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I Where does light come from?

  1. Apr 20, 2016 #1
    What are the different mechanisms for producing light or radiation. Annihilation comes to my mind. What are some other ways?
    Also, what state of matter is light? Given that a high energy photon* flows for an infinite amount of time through 'empty' space will it stay as it is forever or would there be a possibility of it changing into something else?

    *[Edit: missed word]
  2. jcsd
  3. Apr 20, 2016 #2


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    Gold Member

    That's really the only way you can think of? How do you think light bulbs work?

    light is a quantum object.

    It will remain a quantum object if it doesn't hit anything but due to the accelerated expansion of space, its wave function frequency will continue to red-shift more and more forever.
  4. Apr 20, 2016 #3
    Fundamentally speaking, how does a light bulb work? And what other ways are there, could you provide a list please.

    Define quantum object.
  5. Apr 20, 2016 #4


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    Staff: Mentor

    Light is electromagnetic waves, and it is produced by accelerating electrical charges or otherwise changing the electromagnetic field at one point; ripples in the field spread out from the disturbance the way that ripples in water spread out from wherever the surface of the water is disturbed.
    There are many many ways of accelerating charges; one of the more common methods is to heat something because that causes the atoms to move around faster and they're made up of charged particles. That's how fires and incandescent light bulbs produce light, and the reason why a hot piece of metal will glow.
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