John15 said:
I realize the BB was not an explosion in space but as everything is apparently moving away from everything else presumably in a linear direction then something must have started things spinning from the beginning, pure linear motion would not allow anything to form in the universe.
There are many things wrong with your notions.One problem is that the Hubble expansion is a very large scale phenomenon. The attractive nature of gravitation dominates over the expansion at shorter distances, where "shorter distances" means the size of a cluster of galaxies. Gravitation dominates over the expansion at the scale of the formation of a single galaxy, and complete dominates at the scale of the formation of a star.
In short, you are ignoring gravity. The expansion has little, if any, effect on small scale structures such as galaxies. A star system is a tiny, tiny structure compared to the scale at which expansion dominates over gravitation.
Another problem is that just because the net angular momentum of a collection of objects is zero does not mean that the angular momentum of each object is zero. So where does this angular momentum come from? One answer is gravitation. Because gravitation is an inverse square force, two bodies interacting gravitationally can exert torques on one another. We see this right here on the Earth in the oceanic tides and in the 26,000 year lunisolar precession of the Earth's rotation. Both phenomena are caused by tidal torques. These tidal torques, aka gravity gradient torques, also act on larger scale objects in space such as clouds of gas. Tidal torques spin up clouds of gas of all sizes, from the huge primordial clouds that eventually became our galaxies down to the smaller clouds from which stars form.
I posted the question because I read somewhere that there is a problem in accounting for all angular momentum seen.
Yes, there's a problem, and I've alluded to this problem in my earlier posts. This just means that there are opportunities galore for future PhD candidates to write a neat thesis. It's a devil in the details kind of problem. The basic mechanisms such as tidal torques are well-understood and are well-observed. There are various conjectured mechanisms to address the angular momentum problem, but these remain conjectural at this point. We need better telescopes and better computer models to fully resolve these open questions.The nice, wrapped up in a pretty box with a ribbon and and bow picture you get in high school and even undergraduate science classes is never quite right. There would be no point in getting a PhD if a science was fully understood and comprehensible at the undergraduate level. Fortunately, there is not one branch of science that is fully understood. There are lots and lots of opportunities for PhD candidates of all sorts to extend their selected field.
There is also the problem with Venus as it spins in the opposite direction to other planets.
One answer is a collision. A collision is not needed, however. All that is needed are tidal torques from the Sun and Jupiter, plus a good dose of chaos theory. This is a separate issue, however. Let's keep this thread on one subject.
I can see how the origional gas/dust cloud of the solar system can orbit the sun but I don't see how the coming together of the same causing planetary spin unless all particles were already spinning in the same direction otherwise spin of one would tend to cancel spin of another.
That isn't needed. The rotation of the first three gas giants most likely resulted from planetary migration. Once the protoplanet has formed, it orbits at a slightly greater speed than does the surrounding gas. This is a simple consequence of orbital mechanics. The protoplanet races through the cloud, gathering material and losing linear momentum as it goes. This clears a path through the cloud along the protoplanets orbit and also causes the protoplanet to migrate sunward into a new source of yet-ungobbled (and hence more dense) material. That gradient in density creates a torque on the protoplanet as it gobbles up new material. Think of a snowball rolling downhill, gathering material and angular momentum as it goes.
The same applies to the inner planets to a less extent. Whether it fully explains the rotation rates of the inner planets is an open question.
I have also read that the ignition of the sun would cause a shockwave through the dust cloud which would cause linear motion away from the sun which would also have to be countered.
When the Sun ignited it blew the left over gas out of the solar system. The stuff that had already accumulated into clumps, not so much. Radiation pressure is proportional to area (length squared), mass is proportional to volume (length cubed). There's a cube-square law relation going on here that makes small objects much more susceptible to radiation pressure than are larger objects.
