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New Scientist article....
Or is it a cosmic crystal?
American Institute of Physics article....
Axis of evil' a cause for cosmic concern
Some believe it is just a figment of overactive imaginations. But evidence is growing that the so-called "axis of evil" - a pattern apparently imprinted on the radiation left behind by the big bang - may be real, posing a threat to standard cosmology.
According to the standard model, the universe is isotropic, or much the same everywhere. However, in 2005, Kate Land and João Magueijo of Imperial College London noticed a curious pattern in the map of the cosmic microwave background (CMB) created by NASA's WMAP satellite. It seemed to show that some hot and cold spots in the CMB are not distributed randomly, as expected, but are aligned along what Magueijo dubbed the axis of evil.
Some astronomers have suggested straightforward explanations for the axis, such as problems with WMAP's instruments or distortions caused by a nearby supercluster (New Scientist, 22 October 2005, p 19).
Others doubt the pattern's very existence. "There's still a fair bit of controversy about whether there's even something there that needs to be explained," says WMAP scientist Gary Hinshaw of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Now, two independent studies seem to confirm that it does exist. Damien Hutsemékers of the University of Liège in Belgium analysed the polarisation of light from 355 quasars and found that as the quasars get near the axis, the polarisation becomes more ordered than expected. Taken together, the polarisation angles from the quasars seem to corkscrew around the axis.
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The quasar finding has support from another study, however. Michael Longo of the University of Michigan in Ann Arbor analysed 1660 spiral galaxies from the Sloan Digital Sky Survey and found that the axes of rotation of most galaxies appear to line up with the axis of evil
According to Longo, the probability of this happening by chance is less than 0.4 per cent. "This suggests the axis is real, and not simply an error in the WMAP data," he says.
Land, now at the University of Oxford, thinks Longo must rule out other reasons for why the spirals are aligned the way they are. For instance, neighbouring galaxies could have formed from the same rotating dust cloud, giving them similar orientations, she says. "But if he is correct, then this is really exciting, not only as independent confirmation of the axis, but because it'll help us understand what may have created it," she says.
One way to create the axis was presented by Contaldi at a conference on outstanding questions in cosmology at Imperial College last month. The universe is thought to be isotropic because the early universe went through a period of exponential expansion known as inflation, smoothing out any unevenness. Contaldi and his colleagues Emir Gümrükçüoğlu and Marco Peloso at the University of Minnesota, in Minneapolis, modified inflation to allow the universe to expand more in one direction. "Provided inflation stops at a relatively early point, this would leave traces of the early [unevenness] in the form of the axis of evil," he says.
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Some believe it is just a figment of overactive imaginations. But evidence is growing that the so-called "axis of evil" - a pattern apparently imprinted on the radiation left behind by the big bang - may be real, posing a threat to standard cosmology.
According to the standard model, the universe is isotropic, or much the same everywhere. However, in 2005, Kate Land and João Magueijo of Imperial College London noticed a curious pattern in the map of the cosmic microwave background (CMB) created by NASA's WMAP satellite. It seemed to show that some hot and cold spots in the CMB are not distributed randomly, as expected, but are aligned along what Magueijo dubbed the axis of evil.
Some astronomers have suggested straightforward explanations for the axis, such as problems with WMAP's instruments or distortions caused by a nearby supercluster (New Scientist, 22 October 2005, p 19).
Others doubt the pattern's very existence. "There's still a fair bit of controversy about whether there's even something there that needs to be explained," says WMAP scientist Gary Hinshaw of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Now, two independent studies seem to confirm that it does exist. Damien Hutsemékers of the University of Liège in Belgium analysed the polarisation of light from 355 quasars and found that as the quasars get near the axis, the polarisation becomes more ordered than expected. Taken together, the polarisation angles from the quasars seem to corkscrew around the axis.
>
The quasar finding has support from another study, however. Michael Longo of the University of Michigan in Ann Arbor analysed 1660 spiral galaxies from the Sloan Digital Sky Survey and found that the axes of rotation of most galaxies appear to line up with the axis of evil
According to Longo, the probability of this happening by chance is less than 0.4 per cent. "This suggests the axis is real, and not simply an error in the WMAP data," he says.
Land, now at the University of Oxford, thinks Longo must rule out other reasons for why the spirals are aligned the way they are. For instance, neighbouring galaxies could have formed from the same rotating dust cloud, giving them similar orientations, she says. "But if he is correct, then this is really exciting, not only as independent confirmation of the axis, but because it'll help us understand what may have created it," she says.
One way to create the axis was presented by Contaldi at a conference on outstanding questions in cosmology at Imperial College last month. The universe is thought to be isotropic because the early universe went through a period of exponential expansion known as inflation, smoothing out any unevenness. Contaldi and his colleagues Emir Gümrükçüoğlu and Marco Peloso at the University of Minnesota, in Minneapolis, modified inflation to allow the universe to expand more in one direction. "Provided inflation stops at a relatively early point, this would leave traces of the early [unevenness] in the form of the axis of evil," he says.
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American Institute of Physics article....
In the cosmos, there are many galaxies that emit so-called "electromagnetic synchrotron radiation.'' This radiation is highly plane-polarized, which means that its electric field oscillates predominantly within a plane, called the polarization plane of the radiation. In their journey through the cosmic expanse, these plane-polarized waves pass through intergalactic magnetic fields and charged particles, which rotate the polarization plane of the waves via a well-understood physical process called the "Faraday rotation effect.''
During the past few years, John Ralston of the University of Kansas and I have studied data published by several independent research groups on the polarization of radio waves emitted by synchrotron galaxies. Surprisingly, we found that a wave's polarization plane undergoes an additional rotation that is very different from Faraday rotation. The amazing thing is that the new rotation depends on the direction the wave moves through space. This is reminiscent of how a birefringent - or electromagnetically anisotropic - crystal changes the polarization of light passing through it in a way that depends on the direction the light travels through the crystal.
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Since the new rotation we find has such a systematic directional dependence, it is implausible that it is generated by cosmic ions and fields via some mechanism similar to the Faraday effect. One may therefore surmise that it is the vacuum itself that flaunts a form of electromagnetic birefringence, or anisotropy - similar to the birefringence exhibited by many crystals.
During the past few years, John Ralston of the University of Kansas and I have studied data published by several independent research groups on the polarization of radio waves emitted by synchrotron galaxies. Surprisingly, we found that a wave's polarization plane undergoes an additional rotation that is very different from Faraday rotation. The amazing thing is that the new rotation depends on the direction the wave moves through space. This is reminiscent of how a birefringent - or electromagnetically anisotropic - crystal changes the polarization of light passing through it in a way that depends on the direction the light travels through the crystal.
>
Since the new rotation we find has such a systematic directional dependence, it is implausible that it is generated by cosmic ions and fields via some mechanism similar to the Faraday effect. One may therefore surmise that it is the vacuum itself that flaunts a form of electromagnetic birefringence, or anisotropy - similar to the birefringence exhibited by many crystals.