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Thread: What do you think is the most likely explanation for the Fermi paradox?

  1. #301
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    Came across this interesting paper that looks at the background assumptions many people make when thinking about SETI and the Fermi Paradox. Will step on toes but worth the read whether one agrees or disagrees with it.

    https://arxiv.org/pdf/1708.05318.pdf

    Visions of Human Futures in Space and SETI

    Jason T Wright, Michael P. Oman-Reagan (Submitted on 17 Aug 2017 (v1), last revised 20 Aug 2017 (this version, v2))

    We discuss how visions for the futures of humanity in space and SETI are intertwined, and are shaped by prior work in the fields and by science fiction. This appears in the language used in the fields, and in the sometimes implicit assumptions made in discussions of them. We give examples from articulations of the so-called Fermi Paradox, discussions of the settlement of the Solar System (in the near future) and the Galaxy (in the far future), and METI. We argue that science fiction, especially the campy variety, is a significant contributor to the "giggle factor" that hinders serious discussion and funding for SETI and Solar System settlement projects. We argue that humanity's long-term future in space will be shaped by our short-term visions for who goes there and how. Because of the way they entered the fields, we recommend avoiding the term "colony" and its cognates when discussing the settlement of space, as well as other terms with similar pedigrees. We offer examples of science fiction and other writing that broaden and challenge our visions of human futures in space and SETI. In an appendix, we use an analogy with the well-funded and relatively uncontroversial searches for the dark matter particle to argue that SETI's lack of funding in the national science portfolio is primarily a problem of perception, not inherent merit.

  2. #302
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    Quote Originally Posted by Roger E. Moore View Post
    SETI's lack of funding in the national science portfolio is primarily a problem of perception, not inherent merit.
    The same is true of almost anything related to space except satellites. And for that matter, almost anything ecological or climate related, "pure" science, or indeed beneficial to humans in any way other than in business; if it can't make money or war, it's not taken seriously.

    Don't mind me, I'm in a bad mood today.
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  3. #303
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    Quote Originally Posted by alromario View Post
    There is no paradox, and I expect first contact will be much less rewarding than we could ever believe. Joke, Iím sure it will go well.
    I'd predict that first contact (if and when it comes) it will be a gradual process. Indirect evidence becoming stronger until we're almost certain that a particular planet or system is inhabited by smart beings, but we'll still know nothing much about what they are like... It will be like Galileo's discovery of the 4 biggest moons of Jupiter. He didn't know anything about them except how bright they are and how they orbit, and it was centuries until anyone found out more...

  4. #304
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    Quote Originally Posted by Colin Robinson View Post
    I'd predict that first contact (if and when it comes) it will be a gradual process. Indirect evidence becoming stronger until we're almost certain that a particular planet or system is inhabited by smart beings, but we'll still know nothing much about what they are like... It will be like Galileo's discovery of the 4 biggest moons of Jupiter. He didn't know anything about them except how bright they are and how they orbit, and it was centuries until anyone found out more...
    I think if we get reasonably clear evidence of ETI somewhere, current humanity will attempt to send a signal of some kind to them if possible.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    I think if we get reasonably clear evidence of ETI somewhere, current humanity will attempt to send a signal of some kind to them if possible.
    Perhaps we would, although there would inevitably be concerns about dangers.

    Sending radio signals would certainly be easier than trying to develop an interstellar space probe, and arguably safer too. Throwing a fast-moving object at them could be interpreted as a hostile act...

    But a program of passive long-distance observation would be safer than either a signal or a space probe.

    If we did send them a signal, the light-speed factor would mean a serious wait for any reply they might send...

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    Quote Originally Posted by Colin Robinson View Post
    Perhaps we would, although there would inevitably be concerns about dangers.

    Sending radio signals would certainly be easier than trying to develop an interstellar space probe, and arguably safer too. Throwing a fast-moving object at them could be interpreted as a hostile act...

    But a program of passive long-distance observation would be safer than either a signal or a space probe.

    If we did send them a signal, the light-speed factor would mean a serious wait for any reply they might send...
    I doubt safety would be a major concern. If we can see them, and they have any capacity to actually reach us, then they can almost certainly already see us by then.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    I doubt safety would be a major concern. If we can see them, and they have any capacity to actually reach us, then they can almost certainly already see us by then.
    Another reason to suppose that we probably will send out a signal is that many countries would have the capability to do so, and it's hard to stop something from happening when many people can do it. There would have to be a consensus to stop it--absent such a consensus, it could easily happen.
    As above, so below

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    Quote Originally Posted by Jens View Post
    Another reason to suppose that we probably will send out a signal is that many countries would have the capability to do so, and it's hard to stop something from happening when many people can do it. There would have to be a consensus to stop it--absent such a consensus, it could easily happen.
    And if we are close enough the signal is already sent and possibly received, so to speak. If they are already advanced enough to detect even the faintest of signals and are looking then they might already have found us before we find them.

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    Maybe if they are nearby, THEY are not sending signals because they're afraid of US. And TBF we are a pretty scary bunch.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by alromario View Post
    There is no paradox,
    This is pretty much my attitude.

    I saw a show once where, to demonstrate the flaws in this "paradox", the host laid out everything at his home for a lobster dinner... except the lobster. Boiling water, drawn butter, nutcracker, etc. He called from his doorway, "Here lobsters!" When no lobster appeared, he opined, "If lobsters exist, where are they? It's a paradox!"
    Last edited by Noclevername; 2019-May-23 at 12:22 AM.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Even if a lobster were on the table to be seen by eye witnesses it'll still need to be DNA tested to be certain it's a real lobster.

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    Quote Originally Posted by Spacedude View Post
    Even if a lobster were on the table to be seen by eye witnesses it'll still need to be DNA tested to be certain it's a real lobster.
    I'm trying not to imagine this happening in a seafood restaurant, the waiters in a corner watching the DNA testing after they've brought the lobster.

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    Quote Originally Posted by Spacedude View Post
    Even if a lobster were on the table to be seen by eye witnesses it'll still need to be DNA tested to be certain it's a real lobster.
    I volunteer to do a taste test. I'm willing to take that risk.

    There's some question as to whether a civilization would go in person, or send Von Neumann probes; It may be both at once, if they are largely an AI or uploaded mind/society of minds. There could (odds unknown) be the ancient remains of an alien machine sitting somewhere undetected in our Solar System, millions or billions of years old. It did its job, retired, and died.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    The aliens we meet might not be representative of their kind as a whole. They might be outcasts, rebels, part of a secret group, etc.

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    Quote Originally Posted by Roger E. Moore View Post
    The aliens we meet might not be representative of their kind as a whole. They might be outcasts, rebels, part of a secret group, etc.
    We'd be hard pressed to find a human who is typical of our whole species. I would expect other intelligences to be similarly varied. No Star Trek monocultures here!
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  16. #316
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    Quote Originally Posted by Noclevername View Post
    This is pretty much my attitude.

    I saw a show once where, to demonstrate the flaws in this "paradox", the host laid out everything at his home for a lobster dinner... except the lobster. Boiling water, drawn butter, nutcracker, etc. He called from his doorway, "Here lobsters!" When no lobster appeared, he opined, "If lobsters exist, where are they? It's a paradox!"
    If a race of intelligent lobster-like ETs had arisen elsewhere in the galaxy say 3 billion years ago, we would by now be living in the Lobster Galactic Civilisation.

    Perhaps we are but are too dumb to realise it?

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    Quote Originally Posted by kzb View Post
    If a race of intelligent lobster-like ETs had arisen elsewhere in the galaxy say 3 billion years ago, we would by now be living in the Lobster Galactic Civilisation.
    Unless they fell, or died, or were non-expansive, or not expansive enough to cover the whole galaxy, or just non-intrusive.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    Unless they fell, or died, or were non-expansive, or not expansive enough to cover the whole galaxy, or just non-intrusive.
    But we've been into that.

    Principle of mediocrity coupled with the fact there wouldn't be just one race of lobsters over 3 billion years, there would be many.

    Even if some of them had the properties you describe, some would not.

    Another reason is the "Bleak Future" argument. Not particularly logical BTW, more like, "be careful of what you wish for".

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    Quote Originally Posted by kzb View Post
    But we've been into that.

    Principle of mediocrity coupled with the fact there wouldn't be just one race of lobsters over 3 billion years, there would be many.

    Even if some of them had the properties you describe, some would not.

    Another reason is the "Bleak Future" argument. Not particularly logical BTW, more like, "be careful of what you wish for".
    And I've already told you what the "principle" of mediocrity means in the real world... Nada. Zilch. Zero.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Based on our observations so far, the Universe is infinitely varied. IMO there is no such thing as mediocrity; it's all different, all unique.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by kzb View Post
    Another reason is the "Bleak Future" argument. Not particularly logical BTW, more like, "be careful of what you wish for".
    It seems like those scenarios have some merit; we are passing through existentially dangerous times. But, as with origins of life and intelligence, it's all about playing the odds. We might very well muddle through, and if we can survive these dark days then so could another species.

    ADDED: But it won't be easy; maybe the number of civilizations that make it through their industrial age intact is low.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by kzb View Post
    But we've been into that.

    Principle of mediocrity coupled with the fact there wouldn't be just one race of lobsters over 3 billion years, there would be many.

    Even if some of them had the properties you describe, some would not.
    How does the principle of mediocrity apply here?

    As I understand it, the principle of mediocrity says it's unlikely (though not impossible) that we humans are the smartest critters in the universe.

    IF we humans had colonised other star systems, then the principle of mediocrity would imply that other species have likely done some interstellar colonising also.

    But we haven't...
    Last edited by Colin Robinson; 2019-May-25 at 12:22 AM.

  23. #323
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    Many stars are far older than ours. It stars play host to inhabited planets, and civilizations, some of these cultures will probably also be much older than ours. Given what we know of stellar evolution, there would presumably be a continuum of technical ability in the various civilizations, from less advanced that we are to very much more advanced. Our failure to (yet) explore the galaxy simply suggests that we happen to stand rather low in the continuum of technical development.

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    Quote Originally Posted by Ross 54 View Post
    Many stars are far older than ours. It stars play host to inhabited planets, and civilizations, some of these cultures will probably also be much older than ours. Given what we know of stellar evolution, there would presumably be a continuum of technical ability in the various civilizations, from less advanced that we are to very much more advanced. Our failure to (yet) explore the galaxy simply suggests that we happen to stand rather low in the continuum of technical development.
    True, but we can only speculate on what a truly advanced civilization would be like, what would motivate them, and ultimately what they would do. And that's for the descendants of us humans! We're now on the verge of being able to genetically engineer and/or cyborgize ourselves. Would we even recognize our kin in 100,000 years? A million? Post-humans will likely become as alien as ET and as wildly varied and speciated as any animals over long time scales. Will they even be interested in the outside world, let alone motivated to spread their seed to fill all available space? Advanced cultures might be inherently virtual or inward-looking. Colonization could be a young species' game; play for a while, then move on to more important activities as you grow up.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    As speculations go, one founded on a behavior known to exist from a great many observed examples, such as territorial expansion, seems the most persuasive. This has occurred over a very long period of time, in a highly varied assortment of a great many species. It also has clear, and seemingly well understood evolutionary advantages.

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    Quote Originally Posted by Ross 54 View Post
    As speculations go, one founded on a behavior known to exist from a great many observed examples, such as territorial expansion, seems the most persuasive. This has occurred over a very long period of time, in a highly varied assortment of a great many species. It also has clear, and seemingly well understood evolutionary advantages.
    In naturally evolved species, on a planet, all from the same common ancestry, yes.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Ross 54 View Post
    As speculations go, one founded on a behavior known to exist from a great many observed examples, such as territorial expansion, seems the most persuasive. This has occurred over a very long period of time, in a highly varied assortment of a great many species. It also has clear, and seemingly well understood evolutionary advantages.
    In fact, like most things in evolution, spreading out has disadvantages as well as advantages.

    Here's a quote from the Wikipedia page Biological dispersal:

    "There are also a number of costs associated with dispersal, which can be thought of in terms of four main currencies: energy, risk, time and opportunity.[2] Energetic costs include the extra energy required to move as well as energetic investment in movement machinery (e.g. wings). Risks include increased injury and mortality during dispersal and the possibility of settling in an unfavorable environment. Time spent dispersing is time that often cannot be spent on other activities such as growth and reproduction."

    That's why living things do not spend all their time and energy boldly going where no member of their species has gone before.

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    Quote Originally Posted by Ross 54 View Post
    Our failure to (yet) explore the galaxy simply suggests that we happen to stand rather low in the continuum of technical development.
    I'm also not sure that we can make the assumption that we are not approaching a limit to what science can do, and that there will not be so many civilizations far beyond us. I know it is natural to assume that technical progress just goes on indefinitely, but since it is constrained by physical laws, we may also bump up against what we can achieve. I'm not saying that that is true, just that it is one of the possibilities.
    As above, so below

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    Quote Originally Posted by Jens View Post
    I'm also not sure that we can make the assumption that we are not approaching a limit to what science can do, and that there will not be so many civilizations far beyond us. I know it is natural to assume that technical progress just goes on indefinitely, but since it is constrained by physical laws, we may also bump up against what we can achieve. I'm not saying that that is true, just that it is one of the possibilities.
    A grim prospect! Still, we ourselves are a long way away from that.

    One thought is, it may not be possible to have a net power generating fusion reaction outside the conditions of a Sun. That would throw some cold water on a lot of interstellar travel plans.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    One thought is, it may not be possible to have a net power generating fusion reaction outside the conditions of a Sun. That would throw some cold water on a lot of interstellar travel plans.
    I expect it would be more complicated than that, but I agree something like that could be an issue. I've thought about that issue in terms of power sources for interstellar ships or other purposes where you want long term energy sources and how there might be long term resource limitations, as well as long term maintenance issues.

    Let's start with fission, where you essentially need uranium or thorium. Unlike chemicals that can be recycled, long term (many thousands of years) economic sources for these materials could be used up, especially if large amounts were needed for things like large generation ships, other advanced spacecraft and industrial processes not close to a star. There might also be issues keeping reactors subject to radiation damage running over periods of multiple centuries (mostly, I think, due to transmutation caused be neutrons). Also, worlds around more metal poor stars may be poor sources for these elements.

    Then we get to fusion. The easiest is the deuterium/tritium reaction. I expect we'll be able to build DT power reactors as long as we scale them up large enough (Tokamak is looking pretty good). But tritium has a 12 year half life so must be bred from lithium for any long term power system. Also, like uranium and thorium, the supplies of deuterium and lithium are relatively limited, especially lithium.

    And there is the reactor maintenance issue here: Most of the energy comes in the form of high energy neutrons, the plasma can erode the walls, and a fusion reactor is inherently more complex than a fission reactor (electromagnets and so forth).

    Then there is the pure D-D reactor (just deuterium). That's a much harder reaction than D-T, so harder to say how practical that would be today. At the least, probably it would require an even larger reactor than D-T. It's possible that deuterium could be mined from gas giants, but then we're jumping into another area of speculative technology. And even if it were to become technically viable, economic viability would also be an issue.

    Then you get into all sorts of other options, like deuterium-helium 3, or some other things, some with some advantages (fewer neutrons) but typically hard reactions to run in a reactor and their own resource limitation issues.

    Where it gets really hard is if you want to just use plain hydrogen. The sun's proton-proton chain requires multiple steps, is really difficult and the energy density is very low, so not that useful for a spacecraft. The CNO cycle is better from an energy density standpoint, but is also very difficult. (You see CNO in more massive stars than the sun).

    So I think it's very possible that fusion could be important as a temporary phase for civilization, then largely go out of favor because of resource limitations and practical use issues.

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