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Musings on Impartiality

Marc Millis, Tau Zero’s founding architect, drawing on his experience with NASA’s Breakthrough Propulsion Physics project and the years of research since, offers us some ideas about impartiality and how scientists can hope to attain it. It’s human nature to want our particular theories to succeed, but when they collide with reality, the lessons learned can open up interesting alternatives, as Marc explains in relation to interstellar worldships and the possibilities of exotic propulsion.

by Marc G. Millis

The best researchers I know seem to be able to maintain their impartiality when reaching new conclusions. The more common behavior is that people get an idea stuck in their head and then try and prove themselves correct. I just learned that there is a term for this more common behavior: “Polemical.” Embedded in the word is the notion that controversial argument can turn aggressive, an inevitable result when people are defending what they consider their turf.

I mention this in the context of getting trustworthy results, and then acting on those reliable findings rather than just charging ahead based on unverified preconceived notions. If the overall intent is to make the best decisions for the future – then decisions rooted in reliable findings, rather than expectations, will be more in tune with reality. They will be better decisions.

The topic of interstellar flight affords opportunities for easier objectivity as well as the opposite – pitfalls where one can lose objectivity. Because interstellar flight is almost certainly farther in the future than the next Moon and Mars missions, it is easier to apply impartiality. The huge payoffs of interstellar flight (finding new human homesteads and new life) are far enough away that there is no need to sell a particular pet technology today or skew the results toward near-term promises.

That said, I surprised myself when my own assessments gave results different than my expectations. Case in point – estimating how far in the future the first interstellar missions are, based on energy (energy is the most fundamental currency of motion). Those findings and a refined sequel (to appear soon in the Journal of the British Interplanetary Society) indicate that the first interstellar missions might be 2-centuries away, albeit with huge uncertainty bands.[ref]Millis, Marc. (2010) First Interstellar Missions, Considering Energy and Incessant Obsolescence, JBIS Vol 63 (accepted, pending publication).[/ref] The first Centauri Dreams post on those findings met with ‘energetic’ reaction, where many seemed disappointed that the prospects seemed so far in the future. Before I ran the numbers, I suspected that it would be much sooner too. The first calculations were done around 1996, and those results made me rethink what ‘next-steps’ were really required.

Rather than proceed with my prior notion, I had to stop and rethink things. The data said something unexpected. I knew I had conceived the methods to be impartial and fed the assessments with unbiased data, so the findings would be similarly unbiased. They were what they were. So, should I redo the analysis until I got the answer I wanted, or accept the results for what they were and then re-adjust my expectations? I decided to expose those results to other reviews, to check for errors and such, and then to accept the findings as they were.

Before that point, I thought the next step would be to use more detailed energy assessments to help pick the best interstellar propulsion options, but with two centuries of time to plan ahead, and many options whose numbers were still debatable, I realized that we need to abandon the idea of trying to pick the ONE best interstellar solution. Instead we need to focus on getting reliable data on the wide span of ideas (no salesmanship) – and to investigate the most critical ‘next-steps’ on as many of them as possible.

And this long lead time provides the topic of interstellar flight with the opportunity for more objectivity – the opportunity to take our time to reach sound decisions – to provide more trustworthy progress.

Colony Ships and Spaceship Earth

The other result that I was not expecting was that colony ships might be easier to launch than small, fast probes – at least in terms of energy. My prior expectations were that colony ships would need to be so immense and complicated that they would take longer to develop than a fast probe to Alpha Centauri. The energy study showed otherwise. Kinetic energy is linear in mass, and goes as the square of speed. That means if the ship is twice as massive, it requires twice as much energy, but if it goes twice as fast, it requires FOUR times the energy. Colony ships do not need to go fast. They only need to drift, carrying a segment of humanity. Up to that point, I thought colony ships would be a sequel, not a prequel to small, ultra-fast probes. Sometimes you just have to run the numbers.

Then it occurred to me, while I was drafting my first TEDx talk, that the notion of such slower interstellar world ships also provides a more impartial venue to discuss critical human survival questions. Colony ships allow us to consider these questions with NO dependence on conventions or biases. If designing a society from scratch, one is free to start anew to fit the facts as they are discovered. On Earth, however, when dealing with questions of population size, environmental stability, amount of territory per person, and governance model, the debates are typically won by cultural edict (e.g. no birth control) or warfare (quest for territory or power). So, after all that, I realized that colony ships merited far more attention than I originally gave them, and hence, we will need to track down suitable pioneers to cover those issues too as part of Tau Zero.

Unbiased Physics

When it comes to one of my pet topics – propulsion physics and the quest for space drives – I ran into another facet of impartiality. I found that many physicists do not like to work on problems with potential applications since the application ‘taints the purity’ of the research. Instead they want to be driven by curiosity alone. In other words, they do not want to be biased. In the quest for propulsion physics, where I really hope a space drive method can be found, I have an ingoing bias. I want the results to turn out a certain way. This creates a conflict of interest in how I might view – or skew – the results. To make genuine discoveries, however, I must discipline myself to avoid imposing such biases. Although I can let my wishful musings help me pose the key questions, to get real progress I must also let the findings – unbiased findings – answer those questions. I must accept the results as they unfold.

Take the case of black holes in contrast to traversable wormholes or even warp drives. Studying black holes has revealed insights about spacetime warping, presumably without bias since no desired result is sought. But if one studies the very same physics in the context of faster-than-light wormholes or warp drives, one might get biased results because of wanting such devices to be feasible. Fortunately, much research published on these topics has maintained the rigor to avoid the taint of such biases. Insights into spacetime physics are also being learned by pondering warp drives and wormholes. These questions are even presented as homework problems in textbooks (e.g. Hartle (2003) Gravity: An Introduction to Einstein’s General Relativity).

The irony is that even the curiosity-driven research has implicit biases – that natural sense of ownership that a person has for their research ideas. There is an urge – even in this case – to have the findings prove the author’s pre-conceived point. This is just a human norm. High-quality physicists can discipline themselves to separate out this bias. In contrast, I’ve also seen physicists discuss their ideas with the same possessiveness as kids with toys on a playground. Regardless of our motivation in searching for new knowledge, we must maintain vigilance to avoid imposing our own biases on the findings, even the implicit bias of self.


Comments on this entry are closed.

  • henk June 24, 2011, 9:31

    I agree with you. If you look at star trek that you can go to the other end of the galaxy in a blink of a eye. Who does not want to do something like that. It is a dream that we all hope that one day that can be true. But we need to be sientific about those things and for now we can not create such thing. How can you control space and time to your will that you can turn it on and of just like by a flash light. We need to learn about those things first. And if it is inpossible. We will probably never stop trying. But maybe in 500 years it is just as normal as traveling with a train

    I have found something about scientists trying to predict the future — when we will find a earth mass planet in the habitable zone:


  • Paul Titze June 24, 2011, 11:22

    Marc Millis wrote:

    “I found that many physicists do not like to work on problems with potential applications since the application ‘taints the purity’ of the research. Instead they want to be driven by curiosity alone.”

    As for ‘purity of research’, I wonder sometimes if some physicists who delve into some some theoretical topics are doing Science at all. Some spend many years on topics which make no new testable predictions and cannot be verified by experiment (very convenient). String theory, multiverse theories, extra dimensions to name a few (all incorrect). I’d like to see more physicists concentrate on Propulsion Physics which can lead to more useful results and potentially bring important benefits towards interstellar travel. Even if no breakthroughs are found, the results learnt along way can be beneficial because deadends can be ruled out, that’s how progress is made.

    Cheers, Paul.

  • Alex Tolley June 24, 2011, 11:39

    Is the future really some sort of unbiased outcome, or instead the result of biased events? A desired future will influence the actual future.

    A new space propulsion method[s] will arrive only if the physics and technology allow it. If it had military applications, the military might fund the research, especially if there is a perceived competitive situation, and drive development.

    A future several hundred years out is so uncertain that any extrapolations of politics, science, economics is impossible.

  • Norm Davison June 24, 2011, 11:54

    I think this is very good post. To begin first work on a step as large as interstellar travel, one has to be able to stand back and look at things objectively. This is extraordinarily difficult, even as regards the physics. Realistically, as far as it is possible to see *at the moment*, for interstellar flight, we must rely on mundane, “boring”, “old” physics, i.e. no warp drives, no space drives, just plodding <10%c flight, at best. Many (most of us?)would like to see a revolutionary new approach, but when you get down to serious planning, that's not objective.
    I was disappointed to see in the 100 Year Starship project that there will be discussion on warp drives, wormholes etc. I had hoped that this project would look into what might actually be feasible. I don't think we are anywhere even close to implementing ideas that involve manipulating space itself. I hope I'm wrong; it is conceivable that "space drives" etc will become possible in century or two, but for now, they are not even dreams. Keep up the curiosity driven research, but don't waste real planning time, i.e. time directed towards the feasible, on anything exotic until it becomes unexotic.
    Now, can we be objective – really? How many people (or governments) are willing to look at the politically incorrect? If you won't/can't look at nuclear explosive propulsion (with specially designed bombs) you can't claim an objetive approach until it is demonstrated, on the basis of Physics, not politics, to be an unworkable approach. How many people could even begin to accept the results of a careful, objective study that showed western style democracy to be inferior to a Chinese style of government for a colony ship? I've never heard of any methodology that allows a truly objective study of governance systems; perhaps developing such a methodology is one of the requirements for designing a colony ship.
    I suspect that no one country can design a starship. In any one culture or political system, there will be too many "unthinkables" that make objectivity impossible.
    How then to proceed. I think the first step is to identify blinders and blinkers that inhibit our objectivity. This will involve a lot of critical examination of religious, philosophical and political biases, and may be impossible or close to impossible. If questioning our deepest beliefs turns out to be a wrenching experience leading to impasses, then we will have to ask whether or not we are ready to undertake interstellar flight.

  • kurt9 June 24, 2011, 12:41

    Without any physics propulsion breakthroughs, 2 centuries is about right for the first interstellar migrations. Before we can go to the stars, first we have to learn how to live in space for extended periods of time. This is where the old O’neill/L5 scenario comes in. Each space colony is an independent city-state, kind of like space-based versions of Hong Kong and Singapore. There are a lot of resources in our solar system in the form of small objects. The number of NEO’s is comparable to the estimated main belt population from O’neill’s time. The main belt population is 10 times greater than estimated then. The Jupiter Trojans are comparable to the main belt and the Neptune Trojans are 3-10 times greater. Then there’s the Kuiper belt. Learn to build and sustain space colonies and you have lots of room for growth and opportunity. Besides, if we have to crawl our way to the stars at sub-light, it will be done with a mobile O’neill anyways.

    If we get breakthrough propulsion (FTL, wormhole, etc.), we could go to the stars in the next 20-40 years. Serendipity indeed!

  • Interstellar Bill June 24, 2011, 15:10

    Kurt9 makes precisely the point we must not forget:
    Interstellar Flight will neverbe done by any Earth-based country,
    because there will never be enough money for it.
    Just consider that just the Icarus fuel load could provide all of Earth’s electricity for a year, something like $5 trillion today.
    So you’re looking at total price tag above $10 trillion,
    just for a ‘fast’ unmanned probe,
    about 50,000 times that of today’s spacecraft.
    Its scientfic return, however, would only be a modest multiple of today’s missions, certainly not 50,000 times, especially considering how much cheaper a large space telescope is, or even a fleet of them.
    Thus we must picture a civilization about 50,000 times bigger than ours,
    obviously only possible with a huge interplanetary population.
    After all, a ‘generation ship’ is nothing but a space-habitat on the move.
    In conclusion, any study of interstellar flight must necessarily begin with a 200-year projection of interplanetary population growth. As long as we’re all on one planet we’ll never be able to afford the stars, espcially since it is extremely unlikely that there are any habitable planets within even a few hundred light years, impossibly far for any early flights.
    A space-faring civilization, however, need only get to Epsilon Eridani to find lots of asteroidal raw material, so habitable planets won’t matter anyway.

  • Mark Presco June 24, 2011, 15:22

    I believe the future of the majority of the human race will be in colony ships. Firstly, they will be an integral part of the Dyson swarm that hopefully will fill the Solar System as we harness the total energy of the sun. While each ship may be limited in space the swarm is not.

    I also believe they will be zero-g since that is much cheaper than artificial gravity structures.

    Only after these habitats have been proven reliable should we send them to neighboring stars.

    The priority is to first establish an off-world population.

  • Astronist June 24, 2011, 18:03

    I agree absolutely with Kurt9, Interstellar Bill and Mark Presco. I think we proponents of interstellar flight would do ourselves an enormous favour by talking less about propulsion physics and more about getting this simple message across to the public: as population and economic growth on Earth ramp down over the next century, so in space they must ramp up. We need permanent and (for a thousand years or two) exponentially growing extraterrestrial populations in order to preserve the paradigm of growth and progress which is the fundamental concept of our civilisation, and in this sense the survival of democratic civilisation depends on space growth. Earth as the metropolis of the Solar System can preserve economic and political freedom; Earth as a zero-growth tyranny cannot.

    Kurt9, would you happen to have references in the literature to those estimates of the asteroidal mass in the Jupiter and Neptune trojan swarms, please? I could use them in a paper I’m writing.

    Oxford, UK

  • Athena Andreadis June 24, 2011, 20:25

    Star travels by FTL, wormholes and warp drives are pipe dreams for humans, since we are inherently fragile plus our technology window is threatening to close (that is: we won’t go much further technologically before we run out of raw resources). Colony ships attempting to reproduce self-sufficient ecosystems have been the sole feasible concept from day 1 and will remain so to the bitter (or hopeful) end.

  • Kenneth Harmon June 25, 2011, 0:34

    Sadly, Athena has hit upon a core issue. Simply put, we may not have the luxury of a couple of hundred years before initiating Interstellar Travel. This is especially due to some of the limitations Athena mentioned as well as other fundamental structural problems of our current Civilization. At best, and if we are very, very lucky we may have until the start of the 22nd Century before we hit a temporary period of decline or at least a plateau in our progress. That is of course unless Ray Kurzweil turns out to be correct.. Consequently, unless we get lucky in terms of propulsion this probably means the Colony Ship option to Alpha Centauri is the best we will be able to do for a long time to come, although it may be a Colony ship that is goes 10%+ the speed of light.

    One of the things that Marc Millis may want to do is explore and challenge the underlying operating assumptions of his Energy calculations. Although he may be biasing the research there is nothing wrong with exploring what could really change things and when. In essence, look for potential game-changers for the energy calculations

    For example, perhaps there will be a clear and present need by the end of the 21st Century to conduct Interstellar Travel as things become more difficult on Earth and even throughout the rest of the Solar System. Therefore, the “Energy Budget” may rise as the need increases so todays ratios may no longer apply.

    One other way to look at the problem may be to say that if we find something of interest around Alpha Centauri then Interstellar travel may happen allot sooner then currently projetecd given known physics and technology. This is because it will be more “doable” as a one off event if clear need emerges. If we find nothing of interest around Alpha Centauri then we are probably down to some sort of new physics if we have any hope for Interstellar Travel before our current Civilization is overtaken by other events, and we either plateau or start to decline at least on a temporary basis. The entire 22nd Century is starting to look like a very tough time indeed for Human Civilization.

  • Joy June 25, 2011, 1:57

    Thank You Marc!
    (and thank you Athena)

    I recall the optimism of the 1960s when energy production was growing at 7% per annum and world population at 3% per annum. Life was getting materially “richer” everywhere by about 4% per annum as the per capita energy available was increasing exponentially at that rate. (In fact, in East Germany, prices were frozen, but wages rose 4% per year, not a coincidence.) It was human nature to see the parabolic increase in energy per capita as both an inevitable product of “technology” and optimistically imagine it to be a hyperbolic function. Even now people dream about a technological “singularity” over a coal powered internet!

    Yet, the fusion plants, safe and affordable thorium fission plants, and space solar power stations wished for in the 1970s have failed to appear. Consequently world energy production per capita had been essentially flat 1979-2008, and now may have started a long decline. Median and mean living standards are likely to slowly decline for several decades. While that does not mean that continuing advances in spaceflight are impossible, it does limit the options available.

    For example, history is full of examples of societies with extreme inequality, including slavery. There is no reason that even brilliant PhD engineers need participate in a consumer economy. So energy surpluses for elite agendas can be preserved by enforcing austerity on the workforce. (Constant electronic surveillance, a centrally controlled electronic financial system, and a planetary police state would be needed to achieve this, but construction of these systems is well underway.) Healthcare for the masses is a luxury, as are retirement, personal vehicles, private housing, meat, and consumer goods. The lavish support of non-productive and sociopathic individuals is also a luxury of 20th century affluence unlikely to be maintained, so population can be reduced. All of these things can be done for energy and raw materials savings. Still, I consider high energy (such as 10^21 joule) space missions to be off the table … indefinitely.

    Perhaps the largest problem is that the world’s financial and power elites have shown no interest in spaceflight. The likes of Dominique Strauss Kahn and Henry Kissinger have been pursuing other interests … Yet people of this ruling class are the “deciders” of our civilization.

    The solar departure speed of spacecraft presently in flight is circa 0.00005 c or 20,000 years to travel one LY. A leap of a twenty-fold velocity improvement to slow interstellar vehicles traveling at circa 0.001 c can be imagined with near term (this century) technologies: VASIMR, or “Dual-Stage 4-Grid” (DS4G) ion thrusters, or more speculatively, beryllium hollow-body solar sails. Faster propulsion systems range from the extremely speculative to flights of fantasy. It is sobering to realize that there is no guarantee that we will ever be able to travel to even the Alpha Centauri system in less than circa 4000 years. On the other hand, even a 20,000 ton crewed vehicle would have a kinetic energy of just 10^18 joules (or one quad) in flight. A 1000 megawatt commercial fission plant operating continuously will product this quantity of energy over 33 years. Surplus energy of that order of magnitude could – at least in theory – be made available now. The difficulties of orbiting, assembling and operating commercial sized fission plants in space are yet to be addressed.

    As Athena has alluded, our civilization is already constrained by resource limits, and likely to face declining material and energy availability. This reverses the old optimistic assumptions. Conventional wisdom has been that slow interstellar missions are pointless, as progress would cause them to be overtaken by faster missions launched in an inevitably advanced future. Instead, we must consider the possibility that we should launch a slow mission if we can, because even those might be impossible in an impoverished future.

    The two main options are “spore” missions, which carry dormant life on an AI platform versus generation ships. Neither option has yet been proven feasible.

    The least massive vehicle (cheapest) option would be to send dormant life. We already have the technology to freeze human embryos indefinitely. Unfortunately, we do not yet have artificial wombs, or an AI nanny to raise the babies grown on arrival. Funding of development of these technologies would be a wise investment.

    Likewise, the feasibility of generation ships hasn’t even begun to be tested. We have not yet demonstrated a closed ecology, even on Earth. Also, to my knowledge, no one has even attempted to raise several generations of mammals in space. No one of influence since Van Braun and O’Neill has even considered the creation of rotating space habitats with artificial gravity. That those essential and simple experiments are not even on the agenda is deep evidence that our civilization is not seriously interested in spaceflight.

  • Tobias Holbrook June 25, 2011, 11:07

    This issue seems to come up every time there’s a discussion about interstellar flight – I’ve said it before, and I’ll say it again; energy budget does not matter much if you’re using fusion starships. I repeat, energy budget does not matter much with fusion starships. It’s the raw price of the fuel which does.

    How many kilowatts do people need to live a life of luxury? 1000? If so, then any energy left over after we’ve provided for the 10+ billion in the solar system will no doubt go on mega engineering projects. The energy budget is essentially unlimited, especially if you live near the fuel source.

    This is supposing fusion, of course. Solar carries it’s own cost, but if we can somehow grow solar panels cheaply and in large numbers, that may not be an issue.

  • bigdan201 June 25, 2011, 12:30

    A natural part of the thought process is creating beliefs. It would be unnecessarily arduous to analyze and consider everything, so even a rational mind creates belief systems for understanding the world. There’s nothing wrong with that. However, this becomes an issue when researching, theorizing and looking for answers. The tendency is to form beliefs and build on them – so once you have a strong mental structure for how a galaxy formed, or how some phenomena occurs, you won’t want to abandon it. The instinct is to defend it, until it becomes abundantly clear that the model needs to be revised or thrown out.

    While this is an obstacle to impartial research, it’s not that bad by itself. After all, it’s important to have a solid foundation in established laws and theories, so that you don’t go off the deep end into pseudo-science. But it can be an obstacle, especially when one’s views get entrenched.

    The worst is when a scientist puts their ego into a theory: then, debate turns into a personal attack, and things can get messy.

  • Astronist June 25, 2011, 19:19

    Athena, Kenneth and Joy: concerning resource limits.

    The plain facts are that the power budget of our current global civilisation is around 15 TW. The power generated by the Sun is 380 trillion TW. There is room for growth. Joy talks of a starship which consumes 10^21 J: the Sun generates 380,000 times as much energy every second, as it has done for billions of years in the past and is guaranteed to do for billions of years to come. There is no shortage of available energy, even if we don’t master controlled fusion.

    Certainly, Peter Glaser’s and Gerard O’Neill’s vision of solar power satellites has not yet come to fruition. That tells us nothing. Often when a new technology is envisaged, it is not yet practical, but must await an enabling technology. Von Braun pointed out that the enabling technology for easy access to Antarctica was the aeroplane; other examples would be powered flight, which had to wait for the invention of the internal combustion engine, and the computer, which had to await electronics. Economic solar power satellites look to be dependent upon low-cost access to orbit, which is on the way, slowly. Meanwhile there is no shortage of fossil-fuel and nuclear fission energy to keep us going on Earth for a while longer, and no shortage of countries which have few qualms about using them.

    As I said above, the key point to stress is that we need to see the ramping-down of growth on Earth at the same time as ramping it up in space. The resources of space allow a population to be supported which is at least one million times greater than any possible on Earth alone, as John S. Lewis and others have pointed out. Maybe this won’t happen. None of us can be certain what the future will hold. In that case, there’ll be no starships. But it is a possible future, and it is our job to let people know that it is a possible future.

    True, world leaders have other priorities. I do not see that this is relevant. Expansion of a civilisation into space is an evolutionary process, i.e. not one planned or directed by some godlike intelligent designer. It happens (or does not, as the case may be) through a myriad of choices taken for more immediate reasons. This is how life emerged from the sea to colonise the land, and it is how our ancestors grew large brains. Certainly at this stage of the process we can start to nudge it forward a little bit with rational planning and inspiration and forethought, so space entrepreneurs and engineers get inspired by science and by science fiction, and pursue the vision of expansion into space. But I think we need to avoid the socialist vision in which nobody can do anything until the authorities duly appointed by the state give them their marching orders.

    Please be patient! This is a momentous change. It’s not going to happen in a few decades. If it takes us a thousand years to get self-sustaining populations living in rotating space colonies, that’ll still only be a blink of the eye on the cosmic timescale, and less than one per cent of the age of our species so far (taken as 200,000 years). Think of the ups and downs of history: progress is never linear, but always haphazard and erratic. Think of the devastating impact made by the fall of Rome: the future we are envisaging will be about as different from our current society than ours is different from the ancient world.

    Providing that we avoid absolute disaster (nuclear conflagration, a supervolcano episode, etc.), at some point in the next few decades, when the circumstances are right, there’ll be an explosion of activity in space, analogous to the global explosion of exploration, trade and (yes) colonisation from about 1500 onwards. That’s my prediction for the next millennium or so.

    Oxford, UK

  • jkittlejr June 25, 2011, 23:58

    First , congratulations to Marc for a truly well thought-out and balanced article. Second I was also impressed by the quality of the responses.
    I would like to make just three points .
    1) Advocacy of an idea is a big part of real science- you need a lot of sustained effort to get a persuasive grant written, or a company started, let alone the drive to do the work. While it is important to be objective, without some belief in what you are doing( i.e risk taking), then little is accomplished. I think of the Human genome project. when it was first started, the technology was far short of what was needed ( a fact that could be proven in a back of the envelop calculation)- and yet we started on sequencing Bacteria, which could be done in principle, though 1,000 fold less difficult than the human genome. Twenty years later, not only do we have the genome of humans and >1,000 other organisms, it is now cheaper to get a genome sequenced that to buy a compact car!
    The trick is to advocate, learn and then BE OBJECTIVE about the results.
    2) The second point also was demonstrated in the Human genome project, is that you need to have lots of alternative technologies started and then weeded out as the process moves forward. You can also add new thinking along the way. This requires sustained effort as well as leadership that is both imaginative and practical. Some competition ( within bounds) is also essential ( think Venter vis Collins, Celera vs NIH, ABI 3730 sequencers vs Megabase) and yet there was tremendous cooperation as well. The final “first drafts” had data from a dozen research centers and required thousands of researcher working in a dozen different disciples
    3) Finally I ask a question that may be pondered now:
    If we limit ourselves to known physics for energy and solar sails, ion or particle drives for propulsion, and use live (not sleeping nor immortal) humans for crew , WHERE IN THE SOLAR SYSTEM IS THE BEST PLACE TO LAUNCH FROM?
    let me list some choices, you can add your own:
    Earth , Luna, Mars, Ceres, Callisto, Triton, Pluto, Eris , Mercury
    You can see right away some of the criteria I used by a common factor in my choices..

  • Joy June 26, 2011, 1:20

    I understand where you are coming from as I held all the same beliefs when I was younger. The key concept that is missing is the idea of energy returned on energy invested or EROEI, a thermodynamic concept independent of politics, sociology, or economics. In evolutionary terms, if you prefer, an animal deprived of high quality food sources that requires 1500 joules to digest a low quality, high bulk 1000 joule meal is doomed to starve and go extinct.

    Most of the fossil fuels in the ground will remain there forever as the energy cost of extracting them would exceed the energy gained from burning them.

    The EROEI of both coal and oil has been falling greatly over recent decades. The days of picking anthracite off the ground are gone as are the days of striking a light sweet crude gusher with a 50 metre bore hole.

    The EROEI of fission is highly controversial. Certainly the fuel contains more energy than expended in mining and refining it, but that is only part of the story. Even absent any sort of taxation and regulation, there is a lot of embedded energy in the plant itself (it costs energy to make steel, concrete) and its construction, operation, and eventual decommissioning. Not to mention the energy required to construct and maintain a permanent waste storage facility – still not in existence. I believe there is a net energy gain with nuclear power, but far less than first imagined. Probably more like 5:1 rather than the 100:1 gains seen with early oil wells. Still, that is better than the 3:1 EROEI of synthetic oil made from mined tar sands, fresh water, and natural gas. Which is why China will build more fission plants, not because they are so great, but as the best of bad options.

    Wind power has a positive EROEI, probably better than 10:1 at a good site, but sites are limited. Space solar power of course has unlimited potential (and probably always will) as it is dependent on cheap access to space or CATS, which seems more remote and unlikely now than when Von Braun wrote for Colliers in the early 1950s. I was at the DC-X flight tests in 1995, and things have only gone backwards since then.

    As for fusion … the only existing type is the thermonuclear bomb, which as Dyson suggested might provide a good type of pulse propulsion. But seriously, I am not even sure H Bombs have a greatly positive EROEI. (Dyson only suggested using the stockpile already in existence and paid for.) Accounting for the entire cost of the establishment which produced them is rather opaque. Certainly the US spent unknown trillions (10^12) of USD producing them. Start with all the infrastructure of a fission plant, refine the plutonium securely, build the device, add fusion booster … The standing army of (circa 100,000?) engineers, technicians, and security personnel involved in their production burned a lot of petrol just driving to work. Did all of this energy cost add up to more than the energy released in a 150 kt (6 x 10^14 joules) fusion burst? Yes, if all the workers and all of the facilities involved burned more than 100,000 barrels of oil equivalent while constructing an H bomb, a sure thing. The very high yield fusion devices with 50 mt yield might be positive in the EROEI balance, but are they suitable for propulsion?

    As for other speculative types of controlled fusion … maybe someday a tokamak will have a self sustaining reaction. But the EROEI will never be positive. Meaning, you would never make enough energy from the plant to construct (fund) another one. As for spaceflight with a tokamak … only if you have a James Blish spindizzy to get it off the ground along with the city needed to support it. And the NIF is just a bad joke, at least the myth of viable ICF has been Busted!

  • Joy June 26, 2011, 5:09

    Back to the original question of generation ship crew size and structure Marc posed.

    My answer is pretty simple. A generation ship would be like no band of humans that has ever existed. Genetic diversity is unimportant as there is no practical limit to the diversity of sperm and embryos that can be carried in cold storage. On arrival at destination, whatever sort of people you desire can be birthed. In flight, you want the dull changeless social dynamics of a small beehive. A biological monarchy where everyone is kindred.

    Ideally, there should be three females in each generation, the queen and her two younger sisters. Only the queen reproduces, using frozen X sperm. The eldest of her three daughters becomes queen for the next generation, and so on. If a queen dies prematurely, before having three daughters, her next eldest sister becomes queen. Simple. Everyone is family, everyone has a defined role. If 4 generations are alive at once, you could have up to 12 living crew, a manageable number. The grandmother generation rules, headed by the queen’s mother. If there is a great grandmother generation, they are retired.

    The crew would have to be genetically screened for disease within technological limitations. Cancer resistance (as much as possible) should be sought out. If genetic markers for Alzheimer’s can be found, they should be excluded. Also the centenarian mutation for growth hormone receptor resistance would be most desirable. That would not only increase crew longevity, but lead to smaller body size and lower food and oxygen consumption. Good pelvic structure for childbearing is essential, you want to have non surgical deliveries in interstellar space with a shorthanded crew.

    General intelligence is good, but only to a point. Even if AI is not available, expert computer systems programed with learning algorithms should ease any intellectual burden on the crew.

    More important is to have screened out genetic tendencies toward novelty seeking, risk taking, addictive personalities, depression, bipolar conditions, and schizophrenia. The crew will have little opportunity for creativity, so they need not have creativity in their genome. Instead they have to be diligent in living out their lives and maintaining the ship. A bit of religiosity might be helpful, as well as a bit of obsessive attention to detail. The crew are technicians, medics, mothers, cooks, gardeners, cleaners, teachers, more like an order of nuns than swashbuckling heroes.

    I would also argue that you need as many species of non-human animals aboard as possible to provide companionship (to keep people sane and somewhat human) and possibly meat. Rabbits, small dogs, koi, and parrots would be a minimum. Goats would be nice for milk and meat if the ecology could support them. Extreme miniature horses would support the birth of larger equines on arrival, which would be priceless for colonists.

    This all sounds pretty weird, and it is. Generation ships are just about as unnatural as you can get shy of frozen embryos grown in artificial wombs and raised by AI nannies. But if it takes centuries to get to the stars, conventional thinking won’t get you there. All the taboos need to go out the window.

  • Astronist June 26, 2011, 16:55

    Joy, thanks for your reply. Obviously, I had shale gas in mind. If you are right in your implication that it cannot be extracted at an energy profit, then we’re back to space solar as the key to the future, and vehicles like Skylon (now under development in the UK) as the key to space solar. I’m comfortable with this.

    My view on the generation starship is the polar opposite of yours: such a vehicle will be closely based on generations of experience with space colonies, and will offer its occupants a very familiar environment. Without that experience, the starship will never be built: there will be no way of guaranteeing its viability or reliability over long periods of time. Plus, large space colony populations are needed to rack up the total energy budget of humanity, assuming that the starship can only consume a very small proportion of it (and disagreeing with Tobias Holbrook above, on the grounds that even fusion fuel costs money — in fact, especially fusion fuel, judging by the NIF experiments, or the highly engineered pellets in the Daedalus engine).

    Incidentally, in the latest posting but one at Starship Reckless, Athena Andreadis disagrees (currently bottom comment) with my assumption that a multi-generation starship will work with 100 to 1000 passengers on board. She thinks more people will be needed, both to cover all necessary skills and for genetic variety. Athena knows a thing or two about biology, so she must be listened to, but I wonder whether she is sometimes too pessimistic about future possibilities.


  • David June 26, 2011, 21:53


    We have a propulsion method now if we want to use them this way.
    I always though Project orion needed another look because 3-8% light speed is something that needs another look.

    It could be a jobs project now and we could as Carl Sagan said put our nukes to good use

  • Nathan Currier June 26, 2011, 23:59

    Joy, Astronist:

    The elites show no interest in space for a very specific reason: They are afraid of the freedom we might find out there. We might realize that a precarious existence without their meddling is better than this coddled prison planet they have created. We might brain-drain their hampster wheel. We might even compete with them. It would be much better for us to be stuck here under their worldwide financial dictatorship, wallowing in eternal serfdom and ignorance, without even realizing we are prisoners. Space is fine for pork barreling, but we will never be allowed to go off the reservation in any meaningful way. That is why they killed the space program and SETI. If we want to claim our transhuman future and our manifest destiny among the stars, we must kill the puppetmasters.

  • Andrew W June 27, 2011, 1:44

    It’s all too far in the future to make meaningful predictions, I personally have a soft spot for generation ships of gargantuan size, dozens of O’Neil colonies connected to a 100’s km long fuel tank, millions of people, fusion engines big enough to use H-bombs in the same way that the old bang-bang Orion was going to use A-bombs.

    In such an endevour the fuel would mostly be just deuterium and tritium, and the people going would be taking home with them.

    It would be financed by the voyagers themselves, which is more realistic than the state financing of a project with no financial gain and negligible political gain.

    All reminiscent of the way humans in self supporting bands colonized the continents of this world.

  • Joy June 27, 2011, 6:49

    Hi Stephen,

    Regarding shale gas, it is mainly a share market scam, more hype than real promise. The term in the financial community for such investment schemes is “pump (up the price) and dump (the shares)”. The industry insiders who blog on theoildrum (dotcom) have had many good posts on the practice. The well cost is much higher than conventional wells. Initial flows are fantastic, but the depletion rate is as high as 90% the first year. There are also environmental issues with water table pollution. Gas company execs talk optimistically to the media, then quietly do insider selling. Still there are a good 10^12 or so BOE of gas we will be able to get with good EROEI, and that is a good thing.

    Robert Zubrin was quite skeptical about the economics of solar power satellites in his book Entering Space, (a summary of his argument is posted at yahoo answers). Still, no one would be happier than me if Skylon flies, and reduces the cost to orbit!

    I disagree that generation ships are like space colonies at all. Psychologically, they could not be more different. Even on a remote space colony 6 light hours out in the Kuiper belt you could email Earth during dinner and get a reply before breakfast. Get even 6 light months out on a generation ship, and you are cognitively alone, communication which a one year time lag is nearly useless. Also, presumably people on a space colony would be doing something productive. Their system is not closed, they can probably visit other colonies, modify or expand their own colony. The generation ship crew (really more like human cargo) is just marking time, for their entire lives.

    IMO, the generation ship needs to largely care for itself. The purpose of the crew is to care for themselves without going crazy and fighting amongst themselves or sabotaging the ship out of ennui. For this reason, the smaller the crew the better. All of the specialized skills would have to be stored on memory chips, to be retrieved by the crew as needed. Also a small crew means a lower mass ship which is good. Finally, I would rather launch 100 ships with 10 crew each rather than one ship with 1000 crew. Let Lady Luck and Darwin sort them out.

    Really, all a warm body generation ship needs to succeed is to deliver a few functioning human uteri to the destination, the exploration crew could be born and raised on arrival from totally different genetic stock. (Of note, I had a 7th great grandmother who had 16 singleton births who lived to adulthood, don’t underestimate the human ability to multiply!) If feasible, the optimal (and more ethical) solution to generation ships would be to design a line of transgenic goats with humanized uteri. Goats are reasonably sized, eat simple fodder, and produce human like milk even without genetic modification. The generations of ordinary goats would endure the entire transit under AI (or expert system) supervision. The penultimate generation of ordinary goats would be implanted with embryos from transgenic goats. The transgenic goats could then be implanted with human embryos to birth the colonists. Then the AI gets to be nanny – despite the obvious concerns. (Alistair Reynolds thought the people produced by such a process would be psychologically quite odd)

    It sounds weird and sick, but believe me, the last thing you want in a generation ship is a small town that people are unable to leave, ever. I have lived in a New Zealand village for the last 30 months, and it feels like 30 years. We had 2 murders a couple of years ago, and there would have been many more if people couldn’t move away!

  • Joy June 27, 2011, 6:58

    PS: I am a bluewater sailor. I have found that the thing most likely to break on a modern sailing yacht is the crew! The boats have been known to do just fine for months at sea after the crew panicked and abandoned them. The more people on a boat, the higher the risk of politics, and even mutiny. Seriously, the German naval academy sail training ship had a mutiny last year, even with military discipline. On the best voyages, a small crew works like a well functioning family, with an unquestioned head.

  • Tobias Holbrook June 27, 2011, 7:48

    “Plus, large space colony populations are needed to rack up the total energy budget of humanity, assuming that the starship can only consume a very small proportion of it (and disagreeing with Tobias Holbrook above, on the grounds that even fusion fuel costs money — in fact, especially fusion fuel, judging by the NIF experiments, or the highly engineered pellets in the Daedalus engine).”
    However, the point still stands – if we have fusion, it is not the energy budget that matters, but the monetary budget. At the moment, we have no way of knowing how much the fuel may cost – if we have Polywell reactors, it could be very cheap indeed. Just because one propulsion method requires precision engineered fuel pellets, it doesn’t mean all will. If we’re limited to thermonuclear Orion, then we’d be limited by the cost of Lithium – how much would a purpose built fusion pulse unit facotry be able to get the price down to?

  • Kelly Starks June 27, 2011, 12:25

    >== My prior expectations were that colony ships would need to be so
    > immense and complicated that they would take longer to develop than a
    > fast probe to Alpha Centauri. The energy study showed otherwise.
    > Kinetic energy is linear in mass, and goes as the square of speed. That
    > means if the ship is twice as massive, it requires twice as much energy,
    > but if it goes twice as fast, it requires FOUR times the energy. Colony
    > ships do not need to go fast. They only need to drift, carrying a segment
    > of humanity. ==

    I think your jumping to conclusions here and skipping other factors. A slow drifting colony ship needs to be staggeringly huge. The crew size needs to be several times the size of the “working crew” due to normal population patterns with children and retired elderly, support staffs for same etc. Then you need to multiply that population possibly be orders of magnitude since you need the complete industrial base necessary to refine/recycle raw materials, and process and build those up to every part necessary to build the ship. Pretty much nothing lasts more than a few decades without major rework. So if your ships expected to have a service life more then 20-30 years crew and ship need replacement IN FLIGHT!
    On the other hand if you pour that mass into fuel (make the ship 90%+ fusion fuel by weight, and boost it out of Sol with Maser/Laser sails or something. Refuel in the target solar system, Maser brake on entry to Sol.) your comparatively tiny, shorter service life, ship can go at far higher speeds, and get there and back in a couple decades, not several generations. Since fuel costs a lot less in money or resources then the systems necessary to make a floating nation and the crew and ship size could be orders of magnitude smaller

    Another point is anthropologists note no current technological Nation has the breadth of skills in its population to fully operate and maintain itself without trade, and suggest it would take at least millions (maybe tens of millions) of people with very advanced technology, to be a self sufficient. Again this suggests a smaller, more energy intensive ship, would be far more doable then a bigger more energy efficient colony ship, with a dry weight of ship, supplies, or, etc, that could be thousands of times(maybe a million times) greater.

  • ljk June 27, 2011, 12:36

    Just as most fiction about alien intelligences portrays them as hostile invaders because that is what the majority of Hollywood and book publishers think the public wants from their stories about aliens, I have to wonder if the same applies to life aboard multigenerational starships? While not ignoring the many flaws and limitations of human nature, would life in such a world tend towards degeneration? I know it makes for an interesting story (I will always remember my first encounter with Heinlein’s Orphans of the Sky), but is it any more accurate than all those alien attacker stories?

    Since at present we know that we have a better chance of a slow starship becoming a reality in the relatively near future than anything relativistic or FTL, we need to really study the possibility of such a model and put aside the bias of the social degeneration story if we ever want to find out if such a way is feasible.

    However, I must add that I think by the time we do have real interstellar capabilities, our descendants will have changed enough that our vision of a multigenerational starship will be as outmoded as Verne’s lunar ship and perhaps even unnecessary. The minds that may leave our Sol system for the wider galaxy may be the ones we build.

  • ljk June 27, 2011, 12:55

    To add to my previous post:

    Assuming that multigenerational starships are built with human crews similar to us, one big advantage and incentive they may have to remaining whole, functioning, and sane as a society and individuals is a tangible goal. They will know with more certainty than most of us on Earth do now that their lives are dedicated to the task of reaching another world to both explore it and found a colony. Even those generations who exist during the journey who won’t live to see that day will know that their descendants will have a positive future already established and that they were an essential part of this process.

    This mission goal will even have the advantge over a religion that espouses happiness in an afterlife (assuming you’ve been a good boy or girl) of the fact that the destination is a real tangible place and those who will get to experience it directly will be alive when they do get there.

    This is I know people need more than just this, but a secure future which people have direct control over can only be a benefit. But I still have the feeling that, barring some kind of planetary disaster or an inability to reach the stars by any other feasible method, this is not how we will journey into the galaxy.

  • jkittlejr June 27, 2011, 13:02

    On the fusion front, I am surprised no one has mentioned the Z pinch machines as a way to make an Orion-like project feasible. Given the very high temperatures already achieved , even D-D fusion is not out of the question. The yields on individual shots can be less than a kilo ton, much more manageable than thermonuclear bomb. the equipment is much less exotic than NIF and you do not need uranium. A ship using a Z pinch poered drive could refuel from an icy body like Ceres or Callisto, of even a Kuiper Belt object. BY THE WAY is anyone suspicious of the deep silence that has come over the whole Z- pinch program? ( ok I am not a conspiracy theorist- it is just interesting that the this very exciting technology for creating billion + degree plasmas has no new news in three years. )

    Finally the experience of the Polynesians may be informativeWhen thinking about the drive to go beyond the solar system. When a small island community reached its resource limits, some people would leave the island in a sort of “suicide by sea” mission. They would trake out in canoe and try to find a new home. Most perished, but a few survived to win the darwin lottery- a new island to expand their population. This is JUST HOW WE ARE WIRED. As for some of the previous comments- no, the elites did not get in to the exploration boats for obvious reasons. -but they did like to use the method to control the population. Practically, the 100 year plan is really a fifty year plan to initiate colonization of the solar system. The answer at the back of the book is easy – we will not launch the first interstellar ship from earth, but maybe from an Earth – colony. Perhaps a space colony will capture a small icy body and exit the system for political economic or religious reasons. To paraphrase the quote- The future will rhyme with the past

  • Kenneth Harmon June 27, 2011, 14:43

    To Marc Millis and All,

    Many excellent ideas in Marc’s article and in the posts. The question is this. Assuming we find a potential habitable destination around Alpha Centuari over the next few decades, and given the known constraints so well laid out by Marc Millis and others, what are some potential “game-changers” aside from the standard “new physics” that would allow a manned trip to be launched to Alpha Centauri by the end of the 21st Century? For the sake of argument lets say 85 years from next year, i.e. 2097 as the launch date with a one way travel time not to exceed 50 years (Earth time) and hopefully far less? Given projected Energy budgets constraints laid out by Marc and others, and assuming there was a pressing need to get there, how might we start to rethink the problem to make this possible as an natural ” expansion option” to the Interplanetary colonization which most of us hope and assume will be going on by the end of the 21st Century.

    Barring radical new physics or some other completely unforeseen development it seems pretty safe to assume that at least for the 21st Century (and probably the 22nd and 23rd Centuries as well) the only Interstellar Travel option that may be even remotely fesible for Humanity is to our nearest neighbor, i.e. Alpha Centuari. That is of course unless Pete Kurzweil is right and we advance 20,000 years over the next 90 years or so. That said, given how relatively close Alpha Centauri is to Sol/Terra we should not give up on getting there in the relative near term if there is something of interest to go and explore. Obviously, the World would have to be a much different place from today to mount such a mission in the relative near term, but in some ways it can be argued that a trip to Alpha Centauri despite the Trillions of miles involved is simply a greatly extended Interplanetary Mission out to the farthest reaches of our Solar System. Beyond about 4.3 light years things get much harder , much quicker.

  • henk June 27, 2011, 16:01

    it is a high chance that alpha centauri has a habitable world. And if we find it we do not really need ftl drives to get there.

  • Paul Gilster June 27, 2011, 16:40

    henk, not everyone would agree with you that there is a high chance for planets around the Alpha Centauri stars. We’ll probably learn the answer soon, but there is still a lot of debate about what we might expect.

  • Andrew W June 27, 2011, 16:41

    If it were population pressure that drove the first interstellar colonists, think about how big that population would have to be, think about how many people would have to depart to make a difference.

  • Joy June 27, 2011, 18:25

    @Nathan Currier

    I agree 100%. Plus our global prison system is getting less coddled all the time. The days of pushing easy credit, prozac, welfare benefits, and trashy celebrity culture (what Huxley warned us about) are giving way to an in your face worldwide police state, forever wars, torture, warrantless searches, imprisonment without trial (what Orwell warned us about).

    As inefficient and expensive as the space shuttles were, I am told we could launch 4 shuttles a day for what the imperial legions spend on air conditioning. Not to mention the endless banker bailouts, now circa 2 x 10^13 USD and still soaring. Freedom can’t be established in space until it is reestablished on Earth.

  • mike June 27, 2011, 18:59

    great insights into the interstellar flight paradigm.
    technology does has limits. us humans are having trouble with atomic energy.

    we tend to put the reactors in areas prone to natural disasters.

    engineers take orders from the wealthy elite. the elite want to save money to
    quicken payback. so atomic reactors go on seismic fault lines and in flood zones. things look very bad for japan and very scary for the flooding mid west of the usa.

    i remember apollo 1. didnt that capsule catch fire and result in the death of the crew? the fire was from using pure oxygen.

    look at the space shuttle failures. boeing designed and built a commercial airliner using just a computer without real world modeling. the doors popped off. other jet planes have the roofs peal back from faulty riveting.

    i say any interstellar spaceship is going to have reliability problems and unforeseen design flaws. the smartest men make the biggest mistakes.

    the pioneer and voyager space craft are doing just fine. so are many others.
    why do some fail and some succeed? THAT is what needs to be researched.

    and…machines will always be more reliable than humans. will alcohol and other mind altering substances be allowed on star ships? what role will recreational sex have? what limits to consensus, consent and dissent?

    will money or other exchange mediums be in use for large crews? will crew members lie, cheat, steal and murder? will the star ship need cops and judges and lawyers and jails?

    i used to be an optimist. now i have grave doubts about the human condition.

    right now playing in movies houses across planets within 1o light years,

    (in 3d).

  • Andrew W June 27, 2011, 19:18

    Nathan Currier: “The elites show no interest in space for a very specific reason: They are afraid of the freedom we might find out there.”

    I think the reality is that space is important to hardy anyone, just compare the number of people commenting on space related sites compared to, well, just about anything else related sites.

    “If we want to claim our transhuman future and our manifest destiny among the stars, we must kill the puppetmasters.”

    Isn’t that the logic that Lenin worked with?

  • jkittlejr June 27, 2011, 22:54

    Just to make it clear- The people who explore the universe will be successful but not comfortable here on earth. Equipment will fail, lives will be lost and motivations to go forward will be impure. It will be a combination of inspiration, greed, pettyness, leadership, error and correction that will move us though these trials. it will be individual achievement and collective action. Our descendents will be much like us, they bear our genes and our designs. But would you really have it any other way?
    I think we have t learn to live and thrive in many sites the solar system before we can contemplate moving on the the next.
    Hey does anyone have nay new info or insight into adapting Z-pinch technology to propulsion systems? I could see it as a means to accelerate matter for reaction drives, or to fuse elements for energy generation- or both.

  • Marc G Millis June 28, 2011, 8:57

    Wow! I had no idea that a post on impartiality would provoke this level of discussion. I am impressed with many of the comments. With all these good points, the challenge is to find accurate answers. Right now, I’m a bit overwhelmed with how to capture and distill these into attackable problem sets.

    That said, many of you made assertions or framed questions that could be the basis of more detailed, helpful assessments. I challenge you to take those to the next level. Rather than just post these as comments, dig deeper, work impartially, and submit what you learned to the JBIS or other suitable journal.

    For those making assertions, treat your assertion as a hypothesis and then examine both supporting and dissenting facts to see what the real situation is today. Per what I wrote about impartiality – please do not try and ‘prove’ your points, but instead investigate the factors. (Did you include the infrastructure requirements? What is the level of certainty in the estimates? What is the difference between what has been actually demonstrated verses projected?) Be open to the possibility that your pet idea is missing some links in the chain. And then share what you learned. Rather than trying to prove a point or win an argument, apply that enthusiasm to dig out the facts as they are. Figure out what really needs to be done next, rather than just advocating pet ideas.

    For those framing questions (such as minimum population size, the affects of the human character on colony ships, etc.), I would love to see those fleshed out more explicitly. Again, a JBIS submission might be a good way to vet those. The first step of the scientific method is to define the problem. With these challenges, that first step has not yet been taken.

    In both cases of examining assertions and defining questions, I would really like to see those distilled down to a set of next-step questions that students of all ages can start answering… and answer those with impartiality and rigor so that we can rely on those findings to make decisions of the subsequent steps. By chipping away at these questions we will eventually figure out how to make all the dreams and benefits of starflight a reality.

    Ad astra, incrementis!

  • Ronald June 28, 2011, 12:00

    Just a few small remarks on the above interesting discussion thread:

    – It is wrong, even rather naive to equate population growth to economic growth and energy consumption growth: what we need tot enable future interstellar travel is indeed economic growth plus energy consumption growth, but both do not primarily depend on population size.
    – There is no foreseeable limit to technological and economic growth.
    – Our energy options are huge, contrary to certain pessimistic sounds (such as from Joy): not only uranium fission but also thorium (LFTR), solar, and ultimately fusion. It is factually wrong, even ludicrous, to suggest that fusion power can not have a positive EROEI. The potential EROEI of fusion is probably the greatest of all known energy sources.
    – We are not running out of raw materials any time soon, again a naively pessimistic view. Just out of some kinds of raw materials. Just as a few centuries ago humans were running out of whale oil. The earth is still very, very rich.

    See for some EROEI example data for instance:

  • Astronist June 28, 2011, 19:36

    Concerning the psychology and activities on a generation ship. Joy wrote that the generation ship crew “is just marking time, for their entire lives”. I disagree with this, for two reasons. Firstly, they will be getting on with their lives just as we do. They will have jobs to go to, leisure time to spend, and political arguments to resolve. Secondly, the radio time lag will disrupt two-way communication, but not one-way communication. Specifically, since the ship is necessarily much smaller than the home culture it has left, that culture will be producing innovations in science, technology and the arts. The passengers on the ship will therefore be spending much of their time catching up with the latest from the Solar System. Innovations in nanotech and biology would be particularly applicable to the starship’s activities after arrival. So just as the Voyager probes were reprogrammed in flight (I believe I’m correct in this) and reached their goals with more capabilities than they had when they left Earth, so the starship will also upgrade its technologies in flight.

    Would anyone claim that we are merely “marking time”, just because we’re not travelling to the stars, or (in most people’s case) not even thinking of doing so?

    However, I take the point about small communities. Though we can’t predict how community interactions may be modified by developments in computers, it may be that a larger community would be more stable than a smaller one, so we’re back to the worldship concept that I need to think about for the upcoming BIS meeting later this summer!


  • Kelly Starks June 29, 2011, 12:07

    > “is just marking time, for their entire lives”.

    Really they are. In our lives here we can advance our company in the industry, changes in politics, etc. The generation ships crews are just care takers for the generations it takes to get there. They are just ther to keep the seats warm until the planned for explorer generation gets to do something.

    Worse for us, the kinds of people who would be good at and volunteer to be caretakers – are not generally the kind of people who would make good explorers/developers. So your effectively going to stock your ship with the wrong “bloodlines” for what you want when you get there.

  • Astronist June 29, 2011, 13:52

    Kelly Starks: but why do you think that there will be no industry or politics on a starship? Are you thinking of a small vehicle with a Space Shuttle sized crew? But how about a worldship with several thousand passengers? Why do you think their work maintaining their vessel and life-support systems, developing their own culture, keeping up with a flood of news and innovations coming in on the radio from the Solar System and from other starships, perhaps doing their own research into areas like biology and nanotech which can be studied in small-scale on-board laboratories, managing their lives with limited resources (just like we do on Earth), would amount to being no more than caretakers?


  • Astronist June 29, 2011, 14:01

    Marc, I am currently writing up an article on population / energy size for JBIS. Have found your recent article (200 years to get economy large enough to launch starships), and am taking that into account.

    What really needs to be done next: as I said above: get it into people’s heads that a sustainable future involves both a falling-off of growth on Earth and an acceleration of growth in space!


  • Eniac June 29, 2011, 23:43

    What nobody seems to realize (except Kelly) is that we do not only need to bring people, but also a full complement of our technology. This is not trivial. In all former episodes of colonization, people could either live off the land, take from the natives, or had continuous supply lines from home.

    Here we are talking about truly autonomous colony ships, ones that would be able to build a highly advanced industry from scratch with only natural and ship’s resources. If you really start thinking about it, you will see how mind-boggling it is. A somewhat amusing but relevant illustration of this is the Toaster Project, in which Thomas Thwaites takes up Douglas Adams and attempts to build a toaster from scratch…. (http://www.thetoasterproject.org/)

    Despite the difficulty, it is my view that we will learn how to build an industry from scratch before we can build a starship. It is also my view that we will do so in a completely automated manner, because current technology permits it and it will in the end be easier than relying on unreliable humans as cogs in the machine. Particularly if this project unfolds in space, where it is most useful and relevant, and where human labor is extremely expensive. See this site for the best information on this general subject: http://www.molecularassembler.com/KSRM.htm

    If this happens, there will no longer be heroic pioneers (do they even still exist now?), even in interstellar travel. Robotic ships will precede us wherever we wish to go, and if we decide to follow ourselves, we will make sure that a working economy and safe habitats are ready at the destination, and that all the potential dangers in transit have been well ironed out. The trouble I have is in understanding why we would bother moving our bodies this far, given that our machines, of course, will have eyes and ears and we can get the full benefit of being there without being there…

  • Eniac June 30, 2011, 0:08

    The prevalent attitude of doom and gloom about overpopulation, lack of resources, police state, etc. etc. among the commenters here is truly astonishing. I would have least expected this from a group such as this. There has been lack of resources many, many times in the past, to be promptly relegated to irrelevance by new technology or simply alternate ways of doing things. Whale oil is a good example that has been mentioned.

    There is no evidence at all for a slowdown in the growth of technology, to the contrary, progress in electronics and biology has never been faster than today. Robotics and medicine are poised to capitalize on these developments in a very big way. Nanotechnology is at the horizon to really make things interesting. We do not really need more energy than we use now, and that much can be supplied for thousands of years in several different, well understood ways. Plenty of time to come up with new and better ways. To take the current moderate economic downturn as an indication that our best days are behind us is ludicrous. Politics is no worse than it always was, and 1984 no closer than when it was written.

    Just felt I had to say this, to counteract a potential mass-hysteria on the forum….

  • Rob Henry June 30, 2011, 4:22

    We can only have a very low level of certainty in our future. It seems a human tendency to only believe that the future will be bright or gloomy, and nothing in between. Comments here reflect well researched and tightly argued version that reflect each extremity, but I can’t help feeling that the reality will fall somewhere in between.

    Even in the most dire version of our future, I not sure that space travel is off limits. It is hard to halt the onward march of knowledge on technology and science irrespective of prevailing living standards. I am also neigh certain that the current cost of manned space flight is inflated by high price of life in our current modern world. If the value of human life was to tragically plummet due to an energy crisis, one of the few benefits is that space might become more accessible.

    Perhaps we will begin colonisation of our solar system, if not interstellar travel, under far less glorious circumstances than most today conceive.

  • Kelly Starks June 30, 2011, 12:40

    > Astronist June 29, 2011 at 13:52
    > Kelly Starks: but why do you think that there will be no industry
    > or politics on a starship? ==

    None would be a little extreme, but how much “industry” is there on a cruise ship or naval vessel? (Or small town?) There’s no one beyond the ship to sell to. No way they can pay you (other then subscriptions to news/data feeds). No new raw materials to develop.

    In the ship you can really expand or develop the ship much since you launch with all the material/facilities your going to have until you reach the target star system. You’re just refurbishing the old systems.

    Research similarly is strangled by limited personnel and resources – and you can’t afford to take a lot of risks.

    Now just to maintain a ship capable of going for generations likely could take millions of people to tear it down, recycle, and remanufacture the same stuff, etc. But that’s maintenance, being a caretaker – not developing or building.

    > == keeping up with a flood of news and innovations coming in on
    > the radio from the Solar System and from other starships, =
    Listening to others doing new adn exciting things they can’t do.

  • Kelly Starks June 30, 2011, 13:47

    > Eniac June 29, 2011 at 23:43
    > What nobody seems to realize (except Kelly) ==

    To be fair I spent more then a little time thinking about it. Me and a group got into the idea in the mid 90’s
    Starship Design Project

    Links are somewhat the worse for wear. Sorry, I can’t access them for maintenence.

    Oh, a particular fast starship idea, using near term fusion systesm (Bussard’s Polywell reactors actually) I came up with is at:
    Which I thought might be able to cruise at 40% of light speed.

    >== is that we do not only need to bring people, but also a full complement
    > of our technology. This is not trivial. ==
    >== Here we are talking about truly autonomous colony ships, ones that
    > would be able to build a highly advanced industry from scratch with
    > only natural and ship’s resources. If you really start thinking about it,
    > you will see how mind-boggling it is. A somewhat amusing but
    > relevant illustration of this is the Toaster Project, in which Thomas
    > Thwaites takes up Douglas Adams and attempts to build a toaster from scratch…. (http://www.thetoasterproject.org/)


    Only think I can add is – on the ship it would be worse. NO raw materials to mine. All you can to is re-cannibalize the ship over and over. I suppose a plus would be the ships made of refined materials (metals are the most easily recyclable materials known) but try building a new IC chip from old scrap some time? Worse, what if the really cool super chips the broadcasts talk about need a element you never thought to add to the ships stocks?

  • Kenneth Harmon July 1, 2011, 0:25

    Eniac and All,

    First, I generally agree with Rob Henry on how the foreseeable future is going to unfold. In all likelihood it will turn out somewhere between the bright and the gloomy scenarios. However, even though I firmly believe in accelerating Scientific and Technical progress and especially in the areas of Nano-technology, AI and Medicine, let me also briefly give you the Pessimists case 0ver the course of Century or so.

    I am not a doomsdayer, but when I lo0k at longer term trends and where Humanity seems to be heading by the end of the 21st Century a couple of huge challenges emerge. That is unless Pete Kurzweil is correct, and we hit a singularity event over the next 40-90 years and advance the equivalent of 20,000 years over the next ~100 years. If that happens then all bets are off since both Humanity and Human Civilization will be completely transformed. Unfortunately, the more likely scenario is that we hit a major S Curve or Plataeu along the way, which is why Kurzweil may be just a little optimisitc in his projections about the next ~90 years. If we hit a major S curve on technology innovation circa 2025-2060 or so as some experts are projecting then we may be in a very dangerous transition period f0r many decades to come.

    The first of our biggest challenges over the next ~90 years is our own success as a Species. We have proven again and again that we can recover from Human folly, but success is a different story—big problem. In 1960 our planet had a Human Population of ~3 Billion, by 2025 we will have 8 Billion and counting as we are fruitful and multiple. Simply put, we are wearing the place out very quickly. To many people and a finite set of key resources in the near term (next 25 years) make for a truly explosive combination and we have Nukes now which could lead to some massive destruction as a result. For example, fresh water and potential food scarcity due mainly to transportation challenges (peak oil, 2o20?). Scarcity is a bad problem and while we may be able to innovate and adjust if we have enough time the question is will we have enough time before some serious catastrophe befalls Human Civilization as a result.

    The second major challenge is linked to the first, but may prove to be even more vexing. Given the accelerating progress of bio-technology and nano-technology in particuliar, by mid Century smaller and smaller groups of people perhaps down to a single crazy individual genius (Think the Unibomber as a Bio-tech expert) will be able to do in a Billion people at a shot. Again, if given enough time Humanity can innovate and adjust, but will we have that time?

    Do I believe Human Civilization is going to collapse within the next 25 years given these challenges, of course not, but over the course of the next 100 years or so things become much more problematic. The point is that we are in a real horse race between our innovation and adaptability on the one hand and our primitive natures and scarcity problems on the other hand. We may indeed prevail, but it will no doubt be a very close race and Humans are not very good longer term planners. Consequently, if we make it another 100 years or so without a causing a very serious setback to Human Civilization it will be a minor miracle.

    The real problem is the transition period where people become desperate, and yet they have very destructive technology at hand to try and change things in their favor. And then of course there is also the potential of the rise of hostile AI to Humanity by the end of the 21st Century. I do not believe the threat is that we will be wiped out as a species by these and many other very dangerous challenges (the usual Climate Change, War, Pandemic, etc) but preserving an increasingly fragile Human Civilization increasingly prone to a catastrophic single point failure over the course of the next ~100 years will be very hard. If we are unlucky we could see a new Dark Ages by the end of the 21st Century.

    Hopefully we will beat the odds, but I am also into Insurance and back-up plans ASAP just in case. This is why I have repeatedly challenged us all in this forum to think about ways to break out of the many technology constraints we face in Human Interstellar Travel such as the Millis calculations on available energy, and seek true game changers and short cuts. If, and admittedly this is a big if, Humanity finds a habitable planet somewhere within 12 Lyrs of Sol/Terra we should strive as a moral imperative (preservation through diversification and relocation of the Species) to send a Colony ship within the next ~90 years to that destination once we understand that it is not already inhabited by Intelligent life. Given today’s constraints and politics this goal or moral imperative may seem to be pure fantasy. However, throw a real scare into Humanity about the long term existence of our Civilization (another World War might do it), and suddenly finding 10 Trillion to do this may seem very possible provided we have developed the enabling techology and engineering over the next 50-75 years to do this and we get lucky with a relatively close destination. Lots of ifs, but it may be all we have.

    The real argument here is that as hard and expensive as Interstellar travel may be in the nearer term we may have a unique opportunity late in the 21st Century to do it on an urgent basis before various challenges temporarily overwhelm our Civilization and close the window of opportunity for a while, In time we are likely to recover and be a much more mature Civilization, as we “go in style”, but for now lets “think big and early”(our Grand-children) since we have everything to gain and nothing to loose by doing so. Good luck is when opportunity meets preparation and our task is to develop the concepts and technology tools to do this with a real sense of urgency should political and Economic conditions change. The Old Orion approach is a good place to start and perhaps Icarus might show us the nearer term path ahead.

    Finally, never forget that the Millis Energy calculations say “best case” we may have to wait only 200 years (~2200 CE) for the first Interstellar Mission, but then goes on to project much more likely periods of circa 2500 CE, 2600 CE and beyond. This is a very long time to wait. I would argue that it may be an even bigger miracle for our current Human Civilization to thrive and prosper for as long as another 200-500 more years to enable Interstellar travel on an orderly and realistic basis as oppossed to making a highly risky move and sending a large Colony ship traveling at .1-.3C to a star within 12 Lyrs of Sol/Terra by the end of the 21st Century. They are certainly not exclusive objectives, but rather then thinking about all of the reasons why we can’t do it, perhaps now is the time to start thinking about ways we can given known constraints and despite how our current Elites may have temporarily turned their backs on Space. Do we really believe that 50-60 years from now this will still be the prevaling wisdom of those generations? Again, we must think big with both hope and a sense of urgency and purpose. It would be nice to believe we have 200-500 years, but we should plan as if we have less then a hundred years to launch a Human Colony ship into the Interstellar void. Ultimately, we may have no choice and time may be shorter then we think. So how do we find a way around the Millis Energy constraints for starters?

  • David Portree July 1, 2011, 1:04


    I’ve commented on your efforts to apply science to predicting the future previously. You might as well stick with your more optimistic prediction for interstellar travel, for it means exactly as much as your new, more pessimistic prediction. Future prediction is sometimes reassuring, sometimes scary, but always based on far too little information to be truly useful. I base these observations on my study of history, which shows clearly that human events are not predictable. That extends to politics, technology, science, social mores – anything you’d care to mention. History is just one damned thing after another, and so will be the future.

    Best regards –


  • Tobias Holbrook July 1, 2011, 6:10

    Re. The Toaster Project – that’s not quite accurate, since one would not be working alone. Also, attempting to replicate the exact design of the toaster makes it harder than it has to be… and a clay toaster, rather than a plastic one, is just that much cooler anyway. Besides, if you want to make an apple pie from scratch, you must first create the universe.

    The question of how big an industrial seed needs to be is a critical one, and one which should be a very impiortant issue for the 100 year starship study.