonize or visit other star systems in this galaxy, all you have to do is just hop in your warp-powered spaceship, cross for a couple of weeks, arrive, use your transporters, go down.
It’s very, very easy. But, the reality, of course, is that the laws of physics are a lot more difficult than science fiction has taught us but, at the same time, we just want to know how we’re gonna get to live on other worlds. So, today, we’re gonna just ruin science fiction Christmas and explain in excruciating detail how the laws of physics conspire against us and yet how it might be possible to colonize other words.
Pamela: And the thing that you should all know is I didn’t know what the topic was going to be until five minutes before lunch and I spent my entire lunchtime running errands. So, you get to see what happens with an unprepped Pamela.
Fraser: Not only that, but she doesn’t know what I’m gonna ask.
Pamela: That’s true.
Fraser: People are like, “Oh, how do you do your scripts? How does she know all the –” “There’s no script. She doesn’t know what I’m gonna ask.”
Pamela: It’s an oral exam every time.
Fraser: So, props to Pamela for having all this knowledge inside her brain. Alright, Pamela, so first let’s imagine the science fiction books that we’ve read, Star Trek, Star Wars, all of these things, and this galaxy spanning civilization of worlds and planets and outposts and starships that pass in between and the fact that you can be on one world and then you can move to another world. How is this all super wrong?
Pamela: Time. So, the biggest issue is it will take generations to get from one world to another. Even if we’re able to figures out near light speed acceleration, you’re gonna have to decelerate. It’s gonna take distance to accelerate. It’s gonna take distance to decelerate. You’re still probably looking at at least decades to get to the nearest worlds. So, you leave young. You leave with your children. You get there old and your kids are taking care of you.
Fraser: Yeah, but is there anything practically in the laws of physics that actually prevents us being able to travel from star to star?
Pamela: Patience. I’d say psychologists would say patience.
Fraser: Right, right. So, some of us might not have the patience to make this journey, but in theory, you can go from one world to another less than speed of light. You’re gonna be able to make that journey.
Pamela: There’s a few things that we’re still trying to figure out. If you go back and listen to our episode – or series of episodes actually – on Critters in Space, one of the things that we learned was things don’t reproduce so well without gravity. They tend to like not have heads and things like that and we like heads. That kind of is how we think.
Pamela: So, we have to solve why is it that things don’t reproduce so well in space or we have to solve how do you rotate things in a useful way to create at least enough gravity that everything born has heads.
Fraser: Right, right. so, I guess what you’re getting at is that you’re gonna need to create some kind of artificial gravity for the journey that – if you’re gonna have living creatures – that you’ve got some kind of rotational space station, your classic Pamela take a metal asteroid spin it up, live on the inside, make that journey. But what kinds of time frames – with the laws of physics as we understand them today – are we looking at?
Pamela: So, for the nearest worlds which as near as we can tell aren’t exactly habitable – So, we’re looking at things out near like Alpha Centauri. We’re looking at probably decades rationally and then we start looking at centuries once you start looking at the things that are currently looking potentially like they could support life maybe – maybe.
Fraser: But I mean you say decades, but the Voyageur spacecraft right now are gonna take 50,000 years at their current speed as the fastest objects leaving the solar system.
Pamela: I’m not saying we have the technology yet. I’m saying science allows it.
Fraser: Yeah, yeah. So, I mean let’s look at that scale first, right? You’ve got these spacecraft that are gonna take tens of thousands of years to get from us to the nearest worlds – the nearest star systems – which probably suck. So, I mean how could you even keep machines rolling, generation ships –
Pamela: So, the model that you see a lot in sci-fi because these people actually talk to scientists when they write their sci-fi – really do this if you write sci-fi – is they consider foundry ships, factory ships, ships that have the capacity to recycle metal, reengineer things, rebuild things, and thus potentially upgrade things as you go.
So, imagine you start with some of the most brilliant minds in the world. You have solved whatever it is that breaks things when they’re in the process of breeding in space and hopefully you end up with multiple generations of super smart people, who are bored on a spaceship and need to keep themselves busy by advancing technology.
Fraser: But I always think about the ethical issues sending off a generation ship and you know it’s gonna take say 50 generations to get to its destination and you’ve got that group of people who willingly go out on the spaceship to leave on this journey and you’ve got the 50th generation that gets the exciting job of landing at the destination and the 48 generations in between – whose only job is to procreate and die – like no one signed up for this. They didn’t volunteer for this.
Pamela: But science fiction offers some interesting ideas that again it looks like technology is heading towards. So, one idea that was in Mur Lafferty’s Six Wakes was we have amazing 3D printing technology. We’re working to figure out how to successfully print skin. We want to figure out how to print organs. Eventually, we’re gonna be able to print a body and there’s already a crazy Russian dude who’s planning to transplant heads. I’m not sure how I feel about that. In fact, I’m sure how I feel about that.
As we advance this technology, imagine a future where you’re allowed one real body and that’s your real life. That’s the one that’s allowed to procreate and things like that, but then to limit overpopulation – which we’re gonna get anyways – but hey this is why we’re colonizing new worlds. You can then download your brain pattern into a new body or perhaps take the “I am Bob. I am Legion” answer to things. I love that book title and I love those books.
So, you take the strategy of you download your brain into some form of a quantum computer and, in this case, you have either individuals that have signed up to live way “that expletive” too long – you also see this in Scott Sigler’s Alive series – or you download yourself into a computer and this is a few people who’ve agreed to live too long in order to get there with everyone else either downloaded to memory ready to be printed into new bodies or in stasis of some sort.
Fraser: But isn’t this just us trying to come up with clever ways to make the journey, for it to be human beings? But isn’t the more rational solution to this is to let our robotic – eventually overloads of course – but our robotic servants in near term make this journey for us to these other worlds to settle them, to explore them, and then maybe get back to us if any place is worth visiting? By the time, of course, we will be their slaves or merge with them if we’re lucky or be their pets and then they can decide what they want to do with us.
Pamela: So, this is where we start looking at all sorts of weird ethical dilemmas because at what point does an artificial intelligence become an artificial consciousness? Is it better to ask a willing human to download their brain into a suitably advanced computer versus creating an artificial intelligence that is trapped inside the computer?
So, you have to make that ethical decision of do we create our robot overlords and then send them off to explore in isolation inside computers they did not choose to be in or do we take that person who wants to be the explorer and download them into our spacecraft? These are the kinds of weird, weird ethical dilemmas we’re going to have to figure out as we consider this kind of exploration.
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Fraser: So, I think this idea of these generation ships, sending robotic ships, the slow boat way to do this where you may take – maybe we can come up with some kind of self-repairing spaceship power with vast stores of fusion or maybe it’s bringing in fuel as it moves along on its journey and it refuels itself and you keep the whole machine going and maybe it can handle that 10,000 year journey to a nearby star. What kinds of options do we have to make that journey more quickly?
Pamela: Yeah, quickly we don’t have yet.
Fraser: What’s our best – because I know the breakthrough Starshot group that are trying to send these little Nano probes at ten percent the speed of light to nearby stars.
Pamela: So, mass is really the great defeater. The more mass something has, the more energy is required to accelerate it. So, to make the kind of technological breakthrough that we need in order to send self-replicating anything, you’re suddenly talking serious amounts of mass. As you’re dealing with more and more massive things, the idea of using solar sails starts to become self-defeating. This is why airplane carriers have never been powered by sails.
There’s just some things that don’t make sense and solar sails have it way worse than sailboats because sailboats you have the big air molecules hitting those sails and driving the sailboat. With solar sails, you have light. Now, we’re all sitting here getting slowly roasted in this greenhouse of a room and we feel the light as heat, but we don’t feel it as momentum. We don’t feel the energy of the photons hitting our body. But, if we go outside where I can see leaves moving, we can start to feel the momentum in the air. So, light can move little tiny things. It’s not gonna move foundry ships.
Fraser: Right, yes. But there is a really interesting theory – and we’re gonna do an episode on this at some point – talking about fast radio bursts and these quick blasts of radio waves that astronomers are finding. One of the ideas for what could explain this is that they’re these vast laser arrays in other star systems that are zapping some kind of spaceship – like a big solar sail spaceship – with enough energy to be able to have it make that journey in a reasonable period of time.
Pamela: Our planet doesn’t have quite enough energy right now to do that. We’d need to harvest our entire solar system.
Fraser: Yeah, the calculation was it would take twice the surface area of the earth to make a solar collecting array that was capable of generating the laser pulse that would send a spacecraft on that journey.
Pamela: That’s not a moon. That’s a death star.
Fraser: But we’re in my imagination land and so we get to have solar arrays twice the size of the earth. I mean that’s peanuts compared to the Dyson swarm that I’m imagining right now. So, you could, in theory, again scale up this idea of some kind of solar sail to get higher velocity transportation between worlds and use–
Pamela: So, the only real problem with this is you have to decelerate and so you accelerate it using light when it is most massive and then you send it with enough fuel to slow itself down on the other side. Now, the problem is what if something wants to come back? It may not have the energy to do it. You may have to stay there long enough to build the lasers.
Now, there’s an interesting science fiction book, Aurora by Neal Stephenson, that gets into the idea of a generation ship that gets partway out and he’s was like, “And we’re done.” And they’re trying to contact the new generation of people living in our solar system, trying to get them to turn on the lasers to break them because they’re coming in hot. There are certain things you don’t want to come in hot and a really big generational starship is one of them.
Fraser: Well, and you can kind of imagine that, right? If you get your spacecraft accelerated to ten percent the speed of light and now you’re making that journey and congratulations, you don’t have to be born, live, and die and then for 48 generations you get to make the trip all on your own, but you are going to be hurtling towards your destination at ten percent the speed of light, which is bad.
Pamela: Is bad.
Fraser: And you can’t slow yourself down. So, you would need some kind of existing facility – the reverse version of that laser that accelerated you – on the other side to slow you down and you would have needed those suckers on the generation ship beforehand to have made that journey – or the robots – to set up that break before you set out on your journey. So, it kind of imagines this slow journey first–
Fraser: Robots, yeah
Pamela: Our robot overlords that we’ve hopefully not made so smart that they resent us.
Fraser: Right, the robots first. They colonize and set up all of the facilities that we require and then we follow with the kinds of spacecraft that’s far better for human beings. But those kinds of high velocities – you’re going ten percent the speed of light through space. How’s that on your–
Pamela: It’s bad. It’s bad.
Fraser: Yeah. What kind of navigational hazards might one experience?
Pamela: So, if you think about it, every single hydrogen atom you hit hurts. You really need to figure out shields at this point. You need to figure out some sort of an electromagnetic field that will happily deflect all the particles before they have a chance to hit your ship and hopefully – when they hit this electromagnetic field that we do not know how to produce but science fiction writers understand is necessary–
Fraser: Shields up.
Pamela: Yeah. Hopefully, they figure out how to do that in a way that when the particles hit the field, they don’t suddenly start emitting gamma rays and x-rays. There’s a lot of issues that need to be worked out because anything you hit – It is the same thing for me to hit a hydrogen atom at a tenth the speed of light as it is for the hydrogen atom to hit me at a tenth the speed of light.
Now, we do periodically have this kind of thing happen. We call them cosmic rays. They can break up your DNA. Luckily, we get hit by so few of them it’s not a big deal, but if you’re purposely traveling through space – through a molecular cloud “Oh, my God, die.”
Fraser: Yeah. One of the interesting ideas I think it’s Songs of Distant Earth I think it was. They talk about putting a big block of ice at the front of your spaceship, right? So, the ice will absorb all of these impacts and also serve as your water and serve as your fuel and all this. It’s a great idea except ice that you’re trying to accelerate to a significant fraction of the speed of light is a very difficult thing to do. So, on the one hand it’ a great idea, nice shield.
On the other hand, accelerating a gigantic kilometer wide block of ice to ten percent the speed of light requires a significant amount of energy. But let’s imagine that these get figured out and we’ve set our robot explorers. They’re moving ahead of us and they’re setting up these laser transmission systems. They’re building gigantic rail gun systems that accelerate to a significant portion of the speed of light and then you zip out and then you get caught on the other side and get decelerated again. It’s a beautiful, magical, future universe.
Pamela: All of the electromagnetic fields – all of them.
Fraser: Yeah. Yeah, exactly. Yeah, you harness the power of a magnetar to run your rail gun system.
Pamela: I’ve never seen that in sci-fi and I really want someone to write that.
Fraser: I just made it up. You plug into a magnetar, run your rail guns no problem. So, what would be the limits and the complexity of such an empire, foundation, federation?
Pamela: So, one of the problems that you run into is things move on straight lines in this situation except where things are now, they won’t be in the future. So, you have to send the robots over there because over there will end up straight in front of you in however many decades.
So, you have to take all these motions into consideration and really hope that some asteroid that we haven’t discovered yet doesn’t end up halfway through your journey in front of you and so really doing this without destroying yourselves and taking into consideration all of these different three dimensional motions and the extra distances that you need to go to get the robots to where the thing will be in the past. But, when they leave earth, that thing isn’t where they’re – all the motions are evil – all of the math, all of it.
Fraser: So, do you see this kind of a future? Right now, obviously, we’re wondering whether we’re gonna make it another week.
Pamela: Decade? Yeah, that too.
Fraser: It’s understandable, but let’s say we do. Is there any limit? I mean we are on our way to building more and more energy and more and more resources here on planet earth. We’re gonna run out of energy. Colonizing the solar system seems feasible. It’s not impossible. We’re gonna be able to start mining asteroids and settling other worlds. Do you think we’ll stop at the solar system or we will try and reach out to other places?
Pamela: It depends on – this is gonna sound horrible but – it depends on our breeding habits. At a certain point, you need enough people to support your civilization and we’re starting to see issues where in Japan, they simply don’t have enough of the younger generations to take care of the older generation. But then we see other places in the globe where you have significant overpopulation. So, you have –I read way too much sci-fi – you have books like Old Man’s War by John Scalzi where you see people from the overpopulated parts of the world going out and being the colonists on unoccupied planets – only colonized the unoccupied planets.
And then you have the people from the more unpopulated nations. The only way they can get off the world is in their old age when really we don’t have resources to take care of them. If our population globally starts to resemble Japan, I’m not sure where we find the humans to colonize beyond our solar system. But, if we have a burst of people saying, “I shall over reproduce. I shall produce three humans for every two humans.” At that point, with that kind of growth, then you can start to imagine having enough people to say, “I’m gonna send 10,000 people over there now.”
Fraser: It’s a funny thing, but most people remember when it was five billion humans and when it was seven billion humans and are we at eight now – more?
Pamela: No idea.
Fraser: Yeah, we’re almost eight billion humans. We’re gonna peak out at like 11 billion humans and then the numbers are gonna decline after that pretty precipitously and a lot of people are really happy about that, but other people it actually will eventually be a problem.
Pamela: And it also depends on the time scales that we’re able to advance this technology. Our earth is going to get unlivable somewhere on the next 100 years to 50,000 years, depending on how well we handle greenhouse gases.
Fraser: Right, yeah. And even if we don’t, the planet will become unlivable in about half a billion to a billion years, thanks to the sun heating up.
Pamela: Well, 50 to 90,000 is where we start ending up with too much water vapor in the atmosphere and so by 50 to 90,000 years from now, we need to have either killed ourselves off – which hopefully won’t happen – or figure out how to get somewhere else.
Fraser: Really? That quickly?
Fraser: Wow, I thought we had a little more time.
Pamela: Well, the planet does, but the situation that humans need before we start dying from being baked–
Fraser: Right. Right. Well, the cockroaches and the tardigrades will get us on lockdown. They’ll figure it out. Let’s talk about communication because one of the other fascinating things about this is that you’ve got this civilization where trying to communicate from world to world is gonna take you years to be able to send information back and forth. Imagine trying to browse a webpage on Alpha Centauri and have to wait four years. You type in www.AlphaCentauri and then wait and you go away and four years later, your webpage comes back.
Pamela: So, I’m sure someone local owns that domain by now.
Fraser: Someone’s already got the domains for all of the stars in the Milky Way, yeah.
Pamela: Yes. So, this gets to the really interesting idea of how our societies and languages and genetics going to drift apart. We already see that English and American English and Canadian English and Australian English are different languages where we think we’re speaking the same thing and we’re not.
Fraser: What are you talking about?
Pamela: I wear ski caps. You wear toques.
Fraser: Yeah, that’s true.
Pamela: I deeply confused a friendly British person – whose name I’m not going to share because I don’t know if he’d like that – by asking if he wanted biscuits and gravy. But in the UK, biscuits are cookies.
Fraser: Cookies, yeah.
Pamela: There’s certain things you don’t put gravy on.
Fraser: But you can imagine this sort of far future. I mean I totally get that. There’s this future that what it even means to be a human being has drifted away to the next version of what we have here on earth to where they may not even be able to interbreed–
Pamela: Higher gravities, lower gravities.
Fraser: Lower gravities, yeah, yeah. That’s all been handled quite well in science fiction, but it’s a fascinating concept to think what will human beings – if we can pull this off – what will human beings look like a million years from now, five million years from now, a billion years from now?
Pamela: Big heads.
Fraser: Yeah, gray aliens and they’re gonna go and visit other worlds. It’s a funny thing. We, as human beings, have been around in our modern form for what 100,000 to a million years maybe at the most and yet we imagine in our minds that we will remain forever, that we have this existential crisis about what’s gonna happen in the black hole era septillion years from now.
Pamela: But even in the last 100 years, we’ve changed ourselves as a race as nutrition has changed, as the way tall people are more likely to reproduce and we keep getting taller. So, as we get taller, as the ideals of beauty change such that now we’ve realized it’s okay to breed a woman who isn’t small, frail, and likely to die in childbirth.
So, we are changing ourselves as a species the same way we’re changing pugs. If you look at a pug from 100 years ago, they actually had a snout and longer legs and were much healthier dogs. Just as we are changing the way dogs look by breeding for our ideals of perfection, we’re changing how humans look by breeding for ideals of perfection and given the fullness of time and the changing ideals, we could become anything.
Fraser: So, place your bets. What do you think? What do you think are the chances that we are going to set up some kind of permanent existence somewhere else in the solar system; self-sustaining permanent existence?
Pamela: I think we will create self-sustaining permanent existence somewhere else in the solar system and those people will breed to be really short so that they use less resources and – as we become the mole men of Mars and mole women of Mars, we can safely escape the radiation in tunnels that aren’t that tall.
Fraser: And then what do you think about actually colonizing or settling other places in the Milky Way? Do you think that’s gonna happen? Do you think humans will be the group that does this?
Pamela: If we effectively figure out artificial intelligence and stasis units or 3D printing of humans and being able to transport consciousness, I think we can do it. I think we’re starting to grapple with the ethical concerns of generational starships and how three generations down the line may not want to be going somewhere else. I’m hoping that ethics will come to be the thing we listen to in the future.
Fraser: One’s kind of a really interesting idea about this is that we here on planet Earth live on a generational spaceship, right?
Fraser: That we are traveling through space. We go through generations and none of us are too grumpy about being brought into this world.
Pamela: You have teenagers. How can you say that?
Fraser: Sure, sure. Yeah, they’re fine. So, that’s the other possibility is that we just build some kind of solar thruster and move the sun and bring the planets with us and travel to other places–
Pamela: The sun has a bit of mass. It would be really hard to accelerate.
Fraser: There’s a way to do it. There’s a way to do it. Yeah. This called a Scadoff thruster. You build a big mirror. You build a big mirror on one side of the sun and then the sun hits it with – the mirror is attracted to the sun, gets brought in – the sun is pushing out its solar radiation which keeps it in perfect balance and the sun actually acts like a thruster that you can – over the course of billions of years – move the sun anywhere you want in the Milky Way.
Pamela: I need to work that math on that because it just feels like it won’t work.
Fraser: Talk to Scadoff. It’s not me. Yeah, yeah. But the math has to be figured. The acceleration starts slow but, over the course of a billion years, you can pretty much move the sun under its own power pretty much anywhere within the Milky Way. You can imagine this future civilization just reorganizes all of the stars in the Milky Way to a shape that’s easier to get to, easier to explore. Anyway, I like those odds. I’m willing to roll the dice. Thank you so much, Pamela, for going down my imaginary rabbit hole today and thanks to our live audience for joining us for this episode of Astronomy Cast.
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Duration: 33 minutes