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Light, and from whence it cometh.

  1. Sep 4, 2009 #1
    Do light photons, of whatever frequency, emanate only from atoms, or can they sponaneously appear from, literally, nothing? If the former, does the atom have to be "complete", ie. with electrons dancing in attendance, or is the nucleous alone able to produce light photons. If so, is it also the case that individual protons and neutrons, (when suitably excited), are able to produce light photons?
    Separately, if we were able to approach a light source at, (say), 90% of light speed, would this motion effectively increase the frequency of the light waves such that visible light would appear as ultra-violet, or perhaps x-rays, or even as gamma rays. Also, the reverse. Could gamma rays be effectively lengthened to appear as x-rays, uv. or visible light if we were to recede from a light source? Or does nothing alter regardless of rate of approach or recession?
     
  2. jcsd
  3. Sep 4, 2009 #2

    ZapperZ

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    Take a clump of electrons, and shake it up and down. There, you've just produced light the way all the synchrotron light sources are producing.

    Zz.
     
  4. Sep 4, 2009 #3
    Photons can originate many ways and do not require a complete atom. They can be made from accelerating charges, particle-anti-particle elimination ect.

    To your second question: yes.
    What you are describing is called the Doppler effect. Special relativity says that the speed of light stays the same in every reference plane but the frequency of the light is frame dependent. There are special relativity formulas that relate how much the frequency is shifted by based on speed.
     
  5. Sep 5, 2009 #4
    Thank you for your replies. I had read somewhere that photons originated within the inner regions of stars, and that they faced a battle many years long to escape. In the 1970's it was thought that the pressure of gravity within the sun broke through the "electron shell" resulting in the nuclei sinking inward and leaving an electron "soup" in the outer regions. Is this no longer thought to be the case, and are electrons now thought to be distributed throughout the sun?
    RE the Doppler effect. On 13th. Sept. last year, the most distant single source gamma ray burst ever detected is thought to be from a distance of 12.8 billion light years. At these distances the expansion rate of the universe is said to be approaching that of light, or at least a high percentage thereof. Would these rays have provided the normal gamma ray signature, or would allowance have been made for their "stretching?"
     
  6. Sep 7, 2009 #5

    ZapperZ

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    This is a very strange thread.

    You are going off in a very strange tangent, and also making very weird and illogical ideas.

    Example: I get money from an ATM. Does that mean that the ONLY way to get money is from ATM's?

    You asked for ways in which light (i.e. EM radiation, photons, etc) can be generated. You have seen several different examples of non-atomic transition sources. Now, for some odd reason, you're going off in this "gamma ray burst" stuff.

    If you have a specific question about the source of highly energetic gamma ray from these celestial bodies, then please ask in the Astrophysics forum. If you have a general question on the many different ways that light can be generated, I believe that question has been answered.

    Zz.
     
  7. Sep 7, 2009 #6
    You're quite right, I'm waffling. I consider myself admonished.
     
  8. Sep 7, 2009 #7
    Can "admonish" really be used as an adjective?
     
  9. Sep 7, 2009 #8

    Vanadium 50

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    It's a participle.
     
  10. Sep 7, 2009 #9

    Danger

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    Add an anti-participle, and there's another light source. :uhh:
     
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