Scientists have discovered new evidence that the universe was briefly governed by different physical laws than it is today, producing a violation to which we owe our very existence, reports a new study.
The results open a window into the mysterious epoch of inflation, an ultrashort period when the universe expanded exponentially fractions of a second after the Big Bang.
By studying more than a million galaxies observed in sky surveys, researchers were able to show that the universe more often molded galactic groups in a certain cluster shape, as opposed to its mirror image. This finding violates what’s known as parity symmetry, an idea embedded in our current physical models that the universe is essentially symmetrical and does not prefer any shape over its reversed image.
Scientists have long suspected that a so-called “parity violation” occurred in the early universe, in part because matter—the stuff we’re all made of—somehow became far more abundant than antimatter, matter’s oppositely charged counterpart. Our current physical laws suggest that matter and antimatter should have canceled each other out after the Big Bang, but clearly that didn’t happen because, well, we exist, and we’re made of matter, and so is a lot of other stuff, like stars, planets, and galaxies. Antimatter, by comparison, is very rare in the universe today, an unexplained outcome that is considered one of the biggest mysteries in science.
Now, researchers led by Jiamin Hou, a postdoctoral fellow and cosmologist at the University of Florida, have used a supercomputer to analyze an immense dataset that of galaxies organized into trillions of different “quadruplets,” or groups of four galaxies in close proximity that take on a tetrahedral shape.
The results revealed a clear preference for one tetrahedron over its mirror image, offering the first evidence that parity violation in the epoch of inflation influenced the clustering of galaxies later in cosmic history. The new discovery “opens a new avenue for probing new forces during the epoch of inflation with 3D large-scale structure,” according to a study published on Monday in the Monthly Notices of the Royal Astronomical Society.
“What is the beginning of the universe? What are the rules under which it evolves? Why is there something rather than nothing?” said Zachary Slepian, a UF astronomy professor and co-author of the study, in a statement. “This work addresses those big questions.”
The discovery of the weird clustering in galactic quadruplets is a signal that the laws of the universe may have changed in some way during the epoch of inflation. This type of event cannot be explained by the Standard Model of cosmology, a well-corroborated framework that explains a lot of phenomena in our universe. Though the Standard Model is robust, there are many potential challenges to it, including curious evidence that the laws of physics may not apply everywhere in the universe even to this day.
Previous studies have also uncovered hints of parity violations in the early universe, but much of this research examines interactions on tiny subatomic scales, whereas Hou’s team examined the effect on huge cosmic scales. The researchers detailed their novel approach in another new study, which was published this week in Physical Review Letters.
“The detection of a parity-violating signal in [Large Scale Structure of the universe] would illuminate early Universe physics and perhaps even reveal physical processes beyond the Standard Model,” the team said in that study.
While Hou and her colleagues have uncovered strong evidence for parity violation, there are still uncertainties in the measurements that will need to be cross-checked in the coming years. Fortunately, a number of next-generation astronomical surveys are in the works, including the Vera Rubin Observatory in Chile and the European Space Agency’s Euclid telescope, which is due for launch in July. These projects will provide extremely high-quality spectrographic observations that will be useful for studying parity violations on large scales, among many other topics.
We haven’t yet solved the riddle of why the universe contains something, namely matter, instead of nothing, which is how it should have turned out according to our current understanding of physics. But the weirdly clustered galaxies reported by Hou’s team offer new clues about this strange imbalance that ultimately led to our modern reality complete with stars, planets, and people on planets who are trying to figure all of this out.