1. Subscribersonhouse
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    22 Feb '12 02:27
    Originally posted by Shallow Blue
    We've looked at the electromagnetic output from thousands of sources - millions, if you count SETI@Home. Not one of them showed the kind of pattern you would expect from an intelligent broadcast. At least, not one of them showed the kind of pattern you would get from our kind of intelligence. On that count, at least, we are exceptional.
    Now, of ...[text shortened]... ife there, or anywhere. There's life here. That's exceptional, right there.

    Richard

    This statement was made, the thread is closed but I wanted to add my 3.14159 cents worth: All that shows is we may have missed a wavefront of RF that came and went and we were just in the wrong place at the wrong time.

    Like I said, suppose we have start sending out RF and one of several things happen where we stop sending RF, for instance, we convert everything on Earth to fiber optics and give up transmitting RF, maybe convert the stuff that needs to go by RF, we now do with short range IR.

    So as we are doing now, a tremendous amount of information is flying across the globe via the internet but not much of that is getting off the planet due to satellites sending signals down to earth and earths stations sending out signals that can be picked up but say at some point we develop some other technique, say X ray lasers that can transmit Exabytes of data per second and so we give up the RF thing.

    So another civilization hears the start of our transmissions and then a couple hundred years later, no more RF. Do they then conclude we all died? Had a major war? Hit by an asteroid? None of those things happened, we just went to a different technology.

    That could happen quickly, say within one hundred years, we might find better, cheaper, less energy intensive means of transmitting a trillion times the information we used to send but with no RF. So we then have a short wavefront, say less than 500 years of transmitting RF.

    That is a very short time on the galactic scale, and that 500 year wavefront of detectable RF can come and go and be gone and another civilization just like ours would miss it completely. So it might be with the lack of detection we already have gone through.
  2. Cape Town
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    22 Feb '12 08:48
    Originally posted by sonhouse
    That could happen quickly, say within one hundred years, we might find better, cheaper, less energy intensive means of transmitting a trillion times the information we used to send but with no RF. So we then have a short wavefront, say less than 500 years of transmitting RF.
    Its already happening. Optic fibre is already the most efficient method of transmitting data and is being laid throughout the world. Cable tv already replaced rf tv in the US, and it won't be long before the internet will replace rf tv everywhere. In fact, tv itself will only last as long as there are people with no internet access or slow internet access. As soon as play on demand becomes available to everyone, people will switch and tv will die.

    Once everyone has optic fibre to the home, the only reason left for RF will involve the requirement to move ie cell phones, laptops, internet/tv to the car, communications to aeroplanes etc.

    How far away would cell phone signals be detectable using current SETI technology? I don't think its very far at all.
  3. Subscribersonhouse
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    22 Feb '12 12:282 edits
    Originally posted by twhitehead
    Its already happening. Optic fibre is already the most efficient method of transmitting data and is being laid throughout the world. Cable tv already replaced rf tv in the US, and it won't be long before the internet will replace rf tv everywhere. In fact, tv itself will only last as long as there are people with no internet access or slow internet access ...[text shortened]... phone signals be detectable using current SETI technology? I don't think its very far at all.
    We could, theoretically, even develop non electromagnetic communications, remember, light is electromagnetic, just a lot shorter wavelength than RF. I am thinking about neutrino's.

    We can already make neutrino's on demand, it would just be an engineering feat to modulate them for communications use. For instance, to communicate with submarines, we now use extreme low frequency RF, like 50 hertz or so, with its inherent low data rate. If we could use neutrino's, they would go through the entire planet like a hot knife through butter, or for instance, communicate directly to astronauts on the far side of the moon. So if that were to be commonplace, there would be no RF of ANY kind to detect, which is another reason why we are not detecting transmissions as of yet.

    Even if we could detect Earthy type RF transmissions from Andromeda galaxy, for instance, we could detect the entire galaxy at once but the same short wavefront time could defeat finding any signs of life.

    So that seems to me to leave only direct optical imaging with huge telescopes finding things like methane in an alien atmosphere and other signs of life or direct imaging of cities and so forth on alien planets, which could require a matrix of telescopes the size of the solar system but it could be done if there was the will and political support, several in space telescopes around the distance of Pluto connected together with laser beams could theoretically give a resolution of a telescope the size of the entire solar system. That would allow us to see licence plates on Alpha Centauri🙂
  4. Cape Town
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    23 Feb '12 08:34
    Originally posted by sonhouse
    That would allow us to see licence plates on Alpha Centauri🙂
    And the first alien transmission that SETI picks up turns out to be a list of speeding tickets from Alpha Centauri, because they too have one of those telescopes. 🙂
  5. Cape Town
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    23 Feb '12 08:44
    Another major factor to consider here, is that as our rf transmissions transition to digital, we compress the data. The better the compression, the more random the patterns. With good data compression, and no 'marker' signals, our transmissions would be indistinguishable from noise. Current SETI projects are designed to look for analogue signals and would probably not spot digital signals with good data compression. It won't be long before most of our rf transmissions are digital - simply because it is more efficient. (greater fidelity, better use of band width, lower energy requirements etc).
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    23 Feb '12 14:42
    Originally posted by sonhouse
    This statement was made, the thread is closed but I wanted to add my 3.14159 cents worth: All that shows is we may have missed a wavefront of RF that came and went and we were just in the wrong place at the wrong time. [/b]
    Sure, that's possible. Very possible. It's also very possible that they're emitting in a part of the Spectrum we don't look at, or using encryption which turns their emissions into static (that one is very, very possible, if only because using PKZIP on all that interplanetary data would have the same effect...).

    Nevertheless. We've looked, and we've seen nothing.

    That may mean that we haven't looked hard enough, or it may mean that they're intentionally hiding, or it may mean that we were just unlucky. But it doesn't automatically mean that any of those must be the case. It may also mean that there's nothing out there.

    Consider: you've lost your keys. You search the couch. You find nothing. Now, it's possible that the keys are on the mantelshelf, or it's possible that you didn't look for the keys well enough. But one thing is certain: your keys existed yesterday, so they must still be somewhere today.
    Now consider: someone claims that he's lost a gold ring in your couch, and would you please return it? You search the couch. There is no ring (you just found your keys, btw). Now, it's possible that the ring was lost elsewhere. It's possible that you didn't search well enough. But it's also very much possible that someone is trying to hustle you, and there is no ring.
    If the ring was your brothers', you assume that he is not lying - maybe mistaken as to the ring's whereabouts, but not claiming the existence of a non-existent ring. But if the claim comes from some random geezer who was brought into your house by some claimed FOAF crashing your birthday party, well...

    Our search for extra-terrestrials is not like your search for your keys. We do not know that they exist. It's like your search for the ring. And the people telling us that honest, guv', they exist, well... They're either evident nutcases from the cousin-marrying parts of the USA, or wishful thinkers using very iffy mathematical random-number formulas, or new-age loons seeing patterns where there aren't any (which is as old as Schiaparelli, and probably older).

    Aliens may exist. But our failure to find even the slightest evidence that they do is, in the complete absence of any real arguments that they must, rather evidence - not proof! - of their non-existence than a post-modern reason to keep on dreaming.

    Richard
  7. Subscribersonhouse
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    23 Feb '12 16:16
    Originally posted by Shallow Blue
    Sure, that's possible. Very possible. It's also very possible that they're emitting in a part of the Spectrum we don't look at, or using encryption which turns their emissions into static (that one is very, very possible, if only because using PKZIP on all that interplanetary data would have the same effect...).

    Nevertheless. We've looked, and we've ...[text shortened]... non-existence than a post-modern reason to keep on dreaming.

    Richard
    Negative evidence does not mean they don't exist of course. Suppose they are high beings who communicate by telepathy. I'd like to see the telescope that could suss THAT out🙂 Of course we think real telepathy would be impossible but maybe they would do it through modulated magnetic pulses or something, or IR like from a remote to its TV, but two way. Or X-ray for that matter.

    I just read a report where the guy says forget looking at RF, try to see if an atmosphere has signs of life or civilization. I would imagine a sufficiently powerful telescope could see life on our planet from many light years away just from the lights of our cities.

    It would seem a fairly safe bet if we saw lights on a directly imaged planet, we could say some kind of civilization is on that planet. We might even be able to see by the spectrum, if they had passed the need for incandescent lights and had switched to LED's which would have a totally different spectrum, a band of peaks and nulls where incandescent's would have a broadband radiation within limits.
  8. Standard memberSoothfast
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    23 Feb '12 17:55
    SETI is not equipped to detect the alien equivalent of "I Love Lucy" television programming leaking out of the atmosphere, unless perhaps the alien civilization is just a few lightyears away. SETI is looking for powerful transmissions from extraterrestrials that are being broadcast for the explicit purpose of "getting noticed". We're talking about intelligent life's equivalent of a supernova here, which can be expected to be considerably rarer than actual supernovas. It's not just space that's the problem here, it's time as well. There could be a million different intelligent species in the galaxy over the course of a billion years, and among those that form a civilization that doesn't immediately destroy itself one has to imagine that the window of time when they're willing and able to send out electromagnetic "hellos" is rather narrow.

    That SETI has not received a signal yet is hardly surprising to me. To posit that alien civilizations likely do not exist based on the silence of a few decades is to spectacularly fail to grasp the magnitudes of the probabilities involved.
  9. Subscribersonhouse
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    23 Feb '12 21:33
    Originally posted by Soothfast
    SETI is not equipped to detect the alien equivalent of "I Love Lucy" television programming leaking out of the atmosphere, unless perhaps the alien civilization is just a few lightyears away. SETI is looking for powerful transmissions from extraterrestrials that are being broadcast for the explicit purpose of "getting noticed". We're talking about intell ...[text shortened]... des is to spectacularly fail to grasp the magnitudes of the probabilities involved.
    As time goes by we will be able to detect smaller and smaller levels of RF, not that it may do us much good from our previous arguments. The Allen array is already detecting the Voyagers, now at something like 10 billion miles, 16 billion Km, from the sun, using just a couple of their scopes. When it is completed it will be awesomely sensitive.

    We can detect ourselves if the signal got here, even from the other side of the galaxy, say 50,000 ly away.

    Don't forget, an RF signal IS a supernova sized signal compared to the RF background of a typical star and planet, even the rumblings of Jupiter is nothing compared to a narrow band transmission of say a radio telescope radar signal sweeping from the Arecibo radio telescope in Puerto Rico.
  10. Cape Town
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    24 Feb '12 10:22
    Originally posted by Shallow Blue
    Aliens may exist. But our failure to find even the slightest evidence that they do is, in the complete absence of any real arguments that they must, rather evidence - not proof! - of their non-existence than a post-modern reason to keep on dreaming.
    I don't like your analogy, it is far from accurate.
    Much better is this:
    You are on a farmstead in a fairly remote part of the country. You stand on your porch at night and look around for signs of other people walking around. You don't see anyone within the range of your porch lights, nor do you see any signs of torches or car lights in the distance. Do you conclude that you are alone for 100km around where you live? Sure there is nobody nearby shining a strong enough light towards you, but that is hardly even strong evidence that there is nobody not shining a light, or that there is nobody shining a light in a direction away from your or whose light is obstructed by something else.
    I am essentially saying that although no signal is evidence that aliens are not all over our front porch trying their best to communicate with us, it is hardly significant when it comes to deciding whether or not there are aliens at all. And I am only talking about our own galaxy. When it comes to other galaxies (of which there are billions) we haven't even looked. So concluding that there are no aliens would be equivalent to concluding that there are no people on earth in my analogy.
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    25 Feb '12 00:39
    so basically, there is a very short window of opportunity given any advanced civilization that they would be generating signal noise that can be picked up before they switch over to high tech systems and no longer transmit noise that can be picked up.

    that pretty much makes seti looking of a needle in a haystack the size of the solar system.
  12. Standard memberSoothfast
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    25 Feb '12 01:11
    Originally posted by VoidSpirit
    so basically, there is a very short window of opportunity given any advanced civilization that they would be generating signal noise that can be picked up before they switch over to high tech systems and no longer transmit noise that can be picked up.

    that pretty much makes seti looking of a needle in a haystack the size of the solar system.
    SETI is betting that civilizations are out there sending out signals intended to be heard by other civilizations. Yes, it could pick up "noise pollution" from E.T., but more likely we're counting on E.T. making a call.
  13. Subscribersonhouse
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    25 Feb '12 02:23
    Originally posted by Soothfast
    SETI is betting that civilizations are out there sending out signals intended to be heard by other civilizations. Yes, it could pick up "noise pollution" from E.T., but more likely we're counting on E.T. making a call.
    It still comes down to being in the right place at the right time. Suppose the plane of the ecliptic on a hypothetical planet is tilted way out of the plane of the galaxy, they could send signals out on their ecliptic and we would never hear the signal even if we could had it been aimed at us.

    Even planets IN the ecliptic plane of the Milky Way with advanced civilizations may be aiming their transmissions to the wrong place, we miss that signal. It could have been like that for the famous Wow signal, on pulse and the transmitter is doing a whirlygig changing angles of transmission, and we miss the next one.
  14. Standard memberRJHinds
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    25 Feb '12 07:12
    Originally posted by twhitehead
    I don't like your analogy, it is far from accurate.
    Much better is this:
    You are on a farmstead in a fairly remote part of the country. You stand on your porch at night and look around for signs of other people walking around. You don't see anyone within the range of your porch lights, nor do you see any signs of torches or car lights in the distance. D ...[text shortened]... no aliens would be equivalent to concluding that there are no people on earth in my analogy.
    Isn't this the same argument atheists use for "there is no God" comment?
  15. Subscribersonhouse
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    25 Feb '12 13:38
    Originally posted by RJHinds
    Isn't this the same argument atheists use for "there is no God" comment?
    Yes except for the fact that this is not the spiritual forum. I don't think anyone brought in the concept of god here. This has nothing to do with a god, your god, his god, whatever. We are discussing SETI, the attempt to find extra terrestrial civilizations from their radio or laser broadcasts. This is a totally technological discussion.
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