An Astrophysical Explanation for the Great Silence

Discussion in 'Astronomy, Exobiology, & Cosmology' started by etherometer, Jul 21, 2014.

  1. etherometer Banned Banned

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    An astrophysical model is proposed to answer Fermi's question. Gamma-ray bursts have the correct rates of occurrence and plausibly the correct energetics to have consequences for the evolution of life on a galactic scale. If one assumes that they are in fact lethal to land based life throughout the galaxy, one has a mechanism that prevents the rise of intelligence until the mean time between bursts is comparable to the timescale for the evolution of intelligence. Astrophysically plausible models suggest the present mean time between bursts to be ∼108 years, and evolutionarily plausible models suggest the rise of intelligence takes ∼108. Hence, this model suggests that the Galaxy is currently undergoing a phase transition between an equilibrium state devoid of intelligent life to a different equilibrium state where it is full of intelligent life.

    In a 1995 stu*dy, Steve Thor*sett of Prince*ton Uni*ver*si*ty in Prince*ton, N.J. cal*cu*lat*ed that such events, called gam*ma-ray bursts, might wreak hav*oc on an Earth-like plan*et if they oc*curred near it. But sci*en*tists don’t ful*ly un*der*stand the ex*tent of the pos*si*ble dam*age.

    Source: Cornell University Library.
     
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  3. cosmictraveler Be kind to yourself always. Valued Senior Member

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    No they don't and if you say they do how about some FACTS to prove what you say.


    No they don't have 108 years between events they vary quite a bit, where do you find this stuff?


    What are humans then devoid of intelligence and who knows if other alien life doesn't already exist and has been here for millions of years?
     
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  5. paddoboy Valued Senior Member

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    The obvious explanation for the "the Great Silence" is time and distance.
    The galaxy is a big place, and the observable Universe so much bigger.
    We won't even mention the Universe on the whole.
     
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  7. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    you might want to rethink this statement.
     
  8. mathman Valued Senior Member

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    I suspect 108 was meant to be \(10^8\). Life on earth has been around much longer. The Cambrian explosion (evidence of complex life forms) was about \(5.5*10^8\) years ago.
     
  9. rpenner Fully Wired Valued Senior Member

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    Taken from http://arxiv.org/abs/astro-ph/9901322 but actually from Journal of the British Interplanetary Society, January 1999, volume 52, pp. 19-22.

    cf. http://www.world-science.net/exclusives/070226_grb-life.htm 2007-02-26

    See also:
    S.E. Thorsett, “Terrestrial Implications of Cosmological Gamma-ray Burst Models”, The Astrophysical Journal, 444, L53 (1995). [Which is Reference 6 of James Annis's 1999 paper]

    Incorrect citation for a ArXiv pre-print.

    There is no original content in this OP.
     
  10. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Gamma ray bursts aren't on same time tables and I can't find anywhere that says they are, perhaps you can provide a link??
     
  11. etherometer Banned Banned

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    That's correct.
    BBC News article Ray burst is extinction suspect: We don't know exactly when one came, but we're rather sure it did come - and left its mark.
    Dr Adrian Melott, University of Kansas.
     
  12. etherometer Banned Banned

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    Stephen Hawking's Warning: Abandon Earth—Or Face Extinction: There is always the chance that a nearby supernova, an asteroid, or a quick and painless black hole could do us in.
     
  13. mathman Valued Senior Member

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    Where should we go?
     
  14. etherometer Banned Banned

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    Before it, we should know if a gamma-ray burst threat can be accurately predicted.

    When a black hole is born, it releases massive jets of gamma rays that are second in luminosity only to the Big Bang. These gamma-ray bursts are short in duration, but release such an incredible amount of energy that if one were to happen close enough to the Earth, every single living thing would be killed by the radiation (3).
    Fortunately, is quite unlikely that the Earth will be toasted by a gamma-ray burst. A gamma-ray burst releases energy in two focused jets in opposite directions. For a gamma-ray burst to decimate us, it would have to be pointed directly at us and be 200 light-years or less away. Given that there are no known stars within 200 light years of our Solar System that are big enough to release gamma-ray bursts, the denizens of the Earth probably

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    do not need to worry about being vaporized (4). Dr. Paul Groot, of the Harvard-Smithsonian Center for Astrophysics, offers the reassurance that �I think the Earth is in no danger� (5).

    Source:
    http://www.hcs.harvard.edu/~hsr/wp-content/themes/hsr/pdf/pdfsspring2007/goyalcenterlayout.pdf

    From The StarChild site. A service of the HEASARC, within the Astrophysics Science Division (ASD) at NASA/ GSFC:

    At least once a day, the sky lights up with a spectacular flash of gamma-rays coming from deep space. The brightness of this flash of gamma-rays can temporarily overwhelm all other gamma-ray sources in the universe. The burst can last from a fraction of a second to over a thousand seconds. The time that the burst occurs and the direction from which it will come cannot be predicted.
     
  15. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    even if it can be predicted,
    what would anyone do about it ?
     
  16. Write4U Valued Senior Member

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    Intuitively I agree with you, but (if I recall properly) Bohm postulated that the Universe is silent not because it is too empty, but because it is too full. (dark energy?)

    This was in relation to wavelengths represented in Bohm "Wholeness and the Implicate Order" as the "Holomovement" of the universe. There are so many wavelengths from Planck scale to near infinitely long, packed one on top of the other so tightly that the interference patterns make it near impossible to present a coherent result. I believe he estimated that one cubic centimeter of space contains as much energy as the entire universe. Howeve, this condition also yields near infinite potential for energy/matter to be formed.

    Perhaps this might account for those observed (random) energy bursts. A result of "harmonics"?

    Within the holomovement occasional wave harmonics are created which are observable (not silent).

    Perhaps someone can delve into this deeper than I. I like this vision, but i cannot defend it scientifically. The only thing I might venture is to say that if matter can "release" enormous amounts of energy, it should take enormous amounts of energy to "form" matter" {by a derivative of (E = Mc^2)?

    http://encyclopedia.thefreedictionary.com/holomovement
     
    Last edited: Jul 24, 2014
  17. wellwisher Banned Banned

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    Water is the second most abundant molecule in the universe behind hydrogen gas. According to the above, the combination of hydrogen gas and water, under pressure, makes the water more conducive for the formation of life where there is gamma radiation.
     
  18. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    are you seriously thirsty or something.
    almost every post i have read from you is about water,
    and not even relevant let alone being accurate.
     
  19. danshawen Valued Senior Member

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    Wha*t a c*ool way to p*revent krash*661 or so*me oth*er lurkin*g AI fr*om muc*king w*ith a p*ost.

    Gamma Ray bursts at cosmological distances are relentless; never go "silent" at all. The Compton telescope detects new ones all the time. What makes you believe that they pause for very long between bursts?
     
  20. rpenner Fully Wired Valued Senior Member

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    Are you endorsing this plagiarism?
     
  21. danshawen Valued Senior Member

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    "plagiarism"? If only that word even meant anything to the current generation.

    Sorry, I'm clueless as usual. No idea what you mean. What exactly has been plagiarized here, and by whom?
     
  22. Stryder Keeper of "good" ideas. Valued Senior Member

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    I think it's a bit worse than just Plagiarism. I've had my eye on this "new member" a little while, the reason of course is the fact that near enough every post has contained a quotation, citation or outright Plagiarism. It therefore seems to be a mixture of significance bot with the occasional human interaction to fox moderators from realising what it is. (It reminds me a bit of SCIGEN, so it could be a Scitopicgen bot attempt possibly merged with a program like XRumer to spam across multiple forums.)

    In any sense, I've allowed it long enough to prove the hunch. To the author of the bot, please don't bother using it here.
     
  23. danshawen Valued Senior Member

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    Well, that was interesting. @Stryder: Thanks for the moderation. Didn't seem to be able to reply for some reason.
     

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