When galaxies are closer together, they tend to be more spiral. This
indicate to me spirals are result of close encounter of 3d kind.
Imagine 2 basket ball nick each other in space and spin. Of course unlike
basketball, gravity makes it slightly tragect in rather than slight bounce.
Easier to picture randomely distributed galaxy then some single mass like
black hole pass by causing angular momentum, 2nd galaxy work as fine, but
not as easy to picture...

Alternatively, if our visual universe is created by collision of 2 black
holes then resultant energy distribute in chaotic way and some angular
momentum..


"Richard Dickison" wrote in message
...
Why are most galaxies and solar systems 'flat'? If there is a cloud of
dust/gas that starts to coalesce around a localized density in the middle
of
the dust/gas, it seems it would attract from all 3 dimensions equally. But
galaxies and solar systems attract primarily in a single plane. What
happened to all the debris above/below the plane?

I understand there will probably be an unequal distribution of matter
surrounding the central object and there will consequently be a resultant
angular momentum after a while. But that doesn't seem to explain why
there
still isn't debris spiraling in from above/below the primary plane.