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The light spectrum

  1. Jul 4, 2010 #1
    A question about our vision

    Hi, I'm new here and this is the first time to post on this forum. I am really interested in physics and planning to major in mechanical engineer once I apply to colleges soon.

    However, I have a question that you people could either end the discussion quickly or have controversy.Well, here I go.

    Our human eye can only see light wavelength at around 780nm~620nm (color red) to 455nm~390nm (color blue/purple). It is true that some animals can see other light spectrum that we human beings cannot see such as bees: they can see ultraviolet lights.

    Then I have a question, human beings can see X-Ray pictures by converting the light spectrum compatible to our vision, right? (If not, please correct me, because I really am curious of how X-Rays work, wikipedia can be a pain) If that is the case, if we were to see lights beyond our range, will there be views that we have never seen before?

    Another question!
    Some people believe in ghosts, or should I say supernatural view. There are even exorcists or people who actually can talk with ghosts. The relation to ghosts and our vision is, animals who can see during the night such as bats and cats sometimes act abnormally. If this is the case, if we human can see objects without light, will we able to see ghosts or any super natural occurences?
     
    Last edited: Jul 4, 2010
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  3. Jul 4, 2010 #2

    DaveC426913

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    Re: A question about our vision

    And green.




    It is true that some animals can see other light spectrum that we human beings cannot see such as bees: they can see ultraviolet lights.

    Then I have a question, human beings can see X-Ray pictures by converting the light spectrum compatible to our vision, right? (If not, please correct me, because I really am curious of how X-Rays work, wikipedia can be a pain) If that is the case, if we were to see lights beyond our range, will there be views that we have never seen before?
    [/QUOTE]
    Well, yes, we can see inside the human body (which is transparent to X-rays), and we can see X-ray soruces in the sky.
    No, X-rays have shed no further light on ghosts or other supernatural phenomena.
     
  4. Jul 4, 2010 #3
    . . . .any super natural occurrences?

    Be aware that by definition, using science as the basis of technology to make observations can never detect anything "super" natural. Things are called supernatural for the very reason that they remain beyond the observation of science.

    The prefix "super" is used as in "superset", a set of things that includes all the real stuff plus stuff that might be real.

    If one aspired to show that things which currently are supernatural are real and observable, one would be obligated to perform scientific experiment, observation, documentation, analysis and presentation and submit it all to others for verification. Being a scientist is a much tougher gig than palm reader.
     
  5. Jul 5, 2010 #4
    What does 'supernatural' mean? Things either exist or they don't.

    If they exist, they are subject to natural 'laws' (don't like that expression but it'll do).
    So it's the domain of physics to study anything that exists.

    If they don't exist - what's the point of even having a name for them?
    As for studying them... :bugeye:
     
  6. Jul 5, 2010 #5
    Well, this is why we have the words, and fields of study, called 'epistemology' and 'metaphysics'.
     
  7. Jul 5, 2010 #6
    We also have the fields of study called 'astrology' and 'theology'
    I prefer the expression 'doesn't exist' - saves an awful lot of wasted time.
     
  8. Jul 5, 2010 #7

    sophiecentaur

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    The expression "doesn't exist" can involve a matter of degree. Phenomena are often seen and 'interpreted' in different ways - particularly by our non-scientific brethren. They may use 'fictitious' forces / rays / fields etc. to explain things in a way not too dissimilar from the way the Scientists use models (like waves, photons and fields) to predict and explain things. Scientists often fall into the trap of talking in terms of what's 'really happening' just the same as some non-scientists do. The only essential difference may be in the degree of predictability and repeatability involved. Science has, of course, a much more rational approach to these things and is a much more reliable way forward (usually) but I wonder just how rigid the dividing line really is. There certainly seems to be an overlap which includes the most rational of the non-scientists and the more fanciful of the Scientists in less 'objective' fields in Science.
     
  9. Jul 5, 2010 #8
    It's a lovely day outside.
    I think I'll go and play in the garden.
     
  10. Jul 5, 2010 #9

    sophiecentaur

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    Are there fairies at the bottom, though?
     
  11. Jul 5, 2010 #10

    DaveC426913

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    No. The whole concept of supernatural critters is predicated on the assumption that they do not operate according to natural laws as we currently understand them. << that's key.
    I think the flaw in this logic is pretty obvious.
     
  12. Jul 5, 2010 #11
    I certainly don't blame you for taking that position. But if every last person did that there would be little to no growth in knowledge.

    Astrology and theology, in my view, are not fields of study per se. My epistemological observation is that they are bodies of statements which claim to be knowledge. The nature of the origins of these statements is typically 'revealed' as opposed to 'observed'.

    Your position might perhaps be different if almost all philosophers of the previous century weren't nearly worthless to humanity in real life. They are frequently stimulating and provocative but rarely do anything to put food on the table or advance technology. (There are exceptions, and my favorite is Alfred North Whitehead, who insisted that philosophers at least try to do something worthwhile.)
     
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