Are The Galaxies In Our Universe More Right-Handed… Or Left-Handed?

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It’s called mirror symmetry and it has everything to do with a recent study done by physics professor Michael Longo and a team of five undergraduates from the University of Michigan. Their work encompasses the rotation direction of tens of thousands of spiral galaxies cataloged by the Sloan Digital Sky Survey. What they’re looking for is the shape of the Big Bang… and what they found is much more elaborate than they thought.

By utilizing SDSS images, the team began looking for mirror symmetry and evidence the early universe spun on an axis. “The mirror image of a counter-clockwise rotating galaxy would have clockwise rotation. More of one type than the other would be evidence for a breakdown of symmetry, or, in physics speak, a parity violation on cosmic scales.” Longo said. However, there seems to be a certain “spin preference” when it comes to spiral galaxies toward the north pole of the Milky Way. Here they found an abundance of left-handed, or counter-clockwise rotating, spirals – an effect which extended beyond an additional 600 million light years.

“The excess is small, about 7 percent, but the chance that it could be a cosmic accident is something like one in a million,” Longo said. “These results are extremely important because they appear to contradict the almost universally accepted notion that on sufficiently large scales the universe is isotropic, with no special direction.”

On the other hand, be it left or right, Galaxy Zoo has done some very interesting research into mirror symmetry as well. In conjunction with the Sloan Digital Sky Survey, the team also involved the public for their input – a total of 36 million classifications for 893,212 galaxies from 85,276 users. The GZ study is absolutely fascinating and took every variable into account.

“We wish to establish the large scale statistical properties of the galaxy spins. Although there is some level of uncertainty in the overall number counts, it is still possible to look for a dipole, for example, in the spin distributions.” says Kate Land, et al. “Curiously, the dipoles from these two analyses are in completely opposite directions. The samples cover different amounts and parts of the sky, with SDSS mainly in the Northern hemisphere and the sample of Sugai & Iye (1995) predominantly in the Southern hemisphere. In both cases the dipoles tend to point away from the majority of the data but neither analysis fits for a monopole or takes account of their partial sky coverage in assessing the dipole. With incomplete sky coverage the spherical harmonic decomposition is no longer orthogonal and for a sample covering less than half of the sky it is hard to tell the difference between a monopole (an excess of one type over the other) and a dipole (an asymmetry in the distribution).”

So what’s the end result? Well, chances are good that our universe was born spinning… but like any family, there isn’t much evidence one way or another that says most members have to be right – or left – handed. It’s more about how we, as humans, perceive them…

Original Story Source: University of Michigan New Service. For further information, read Galaxy Zoo: The large-scale spin statistics of spiral galaxies in the Sloan Digital Sky Survey.