A neglected particle from the dawn of time could explain why everything in the universe exists

A hypothetical, right-handed neutrino from the dawn of time might have held the key to why the universe exists, according to a new study published in the journal Physical Review Letters. This elusive particle, which is believed to have been far more massive than any other during the early universe, could have driven key particle interactions and even reshaped the expansion dynamics of the cosmos.

Neutrinos, notoriously slippery particles that rarely interact with matter, come in three flavors and possess a subtle quantum property that only holds true if they have mass. Current theory suggests that neutrinos are massless, but the proposed right-handed neutrino could explain the mass of the other neutrinos, as well as their ability to switch between flavors.

The study, led by Rishav Roshan of the University of Southampton and Sudipta Show of the Indian Institute of Technology Kanpur, examined the role of the neglected right-handed neutrino in the early universe. They found that if this massive particle had dominated during the first moments after the Big Bang, it could have significantly altered the expansion dynamics of the cosmos, leading to a period of matter domination.

This matter-dominated phase would have delayed key particle interactions, allowing the conditions necessary for the formation of matter over antimatter to take hold. As a result, the study suggests that a right-handed neutrino with a mass of about 100 billion times that of a proton could have produced the observed matter-antimatter imbalance within the universe.

While the heavy right-handed neutrino is far too massive to be created in a particle accelerator, the researchers' findings offer an indirect means of testing the theory. By studying the potential impact of this neglected particle on the early universe's expansion and the formation of matter, scientists may one day be able to confirm or refute the existence of this potential cosmic game-changer.