Japanese Physicists Revive 150-Year-Old Knot Theory to Explain Universe’s Matter

In a remarkable fusion of 19th-century theory and modern physics, a team of Japanese physicists has revived a hypothesis proposed by Lord Kelvin in 1867 to address a fundamental question in cosmology: why does the universe contain so much matter but so little antimatter? Their research suggests that “cosmic knots,” which are stable structures in spacetime, may have formed in the early universe, leading to an imbalance favoring matter. This study, led by Muneto Nitta from Hiroshima University, presents a new perspective on a long-standing mystery.

The research team proposes that during the universe’s infancy, it underwent phase transitions that created these cosmic knots, which subsequently collapsed in a manner that favored the production of matter over antimatter. This phenomenon could help explain why, instead of an equal amount of both, the universe is predominantly composed of matter.

The Mystery of Matter-Antimatter Asymmetry

Current theoretical models, including the Big Bang theory, suggest that an equal amount of matter and antimatter should have been generated. The expectation is that these particles would annihilate each other, leaving behind only radiation. However, current observations reveal a striking asymmetry: for every billion matter-antimatter pairs, only one matter particle remains. This imbalance is critical for the existence of visible structures, such as stars and galaxies.

Despite the success of the Standard Model of particle physics in describing matter’s fundamental components, it fails to account for this discrepancy. Nitta emphasizes the significance of this research, stating, “This study addresses one of the most fundamental mysteries in physics: why our Universe is made of matter and not antimatter. This question is important because it touches directly on why stars, galaxies, and we ourselves exist at all.”

The researchers are exploring the theoretical framework of baryogenesis, which seeks to explain how this matter-antimatter imbalance occurred. By combining the Baryon Number Minus Lepton Number (B-L) symmetry with the Peccei–Quinn (PQ) symmetry, they propose a scenario in which cosmic knots could form and lead to a surplus of matter.

Understanding Cosmic Knots and Their Implications

The study indicates that as the universe cooled, phase transitions produced thread-like defects known as cosmic strings. These hypothetical structures are believed to exist in spacetime and may have important implications for the formation of stable knot solitons. The researchers discovered that the combination of B-L strings and superfluid-like PQ vortices allowed for these stable knots to emerge.

Nitta notes, “Nobody had studied these two symmetries at the same time. Putting them together revealed a stable knot.” Eventually, these knots are theorized to decay through quantum tunneling, resulting in the production of heavy right-handed neutrinos. This process is believed to have generated more matter than antimatter, leading to the conditions necessary for the universe as we know it.

The team’s calculations suggest that the decay of these knots resulted in a reheat of the universe to approximately 100 GeV, which is critical for the formation of lasting matter. This finding could dramatically shift our understanding of the universe’s evolution.

Additionally, the research posits that this process may have altered the universe’s “gravitational wave chorus,” potentially shifting it toward higher frequencies. The authors believe that future observatories, such as the Laser Interferometer Space Antenna (LISA) in Europe, the Cosmic Explorer in the United States, and the Deci-hertz Interferometer Gravitational-wave Observatory (DECIGO) in Japan, could detect this subtle shift in gravitational waves.

Through this innovative approach, the researchers not only breathe new life into a historical concept but also pave the way for future explorations that may one day unravel the mysteries of our universe’s origins. As the scientific community continues to grapple with these profound questions, Nitta and his team’s work represents a significant step towards understanding the fundamental nature of reality.