This is basically correct. As long as a cloud is in the form of gas, it is relatively easy for it to lose energy (by, for example, viscous forces), but not angular momentum. As it loses energy, it collapses (see a recent thread on the https://www.physicsforums.com/showthread.php?t=121847"), and as it collapses, the faster it rotates. The end result is a disk. Examples of this are quasar accretion disks, protoplanetary disks, and spiral galaxies (where the disk stars formed from gas that had already collapsed to a disk).tony873004 said:The rotation of a spherical cloud about an axis prevents collapse towards the axis, but does not prevent the cloud from collapsing parallel to the axis of rotation, so it flattens into a disk.
True :)In the same way, a spinning ice skater who pulls her arms inwards spins faster, but does not suddenly acquire a tilt.