Right now there are four major experiments being conducted around the world, hunting for signs of barely-detectable particles undergoing rare changes. In an article for Science Alert, Mike Mcrae explains why matter shouldn’t exist based on our current understanding of physics.
As subatomic particles cooled out of the radiation following the first moments of Universe, they took one of two forms—matter and antimatter. Therein lies the paradox, however, because these mirror-opposite objects also cancel out in a flash of energy when they meet again. So, if both types of particles are created next to one another in equal amounts, the math says we should have nothing left over. However, most visible objects are made from just one kind of particle—matter.
Neutrinos (a type of neutrally charged particle) may provide answers to this paradox. Neutrinos are a million times lighter than an electron, meaning they barely interact with other particles. Properties of these ‘ghost particles’ may mean that neutrinos are matter and anti-matter in one. Exploring neutrinos may be the pathway to explaining why our universe didn’t immediately cancel itself out.
Experiments are taking place to explore this mystery. The Cryogenic Underground Observatory for Rare Events (CUORE) at Gran Sasso Laboratory in Italy is based on just a flash in one of 1,000 crystals of tellurium dioxide to advertise the moment of neutrinoless double beta decay. They expect to see only five decays in the next five years. CUORE member, Lindley Winslow told Jennifer Chu at MIT News that it’s a very rare process. “If observed, it would be the slowest thing that has ever been measured,” she said. A second experiment at Gran Sasso is using isotope germanium-76 instead. They have less material to catch the decay, but the whole set-up is proving to be extremely sensitive, reducing the risk of missing the event if it happens.
In the U.S. at the Sanford Underground Research Facility, collaborators are working on an experiment called the MAJORANA Demonstrator. All of these experiments are looking for the conservation of a particular quantum number as pairs of neutrons decay within certain isotopes. To-date, the results from these experiments have narrowed the field of places to search for neutrinos.