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Could Photon Mass Contribute to the Rotational Dynamics of Galaxies and Negate the Need for Dark Matter?

Posted by Guy Pirro 03/18/2019 06:45PM

Could Photon Mass Contribute to the Rotational Dynamics of Galaxies and Negate the Need for Dark Matter?

The rotation of stars in galaxies like our Milky Way is puzzling. The orbital speed of stars should decrease with their distance from the center of the galaxy, but in fact stars in the middle and outer regions of galaxies have the same rotational speed. This may be due to the gravitational effect of matter that we can't see. Although researchers have been seeking it for decades, the existence this imaginary construct referred to as “Dark Matter” has yet to be definitively proven -- We still don't know what it is made of or even if it exists at all. With this in mind, physicists in Germany have suggested that the rotational dynamics of galaxies might be explained by other factors. They hypothesize that the mass of photons, which are particles of light, might be responsible. The mass of a photon is extremely small and is usually ignored when analyzing atomic and nuclear processes. However, such a vanishingly tiny mass could have an effect on large-scale astrophysical phenomena.


  • ab7698 [Aaron Barson]
  • 03/21/2019 07:18PM
To be a viable explanation of dark matter, the photon density in the halo for a given galaxy would have to correlate with the amount of dark matter calculated for that galaxy. I don't think that is the case.

I thought the same thing when I first read this. How could the total mass of photons in the galaxy come anywhere near the mass of the Dark Matter that would be needed to correspond to the observed rotational dynamics?

So I went to the actual paper that these researchers published and found that the hypothetical effects they are investigating are not the result of increased gravity due to the mass of the photons, but rather to a mechanism known as Maxwell-Proca electrodynamics where the photons create additional centripetal forces in the galaxy that imitate gravitational pull and produce effects in the galactic rotation that, to an outside observer, may look like gravity.

Here's a quote from the paper:

"Maxwell-Proca electrodynamics corresponding to finite photon mass causes substantial change of the Maxwell stress tensor and, under certain circumstances, may cause electromagnetic stresses to act effectively as “negative pressure.” The paper describes a model where this negative pressure imitates gravitational pull and may produce forces is comparable to gravity and even become dominant."

Hope this helps,

Guy Pirro