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Brane Worlds, the Subanthropic Principle and the Undetectability Conjecture

  1. Sep 27, 2004 #1
    http://www.arxiv.org/abs/physics/0308078

    Could we belong to a non-aggressive advanced civilization, which protects earth? And does the general population suffer from the crown of creation syndrome?
     
  2. jcsd
  3. Sep 27, 2004 #2

    Garth

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    There is what I call in a lecture the "Moral Imperative of Drake's Equation". The most significant factor in that equation is the estimate of how long an advanced technological society will last once evolved. We discovered radio telescopes (the SETI requirement for an advanced civilization) pretty much simultaneously with the atomic bomb; so how long do you expect us to last?
    The conjecture then is that a relatively large number of E.T civilizations evolve of which many destroy themselves in short time. Those that survive the technology crisis when they not only develop the knowledge of these advanced technologies but also the wisdom to handle them, are the ones that "deserve to survive".
    Hence we may be in a community of such E.T. civilizations but are in quarantine until we prove ourselves fit enough to survive long enough to be granted membership of that community.
    Just a thought, Garth
     
  4. Sep 27, 2004 #3
    Thanks Garth!

    Ok, given that nuclear weapons pose a risk to the human race, we’re not exactly seeing them being used in warfare. Fanatical dictators who gain possession or develop nuclear capabilities are under greater pressure to disarm. Also we’re aware of the dangers associated with nuclear weapons, so even though we may be immature on a galactic scale, we’re not that stupid to blow ourselves up.

    Even if we aren’t in quarantine or alone, I would see us or any other civilization under the same circumstances, having a very favorable chance at survival. But that’s just my opinion.

    On the other hand if we are in quarantine to increase survival rate, then it would explain all the UFO activity around military installations. :smile:
     
  5. Sep 27, 2004 #4

    Garth

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    Extraordinary claims demand extraordinary evidence - although the UFO hypothesis is not illogical given what we have just said, I do not find there is substantiated evidence of their existence. I find the 'X Files' conspiracy hypothesis incredible after some 60 years and the break up of the cold war, somebody would have come clean!

    By the way Vast, quote: "Also we’re aware of the dangers associated with nuclear weapons, so even though we may be immature on a galactic scale, we’re not that stupid to blow ourselves up. "
    I find your faith in our future security against the threat of nuclear devastation touching, but I wouldn't count on it!

    Garth
     
    Last edited: Sep 28, 2004
  6. Sep 27, 2004 #5
    Something that I find quite amazing is our apparent lack of knowledge to what’s really out there. In the same way the mountain gorilla doesn’t know the larger world it lives in, we humans seem to be only just opening our eyes to the place we inhabit.

    Who knows, perhaps we’ll discover a whole host of planets harboring life in the next few decades? Maybe its not so bad that we’re alone in our little region of the cosmos, I’m sure at any rate that the universe didn’t develop to form just one intelligent civilization in one average size galaxy in some small corner of the universe.

    Has there been any documentation of a civilization destroying themselves in the past? Apart from natural disasters that is? Perhaps we haven’t had the means to destroy ourselves like we do today, be it with nuclear weapons or global viruses. So perhaps to guard against such an outcome we must prevent such a thing from happening. I guess that’s why I’m optimistic.
     
  7. Sep 27, 2004 #6

    Nereid

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    First, there have been only a few independent civilizations in the history of the mammal, Homo sap. (though it depends somewhat on what you mean by 'civilization'), and those which are no longer with us - e.g. Incas, Aztecs, Harappa - were all 'destroyed' by the actions of other people.

    Perhaps more interesting is what happened when a group of humans with all kinds of 'advanced' capabilities (e.g. agriculture, metal-working for tools) got isolated in a smallish area with the resources to support only a small population (using the technologies they had at the time) ... they lost the capabilities that were beyond what the region could support! For example, abandoning agriculture to return to hunting & gathering; abandoning metal-working to return to stone and bone.
     
  8. Sep 27, 2004 #7

    selfAdjoint

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    Something like this happened to the polynesians who colonized Easter Island. This was at the limit of their navigation capabilities and once the colonists got there, they couldn't get to anywhere else. But the island didn't support the higher level culture of polynesia (as for example in the Maoris and Hawaiians) and gradually they lost it. They wound up as a primitive stone age culture.
     
  9. Sep 27, 2004 #8

    Chronos

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    The are several examples of new world societies that appear to have disappeared with few clues as to the cause; Cahoks, Anasazi, and Teotihuacans to name a few. It would be fair to say a number of ancient and not so ancient civilizations self-destructed because of despotism, incompentent leadership, stagnation or disasters which led to desertion, disolution or conquest.
     
  10. Sep 27, 2004 #9

    turbo

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    Not to mention establishing outposts with insufficient genetic variability and/or isolated enough to inhibit cross-pollinating effects like trade, infusion of new ideas, etc. Another disastrous thing is disease and/or harsh conditions that kill off the weaker members (usually the very young and the very old). Losing most of your children means your group's future reproductive viability is compromised, and losing the older generations means that the collective "memory" of the group is crippled. In cultures where the oral tradition is strongest, this can be the most devastating loss of all.
     
  11. Sep 27, 2004 #10

    Nereid

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    There's no lack of data concerning small groups - hunter-gatherer bands, nomadic tribes, pre-agricultural chiefdoms, even proto-states - that disappeared or lost their 'advanced' capabilities, and many may have done so for reasons other than contact with other groups.

    However, when it comes to 'civilizations' - crudely, centralised states with strata/hierarchies which were able to mobilise lots of labour for 'public' projects such as irrigation, armies, temple-building - I doubt there are any which disappeared other than primarily through contact with other groups of humans (in many cases of course, the contact was slaughter and enslavement).
     
  12. Sep 27, 2004 #11
    The most significant factor in the Drake equation pointed out by Garth is how long an advanced technological society will last? So in regards to this factor, the only civilizations important to the discussion would be those existing within the last fifty thousand years or so.

    While a few independent societies have become isolated and as a result lost touch with the outside world, this hasn’t been a major problem for the evolution of the human population at large.

    Likewise, one civilization intent on the destruction of another has been purely to dominate. Technological escalation in war has been an important factor in destroying other societies, as well as strategic planning. So wouldn’t it be reasonable to say that competition hasn’t inhibited the overall population’s technological growth?

    Yes, it’s possible that the technology we possess has the potential to destroy all of mankind, but in order to do so IMO, a technological civilization needs to have the desire to destroy itself, not merely capabilities spelling certain doom. The assumption that every advanced civilization is doomed to destroy itself, is one I find Frank Drake constructed from personal views about the destructive nature of humans, not taking into account the role war plays on the evolution of any species.

    Perhaps the Drake equation needs a little revision?
     
  13. Sep 28, 2004 #12

    Chronos

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    There are a number of reasons, other than self-destruction, that could doom a civilization. Their star could could destablize, a neighboring star could go nova, or supernova, asteroid collisions [re: earth], geological instability [massive earthquakes or volcanic explosions], exhaustion of critical resources, pandemics, etc. The universe is a hostile environment.
     
  14. Sep 28, 2004 #13
    Chronos I’m aware of the other potential disaster that any living species is faced with, but the main factor I was addressing was the assumption that once a civilization becomes technologically advanced it faces yet another challenge, one that the Drake equation implies we’ll carelessly wipe ourselves out. Given that humans are wreakless in nature there’s good reason for believing this.

    The point I’m trying to make however is that although humans appear to be a senseless, destructive species at the best of times, leading to the extermination of aboriginals cultures, and even most other species that we share the world with, there also appears to be a growing realization that killing other cultures just because their primitive, or raping the earth of its resources is inevitably going to be harmful to ourselves in the long run.

    I’m not saying the Drake equation hasn’t taken into consideration some of the likely causes of extinction, but simply that the assumption that an advanced technological society will wipe itself out is not something I particularly find very probable. Therefore this part of the equation IMO needs to be revised.

    My ideas probably originate from this book.
     
  15. Sep 28, 2004 #14

    Garth

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    Whether or not Drake himself considered "that every advanced civilization is doomed to destroy itself" does not affect his equation, which stands on its own as a very basic and robust estimation, or 'guesstimation' of the number of ET civilizations that may be extant. If we restrict ourselves only to those civilizations with which we may make contact, who have radio telescopes/lasers or some equivalent inter-stellar communication device, which I label 'SETI civilizations', then we have the following wild estimate.

    1. Homo sapiens has existed < 10^6 yrs, our civilization < 10^4 yrs, our own SETI technological civilization < 10^2 yrs. The age of the galaxy is ~ 10^10 yrs. So our window of opportunity in which we may communicate with ETs is at present 10^(-8) of the age of the galaxy.

    But
    2. The average rate of star formation 10/yr.
    3. The fraction of stars with planets ~ 0.1 - 0.01 or higher.
    4. Systems with biological niches capable of supporting life??? 10^(-3) ??
    5. Biological niches that produce life ~0.1?? (life appeared on Earth almost 'as soon as' it was capable of supporting it).
    6. The fraction of life bearing planets that evolve technological species - who knows?? But it happened on Earth after about 1/2 of the present age of the galaxy - so perhaps around 0.5 -> 0.1?? But it could be much much less; the probability of our existence could be merely a selection effect!

    The product of these other 'improbabilities' (points 2 - 6) is an order of magnitude or so greater than the fraction of the galactic lifetime we have had SETI technology that is why I have said the lifetime of a SETI civilization is the most significant factor in whether they are extant or not.

    As a consequence of points 2 -6, multiplying them together, our galaxy may be producing SETI civilizations at the rate of about 10^(-6)/yr.

    For one SETI civilization to be around today it would have to survive for about 10^6 yrs on average. If however such a civilization lasts for an astronomical rather than human timescale, say for 10^9 years then there may be 10^3 of them out there. These would be separated by about 500 parsecs as a very rough average.

    But of course I could be completely wrong!!

    So after less than 10^2 years how are we doing?

    Garth
     
    Last edited: Sep 28, 2004
  16. Sep 29, 2004 #15
    Sorry to change the discussion a little Garth, but I just want to present an observation, also addressing this question of "where is everybody?"

    A possible reason we may not find ourselves immersed in a larger civilization is that our galaxy is relatively small. The Milky Way Galaxy isn’t situated in a very large cluster, and therefore hasn’t grown to be very big. However a lot of other galaxies have, especially those found in the large scale structure regions. These regions are often packet with clusters of hundreds or thousands of galaxies which surround enormous cD galaxies as large as 6 million light year in diameter.

    The inner regions of the Milky Way Galaxy is mostly comprised of stable star systems, those stars that are relatively long lived, and towards the outer edge we find stars that are usually short lived supergiants. We also see large clusters of stars in our galaxy, which may be remnants of other galaxies it has consumed in the past.

    So assuming larger galaxies have the same properties with stable star system towards their centers, they should allow the production of more planets with life, therefore if the circumstances were different and we were situated in one of these giant galaxies we should find ourselves immersed within a larger civilization. A. because there would be a larger collection of stable star systems, and B. because many more mergers make interstellar travel to other advanced civilizations more likely.
     
  17. Sep 29, 2004 #16

    Garth

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    I think our galaxy is big enough, of the order of 10^11 stars.

    We are thinking of G and K type stars in the main which are plentiful in the galactic disc, although as they are not the brightest of stars they are under represented on a star field plate.

    My estimate of 500 parsecs to the nearest E.T. was based on, amongst other things, them lasting for 10^9 years which may be wildly optimistic. An absolute maximum of 10^8 years, like the dinosaurs, may be more reasonable. In which case our E.T. neighbour will be of the order 10^3 parsecs away.

    This itself will act as a natural quarantine, without any conscious embargoes. The Fermi paradox (where are they?) is optimistic about the possibility of inter-stellar travel. It may never be possible for living creatures, the energy costs and time of travel are just too high; except that is for a "message in a bottle" like the Voyagers,

    Garth
     
  18. Sep 29, 2004 #17

    selfAdjoint

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    Notice that no one dinosaur species lasted 10^8 years. Biologists have stated the average lifetime of a species as 10^6 years; what does that do to your distance?
     
  19. Sep 29, 2004 #18

    Garth

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    Thank you - it is only a 'guesstimate' of the absolute maximum lifetime. If the rate of SETI civilization genesis is 10^(-6)/ yr and the maximum lifetime of such a civilization that has overcome the technology crisis is 10^6 yr then the chances are we are alone in the Milky Way galaxy - we are the only one! :cry:
    That would explain the Fermi paradox quite nicely!
    Garth
     
  20. Sep 29, 2004 #19
    I may have misunderstood what both of you have been saying, as it seems both of you are speculating how long an advanced technological civilization will last? Using the average lifetime of 10^6 years for a species is all well and good for civilizations that remain earth bound, but we’re only a couple hundred years away from beginning the full colonization of the solar system. Therefore assuming a technological civilization passes the so called technology crisis, there should be no restrictions to how long it can last. The lifetime of a space based civilization is essentially unlimited!

    OK, let me have it! :biggrin:
     
  21. Sep 30, 2004 #20

    Garth

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    As I have said all along Drake's equation is only a "guesstimate"!
    Garth
     
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