Why do we exist? Scientists say a long-overlooked particle may hold a clue

Philosophers and physicists have long asked why there is something rather than nothing. The question has been called “the fundamental question of metaphysics.” Physics has its own version of it. Current theories say that the Big Bang should have produced matter and its opposite, which is called antimatter. And that the two should have wiped each other out.

But even then, we exist. Now, researchers believe that they may have found an answer to this decades-old question. Here’s what this new study says. 

Matter and antimatter can destroy each other when they meet. And if they were created in balance after the Big Bang, there would be nothing. Yet we are here. As per Dr. Rishav Roshan of the University of Southampton, “The fact that we are here at all proves that an asymmetry between matter and antimatter occurred.”

Neutrinos are known to be one of the lightest particles in the universe. Researchers from the University of Southampton and IIT Kanpur have now examined them in a new study. This particle is mostly overlooked because it’s thought to be too weak to influence other particles. 

Commenting on this, Dr. Rishav Roshan said, “This decoupled heavy neutrino has long been dismissed as an irrelevant background detail in particle physics.” The team found it may have mattered after all.

According to this study, this particle may have stayed long after the Big Bang and become the main source of energy that filled the universe. Roshan explained, “As the cosmos cooled after the Big Bang, the particle lived long enough that it temporarily took over the energy density of the universe and triggered a matter-dominated period.”

The study also notes that this particle may have also affected the temperature at which electrons and other leptons met their antiparticles in the early universe.

Dr. Sudipta Show of IIT Kanpur said this shift can leave “distinct but detectable imprints of changes, for example on primordial gravitational waves.” The paper, published in Physical Review Letters, points to neutrino oscillation measurements and gravitational wave observations as possible clues.

Adding to this, Show noted, “These gravitational wave signatures open up new avenues for us to unravel the evolution of the early universe after the Big Bang.”