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

In a groundbreaking study, a team of physicists from Hiroshima University has revived a concept proposed by Lord Kelvin over 150 years ago. Their research suggests that “cosmic knots” could help explain why the universe is predominantly made of matter rather than antimatter. This age-old theory has been reinterpreted to address a significant enigma in cosmology: the mystery of matter-antimatter asymmetry.

The initial idea, introduced in 1867 by Lord Kelvin, envisioned atoms as complex knots within the hypothetical medium known as aether. Although this notion was soon invalidated, its potential implications have persisted. The current study proposes that these knots, which are topologically stable tangles in spacetime, could have formed during the universe’s early moments. These cosmic knots may have collapsed in a manner that favored the creation of matter over antimatter.

Understanding Matter-Antimatter Asymmetry

According to the prevailing theories of the Big Bang, an equal amount of matter and antimatter should have been produced. Anticipated interactions would have led to their annihilation, leaving only radiation. Observations, however, reveal a stark imbalance: for every billion matter-antimatter pairs, only one matter particle remains. This imbalance is crucial, as the visible structures of the universe, from atoms to galaxies, are composed predominantly of matter.

Despite its successes, the Standard Model of particle physics has yet to account for this discrepancy. The question of why the universe is made of matter instead of antimatter is fundamental to understanding our existence. Professor Muneto Nitta, the study’s corresponding author, emphasized that this inquiry is pivotal for comprehending the formation of stars, galaxies, and ultimately, life itself.

Nitta and his team believe they have identified a potential mechanism behind this imbalance, known as baryogenesis. By integrating a gauged Baryon Number Minus Lepton Number (B-L) symmetry with the Peccei–Quinn (PQ) symmetry, they demonstrated that the formation of cosmic knots in the universe’s infancy could account for the observed surplus of matter.

Cosmic Knots and Their Implications

The PQ symmetry addresses the strong CP problem and suggests the existence of axions, which are considered a leading candidate for dark matter. Meanwhile, the B-L symmetry explains the behavior of neutrinos, often referred to as “ghost particles,” which can traverse matter with minimal interaction.

As the early universe cooled, phase transitions may have led to the formation of cosmic strings—hypothetical fissures in spacetime. The researchers propose that a combination of flux-carrying B-L strings and superfluid-like PQ vortices contributed to the emergence of stable knot solitons. Nitta remarked, “Nobody had studied these two symmetries at the same time. Putting them together revealed a stable knot.”

Eventually, these knots decayed through a process known as quantum tunneling, which produced heavy right-handed neutrinos. This phenomenon created a scenario in which more matter than antimatter could exist. The researchers’ calculations indicate that the masses of the heavy neutrinos and the energy released from the collapse of the knots led to a reheating of the universe to approximately 100 GeV. This temperature is critical for sustaining the formation of matter.

Moreover, the team theorizes that this process may have altered the universe’s “gravitational wave chorus,” shifting it toward higher frequencies. They suggest that future gravitational wave observatories, such as the Laser Interferometer Space Antenna (LISA) in Europe, Cosmic Explorer in the United States, and the Deci-hertz Interferometer Gravitational-wave Observatory (DECIGO) in Japan, could eventually detect these subtle changes.

This research not only revisits a long-standing hypothesis but also opens new avenues for understanding the fundamental nature of our universe. As scientific exploration continues, these cosmic knots may ultimately provide answers to some of the most profound questions regarding the existence and composition of the universe.