William Thomson (Lord Kelvin)
Japanese physicists resurrect a 19th century idea that could explain everything. “Cosmic nodes” were the “grandparents” of all matter in the Universe, and neutrinos were their “parents”.
An old hypothesis by the British physicist Lord Kelvin, long considered obsolete, it may ultimately hide the key to one of the greatest mysteries in cosmology: why the Universe is made of matter and not antimatter.
In 1867, Kelvin suggested that atoms could be tiny knots intertwined in the cosmic “ether.” The idea was eventually discarded with the discovery of the true structure of atoms, but more than 150 years later Japanese researchers gave it new life — and now believe that similar “cosmic knots” may even have played a decisive role in the first moments of the cosmos.
The study, in the journal Physical Review Letters and led by Muneto Nitta and Minoru Eto, from the International Institute for Sustainability with Intertwined Chiral Matter (WPI-SKCM2) at Hiroshima University, in collaboration with Yu Hamada, from the German center Deutsches Elektronen-Synchrotron, shows that these formations can arise naturally in realistic particle physics models and that their collapse may have created the slight imbalance between matter and antimatter that allowed the existence of everything we know — from stars to human beings.
The enigma of missing antimatter
According to the Big Bang model, the Universe should have been born with equal amounts of matter and antimatter, which would annihilate each other until only radiation remained. However, observations show a cosmos almost entirely composed of matter. According to calculations, for every billion matter–antimatter pairs formed at the beginning of time, only a speck of matter survived.
The explanation for this difference — a phenomenon known as baryogenese — still escapes the Standard Model of particle physics, whose ability to predict this imbalance is very limited. Solving the problem has been one of the top priorities in theoretical physics for decades, as .
Two symmetries and a knot
The Japanese team believes they have found a crucial clue by combining two known extensions of the Standard Model: the Baryon Number minus Lepton Number (B–L) symmetry and the Peccei–Quinn (PQ) symmetry. The first explains the origin of the mass of ghostly particles called neutrinos; the second solves the so-called “strong CP problem” — the absence of a measurable electric dipole moment in the neutron — and introduces the axiona promising dark matter particle candidate.
By studying these two symmetries simultaneously (something no one had done before) researchers discovered that the early Universe may have spontaneously generated intertwined structuressimilar to us, which accumulated energy and had magnetic and superfluid properties. These knots were stable, topologically protected formations that emerged when fundamental symmetries “broke” during cosmic cooling after the Big Bang.
The age of us
While the radiation lost energy with the expansion of space, these knots behaved like matter, dissipating much more slowly. For a brief period, they dominated the total energy of the Universebefore they begin to fall apart through a quantum process known as tunneling, in which particles cross seemingly insurmountable energy barriers.
When they collapsed, the knots released heavy particles — namely straight neutrinos, predicted by B–L symmetry — which, when they decayed, they slightly favored the production of matter to the detriment of antimatter. This difference was enough to generate all the matter that today makes up the cosmos.
The scientists’ calculations showed that, when assuming a mass of around 10¹² giga-electron volt (GeV) for heavy neutrinos and considering that the nodes channeled most of their energy to generate these particles, the model naturally reproduces the imbalance between matter and antimatter observed in the Universe. The collapse of the knots would have reheated the cosmos to around 100 GeV — precisely the threshold temperature at which reactions that convert an excess of neutrinos into matter stop occurring.
This process would also have modified the gravitational wave background of the Universe, tilting it towards higher frequencies. This “signature” could be detected in the future by the large observatories that we have built and plan to build here.
Although the work remains theoretical, the authors believe that their model is robust, as the topological stability of the nodes does not depend on the specific details of the theory.
This time, 150 years later, we are not the constituents of atoms, but perhaps their cosmic predecessors. Or “grandparents”, if you want to call them that.
If confirmed, the theory could finally unite long-dispersed pieces, from the origin of neutrino mass to the nature of dark matter.
