On 01/13/2011 05:19 PM, mix...@bigpond.com wrote: > In reply to Mauro Lacy's message of Thu, 13 Jan 2011 09:23:01 -0300: > Hi, > [snip] >> Let's calculate the acceleration produced by 200 million suns. This is >> doomed to fail because, as we know, galaxies don't obey Newton's >> gravitational law, but just to have an idea: >> a= Fg/msun = G msun*2*10^11/(26000 * 9.4607305e+15)^2 = >> 4.3882998825*10^-10 m/s^2 >> >> Which is two times the centripetal acceleration... if we suppose that >> the central bulge contains half the visible mass, the standard >> calculation will coincide with the observed values for our Sun. But it >> will fail for stars farther from the center, which are also moving at >> 250 km/s. >> >> In the wikipedia entry >> https://secure.wikimedia.org/wikipedia/en/wiki/Milky_Way >> you can see the expected vs. observed galactic rotation curves >> https://secure.wikimedia.org/wikipedia/en/wiki/File:Rotation_curve_%28Milky_Way%29.JPG >> >> And they inf fact coincide in the case of our Sun. >> >> Anyways, any effect smaller than, let's say, 2*10^-11 m/s^2, can be >> safely ignored. > [snip] > I would be interested in a calculation of the strength of the magnetic > attraction/repulsion between the galactic magnetic field and the Solar > magnetic > field, and by how many orders of magnitude it differs.
That can surely be calculated or searched for, and I can attempt it during the weekend. Probably the strengths are too small to produce appreciable accelerations. But what I find most revealing is is the following: I was thinking that the coincidence, in the Sun's case, between the estimated centripetal acceleration(using the centripetal acceleration formula), and the acceleration calculated according to Newton's gravitational formula, is not a mere coincidence. Newton's "universal" gravitational "constant" is "tuned in" to our local environment. That is, G is correlating the amount of visible matter(what we ordinarily call mass and has weight) with the (local) strength of the gravitational field. And is afterwards assuming that correlation to be universal. If we lived near or farther the center of the galaxy, our value for G would be different. An elegant answer is that there's no dark matter, but instead something which interacts with and depends partly on normal matter. Gravity is not a field or force produced by matter, but a velocity field interacting with matter. It depends on matter density(matter density partly defines the local velocity inflow(a velocity field like in a fluid, but hyper dimensional)). That velocity field has (or have had in the past) other causes than matter. Looking at the galaxy rotation curves graph (https://secure.wikimedia.org/wikipedia/en/wiki/File:Rotation_curve_%28Milky_Way%29.JPG) it strikes me as evident that the galaxy is rotating /en masse/. If you look at the blue line(i.e. the observed rotational velocities), the velocity can be thought of as being constant near 200 km/s, with the increases corresponding to the zones of the galaxy arms (i.e. where matter density is greater). So, we have a constant rotational velocity for the whole galactic disc(including empty space), with zones of increased velocity related to increased matter density in those areas. That increased matter density is at the same time the result of an increase of flow velocity, and a cause of it, like in the case of a reinforcing dynamical process. This would explain all the gravitational anomalies as divergences from the accepted value of G. This is, divergences from the relationship between ponderable matter, and the local gravitational field strength in each case. Regards, Mauro
