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August 15, 2017 at 4:11 am
The answer to the first part of the problem seems to be that a natural cloud of space dust cannot and must not, by the laws of physics aggregate into a disc.
Natural would be a cloud of dust existing as it always has just drifting along in space stationary as Ragnar says.
Of course this is itself physically difficult [impossible to conceive].
The answer lies in two aspects.
One billions of years ago when the very large original and their second and third, tenth offspring exploded scattering the dust outwards not to return. Escape velocity.
Combined with an expanding universe? theoretically each particle would be most unlikely to congeal with other particles.
Gravity would however tend to draw some adjacent particles into files and rows of outward extending streaks so one can imagine over time streaks/streams of related matter traveling semi adjacent to each other.
Time is the factor here.
The universe was a lot smaller and these particles were impeded by the other stars and exploded star materials ending up in swirls around the other stars til they too exploded and clumping together with the other debris and interacting with the debris from the newer exploding stars.
These of course included heavy metal particles with more gravitational attraction.
It is not the gravitational attraction that causes the formation of discs and protostars. It is the left over differential movements of the particles that have come from different stars in different directions being forced into a mass that is assumed to all have the same angular momentum but doesn’t.
The bits that travel in opposite directions collide lose velocity and become subject to the effect of their gravity and start pulling everything in that was previously happily moving in unison with its own debris pattern [and not coming together]
The problem is somewhat similar to the discussions on Carbonate build up in the crust of the earth. On massive time scales we have a crust impregnated with billions of tons of inorganic matter that was once organic, now unrecognizable.
The universe is at least 4 1/2 times older than the earth with all that extra time to fashion the stars we see today.
Thanks for the interesting post. I hope my contribution is not perceived as token.