The light is in our eyes...

Discussion in 'Physics & Math' started by Quantum Quack, May 21, 2017.

  1. danshawen Valued Senior Member

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    A camera does not detect time at all, unless it is a video or a motion picture camera, in which case the shutter speed and frame rates come into play. The saccades of our own eyes replace the shutter or frame rate for motion.

    This is a valid, if obscure, observation.
     
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  3. danshawen Valued Senior Member

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    For those who do not understand QQ's "Ol Roemer" reference, Roemer was the astronomer who surmised the speed of light from an astronomical observation of the timing of the orbit of a moon (Io) of the planet Jupiter, using the diameter of the Earth's orbit in diametrically opposed seasons to perform the necessary timing measurements. The difference observed would have been about 2 astronomical units, or about 17 light minutes. That's how much the period of Io's rotation / eclipse of Jupiter's moon Io would have been delayed.

    From this experiment, Roemer concluded that the speed of light was considerably greater than one Earth diameter in one second, but because the radius of the Earth's own orbit had not been agreed upon at the time, that was as much accuracy of the speed of light Roemer was able to manage.

    This same method was later used to determine the eccentricity of Earth's own orbit, no doubt.
     
    Last edited: May 27, 2017
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  5. Write4U Valued Senior Member

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    I'm not gonna play this game.
    I've answered your questions to best of my knowledge. If I am wrong, enlighten me.
     
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  7. Seattle Valued Senior Member

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    That has nothing to do with the questions you've brought up anymore than Write4u bringing up Special Relativity.
     
    Last edited: May 27, 2017
  8. danshawen Valued Senior Member

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    Roemer was of course able to surmise the speed of light from spatial timing considerations.

    Saccade duration is about 200 milliseconds, corresponding to a frame rate of about 5 Hz. This rate makes sense, in terms of optic neuron synapse prop delays. No wonder slower frame rates for video and movies are an easy illusion.

    The speed of visual signals in the optic nerve is proportional to light intensity, which allows some pretty interesting physics classroom demonstrations with pedulums and sunglasses held in front of one eye. This probably explains why slower frame rates for movies are mildly annoying also. If one scene is lighter and the next one is dark or vice versa, your visual system will detect this as flicker.

    Anything else vision related we haven't already discussed in the thread?
     
  9. DaveC426913 Valued Senior Member

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    Right. So drop the metaphysical stuff and just deal with the actual physics stuff.

    To do that, you'll have to accept, for the sake of discussion that, what we see is what we see.

    Now, the OP is about where is the light that is on our eyes.
     
  10. Write4U Valued Senior Member

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    I agree, and if I may offer a minor addition.
    A camera has two modes of controlling incoming light for proper exposure. Lens aperture and shutter-speed.
    A wide aperture allows for fast shutter speed to "freeze" the picture, but you lose depth of field.
    Slow shutter speed allows for a small aperture, which increases depth of field, but at slow shutter speeds a moving object will be recorded as *blurry*, unless you pan the camera to keep the moving object in the center of the frame. But then the background becomes *blurry*.
    OTOH. if the camera is in motion, a fixed object will also show a blur, unless a fast shutter speed is used.

    In any case a camera doesn't care about the length of time the light has traveled before it reaches the lens. Nor does the eye. They both rely on available lumens *present* at time of exposure or perception.
     
    Last edited: May 27, 2017
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  11. Write4U Valued Senior Member

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    I merely included it, because at high speeds the Doppler effect alters the wave length of the incoming light from approaching or receding emitters. Blue shift, Red shift.
    It's a minor point, but it IS science and related to vision (observation)
    Am I too far out in left field here?
     
    Last edited: May 27, 2017
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  12. Seattle Valued Senior Member

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    Yes.

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    There is nothing related to Special Relativity going on here. We aren't talking about space expanding and travelling at close to the speed of light. We're just talking about light itself and SR doesn't apply in any meaningful way.

    That's why no one uses the math of GR when classical Newtonian physics will do. If you aren't talking about vast distances and/or speeds approaching the speed of light the differences are too small to be significant (in general). Yes, there is GPS but we aren't talking about GPS now.

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  13. Quantum Quack Life's a tease... Valued Senior Member

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    No you were telling me to:

    How is that answering any questions?
    It sounds like you want to censor any criticism of science?
     
  14. Quantum Quack Life's a tease... Valued Senior Member

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    you really need to make up your mind...

    What we see is what we see (objective)
    or
    What we see is what we interpret from the data entering our eyes (metaphysically subjective)...which is it?
     
  15. DaveC426913 Valued Senior Member

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    No. That's for a metaphysical discussion in another forum.

    Here, physics works the way mainstream physics says it does. You'll have to frame this argument in those terms, and start a new thread about the metaphysics elsewhere.

    You need to make up your mind which discussion you want to have, and where.
     
  16. Quantum Quack Life's a tease... Valued Senior Member

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    deleted - futility
     
    Last edited: May 28, 2017
  17. Quantum Quack Life's a tease... Valued Senior Member

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    deleted futility
     
    Last edited: May 28, 2017
  18. Quantum Quack Life's a tease... Valued Senior Member

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    deleted futility
     
    Last edited: May 28, 2017
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  19. origin Heading towards oblivion Valued Senior Member

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    Thank God, are we finally done with this mess?
     
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  20. Quantum Quack Life's a tease... Valued Senior Member

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    well there was the issue of ....nah just kidding!!!
     
  21. Seattle Valued Senior Member

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    With over 9,000 posts, you've been around here long enough to know that the answer to that question is "no".

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    Last edited: May 28, 2017
  22. Quantum Quack Life's a tease... Valued Senior Member

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    Don't worry, me and origin go way back. Well before delta t=o then d=0 or 0.999... =1 discussions... hee hee
     
  23. hansda Valued Senior Member

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