a rainbow requires an observer

Discussion in 'General Science & Technology' started by Epictetus, Apr 26, 2012.

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  1. Epictetus here & now Registered Senior Member

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    Is it true that a rainbow requires an observer? Unlike a tree falling in a forest, which must certainly make a noise (IMHO),wouldn't the refracted light of a rainbow need to be seen to actually exist?
     
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  3. keith1 Guest

    All levels of vibration are remotely detectable by devices, and no observer need be present to record the event.
     
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  5. AlexG Like nailing Jello to a tree Valued Senior Member

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    The light is still refracted, whether anyone sees it or not.
     
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  7. Cavalier Knight of the Opinion Registered Senior Member

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    This was somewhat tougher question decades ago, along the lines of Einstein's question to Bohr, "Do you really think the moon isn't there if you aren't looking at it?"

    The standard answer now is that so long as any photons (and the wave functions of those photons) generated are interacting with other particles/wave functions on a large enough scale (including passing through the air), there would certainly be enough quantum decoherence to, in effect, collapse the wave functions of the photons. That would mean the photons would be in a definite state, and if the photons are there, in the proper wavelengths, so the rainbow would be.

    That assumes we accept that the "wavelength" of light is the same as "color." On a more philosophical level, "color" is really an interpretation our brain makes as an easy way of discerning different wavelengths. Without a brain there, the photons would exist, and would each have a wavelength, but if you think of color as an artifact of brains interpreting stimuli, then without a brain you could not have "color," and that might lead one to conclude there is no "rainbow."

    (The same can be said for sound, though, and you took a position on trees falling. One could argue in the same way that a falling tree would cause pressure waves in the air, what we call "sound waves", but without a brain to interpret, is a complex patter of pressure waves the same as "sound?")
     
  8. leopold Valued Senior Member

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    yes, an observer needs to be present to see the colors.
    the droplets will still divide the the wavelengths but the colors will be absent without the observer.
     
  9. Buddha12 Valued Senior Member

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  10. tantalus Registered Senior Member

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    It really isnt on a philosophical level though, Is it? What began as a philosophical question, finished with a scientific answer.
     
  11. C C Consular Corps - "the backbone of diplomacy" Valued Senior Member

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    The phenomenal appearance of a rainbow (the exhibited qualitative colors) is what requires at least a certain kind of sensory and cognitive system for organizing and discerning inputted data as such. Really, the manifestation of any spatially-extended form is dependent upon outer relations converging upon a receptive agent that can interpret that information (just try being dead and still having the world manifested as visual, audible, etc, evidence). The planet Mars, as it existed in itself, certainly wouldn't be a visual image of a red dot in the sky, or a round reddish body as viewed from orbit around it, or the flat landscape as apprehended from on its surface, or any of a variety of abstract technical descriptions in the physical sciences (what would brainless Mars or the brainless universe being doing dabbling in descriptions?). Things having their be-ing as observed bodies are as they are thought about or presented as existing outside themselves, as Mars or whatever exists to something else (humans in this instance).

    Idealism was not about denial of things existing when not observed, but that they existed in some other manner than as conscious experiences or phenomena. Somewhere in either the Three Dialogues or Siris, even Berkeley eventually got around to acknowledging that a tree wouldn't be maintained as some biotic-like multiple-view set of perceptions in God, but in some noumenal-like way which he knew not what. Leibniz dropped the need for "God perceiving everything", but left God responsibility for his pre-established harmony; and then Kant dispensed with God altogether in his critique of theoretical reason, tossing a bone to theists only in his practical philosophy.
     
  12. Epictetus here & now Registered Senior Member

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    CC! It's a shame that they have a great mind like you, along with your body, just cutting grass.
     
  13. Fraggle Rocker Staff Member

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    If two people are a couple of miles apart, don't they see the rainbow in slightly different form or orientation?
     
  14. Aqueous Id flat Earth skeptic Valued Senior Member

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    Does that include all sky light?
     
  15. Fraggle Rocker Staff Member

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    It depends on what you mean by "color." We define certain wavelengths as red, yellow, green, etc. Even if we're not there to see it, the light still has the same wavelength.

    Now all animals don't see the same way. Our eyes have three kinds of photoreceptors; dogs have only two so they see much less variety of colors, and for compensation they see better in dim light in black and white. Cats have even worse color vision and even better night vision than dogs.

    But many animals have more kinds of photoreceptors than we do. They can see clear up into the ultraviolet range. For example, this is how birds can tell males from females when they look the same to us: their feathers have ultraviolet pigmentation that we can't see.

    Bees have something like seven different kinds of photoreceptors. The ultraviolet spectrum is a riot of color to them. That's how they can tell which flowers are ripe enough to have nectar.
     
  16. Believe Happy medium Valued Senior Member

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    Colors are not an artifact of your perception, they are divided by the wavelength of the light present. If the wavelength is present, the color is there plain and simple.

    http://en.wikipedia.org/wiki/Visible_spectrum
     
  17. Aqueous Id flat Earth skeptic Valued Senior Member

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    Taking into consideration what FraggleRocker said, I now glean something different from what leopold said.

    I now understand that leopold means that the diffraction into red, orange, yellow, green, blue and violet still occurs, but without a human present to see it, the image is absent, since that particular image as we know it is a product of human perception. If some animal were to observe it, that animal's mind might project the whole spectrum into shades of red, so the coloring we know and perceive is absent.

    This kind of reasoning goes along the lines of that familiar question: what if the color palette I see does not look to you like the color palette you see, but we can't corroborate this fact because we have no way to communicate our perceptions to each other exactly?
     
  18. Fraggle Rocker Staff Member

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    It's certainly true that I have no way of knowing what image pops into your mind when you see an object that I call "orange" or "blue." Nonetheless we both agree on which frequency of the light spectrum we call "orange" or "blue." In some cultures they break the spectrum down differently, for example making a fundamental distinction between orangish-red and a more pure red, or regarding blue and green as different shades of one color.

    Nonetheless, if we are both shown an object that is a specific shade of red or bluish-green, and then shown ten objects in slightly different shades of each of those colors, we will unfailingly agree on which one is the same color as the original, even if we argue over that color's name.

    My point was that this is not true over species boundaries. Blue and green look absolutely identical to a cat, and the subtle tinges of ultraviolet that distinguish a ripe flower from an unripe flower in a bee's eye are completely invisible to us.

    Of course some people lack one of our standard three color receptors, so they see colors more the way dogs do and don't understand why we distinguish between shades that look the same to them. This is what we call "color-blindness." They're actually blind to only one of what we call the "primary colors," and their world is not the black-and-white that the term seems to imply.
     
  19. Cavalier Knight of the Opinion Registered Senior Member

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    The wavelength is there, but "color" is an interpretation of wavelength made by the visual cortex. It's no different than "sounds. There are complex compression waves that move through the air (or other bodies), but "sound" is an interpretation of those waves that is created in the eye/brain working in concert.

    Proof of that is that some people are color blind. It's not that the wavelengths do not exist for them, it's that their visual systems do not process those waves in the same way most people do, in a way that does not result in them seeing the "color" is certain wavelengths in the way that others will.
     
  20. C C Consular Corps - "the backbone of diplomacy" Valued Senior Member

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    Inverted spectrum / qualia related fare keep hanging around as if no fatal criticism of such possibilities has been provided yet. But I agree that we have to assume humans are sharing the same operating system (barring minor perceptual and interpretative deviations and the more major ones that are known or detectable); or that we have no good grounds for assuming otherwise. And, if such inverted conditions were really that behaviorally and experimentally undetectable, then they could be ignored for never achieving a clinical status, anyway -- they would be unverifiable scenarios (amounting to metaphysical).
     
  21. C C Consular Corps - "the backbone of diplomacy" Valued Senior Member

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    Also, if these oscillating environmental energies (EM waves, atmospheric pressure waves, etc) had internal manifestations as images or sounds -- it would be a situation amounting to panexperientialism. This as much applies to contact-related perceptions. A thorn doesn't possess "sharp pain" as part of its properties and the wafting molecules from rotten eggs don't have that strong odor literally inhering in themselves. These qualitative properties are supplied by the nervous and neural systems of a body or conscious agent in response to outer disturbances transpiring on its assorted kinds of receptive, sensitive tissue.
     
  22. Fraggle Rocker Staff Member

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    No, this is not true. Colorblind people have only two types of photoreceptors rather than the standard three. Their eyes literally cannot distinguish one-third of the colors that ours can. It's a physical difference, not psychological. The brain does not receive the signal because the signal is not sent; it has nothing to do with interpreting the signal.
     
  23. C C Consular Corps - "the backbone of diplomacy" Valued Senior Member

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    A kind of running joke as to the various things that "CC" could stand for. Next month it might be anything from "Cheap Copyreader" to "Conference Caller". Serves me right for randomly choosing a couple of letters for a username.

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