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Another thread on this site established that the photon has a gravitational field of its own. Then the photon must loose energy to the gravitational wave the photon makes when it travels through space, I assume? But I have never seen a calculation of the red shift due to this effect by mainstream astronomers. But prof. Jian-Miin Liu (Nanking University) has some interesting papers on this subject on the internet, using the GTR as his theoretical background. I would be very glad to hear of your views on this.

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    $\begingroup$ Could you reference/cite the other link you mention in your first line, thanks $\endgroup$ – user140606 Jan 20 '17 at 23:26
  • $\begingroup$ Please note that the expansion of the universe is seen not just in the redshifts of photons, but in the dilation of time intervals between events occurring at high redshifts, like typeIa supernova lightcurve decays. The latter cannot possibly be attributed to GWs (or any of the other tired light ideas). $\endgroup$ – Rob Jeffries Jan 23 '17 at 7:47
  • $\begingroup$ Also physics.stackexchange.com/questions/240440/… $\endgroup$ – Rob Jeffries Jan 23 '17 at 7:52
  • $\begingroup$ Gedanken experiment: A laser at great distance from Earth with its beam directed against the Earth. Between the laser and the Earth there is a tired light mechanism. The laser light is consequently red shifted. A timer placed on the laser opens and closes a light valve, e.g. one sec. on - one sec. off and so on. Every period of light has a fixed number of light maxima, not changed by the mechanism. But we receive a longer laser beam because the number of maximas x the longer wavelength = give a longer period than one sec. with a constant velocity of light. Nova curves add nothing to red shift. $\endgroup$ – Göran Rosander Jan 25 '17 at 5:44
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    $\begingroup$ @Countto10 It was a time ago so I don't remember clearly,but I think an experiment with two antiparallell laser beams draw my attention. $\endgroup$ – Göran Rosander Jan 25 '17 at 12:40
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Not everything that has a gravitational field emits gravitational waves. Gravitational waves are emitted if the gravitational field is time dependent and has a time dependent quadrupole moment.

The gravitational field of a propagating photon, or indeed any propagating particle, does not have a time dependent quadrupole moment so it does not lose any energy by emission of gravitational waves.

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When a photon is absorbed, then one does expect a ringing of the gravitational field. Some of the energy of the photon will dissipate as a gravitational wave under those conditions.

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  • $\begingroup$ I don't believe this is accurate. Can you provide any references or explanation? $\endgroup$ – DilithiumMatrix Jan 23 '17 at 1:23
  • $\begingroup$ As an example of a propagating particle let us take a neutron star - a massive particle indeed but well inside the definition "any propagating particle". Scientists have been awarded the Nobel Prize for their scientific work on two such particles and with precision calculated the energy loss when the 'particles' propagate in a gravitational field. Do you really mean "any propagating particle? $\endgroup$ – Göran Rosander Jan 25 '17 at 5:23

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