Ghost particle to solve the mystery of the Universe
A small particle, the neutrino, might be able to destroy itself, revealing why there is dark matter in the universe.
When the universe was created in the Big Bang 13.8 billion years ago, equal quantities of matter and antimatter were created. Matter is what we consist of and live in. Antimatter is made of particles with opposite qualities. A proton is matched by an antiproton with the opposite charge, and electrons are matched by positrons.
When matter and antimatter meet, they are annihilated, and that was how most matter and antimatter disappeared shortly after the Big Bang. All of it ought to be gone, and one of the major mysteries of physics is why some matter was left to form stars, planets, and galaxies.
According to some physicists, the secret is a small, ghost-like particle known as a neutrino, that may be its own antiparticle. This could explain that there was an imbalance between matter and antimatter in the young universe. Physicists have tried to answer the question in experiments, and they are upgrading their equipment with an experiment in the GERDA detector in the mountains of Gran Sasso, Italy, where they will study the radioactive decay of a special version of the germanium element. During the decay, a neutron in the atomic nucleus is converted into a proton, as an electron and an antineutrino are emitted. In rare cases, two instances of decay happen at the same time, producing two antineutrinos. If the two particles immediately destroy each other, so physicists cannot measure them, antineutrinos and neutrinos must be the same – and we will know where all matter in the universe comes from.