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

  1. #781
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    Quote Originally Posted by Selfsim View Post
    unconstrained, speculated so-called

    Could I ask a yes-or-no question? Simply put:

    Do you personally think it is plausible that some form of non-terrestrial life capable of being detected by us, could exist?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Selfsim View Post
    Many motives are considered 'valid' and that particular criteria, itself, is also unconstrained. How many of such criteria (and associated activities) do you think might be sufficient?
    "Whatever works" is my motto.


    Oh, and I don't recall ever having argued about stopping useful research .. rather, just recognise what useful returns it actually achieves, whilst noticing the irrelevance of the beliefs motivating it, when it comes to the actual returns of the research.
    Useful is as useful does. Many discoveries have been motivated by a wide range of desires or goals. Chemistry came from alchemy. (No, I'm not saying SETI is equal to Medieval searches for transmutation. Still, elemental transmutation is now recognized scientific fact; We just call it nucleosynthesis now.)
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Selfsim: I am content to disagree.
    Do good work. —Virgil Ivan "Gus" Grissom

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    Quote Originally Posted by Noclevername View Post
    Could I ask a yes-or-no question? Simply put:

    Do you personally think it is plausible that some form of non-terrestrial life capable of being detected by us, could exist?
    In the spirit of this particular thread: 'Maybe'.

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    Quote Originally Posted by Roger E. Moore View Post
    Selfsim: I am content to disagree.
    Ok .. no worries.

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    Drat and double drat, there were about 100 missing stars but they are more likely to be flaring red dwarfs or something. Well, it's a good start. The "5. Discussion" section is worth a careful read, liked it.

    https://arxiv.org/abs/1911.05068

    The Vanishing & Appearing Sources during a Century of Observations project: I. USNO objects missing in modern sky surveys and follow-up observations of a "missing star"
    Beatriz Villarroel, Johan Soodla, Sébastien Comerón, Lars Mattsson, Kristiaan Pelckmans, Martín López-Corredoira, Kevin Krisciunas, Eduardo Guerras, Oleg Kochukhov, Josefine Bergstedt, Bart Buelens, Rudolf E. Bär, Rubén Cubo, J. Emilio Enriquez, Alok C. Gupta, Iñigo Imaz, Torgny Karlsson, M. Almudena Prieto, Aleksey A. Shlyapnikov, Rafael S. de Souza, Irina B. Vavilova, Martin J. Ward
    (Submitted on 12 Nov 2019 (v1), last revised 21 Nov 2019 (this version, v2))

    In this paper we report the current status of a new research program. The primary goal of the "Vanishing & Appearing Sources during a Century of Observations" (VASCO) project is to search for vanishing and appearing sources using existing survey data to find examples of exceptional astrophysical transients. The implications of finding such objects extend from traditional astrophysics fields to the more exotic searches for evidence of technologically advanced civilizations. In this first paper we present new, deeper observations of the tentative candidate discovered by Villarroel et al. (2016). We then perform the first searches for vanishing objects throughout the sky by comparing 600 million objects from the US Naval Observatory Catalogue (USNO) B1.0 down to a limiting magnitude of ∼20−21 with the recent Pan-STARRS Data Release-1 (DR1) with a limiting magnitude of ∼23.4. We find about 150,000 preliminary candidates that do not have any Pan-STARRS counterpart within a 30 arcsec radius. We show that these objects are redder and have larger proper motions than typical USNO objects. We visually examine the images for a subset of about 24,000 candidates, superseding the 2016 study with a sample ten times larger. We find about ∼100 point sources visible in only one epoch in the red band of the USNO which may be of interest in searches for strong M dwarf flares, high-redshift supernovae or other catagories of unidentified red transients.

    QUOTE: One may wonder why a highly advanced Kardashev IIIII civilisation, capable of putting Dyson spheres around every star in a galaxy, would limit their effort to harness the energy of stars over such a giant volume as an entire galaxy. Indeed, an AGN occupies a much smaller space (as small as our Solar System), and has much more concentrated energy to offer. For example, the quasar 3C 273 has about 4 trillion times the luminosity of our Sun. Indeed, an AGN may be a significantly more effective target to build a Dyson sphere around. Many AGN (in particular obscured ones) naturally have a thick layer of dust dimming the central power source and giving off infrared emission. This dust is located at the sublimation radius. When an AGN is so obscured that hardly any photons leak through to excite the surrounding gas, we may not even detect the typical narrow emission lines that are the signature of an AGN.
    Last edited by Roger E. Moore; 2020-Jan-29 at 11:56 PM.
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    Quote Originally Posted by Noclevername View Post
    Could I ask a yes-or-no question? Simply put:

    Do you personally think it is plausible that some form of non-terrestrial life capable of being detected by us, could exist?
    Definitely it is plausible that primitive life exists and could be detected quite shortly. Personally I think it is only a matter of time before life is discovered on Mars, and plans to detect biosignatures on exoplanets seem well advanced.

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    Quote Originally Posted by Selfsim View Post
    In the spirit of this particular thread: 'Maybe'.

    So it may be. Answered.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    We are still very young; and very very backward. Our science is still primitive. We’ve not yet landed on another planet. We’ve just switched on our computers. The Universe is BIG. We are probably using primitive radio technology vs what the aliens may be using. And we’ve searched so very little. The answer to the Fermi Paradox; is that there is none; for we will discover evidence of technology within 10 years.

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    Quote Originally Posted by zebonaut View Post
    We are still very young; and very very backward. Our science is still primitive. We’ve not yet landed on another planet. We’ve just switched on our computers. The Universe is BIG. We are probably using primitive radio technology vs what the aliens may be using. And we’ve searched so very little. The answer to the Fermi Paradox; is that there is none; for we will discover evidence of technology within 10 years.
    All your statements are very plausible:
    The items I've underlined could possibly be true but we have no standard to compare to other than our own. It could turn out that so far, we are the most advanced life form in the universe.

    (my bold)
    I'd be amazed if we discovered technological life in such a short period (assuming there is some out there). I would expect, if anything, we are more likely to detect the signatures of some form of life based on the spectral analysis of the light emitted from the planets we have discovered that reside within the "Goldilocks" zones of their parent stars.
    Since the only evidence we have of life is here on Earth, the most common factor for life to exist appears to be liquid water. So based on this, the rocky planets discovered at just the right distance away from there parent star/s are likely to be the best candidates. If then the spectral light analysis reveals certain gases present within the planet's atmosphere (again assuming one exists), these gases could be the tell tale signs of some form of life.

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    Quote Originally Posted by zebonaut View Post
    We are still very young; and very very backward. Our science is still primitive. We’ve not yet landed on another planet. We’ve just switched on our computers. The Universe is BIG. We are probably using primitive radio technology vs what the aliens may be using. And we’ve searched so very little. The answer to the Fermi Paradox; is that there is none; for we will discover evidence of technology within 10 years.
    Welcome, Zebonaut. You had me up until the last 10 years.

    I think given the scale and vast number of unknowns involved, specific number predictions about finding Extra-Terrestrial Intelligence are futile. Especially with the search strategies we humans seem to commonly employ, limited more by budgets and low priority than by technical feasibility or physics. The "paradox" is, as you imply, on our end, not that of any potential ETI. We might find undisputed signs of intelligent life tomorrow, in ten thousand years, or never.

    Assume for a moment that there is actually a technologically advanced society of organic or post-organic beings that spreads colonies at the maximum rate suggested in this thread, putting out all kinds of clear and unmistakable radio signals in all directions... in a different Galactic super-cluster. We would never meet them or know about them no matter how loud and prolific they get. There is just too much time and space between us.

    Or, suppose ETI evolved next door in the Alpha Centauri system. But, they peaked and died off a million years before Homo Sapiens walked the Earth. Oops! Just missed 'em. And even if someday we can cross the vast distance to their system and set down on a planet there, we still might not recognize their technological artifacts unless they were both similar to our own, and survived the erosion of their world's surface.

    We might find life, yes, and that would be an enormously significant discovery in its own right. But other minds? We may have to resign ourselves to the thought that we will never come across sapient, sentient beings that we do not create ourselves. The odds of finding other "people", are literally incalculable.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    We haven't found them because we aren't funding SETI enough?

    https://www.bbc.com/news/science-environment-51223704

    ...Or we're looking in the wrong places? Try white dwarf stars.

    https://www.livescience.com/search-a...arf-stars.html
    Last edited by Roger E. Moore; 2020-Feb-15 at 01:23 AM. Reason: more
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    Breakthrough Listen has still found nothing. Keep searching. Very interesting survey set, though.

    https://scitechdaily.com/extraterres...m-seti-survey/
    Do good work. —Virgil Ivan "Gus" Grissom

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    Quote Originally Posted by Chuck View Post
    We should have conspiracy theorists analyze the data. They think outside the box.
    OK, I'll bite. Or are you serious? ... Ehh, I'll bite anyway. I just bought a book called " The day after Roswell" written by Col. Philip J. Corso, RIP. back in 97. I haven't gotten very far into it yet but he was in the army during WWII and worked for Army Intelligence later on.... says he saw a dead "alien" in transit to Patterson while at a Kansas army base in 1947. Later, in 1961 he was given command of one of the Pentagon's highly classified weapons development budgets and was made privy to the Govs big secret: the appropriation and dismantling of the Roswell UFO by the Army. Then, identifying many of those involved, Col. Corso reveals how a deep cover "council" officially poo pooed all UFO reports and had sent the goods to the Pentagon to analyze and attempt to integrate some of the artifacts into the military and private sector. He inherited a "Filing Cabinet" with some of the artifacts in 61 and spent the next three years dealing with it. There is NO PARADOX according to this....And quite honestly I'm not surprised they haven't landed on the White House Lawn. Not only may aliens exist but they may BE here. Now while this book may be fabricated and wholly or partly untrue.... he died the year after publishing it .... many other retired military (some on their death bed) have been coming forward lately and adding their testimony corroborating at least some of the narrative.... Food for thought..........
    Last edited by Grant Hatch; 2020-Feb-18 at 02:59 AM.

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    Quote Originally Posted by Grant Hatch View Post
    Col. Corso ... inherited a "Filing Cabinet" with some of the artifacts in 61 and spent the next three years dealing with it.
    Okay, I'll bite. Show us the filing cabinet and documents, then we'll talk.

    Ooo, okay, it doesn't exist anymore. No food for thought, then. Congrats to the colonel, but I've written fantasy & science fiction, too.
    Do good work. —Virgil Ivan "Gus" Grissom

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    Quote Originally Posted by Roger E. Moore View Post
    Okay, I'll bite. Show us the filing cabinet and documents, then we'll talk.

    Ooo, okay, it doesn't exist anymore. No food for thought, then. Congrats to the colonel, but I've written fantasy & science fiction, too.
    It Doesn't?? Dang, how did you find that out? Sources??

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    Can you show us the filling cabinet/documents as Roger requested? I’m not interested in unsupported claims. There is a lot of fiction in the ufo story business.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

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    Everyone, a reminder that this is Life In Space. If you want to discuss Conspiracy Theories there is a forum just for that. Not here.
    Never attribute to malice that which can be adequately explained by ignorance or stupidity.
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    If you won a professional prize on Earth, and were a population biologist, you might take a trip to Australia, to study the kangaroos, but you'd probably not have lunch with them, or engage them in discussions of global warming. Life forms with sufficient technological advantage to travel to Earth from great distances, over long times, might feel the same way.
    Makes you think about how some people treat animals. pete

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    Quote Originally Posted by trinitree88 View Post
    If you won a professional prize on Earth, and were a population biologist, you might take a trip to Australia, to study the kangaroos, but you'd probably not have lunch with them, or engage them in discussions of global warming. Life forms with sufficient technological advantage to travel to Earth from great distances, over long times, might feel the same way.
    Makes you think about how some people treat animals. pete
    I hear this a lot. I should think it would be clear to any "visiting intelligence" that we exhibit complex social behavior and have a high level of tangible technology. Why said "aliens" would have no interest in actually communicating with us, rather than sneaking around probing orifices or projecting blurry blobs in the sky makes no sense whatever.

    CJSF
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    Davy, Davy Crockett
    There's more than we were taught"

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    Quote Originally Posted by CJSF View Post
    I hear this a lot. I should think it would be clear to any "visiting intelligence" that we exhibit complex social behavior and have a high level of tangible technology. Why said "aliens" would have no interest in actually communicating with us, rather than sneaking around probing orifices or projecting blurry blobs in the sky makes no sense whatever.

    CJSF
    Maybe they judge superiority by land use, they'd think cattle were the dominant species. We're merely a side project.

    I'm only half joking. Maybe they wouldn't recognize our level of intelligence any more than we consider social insects our equals.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Why communicate with us when there is really no need? It shouldn't be too difficult for ETs to observe, monitor, and learn everything they'd ever want to know about us without having direct contact. Being stealthy has a lot of advantages, one of the most important may be not having to answer a lot of annoying Human questions.

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    It's possible for two things to be true at once. We could be under observation by ETI, and flying saucers could be delusions.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Paper just came out of interest here, perhaps. The equation parts are messed up but what can you do.

    https://arxiv.org/abs/2002.08194

    On the Likelihood of Observing Extragalactic Civilizations: Predictions from the Self-Indication Assumption
    S. Jay Olson
    (Submitted on 18 Feb 2020)

    Ambitious civilizations that expand for resources at an intergalactic scale could be observable from a cosmological distance, but how likely is one to be visible to us? The question comes down to estimating the appearance rate of such things in the cosmos --- a radically uncertain quantity. Despite this prior uncertainty, anthropic considerations give rise to Bayesian updates, and thus predictions. The Self-Sampling Assumption (SSA), a school of anthropic probability, has previously been used for this purpose. Here, we derive predictions from the alternative school, the Self-Indication Assumption (SIA), and point out its features. SIA favors a higher appearance rate of expansionistic life, but our existence at the present cosmic time means that such life cannot be too common (else our galaxy would long ago have been overrun). This combination squeezes our vast prior uncertainty into a few orders of magnitude. Details of the background cosmology fall out, and we are left with some stark conclusions. E.g. if the limits to technology allow a civilization to expand at speed v, the probability of at least one expanding cosmological civilization being visible on our past light cone is 1−v3/c3. We also show how the SIA estimate can be updated from the results of a hypothetical full-sky survey that detects "n" expanding civilizations (for n ≥ 0), and calculate the implied final extent of life in the universe.
    Do good work. —Virgil Ivan "Gus" Grissom

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    Quote Originally Posted by Roger E. Moore View Post
    Ambitious civilizations that expand for resources at an intergalactic scale could be observable from a cosmological distance, but how likely is one to be visible to us? The question comes down to estimating the appearance rate of such things in the cosmos --- a radically uncertain quantity.
    I wonder what resources would drive such a radical expansion? The accessible materials should be roughly the same per star system, in galactic habitable zones. Likewise, energy sources. Maybe the ETI never invented recycling? Or birth control? Moties 4 ever!
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Spacedude View Post
    Why communicate with us when there is really no need? It shouldn't be too difficult for ETs to observe, monitor, and learn everything they'd ever want to know about us without having direct contact. Being stealthy has a lot of advantages, one of the most important may be not having to answer a lot of annoying Human questions.
    Very true, also if they are far more advanced than we are (which we assume they must be since they are able to visit us) then they have no reason to contact us, nothing to gain from an engagement. But they could have plenty to lose, for instance much like in "War of The Worlds" they could be vulnerable to some form of biological contamination from our planet, or maybe somehow see us a potential threat. Maybe we are just not compatible much like the "ants" analogy, though for me this seems less credible since we do have a form of technology, though granted relatively very limited in comparison.

    We could make a long list of credible reasons for them not to make contact, all based on how we might react in similar scenarios ourselves. Then, they may have their own reasons way beyond our comprehensions, logic or understanding to remain hidden/silent.

    At the moment one thing we can be pretty confident of is that "if" we are being visited/observed then they/it up till now, has no immediate intention of making public contact! At least in a way that we could detect them.

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    Quote Originally Posted by cosmocrazy View Post
    Maybe we are just not compatible much like the "ants" analogy, though for me this seems less credible since we do have a form of technology, though granted relatively very limited in comparison.
    Termites build technically sophisticated mounds, ants farm fungus and "herd" aphids... Well, you get the idea.
    Advanced post-human minds would be hard enough for us today to predict the nature of. But post-alien? Fuggetaboudit!
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    A new paper on the Great Filter.

    https://arxiv.org/abs/2002.08776

    Observational Constraints on the Great Filter
    Jacob Haqq-Misra, Ravi Kumar Kopparapu, Edward Schwieterman
    (Submitted on 18 Feb 2020)

    The search for spectroscopic biosignatures with the next-generation of space telescopes could provide observational constraints on the abundance of exoplanets with signs of life. An extension of this spectroscopic characterization of exoplanets is the search for observational evidence of technology, known as technosignatures. Current mission concepts that would observe biosignatures from ultraviolet to near-infrared wavelengths could place upper limits on the fraction of planets in the galaxy that host life, although such missions tend to have relatively limited capabilities of constraining the prevalence of technosignatures at mid-infrared wavelengths. Yet search-ing for technosignatures alongside biosignatures would provide important knowledge about the future of our civilization. If planets with technosignatures are abundant, then we can increase our confidence that the hardest step in planetary evolution--the Great Filter--is probably in our past. But if we find that life is commonplace while technosignatures are absent, then this would in-crease the likelihood that the Great Filter awaits to challenge us in the future.
    Do good work. —Virgil Ivan "Gus" Grissom

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    A paper is out that says "life in the universe could be common, but not in our neighborhood". Now, what they mean by "our neighborhood" is the entire observable universe. WHAT? So we're essentially alone, you're saying?

    https://phys.org/news/2020-03-reveal...ghborhood.html

    "RNA is a polymer, meaning it is made of chemical chains, in this case known as nucleotides. Researchers in this field have reason to believe that RNA no less than 40 to 100 nucleotides long is necessary for the self-replicating behavior required for life to exist. Given sufficient time, nucleotides can spontaneously connect to form RNA given the right chemical conditions. But current estimates suggest that magic number of 40 to 100 nucleotides should not have been possible in the volume of space we consider the observable universe.... Indeed, the observable universe contains about 10 sextillion (10^22) stars. Statistically speaking, the matter in such a volume should only be able to produce RNA of about 20 nucleotides. But it's calculated that, thanks to rapid inflation, the universe may contain more than 1 googol (10^100) stars, and if this is the case then more complex, life-sustaining RNA structures are more than just probable, they're practically inevitable."
    Last edited by Roger E. Moore; 2020-Mar-06 at 12:54 AM.
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    Quote Originally Posted by Roger E. Moore View Post
    A paper is out that says "life in the universe could be common, but not in our neighborhood". Now, what they mean by "our neighborhood" is the entire observable universe. WHAT? So we're essentially alone, you're saying?

    https://phys.org/news/2020-03-reveal...ghborhood.html

    "RNA is a polymer, meaning it is made of chemical chains, in this case known as nucleotides. Researchers in this field have reason to believe that RNA no less than 40 to 100 nucleotides long is necessary for the self-replicating behavior required for life to exist. Given sufficient time, nucleotides can spontaneously connect to form RNA given the right chemical conditions. But current estimates suggest that magic number of 40 to 100 nucleotides should not have been possible in the volume of space we consider the observable universe.... Indeed, the observable universe contains about 10 sextillion (10^22) stars. Statistically speaking, the matter in such a volume should only be able to produce RNA of about 20 nucleotides. But it's calculated that, thanks to rapid inflation, the universe may contain more than 1 googol (10^100) stars, and if this is the case then more complex, life-sustaining RNA structures are more than just probable, they're practically inevitable."
    That sounds like a variation of the Creationist molecular complexity claims, which ignore that we are seeing highly evolved systems, ignoring chemical and biological evolution that leads to more complex molecules and living systems, and upsets the simple arguments about how improbable it is that complex molecules could result from randomly placed atoms.
    Last edited by Van Rijn; 2020-Mar-06 at 01:36 AM.

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