[trhway]

"So, if the quasars are in a long filament then the spins of the central black holes will point along the filament."

the filament formation means the matter moving inward toward the virtual "centerline" (the term is used here pretty loosely obviously) of the filament. As this movement isn't perfectly aligned/balanced there is a total nonzero angular moment of the matter kind of orbiting around the "centerline" - the vector of the moment pointing along the "centerline". The bigger the object inside the filament, the more [statistically] expected its angular moment to be aligned with the total angular moment of the filament.

[feider]

what? Can I have this translated "for dummies" also?

[SiVal]

Imagine an airplane at an airshow. It flies past with a smoke generator belching out smoke, leaving a rough trail behind it that churns and deforms. It's roughly a long tube of churning particles.

Now take this shape into space and make it enormously large. All of the particles in this long, stringy, tube-shaped arrangement attract each other gravitationally, so the tube starts to tighten. The particles around the outside of the tube are pulled back toward the other particles in the tube, which generally pulls them toward the centerline of the tube. Of course, each particle will have its own momentum, so if you looked down the centerline of the tube, you'd see some particles heading a little to one side of the centerline, some heading toward the other. Looking down that centerline, you'd see some particles tending to orbit around the center in a clockwise direction, some others going counter-clockwise.

It's very unlikely that there would be the same number of particles going clockwise around the centerline as counter-clockwise. Just randomly, there would very likely be somewhat more particles going one way than the other, so eventually the tightening tube would seem to be rolling around its centerline in the majority direction.

What trhway is saying is that any really big, dense clusters of particles in the tube would probably have roughly the same characteristics as the whole tube they were a part of. The particles rotating around the center of a large, dense cluster of particles in the tube would tend to resemble the rest of the tube statistically, so they would tend to roll in the same direction as the tube itself, meaning the axes of rotation of these big chunks would tend to be parallel with each other and parallel to the centerline of the tube.

[trhway]

>What trhway is saying is that any really big, dense clusters of particles in the tube would probably have roughly the same characteristics as the whole tube they were a part of. The particles rotating around the center of a large, dense cluster of particles in the tube would tend to resemble the rest of the tube statistically, so they would tend to roll in the same direction as the tube itself, meaning the axes of rotation of these big chunks would tend to be parallel with each other and parallel to the centerline of the tube.

yep. Just to add that as those chunks has already clumped close together they are forced to rotate much faster to preserve their share of angular momentum - thus we see rotating quasars on the background of seemingly (in our observation timescale) static filament.

[trhway]

:) imagine say 2 objects in space moving toward each other like 2 cars in the opposite direction lanes. Imagine there is a long metal bar across the road such that these 2 cars hit it simultaneously from their respective directions - the bar will rotate - i.e. the combined system of these 2 cars has angular moment. In space there is no bar, instead there is gravitation - these 2 cars would get clumped together (on the "divider" between the "lanes") due to gravitation pull between them. The resulting clump will rotate as result of the angular moment preservation. Now if we expand the model to billions of billions of rocks and gas clouds which form the filament ... :)