Every second, 100 trillion tiny particles called “neutrinos” pass through your skin. Nearly all of these particles can penetrate your skin without interfering. These particles are extremely difficult to detect by physicists due to their shyness.
A Russian experiment was conducted deep below the Caucasus Mountains. Physicists found additional evidence, which was published on June 9, in two papers. They also discovered that some of the current theories of neutrinos are out of date. If the experiment is correct, it could reveal a rare type of neutrino which could fly further under the radar. This could explain why, the dark matter that forms most of the universe, is not visible to us.
“It is probably, in my opinion, one of most important results neutrino physics has seen, at least in recent five years,” stated Ben Jones (a neutrino physicist at Texas at Arlington), who was not involved in this experiment.
The case involving the misbehaving neutrinos
Neutrinos, like other creatures from an extraterrestrial plane, react to their physical surroundings very sparingly. They don’t exhibit electromagnetism due to their zero electric charge. They also do not participate in strong nuclear interactions, which help bind particles together at the heart of atoms.
However, neutrinos can play a role in weak nuclear forces. According to the Standard Model (the theoretical framework that provides the foundation for modern particle Physics), certain radioactivity types are caused by the weaker nuclear force
The majority of neutrinos seen on Earth were created by radioactive reactions in the sun. Scientists use neutrino observatories either under the sea or buried below the planet’s surface to watch these. It is difficult to check if neutrino detectors function properly so physicists calibrate their equipment by placing certain radioactive elements (such as chromium-51) near the planet’s crust.
Researchers began to notice an oddity as neutrino theory gained momentum in the 1990s. They found that there were fewer neutrinos in some experiments when they calibrated the detectors. This was contrary to theoretical particle Physics.
In 1997 at Los Alamos National Labs in New Mexico scientists from Russia and the USA set up a tank that contained gallium. Gallium is a metal that melts on a hot summer day. The elements’ atoms absorb the neutrinos as they strike gallium. This transformed gallium to germanium, which is a kind of reversed radioactive decay. To determine the number of neutrinos that had passed through the tank’s germanium, physicists measured it.
Los Alamos found too many galliums and too few neutrinos in their system when they tested it using chromium-51. This defect was called the “gallium anomaly”.
Experts have been studying the gallium anomaly since then and have come up with a tentative explanation. Particle physicists have discovered that neutrinos can be classified into three flavors: electron neutrinos (muon neutrinos), and tau neutrinos (tau neutrinos), each of which plays a different role in the dance of the quantum world. It is possible for neutrinos to switch between flavors under certain conditions. These shifts are known as “neutrino oscillations”.
This led to an interesting possibility: neutrinos could have been missing from the gallium anomaly due to their jumping into another hidden flavor that is even less reactive to physical reality. The category was named by physicists: sterile neutrinos.
Although the sterile neutrino story was a concept, it gained support. Around the same period, physicists from Los Alamos as well as the Fermilab in suburb Chicago began to observe neutrino oscillations. They found discrepancies between the expected number of neutrinos for each flavor and what actually happened.