Chaos in Galactic Motions ?

[Widdekind]

Imagine simulating the evolution, through time, of the Local Group (say). You create, in computer, several spiral galaxies, and a slew of spheroidals, and evolve them for billions of years. You plot their paths through space & time.

 

Now, imagine re-doing that simulation, starting from the same initial conditions, but "jiggering" all the stars' initial positions, by +/- several light-years, in random directions. Then, re-run the simulation, for the same amount of time.

 

Would varying all the positions, of all the billions of stars comprising a galaxy, by a few light-years, in varying directions, ultimately affect the global, bulk motion, of that galaxy, through space ? If, in one simulation, a galaxy gradually 'hooked to the left' over billions of years, would such 'slight' stellar adjustments make their galaxy 'go straight', or 'hook right', instead ??

 

If you were trying to feed actual telescope observations, into a super-simulation, to forecast the far future of the Local Group, how much could measurement errors actually affect the results ??

[steevey]

Most of the stars in the galaxy are usually above several light years away from each other anyway. And since the direction is random, some stars and Magellanic clouds would be closer to others and probably still form a super-massive black hole for the other matter in the region to circle around.

Edited February 6, 2011 by steevey

[Schrödinger's hat]

Most complex systems are chaotic to some degree. If you redistributed the center of mass (or even made motions that moved a large cluster of stars), then it was ejected during one interaction it could later nudge a galaxy into a slightly different course, and so on.

But remember, we have to think of the scale of these things, individual stars to a galaxies are like raindrops falling on a mountain range, so many and so tiny that you'd have to wait a very very long time for any fluctuations to add up. And hope that the alterations you made were not too far into the stable solutions and negative feedback loops.

 

Also, it would depend on how early you made the changes. If galaxies were still forming you'd be able to alter a lot. Now, not as easily