Neutrinos are enigmatic subatomic particles produced by a number of nuclear reactions. Their moniker, “small neutral one,” relates to the fact that they are electrically neutral. Neutrinos interact with just two of the four fundamental forces in the universe: gravity and the weak force, which is responsible for atom radioactive decay. They travel across the galaxy at almost the speed of light because they have practically little mass.

Thousands of neutrinos appeared fractions of a second after the Big Bang. New neutrinos are formed all the time: in the nuclei of stars, in particle accelerators and atomic reactors on Earth, during supernova explosions, and when radioactive materials decay. According to physicist Karsten Heeger of Yale University in New Haven, Connecticut, there are 1 billion times more neutrinos than protons in the cosmos on average.

Neutrinos, despite their widespread presence, are mostly unknown to physicists due to their difficulty in catching them. Neutrinos pass through most stuff as if they were light rays passing through a clear window, barely interacting with anything else. At this moment, almost 100 billion neutrinos are going through every square centimeter of your body, but you won’t feel a thing.

Finding particles that aren’t visible

Neutrinos were initially proposed as a solution to a scientific conundrum. Researchers in the late 1800s were perplexed by a phenomena known as beta decay, in which an atom’s nucleus spontaneously produces an electron. Beta decay appeared to defy two fundamental physics laws: energy conservation and momentum conservation. The final configuration of particles in beta decay appeared to have somewhat too little energy, and the proton remained stationary rather than being pushed in the opposite direction of the electron. Wolfgang Pauli, a scientist, didn’t suggest the concept that an additional particle may be flying out of the nucleus, carrying the missing energy and momentum until 1930.


“I’ve done something heinous. I’ve proposed a particle that is undetectable “Pauli told a friend that his proposed neutrino was so light that it would scarcely interact with anything and have very little mass.

Clyde Cowan and Frederick Reines, physicists at the atomic Savannah River power station in South Carolina, created a neutrino detector and installed it outside the nuclear reactor more than a quarter-century later. Cowan and Reines excitedly sent Pauli a telegraph informing him of their confirmation after their experiment snagged a handful of the hundreds of billions of neutrinos shooting from the reactor. Reines went on to receive the Nobel Prize in Physics in 1995, after Cowan had passed away.

Neutrinos, on the other hand, have consistently defied scientists’ assumptions since then.

The sun emits massive amounts of neutrinos, which bombard the Earth. Researchers created detectors to look for these neutrinos in the mid-twentieth century, but their results were inconsistent, with only approximately one-third of the neutrinos anticipated being detected. Either the astronomers’ models of the sun were incorrect, or something weird was occurring.

Neutrinos are thought to come in three flavors, or sorts, according to physicists. The electron neutrino is the most common type of neutrino, although there are two more types: muon neutrinos and tau neutrinos. Neutrinos oscillate between these three sorts as they transit over the distance between the sun and our planet, which is why early studies that were solely designed to look for one flavor kept missing two-thirds of their total quantity.

However, only particles with mass may oscillate, contradicting previous assumptions that neutrinos were massless. While the weights of all three neutrinos are unknown, investigations have revealed that the heaviest of them must be at least 0.0000059 times less than the mass of the electron.

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Neutrinos have new rules?

In 2011, researchers at the Oscillation Project with Emulsion-tRacking Apparatus (OPERA) experiment in Italy made headlines across the world when they announced that they had discovered neutrinos moving faster than the speed of light, which was previously thought to be impossible. Despite being extensively covered in the media, the findings were met with skepticism by the scientific community. Less than a year later, scientists discovered that defective wiring had misled them into believing they had discovered a faster-than-light particle, and neutrinos were relegated to the domain of cosmically law-abiding particles.

However, there is still a lot that scientists don’t know about neutrinos. Researchers from Fermi National Accelerator Laboratory’s (Fermilab) Mini Booster Neutrino Experiment (MiniBooNE) in Chicago have revealed persuasive evidence that they’ve discovered a new sort of neutrino termed a sterile neutrino. This confirms an earlier anomaly discovered at the Liquid Scintillator Neutrino Detector (LSND), a Los Alamos National Laboratory experiment in New Mexico. Because sterile neutrinos do not fit into the Standard Model, a framework that describes practically all known particles and forces except gravity, they would upend all of known physics.

If MiniBooNE’s latest findings are confirmed, “that would be big; that’s beyond the Standard Model; it would need new particles… and a whole new analytical framework,” according to Duke University particle physicist Kate Scholberg.

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