Scientists believe they have found a solution to one of the oldest problems in the universe

Scientists believe they have found a solution to one of the oldest problems in the universe

It’s one of the oldest problems in the universe: since matter and antimatter annihilate each other on contact, and both forms of matter existed at the time of the big bang, why is there a universe made mostly of matter in place of nothing? Where did all the antimatter go?

“The fact that our present-day universe is dominated by matter remains one of the most puzzling and long-standing mysteries of modern physics,” Yanou Cui, a professor of physics and astronomy at the University of California, said in a shared statement this week. “A subtle imbalance or asymmetry between matter and antimatter in the early universe is required to achieve the current dominance of matter, but it cannot be realized within the known framework of fundamental physics.”

There are theories that could answer this question, but they are extremely difficult to test with laboratory experiments. Now, in a new article published Thursday in the journal Physical review lettersthe Dr. Cui and his co-author, Zhong-Zhi Xianyu, an assistant professor of physics at Tsinghua University in China, say they may have found a work around using the afterglow of the big bang itself to run the experiment.

The theory that Drs Cui and Zhong-Zh wanted to explore is known as leptogenesis, a process involving the decay of particles that could have led to the asymmetry between matter and antimatter in the early universe. An asymmetry in certain types of elementary particles in the earliest moments of the cosmos, that is, could have grown over time and through subsequent particle interactions to the asymmetry between matter and antimatter that made the universe as we know it – and life -. possible

“Leptogenesis is one of the most compelling mechanisms that generate the matter-antimatter asymmetry,” Dr. Cui said in a statement. “It involves a new fundamental particle, the right neutrino.”

But, Dr. Cui added, generating a right neutrino would require much more energy than can be generated in particle colliders on Earth.

“Proving for leptogenesis is almost impossible because the mass of the right neutrino is typically many orders of magnitude beyond the reach of the highest energy collider ever built, the Large Hadron Collider,” he said .

The idea from Dr. Cui and his co-authors was that scientists may not need to build a more powerful particle collider, because the same conditions they would like to create in this experiment already existed in parts of the early universe. The inflationary period, an era of exponential expansion of time and space itself that lasted only fractions of a second after the big bang,…

“Cosmic inflation provided a highly energetic environment, which allowed the production of new heavy particles as well as their interactions,” said Dr. Cui. “The inflationary universe behaved like a cosmological collider, except that the energy was up to 10 billion times greater than any man-made collider.”

Furthermore, the results of these natural cosmological collider experiments can be preserved today in the distribution of galaxies, as well as in the cosmic microwave background, the afterglow of the big bang from which astrophysicists have derived large part of their current understanding of the evolution of the cosmos. .

“Specifically, we show that the essential conditions for asymmetry generation, including the interactions and masses of the right-handed neutrino, which is the key player here, can leave distinctive fingerprints on the statistics of the spatial distribution of galaxies or the cosmic microwave background and can be accurately measured,” said Dr. Cui, although making such measurements, he added, remains to be done. “Astrophysical observations planned in the coming years may detect these signals and unravel the cosmic origin of matter.”

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