On 22 Feb, 13:40, "Robert Karl Stonjek"
wrote:


Thanks, Ian,
The simulations are a little to big but the paper search is more
interesting. *For instance in The method of Galactic Rotationhttp://adsabs.harvard.edu/abs/1996A&AS..118...59J
the authors assume an instant propagation of gravity and the gravitational
pull of the galactic arm itself appears to be left out altogether.

There is always the question about the validity of assumptions.
Instantanious travekl for gravity can be defended on the basis that
the errors in that approximation are of the order of rotation
velocities relative to c.

Now the Sun is travelling at 600km/s c = 300,000km/s. Hence the
instantaneous travel of gravity can be justified. The velocities of
the stars relative to each other are lower still.

What is in fact more serious is assumptions about "dark matter".


- Ian Parker