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Spiral direction
Posted: Sun Mar 17, 2013 3:56 pm
by Robinegg
Is the direction of spiral structures in the cosmos evenly distributed between those evolving clockwise and those counterclockwise, or is there a bias in one direction?
Re: Spiral direction
Posted: Sun Mar 17, 2013 4:22 pm
by Case
Robinegg wrote:Is the direction of spiral structures in the cosmos evenly distributed between those evolving clockwise and those counterclockwise, or is there a bias in one direction?
Physics says there shouldn't be a bias.
Initial manual counting suggested there could be a small, but unexplainable bias, though.
The
Galaxy Zoo Project tried to answer this. What was needed was an extensive study on a large number of galaxies by a lot of different people. Even their results seemed to show (a small) bias. Until they made a separate study of the bias: when checking mirrored images of galaxies, the bias was the other way around. It seems
the human mind has a (semi-collective) bias making a decision when close to an "I don't know" situation.
"beads on a string"
Posted: Sun Mar 17, 2013 5:07 pm
by neufer
http://en.wikipedia.org/wiki/Spiral_galaxy#Alignment_of_spin_axis_with_cosmic_voids wrote:
<<Recent results suggest that the orientation of the spin axis of spiral galaxies is not a chance result, but instead they are preferentially aligned along the surface of cosmic voids. That is, spiral galaxies tend to be oriented at a high angle of inclination relative to the large-scale structure of the surroundings. They have been described as lining up like "beads on a string," with their axis of rotation following the filaments around the edges of the voids.>>
http://en.wikipedia.org/wiki/Void_%28astronomy%29 wrote:
<<In astronomy, voids are the vast empty spaces between filaments (the largest-scale structures in the Universe), which contain very few, or no, galaxies. They were first discovered in 1978 during a pioneering study by Stephen Gregory and Laird A. Thompson at the Kitt Peak National Observatory. Voids typically have a diameter of 11 to 150 megaparsecs; particularly large voids, defined by the absence of rich superclusters, are sometimes called "supervoids". Voids located in high-density environments are smaller than voids situated in low-density spaces of the universe. Voids are believed to have been formed by baryon acoustic oscillations in the Big Bang by collapses of mass followed by implosions of the compressed baryonic matter. Starting from initially small anisotropies due to quantum fluctuations in the early Universe, anisotropies grew larger in scale over time. Regions of higher density collapsed more rapidly under gravity, eventually resulting in the large scale foam-like structure or “cosmic web” of voids and filaments seen today.
Voids appear to have a correlation with observed temperature of the Cosmic Microwave Background (CMB) due to the Sachs–Wolfe effect. Colder regions correlate to voids, whereas hotter regions correlate to filaments due to Gravitational redshifting. As the Sachs-Wolfe effect is only significant if the Universe is dominated by radiation or Dark energy, the existence of voids is significant in providing physical evidence for dark energy. >>
Re: Spiral direction
Posted: Sun Mar 17, 2013 7:16 pm
by Chris Peterson
Robinegg wrote:Is the direction of spiral structures in the cosmos evenly distributed between those evolving clockwise and those counterclockwise, or is there a bias in one direction?
There is no such thing as clockwise or counterclockwise with galaxies, as these are determined simply by the direction the object is viewed from. It would be better to ask if there is a bias in terms of inclination. It is hard to tell, as there are local biases (where "local" can be a very large volume).
