I How does gravitational self-interaction affect the Milky Way Galaxy?

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Gravitational self-interaction is a complex topic, primarily described by the nonlinear nature of the Einstein Field Equation. The prevailing view is that such interactions have negligible effects on the shape of galaxies or the rotation curves of stars, leading to the postulation of dark matter to explain these phenomena. Some researchers, including Alexander Deur, propose alternative theories that challenge this standard viewpoint, but their ideas have not gained widespread acceptance in the scientific community. Additionally, the MOND theory suggests that General Relativity may not accurately describe gravity at low accelerations. The correctness of Deur's mathematics remains an open question, with limited confirmation from other physicists.
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It is believed that gravity interacts with itself. I assume that gravity between stars increases. Does gravitational self-interaction change the galaxy's shape or increase the rotation curves of stars?
 
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KurtLudwig said:
It is believed that gravity interacts with itself.
More precisely, the Einstein Field Equation is nonlinear, which can be described as gravity interacting with itself. There is a lot of complexity lurking here; see this Insights article series for more information:

https://www.physicsforums.com/insights/does-gravity-gravitate/

KurtLudwig said:
I assume that gravity between stars increases.
No, gravity interacting with itself is not that simple.

KurtLudwig said:
Does gravitational self-interaction change the galaxy's shape or increase the rotation curves of stars?
The standard viewpoint at present is that any such effect is negligible, because gravity is too weak in this regime for any nonlinear effects to be significant. This is one of the chief reasons why the standard viewpoint postulates dark matter in order to account for galaxy rotation curves.

There is a body of research by Deur, among others, that claims that the above is not the case. This research has been discussed in a number of PF threads. I think it's fair to say that these proposals have not achieved much traction in the wider community, although research along these lines continues.

There is also the MOND viewpoint, which claims, in effect, that GR does not correctly describe the law of gravity for very small "acceleration due to gravity". (Many MOND proponents do not describe their research this way, but that is what it amounts to.)
 
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Thank you so much for taking the tine to answer my questions.
I attempted to understand your insights article "does-gravity-gravitate", however I am not at your level. One actually has to study physics at a graduate level and take classes in General Relativity to understand.
Is professor Alexander Deur mathematics correct? As you know, he is a reasearch physicist in particle physics at Jefferson Labs in Virginia.
 
KurtLudwig said:
Is professor Alexander Deur mathematics correct?
That is an open question. If you search PF for his name you will find multiple threads discussing his work. I am not aware of any other physicist who has confirmed his calculations.
 
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