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I don't want to play with physical laws in a frivolous way.

Assuming that the nature of matter and energy is the same, can a high density of highly energetic photons produce a gravity force?

We do know that radiation is affected by space-time distortions, or in another way "feels gravity". Why do photons can (or cannot) produce a gravity field?

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possible duplicate of Does a photon exert a gravitational pull? –  Mostafa Jul 31 '13 at 14:15
    
Major edition was made to avoid duplicate questions. Thanks! –  cinico Jul 31 '13 at 16:18
    
The answer to the last question is no, read up on dark energy en.wikipedia.org/wiki/Dark_energy . Do not confuse it with dark matter: en.wikipedia.org/wiki/Dark_matter . Gamma rays interact with matter, that is how we "see" them. They can be neither dark matter nor more so dark energy (which is supposed to permeate all space). –  anna v Jul 31 '13 at 17:46
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There should be an enormous gamma ray flux to have enough effective mass to simulate dark matter. If you read the article you would see that the high energy photons come from specific points in the sky. If you read the article on darke energy you would see that it is even more complicated, because it is a postulated energy to explain the cosmological constant . It also should be uniformly spread and this is not observed: gamma rays of even higher energies would be interacting with each other giving visible signals of this. science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy –  anna v Aug 1 '13 at 3:37
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Questions should not be edited to completely change their character. –  dmckee Aug 6 '13 at 14:26
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marked as duplicate by John Rennie, Qmechanic Jul 31 '13 at 14:55

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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First of all, photons are not a pure form of energy. They are particles without rest mass, which means that they travel at the speed of light. Energy is a property of physical systems, the statement that something is energy makes no sense.

To answer your question: yes, electromagnetic radiation/photons contribute/s to the curvature of spacetime and therefore to gravity. The Einstein equations of general relativity related the curvature of spacetime to the stress-energy tensor, which contains not only mass but also energy. This also includes the energy of a photon.

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"Energy is a property of physical systems, the statement that something is energy makes no sense." You are right, my mistake. Expanding this question: Can a high (and I mean REALLY high) density of highly energetic photons be responsible for certain phenomena that usually requires dark energy to explain. –  cinico Jul 31 '13 at 13:29
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Dark energy is called dark because it cannot be "seen". The verb "see" includes the photon and the other elementary particles of the Standard Model. –  anna v Jul 31 '13 at 13:39
    
@anna I understand that, but I was assuming that such photons would not be visible in practice given the difficulty for detection of such high energetic particles. –  cinico Jul 31 '13 at 13:53
    
Well one can see gamma rays, which are very high energy photons. cfa.harvard.edu/~tergin/ergin.pdf –  anna v Jul 31 '13 at 14:15
    
I edited my question in order to better follow my reasoning and to avoid duplicate questions. @annav please check my edited question since it replies to your comment. thank you –  cinico Jul 31 '13 at 16:17
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