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DaveC426913

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- There was a long thread around here (which I can no longer find) about DM being explained by gravitomagnetic effects. Is there a 25 words or less explanation?

I was reading a thread on my phone that was reviewing a paper about DM being explainable by gravitomagnetic effects. Now I can't find it in any search. It was on its fourth page - so at least 80 posts over at least two years.

Anyway, what I wanted to ask was for a description that a layperson might be able to give another layperson about DM.

My tentative conclusion was that:

DM is (so this paper claims) essentially a faulty assumption in how gravity in a spatially-extended object such as a galaxy ought to behave in a Newtonian model. i.e. the 1/r^2 formula is a good approximation in other cases but, here, it just does not apply. When the gravity curve is calculated using GR, it does not work out so simply as 1/r^2, - it tends to level off to a plateau near the edges of such an object. That's just The Way Gravity Works in GR. I also got the impression that an exact solution using GR formulae is impractical, which may be why this solution has been elusive.

Am I close enough for horseshoes and hand grenades?

Anyway, what I wanted to ask was for a description that a layperson might be able to give another layperson about DM.

My tentative conclusion was that:

DM is (so this paper claims) essentially a faulty assumption in how gravity in a spatially-extended object such as a galaxy ought to behave in a Newtonian model. i.e. the 1/r^2 formula is a good approximation in other cases but, here, it just does not apply. When the gravity curve is calculated using GR, it does not work out so simply as 1/r^2, - it tends to level off to a plateau near the edges of such an object. That's just The Way Gravity Works in GR. I also got the impression that an exact solution using GR formulae is impractical, which may be why this solution has been elusive.

Am I close enough for horseshoes and hand grenades?

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