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Galaxy filaments are "amongst the largest known cosmic structures in the Universe. They [...] form the boundaries between large voids in the Universe."

As their name suggests, filaments are essentially 1-dimensional objects (significantly longer and wider than thick, and significantly longer than wide), but how can such objects be the (very) boundaries of 3-dimensional voids?

In the same Wikipedia article, "supercluster complexes", "great walls", and "great attractors" are proposed as synonyms for "filaments" which suggest other dimensions ($d$):

  • unspecified for "complexes"
  • $d=2$ for "walls"
  • fractal ($1 < d < 2$ or $2 < d < 3$) for "attractors"

What is/can be said about the dimension of these cosmic objects?

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    $\begingroup$ A complex is a generic structure of superclusters. So d~1 is fine. And it says "great walls" not "walls". For a wall, d=2. But picture the Great Wall of China. compare the length to the height and the height to the width. d~1. $\endgroup$ – Jim May 27 '14 at 21:04
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    $\begingroup$ Picture an array of intersecting bubbles. Where each intersection occurs, it forms a ring. If a center bubble intersects bubbles on all sides, then it has many of these rings. While the space between the rings is void, the positioning of all of them roughly define the center of the center bubble. Similarly, the galactic filaments do not form continuous boundaries, but they roughly make a "wire-mesh" defining the shapes of large voids $\endgroup$ – Jim May 27 '14 at 21:08
  • $\begingroup$ For a generic structure of superclusters I would assume d~3: they are somehow arranged. $\endgroup$ – Hans-Peter Stricker May 31 '14 at 23:48
  • $\begingroup$ This is far too half-baked to comprise an answer, but, given the resemblance between the filaments and an inverted version of a planetary atmosphere containing numerous vortices, you might want to look at cosmologies that require a prevalent (however marginally) direction of rotation, together with sequential reductions in that rotation's scales, such as Poplawski's cosmology with torsion and, in particular, his 2011 "Matter-antimatter asymmetry and dark matter from torsion", whose math is far beyond me. $\endgroup$ – Edouard Jun 5 '19 at 16:35
  • $\begingroup$ I've got to add that I really like Jim's observations, as I'd drafted some notes a few years ago describing the universe as "a cage of filaments". Those observations seem disparate from my own posting, although meteorologists do refer to the structures that produce the smallest vortices as "cells". $\endgroup$ – Edouard Jun 5 '19 at 16:44

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