Asymmetry detected in the distribution of galaxies

Asymmetry detected in the distribution of galaxies

Katie McCormick writes:

Physicists believe they have detected a striking asymmetry in the arrangements of galaxies in the sky. If confirmed, the finding would point to features of the unknown fundamental laws that operated during the Big Bang.

“If this result is real, someone’s going to get a Nobel Prize,” said Marc Kamionkowski, a physicist at Johns Hopkins University who was not involved in the analysis.

As if playing a cosmic game of Connect the Dots, the researchers drew lines between sets of four galaxies, constructing four-cornered shapes called tetrahedra. When they had built every possible tetrahedron from a catalog of 1 million galaxies, they found that tetrahedra oriented one way outnumber their mirror images.

A hint of the imbalance between tetrahedra and their mirror images was first reported by Oliver Philcox, an astrophysicist at Columbia University in New York, in a paper published in Physical Review D in September. In an independent analysis conducted simultaneously that’s now undergoing peer review, Jiamin Hou and Zachary Slepian of the University of Florida and Robert Cahn of Lawrence Berkeley National Laboratory detected the asymmetry with a level of statistical certainty that physicists usually consider definitive.

But with such a blockbuster finding — and one that’s still under review — experts say caution is warranted.

“There’s no obvious reason that they’ve made a mistake,” said Shaun Hotchkiss, a cosmologist at the University of Auckland. “That doesn’t mean that there isn’t a mistake.”

The putative imbalance violates a symmetry called “parity,” an equivalence of left and right. If the observation withstands scrutiny, physicists think it must reflect an unknown, parity-violating ingredient in the primordial process that sowed the seeds of all the structure that developed in our universe. [Continue reading…]

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