Asymmetry Detected in the Distribution of Galaxies

Physicists think they have found a striking discrepancy in the arrangement of the galaxies. The features of the unknown fundamental laws would be pointed out if the finding is proven correct.

A physicist who was not involved in the analysis said someone is going to get a prize if the result is true.

As if playing a game of connect the dots, the researchers drew lines between sets of four galaxies and constructed four-cornered shapes. From a catalog of 1 million galaxies, they found that there was one way to outnumber their mirror images.

A paper by Oliver Philcox, an astronomer at Columbia University in New York, was published in Physical Review D in September of this year. Physicists usually consider definitive the level of statistical certainty found in the analysis conducted by the University of Florida and Lawrence Berkeley National Laboratory.

There is a blockbuster finding and one that is still being reviewed.

There's no obvious reason that they've made a mistake It doesn't mean there isn't a mistake.

The symmetry of left and right is violated by the discrepancy. Physicists think the observation reflects an unknown ingredient in the primordial process that sowed the seeds of the structure that developed in our universe.

Kamionkowski said it was an amazing result. Is it true? I'm not going to celebrate right away.

Left-Handed Universe

The symmetry of physics used to be a cherished one. The Chinese American physicist Chien-Shiung Wu discovered in 1957 that our universe has a slight handedness to it, because subatomic particles involved in the weak nuclear force, which causes nuclear decay, are always magnetically oriented in the opposite direction. Right-handed screws and mirror-image particles don't feel the weak force

It was shocking. The physicist wrote a letter to Wolfgang Pauli about the death of parity.

The left-handedness of the weak force can have effects that can't be seen on the scales of the universe. Physicists have sought other ways in which the universe is different from the mirror image.

When the universe was in its infancy, a primordial parity violation could have changed the structure of the universe.

The inflaton is thought to have existed at the time of the universe's birth. The inflaton field would have caused our universe to grow to 100 trillion times its original size if it existed at the time. All of the quantum fluctuations in the inflaton field were flung out and into the universe. The denser pockets coalesced to create the large structure we see today.

If more than one field was present, what would happen? Right- and left-handed particles could be produced by the inflaton field. If the inflaton treated right-handed particles differently than left-handed ones, it would create particles of one handedness over the other. The early quantum fluctuations would have been imprinted with a preferred handedness, which would have led to an unbalanced arrangement of the galaxies.

There is a chance that the additional field could be the gravity field. In this scenario, there would be an interaction between the inflaton particles and the quantum units of gravity. The handedness of the early universe would have been created by this interaction.

One of the biggest mysteries in astronomy is why our universe has more matter than antimatter. He thought that the interaction could have created left-handed matter over right-handed antimatter.

Alexander's idea was not well known for a long time. He was surprised to hear about the new findings.

Tetrahedra in the Sky

Cahn thought the possibility of finding a solution to the matter-antimatter puzzle with parity violation was provocative. He looked for parity violation in a catalog of galaxies. He thought it would be worth a check.

To find out if the distribution respects or violates parity, he and his colleagues needed to study the arrangement of four different galaxies. The simplest three-dimensional shape is the tetrahedron, and only 3D objects can violate parity. Consider your hands if you want to understand this. There is no way to make a left hand look like a right hand. If you flip your left hand over, you'll see that the palms of both hands are different. If you trace a left hand on a sheet of paper and cut out a 2D image, you can make it look like a right hand. There is a cutout and a mirror image.

The number of left- and right-handed people in the sky was compared by the two scientists. The first thing they did was look at the distances to three other stars. The tetrahedron was called right-handed if the distances increased in the clockwise direction. It was left-handed if the distances went clockwise.

To find out if the universe as a whole has a preferred handedness, they had to repeat the analysis for all the tetrahedra they had built. An intractable list to handle one at a time is one of the factors that makes it difficult to handle such a large amount of them. The researchers were able to group all the other galaxies according to their distances from each other because of a factor trick developed in earlier work. They could combine sets of three layers if they expressed the relative positions of the galaxies in each layer.

The researchers compared the results to their expectations. Hou was the one who led this step, analyzing fake catalogs of galaxies that had been created by simulating the evolution of the universe. Hou and her colleagues were able to figure out how the tally of left- and right-handed tetrahedra differed in a mirror-symmetric world.

The team found a seven-sigma level of parity violation in the real data, meaning that the difference between left and right-handed tetrahedra was seven times as large as could be expected from random chance.

Kamionkowski said that it was amazing that they were able to do that. It is a very complex analysis.

Philcox used similar methods, but he made some different choices, like grouping the galaxies into fewer layers than Hou and colleagues, and omitting some problematic tetrahedra from the analysis. Researchers are looking at the differences between their analyses. All parties are cautious even after trying to understand the data.

Corroborating Evidence

New physics could possibly answer long-standing questions about the universe. The work has yet to begin.

Physicists must verify the observation. There are new surveys on which to do the analysis. Fourteen million galaxies have been recorded so far and the survey will contain more than 30 million when it is done. Cahn said that it will give them an opportunity to look at this in a more detailed way.

If the signal is real, it could show up in other data. Our earliest snapshot of spatial variations in the universe can be found in the oldest light in the sky, the Cosmic Microwave Background. The light should have the same correlation as the galaxies that formed later. It should be possible to find a signal in the light, according to physicists.

The pattern of gravitational waves that may have been created during inflation will be a good place to look. In a parity-preserving world, the ripples in the space-time fabric could be either right- or left-handed. If physicists can measure this background and find that one handedness is favored, this would be an unambiguous, independent check of parity in the early universe.

The models of inflation that could have produced the signal will be studied by theorists. With Giovanni Cabass, a theoretical physicist at the Institute for Advanced Study in New Jersey, Philcox recently used his measurement to test a bunch of parity-violating models of inflation. They don't know which model is correct.

Alexander is focused on understanding gravity. Alexander has begun to work out subtle details about how the early universe would affect the distribution of today's galaxies.

He said that he was the only one pushing it. People are taking an interest.

This editorially independent magazine is supported by the Simons Foundation. Oliver Philcox gets funding from the foundation.

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