Comment Re:Wow. (Score 1) 302
Hmm... that's not what I understood from the summary. That is, I didn't understand that the article talked about how galaxies with closer arms rotate faster than galaxies with stretched arms and why.
Instead, what I understood is more like when you stretch your arms, they keep your elbows and hands rotating around you with the same orbital velocity, regardless of this common velocity being faster or slower for the entire body. But since there are no real arms linking the galaxy's elements, the orbital velocity of an object far from the center should be slower than that of a nearer object, I guess making galaxies look like discs instead of stretching arms. Yet, that's not how they look.
The article then tries to explain it with gravity from faraway objects as opposed to dark matter.
I could of course have misunderstood it entirely.