Oct 29, 2026 09:55 PM
(This post was last modified: Oct 30, 2026 04:26 AM by C C.)
https://www.livescience.com/physics-math...rse-exists
EXCERPTS: A neglected "ghost particle" may have dominated the universe right after the Big Bang — changing how the cosmos expanded in its first moments and reshaping the conditions under which matter won out over antimatter, a new study suggests. In other words, it may explain why anything exists at all.
The particle, a hypothetical "right-handed" neutrino, briefly could have held more energy than everything else in the infant universe combined, which would have sped up cosmic expansion and delayed key particle interactions, the study proposes. The research was published in the journal Physical Review Letters.
[...] In the new study, Roshan and Sudipta Show, a physicist at the Indian Institute of Technology Kanpur, examined what this neglected particle — which, in the team's main example, was about 100 trillion times as heavy as a proton — would have done after the Big Bang.
At first, the particle would have zipped around at nearly light speed, so its energy would have faded like that of light, which would have both spread out and stretched to weaker wavelengths as space expanded. But as the cosmos cooled, the particle would have slowed down and most of its energy would have become locked in its mass, which would have been only spread out. Its share of the cosmic energy therefore would have grown until it dominated, and the long-lived particle would have stayed in charge until it decayed into other particles, according to the team's computations.
The study reveals that the neglected right-handed neutrino "significantly impacts the early universe's expansion dynamics, driving a period of early matter domination," Roshan said. This change "affects various Standard Model interactions" that could help to explain the matter-antimatter asymmetry, Roshan added.
Each interaction would have switched on only once it outpaced the expansion of space. Because a universe dominated by the heavy neutrino would have expanded faster, the interactions would have had to wait until it cooled further.
These interactions would have let the early universe distinguish lepton flavors, which would have affected how the matter surplus formed. Thanks to the delay, the team found, a lighter right-handed neutrino about 100 billion times as heavy as a proton could have produced the observed amount of matter before the flavors could be told apart — even after the heavy neutrino's decay diluted part of it... (MORE - missing details)
EXCERPTS: A neglected "ghost particle" may have dominated the universe right after the Big Bang — changing how the cosmos expanded in its first moments and reshaping the conditions under which matter won out over antimatter, a new study suggests. In other words, it may explain why anything exists at all.
The particle, a hypothetical "right-handed" neutrino, briefly could have held more energy than everything else in the infant universe combined, which would have sped up cosmic expansion and delayed key particle interactions, the study proposes. The research was published in the journal Physical Review Letters.
[...] In the new study, Roshan and Sudipta Show, a physicist at the Indian Institute of Technology Kanpur, examined what this neglected particle — which, in the team's main example, was about 100 trillion times as heavy as a proton — would have done after the Big Bang.
At first, the particle would have zipped around at nearly light speed, so its energy would have faded like that of light, which would have both spread out and stretched to weaker wavelengths as space expanded. But as the cosmos cooled, the particle would have slowed down and most of its energy would have become locked in its mass, which would have been only spread out. Its share of the cosmic energy therefore would have grown until it dominated, and the long-lived particle would have stayed in charge until it decayed into other particles, according to the team's computations.
The study reveals that the neglected right-handed neutrino "significantly impacts the early universe's expansion dynamics, driving a period of early matter domination," Roshan said. This change "affects various Standard Model interactions" that could help to explain the matter-antimatter asymmetry, Roshan added.
Each interaction would have switched on only once it outpaced the expansion of space. Because a universe dominated by the heavy neutrino would have expanded faster, the interactions would have had to wait until it cooled further.
These interactions would have let the early universe distinguish lepton flavors, which would have affected how the matter surplus formed. Thanks to the delay, the team found, a lighter right-handed neutrino about 100 billion times as heavy as a proton could have produced the observed amount of matter before the flavors could be told apart — even after the heavy neutrino's decay diluted part of it... (MORE - missing details)
