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Simulation in video I linked is not MOND. Dark Matter is postulated due to observations of galaxies in isolation. BUT galaxies are not gravitationally isolated. They gravitationally affected by all the other galaxies in their neighborhood. The video and simulation is pretty straight forward. Dark Matter is simply unnecessary to explain galaxy rotation curves.

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Even if you are correct about the galaxy rotation curves -- which everything I've read and heard leads to me believe is rather unlikely -- those curves are only one of several pieces of evicence that point to the existence of dark matter. The wikipedia page list many of these: https://en.wikipedia.org/wiki/Dark_matter#Observational_evid...

I only mentioned MOND as it is one of the more widely-known plausible alternatives that have been pursued.

And I and the video creators are only claiming dark matter is not needed to explain galaxy rotation curves. Whatever other spaghetti lumped into the need for dark matter, have at it... but galaxy rotation curves are explained quite neatly looking at two things: 1) dark matter was initially postulated and never reexamined because galaxies were observed as gravitationally isolated and 2) when not unnaturally gravitationally isolating galaxies from their neighborhood group, the rotation curves make precisely exact and perfect sense

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