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Information carried by ray of light

  1. Jun 3, 2013 #1
    Does the light ray that had hitted a body carry the information about the body that it has hitted?

    Because when we see our own image in a mirror the image is same as of us.
    so do the photons of light carry information about the part from which they are reflected?

  2. jcsd
  3. Jun 4, 2013 #2

    Simon Bridge

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    Depends on what did the reflecting.
    A perfect mirror would just reflect the light as is - making no other changes. We may be able to deduce the existence of the mirror from the behavior of the image so in that sense information about the mirror has arrived with the light.

    Light scattered from various objects around us tell us a lot about those objects - though the "information" about the object's size, color, texture, eating habits, etc is not usually deducible from a single photon.

    So what do you mean by "information"?
  4. Jun 4, 2013 #3
    yes by information i mean the same as stated by you that is object's size, color, texture....
    But how does the photon take up such information?
  5. Jun 4, 2013 #4


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    It doesn't. The information isn't "carried" by the photon as one might carry a notebook or something. The photon merely has a certain amount of energy and a path that it takes. It reflects off the object you are looking at and enters the eye where it is directed onto the retina. The "information" about the object you are looking at comes from the detection of many photons in a short period of time. Your brain takes these detections and interprets them to form a visual image that you see and recognize.

    Also, it is only the experience your brain has with dealing with this sensory input that allows you to interpret it as meaningful data. A newborn, as well as a person who has just had their sight restored after being blind for life, have absolutely no idea what they are seeing, as their brains have never had this sensory input before and cannot interpret it.
  6. Jun 4, 2013 #5

    Simon Bridge

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    That's easy - they don't.
    That kind of information about an object scattering light is deduced from many many photons in combination with our lifetimes experience of seeing things and of handling a variety of objects close-up.

    Note: it's usually easier to talk about this in the wave-model for light.
  7. Jun 4, 2013 #6
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