>"The new VLT results indicate that the rotation axes of the quasars tend to be parallel to the large-scale structures in which they find themselves. So, if the quasars are in a long filament then the spins of the central black holes will point along the filament."
Though I have no real idea what I'm talking about...
This feels intuitive to my mental picture of the universe.
The description of this large scale structure and the expansion of the universe has always put me in mind of watching the patterns form and reform from drips in a soapy sink or an elastic fabric being pulled apart.
In both cases, you end up with these big expanses bordered by dense stringy areas. That the motion of the stuff that snaps / shears / collapses or whatever into these strings and knots would be aligned seems perfectly logical.
Conservation of angular momentum. I don't see this as all that shocking. If you consider that the universe is growing (or at least it appears to be and to the best of our knowledge), and that therefore at some point the matter that now comprises these quasars was quite probably part of a single coherent system, say, an earlier galaxy, which would have had angular momentum - all this is showing is the angular momentum of the structure which birthed the quasars. Which is neat.
Simple version: imagine you have a long pole which is spinning, fast. Then imagine a ninja comes in and slices the pole up, perpendicular to its axis, so you've got 20 short poles. The 20 short poles continue to spin on the same axis as the original long pole. If those poles are in the vacuum of space with nothing slowing them down, they will continue to spin in the same way for a very, very long time. They might wobble a bit (precession), which explains why the poles aren't all perfectly aligned in this data.
Our intuition does a very poor job of answering questions like this (well, almost any questions, really) and we can spend a lot of time fooling ourselves that the way the universe actually is "makes sense" in some intuitive way. It doesn't. If it did, we'd have had correct physics in 1687 BCE instead of 1687 CE.
One way to test this is to ask yourself what your intuition tells you before you know the answer. You'll mostly get it wrong, unless you have formal training in the field. Intuitive "explanations" are only good after the fact, and even after the fact can be misleading and problematic, as the one you bring up here is.
The universe as a whole (very probably) has zero angular momentum. There are consequences on the large scale if this is not the case that we'd probably have detected by now. So early star formation, including quasar formation, happened in a hot zero-momentum gas cloud that filled the expanding universe. That is the structure that birthed the quasars. That means that while there may well have been local eddies, there was not any overall rotation to the gas. So why would quasars that formed in distant parts of that gas have their axes aligned in the same direction?
Short version: your mental model of the early universe is not accurate, so your intuitive explanation doesn't actually explain the phenomenon under study. Simply because it "makes sense" of the data does not make it useful. In particular, you've assumed a counter-factual.
The reason why cosmologists are surprised by these results is because they have a better understanding of the early universe, and know that there is no known mechanism to align the rotational axes of these objects. They are now wondering what that mechanism might be. Global angular momentum is one possibility, but it is far, far down on the list because it is contradicted by a lot of other data.
> Our intuition does a very poor job of answering questions like this (well, almost any questions, really) and we can spend a lot of time fooling ourselves that the way the universe actually is "makes sense" in some intuitive way. It doesn't. If it did, we'd have had correct physics in 1687 BCE instead of 1687 CE.
> Conservation of angular momentum. I don't see this as all that shocking.
What is fascinating is that the angular momentum seems to be roughly aligned with the underlying "membranes", as if the voids themselves are actually expanding.
> A correlation between the orientation of quasars and the structure they belong to is an important prediction of numerical models of evolution of our Universe.
This was predicted so there must be some understanding of how it works. Doesn't seem that spooky.
No, it's not. Spooky action at a distance refers to phenomena arising at the quantum level. The scale difference between that and alignment of the rotations of quasars is getting near the largest observable scale difference there can be. Which, itself, is kinda satisfying :).
The spookiness here is of similar nature as the spookiness how the eurasian continental plate seems to fit snugly with the american one although they are now quite far apart - i.e. we should be able to figure out which past events led to the current configuration.
I would call this result 'really cool' rather than 'spooky' but neither of those are very specific terms ;)
Out of "93 quasars", "19 of them found a significantly polarized signal." "Results indicate that the rotation axes of the quasars tend to be parallel to the large-scale structures in which they find themselves."
Do quasars that aren't parallel to their large-scale structures not have a significantly polarized signal? Maybe interference from the structure or a weaker signal because of their alignment?
If we wind the clock back far enough couldn't we explain this if the original matter that went on to form the black holes originated from blobs of matter that were affected by the same local forces? Then we just wait long enough and things that were next to each other in the distant past now reside long the dark mater filaments? Given the angular momentum of these suckers I'd guess that it is pretty hard to significantly change their axis of rotation even over a couple billion years.
“The first odd thing we noticed was that some of the quasars’ rotation axes were aligned with each other — despite the fact that these quasars are separated by billions of light-years,” said Hutsemékers.
This seems like it might be a breakthrough result.
"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.
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.
:) 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 ... :)
Readit News
Though I have no real idea what I'm talking about...
This feels intuitive to my mental picture of the universe.
The description of this large scale structure and the expansion of the universe has always put me in mind of watching the patterns form and reform from drips in a soapy sink or an elastic fabric being pulled apart.
In both cases, you end up with these big expanses bordered by dense stringy areas. That the motion of the stuff that snaps / shears / collapses or whatever into these strings and knots would be aligned seems perfectly logical.
Simple version: imagine you have a long pole which is spinning, fast. Then imagine a ninja comes in and slices the pole up, perpendicular to its axis, so you've got 20 short poles. The 20 short poles continue to spin on the same axis as the original long pole. If those poles are in the vacuum of space with nothing slowing them down, they will continue to spin in the same way for a very, very long time. They might wobble a bit (precession), which explains why the poles aren't all perfectly aligned in this data.
One way to test this is to ask yourself what your intuition tells you before you know the answer. You'll mostly get it wrong, unless you have formal training in the field. Intuitive "explanations" are only good after the fact, and even after the fact can be misleading and problematic, as the one you bring up here is.
The universe as a whole (very probably) has zero angular momentum. There are consequences on the large scale if this is not the case that we'd probably have detected by now. So early star formation, including quasar formation, happened in a hot zero-momentum gas cloud that filled the expanding universe. That is the structure that birthed the quasars. That means that while there may well have been local eddies, there was not any overall rotation to the gas. So why would quasars that formed in distant parts of that gas have their axes aligned in the same direction?
Short version: your mental model of the early universe is not accurate, so your intuitive explanation doesn't actually explain the phenomenon under study. Simply because it "makes sense" of the data does not make it useful. In particular, you've assumed a counter-factual.
The reason why cosmologists are surprised by these results is because they have a better understanding of the early universe, and know that there is no known mechanism to align the rotational axes of these objects. They are now wondering what that mechanism might be. Global angular momentum is one possibility, but it is far, far down on the list because it is contradicted by a lot of other data.
I do have formal training in the field, if a masters in physics counts, with a specialisation in cosmology and astrophysics.
My thesis was oriented around computational simulations of the early universe, using fluid dynamics.
This is excellent.
Relative to what? Or do you mean the observable universe relative to the CMB?
Why would you expect the ninja to do this? Why would you expect large-scale structures of the universe to form parallel to the quasars' axes?
As far as we can tell, the alignment of planetary systems in the Milky Way are random.[1]
[1] http://astronomy.stackexchange.com/questions/546/why-is-our-...
What is fascinating is that the angular momentum seems to be roughly aligned with the underlying "membranes", as if the voids themselves are actually expanding.
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This was predicted so there must be some understanding of how it works. Doesn't seem that spooky.
The spookiness here is of similar nature as the spookiness how the eurasian continental plate seems to fit snugly with the american one although they are now quite far apart - i.e. we should be able to figure out which past events led to the current configuration.
I would call this result 'really cool' rather than 'spooky' but neither of those are very specific terms ;)
Do quasars that aren't parallel to their large-scale structures not have a significantly polarized signal? Maybe interference from the structure or a weaker signal because of their alignment?
This seems like it might be a breakthrough result.
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.
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.
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