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What is the maximum temporal resolution ever possible?

  1. May 17, 2009 #1
    I think I am right in saying that when we read a book, (for example), a photon hits the page and excites an atom, the electron that has been excited then returns to its previous state and in the process emits a photon corresponding to some energy band, (this defines the colour we see?).

    My question is, how quick;y does this happen, and does this put a restriction on our human 'frame per seconds'? ie. if an atom can only excite and de-excite once every second then we would only see what changes every second? Obviously there is more than one photon and the human eye and brain have there own limitations but I am assuming that humans have infinite processing power.

    If atoms do have a limit on this does it vary atom to atom or electron shell to electron shell?

    Cheers!
     
  2. jcsd
  3. May 17, 2009 #2
    When photons hit an atom like in this letter A, it excites the atoms, and usually de-excites in less than a microsecond or so. The 2p ->1s transition (de-excitation) lifetime in hydrogen is 1.6 nanoseconds, the 6h ->5g is 610 nanoseconds**. This varies from atom to atom, and shell to shell. Some pigments fluoresce, which means that they de-excite via multiple transitions. Some pigments phosphoresce, which means the emitted photon retention time is from milliseconds to minutes. When a de-excitation transition occurs, another photon is emitted, which travels about 1 foot per nanosecond from the page to your eye. On the other hand, our brain waves are a few hertz, or cycles per second.
    Sunlight is about 0.1 watt per cm2, or very roughly 3 x 1017 photons per cm2 per sec, so If our brain were faster, we should be able read out 1 page per millisecond. How many times per brainwave cycle are all the pixels in our eye retina read out? Please explain to me how our brain reads out the pixels in our eyes and transfers the images to our brain.

    ** There is a table of hydrogen atomic state lifetimes in Bethe & Salpeter "Quantum Mechanics of One and Two Electron Atoms", pg 266, and also in Condon & Shortley "Theory of Atomic Spectra".
     
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