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In general photons are not candidate for dark matter.
From the other hand stars constantly change matter into radiations (photons among them). And we can not measure radiation that does not hit us (although we can try to calculate it because radiation from star goes with same intensity in each spherical direction).
So my question is - are these answers below make sense? Is there any better answer why photons are not dark matter?
"Yeah, the only problem there is that we can observe photons. They make up about 0.001% of the energy density of the universe, far too little to explain dark matter."
(https://www.physicsforums.com/threads/could-dark-matter-be-light.549625/#post-3611412)
"Since we know that the universe is filled with a bath of light we can figure out how much energy is in it and account for it in the models of the universe. This is done, and the dark matter that we talk about is extra missing mass on top of that."
(http://curious.astro.cornell.edu/ab...660-could-photons-be-dark-matter-intermediate )
From the other hand stars constantly change matter into radiations (photons among them). And we can not measure radiation that does not hit us (although we can try to calculate it because radiation from star goes with same intensity in each spherical direction).
So my question is - are these answers below make sense? Is there any better answer why photons are not dark matter?
"Yeah, the only problem there is that we can observe photons. They make up about 0.001% of the energy density of the universe, far too little to explain dark matter."
(https://www.physicsforums.com/threads/could-dark-matter-be-light.549625/#post-3611412)
"Since we know that the universe is filled with a bath of light we can figure out how much energy is in it and account for it in the models of the universe. This is done, and the dark matter that we talk about is extra missing mass on top of that."
(http://curious.astro.cornell.edu/ab...660-could-photons-be-dark-matter-intermediate )