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Questions about photons

  1. Feb 24, 2015 #1
    1) Do photons eventually run out of energy and stop producing light?
    2) If atoms are non-solid and more than 99% empty space, what is the photon illuminating when it hits a surface?
    3) What is the actual light being produced, as opposed to the photon producing it?
    4) is it possible for a Higgs boson to grant a photon mass?
    5) Do photons have a lifespan?
    6) Scientists recently crystallized light. How is this possible if photons are massless?
     
  2. jcsd
  3. Feb 24, 2015 #2

    Nugatory

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    Questions 1-3 have no answers, because photons aren't what you think they are. They don't produce light or illuminate surfaces.

    Question 4, the answer is no. Photons have zero rest mass by definition.

    Question 5, the answer is no. Photons are stable as long as you stop them from interacting with anything else.

    Question 6, You will have to provide a source so that we can tell you whether what you've misunderstood what you read or it is just plain wrong.
     
  4. Feb 24, 2015 #3
    What am I implying about photons that is inaccurate, in reference to the first three questions? I know photons are massless particles/waves that eject from excited electrons, but I don't understand what is going on when a surface is illuminated and why that surface should have any quality whatsoever, being that atoms aren't even visible to most wavelengths of light.

    http://www.iflscience.com/physics/crystallized-light-reveals-potential

    This is the story about crystallizing light. I suspect the result was not as literal as is being implied.
     
  5. Feb 24, 2015 #4

    phyzguy

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    You seem to think that photons produce light. This is incorrect. Photons are light. Light is made up of energy packets called photons.
     
  6. Feb 24, 2015 #5

    mathman

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    Feynman's book (QED) will give you a good picture of what photons are and how they interact with matter.
     
  7. Feb 24, 2015 #6
  8. Feb 24, 2015 #7

    Nugatory

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    One way of judging whether the person who wrote that story has any idea what he's talking about is that it says something about Schrodinger's cat being in two states at once - and supports it with a link to a page that says the exact opposite.

    It's not science, it's sciency words strung together on a page in hopes of making you stay long enough to click the ads.
     
  9. Feb 24, 2015 #8
    If photons ARE light...what is the apparent affect of brightness? A large number of photons? Do photons have a fixed brightness?
     
  10. Feb 24, 2015 #9

    Nugatory

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    Each individual photon carries a fixed amount of energy, so all else being the same brighter more intense light means more photons arriving at the surface per unit time. (I say "all else being the same" because the energy of a photon is proportional to its frequency - a given number of blue-wavelength photons will deliver more energy and be "brighter" than the same number of red-wavelength photons).

    However, this is a really good time to start talking about what a photon is NOT. The first thing people think when they hear that "photons are particles" and that light is made up of photons is that a beam of light is made up of a stream of photons passing by and that the photons, being particles, are like little teeny bullets leaving the source and travelling at the speed of light through space until they reach their target.

    That little-bullet model is hopelessly wrong and misleading. To get an idea what photons are like, you could take mathman's advice from an earlier post and get hold of Feynman's book "QED: The strange theory of light and matter", or you could search the QM forum for some of the many posts in which this is discussed.
     
  11. Feb 24, 2015 #10

    Drakkith

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    A single photon itself has no brightness. It's just a little packet of energy that an EM wave deposits onto something. Brightness (or intensity, or a number of other technical terms) refer to power, which is energy over time. I'm not being nitpicky, it's a very important distinction. A single photon has a certain amount of energy, with the amount of energy per photon dependent solely upon the frequency of the EM wave. The higher the frequency the more energy per photon. All photons of a specific frequency EM wave have identical amounts of energy. The exact relationship is: E=hV, where E is energy, V is the frequency of the EM wave, and h is something known as 'the reduced planck constant', which is, by definition, a constant value. All that just means that as the frequency increases, the energy increases as well.

    Brightness, in terms of photons, is photons per unit of time. Since photons have energy we can measure this brightness in terms of power, measured in watts. So the more photons over time, the brighter a source of light appears, and the more power it puts out. A light bulb that consumes 50 watts of power will be brighter than a light bulb that consumes 25 watts of power. (By 'consume' I mean that the light bulb turns 50 or 25 watts of electrical power into light)
     
  12. Feb 24, 2015 #11
    When a photon hits a surface, does if just stay there? I know it's not like a little billet, but what happens to it once it hits a surface?
     
  13. Feb 24, 2015 #12

    jtbell

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    It gets absorbed by the material of the surface (or reflected, in the case of a mirror). In absorption, the photon disappears and its energy is transferred into some other form, e.g. thermal energy ("heat").
     
  14. Feb 24, 2015 #13

    Drakkith

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    The energy is absorbed and the photon no longer exists.
     
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