IS THE UNIVERSE SPINNING? A NEW STUDY SUGGESTS IT IS.

What with the coronavirus pandemic and the associated economic meltdown, the Trump presidency and rioting across the US, it's no surprise if you feel your head spinning. To add to that, research presented today at the 236th meeting of the American Astronomical Society suggests that the whole universe may be spinning. If further studies bear this out, the finding will challenge some of the fundamental assumptions of modern cosmology.

Distribution of galactic spins across the sky

Credit: Lior Shamir, KSU

Lior Shamir, a computational astronomer at Kansas State University, has spent ten years studying galactic spin. Early on, he began to suspect that galaxies spinning clockwise versus counter-clockwise were not scattered randomly throughout the universe, as standard cosmological models assumed. It took today's advanced telescopic surveys and massive computational capacity to put his radical idea to the test.

Shamir analyzed 200,000 galaxies imaged by the Sloan Digital Sky Survey (SDSS) and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). He used a deterministic and symmetrical computer vision system to identify each galaxy's direction of rotation--that is, there was nothing in the way the images were analyzed that could bias the system towards detecting a clockwise or counter-clockwise rotation.

What Shamir found contradicts the cosmological principle, a fundamental assumption of modern cosmology, which assumes that at large scales the universe is essentially the same--isotropic--no matter where we look.

The universe is not isotropic, Shamir found. First, there's a roughly two percent difference between the number of galaxies spinning clockwise and counter-clockwise (with more spinning counter-clockwise as viewed from Earth). Secondly, this difference was more pronounced when the universe was younger. And thirdly and most strikingly, the ratio of clockwise to counter-clockwise spinning galaxies varies in a systematic way across the sky. 

With 200,000 data points, the differences Shamir found, although small, are statistically highly significant. There's just one chance in four billion that they could have appeared by chance. 

Following extensive data analysis, Shamir showed that the model that best matches the observed distribution of spins is a universe with two axes, a so-called quadrupole distribution. "If the universe has an axis," Shamir says, "it is not a simple single axis like a merry-go-round. It is a complex alignment of multiple axes."

One explanation of these new findings is that the universe was born spinning, and that primordial spin led to more galaxies rotating one way than the other. 

"Given the evidence, a spinning universe is one of the interpretations that we should look into and consider very seriously," Shamir says. "But I cannot make a definite statement at this point that the universe is indeed spinning or was spinning. There can be other interpretations."

So we can't yet be sure that the universe was born with a spin. But Shamir's new evidence that galactic spins favor one direction and are are not distributed symmetrically in space and time should provoke a deep re-think of the assumptions cosmologists have made for decades. 

"The main thing is that we can see clear, defined patterns at a scale far larger than any astrophysical structure," Shamir explains. "The idea that the universe has a defined structure is foreign to almost all 'mainstream' cosmological models. Explaining it will reinforce new models that will substantially shift from the models that we have today."

In other words, our understanding of the universe is far from complete. I can't wait for the next chapter.

REA

DARK MATTER FILAMENTS LINK GALAXIES INTO A COSMIC WEB

Scientists still don't know what dark matter is, although there appears to be five times more of it than of normal, visible matter, and cosmologists believe that it has played a crucial role in the evolution of the universe.

Since it doesn't interact with light or other electromagnetic radiation, and barely if at all with normal matter except through gravity, it's not surprising that it's proven excruciatingly hard to detect. A long series of increasingly sensitive experiments have narrowed the range of possible targets, but so far have failed to find actual dark matter particles.

Now, researchers at the University of Waterloo, in Ontario, Canada, have confirmed one of the key predictions of how dark matter should act by imaging for the first time strands or bridges of dark matter linking neighboring galaxies.

Dark matter filaments bridge the space between galaxies in this false colour map. The locations of bright galaxies are shown by the white regions and the presence of a dark matter filament bridging the galaxies is shown in red. Credit: S. Epps & M. Hudson / University of Waterloo

Astronomer Michael Hudson and graduate student Seth Epps detected the dark matter bridges through the gravitational lensing effect they had on the light coming from even-more-distant galaxies. The image above combines the observations of 23,000 galaxy pairs, which allowed the researchers to detect the dark matter filaments with a high degree of statistical certainty.

“For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together,” said Hudson. “This image moves us beyond predictions to something we can see and measure.”

Their work proves the prediction that rather than isolated "island universes," galaxies and even larger galaxy clusters are like beads of condensation on an invisible cosmic web of dark matter.

Beads of water on a spider's web

https://goo.gl/images/RJO6Xe

You can find the original paper here.

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