by Chris Peterson » Tue Jul 17, 2012 3:46 pm
Boomer12k wrote:Two...Dark Matter is supposed to be what makes a galaxy appear to rotate as a single unit..as the Gravity is supposed to be very much beyond the mere edge of a galaxy, and caused by 90% dark matter, (that you cannot detect, so far)...as discovered by Carolyn Shoemaker, (she was examining the spectroscopy of galaxies)...
It was Vera Rubin, not Carolyn Shoemaker, who first noted the peculiarities in galactic rotation curves that were suggestive of dark matter halos (dark matter itself had already been inferred from earlier observations of the motions of galaxies in clusters).
Also we bob up and down in the galaxy, (gravity wave?), as on Dec. 21st, 2012 we are going to cross the galactic equator.
We don't bob up and down, but rather, orbit on a plane slightly inclined to the nominal galactic plane. We won't be on the galactic equator on Dec 21, however.
Three...The simulation does not run out of material...more and more material seems to just generate and fall into the galaxy, was Fred Hoyle correct?
No, Hoyle was wrong. No new material is being created in this simulation, it's just falling in from outside the volume that is being rendered. The simulation correctly considers that the Universe is bigger than just the region visualized.
--- I am assuming that the simulation is much larger than just this one area. (As I see other material go by)...But in the real universe, in our own galactic area, while we do have smaller satellite galaxies and such, I don't see them coming in and joining like cotton candy, at the edges like it appears to be here...our galaxy seems more...constant....I think is the word I am looking for...we don't see "extra galactic material" falling into M31, from the sides, for instance...maybe it just represents dust and gas, and not star formation...lot of things the article does not explain, but hey, pressed for space, I guess.
This is a simple simulation in some respects. It's just modeling gas and allowing stars to form from the gas. I don't think the elemental evolution of the galaxy is being considered at all- there's nothing here but hydrogen and maybe helium. No dust, no metals. I'm not at all sure this doesn't reasonably simulate how our galaxy formed, as well. The small cluster we're a part of strongly suggests a period of infall very like what the simulation shows.
[quote="Boomer12k"]Two...Dark Matter is supposed to be what makes a galaxy appear to rotate as a single unit..as the Gravity is supposed to be very much beyond the mere edge of a galaxy, and caused by 90% dark matter, (that you cannot detect, so far)...as discovered by Carolyn Shoemaker, (she was examining the spectroscopy of galaxies)...[/quote]
It was Vera Rubin, not Carolyn Shoemaker, who first noted the peculiarities in galactic rotation curves that were suggestive of dark matter halos (dark matter itself had already been inferred from earlier observations of the motions of galaxies in clusters).
[quote]Also we bob up and down in the galaxy, (gravity wave?), as on Dec. 21st, 2012 we are going to cross the galactic equator.[/quote]
We don't bob up and down, but rather, orbit on a plane slightly inclined to the nominal galactic plane. We won't be on the galactic equator on Dec 21, however.
[quote]Three...The simulation does not run out of material...more and more material seems to just generate and fall into the galaxy, was Fred Hoyle correct?[/quote]
No, Hoyle was wrong. No new material is being created in this simulation, it's just falling in from outside the volume that is being rendered. The simulation correctly considers that the Universe is bigger than just the region visualized.
[quote] --- I am assuming that the simulation is much larger than just this one area. (As I see other material go by)...But in the real universe, in our own galactic area, while we do have smaller satellite galaxies and such, I don't see them coming in and joining like cotton candy, at the edges like it appears to be here...our galaxy seems more...constant....I think is the word I am looking for...we don't see "extra galactic material" falling into M31, from the sides, for instance...maybe it just represents dust and gas, and not star formation...lot of things the article does not explain, but hey, pressed for space, I guess.[/quote]
This is a simple simulation in some respects. It's just modeling gas and allowing stars to form from the gas. I don't think the elemental evolution of the galaxy is being considered at all- there's nothing here but hydrogen and maybe helium. No dust, no metals. I'm not at all sure this doesn't reasonably simulate how our galaxy formed, as well. The small cluster we're a part of strongly suggests a period of infall very like what the simulation shows.