That’s the story here, two science-fiction authors disagreed with each other about colonizing the galaxy, and you can stop reading now, because it’s all fuss and bother about a fantasy. Except, I would argue, that the disagreements and advocacy of their respective positions have consequences, and I agree far more with one than the other.
Kim Stanley Robinson wrote a novel called Aurora about a failed effort to colonize Tau Ceti with a generation ship. It’s pessimistic: complex engineering projects fail if you try to keep them running for centuries, the biology of small populations fail predictably if you have limited genetic diversity and limited environmental information, human societies are messy and fragile and tend to fall apart over time, and biology is complex and unpredictable and your destination is either going to be dead (which isn’t good) or teeming with independently evolved organisms (which is worse). He wrote the novel in response to a weird-ass initiative from NASA called The Hundred Year Starship.
In 2011, NASA and DARPA (the Pentagon agency that gave birth to the internet) lent their names to a project called The Hundred-Year Starship. Its aim was to coalesce the space community behind a goal of launching an interstellar mission by your time: 2112. For generation ship dreamers, it was like Christmas had come.
And then along came Kim Stanley Robinson to stomp over all our dreams and tell us that Santa Claus didn’t exist.
Robinson is best known in our time as the author of the Mars trilogy (Red Mars, Green Mars, Blue Mars, all written in the 1990s, the latter two set in your century). He’s what they call a hard sci-fi guy — he talks to the experts in the field, reads the latest research, does his level best to get the science exactly right. For example, all of his novels set in the 22nd century feature a flooded, post-climate change Earth. (Again, we’re really sorry about that.)
Watching a Hundred-Year Starship conference incensed Robinson. “It was a combination of a scam and a religious meeting,” he says, “presented with such an authoritative sheen, such pseudo-science.” So he went to NASA Ames, discovered a lot of internal consternation about the agency’s involvement with the project, talked actual planetary science with actual planetary scientists, and published Aurora in 2015.
I sympathize. It is a scam. There is a range of such ridiculous projects that are cheerfully supported by people who should be much more responsible. It ranges from the starry-eyed optimism of people like Seth Shostak, who want to pump money into SETI with exactly the same mindset as people who buy lottery tickets every week, to malignant rich assholes like Elon Musk who think the Earth is doomed to become an ecological hell-hole, so they are eager to get off this planet to one that is already dead. He sees trouble coming, and his response is to invest in the most expensive, futile tomb he can imagine. And unfortunately, that imagination is fed by overly optimistic science-fiction writers.
I like science fiction, myself. I also think it can be valuable in inspiring people to think about the future. But I would like people to be inspired about ways to solve real problems — we have lots of them crashing over us right now — rather than imaginary bullshit, like how we’re going to get to and colonize a planet we haven’t even seen. There is a place for that, but it’s called escapist fantasy, and there’s nothing wrong with it, unless you lose track of reality and muddle it up with real-world issues.
I will remind you that what inspired Robinson’s novel was NASA and DARPA supporting the idea of building a generation ship to carry humans to another star system 10 or more light years away, to be built and launched in the next century. Elon Musk isn’t going to build a viable colony on Mars, yet we’ve already got people day-dreaming about voyages that could last centuries, launched to destinations unknown, as if that has a chance in hell of happening. At the rate we’re going, the starship collapse Kim Stanley Robinson imagines in his novel is more likely to occur on a grander scale right here on Starship Earth, and we aren’t going to rocket away from it, no matter how many physicists and fantasy authors close their eyes and wish real hard.
That pessimism about space colonies annoys Gregory Benford, who wrote a negative review of the novel. It’s not a rebuttal of the ideas that Robinson advance, but really is just a review of where he thinks the story fails.
In 2012, Robinson declared in a Scientific American interview that “It’s a joke and a waste of time to think about starships or inhabiting the galaxy. It’s a systemic lie that science fiction tells the world that the galaxy is within our reach.” Aurora spells this out through unlikely plot devices. Robinson loads the dice quite obviously against interstellar exploration. A brooding pessimism dominates the novel.
Yeah, the review consists almost entirely of picking at plot holes in the book — which may be entirely valid flaws in the novel. He thinks, for instance, that Robinson “stacked the deck” by making the planet the starship arrives at implacably hostile to human habitation, which is the most likely outcome. The universe is not designed for us, so the majority of destinations are going to be uninhabitable! I think Robinson stacked the deck by making the imaginary starship actually succeed in arriving with a live crew at a distant star, which is already incredibly unlikely, and then being able to turn around and fly back to Earth. Unlike real life, I guess we can fix a plot hole in a book by just rewriting the planet so it’s a paradise.
Then I notice why Benford is disagreeing with Robinson — he’s the editor of an anthology of stories based on that silly conference!
Now I have a dilemma. I’d kind of half like to read that book, but only because it would probably make me really angry at the “scam and a religious meeting” and pseudo-science aspects of it all. Do I really need that kind of negativity in my life? Maybe. It does keep the bile flowing.
You should know one of the Benfords (Gregory?) Wrote a retelling of the book of Mormon as space opera.
It’s the worst scifi I ever read. And I read one about a giant mantis where they make human giants to fight it.
I disagree with the lottery ticket analogy. In a lottery you pretty much know your odds of winning, but in SETI we don’t really know the odds at all. There are really only two probability statements we can make towards the existence of extra-terrestrial intelligences: 1) in the history of the galaxy we are probably typical and not unique, and 2) we haven’t found any ETs yet, so the odds of them existing right now are less then they were a while ago, at least in our neighborhood. You could argue that civilizations do not last long enough to discover each other, but I find that too nihilistic to contemplate. You could say something similar for early Bronze Age civilizations, but we still look for them, and find them. Is the looking wasted effort?
Unfortunately, NASA has a lot of engineers who believe passionately that they are working to “get humans off this rock.” I make it a point to devastate their dreams whenever they wax a bit too rosy, which is always. Thing is, they will never debate you on the science, because none of the science supports them. They will just mumble, mumble “Wright brothers”…mumble, mumble “they said space flight was impossible…” mumble, mumble “visionaries…” …
I respond with:
1) Space is really, really big.
2) Matter cannot go faster than the speed of light, so any voyage to another star will take centuries, because space is really, really big.
3) Moving matter rapidly through space is really, really expensive.
4) Carrying everything you would need to survive for a century or two would be prohibitively expensive.
5) Complex systems break down and we fragile beings need complex systems to keep us alive.
6) And even if your complex system didn’t break down, galactic cosmic rays would shred your DNA before you left the Solar System.
Earth is our home…our only home. It is the only place that will support us. How about a science fiction novel where we learn to care for Earth?
2)
Ursula K Le Guin wrote a rather good novella about a generation ship ( the title escapes me for the moment). Thinking about it, it was more about us here and now than spice travel though.
Spice travel? That was Dune wasn’t it?
Vreejack, there’s another possibility:
Space is really, really big. Broadcasting a signal in radio waves is very costly and by the time it reached us, would likely be too difficult to distinguish from noise. A narrow beam at the right wavelength is much more likely to reach its destination and still contain information. But because a narrow beam is directed, ET has to be selective where it gets aimed. They are much more likely to aim it to regions where stellar populations are dense (e.g. near galactic center) than where they are sparse (out in the exurbs where we are). Given we’ve only been sending out radio waves for a century or so, there is no reason why ET would prioritize us.
I’ve noticed that a number of Sci Fi writers (mostly male ones) start to think that the world works the way it does in their stories, and that the only reason it doesn’t is because people are too stupid or perverse to go along with it. They’re like the guy at a bar with other guys who knows everything and insists on convincing everyone of it, by the volume of their arguments if the “logic” doesn’t.
I’m reminded of a line from a story I like:
I can see the utility of generation ships. We are running out of places to get rid of superfluous heterosexuals to already
PZ, why are you always stuck on these things? Why are you so bitter? You’re so often harping on these rich pricks and their INCREDIBLE WASTES OF MONEY ON FANTASY JOYRIDES AND CHARLATAN’S LIES and it just sort of gets old. I mean, it’s beyond a cliche at this point. So’s your fixation on the impossibility of all these things. I mean, I get not buying Musk’s Mars colony hype, and I get not believing there will be starships in a hundred years, or several thousand. But some of this is obviously not hype. Barring the dissolution of the company, SpaceX is clearly going to be flying rich people around the Moon in a few years. It will eventually become routine, and they’ll be able to try other stunts, and some of them will work. But here is the crux of the problem, PZ. Even if you do not see it, you are operating on the assumption that we know all there is to know about spaceflight & technology, and that even a million years from now, humans will remain limited to the Earth. Well, forever is a long time, man. And in a million years, today’s problems will be irrelevant to whether or not starflight has succeeded, with the sole exception of if humanity has gone extinct. Hell, if you put the time horizon far out enough, literally any problem might be solved. You’d have to prove a thing physically impossible to really discount it, and thus far you have not. Why, look at what might come out of the biological sciences in the far flung future! They might even be able to genetically design brand-new organisms from scratch!
You said KSR wrote his book to criticize the idea of the Generation Starship. Yeah, it’s kind of a dumb idea…today. But so is imposing modern limitations on such an endeavor. We will literally not be able to afford interstellar missions until our society is so advanced that the cost just doesn’t matter. So griping about the ludicrous pipedreams of starstruck fools in the present is pointless. It’s even detrimental, i.e. your bitterness. The proper thing to do is to ignore it, to not take them so seriously. Musk might have named his male-chauvinism-phallic-symbol the “Starship” but it’s anything but. No one is actually going to build a true starship in our lifetimes, even if someone has enough money to try. So why get mad over it? And the joyrides that almost certainly will happen are not going to be enough to doom humanity, and if you want to get cynical, consider it a grand lottery in which the occasional rich prick gets to buy the farm, yuk yuk!
One last thing: in the past you’ve praised sending robots to explore the solar system, but I feel that doesn’t comport well with your hostility to human spaceflight. Sure the robots are cheaper, but they’re essentially doing the same thing: interesting science of little practical benefit to us. (The only real practical benefit would be to prepare eventual human missions!) We are lucky to be living in a society that can easily afford tossing a few tons of ironmongery through the void every year to satisfy our curiosity. The argument that the many fans of space exploration should give up on their fantasies, that they should just stop asking “Why can’t I go?” or “Why can’t I live vicariously through someone else who gets to go?” is truly missing something. And the thing that argument seems to be missing is a grasp of actual human nature.
Yes, I am cynical about it all. But if you’re going to get upset about the tiny minority of people who protest at the fantasies of the glib privileged few who influence all the money and planning for the future, I get to be pissed off at the delusional polyannas who get sucked into supporting nonsense and the evasion of responsibility.
Oh, and I do support robots, because they work, while humans in space don’t. Those are perfectly compatible views.
Vreejack:
Why’s it supposed to be likely that we’re “typical”?
And what does that even mean? Typical with respect to what? I guess you could say some very general (and useless) things, like for example we’re certainly (not just probably) “typical” in the sense that we’re made of matter and not antimatter. But beyond a few things like that, I don’t think we have any good evidence telling us something more interesting/informative.
How long ago was “a while ago”? (Not clear what “our neighborhood” is either, but I’ll leave that aside.)
If you mean not so long ago (when astronomers had telescopes, etc., which could have found some evidence), then I don’t see how the odds were higher then. We have much better equipment now and many more people doing much more informative kinds of astronomy. We’ve also now spent more time looking — the galaxy is a rather large place to search, after all. So it should if anything get better, not worse. Right? (To be clear, I don’t mean the chances of some alien species existing, which we simply don’t know, but that we have better chances of finding evidence now than we did then.)
If you mean they were only around in the very distant past (before people were even attempting to “find ET”) and are now extinct, I don’t know why that’s supposed to be considered likely either. There is an incredibly long period of time in the future when life could still exist somewhere, because the stars won’t all be burnt out yet and so forth. (This also bears on your statement that we’re “typical,” since there’s no good reason to think we happened to evolve at a “typical” time in the life-permitting part of the universe’s history.) The point is, if you think billions of years of the past sounds like a lot, that’s tiny compared to the amount of time that’s left. And if you’re just picking a random one out of a hat, you almost certainly wouldn’t pick this particular 100-year period that we happen to be living in right now.
Frankly, I don’t think we’re terribly likely to find anything in the first place. Maybe it’s just me, but that’s where I’m starting from. The fact that we’ve spent some decades (very little in the big scheme of things) not finding evidence just isn’t too surprising or impressive, so I don’t think we could pull any big conclusions out of that…. It seems like we know pretty much the same as we did before, and ignorance just doesn’t teach anybody anything.
This argument kind of reminds me of C.J. Cherryh’s Alliance-Union novels from the ’80s and ’90s, where space colonization does succeed…but life in space is such an ugly, uncomfortable, despotic, dismal hell of bad food, cramped, smelly habitats, ever-present danger, despotic rule by political dynasties masquerading as tech corporations, and eugenic clone slavery that, despite all the characters sneering at the masses back on Earth who never went with them and seem to have not “advanced” beyond 20th century lifestyles (they’re never directly shown and no book is actually set on Earth to my knowledge), one can’t help but think the people who stayed behind were the smart ones, whatever their purported religious ignorance or cultural backwardness. Beyond the obvious things I just mentioned, one thing that struck me about the setting is the paranoia and total social alienation of basically everyone in space, people who have lived a role in a totalitarian technocracy for so long that they cannot even imagine a real community, let alone live in one.
If we could build a generation ship and it worked, would anyone really want to go?
PZ left out a few relevant facts here.
.1. Gregory Benford has some major qualifications. He has a Ph.D. in physics, and worked for decades in astrophysics and plasma physics.
You can be sure he knows science.
.2. Gregory Benford is one of my favorite writers.
He is a good writer of science fiction novels.
I’ve probably read most of his novels.
You can be sure he knows physics.
Kim Stanley Robinson is one of my favorite writers.
@johnm55, # 4: Have you read “Rocket Ship Galileo” by Heinlein? I has the same premise-a ship travelling for centuries, and the crew develops mutations from radiation during the voyage and eventually turns to cannibalism.
You are thinking of “Orphan of the Sky”. (https://en.wikipedia.org/wiki/Orphans_of_the_Sky)
Harry Turtledove wrote two short stories – “Herbig-Haro” (https://summerblizzard.tistory.com/87) and “The Road Not Taken” (https://en.wikipedia.org/wiki/The_Road_Not_Taken_(short_story), https://eyeofmidas.com/scifi/Turtledove_RoadNotTaken.pdf) in which it turns out that anti-gravity and FTL travel is something that can be done with 16th century technology…if you know how. Earth is invaded by the Roxolani, who form up rows and fire their blunderbusses at the crowd around them The results don’t go well for the Roxolani and humans get the two most powerful technologies that they had inexplicably overlooked. I like the universe that the stories create because it is so blatantly obvious that it is a fantasy.
2112? Rush fans?
I’m quite sympathetic towards the idea of space travel and colonization, but I think it would be a big mistake to underestimate just how massive a project it would be. If we could build a functional generation ship that could actually survive the trip to another planet (even a close one), it would be the single biggest achievement in human history.
And that’s before we start on the discussion on terraforming and actual colonization; just getting people there alive would take more ingenuity than literally anything else we’ve ever done. I mean, we haven’t yet figured out how to make a self-sufficient space station in orbit that can support even a handful of people and for colonization, you’d need thousands.
And honestly, even if generous aliens showed up and handed us such a functional generation ship, we would probably still run into problems of a social nature. Humans aren’t very good at building stable societies. If we can’t live in peace here, how are we going to manage on a space ship? Once we have a society here on earth that can go a century without devolving into warfare, then we can talk.
loosenoodlepoodledoodle: Did it ever occur to you that maybe we should be devoting some of the resources these rich playboys are devoting to thrillseeking to maybe resolving some of the problems on the fricking planet so that our species? This is not just some frivolous lark. It is expensive.
LNPD: “Barring the dissolution of the company, SpaceX is clearly going to be flying rich people around the Moon in a few years.”
Says who. The government has to sign off on every launch, and SpX has a LONG way to do before their safety is up to standards of commercial flights for the FAA (the relevant regulating agency).
LNPD: “Even if you do not see it, you are operating on the assumption that we know all there is to know about spaceflight & technology, and that even a million years from now, humans will remain limited to the Earth.”
No. We’re going based on what we KNOW about spaceflight and about physics. Those limitations are not likely to change any more than the fact that you can’t fly an airplane that ignores the Bernoulli equation. And I agree that in a million years, things will be different, but the most likely difference is that humans won’t be here–or if we are, will exist in small bands of hunter-gathers eking out a tenuous existence on the inhospitable rock we have created.
LNPD: “Sure the robots are cheaper, but they’re essentially doing the same thing: interesting science of little practical benefit to us. ”
Wrong! NASA missions are illuminating critical aspects of planetary science–and in doing so, the science of our own planet. Understanding how the planets formed has practical applications for everything from climate change to seismology and mining. Some of these missions may one day lead to actual mining of the asteroids–which could dramatically increase the supplies of platinum group metals, increasing the availability and reducing the cost of things like catalytic reactors… Overcoming the limitations of sending out probes has led to breakthroughs that have generated billions in economic growth. Even today $1 spent on NASA leads to over $3 growth in the national economy.
For an enthusiast, you don’t know much about spaceflight.
How about this: Tell me your plan for how to keep ten thousand people alive for a century on a floating ship right here on earth. Don’t just hand-wave. Show me schematics of the ship; show me living quarters, bathrooms, factories, farms, and schools; show me all relevant numbers for energy use, water use, and food production. Hash out every last little detail.
It should be easy. You’ll have breathable air, sunlight for solar panels and gardens, and the possibility of fishing to supplement the food supply. I’ll even allow you to dump trash in the ocean (for the sake of argument, don’t actually throw trash in the ocean). It’ll be child’s play next to space.
When you can do that, then we can discuss your ideas for space travel.
@3 Snarkers!
Well said! Sending biology into the void makes no sense. Yes, I love science fiction. True story, in the 4th grade I used to sneak into the Adult Section of the library to find science fiction books. The librarian finally got tired of chasing me out. That said, you gotta admit those Klingon babes are hot! But I digress.
Going out on a limb, I will suggest that the chance of biology starting and evolving like us, that is, the Class M Paradise Planet is ZERO. So, we’d be stuck in our artificial environment forever. Better yet, how about a program to develop better machines for exploring space and send those guys out, you know, like Veeja and Nomad?
LykeX@#20:
How about this: Tell me your plan for how to keep ten thousand people alive for a century on a floating ship right here on earth. Don’t just hand-wave. Show me schematics of the ship; show me living quarters, bathrooms, factories, farms, and schools; show me all relevant numbers for energy use, water use, and food production. Hash out every last little detail.
I’d pay $49.95 for a game based on that premise. Sort of Rimworld goes to space. Decide who gets eaten, etc. be careful not to racist! Oops now the engine room crew is “seceeding” from the ship. Etc.
Here’s a classic game that features how things can go wrong in a space ship:
Awful Green Things From Outer Space
I think that one of the biggest obstacles to generation ships would be keeping the crew alive long enough to get anywhere. Because, the inevitable reaction of humans cooped up together for long periods are suicide or murder, sometimes both.
I mean, I can’t even stand flying from Philadelphia to Cleveland.
And, @13, I will point out that that’s not going to change no matter how advanced the technology.
raven@13: Generation ships may be physically plausible (or at least not forbidden by current physics), and that’s something I would expect Benford to know about.
The problems are biological, ecological, and sociological, and those fall outside of his area of expertise. That’s not necessarily a bad thing, but handwaving past those problems completely is.
@profpedant, # 16-Oops, my mistake. Thanks for the correction.
@ Snarkrates, # 19: Isn’t the Bernoulli equation more related to fluid mechanics? I could be wrong…
I’ve read Aurora, and I agree with Benford’s criticism. I had two main problems as I was reading the novel, one technical and one philosophical.
The technical problem was the deck-stacking that Benford mentions. This is a society with the godlike ability to recycle any substance down to its constituent elements and build it up again at the molecular level, yet they can’t find a cure for an alien disease? That gave me trouble suspending my disbelief.
The philosophical problem was that I watched Moana around the same time, and I kept thinking about the parallels with the Polynesians as I read. Just like the space colonists, they packed up their families into outriggers and sailed towards new lands out of sight over the horizon. Surely it was dangerous; surely many of them died. That’s been true ever since Africa.
Robinson seems to argue that we should surrender that part of our heritage as humans, but I’m not buying it. Heck, that isn’t just our heritage as humans, it’s something we share with every species on earth. Every species from spiders to sequoias sends out colonists to hostile environments that might not survive.
Where I do agree with Robinson is that right now, we need to pour all of our expertise and wealth into stabilizing our climate and saving ecosystems from being wiped out. But I don’t have a problem with sf writers dreaming that, someday, we may achieve that goal and start on something new.
brucegee @27, I haven’t read the book, but for what you describe as recycling any substance down to its constituent elements and building it up again at the molecular level, we can do that now, it’s just chemisty. I mean, that’s what I do.
It’s trivial to take something down to its elements. Separating the elements and building them to something else, is also pretty easily done, depending on what you want to build. Both just cost a lot energetically, and can be pretty slow, which is why we don’t do them on an industrial scale now.
And, well, the Polynesians had a lot more going for them. They knew (or at least supposed) that there would be air to breathe and fish and the like to eat and survivable weather the whole way. They took a chance on there being any land to find, and having enough water to get there, but it’s not the same as knowing that you’ll have to survive for hundreds of years without the slightest support from the environment and, in fact, the slightest contact with the enviroment being fatal.
I meant to say, curing any disease, not to mention alien ones, is an awful lot more difficult. Biology is notoriously gooey and complicated, and total control over it is way more difficult.
christoph @26: Air is a fluid.
My own guess is that living planets are numerous but not common; and that of those living planets, most bear only microscopic life. And I am highly skeptical that there is any intelligent life anywhere in the universe, including planet Earth.
For evidence, I cite the radio emissions from planet Earth. Those emissions prove the existence of life on planet Earth, and even technological life, but intelligent life?
the thought that comes to mind first is “the b Ark” greaat idea we need one for all the fundy’s and anti-vaxers we can find
@9
you might be right if things stay the way they are now but there is no reason to think they will stay the way they are now. The reason there are rich people like Musk now who have all these grandiose ideas has everything to do with the way our societies and economies are set up and run.
there is an increasing imbalance here in the U.S and world wide between the economic classes. There is no reason to think that it will continue and there are many reasons to think that it will change the question is really how and when not if.
why is it we have to follow the will of the few and not the needs of the many. What makes some individual’s vision so important when the vision is mostly dreams with some bordering on hallucination with regards to the “laws of nature”.
While it may be theoretically possible to colonize other distant star systems we will never do that until we have mastered colonizing this one way more fully then we have, even now we have no actual plans only slim sketches for any development, we can not even coordinate with the systems of this planet and are teetering on disaster today . I do not think we will do any of that unless it is the will of the collective either. great endeavors particularly of this kind of scale will need far more coordination and cooperation than mere greed and fear and dreams alone can muster .
@Rob Grigjanis, #30: Gases behave differently than fluids. For example, you can’t compress a fluid but you can compress a gas. Whether or not that would significantly affect lift or thrust, I’m not sure.
brucegee1962: “This is a society with the godlike ability to recycle any substance down to its constituent elements and build it up again at the molecular level, yet they can’t find a cure for an alien disease? That gave me trouble suspending my disbelief.”
The problem with this attitude is that it grossly under-estimates the difficulty of building up matter–it’s not just about building things up from the elements. It’s about building the compounds up with the right elements in the right order and in the right geometry/topology/chirality as well as having everything in the proper energy states. That’s where he’d lose me.
bruce: “Just like the space colonists, they packed up their families into outriggers and sailed towards new lands out of sight over the horizon.”
A wee bit different. The islanders could catch fish from their canoes. They could maybe hope for some rain to replenish their water supplies. Interstellar space travel? No such luck. I am afraid that physics, chemistry and biology don’t really care about whether we’ll be able to fulfill our “nature”.
christoph–that is why you have both compressible and incompressible fluids. Both are still fluids, and both still obey Bernoulli’s equation. Either type of fluid can give you lift. It all depends on the pressure on either side of the wing.
When things get interesting is when you combine compressible and incompressible phases. Multiphase flow really makes big messes (think “wet fart”).
Al you need is a young teenage crew ,along with a couple of tupperware containers full of Human precious bodily fluids ,plus a thousand or so human eggs ,can’t see any problem .
@johnm55 #4, you’re probably thinking of Paradises Lost by Ursula Le Guin (2002).
Benford has a Ph.D. in astrophysics. Robinson has one in English. Just sayin’.
There is a reason it is called science fiction.
As an engineer I fully agree that generation ships are infeasible, even setting aside the difficulty of accellerating a spaceship of the required size to a reasonable speed and slowing it down at the destination.
The longest stint at sea for a modern warship that I could find is in the order of 200 days. After such a long period sea, stores and replacement parts will be running low. A generational ship would spend dozens if not hundreds of years in space without a “port call” or resupply.
Look at whatever modern machine you like. How many of them will last hundreds of years without complete replacement? I suspect the number is a big fat 0.
Take for example relatively simple parts such as bearings, seals and electronics. No modern machine is without them. None of those parts will last anywhere close to a century in use. Even when perfectly maintained, bearings will eventually wear out. A 25 year old o-ring will like as not break when you try to disassemble the machine it is in for maintenance. And even if you take a 25 year old new o-ring from its packaging, it won’t last.
If you have a 25 year old piece of electronics, chances are you’ll have to replace failed resistors, capacitators and IC’s.
And all of these things are nontrivial to make. Every one of them require a large and diverse supply chain.
You might get bearings to last 100 years by rediculously oversizing them.
Maybe the same might go for integrated circuits. But I don’t think that there are elastomers that would last that long, even in storage. And the same goes for e.g. electrolytic caps.
In a comment on his blog, the sci-fi writer Charlie Stross wrote about the minimal viable size of a self-sufficient mars colony:
I would say that basically the same goes for a generational ship. Because it is a colony, just one that moves. That last sentence alone should give people pause. Can you imagine the size of the vessel suitable for transporting the whole population of Germany?
@40
not just the population but the entire economy supply chain for everything as well besides all of the environmental components that are not included in the calculations today.
There may be plenty of xenobacteria out there (in which case they should be protected species, no matter how humble they look) but the most likely explanation for the silent cosmos is that we are first in the Milky Way to develop technology.
.
Exoplanets- their colonization will be the domain of ‘strong’ AI. Those AIs will be our descendants as much as flesh-and-blood descendants. And they will not mind being dormant during a two-century journey, nor will they be deterred by extreme cold, or other quirks of the local worlds. As long as they volunteer, let them have the rest of the universe.
And if our descendants ask nicely, they might even decant and grow human embryos for us, once they have established themselves on the rare terrestrial worlds orbiting G and K dwarf stars we might consider human-friendly.
I’ve actually written a novella about a 4,000 year long interstellar journey. I avoided the entire generational thing using stasis (the origin of which is unimportant to the story) and used the plot device of waking the crew up every 1,000 years for a day’s break, explained as a psychological aid to help the crew adjust to the 4,000 year leap into the future their time in stasis necessarily involves.
I struggled for a reason as to why Earth would bother undertaking such a ridiculously expensive venture, and in the end I landed on a combination of discovering evidence of intelligent life on an exoplanet 40 light years away and the “Triple Threat” facing Earth’s population — global warming, Yellowstone’s caldera volcano about to blow its top, and worst of all, the Sun entering into an unstable phase potentially extinction level solar storms.
I guess my effort is considerably more optimistic than KSR’s — Earth survives and remains in touch with the mission, even upgrading the AI that runs the ship during the journey. Time is definitely a factor as the crew struggles to deal with jumping 1,000 years into the future every time they wake up, and witnessing massive changes back on Earth and on their destination planet (not for the better in the latter case).
If anyone is interested in reading it, it’s part of a collection of stories called: First Contact: Alien Encounters I published on Amazon a number of years ago, Kindle or paperback:
https://www.amazon.com/First-Contact-Encounters-Michael-Walker-ebook/dp/B00FQ8VDIO
The clue is in the title — the stories all revolve around making first contact with aliens (or them with us). One or two of them are on the silly side, but others are a little more thought provoking… I hope!
(This is the first time in years I have promoted my book anywhere online, so why do I feel so dirty…?)
I touch on that in my story, mentioned in my previous comment. The mission is a lifeboat mission (a hedge against extinction) so it is crewed by human beings, but the ship itself is run entirely by an AI which is constantly upgraded throughout the mission and by the time they reach their destination, it’s very much in charge of everything, simply because it’s the best equipped to make the right decisions, and the same thing is being replicated by other missions launched later.
If our society is still a hybrid AI and human one in that distant future, I wouldn’t be at all surprised if the best run colonies were those left in the hands of the AIs.
One problem with a generational ship is that the second generation could be extremely pissed off at the idea of being stuck in interstellar space their entire lives and decide to turn the ship around…
Space 1999 springs to mind… :)
rsmith @40
The problem with arguments about generation ships being impossible is that they’re obviously not: we’ve been living on one just fine for 4.5 billion years or so. (And, aside from some really stupid decisions from the idiots currently captaining this rock, there’s no reason we couldn’t continue to do so indefinitely.)
So what it really comes down to is an argument about the hypothetical minimum viable size of one, under some hypothetical technological limit, and whether that size ends up being small enough that it’s feasible to accelerate towards someplace interesting afterward.
That might seem like a quibble, but I think it’s critical. You’re talking here about “ports of call” and “spare parts”. But a generation ship isn’t analogous to a warship on a tour at sea. Rather, it’s a kind of minimally viable planet (or, indeed, a solar system — since it needs to take an independent, long-lasting energy source). The “generation” in generation ship means not only biological generations, but also mechanical and electronic ones. I think the operating assumption should be that every part would eventually be rebuilt and replaced along the way, perhaps many, many times.
So when your quintuple-great granddaughter or whatever is changing out an O-ring halfway through the trip, she’s no more likely to be using up some dwindling supply of crumbling stock from her quintuple-great grandfather’s time as you are when you change one. Just like you, she’ll be using new o-rings, made on-board from recycled or sustainably produced feedstock of some kind.
Which is easier said than done, of course. As you say, the stuff we use here on Earth tends to be at the end of an incredibly diverse, interconnected supply chain. There’s no way that set up could be transplanted as-is and work on any reasonably-sized generation ship or, e.g., Mars colony. The whole technological base and supply chain would need to be simplified, compactified, automated, rationalized. Reinvented from the ground up, basically. Probably whole new lines of technology and chemistry will need to be developed — like figuring out how to make all the necessary lubricants and polymers from sustainable agricultural feedstock or something instead of dinosaur squeezings. Preferably, in a compact module that doesn’t require trained operators.
I have no idea whether all of that is possible, or what it would look like in the end. It’s a huge unsolved problem, I think. One that the likes of Elon Musk haven’t even begun to grapple with, AFAICT. An interesting one though.
Imagine? Sure. People have imagined much, much bigger. “McKendree Cylinders” have something like the surface area of Russia inside. I mean, that’s a back of the envelope calculation, and construction is contingent on a supply of magically strong nanotubes, but you didn’t ask if I could actually build one…
It all kind of depends on the assumptions you make about living conditions and technological limits anyway. At the upper range of currently existing urban densities, something on the order of Germany’s population could just about fit in a couple of more conventional O’Neill cylinders. They’d still need a bunch more space for food and recreation and stuff, but it’s all very imaginable.
(And “Germany” as a minimum viable population seems unreasonably pessimistic, by at least an order of magnitude or two. Eighty million people is only about 20% off the population of the entirety of the Roman Empire (40M-50M) and Han dynasty China (60M) combined. I get that we have a few more technical specialties nowadays, but even so…)
Imagine? Sure. People have imagined much, much bigger. “McKendree Cylinders” have something like the surface area of Russia inside. I mean, that’s a back of the envelope calculation, and construction is contingent on a supply of magically strong nanotubes, but you didn’t ask if I could actually build one…
It all kind of depends on the assumptions you make about living conditions and technological limits anyway. At the upper range of currently existing urban densities, something on the order of Germany’s population could just about fit in a couple of more conventional O’Neill cylinders. They’d still need a bunch more space for food and recreation and stuff, but it’s all very imaginable.
(And “Germany” as a minimum viable population seems unreasonably pessimistic, by at least an order of magnitude or two. Eighty million people is only about 20% off the population of the entirety of the Roman Empire (40M-50M) and Han dynasty China (60M) combined. I get that we have a few more technical specialties nowadays, but even so…)
@#47, jack lecou
Wow, now there’s an intellectually dishonest misrepresentation of reality.
The problem you are conveniently ignoring is that our “generation ship” has a nearby star pumping energy into its ecosystem 24/7. If you could outfit the Earth with propulsion and use it to travel, even ignoring the fact that useful speeds for interstellar travel would strip the atmosphere, by the time the planet reached the same distance from the sun as Neptune the only living things left would be a few bacteria and a lot of hibernating tardigrades. A planet is not a generation ship.
@50
I would think the necessity of an energy source (like the sun) can be taken as understood. Indeed, quoting myself, just a few sentences later:
Maybe one ought to at least read the whole post before accusing others of “intellectual dishonesty”?
Aside from uncharitable and not-even-correct-pedantry, is there actually anything wrong with this characterization of our solar system? It even manages to move through the galaxy at a sedate but not inconsiderable clip — 200km/s would get us to Proxima Centauri in just a few thousand years, if we were pointed in the right direction.
@45- tacitus
There’s the whole issue of the second generation not having consented to the horrific predicament the previous aholes put them into. Yeah I’d be ready to mutiny in that case, especially if I was just a conduit for a third generation and was hopelessly stuck on a boring ass generation ship.
Jack:
Yes. A ‘ship’ is something crafted.
In what way is that a useful distinction here?
The argument is that it is impossible for human beings to traverse distances on the order of dozens of light years, on generational or millennial timespans, because their machines and biomes would inevitably break down.
The counterpoint is that this kind of “argument from entropy” fails by observation. Any such expedition would necessarily depend on some source of energy, and that energy would be used to locally combat entropy, just as life does within the solar system.
If a self-contained bio-technological system can be made sufficiently sturdy and compact enough to be accelerated to some reasonable escape velocity (including a sufficient source of energy, natch) — and this is more or less the definition of a generation ship — then the whole system would work just like the Earth-Sun system in microcosm. “They will inevitably run out of parts” is not an argument against such a voyage anymore than it is against the existence of Earth-bound civilization.
There’s nothing magical about who or what made the conveyance or the energy source that saves that argument. Entropy is entropy and energy is energy.
(Which is not to say there aren’t other arguments: there are some very big speculative ifs in that hypothetical to attack, if you’re inclined. But arguing, say, “anything big enough to be self sufficient will be too big to practically accelerate”, or “the onboard civilization will forget its purpose after a few millennia” are very different, more interesting, and much less flawed points to base
a discussion on, than “there are no hardware stores in space, so entropy will inevitably break all the coffee machines”.)
Heh. https://en.wikipedia.org/wiki/Pierson%27s_Puppeteers#Homeworld%E2%80%94The_Fleet_of_Worlds
I seriously doubt we’ll be traveling to the stars anytime soon, but it’s an interesting challenge. It’s hard not to think of the current fascination with generation star ships and 15 minute cities as related. Getting them to work requires answering a lot of the same questions. What do adults and children need to live and thrive? What needs to be produced and distributed? How much labor is needed in a community? What environments promote mental health? What is the best way to make collective decisions? The list goes on and covers a broad range of fields, technical, political, scientific and philosophical.
The current boom in private sector rocketry is a triumph of NASA’s original remit. For a long time, NASA was way out in front, but it drove a broad range of industries, and now the private sector can take advantage of them to make things like rockets, alternate power generators, comfortable leisure wear and so on. It’s like Eli Whitney getting funded to build muskets with interchangeable parts. His son and Sam Colt delivered over 30 years later, but 100 years later you could go to the hardware store and buy mass produced spare parts specified by numbers. Another hundred years and the idea is so basic one rarely thinks of it.
Personally, I’d rather have billionaires spending their money on racing space yachts than buying out politicians to suppress the minimum wage. So, there’s that.
…very different, more interesting, and much less flawed points to base a discussion on.
It occurs to me that what often irritates me about these kind of discussions might be generalizable:
What it usually boils down to is that arguments about the (im)possibility of Hypothetical Thing boils down to the (im)possibility of several constituent enabling technologies, A, B and C.
So, for example, if we were having this discussion 150 years ago, and the topic was “powered human flight”, maybe A is a wing that generates lift, and B is a propeller that generates thrust, and C is a light, powerful engine. Reasonable people could certainly disagree about the prospects for, say, C. The issue is that if you’re a “C skeptic” there’s a right and wrong way to present that argument, and the wrong way is a really easy trap to fall into:
The right way is to present arguments that actually address the substance of C, drilling down to explain why you think it’s hard or impractical (“steam engines just don’t have the power to weight ratio you need, and there’s no conceivable advance in materials science that could change that”).
The wrong way is to say something like “without C you won’t even get off the runway” or “air is just to hard for engines to push propellers through”. In other words, begging the question. Worse than the fallacy, the way these things go, you’ll be confusing the issue by restating something that everybody had, at least implicitly, stipulated up front: Of course you can’t get off the ground without the right engine. Duh. Everyone agrees that any hypothetically viable aircraft will need a solution for A, B and C. But rather than concretely arguing against C, you simply assumed it out of existence, and now everyone will end up going in circles.
unclefrogy 33
We can add in the people whose favorite response to pandemics is to demand obsessive sanitizing of all surfaces, since that’s been scientifically shown to be useless with the current pandemic.
It’s interesting to see two of my most respected sf authors taking opposing sides on this issue. For the record, I think Robinson is correct on the shorter timescale (i.e. the next few thousand years), but Benford might be correct on the longer timescale.
And to those who keep saying Benford is right because he is a physicist, while Robinson is wrong because an English major, please STFU. This is an appalling example of the argument from authority. Kim Stanley Robinson goes to extraordinary lengths to get the science right in his stories, and in my experience is more scientifically accurate than most of the “hard sf” writers I have read because most of those writers are only good on their specific area of expertise while assuming knowledge of other fields. I can’t count the number of times I’ve been reading a physics-centred hard sf novel that suddenly dived into a deep crevasse of idiocy on some point of biology.
And in this novel, the issue that Robinson raises is NOT physics anyway. From a physics point of view, his humans succeed admirably. They travel to Tau Ceti. And then they engineer an entirely new propulsion system that gets them successfully back to Earth. Saying that Robinson’s story arc is wrong because he doesn’t understand physics is about as sensible as saying the Pequod would never have sunk if Melville had understood materials science.
unclefroggy@33, lumipuna@58,
Don’t forget that the entire population of Golgafrincham was wiped out, after the exile of the telephone sanitisers, by a pandemic started by a dirty telephone!
Well strictly speaking, not indefinitely – and without some large-scale engineering, not even as long as life on earth has already existed. As the sun shines brighter over time, the earth will probably become uninhabitable in something like 1 billion years. A nice sunshade might stave off disaster a few billion years more.
I enjoyed Aurora, as I have most of KSR’s work that I’ve read (but not all: the latest, Red Moon, is plain tedious). Benford’s review is primarily political in motivation, as the recurrent swipes at Marxism/collectivism and concomitant praise of markets indicate (Benford seems oddly to have overlooked the abundant evidence that capitalism is unsustainable) – but since Aurora itself clearly has a political message, that’s fair enough.
I tend to agree that generation starships are a practical impossibility, absent some fairly fundamental discoveries in physics (not FTL travel or violations of the conservation of momentum – I’m convinced those are simply impossible, and I wish more “hard SF” writers would try working within those constraints, but sources of energy beyond anything currently envisaged). But I’m not convinced by the idea that such a closed travelling system is impossible at much less than earth scale, given an adequate energy source. Sure, we can’t make one now, but I see no reason to assume we’re anywhere near the limit of knowledge relevant to doing so. However, if “we” do eventually embark on interstellar colonisation, I don’t think that’s the likely route. There are at least three other possibilities, in order of (in my judgment) increasing probability:
1) Large starships crewed by long-lived humans or somewhat modified humans – long-lived either through hibernation, or increased lifespans.
2) Medium-sized AIs.
3) Flocks of tiny machines, accelerated by powerrful earth- or more probably space-based lasers, in the manner of Breakthrough Starshot. Even this approach requires fundamental advances in materials science, for example to produce a sufficiently strong, light sail – but again, I see no reason to think current technologies are close to the Pareto frontier of scale, durability and capability. Sending out flocks allows for attrition by collisions with dust particles and cosmic rays. The first “generations” would be scouts, aimed at possible targets (themselves selected using future space-based telescopes far larger than the James Watt), and would whizz through those systems collecting and returning data. The next generations would use their sails, and the gravity of star andor planets (mapped by their predecessors), to go into orbit around the target star, self-assemble into larger units, and start collecting materials and building. I doubt whether this would at any stage involve settling on planets, or sending/manufacturing biological beings.
[KG, pretty sure that lumipuna was alluding to that]
John Morales@61,
You may well be right! I didn’t take sufficient note of the italicisation of the last 3 words.
The most frustrating thing about discussions like these is the absolute refusal of the technological optimists to do the fucking math. Their starting point is always:
Assume a source of infinite, clean energy. There is never the least thought given to what such an energy source would be–or if any source is proposed, it is just flat-fucking, pathetically wrong. (e.g. fusion)
The nearest systems with even a hope in. hell of having habitable planets are >10 light-years (~100 trillion km) away. Let us posit a trip that covers this distance in 2 millennia with constant acceleration (positive acceleration halfway there and negative for the remaining half–you do have to slow down, remember). You’d need an acceleration of at least 0.1 cm/sec^2–that doesn’t sound like much, but consider the mass). In order to protect the crew from radiation, the mass of your generation ship must be roughly on the order of Earth’s atmosphere–5.5 quadrilion tons, or 0.0001% of Earth’s mass. That comes out to ~5E29 J per year. Add in the energy needed to keep your spaceship habitable–at least hundreds of exajoules–let’s call it 10^30 J/year. That’s equivalent to fusing about 1.5 exagrams of hydrogen and harvesting the energy with 100% efficiency.
Good luck with that.
snarkrates@63,
Well, your figures (which could do with some justification, rather than simple assertion) don’t seem to place the thing beyond the bounds of possibility. In fact, they make me take the idea slightly more seriously. 1.5 exagrams is 1.5 trillion tonnes. Let’s say you collect 1% of the energy rather than 100%, that makes it 150 trillion tonnes. Still a lot less than the mass you assign the generation ship itself, so you’re not getting into the realm where the fuel accounts for most of the mass (even if you go to 0.1% energy harvesting efficiency). And is it beyond the bounds of possibility to collect 150 trillion tonnes, or even 1.5 quadrillion tonnes of hydrogen from the solar system? (I know that current attempts at controlled fusion require deuterium and tritium, which would make things a lot harder, but can we be certain that both controlled fusion of ordinary hydrogen, and the the collection or production of enough of the more easily fused isotopes, is out of the question?)
To be clear, I don’t think a generation starship will ever be launched, but I don’t think the possibility is as easily dismissed as you claim.
The most frustrating thing about discussions like this is incredibly sketchy justifications for how figures are chosen and calculations carried out.
I mean, 5.5 quadrillion tons is the actual entire atmosphere of Earth. Which is, you’ll notice, shielding an entire planet. Do you have some sort of justification as to why you’d also need that much for a single spacecraft? Even a really big one? The mass of atmosphere currently shielding, e.g., Germany is already three orders of magnitude smaller than that figure, even if you include both sides (which probably isn’t the most efficient arrangement).
(And that’s just using your own assumptions. IIRC, air isn’t the most efficient shielding material per unit mass in the first place, so there’s probably a better shielding solution even without speculating on advanced materials, selective shielding of different parts of the ship, drugs or genetic engineering to increase resistance, etc.)
KG@60
I agree about Red Moon. It lacked the plotting, character, and for that matter even the big science fiction ideas of his Mars trilogy. I haven’t read anything else by him so maybe I’ll try Aurora.
jack lecou@51
The first idea that pops into my head is a focused beam powered in your home solar system (like a laser sail). Energy doesn’t strike me as the deal breaker.
Still, feasibility aside, I have trouble coming up with a reasonable problem for which a generation ship is the answer. The technology required to build a self-sustaining system like that would be sufficient to build enormous habitats within your home solar system. You won’t have a practical reason to leave for a long time to come. If it’s just about exploration, then there are probably much better ways.
Disclosure: I don’t think the far future of an advanced civilization (advanced in age and capability, not intended as a qualitative judgment) is driven by its biological forbears, so the interstellar ships it sends will have no reason at all for a habitat resembling the home planet.
But assume for some reason we need to have biological human beings in a nearby solar system. Even James P. Hogan had a better idea in his novel/libertarian tract Voyage from Yesteryear (1982). You send genes in digital form along with artificial wombs and some means of early development and education. That’s also well beyond present technology, but not obviously harder than a generation ship. The payload is far smaller and more durable and can travel faster.
If any life form ever makes into out of their own solar system in any form (besides probes), I suspect they do it by bootstrapping. First send a self-replicating system with basic abilities for scouting necessary material and constructing a much larger base capable of universal manufacture and chemical synthesis. Once the base is established, continue all future “travel” at light speed by sending information. Build a biological habitat if that’s what you want, and populate it entirely from locally available matter. (If we find friendly ETs whom we trust, we don’t need to send any material payload.)
“You” don’t get to travel to the other star, but neither do you in a generation ship. The technology doesn’t exist yet, but neither does it for a generation ship. Unless the generation ship is an end in itself, it’s hard to see what it’s good for.
Assumption: we may get technology to make an AI/robot mission with von Neumann machines able to travel at 0,01 C.
Such expeditions would reach Proxima and Alpha Centauri A and B* in ca 400 years, Barnards star and that wossname brown dwarf in 600 years and the main price -Tau Ceti and Epsilon Eridani- in a little more than a millennium.
What will really take time is terraforming any terrestrial planets.
(And, yes if there is native life in any world, it should be preserved)
Looks credible without assuming crazy new ttechnologies s
* probabllity of a G star having a world that fulfills the criteria of being ‘habitable’ is 18% we cannot count of striking it rich at Alpha Centauri, but the AIs will have far more flexible criteria for what they consider suitable worlds.
That’s pretty much what I was thinking of as the sequel to my possibility (3) @66.
birgerjohansson@67,
Where does the 18% come from? Is that the chance of a “roughly-earth-sized-planet-in-habitable-zone”? Because I doubt if there are any extrasolar planets in our galaxy where humans could take their helmets off without expiring within minutes!
@KG & PaulBC:
I tend to agree re: small replicators of some kind.
But there is a possible catch there: radiation. The slower you go, the longer you’re exposed. The faster you go, the more stuff you slam into.
At the scale of journeys we’re talking about, either way the cumulative dose might be enough that even e.g., solid metal is going to be degraded. Keeping a little store of genetic information and robotic replicators intact through all that is a non-trivial problem.
In a way, a generation ship is (in the way I alluded to above) the only “proven” solution to the problem. But one way or another entropy and radiation damage will probably have to be actively, not just passively, combated on the trip. Maybe the solution is teeny-tiny generation ships, where the generations are little self-replicating nano-machines carrying redundant banks of information or something.
Re: 61 and 62
Yes, and I thought a joke about lethal pandemics with unexpected qualities fits in this thread rather well, since the B Ark was already brought up.
jack lecou@70
All right, but in that case, the answer is the same. You power it from your home solar system with a focused energy source (e.g. https://en.wikipedia.org/wiki/Laser_propulsion). Aside from active entropy reduction and repair, you can supply it with any lost information, so you don’t even need radiation-hardened storage, though you’d probably want it. It’s still a much smaller payload than a generation ship.
The need for a continuous line of sight is a little awkward, but “space is big” and any disruption should be intermittent.
As my mind wandered, I considered a scenario for a traditional generation ship. Suppose you have “settled” your entire solar system with massive, self-sustaining habitats all powered by solar radiation. One of them could choose to become a tethered habitat, similar to the others but powered by laser so it did not have to stay close to the home star. It could gradually move off at its leisure, at whatever is feasible, whether it is 0.01c or 0.001c. This seems wildly implausible, but I suppose it could happen.
There’s actually a lot of ‘stuff’ out there too, for certain definitions of ‘a lot’. With fusion or beamed power to keep you warm, it might be just about possible to sort of hop from Oort cloud object to Oort cloud object all the way out, until you find yourself in a different star’s Oort cloud. Then you hop your way back in.
There’s actually a lot of ‘stuff’ out there too, for certain definitions of ‘a lot’. With fusion or beamed power to keep you warm, it might be just about possible to sort of hop from Oort cloud object to Oort cloud object all the way out, until you find yourself in a different star’s Oort cloud. Then you hop your way back in.
Also:
Apparently about half a dozen fast-moving interstellar objects pass through the solar system each year. You could potentially just rendezvous with and colonize one of those, then go along for the ride. It’d be a matter of being ready to go, and waiting for one with the right velocity and composition. The idea being that it could provide a lot of the shielding, fuel and other mass you’d otherwise need to bring up to escape velocity on your own.
@ snarkrates, # 36: Thanks. I particularly like the “wet fart” analogy. : )
KG, the point is that you have to haul all that fuel with you from the start–that’s even more mass to accelerate. Also, I’ve made the assumption that the atmosphere alone is sufficient–we also have the geomagnetic field benefiting us.
Look, even getting to Mars is a challenge. Getting a probe to another star system might be just feasible (it would be a fly-by, not an orbit insertion). People are talking about technologies that are so vastly beyond the scope of anything we could even contemplate based on known physics that they might as well be selling fairy dust.
Frankly, the future of humanity is much more likely extinction than interstellar colonization. And we seem utterly incapable of resolving the much simpler problems that threaten that fate.
That’s the fun part, isn’t it?
I’d question “beyond known physics” though. Warp drives are beyond known physics. The point of speculating about something like a generation ship is that, as far as we know so far, it might not be beyond known physics.
YMMV, but I expect that’s exactly the point. For a lot of people thinking about a bright future like this that doesn’t include extinction is a way to plot a path through it. For example, figuring out how to cooperate productively on a grand scale goes a long toward toward solving both problems. In so many ways, these are not unrelated challenges.
jack lecou@78
I’m not disagreeing, but I have a slightly different take.
The question of interstellar expansion is fun to think about, and it just doesn’t matter to me at all whether humans, our cybernetic offspring, or ETs in this galaxy or elsewhere are the ones who do it. I feel safe in saying I won’t be around to witness it anyway (barring some major advances in life extension).
That doesn’t make it any less interesting a puzzle. Given that a post-scarcity* society (which I also won’t be around to see) would fit within the confines of a solar system the “why” is as big a question as the “how”. I think it would eventually be done, but probably just because it uses only surplus resources and strikes the collective fancy of such a society. It won’t be done out of necessity unless there is some actual necessity for it, which escapes me.
*Given some finite bound on population, but certainly very large, especially if sentient beings aren’t limited to natural biological forms.
@PaulBC
Yes to all of that.
Right. And maybe I should clarify that when I say “a bright future” I certainly don’t mean an individual future for myself, or any other humans currently alive. Like you, barring miracles, I expect I’ll have been dead for millennia by the time anyone seriously thinks about a manned voyage beyond the solar system. It’s about a collective future — the generations of humans still to come, and also our cousin life forms here on Earth (maybe not mosquitoes?) and any artificial or other lifeforms we might create.
I think whatever collective noun that is can be a bit of an impedance mismatch in these discussions. Some people are very focused on the here and now. Others prefer to gaze at impossibly far horizons and think of what ifs. Both perspectives have their merits.
Another way to put that might be that in such a world the mere existence of a viable “how” — assuming there is one — would obviate the “why”. If the fraction of people who might be interested in such a thing for its own sake is anything like it is today, then at some point the question would move to “why not?”, and then perhaps very quickly to, “when do we leave?”.
Vreejack@2: I disagree that we are more likely typical than unique. Statistically, there is a fair likelyhood that there are other intelligent beings in the galaxy. But as Stephen J. Gould said, humans are the result of “a staggering concatenation” of random events, so the likelyhood of humans being typical is small. In any case, it’s irrelevant, because the distances involved are so great that even communication is unlikely. And even if it were, unless ET e-mailed us the plans for a warp drive, we won’t be going anywhere anytime soon. We may as well resign ourselves to the fact that we’re stuck here and concentrate on fixing Spaceship Earth. As far as looking for Bronze-Age civilizations, it’s not a waste of time to look for something that we have a high degree of confidence exists.
Snarkrates @3: “How about… learn to care for Earth?” Now that would really be science fiction!
snarkrates@77,
But your own figures indicate that the weight of fuel would not be the bulk of the mass to be accelerated, and you haven’t answered jack lecou’s point about why you would need the whole atmosphere. Of course we should prioritise dealing with the huge crises that loom ahead of (and around) us, but that’s not relevant to whether ideas for interstellar probes/colonisation are outside the bounds of possibility. I think you have as strong an emotional commitment to dismissing them as the “Man has always…” crowd has to believing in them.
@KG:
Unless I misread, I think snarkrates’ fuel/energy figure is per year, which is indeed pretty brutal. Not only do you need to multiply that by ~2000 years, but also carry even more fuel to accelerate that fuel, etc. The rocket equation is a very cruel tyrant.
Even assuming a ship somewhat smaller than quadrillions of tons, this math is why most “realistic” (for lack of a better adjective) plans — including the one KSR postulates in Aurora, it sounds like — tend to assume something like a laser assist in at least one direction. And/or antimatter factories inside the orbit of Mercury chugging away for hundreds of years to make the fuel, etc.
There’s no question that interstellar travel would be a very hard problem to crack, in all kinds of ways.
jack lecou@85,
Hmm, I’m not sure – I assumed the assumed duration of 2,000 years had been factored in, but the text is not clear. I found the following in Britannica:
Let’s look at the deuterium-tritium reaction first. 1 tonne of deuterium would need to react with around 1.5 tonnes of tritium, so 1 tonne of the two combined in the right ratio would produce about 3.3 x 10^20 J. As I said, an exagram is a trillion (i.e. 10^12) tonnes, so 1.5 exagrams of this D-T mix would produce about 5 x 10^32 J, or about 500 times snarkrates’ 10^30 J. The H-H reaction (much more difficult to produce outside a star of course) produces about 40 times less, but two atoms of H weigh only around 2/5 of one D and one T, so the same mass of fuel would produce maybe 30 times snarkrates’ 10^30 J. In both cases, that’s the total energy produced, not the amount you could capture and use, but snarkrates’ figures assumed 100% efficiency, and in both cases, the 1.5 exagrams figure seems too high for the annual requirement, too low for the whole 2000-year voyage. But in any case, it’s only if the mass of fuel needed to accelerate and decelerate the “payload” approaches that of the payload itself that the need for extra fuel to move the fuel, the fuel to move that fuel, etc., threatens to increase the fuel needed by orders of magnitude. It’s quite possible I’ve made a mistake – maybe snarkrates will set out his calculations (and answer your point about whether the whole atmospher is needed).
@KG
Well, I didn’t check any of the math. It wouldn’t surprise me at all if your figures are right, and the 1.5 exagrams figure is wrong. And I obviously think a dry mass in the quadrillions of tons is beyond silly (ditto a shipboard population in the 10s of millions).
But I also think snarkrates is wrong about “technological optimists” not having done the math. I mean, some certainly haven’t, but many have.
Which is why think snarkrates’ other point, dry mass aside, is more or less correct in principle — even a really good fusion rocket would need to carry a lot of fuel. There are some numbers to play with there — you don’t necessarily need continuous acceleration, for example, and could maybe trade off a longer journey. But even so, the mass fraction might be pretty dire. Even crippling.
That doesn’t necessarily doom interstellar travel. It’s the whole reason we have such a fertile ground of other ideas like laser propulsion, or Bussard ramjets (which, alas, don’t appear to work), or micro probe swarms, etc. I don’t see any sign that we’re running low enough to be worried yet.
@KG
Well, I didn’t check any of the math. It wouldn’t surprise me at all if your figures are right, and the 1.5 exagrams figure is wrong. And I obviously think a dry mass in the quadrillions of tons is beyond silly (ditto a shipboard population in the 10s of millions).
But I also think snarkrates is wrong about “technological optimists” not having done the math. I mean, some certainly haven’t, but many have.
Which is why think snarkrates’ other point, dry mass aside, is more or less correct in principle — even a really good fusion rocket would need to carry a lot of fuel. There are some numbers to play with there — you don’t necessarily need continuous acceleration, for example, and could maybe trade off a longer journey. But even so, the mass fraction might be pretty dire. Even crippling.
That doesn’t necessarily doom interstellar travel. It’s the whole reason we have such a fertile ground of other ideas like laser propulsion, or Bussard ramjets (which, alas, don’t appear to work), or micro probe swarms, etc. I don’t see any sign that we’re running low enough to be worried yet.