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Thread: What is light?

  1. #1 What is light? 
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    That's a good question to ask. I know one thing is for certain that I can observe. If I stare at a white wall with a good light source, I can actually see particles raining down on the wall. To me it looks like rain of very fine particles hitting the wall at a great speed. Some people will say I am full of you know what or I am lying, but this is not the case. I have benn able to do this since a child and I am a grow man. maybe I have unique vision. I do not know, but I do know that I can see the particles raining down.

    So what is it exactly?


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  3. #2 Re: What is light? 
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    Quote Originally Posted by mauriecb
    That's a good question to ask. I know one thing is for certain that I can observe. If I stare at a white wall with a good light source, I can actually see particles raining down on the wall. To me it looks like rain of very fine particles hitting the wall at a great speed. Some people will say I am full of you know what or I am lying, but this is not the case. I have benn able to do this since a child and I am a grow man. maybe I have unique vision. I do not know, but I do know that I can see the particles raining down.

    So what is it exactly?
    See the sticky thread for links to lectures by Richard Feynman on quantum electrodynamics. That will give you some inkling into the best available understanding.

    What you have described is actually somewhat close to the truth, in some sense. But it is physically impossible to see photons as distant objects, because it is photons themselves that constitute light, and photons do not reflect or emit photons. So what you describe is some sort of artifact created by your body. Is your vision normal in other respects ? You might want to consult an ophthalmologist.


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  4. #3  
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    Typical response from someone. I have perfect vision my whole life. Just because you can't see it doesn't mean I can't.
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    You are not actually seeing particles hitting the wall. I am capable of seeing this phenomenon is many different situations as well. I can just about summon it at will. When I was younger, I liked to imagine that they were neutrinos even though I knew it was absolutely ridiculous, that it's impossible to see them with the naked human eye . It's optical illusion, an issue with eye health. The eyes are capable of creating many things, like floaters, blobs of color. In the case of migraines, one can see squiggly lines and various auras. Seeing these things in your field of vision does not constitute their existence outside of yourself. As another example, sometimes I see things that look like magnified cells floating in my vision, strings of little bubble-looking things, resembling caterpillars. Sometimes I see swirling balls of color dancing around in my field of vision (it's fun until they become a distressing hindrance by effectively blinding me), usually purple or green in color.
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  6. #5  
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    Quote Originally Posted by mauriecb
    Typical response from someone. I have perfect vision my whole life. Just because you can't see it doesn't mean I can't.
    Typical response from someone who doesn't want to accept the reality of the situation.

    I'm not flaming you here, but I am disagreeing with you about what you are actually seeing. The human eye is not capable of seeing particles, much less a photon on its own.

    There is a reasonable explanation for what you're seeing, and while I don't know exactly what it might be I do have an idea of what it could be. When I look at the sky on a clear day, I can see tons of tiny dots swirling and moving around in the sky. I used to assume they were gas molecules bouncing around in my vision until I did some searching and found out what was truly going on.

    Your eye has a lot of liquid that is constantly flowing around, but we never really pay much attention to it. That liquid can collect dust, dirt, etc. In my analogy of the sky, what I was seeing was tiny minuscule dust particulates flowing around in the liquid of my eye.

    Perhaps this is what you were seeing, simply free-floating amounts of dust and dirt so tiny that they reflect in our vision in such a way to create the illusion of particles.
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  7. #6 Re: What is light? 
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    Quote Originally Posted by DrRocket
    it is physically impossible to see photons as distant objects, because it is photons themselves that constitute light, and photons do not reflect or emit photons. So what you describe is some sort of artifact created by your body.
    QFT.


    To the OP: There is no offense intended. Everyone agrees that you are seeing something, and even that it's quite cool. The issue is that you cannot see photons by themselves. I don't mean this to be a "typical response," nor in any way negative... unless by "typical" you mean "true and accurate."
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  8. #7  
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    Maybe you should dust more often.

    You would need to 'see' the photons coming at you, if you could.
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  9. #8  
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    So this is why I see it as rain coming down and not the usual floaters as some people see. It looks like rain very tiny rain of light. So doctor explain how this is possible for me to see?
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  10. #9  
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    This is as close as I can describe it. I will have to draw it out on pain or something to describe what I see. This is close, but not exactly.

    http://3.bp.blogspot.com/_KpqQ9rqe9a...s_bruenjes.jpg
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  11. #10  
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    Let's first start by exploring the dynamics of visual perception in humans.

    When we see things, it is the result of light hitting the neural receptors at the back of our eye (the retina).

    There are two types of receptors: Rods and cones.

    Rods detect light in a binary (yes/no) fashion, and tend to be located more densely at the periphery. When there is any light, it triggers the rod, and this helps us detect motion.

    Cones detect color, and there are three different types. The cone will only fire if light of a certain frequency range (color) hits it.

    When these receptors fire, a signal is sent toward the occipital cortex at the back of the brain, and the collection of signals is brought together like an algorithm to interpret what we are seeing.

    The brain (many different parts) do the interpretation.


    What we see is a model of the world put together in our brain as a result of the stimulus to our neural receptors. In short, what you see is a model of the world, and not the world itself. That model can be inaccurate due to many reasons, some of which are issues in the eyes, in the receptors, in the information pathways, or in the brain itself.


    Regardless, Dr.Rocket's answer remains the correct one. I hope the above helps you to understand where the issue may be a little better. There is likely something (not wrong, but) different in your eyes or brain than the majority of humans around you.




    EDIT: Btw - This has come up quite a few times from other posters, too:

    http://www.thescienceforum.com/viewt...er=asc&start=0
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  12. #11  
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    I understand how our eyes work and no i do not see swirly lines. It pours down fast like very tiny minuscule rain. I have to look at the light source in my peripheral vision to see it better. White backgrounds are easiest for me to see it. It will pour down like tiny rain from the light source. If there are a lot of colors around the color backgrounds seem slower than the white and then the colors will make it pour from every direction and not a stream like the source.
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  13. #12  
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    I would guess that there is some sort of issue in the firing of your cone receptors, and/or the signals they are sending to the cortex and how those get interpreted.
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    I like your satirical humor, but no I am not on drugs. I only wish that it was so that way i had an excuse. No I do not walk around like this. I have to concentrate on what i am looking at in order for it to happen. My eyesight is 20:15 in one eye and 20:20 in the other.
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  15. #14  
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    Quote Originally Posted by mauriecb
    I like your satirical humor, but no I am not on drugs.
    Wait, what? I implied no such thing.


    Quote Originally Posted by mauriecb
    My eyesight is 20:15 in one eye and 20:20 in the other.
    Your visual acuity is not relevant to the suggestion I made.
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  16. #15 Re: What is light? 
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    Quote Originally Posted by mauriecb
    That's a good question to ask. I know one thing is for certain that I can observe. If I stare at a white wall with a good light source, I can actually see particles raining down on the wall. To me it looks like rain of very fine particles hitting the wall at a great speed. Some people will say I am full of you know what or I am lying, but this is not the case. I have benn able to do this since a child and I am a grow man. maybe I have unique vision. I do not know, but I do know that I can see the particles raining down.

    So what is it exactly?
    Blood cells of blood flowing over your retina. (It's a normal visual effect, so don't worry)
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  17. #16  
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    Who says I am worried? So its Okay for you to believe in Black holes, but not Okay for you to see what's in front of you? You sure you are ready for science?
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  18. #17  
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    No matter how you cut it, you will be wrong about the thing you see being photons. Alternative (but still less plausible) possibilities could be that you're seeing fluctuations in the light source itself, or points where the light cancels itself, or rayleigh scattering as the higher frequency portion of the white light bounces off some of the air it is passing through.

    Here's a link for that last thing: http://en.wikipedia.org/wiki/Rayleigh_scattering

    Anyway. Whether it's a problem with your eyes, or an interesting phenomenon that you are seeing, you need to keep an open enough mind to accept that your first hypothesis (that you're seeing photons move) is almost certainly wrong, and move onto another theory. Don't accuse the rest of us of being closed minded if you're the one who has jumped to a conclusion and wont' let go of it.
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  19. #18  
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    If you could see light in particles this way, and your vision in different from what other people would have, you should see every light particle this way... you cant say you see some light particles within the field of ''ordinairy'' vision its one or the other and both types of ''vision'' should lead to a type of vision which we all have... which is the normal way in which we see
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  20. #19  
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    Quote Originally Posted by mauriecb
    Who says I am worried? So its Okay for you to believe in Black holes, but not Okay for you to see what's in front of you? You sure you are ready for science?
    scientific vision hallucination
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  21. #20  
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    I know one thing is for certain that I can observe. If I stare at a white wall with a good light source, I can actually see particles raining down on the wall. To me it looks like rain of very fine particles hitting the wall at a great speed. Some people will say I am full of you know what or I am lying, but this is not the case. I have benn able to do this since a child and I am a grow man. maybe I have unique vision. I do not know, but I do know that I can see the particles raining down.
    If it is indeed perception of individual photons, the phenomenon should be more pronounced at low light levels, when there are fewer photons, and by inference, staring at a white wall while reducing the lighting should result in the rate of particles dropping off until at low light levels you would see the slow arrival of individual quanta. I do not perceive any of this myself.

    The fundamental problem with this experiment is that it contains uncontrolled elements. In this case we have all the brain's optical processing to deal with, and this is very complex. You need to design experiments that compensate for this.

    [/quote]
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  22. #21 I can see it too,obviously tyhese peopel can't 
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    Maurie,

    I have seen this phenomenon since I was a kid as well. Could not tell if it was raining on cloudy days (that is first time I remember seeing the particles). Dad asked me if t was raining and told him yes, as it turned out I was seeing the particles.

    I have learned to "tune out" the particles unless I try to see them.

    I have astigmatism, do you? I can se pretty well in the darkness. My daughter can see the "rain" too.

    The average human hearing range is variable, some people sensing infra and some ultrasound, I think this applies to vision as well.

    I have a theory and it may sound odd, but I think it is the resultants of cosmic ray particles striking air molecules in the upper atmosphere and the smashed "debris" raining down on earth and interacting with air on the way down.

    When I look at a laser beam projected on to a surface, I see particles too like a mini cloud near the intersection point with a surface. I am not sure how other people see lasers but the effect is similar to the particles albeit on a smaller scale.

    I too have overall good distance vision, though my close up is somewhat less as I get older. Mind you I could see the particles when I was 6 and did not wear glasses

    Don't listen to the "nay sayers", they don't have the "ancients gene"! HAH

    Jim
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  23. #22  
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    I can see a trip to pseudoscience coming...
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