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The paper I was referring to is from 2020. She brings up MOND because she's explaining the alternatives to dark matter, and EFE is (as far as I know) an extensi

The paper I was referring to is from 2020. She brings up MOND because she's explaining the alternatives to dark matter, and EFE is (as far as I know) an extension to MOND that was postulated Milgrom back in 1983.

Maursault 4y ago
Then I may have incorrectly assumed the video I linked explains EFE, and I'm not sure if the theory described in the video has a name, but it uses what I would call tidal effect to explain galaxy rotation curves, which sounded to me a lot like: > where the anomaly in the rotation of galaxies (which is what dark matter is needed to explain) can be explained by the gravitational pull of other nearby galaxies. Is it possible producers of the 2013 video I linked above were unaware of EFE Theory (esp. if it appeared in 1983)? I do not see MOND necessary anywhere in the video I linked, personally think MOND is bollocks, but the narrator seems to have self-referred to the theory described as External Gravitational Effect (I think) at least once. I have to watch it again, it's very boring so I may have missed reference to EFE, or it may be unrelated and just similar, or the same and described from different perspectives, but on the surface, they appear the same. I've just never heard of EFE, not that surprising, but I don't really know for sure if it is the same as what's in that video I harvested from a Slashdot comment about 6 years ago.
- atombender 4y ago
  I don't know what that video is describing, relative to EFE. The paper [1] abstract describes EFE and their findings this way: Theories of modified gravity generically violate the strong equivalence principle, so that the internal dynamics of a self-gravitating system in free fall depends on the strength of the external gravitational field (the external field effect). We fit rotation curves (RCs) from the SPARC database with a model inspired by Milgromian dynamics (MOND), which relates the outer shape of a RC to the external Newtonian field from the large-scale baryonic matter distribution through a dimensionless parameter eN. We obtain a >4σ statistical detection of the external field effect (i.e. eN>0 on average), confirming previous results. We then locate the SPARC galaxies in the cosmic web of the nearby Universe and find a striking contrast in the fitted eN {values} for galaxies in underdense versus overdense regions. Galaxies in an underdense region between 22 and 45 Mpc from the celestial axis in the northern sky have RC fits consistent with eN≃0, while those in overdense regions adjacent to the CfA2 great wall and the Perseus-Pisces supercluster return eN that are a factor of two larger than the median for SPARC galaxies. [...] [1] https://arxiv.org/abs/2109.04745 https://arxiv.org/abs/2109.04745

Maursault 4y ago

Then I may have incorrectly assumed the video I linked explains EFE, and I'm not sure if the theory described in the video has a name, but it uses what I would call tidal effect to explain galaxy rotation curves, which sounded to me a lot like: > where the anomaly in the rotation of galaxies (which is what dark matter is needed to explain) can be explained by the gravitational pull of other nearby galaxies. Is it possible producers of the 2013 video I linked above were unaware of EFE Theory (esp. if it appeared in 1983)? I do not see MOND necessary anywhere in the video I linked, personally think MOND is bollocks, but the narrator seems to have self-referred to the theory described as External Gravitational Effect (I think) at least once. I have to watch it again, it's very boring so I may have missed reference to EFE, or it may be unrelated and just similar, or the same and described from different perspectives, but on the surface, they appear the same. I've just never heard of EFE, not that surprising, but I don't really know for sure if it is the same as what's in that video I harvested from a Slashdot comment about 6 years ago.

atombender 4y ago
I don't know what that video is describing, relative to EFE. The paper [1] abstract describes EFE and their findings this way: Theories of modified gravity generically violate the strong equivalence principle, so that the internal dynamics of a self-gravitating system in free fall depends on the strength of the external gravitational field (the external field effect). We fit rotation curves (RCs) from the SPARC database with a model inspired by Milgromian dynamics (MOND), which relates the outer shape of a RC to the external Newtonian field from the large-scale baryonic matter distribution through a dimensionless parameter eN. We obtain a >4σ statistical detection of the external field effect (i.e. eN>0 on average), confirming previous results. We then locate the SPARC galaxies in the cosmic web of the nearby Universe and find a striking contrast in the fitted eN {values} for galaxies in underdense versus overdense regions. Galaxies in an underdense region between 22 and 45 Mpc from the celestial axis in the northern sky have RC fits consistent with eN≃0, while those in overdense regions adjacent to the CfA2 great wall and the Perseus-Pisces supercluster return eN that are a factor of two larger than the median for SPARC galaxies. [...] [1] https://arxiv.org/abs/2109.04745 https://arxiv.org/abs/2109.04745