The first conference devoted solely to worldships takes place today in London at the headquarters of the British Interplanetary Society. It seemed a good time to check in with Gregory Matloff, a man I described when writing Centauri Dreams (the book) as the ‘renaissance man of interstellar studies.’ Perhaps best known for his continuing work on solar sails, Matloff’s interests have nonetheless ranged widely. He brought deep space propulsion to a wide audience in his book The Starflight Handbook (1989), which covers the full spectrum of interstellar options, but for over three decades has continued to produce scientific papers investigating issues ranging from laser ramjets to beamed microwave missions. A recent interest has been the expansion of the human biosphere into space, as discussed in books like Paradise Regained: The Regreening of Earth (Springer, 2009) and the soon to be published Biosphere Extension: Solar System Resources for the Earth, written with C Bangs. These last titles indicate that the interest in worldships Matloff first cultivated in papers for JBIS in the early 1980s continues to burn bright, as the following will confirm.
PG: Greg, I know you have a paper slated for the worldship conference that the British Interplanetary Society is holding today in London even though you couldn’t be there in person. And I know you’ve also been drafted by the Benfords to give a talk at the 100 Year Starship conference coming up in Orlando in October. When I first surveyed the field for my Centauri Dreams book back in 2004, I learned you were one of the early voices on this intriguing concept, the idea that a spacecraft might become a vast habitat capable of carrying thousands, even hundreds of thousands, of people between the stars.
GM: I was one of the early scientific writers who addressed the idea. The concept itself goes back to the 1930s and even earlier. Worldships are mentioned in a philosophical essay by J. D. Bernal, The World the Flesh and the Devil (1929). There is also an absolutely wonderful science fiction novel by Olaf Stapledon called Starmaker (1937). He not only talks about world ships but also implies that stars themselves are conscious.
PG: The 1930s were an extraordinarily productive period both for science and science fiction.
GM: Extremely productive.There was a literary group at Oxford University that has become justly famous. C.S. Lewis and J.R.R. Tolkien took part in this, and Stapledon was often discussed. I would have loved to have been there to have heard these guys kicking their ideas around in the era before World War II, a time when they all knew what was coming. It must have been fabulous. The worldship idea then disappears, although Tsiolkovsky mentions it when talking about space greenhouses and things like that. He doesn’t really develop it, and nobody touches it to my knowledge until the 1970s.
Then came Dandridge Cole, before Gerard O’Neill comes onto the scene, talking about ‘macrolife’ and the possibility of hollowing out asteroids to create workable habitats. Gerard O’Neill himself is important because he takes the idea and makes it concrete. O’Neill had major people working for him, such as Brian O’Leary, who was an astronaut, and Thomas Heppenheimer, who becomes a well known space writer. Eric Drexler would became the co-founder of the field of nanotechnology. So these are very bright folks, and they worked with O’Neill on the space colonies. O’Neill somewhere in there quotes Stapledon, and Arthur Clarke refers to him as a true science fiction visionary. He’s referring to Starmaker.
Image: Dandridge Cole, who coined the term ‘macrolife’ to refer to human colonies in space and their evolution. Credit: Wikimedia Commons.
PG: Are worldships a theme in science fiction today?
GM: I found in the last 30 years maybe a couple of pieces, including Greg Benford and David Brin with Heart of the Comet (1986). People are hollowing out Halley’s comet and making it livable. The book also speculates about uploading of the human essence into a computer and things like that. What seems to have happened in science fiction in the last 20 or 30 years is to me many steps back. We’ve gone in the direction of military science fiction on the one hand and fantasy on the other. I go in looking for science fiction and would like to buy something but it’s very hard for me to find something in a Barnes & Noble that I’d like to buy. That to me is sort of depressing.
Looking Inward: Prospects and Consequences
PG: This seems to be a long way from the intense vision of the 1930s.
GM: Exactly. Now it is possible that we might be doing inward exploration rather than outward exploration. A recent book we purchased is How the Hippies Saved Physics, by David Kaiser (2011). The book talks about folks who started to apply quantum mechanics to human consciousness. It turns out C and I knew one of them fairly well, Evan Harris Walker, who died a few years ago. He was very much involved in this approach. I think what happened is that inward exploration, probably because of the 70s, had replaced outward exploration in many peoples’ minds. There may be some sense to it because people in the 70s thought they could do exploration by taking a pill or something similar. Later on learning how to do it by meditation and yoga comes to seem easier than funding a trillion dollar project to launch a few people into deep space.
PG: Just as setting up computerized VR is easier. Maybe we’re still going in the same direction.
GM: Yes, I think so. In fact, about two years ago, in October of 2009, C and I went to a meeting of singularity people. We were guests of Greg Benford. It was very interesting to hear these brilliant mathematicians talking about a virtual reality and folding human consciousness into it. Its a seductive thought. Now, is it more seductive than SETI? Is it more seductive than actually going out and colonizing new worlds or spreading the biosphere beyond the Earth — I don’t know!
I run into this with students all the time. Some of them are much more interested in inner exploration than outer exploration, and I don’t have any answers for this, except that I do hope that we also extend the biosphere, because I think it should be a goal of technological consciousness. It’s something we can do and it’s something we should do rather than having everybody just living in a little box. You and I may turn out to be in the minority on this.
Image: Olaf Stapledon, whose vision became a focal point for C.S. Lewis and J.R.R. Tolkien, and influenced Lewis’ subsequent science fiction, which was partly written in response to Stapledon’s ideas.
Near-Term Drivers for a Worldship
PG: Could be, but I suppose the worldship concept is sort of the ultimate extension of the expansion of the biosphere. Because these are gigantic vessels. Just how big are they?
GM: There are various estimates of the size of a worldship. If we’re talking about an interstellar ark, something that is like living in a submarine, it’s something that may be the size of a submarine. This is Edward Gilfillan in the 1970s [author of Migration to the Stars, 1975). He was an MIT professor emeritus. But O’Neill colonies actually make a lot more sense. The smallest of them would weigh on Earth about a billion pounds. It would house about ten thousand people, and would have a maximum dimension of about a kilometer. If you wanted to build one bigger that would be able to house a population of a hundred thousand, we’re talking about something that massed ten billion pounds up to a hundred billion pounds. I forget the exact number, but this is the O’Neill model 3, and that’s something like ten kilometers, roughly the size of Manhattan.
PG: These are obviously enormous constructs. What would be the drivers that would send us in the direction of building them?
GM: What O’Neill thought was that the main driver would be getting energy for the earth. He thought we would have to go out and mine the moon, and also mine the nearby asteroids to get material to build solar power satellites. And this is what the population of the space habitats would do long before they migrated anywhere. Unfortunately, technology has sort of caught up with him. He did this work in the 70s when solar voltaic cells had an efficiency of maybe ten percent and a thickness of about a millimeter, something like that. You needed a lot of material. Now the efficiency is something like 30 percent and we’re talking about 10 or 20 microns.
On the Japanese solar sail IKAROS, a couple of these hyper-thin solar cells are being tested. Here you’re talking about something that’s maybe 20 microns thick with an efficiency certainly higher than ten percent.
PG: And the tests have been successful.
GM: Indeed, very successful, and of course you have to hope they will turn out not to degrade with time. As it turned out in Aosta, the lead of the Japanese IKAROS team gave a talk and unfortunately he didn’t have any information yet about the degradation of these sails. Remember that it’s only been a year, but so far they are functioning perfectly. So they might function very nicely in the interplanetary medium. From the point of view of energy, that’s very nice because it means that particularly with the Falcon 9 Heavy, if the numbers of Elon Musk are correct, we might well be able to launch solar power satellites into geosynchronous earth orbit if they’ve even been manufactured right here on the earth. And these might, if they have a significant lifetime and good efficiency, even be able to make a profit. We’ll have to see about that.
This is very good from the point of view of terrestrial energy, but it’s something of a setback for the O’Neill colony. Meanwhile something totally unexpected is happening and that is space tourism. When you look at the way that it is developing, it’s extremely interesting. Already a few thousand people have signed up for Richard Branson’s Spaceship II at a cost of maybe $150,000 each to get ten or fifteen minutes of weightlessness. Other people, and I have no idea what the numbers are, are registering at the cost of a million dollars with Robert Bigelow, who intends to build a space hotel through his Bigelow Aerospace.
Now it could well be that we’re going to be in a situation in which somebody is going to say, if I take a space hotel and I want to operate it efficiently and economically above low Earth orbit, I have to add a greenhouse to this thing to grow at least some of the food. And maybe I want to investigate some ways of shielding against galactic cosmic rays beyond the magnetosphere, either using magnetic approaches or mass shielding. In a case like that, the Bigelow inflatables, the space hotels, could ultimately begin to approximate something the size of a worldship.
Image: Gerard O'Neill's space habitats posited vast environments that might eventually free themselves entirely from our Solar System and journey to the stars.
PG: We always think of worldships as countless generations away, but what you’re talking about really isn’t that far down the road.
GM: No, this is happening at a remarkable speed. And I think a lot of people are unhappy about this because they have the old model of space development in mind, that it is going to be government-directed, with benefits trickling down towards the populace. But you could just as easily have something where a wealthy individual at the top of the economic ladder funds this, in the same way that wealthy people funded the Renaissance 500 years ago.
Moving Into the Cosmos
PG: That’s a fascinating notion. So this is organic growth we’re talking about. As we move into space for whatever reason, we start building in a small way the kind of habitats that may eventually become quite large, of O’Neill size. And eventually we reach a point where people have been on one of these habitats for long enough that it becomes a preferred way of life. Is the idea then that someone says let’s just stay inside our habitat and go explore the stars?
GM: The studies that were made of worldships in the early 80s by people like Alan Bond, Tony Martin, myself, these indicated we can talk about millennial journeys, taking a couple of thousand years using either fusion pulse or high performance solar sails unfurled near the Sun. And maybe there are other approaches we can talk about, like the electric sail. Certainly once you have a population who are living out there or used to existing in deep space, a group of people who aren’t attached to the Earth, some of them at some point may just decide why not move out to Alpha Centauri, or Tau Ceti or wherever? Worldship inhabitants might become the ultimate migrants, traveling between stars and choosing not to inhabit any of the planets that they come across. Instead, they might just re-provision and move on. This is something that recalls the SF of the 70s, such as Larry Niven’s Outsiders [an alien race from his Known Space series]. The Outsiders are doing exactly that, traveling in worldships, and they consider it nearly low class to travel at a speed greater than one or two percent of the speed of light.
PG: I love that because it’s such a reversal of conventional thinking. Everyone is trying to go as fast as possible, and at the same time we all have the sense of short-term horizons. Here we’re saying, what’s your rush? And if we don’t get there in this generation, maybe we can in the next, or maybe in a hundred generations.
GM: Exactly. And that’s what they do. As I recall, the reason that terrestrials developed hyperdrive in these stories is that it’s a trade item for the Outsiders. They don’t care about things like that, but they’re trading for the things they want. Sure, hyperdrive is an interesting technique; it allows you to go fast if you want, but to us the voyage is the more important thing.
PG: I love the Niven stories of that era. Now you remind me I must go back and do some re-reading of those tales.
GM: Sure! They’re fabulous. And the more I think about it, the more significant science fiction is to science. Visionary science fiction is very, very important. People like Clarke, Asimov, Stapledon. Asimov does speculate that the early migrations from Earth are by worldships. He calls them interstellar arks.
PG: In which books?
GM: In the Foundation series, he does mention that the ruins of some of these arks are discovered around planets orbiting various stars, including one or two planets in the Alpha Centauri system, and they’re not sure where they come from. One of the speculations is that they come from Sol originally, 50,000 years ago. But the records have been lost.
The Worldship and the Sail
PG: Greg, although you are not going to London for the worldship conference, I know a paper of yours will be presented there on the question of using a sail for propusion. Tell us more about that.
GM: What has happened with the sail is that we know that solar sails are the only propulsion system for interstellar travel that people have suggested to date that can be used for acceleration, deceleration and cosmic ray shielding enroute. Because you simply wind it around the habitat. So it’s a tri-use device, which none of the others methods have. And what I do is I review a lot of the literature including acceleration and deceleration and I talk about the fact that right now the most investigated sail material is beryllium. People at NASA hate that.
Image: John Desmond Bernal, a British physicist and crystallographer whose The World, The Flesh & The Devil (1929) investigated a human presence in worldships and discussed the possibilities of solar sailing long before it became fodder for scientific papers.
Les Johnson [NASA MSFC] was at a conference in Aosta, I forget if that’s the one you were at, and when I described the work of a beryllium sail, he did a wonderful imitation of Indiana Jones and said, “Oh no, why did it have to be beryllium?” Because he’s making a very good point. If NASA wishes to build an Oort Cloud explorer which is going to be a small scale 2000 year ark — and in fifty or sixty years they could build this to demonstrate a prototype interstellar spacecraft and also to do exploration of the Oort Cloud — right now beryllium is their only candidate for the sail, but beryllium is also very toxic. Les was saying if we do this, we’re going to have to deal with huge losses and tremendous safety issues. I understood his point, but technology is changing very rapidly.
There are things like carbon nanotubes and more recently graphene. These are interesting because they could have thickness measured in nanometers. Maybe a couple of molecules thick. They would have a finite either reflectivity or absorptivity, which means even though they are extremely low in mass, they are very strong. They’re going to be pushed by photons. So you could certainly imagine lowering the interstellar transit time with the sail to something like a millennium, maybe even lower than that. I don’t know. I would hesitate to say that we’ve discovered everything.
PG: I actually remember Les saying that about beryllium two years ago in Aosta. But you’re saying that these possibilities are going to be significantly thinner than anything we might do with beryllium?
GM: I think they’ll be both thinner and stronger than what we’re doing with beryllium, and they may not be toxic to work with. Right now they are amazingly expensive. If you were going to come up with enough graphene to cover a postage stamp, it would cost something like a hundred million dollars. So to build a real starship would bankrupt the planet. Even if we paid it out over a century. So the graphene price has to come down by many orders of magnitude.
One person at the Aosta congress did suggest that this isn’t impossible because this is what happened with aluminum. Aluminum when it first became recognized as a possibly significant commercial metal, probably a century and a half ago, was remarkably expensive. But a number of commercial processes were developed and the price began to drop dramatically. And as it dropped, people found more and more applications, driving the price down still further.
PG: What sort of mission configuration would you foresee? We can talk about a close solar pass, but our colonists are not in any great rush anyway, are they?
GM: They’re not. If you are using graphene, you might even be able to start with something like Earth orbit to get there in a thousand years. Because it’s very, very thin. A lot depends upon how its reflectivity or absorptivity varies with temperature. We really don’t know much about this material at this point to any great depth. I’m going to be talking about this also in Orlando, and presenting some of the numbers one of the guys presented at Aosta. But it’s not something you can get your hand around at this point. It’s still a brand new material that’s extremely difficult to work with. It’s very expensive, and there are only a handful of labs on the planet that can fabricate the stuff. So right now it’s a scientific material but not yet an engineering material.
Life Within the Colossus
But I do think if you’re going to extrapolate how to engineer a worldship, you would think about something that is a small version of an O’Neill colony. It maybe has the dimensions of a small skyscraper, maybe a hundred meters high, twenty meters across. That’s the payload. The payload might mass something like 107 kilograms if it’s using a 2000 year beryllium sail, an inflatable sail, maybe the sail size is 600-700 kilometers.
PG: Huge sociological issues come into play when we’re talking about millennial voyages.
GM: Our crew would have to deal with interesting sociological matters. How do we become a society that stays intact for that long? And it was interesting that Arthur C. Clarke was not an optimist about the sociology. He was an optimist about the technology. In one of the Rama novels [in the series that began with Rendezvous with Rama, 1972], Rama was an alien worldship that comes to the solar system and aliens invite the terrestrials to fly a ship out and colonize it and live there with some of the aliens. Ultimately a few thousand terrestrials take advantage of this, and they have to decide how to live on this worldship. They decide to have a society with a lot of sports events, so they build stadiums for these. What happens is one of the major team players says I can take this place over. And he develops a cadre of fellows to work with him who enslave or massacre the other males and the various women become sex slaves.
He develops a fascist state with him on top. And what happens is one of the women revolts and she is able to get in contact with the worldship intelligence, which is the supreme intelligence of the universe, so she has a good deal of help, and because of this there is a very successful revolution. But OK. In any event, what Clarke is presenting there is pessimism about sociology and so was Heinlein in ‘Universe’/‘Common Sense’ in the early 1940s. He has a worldship going between Earth and Centauri and the society falls apart. So basically all the people assume this is their universe. These two stories became the novel Orphans of the Sky, published as such in 1963.
It’s a brilliant story and of course the protagonists break in somehow to the holy of holies, the control room, they see what the stars are, they learn about the universe and they just happen to be passing through a solar system which is probably the Centauri system and there happens to be a livable planet. Somehow the shuttlecraft is operable by non-experts and they are able to elicit a landing. OK, Heinlein was playing the odds to have a happy ending to the thing, but the sociology is going to be a major factor because we haven’t had small human communities isolated for that long. There have been a couple of experiments and their results aren’t that good.
One of the experiments is the Vikings in Vinland. And when you look at that, the Vikings come and settle a small colony in Vinland [the account is told in the Saga of the Greenlanders]. One of the women is Freydis, the daughter of Erik the Red, who decides it’s too cold in the winter. She wants to be warmer, and why must she have only one male to snuggle up with? So she slaughters all her sisters and she has all the men now. This is in a small colony and they have nothing to do with the surrounding people, who they call Skraelings, the native Americans. So that’s an example maybe of a space colony gone wrong and becoming a tragedy.
Image: Robert Heinlein was one of a number of science fiction writers of his time who investigated the potential — and the problems — of worldships. Credit: The Heinlein Trust.
PG: On the other hand, I suppose one potential cause for optimism would be that a large enough worldship is going to have quite a large population, so perhaps that kind of diversity might play to survival. But I think the larger point you make is exactly in tune with the upcoming starship conference, mainly that while we usually think of interstellar ideas in terms of the propulsion that would get a probe there, the field actually demands a multidisciplinary approach.
GM: Very true. You make a good point about having a large population and I think O’Neill speculates that for a space habitat to be self-sufficient, it needs a population of something approaching a hundred thousand. Certainly tens of thousands of people. Then you have to say, what are they all going to do? If you have a large population like this, what will they do between stars? You have to design a ship in such a way that maybe the ship is never completely finished. Maybe the ecology always needs adjustment for it to work. Or maybe you have a second ship launched with materials to be mined as needed. Going out to the second ship and mining that becomes one of the periodical heroic episodes for this enclosed culture. Because look at the fact that we do seem to need heroes, in war or hopefully more frequently in sports. Look at the number of sports the industrialized and developed world practices today, and that’s to keep sane. That is largely to take the people who would be actual warriors and give them a role in society so they don’t have to go around other countries hacking off peoples’ heads.
A Multidisciplinary Study
PG: So all these things point us in the direction of the need to assess sociology, philosophy, history, to look at how humans have done in other settings when they’re in remote places.
GM: Yes. I would love to know the early history of the Minoan colonies in places like what is now Gaza. Or when the Minoan/Mycenaean peoples colonized Miletus in Asia Minor. Miletus becomes the parent for Russia, for many of the eastern European countries, because many of the people from there starting in about 1000 BC begin to build colony cities around the Black Sea area. I would love to know how many of these succeeded, how many failed, what the interaction was. Did they war with each other, did they war with the indigenous populations? I’m likewise fascinated with the early story of the Etruscans. They were obviously strongly influenced by the Minoan/Mycenaean civilization, but how did they do this? Were they a direct colony? We’ll probably never know. Or were they indigenous people who traded to try to build their own cities?
PG: You mentioned the possibility of having a second ship that might have resources the first could exploit. Is there an argument to be made that human nature says in any case a second ship is a good idea because you need to have a neighbor, a potential other, out there with you?
GM: It’s a possibility, that you might send instead of one ship a small fleet, particularly if you’re using something like a solar sail or a photon sail or maybe even an electric sail — you don’t have to pay for the propulsion. And in either case like this, conceivably, you could send as many colonies or habitats as wanted to go. That may offer something like this, because they could trade with each other, maybe they could have political or athletic contests with each other, maybe even there could be some form of highly ritualized warfare. I know that warfare among some of the native American population was initially very ritualized in just such a fashion. So we might be able to find all types of possible models in history and pre-history to go with.
PG: This discussion harkens back to that wonderful 1983 conference ‘Interstellar Migration and the Human Experience,’ where you did have a very multidisciplinary group coming together to look at this kind of question, relating the topic to events like the settlement of the Pacific islands.
GM: Yes, that’s exactly what Ben Finney did. Unfortunately, I was not at that conference [held at Los Alamos in 1983, proceedings available], and always wish I had been. I’ve never met Ben Finney and would like to. I’m hoping he’s at the 100 Year Starship conference.
PG: Same here. I’m looking forward to seeing you at that conference, Greg, and want to thank you for your time this evening. As always, it has been a pleasure to talk to you.
Addendum: Kelvin Long sends via his smartphone this shot of the lunching worldship conference crew at the BIS headquarters where, as I post this (1600 UTC), the event should be just wrapping up.