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Thread: Several questions regarding light & optics (2)

  1. #1 Several questions regarding light & optics (2) 
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    I have several other questions :
    1. Does the electromagnetic spectrum have certain limits regarding frequency and/or wavelength?
    2. Can the speed of light be accelerated by artificial means?
    3. Can we make a laser using refraction alone?
    4. Can another parts of the e.spectrum beside visible light be made into a focused beam? (like laser)
    5. What determines color, frequency or wavelength excactly?


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  3. #2  
    Anti-Crank AlexG's Avatar
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    1. No

    2. No

    3. No

    4. Yes

    5. color is determined by which wavelengths are reflected and which are absorbed. Frequency and wavelength are related and determined by how much energy the light has.


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    6. And will the perception of depth vary if the eyes are closer or farther apart?

    and for alex g, can you please explain each of your answer from 1-4? thank you for replying.
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  5. #4  
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    Quote Originally Posted by TheAccursed View Post
    6. And will the perception of depth vary if the eyes are closer or farther apart?
    Makes you wonder how Oprah Winfrey sees the world... Maybe that explains something about her perceptions...
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    Forum Freshman WaterWalker's Avatar
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    Quote Originally Posted by TheAccursed View Post
    6. And will the perception of depth vary if the eyes are closer or farther apart?
    I would have to say yes. I am blind in one eye, so 3-d to me is the same as 2-d. the way I judge distance is the difference in size of known objects. having said that, I believe that is the way two eyes work as well. Only in the brain is the two images processed, intertwined, filtered and whatever else happens to form the main picture. I think eye depth might also have an effect. However, it would probably be quite small.
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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by TheAccursed View Post
    I have several other questions :
    1. Does the electromagnetic spectrum have certain limits regarding frequency and/or wavelength?
    No. Not in principle anyway. There is a problem that higher frequency means higher energy so it takes more extreme events to produce very high energy gamma rays, for xample.

    2. Can the speed of light be accelerated by artificial means?
    No. There's not much more to say about that.

    3. Can we make a laser using refraction alone?
    The SE in laser stands for Stimulated Emission. So you need a material which can emit photons and can be stimulated to emit photons.

    4. Can another parts of the e.spectrum beside visible light be made into a focused beam? (like laser)
    Before the laser there was the MASER which was microwave laser. In principle, a laser could operate at any frequency (although we don't have the technology).

    5. What determines color, frequency or wavelength excactly?
    We have three different receptors in the eye which respond to different frequencies (or wavelengths) of light. There are very roughly equivalent to RGB used in TV, etc. The brain analyses the mix of these frequencies and produces the sensation of colour.

    6. And will the perception of depth vary if the eyes are closer or farther apart?
    Maybe. But then the brain would adjust to make it look normal again. Pretty much every thing you see is generated in the brain from crude, messy signals from the eyes.
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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by WaterWalker View Post
    I would have to say yes. I am blind in one eye, so 3-d to me is the same as 2-d.
    I guess that means you will never be able to really understand the effect of seeing in 3D. But this might give you some insights: Do You See What I See? A Scientist's Journey Into 3-D : NPR
    Without wishing to overstate my case, everything in the observable universe definitely has its origins in Northamptonshire -- Alan Moore
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    Forum Bachelors Degree Kerling's Avatar
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    1. Does the electromagnetic spectrum have certain limits regarding frequency and/or wavelength?
    In principle no, however light beams can become defocused pretty fast, and after a certain energy height travelling through air instead of vacuum will make a problem.

    2. Can the speed of light be accelerated by artificial means?
    In principle yes, in materials which have a complex susceptibility and or permeability light would in fact travel faster through it. However waves have group-speed and phase speed. And although the light will travel faster, the information in the group speed cannot. This effect has already been demonstrated as negative refraction materials. They are though for now, rare.

    3. Can we make a laser using refraction alone?
    In principle, maybe. But not in a vaccum. Refraction is the ket element in most lasers (optical cavities) but you still need a pumping medium. This can be argon however or some other gas or dye.

    4. Can another parts of the e.spectrum beside visible light be made into a focused beam? (like laser)
    Yes, however this isn't always as simple. In principle one can use Free Electron Lasers to create practically any beam of light colour.

    5. What determines color, frequency or wavelength excactly?
    Provided a set speed. They are all the same. We however define colour.
    In the information age ignorance is a choice.
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    Quote Originally Posted by Kerling View Post
    2. Can the speed of light be accelerated by artificial means?
    In principle yes, in materials which have a complex susceptibility and or permeability light would in fact travel faster through it. However waves have group-speed and phase speed. And although the light will travel faster, the information in the group speed cannot. This effect has already been demonstrated as negative refraction materials. They are though for now, rare.
    I read about this in a science magazine some time back. It's been a while but if I recall it, the article claimed that a group had accelerated light using a supercooled chamber and a laser... but the details elude me. Because my old brain is eatin gits own neurons. Cannibalistic little organ.
    Can you shed any light on this?
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  11. #10  
    Forum Bachelors Degree Kerling's Avatar
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    Refractive index - Wikipedia, the free encyclopedia

    I must say, I didn't hear about this effect. I saw a few experimental results of the actual refraction, and so the theoretical derivation of it, during a presentation at the Landau institute for physics. What exactly do you want to know? I could make a short piece about it if you'd like.
    In the information age ignorance is a choice.
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