webolife wrote:Galaxy rotation has been "anomalous" for several decades, this is not really anything new. What I think readers here need to understand is that measures/data of galactic rotation are another product of assumptions about the meaning of redshift. What astronomers have observed since the 80s is a "flat" redshift gradient as you observe the light from galactic matter at increasing distances from the core. The relative redshift should decrease steadily as it's observed on the side of the galaxy turning away from us, in accordance with both NM and the premise of Doppler/recessional redshift; likewise the relative blueshift should decrease in the same manner on the side of the galaxy turning toward us. But what is seen is that this relative spectral redshift gradient is mostly "flat", ie. it changes little with increased radius. It is quite possible that NM is intact, but that the redshift is being misinterpreted, as in other cases that have been well documented and explained by the late Halton Arp, et. al. Perhaps the general "ionization" of stars more distant from the "home" galactic core increases in a way hitherto unexplored?
Yet that still leaves us with a problem, doesn’t it? While you are absolutely right that there must be an additional source of redshift, other than Doppler redshift, if we merely add a radially symmetric source of redshift, we still are stuck. The way Don modeled galactic rotation, was To match it to the relative redshifts we see on one side of a galaxy, compared to the other. In other words, besides any “intrinsic” redshift a galaxy may show, we still need the Doppler redshifts of one side of the galaxy compared to the other. If you merely add extra redshift (or blueshift), to both sides of an edge on galaxy, it won’t explain rotation.
The only way to explain rotation we see, using Don’s model, is to say the Doppler redshift variation we see across a galaxy, is a reflection of the absolute rotation rate of the galaxy. Then any intrinsic redshift, must appear on top of that, and across the galaxy as a whole. Then that forces us to address next, why the arms don’t wind up. Since any differential rotation of a galaxy (even as Don models), still leaves us with the problem of why spiral arms don’t wind up over time.
The solution, is merely to put these ideas together: Galaxies rotate as Don modeled, but the spiral arm structure we see is not a reflection of that rotation. Current must flow along the arms, as Wal Thornhill stressed early on.
So maybe the gas, dust, and or stars, follow a rotation curve as Don modeled, but the current is out radially across the galaxy.
To avoid confusion, just pair it to what we see on the solar system scale. Comets may orbit the sun in an elliptical orbit, but the cometary tail streams outward radially from the sun. In other words, the most important lesson, is that we must divorce the orbital path of stars around the galaxy, from the shape of this discharge path (spiral arms).
Am I helping here: Don’s model, just like the mainstream’s does show faster rotation for stars near galactic center. Only in Don’s model, rotation falls of more slowly as we move outward from galactic center. Therefore we don’t need dark matter. Good, so far. But any rotation, other than total solid body rotation (as if the galaxy turned like a solid disk), will still leave us with the question of why arms don’t either wind up, or unwind, over time. So, the arm shape, can’t be linked to rotation, even in Don’s model. We really have to stress the idea that current flow is along the arms, while the path of stars must be more azimuthal around galactic center. Did that help, or make it worse?