Edmund Storms writes:
"I ask how a structure can form when the time needed for one part to sense the characteristics of another part takes millions of years to be communicated? How does a star at one side of a galaxy know that its gravity and momentum are being exactly balanced by a star on the other side when this information takes a million years to pass between the two stars."
My guess is that the structure is formed when the stars are close together at the center of the galaxy. The shape usually remains as it was when they drift apart, because nothing disrupts it. In some cases, galaxies have been disrupted by collisions with other galaxies, I believe.
Galaxies group together to form even larger structures. Presumably this structure reflects conditions soon after the Big Bang, when everything was close together.
- Jed
