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Thread: Echo of a wave length

  1. #31
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    Quote Originally Posted by Strange View Post
    It is not a matter of tuning (except within relatively narrow ranges, such as RF). It is the fact that different frequency ranges may require completely different technologies to detect a signal. You can't "tune" an RF antenna to receive visible light.
    And some sensors are just not suited to recording anything related to the wavelength. A bolometer array (frequently used for IR imaging) is only going to measure heating due to the absorbed radiation, and don't really care about the wavelength. If you know the emissivity of the surface you are imaging, you can infer its temperature and thus the peak wavelength of its emissions, but the bolometers alone won't give you that information.

  2. #32
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    Quote Originally Posted by speach View Post
    'Echo' is there something in the new wavelength, the one that has been altered by the sensor to make it visible to us, that what type of EM and it's wavelength before it was decoded by the sensor?
    I don't think anybody has brought this up yet, so I thought I would. I think it's also misleading to think of a sensor as altering the wavelength. In reality, light doesn't really change its wavelength (I think), rather a photon is absorbed and another is emitted (not really the same photon). So you can calculate what the former photon's wavelength would have been (I think), but that's not really an echo, because that photon in turn would have been produced by some process, and you can't really identify that. I might be wrong about this, however.
    As above, so below

  3. #33
    Well some nebulae in space can absorb one wavelength and emit another. But if you built a detector that absorb one wavelength and gave off another it would pretty useless as an observing tool.
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  4. #34
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    Quote Originally Posted by Jens View Post
    I don't think anybody has brought this up yet, so I thought I would.
    I think it's also misleading to think of a sensor as altering the
    wavelength. In reality, light doesn't really change its wavelength
    (I think), rather a photon is absorbed and another is emitted (not
    really the same photon).
    That idea is central to what I wanted to say, but gave up on
    because there is just too much that needs to be said.

    In post #4, Shaula mentioned scintillators, which come close to
    what you (and maybe speach) describe. A scintillator absorbs a
    photon of one wavelength and then immediately emits a photon of
    another wavelength. If the absorbed photon is not visible, such as
    infrared or ultraviolet, and the emitted photon is visible light, then --
    with some kind of amplification -- the existence, time and place of
    the absorption can be seen more or less directly by human eyes.
    If the properties of the scintillator are known (the meta-information
    Strange brought up), then it might be possible to know or at
    least narrow down the wavelength of the absorbed photon.

    But for most methods of observing or recording invisible light, the
    means of displaying the observation is completely independent of
    the wavelengths absorbed. Any wavelengths can be absorbed by
    a sensor, transformed into electric charges or activated chemicals
    or glowing phosphors or magnetic spots, and then be displayed in
    whatever medium you choose, possibly not involving light at all.

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  5. #35
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    Quote Originally Posted by speach View Post
    No you have not got the concept of the question, it has nothing to do
    with the wavelength that the receiver collects. I am fully aware that
    every type of wavelength needs a receiver that is 'tuned' to that peculiar
    band of wave lengths. The question was (I'm getting very fed up with
    the narrow minded answers Strange is the only person that seems
    to have grasped the question. Now the question was, after the said
    wavelength as been received and translated into a form we can
    interpret is there an Echo still in that converted image that refers
    to the original length?
    "The original length" is "the wavelength that the receiver collects",
    isn't it?

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  6. #36
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    Quote Originally Posted by Swift View Post
    I suggest you lose the attitude. No one is obligated to answer your questions at all and they are doing you a favor by doing so. If they didn't understand the question, maybe you need to do better explaining it.
    I have no attitude. Of course no one is obligated to answer. It just appears no is able to answer except Strange. It is a very simple question here goes again After a incoming wavelength (any wavelength) is resolved, in the resolved image is there any echo of what the original wavelength was simple enough? I suspect that the answer is no, but it's worth finding out what others with more education than me think.

  7. #37
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    I bet I end up on the naughty stair for that answer!

  8. #38
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    Think About SETI

    You are pretty much describing a sprectum analyzer, nicely explained here:

    https://en.wikipedia.org/wiki/Spectrum_analyzer

    They are wonderfull devices. Frequency, power, sidebands, ets., all diplayed right in front of you.

  9. #39
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    Quote Originally Posted by speach View Post
    I have no attitude. Of course no one is obligated to answer. It just appears no is able to answer except Strange. It is a very simple question here goes again After a incoming wavelength (any wavelength) is resolved, in the resolved image is there any echo of what the original wavelength was simple enough? I suspect that the answer is no, but it's worth finding out what others with more education than me think.
    I just read about an example that might be relevant. A telescope in Italy called ASTRI, part of the Cherenkov Telescope Array. It captures Cherenkov Radiation. This is created by the passage of (charged) muons travelling at more than the speed of light in air. The interesting thing is that the frequency of the light tells them the energy of muon. So this seems to fulfil both your ideas in the OP: an "echo" (the energy) of the original signal (the muon) and a generic receiver (it detects light but also, indirectly, muons).

  10. #40
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    Quote Originally Posted by John Mendenhall View Post
    You are pretty much describing a sprectum analyzer, nicely explained here:

    https://en.wikipedia.org/wiki/Spectrum_analyzer

    They are wonderfull devices. Frequency, power, sidebands, ets., all diplayed right in front of you.
    I've mentioned spectrographs in trying to guess what speach wants. Apparently that's "narrow minded".

    I don't think they understand that there's not just one wavelength to consider, or that wavelength is literally just a length.

  11. #41
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    Quote Originally Posted by Strange View Post
    I just read about an example that might be relevant. A telescope in Italy called ASTRI, part of the Cherenkov Telescope Array. It captures Cherenkov Radiation. This is created by the passage of (charged) muons travelling at more than the speed of light in air. The interesting thing is that the frequency of the light tells them the energy of muon. So this seems to fulfil both your ideas in the OP: an "echo" (the energy) of the original signal (the muon) and a generic receiver (it detects light but also, indirectly, muons).
    The wavelength of the light, along with knowledge of the instrument and the process by which the light is generated, tells us something about the muons. But suppose you are an observer who sees the emitted light but has no idea what sort of transducer is producing it or what might have stimulated the tranducer. In that case you would get no information about the nature of the muons or whatever might have caused the phenomenon just from the wavelength of the emitted light.

    For an analogy consider a TV set. If the spectrum of the light from the screen is all we have to go on, we cannot tell whether the signal was in one of the old analog bands or a digital successor.

  12. #42
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    The point is, if you measure a wavelength, you get a wavelength. Period. No "echoes."

  13. #43
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    speach,

    We still don't really know for sure what you mean by "echo".
    Unless and until you explain it, nobody but you will ever know.

    Why not answer my questions in post #17 ? Here they are again:

    Could you describe a "generic receiver" for us? What form would
    the output have? How would you interpret that output? Describe
    in as much detail as possible an example of how such a receiver
    would work and how it would be used.

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  14. #44
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    OP suspended for three days, so you might want to hold further questions and remain patient for answers.
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  15. #45
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    Quote Originally Posted by Ken G View Post
    The point is, if you measure a wavelength, you get a wavelength. Period. No "echoes."
    What I'm asking for the hundredth time is when the wavelength is translated into a form that we can see/hear is there a residue in the translated visual/audio from that tells us what the wave length that formed the "translation" was. a very simple question. And I expect that the answer is no from all the garbage that has been written here.

  16. #46
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    Quote Originally Posted by speach View Post
    What I'm asking for the hundredth time is when the wavelength is translated into a form that we can see/hear is there a residue in the translated visual/audio from that tells us what the wave length that formed the "translation" was. a very simple question. And I expect that the answer is no from all the garbage that has been written here.
    Simple questions don't always have simple answers. This one is too vague and poorly defined to be answered with a simple "yes" or "no". The best you're going to get can be summed up as "in some limited ways, maybe, depending on what exactly you mean".

    Why do you think people keep asking you for clarification? What possible motive could they have other than trying to figure out how to answer your question? If you want a real answer, you need to quit ignoring people who are trying to figure out what you're after, or throwing tantrums because they're not reading your mind, and actually pay attention to what they're saying.

  17. #47
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    Quote Originally Posted by speach View Post
    What I'm asking for the hundredth time is when the wavelength is translated into a form that we can see/hear is there a residue in the translated visual/audio from that tells us what the wave length that formed the "translation" was. a very simple question.
    I know it's simple, that's why I told you the simple answer. No. So why do you keep repeating the simple question that has a simple answer? This is the third time I've told you.

  18. #48
    If you have an original signal and you add another wavelength you and you know the final wavelength you can probably find out the wavelength that has been added but if that is not what you going after I am at my wits end because I have mentioned all the situation which a signal can be altered.
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  19. #49
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    Quote Originally Posted by speach View Post
    What I'm asking for the hundredth time is when the wavelength is translated into a form that we can see/hear is there a residue in the translated visual/audio from that tells us what the wave length that formed the "translation" was. a very simple question. And I expect that the answer is no from all the garbage that has been written here.
    And what we're telling you for the 100th time is that your question is ill-formed. You are demanding -- rudely -- that we answer your question in just the way you want in your head. The problem is that you are using English words in totally nonsensical ways. That you get "garbage" in reply is due to the "garbage" way in which the question has been posed.

    A wavelength, as Ken G has correctly pointed out, is a length. Your question is therefore wholly equivalent to asking "Is there a residue of a meter when this meter undergoes some completely undefined process." Since there is no such thing as a "residue of a meter," there can be no answer to your question other than "no". You've therefore been given the correct answer already. That you don't like it is really your problem. If you want a different answer, ask a better question. So far, you've written gibberish, and the rest of us struggle with a guessing game to decode it.

    So, really, drop the complaining attitude, face the fact that you yourself are the source of the problem, and are therefore the one most responsible for fixing it. Learn enough of the correct meaning of the terms you are using so that you can communicate with humans other than you. Yes, you are using English words, but you have strung them together in meaningless ways. Fix that, and there's a chance of getting a non-"garbage" answer.

    GIGO and all that, you know.

  20. #50
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    Quote Originally Posted by speach View Post
    What I'm asking for the hundredth time is when the wavelength is translated into a form that we can see/hear is there a residue in the translated visual/audio from that tells us what the wave length that formed the "translation" was. a very simple question. And I expect that the answer is no from all the garbage that has been written here.

    Okay, and that finshes this thread and gives you some more free time.
    infracted for insulting the people who want to help you.
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