Space vs. Time Allies

Consider two possible civilizations, stretched either across time or space:

  • Time: A mere hundred thousand people live sustainably for a billion generations before finally going extinct.
  • Space: A trillion people spread across a thousand planets live for only a hundred generations, then go extinct.

Even though both civilizations support the same total number of lives, most observers probably find the time-stretched civilization more admirable and morally worthy. (more)

Our distant ancestors struggled against nature and other species, but competed most directly for mates and resources with others in their species, especially others in the same generation. More distant generations, like grandparents or grandkids, tended more to be allies in their efforts to promote their genes and culture. Because of this, Katja and I suggested, humans evolved intuitions that see time-stretched civilizations as more full of comforting allies, and hence more worthy, than space-stretched civilizations.

Modern economies, however, differ in many important ways from the forager bands where these intuitions evolved. So let us compare the relative promise of time-stretched versus space-stretched modern economies with similar total numbers of people.

  • Scale Economies – Spatially large civilizations can specialize more in the production of goods and services, and take advantages of economies of scale, to get more of everything. Temporally large civilizations, in contrast, can only take advantage of scale economies for extremely durable goods like music. This issue favors spatial stretching.
  • Dependence Fragility – The more that the parts of a civilization depend on one another, the more that damage to one part can put the whole at risk. In a time stretched civilization a very bad outcome for any one generation risks the destruction of all future generations. It is a long chain of dependence that is only as strong as its weakest link. In contrast, a space stretched civilization allows for more redundant and parallel dependence paths. It can be more like a net that holds even when many of its strands are broken. This issue favors spatial stretching.
  • Innovation – A finite speed of light imposes delays on how fast innovations developed in one part of a spatially separated civilization can be used elsewhere.  [Added 8a: parallel innovation attempts also make info delays.] The more that a civilization is time-stretched, as opposed to space-stretched, the smaller are such delays. Our civilization is now compact enough that such delays are only a minor issue. This will also cease to be an issue when innovation has ended, i.e., when we have basically discovered all that is worth knowing. This issue favors time-stretching, but only during a (perhaps short) innovation era and only for very spatially stretched civilizations.

Overall, for similar numbers of total people, modestly spatially-stretched civilizations seem more promising. Thus in contrast to our evolved intuition that temporal associates are our allies while spatial associates are our rivals, spatial associates seem to actually be more useful, and hence are more naturally our allies. Beware relying on ancient evolved intuitions.

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  • Prakash

    The scale economies and dependence fragility points can be used separately, but not together as they mildly contradict each other.

    If the spacially stretched civilization has a supply chain that stretches from end to another, then they can take advantage of specialization and economies of scale. However, this also creates a dependency and the consequent fragility follows. eg. The slowdown in semiconductor and automobile industries due to the japanese tsunami. The interconnectivity of world markets results in crises spreading from end to another, no country is spared.

    Is it possible that I’ve mistaken your point and you’re thinking of relatively autarkic worlds, part of a larger civilization only in terms of origin and little else?

  • Larifari

    Finite speed of light is not the main limiting factor in innovation. Much more important is the fact that innovation is not easily parallelized, i.e. throwing twice as many people at a problem does not solve it twice as fast. So time-stretched civilizations are even more favored.

  • http://hanson.gmu.edu Robin Hanson

    Prakash, yes there is a tradeoff between specialization and interdependency. Still, more favorable trades can be made in a spatially stretched civ.

    Larifari, the main difference between parallel and serial innovation attempts is the fact that in the parallel case you don’t get as many signals about some attempts before trying other attempts.

  • http://rwcg.wordpress.com/ Sonic Charmer

    Everything here seems stated backwards to me in this attempt to shoehorn it all into the ‘foragers’ thing.

    Scale economies don’t automatically scale with the (geometric) ‘size’ of a civilization. There are a large number of mosquitoes, stretched the world over, but they don’t have a very good scale economy. There is also connectedness, knowledge, innovation, efficiency. The Time civilization – by virtue of its having lasted longer – can be assumed to have developed more of these things. Time is far more likely to have developed labor-saving robots that can do the work of 1000 men, for example. Space probably hasn’t had the time to do so.

    You say the Space civilization has less fragility due to redundancy and size, which may be a valid a priori assumption, but the problem is: empirically, it wasn’t less fragile. After all: it didn’t last nearly as long. You appear to be contradicting, or forgetting, your own hypothetical setup, which involved the Time civilization being ‘sustainable’ and Space going extinct after a relatively small number of generations.

    As Larifari says, innovation isn’t primarily limited by the speed of light. It’s linked to the growth of knowledge. I suppose you want an assumption that all else equal, Space and Time could grow the same amount of knowledge given the same number of people. I’m not sure that’s true. The outcomes of experiments, trial and errors, blind alleys, lucky guesses, etc. have to be waited on, observed, absorbed, and recorded. This completely favors Time even if both civilizations have the same number of people and even if speed of light/communication is infinite. Also – again – the empirical fact that Time lasts longer suggests that it achieved more in this area than did Space.

    Our ‘temporal intuition’, if you’re right that that’s what we have, seems completely correct to me.

  • nate

    “Spatially large civilizations can specialize more in the production of goods and services, and take advantages of economies of scale, to get more of everything. Temporally large civilizations, in contrast, can only take advantage of scale economies for extremely durable goods like music.”
    -While abstract ethical notions are difficult to account for in economic models, which civilization do you think have a better (poorly defined I know) culture, in terms of civil society and the liberal arts? Your example of music leads me to believe that while it could be the case that a spatially stretched civilization would have the best spaceships, but a time stretched civilization would have superior culture and institutions.

    P. S. I would also object to your statement here: “when we have basically discovered all that is worth knowing”. I could see the laws of physics being fully understood, but there are other areas of knowledge that seem to lack this kind of epistemological ceiling (mathematics being a well defined case of this). Additionally, even in the case of physics, it is one thing to understand the axioms and rules of inference of a system, and another to understand how they combine in complex ways. We might come to know the laws of nature completely, but still be surprised by materials science for example.

  • http://michaelkenny.blogspot.com Mike Kenny

    maybe we want to convince competitors to take the temporal approach, while we use the spatial approach. while they’re being modest, we’re expanding and overwhelm them.

    this might help to explain why the spatial approach seems the real temporal approach, while the temporal approach seems just a bad approach.

    it’s like cold war fears. we make an arms agreement and then worry our enemy is cheating while we’re not. fits with robin’s homo hypocritus.

    • http://rwcg.wordpress.com/ Sonic Charmer

      I would say it’s a mistake to speak of the societies as having consciously different spatial vs. temporal ‘approaches’. We are not told that. We are told only that Space is more numerous than Time and that Time lasts longer than Space. Empirically, this probably means that Time had the better overall ‘approach’, whatever that might mean.

      So Time didn’t get to be Time by ‘using the temporal approach’, they got to be Time because they did the sorts of things that help societies last a long time. Many of those things might correspond to what someone would consider a ‘spatial approach’.

      Indeed, I would say that consciously using a ‘temporal approach’ (fretting too much about ‘sustainability’, say) is probably not a good way to become a Time civilization. Not do I think a ‘spatial approach’ (spreading out as thinly and as quickly as possible??) would help you become a Space civilization, just a dead one or a splintered one.

  • Josh Burroughs

    Both civilizations are quite sub-optimal:

    How does a 1000-planet civilization manage to get itself wiped out after such a short period of time? They must be taking terribly unwarranted risks to enable their expansion.

    A civilization which can last for a billion *generations* obviously has considerable technological acumen (deflecting asteroids, building a replacement for their star, total-conversion energy supply, etc.); why not expand? The social strictures required to prevent humans from expanding over such a long time-period would most likely be quite unpleasant.

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