Learn to quote.
[Thomas 'PointedEars' Lahn wrote: ]
Post by john
“The velocity of stars of a spiral galaxy is approximately constant at the
same distance from the galactic center. This is why one can produce
rotation curves, and finds that, surprisingly, the rotation curves of spiral
galaxies are peculiar; as if there were much more mass than the
electromagnetically interacting, baryonic matter. This is considered as one
piece of evidence for Dark Matter. ”
You have that exactly backwards.
Not at all. You have no clue.
The discovery of the rotation curves precipitated a wild scramble to save
current gravity theory. Dark Matter is the potential Saviour,
but It hasn’t quite been found yet.
It has not been *detected*, i.e. observed *directly*, yet. Its effects can
be seen all over the place, though, from galactic rotation curves (which
would be Keplerian if there were no dark matter¹) to gravitational lensing
to universal expansion (which would be much faster if there were not dark
matter) to universal curvature (which would be greater if there were not
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