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Transparency of the sun to extremely long wavelength photons

  1. Aug 14, 2011 #1
    Hi, new here.

    This came up briefly elsewhere and we didn't have the cerebral fire power to get very far with it.

    Consider very, very long wavelength photons, (or conversely, very very low energy photons) produced inside the sun. Wavelengths we are looking at are in the range of 1 light year up 13 billion light years or so, the maximum size wavelength possible in our universe in this era. (or would that 'other' number apply?)

    Do these photons escape from inside the sun? Considering the difficulty in making an antenna for these wavelengths (there are rather large), we think the sun is essentially transparent to this radiation.

    We were also looking at the power output of the sun at these wavelengths, the individual photons are of vanishingly low energy, but, conversely, there might be quit a few of them.

    We were looking at some solar luminosity formula, but one of the terms was for surface area of the sun, if the entire mass of the sun radiates at these wavelengths, is the surface area of the sun important in calculating the power emitted?

    And if this all physics 101 topics, my apologies.
  2. jcsd
  3. Aug 14, 2011 #2


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    If you speak about wavelengths bigger than diameter of Sun, it makes little sense to think about transparency of the Sun. Waves of such wavelengths cannot be localized precisely enough to say if they go through the Sun, or pass it by.
  4. Aug 14, 2011 #3
    Yes, any such photons 'passing by' from elsewhere in the universe will 'ignore' the sun, but what of photons like that produced inside the sun itself?
  5. Aug 14, 2011 #4
    What reason do you have to believe such photons are even produced by the sun?
  6. Aug 14, 2011 #5


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    Then, as the E-M wave representing them is much longer than your object (Sun), they are not flat waves, as you used to analyse in optics, but rather are dominated by magnetic or electric part. And you should ask what happen if you put a ferrite antenna in the middle of the SUn, and how its magnetic field is screened. Or what happens if you put 1/10000000 wavelength long dipole and what would be its emission.
    My intuition tells me that in both cases the screening will be close to perfect.
  7. Aug 14, 2011 #6

    Because the sun is warmer than absolute zero.

    (Sorry, don't mean to be snarky, but I think that is what is needed to generate these guys. My understanding is the only photons 'forbidden' are those with wavelengths exceeding the size of the universe.)
  8. Aug 14, 2011 #7
    As for the transparency of the sun to these very low energy photons, if any externally generated ones were passing by (say they are relics of the BB), the sun would be unable to intercept any of them because of it's small relative size, so if such a photon happened to be produced in side the sun, wouldn't it too find the sun to not be an impediment to it's passage out?
  9. Aug 14, 2011 #8


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    Just because something isn't 'forbidden' by a certain physical law is not sufficient to guarantee existence. Unicorns are not 'forbidden', and yet they are hardly ubiquitous. If you know of an observed physical process which generates extremely long wavelength radiation, then your the answer to your question will have some meaning.
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