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Odds on the Human Future

I’m not very good at playing odds, though I do seem to pick up money routinely from a friend who is a Chicago Cubs fan (this year may be different — we’ll see). But bringing odds into the discussion of the Fermi Paradox can be an interesting exercise, and Princeton astrophysicist Richard Gott has already given the matter some thought. Let’s assume, for example, that you and I are not particularly special. We’re simply representative of the living beings who populate the universe.

If that’s the case, the odds say we’re probably living in one of the older civilizations, and one of the larger ones. That’s because more people would have lived in these cultures than in short-lived, smaller civilizations. It’s the Copernican principle at work, the notion that there is nothing special about the particular moment at which we’re observing what’s around us. Gott would say this has implications for other worlds.

“The sobering facts,” Dr. Gott says, “are that in a 13.7 billion-year-old universe, we’ve only been around 200,000 years, and we’re only on one tiny planet. The Copernican answer to Enrico Fermi’s famous question — Where are the extraterrestrials? — is that a significant fraction must be sitting on their home planets.”

Must be sitting there, that is, because that is precisely what we find ourselves doing. As to the argument that scientific progress is unstoppable, Dr. Gott notes in this New York Times article (from which the above quote is drawn) that civilizations like China’s abandoned exploration after making major inroads in world discovery. Just how representative was the Chinese experience? Indeed, the possibility exists that the window for a civilization to get into space and stay there is vanishingly small. We may not be at the beginning of the space program but near the middle of it. The odds on that are 50 percent.

We’re now entering a philosophical debate that is rather robust, and needless to say, Dr. Gott has his critics as well as his supporters. Here’s a link to an article by Bradley Monton and Brian Kierland that appeared in the Philosophical Quarterly (PDF warning). And have a look at John Tierney’s follow-up to his Times article. Here he quotes Monton (University of Kentucky) on Gott’s ideas on space colonization:

…I think Gott is right — it should be a major priority that we work on establishing self-sufficient colonies on other planets. Technology hasn’t been around very long, and in the absence of evidence this should lead us to think that it’s likely that it won’t be around very long in the future. But we shouldn’t be fatalistic about Copernican Principle predictions — there are things we can do to make it more likely that technology-adept intelligent life will continue to be around in the future. Besides the obvious things we can do (e.g. controlling loose nukes, preventing pandemics), establishing self-sufficient colonies will clearly make a difference.

Now ponder Gott’s analysis against the familiar science fiction idea that we are a young civilization moving into a galaxy filled with far advanced races. As Tierney notes, pick any American at random and you’ve probably picked one from a town that’s larger than median size, because that’s where the population is. Similarly, we’re probably in a relatively representative civilization right now. I like Tierney’s finish:

In fact, we could assume that the typical civilization reaches our stage of development, applies the Copernican principle, realizes that it’s 95-percent certain to go extinct unless it takes an extraordinary step like colonizing other planets — and then goes extinct even though it’s aware of its eventual doom.

Is that going to happen to us, too? What can we do to beat those odds?

Beating the odds is something we seem suited to doing. But it requires resolve and a commitment to living for more than the present. The stakes are huge, for if we cluster all our resources on a single world, we run the risk of losing everything. “Sooner or later something will get us if we stay on one planet,” says Gott. “By the time we’re in trouble and wish we had that colony on Mars, it may be too late.” That means we’d better get to Mars sooner rather than later before the window closes.

The Monton and Kierland article is “How to Predict Future Duration from Present Age,” The Philosophical Quarterly Volume 56, Number 222 (January 2006), pp. 16-38. Those familiar with Richard Gott (and I count myself a great admirer), will know about his Time Travel in Einstein’s Universe: The Physical Possibilities of Travel Through Time (New York: Houghton Mifflin, 2001), a book I can’t recommend too highly. A quote apropos to our work here: “…one of the things we should understand about time is that we have just a little.” Using it wisely should be our greatest concern.

Comments on this entry are closed.

  • Paul Dietz July 18, 2007, 11:12

    The problem I have with Gott’s idea is that, in a universe where no intelligent species go extinct quickly, the people at our stage of development would be making the same argument he is. And they’d be 100% wrong.

    How do we know we’re not in such a universe?

  • Christopher L. Bennett July 18, 2007, 12:34

    I find the China comparison a bit naive. The reason China didn’t expand and England/Europe did is because they had different material needs and circumstances. China was the most advanced, wealthy civilization on Earth at the time. They didn’t need to go out exploring, because they had everything anyone could want, and everyone else came to them. Conversely, England/Europe was actively interested in expansion and travel because they didn’t have the stuff that China did, and so they wanted the ability to travel to China and buy it from them; and then they pursued industrialization because they wanted the ability to compete with China’s wealth and power. (Of course this is all greatly simplified.)

    So it’s not as if civilizations exist in a vacuum and their choice to expand or not is entirely random. It’s a function of their circumstances and relations to one another. Let’s remember, we’re not talking about single cultures here; we’re talking about *planets.* And any given planet is going to have a range of different cultures in different environmental and economic circumstances. If a planet has a China analogue that rests on its laurels because it’s already as advanced and wealthy as it needs to be, then it probably also has a Europe analogue that covets the wealth and advancement of the China analog and pursues technological advancement to compete with it.

    And of course cultures come and go, and their circumstances change. Odds are that any given planet will be home to many different cultural types over its history. And out of all those different cultures, it only needs one that’s expansionistic, scientific, industrialized, etc. at the right time and for a great enough duration in order to expand into space. A single culture can’t be analogous to a whole planet any more than a single organ can be analogous to a whole body.

  • andy July 18, 2007, 12:57

    So it’s not as if civilizations exist in a vacuum

    …but planets, on the other hand, do.

    (sorry, couldn’t resist)

  • philw July 18, 2007, 13:12

    You’ve Gott to be kidding. His methodology does produce interesting predictions in the total absense of any other data but it is far from being fact. For example, like the space age, the digital age is of the same duration and moment. Anyone here think that we’ll suddenly stop the digital age in another 50 years like he surmises in the article regarding space exploration? No.

  • Chris Wren July 18, 2007, 18:11

    I’d consider it a pretty generous estimate if a galaxy like our produces maybe a few dozen advanced civilizations over it’s lifetime – (and perhaps some tens of thousands of intelligent species that don’t evolve technology: there are several intelligent species on this planet right now) It depends on what kind of anthropocentric assumptions we make about how “inevitable” technological development is.

    But even that number of a few dozen tech civilizations per galaxy could mean that ALL of those civlizations could miss each other by hundreds of thousands, if not millions of years. The galaxy is vast in time as well.

  • JS Berry July 18, 2007, 20:03

    Couldn’t someone apply Gott’s reasoning to the earliest human civilizations that took up farming and predict they would be back to living in trees and eating grubs and fruit in a few years because that is what they did for most of their existence? The first people to take up farming were certainly not living in a way representative of the average way people lived until then so the argument would be incorrect when applied to them. The conclusions he makes are kind of like saying I rolled a die one time and it came up 1 so that must be an average roll and I can expect to roll 1 more often than any other number. It is just illogical and unscientific. No one can know if we are average or exceptional until the entire time space continuum is explored so the analysis is useless.

  • philw July 18, 2007, 21:09

    Yes, the assumption of “average” is the Achilles Heel

  • Ronald July 19, 2007, 7:41

    I agree with all of you above ;-), particularly with Berry.

    There is a fundamental flaw in Gott’s reasoning. Most importantly, Gott assumes equal probability distribution or so-called ‘indifference’, making bold statements about things we simply do not know enough about (‘knowledge from ignorance’).

    I liked Tierney’s article, but even more so some of the comments below it (especially 59, 77, 80), excerpt:

    Simply put, the principle of indifference says that it you know nothing about a specified number of possible outcomes, you can assign them equal probability. This is exactly what Dr. Gott does when he assigns a probability of 2.5% to each of the 40 segments of a hypothetical lifetime. There are many problems with this seductively simple logic. The most fundamental one is that, as Keynes said, this procedure creates knowledge (specific probability statements) out of complete ignorance. The practical problem is that when applied in the problems that Dr. Gott addresses, it can justify virtually any answer.

    In addition, I think we should, to begin with, distinguish between 3 types of natural processes and phenomena:
    – those that just run their courses (like geyers, volcanoes, plants, animals, stars, etc.) with a given but sometimes unknown duration,
    – those where the chance of something ending it increases with increasing time (again plants, animals, species?, civilization?)
    – those where chances of survival actually get better with increasing time, due to things like learning, experience, determination, resistance (again animals, partic. humans, civilizations?).
    I presume there can be overlap between the 3 above types.

    Example: it is not so, that, the older people are, the longer their remaining lifespan is (unfortunately; well, apart from progress in medical science, etc, not relevant here); but it is an insurance fact that, the longer people have been driving (in their lives I mean, not in a single day), the smaller the chance that they will get an accident, due to experience and the like.

    It is very well possible, and hopefully, that the latter example applies to (human) civilization: that we gain so much experience, knowledge and ‘robustness’ that we increase our survival chances over time.

    Nevertheless, I agree with several commentors (commentators?), that, indeed, to increase human species’ and civilization’s chances of survival, we MUST spread beyond earth in self-sustaining colonies, first Mars, then the nearest (inhabitable or terraformable) exo-planets.

    I argued in a previous post why I do NOT believe in self-sustaining space colonies, like hollowed-out asteroids, generation ships etc., for the same reason that ships cannot stay at sea for ever: combination of resource depletion and ‘shit happens’.

  • Ronald July 19, 2007, 8:56

    Elaborating a little bit on my previous post:

    so it all boils down to 2 problems: a fundamental lack of knowledge and a too small sample size.

    We simply do not know the chance of a (technological) civilization (or even life, advanced life) arising, the lifespan of a technological civilization, etc.

    We do know (approximately) the lifespan of a mammal species, the number and lifespan of (all, not just techn.) civilizations on earth.

    The picture would change dramatically the moment we found life, even the simplest proto-bacterial, or even fossil bacterial, on Mars. Few people fully understand the importance of such a discovery, also from a statistical point of view, if we found any type of life on the plannet.

    Analogy: imagine you find yourself in a room in an immense building with an immense number of rooms. You have no idea whether you are alone or not, or how many others there are in the building. You open the next door on the corridor. You find somebody else in that room. It then immediately becomes extremely likely that there are many others in the building as well.

  • Hal O'Brien July 19, 2007, 14:10

    “Anyone here think that we’ll suddenly stop the digital age in another 50 years like he surmises in the article regarding space exploration?”

    A qualified yes.

    Remember he’s saying there’s a 50% chance of such a stoppage. When it comes to “the digital age” — by which I assume you mean networked computers used in the 100s of millions, distributed globally — the infrastructure for that is absolutely dependent on cheap energy. And the odds for that going away — and soon — are extremely high.

    So, yes. A 50% chance the digital age will go away? I don’t find such a prospect pleasant, but within the range of possible outcomes. Now, mind you, that also means a 50% chance it isn’t.

    An optimist believes we live in the best of all possible worlds. A pessimist fears this is true. :)

    PS: There is a vast gulf between, “anyone” and “most people.” H. Sap. is sufficiently diverse that such sweeping statements will be incorrect most of the time — there will almost always be exceptions.

  • philw July 19, 2007, 14:26

    Energy requirements per computation continue to DECREASE, and that’s without any societal pressure to conserve energy. We have many viable solutions to energy issues available today, increased conservation e.g. energy saving flourescent bulbs, wind power (except outside Ted Kennedy’s Hyannisport), solar power at higher cost but still viable, more nukes (designed with 21st century control systems and materials science). The list goes on and that’s without any breakthroughs or even nominal efficiency improvements.

  • Hal O'Brien July 19, 2007, 16:06

    Energy requirements per computation continue to DECREASE…

    At the chip level, sure.

    At the total production level — extracting the raw materials, assembling the components, moving them from place-to-place (frequently across oceans and continents), moving you to the retail store to buy, and supporting all the retail infrastructure to have it available to buy…

    Not so much.

    We have many viable solutions to energy issues available today…

    Global energy consumption today is about 15 terawatts. Oil, gas, and coal account for about 13TW of that, and all other sources for 2TW. If you have a magic potion to make that 2TW become six times larger to meet today’s requirements — and grow about 3% annually year-in, year-out, to meet future demand — then it’s “viable.” If not, then not. {shrug}

  • Hal O'Brien July 19, 2007, 16:11

    My mistake, I understated the problem. The 2TW has to grow by a factor of 7.5, not 6, to make it to current consumption of 15TW.

    If you have the data to show there’s enough slack in those 2TW to grow as much as needed, please show it. I’d be interested.

  • Ron S July 19, 2007, 16:22

    Interesting discussion. I earlier thought of typing something about why I thought Gott’s statistical reasoning was seriously wrong but I chose not to bother, so it is good to see much of what I was thinking nicely covered by others.

    As to the urgency of establishing off-Earth colonies to ensure our survival against a catastrophe, well I’m not so sure about that. My thinking on this is as follows. The catastrophe is either exogenous (such as getting squashed by a NEO or a super-virus so that nearly all human life is extinguished) or it’s innate (we stupidly or intentionally destroy ourselves with the many means at our ready disposal).

    In the former case, a remote colony is helpful. However if we pursue this option now it will be consume a large portion of human productivity, have a poor chance of success, and, selfishly, won’t help me or my kin and neighbors. I see that as a poor investment. Better in my view to invest in biotech and NEO search and destroy technologies. More certainty of a positive outcome, cheaper, and has benefits in the likelihood of no catastrophe.

    In the latter case, that is the seeds of our destruction are innate, you can run but you can’t hide. No matter how many colonies we build elsewhere, if destruction is writ large in our make-up as humans this will be no protection except perhaps to delay the inevitable. Better to stay home and keep evolving our cultural norms to build strong protections against these tendencies.

    Despite the above words, I am in favor of exploration and colonization. Not to save ourselves but to do what comes so naturally to us, which is to satisfy our curiosity and challenge ourselves, and maybe even improve ourselves along the way. This makes exploration less urgent but still important enough that we will certainly do it.

  • Peter Wakefield Sault July 20, 2007, 12:24

    ‘Big Bang’ is not science. Along with ‘Global Warming’ it merely heralds the birth of a New Dark Age.

  • Peter Wakefield Sault July 20, 2007, 12:42

    But for Christianity humanity would have been in space in 500AD. The Christians murdered the Hellenic philosophers, mathematicians and astronomers (‘devil worshippers’), burned their books (‘witchcraft’) and tore down their academies, not to mention burning the Great Library to the ground (“It was an accident, honest, guv!”) . Now there are too many of us and we’re all busily burning up our diminishing energy resources like there is no tomorrow. So, of course, there is no tomorrow. There is only a radioactive wasteland. We had our chance and we blew it.

  • philw July 20, 2007, 14:07

    Regarding TW. There’s coal aplenty. Dirty, but not leaving us without energy. Some $ cleanup required. There’s also coal tars and oil that’s politically unavailable or economically too pricey in the current market. Never said energy wouldn’t be more expensive. I was addressing computing whose energy costs will decrease by orders of magnitude. Expect less ‘business’ travel.

    Don’t forget old style fission nukes I mentioned.

    Then near future speculatively, there’s stuff like methane clathrates.

    Beyond that for 50 yrs out …well it’s like asking someone from 1957 to forecast today with PCs, cellphones, hybrid cars, the web, DNA analysis, whatever.

  • david July 20, 2007, 14:46

    I wonder if the window for getting into and staying in space has already passed. Not for lack of resources but because of politics.

    As an example suppose russia/china/someone was to build a space based laser for launching probes (laser sails). What would be the reaction of the US? Or if the US was to launch such a system, what would be the reaction of china/russia? Any such system capable of propelling a probe would also be capable to shooting down missiles. Politically to either side it would be unacceptable and would not happen.

    Humanity as a whole could afford a couple trillion dollars of space research and development a year if we were not focused on other issues, like war. That would be enough even without more efficient rockets to do a lot.

    Fermi’s paradox isn’t really a paradox. There are a thousand possible answers to it. We just need to get out there and start building the infrastructure so that our great great great grand children will find out what the correct answer is.

  • Administrator July 20, 2007, 15:04

    David nails the issue exactly. All I can do is quote him in admiration: “Fermi’s paradox isn’t really a paradox. There are a thousand possible answers to it. We just need to get out there and start building the infrastructure so that our great great great grand children will find out what the correct answer is.” Nice.

  • Paul Dietz July 20, 2007, 15:06

    ‘Big Bang’ is not science. Along with ‘Global Warming’ it merely heralds the birth of a New Dark Age.

    This is a troll, right? In case you honestly believe this, I can only express my pity.

    The Hot Big Bang is the only theory explaining the observational cosmological evidence, particularly the existence and properties of the cosmic microwave background radiation and the primordial composition of the universe. You might as well believe the earth is flat; that would be an intellectual error of the same order.

    It’s too bad for you if science has led to conclusions you don’t like, but unfortunately reality doesn’t care what you want.

  • Peter Wakefield Sault July 20, 2007, 16:09

    Paul Dietz uses all the tools available to the professional propagandist, but mainly ad hominem insults, to promote his adopted religion – ‘Big Bang’, a modern pseudo-scientific version of biblical creationism. In what way is ‘Big Bang’ testable, Paul? And what exactly do you mean by the “primordial composition” of the Universe? Were you there? Do you have photos?

    If the evidence leads to a logical absurdity then one does not automatically and without question accept that logical absurdity as the truth. One firstly tries to find the missing data and then to proceed to a non-absurd model. Even then it is not science but mere speculation. What you are doing. Paul, is to confuse a mathematical model – and a bad mathematical model at that, full of fudge factors and faith – with reality.

  • Adam July 20, 2007, 19:56

    Hi Paul Dietz

    He sure talks like a troll, doesn’t he?

    As for Xianity wrecking Greco-Roman science – what a lot of hooey. Xian scribes in monasteries kept Europe literate after the climactic disasters of the 6th century destroyed the old Empire. It was called the “Dark Ages” because of the lack of literary evidence, not because intellect went backwards.

    Experimental science was frowned upon by the Greeks, and inventive innovation was kept secret from other inventors because there was no such thing as “intellectual property”. Plus all the power and influence was wielded by either wealthy landowners or the military. Inventive merchantile societies didn’t arise until the Middle Ages and the growth of belief in human equality and the end of slavery – both Xian “inventions”. Slavery kept both the Greeks and Romans from expanding a power economy because they saw no need. Why else did the steam engine remain a toy for them?

    Xianity has been anti-Pagan but rarely anti-technology. Medieval Xian Europe saw the expansion of water-wells and wind-mills to a degree never seen in the pagan Empire, plus countless other inventions. The Greco-Roman pagans were fundamentally a conservative slave-based agrarian economy and thus effectively static. Starships by 500 AD? Don’t make me laugh.

  • Administrator July 21, 2007, 7:11

    We have suddenly begun to drift far off-topic here, and while these are interesting issues, they don’t fit well with our purpose. For new readers, let me explain that charter, as found on the title page: “Centauri Dreams looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities.” The topic in question in this post is Richard Gott’s theory about probability and its possible relevance to interstellar studies. Time to return to that focus.

  • Eric James July 21, 2007, 22:36

    I’m still fond of Isaac Asimov’s concept of the universe. Life is very simple (at best) where it exists, except on Earth. Higher order evolution is simply a freak of nature.

  • Administrator July 21, 2007, 22:51

    Eric, that gives us a straightforward answer to the Fermi paradox. We could expect, even with higher-order life as a rarity, that it might exist in numerous other places in the galaxy, but the odds on such widely separated places becoming aware of each other are long.

    I’m inclined to the rarity theory myself, but I also think about Greg Bear’s law: “No simple mathematical equation can provide a useful answer to very large questions with an unknown but large number of variables.” So much yet to discover…

  • Ron S July 22, 2007, 16:46

    I don’t see why evolution should stop, or at least stop in such a way that intelligence doesn’t arise. Once life fills an ecological niche there is competition and that competition among organisms is the arms race that selects for improvements in competitive ability. Intelligence is a late step in that process. It seems almost unavoidable unless interrupted. We even see that mass extinction events may promote diversity and further evolution rather than cause setbacks.

    I’m not convinced that ETI is rare if life is widespread.

  • Paul Dietz July 23, 2007, 11:50

    In what way is ‘Big Bang’ testable, Paul?

    The Big Bang is testable in the way all other scientific theories in astronomy is testable: by making predictions that match observations.

    Be aware that there is no other way known to explain the cosmic microwave background radiation without the existence of a hot, dense stage in the early universe. Various proposed alternatives (‘tired light’, ‘plasma universe’) simply don’t work. The CMBR is extraordinarily close to a perfect blackbody radiation bath, to better than five significant digits. This is better than we could make in the laboratory! This can only come in nature from an optically thick source in equilibrium with the radiation; it cannot come from some combination of non-thermal sources without manifold ludicrous coincidences.

  • Ronald July 23, 2007, 17:28

    Just one more thing with regard to the “starships by AD 500” issue, if you allow me: the original quotation as I read it by some astronomer (I think it was Carl Sagan, if I remember well) mentioned that, if it hadn’t been for the *political* victory of the (catholic?) church, we would already have been on our way to the stars by now. Puts it in a slightly ‘milder’ perspective.

  • Theo Stauffer July 23, 2007, 19:04

    HI all, my first post on this very interesting site. I just wanted to add that I think that the answer to life and advanced life in the universe is probably just as subject to chance as anything else out there. The problem is that, at the moment, we have a sample size of exactly one. But if we take our single sample as offering up some clues to what life may need in the universe, we might give ourselves a slightly better picture. There is the possiblity that the moon has been critical in acting as a tidal motor of life on earth. If the moon is the deciding factor, for instance, then life might be very rare indeed.

    Once started, however, life seems to be almost unstopable. Life has certainly been extremely hardy on earth and has persevered through numerous cataclysmic events. However, as far as we know, we are the only species on earth that ever developed advanced toolmaking abilities, perhaps the one feature that really defines our civilisation. It also seems, from our current viewpoint, as if this feature is not one that has developed numerous times in parallel as is the case with eyes, walking, flying. swimming etc. We have no examples of past species using advanced tools but then dying off.

    I personally suspect that tool making and using abilities need some kind of evolutionary push or factor to be succesful (hands, for example), that gives that mutation a life or death advantage over its competitors (weapons, clothes, fire etc), one that is fairly rare, or else we would have had many more competitors on earth.

    This probably applies to life elsewhere as well. IF the physical circumstances are right, it seems probable that life will develop, but the chances that advanced toolmaking life will develop might be astonishing small, and, as someone said above, there might be only a tiny sample of advanced civilisations in the universe, and we may very well be amongst the older ones.

  • Administrator July 23, 2007, 19:58

    You make good points, Theo, especially about life’s apparent unstoppability. The extraordinary places we keep discovering new life forms never ceases to amaze me, and leads many of us to think we will indeed find life elsewhere in our own Solar System, not to mention what may exist around other stars.

  • reader July 24, 2007, 23:04

    There doesn’t seem to be any real “reasoning” here at all. The assumption and the conclusion are the same.

    1. For some X (e.g. agriculture, electricity, space travel) SUPPOSE that we are closer to the middle of X than the beginning.
    2. THEN the end may not be as far away as we might have thought it was!

    Calling this the “Copernican principle” seems backward. Copernicus’ innovation placed us farther away from the middle, the center, not closer to it.

  • ljk August 1, 2007, 10:54

    “Why the Moon? Human survival!” by Robert Shapiro at


  • gavin immerson November 20, 2008, 6:57

    The quick answer to “Whither homo sapiens?” may indeed be “42” but the data trend is to nowhere, fast.

    However, excepting the (low level) background anthro-centric mythology, there are some useful ideas here, coherently argued, a rare thing on the “..tubes of the internets.”

    Turns out that pesky “Y2K Problem” is embedded in more than just our hard-drives and we all get plenty of remedial spam on that issue.

    There may, indeed be “Klingons on the starboard bow.” but more + more “It’s life Jim, but not as we know it.”

    Cheers from the North Woods, g