It crashed in Antarctica after travelling at the speed of light. It stuck in the ice. It wasn’t an asteroid or an extraterrestrial spaceship, but a neutrino, a particle that only rarely interacts with matter.
Neutrinos, while being postulated in the 1930s and first detected in the 1950s, have a mysterious air about them and are sometimes referred to as “ghost particles”: they are neither haunted nor threatening, but merely move through the Earth without our notice. “And that’s a good name.” According to astronomer Clancy James of Curtin University in Western Australia.
For the past few years, ghost particles have been in the news for a variety of reasons, not just because they have a funny name. Other neutrinos appear to be entering from above the Sun, and this collision in Antarctica has been linked to a black hole ripping a star apart. Physicists were able to directly estimate the approximate mass of a neutrino in early 2022, a discovery that might lead to the discovery of undiscovered physics or the breaking of the standard model’s principles.
Imagine catching a ghost and being able to identify it belonged to someone who had passed away. It would fundamentally alter our understanding of the universe. For the same reason, a ghost particle is a major issue, which is why astrophysicists are attempting to trap it. You’re ecstatic, so you should be as well.
What is a neutrino, exactly?
In a brief, a neutrino is a basic subatomic particle. It is classed as a “lepton” in the standard model of particle physics. Electrons, the negatively charged particles that make up atoms, as well as protons and neutrons, are other leptons. But, if we break it all down, we’ll truly get into particle physics, and it’ll blow our minds off.
The neutrino is unusual in that it has a very low mass and no electrical charge, and it can be found everywhere around the cosmos. “They’re created in the sun, nuclear reactors, and when high-energy cosmic rays collide with Earth’s atmosphere,” explains Eric Thrane, an astronomer at Monash University in Australia. They are also formed by some of the most extreme and powerful phenomena we know of, such as supermassive black holes and exploding stars, and they were also produced during the Big Bang, the beginning of the universe.
They effectively travel in a straight path from where they were produced in space, similar to light. Other charged particles are affected by magnetic fields, while neutrinos, like a phantom bullet launched from a giant cosmic weapon, fly across space unaffected.
Hundreds of billions of them are whizzing through the earth and into you as you read this.
They’re crashing into us right now?
Yes, it is correct. Neutrinos flow through your body every second of every day since the day you were born. They just aren’t aware of it since they don’t engage with anything. They don’t make contact with the atoms that make you up, so you have no idea they’re there. The neutrino moves directly, like a dark ghost passing through a wall. Fortunately, there is no need for an exorcism.
But why should I be concerned with neutrinos?
Scientists have been surprised by the results of their decades of research. Neutrinos should have no mass, according to the Standard Model. They do, though. “The fact that they’re doing it suggests new physics to help us better comprehend the cosmos,” James explains.
In the 1960s, the enigma of neutrino mass arose. According to scientists, the sun must create electron neutrinos, which are a sort of subatomic particle. That, however, was not the case. This “solar neutrino dilemma” has resulted in a ground-breaking discovery: neutrinos have the ability to affect flavour.
The ghost particle comes in just three flavours, similar to an almost empty bag of Mentos: Electron, Muon, and Tau, and they can change flavours as they wander across space (flavour is the current nomenclature; I’m not going to break it down). only on the basis of this comparison). The sun, for example, may create an electron neutrino, which would subsequently be detected as a muon neutrino.
As a result of this alteration, the neutrino now possesses mass. They couldn’t modify the flavour if they didn’t have mass, according to physics. The goal of current research is to figure out what mass is.
Researchers discovered that the mass of a neutrino is exceedingly low in a study published in the prominent magazine Nature in February 2022. (but it exists). Physicists in Germany used a neutrino detector to demonstrate that a neutrino’s maximal mass is roughly eight-tenths of an electron volt (eV). It has a very low mass, more than a million times that of an electron.
Wait! Is there a neutrino detector? Aren’t they, however, ghost particles? How do neutrinos become detected?
“Damn things generally run right past any detector you make!” says James.
However, there are various methods for capturing a ghost.
One of the most critical components you’ll need is space. Deep underground, in physical space. The scientists installed their neutrino detectors in Antarctica under meter-high ice and subsequently on the ocean floor to achieve great findings. This protects the data from things like cosmic rays, which would otherwise blast delicate instruments on the surface. IceCube, the detector in Antarctica, is buried at a depth of around 8,000 feet.
It’s possible that “catching” a ghost particle isn’t the most accurate description of what these detectors perform. For example, IceCube does not capture neutrinos. Typically, the particles are fired straight into the detector. However, some of them come into contact with Antarctic ice on a very (very!) infrequent basis, resulting in a shower of secondary particles that generate Cherenkov radiation, a sort of blue light. The light produced by these particles is captured by a series of photosensitive spherical modules placed vertically like beads on a string. Super-Kamiokande, a Japanese detector, is comparable. This one is located beneath Mount Ikeno and employs a 55,000-ton water tank instead of ice.
They are both aware of where the neutrino came from and what it is capable of. As a result, scientists may detect evidence of the presence of the ghost particle but not the ghost particle itself. It’s like a poltergeist in that you can see him interact with chairs (throwing them at you) and lights (threatening you and turning them off), but you can’t see the ghost itself. Sinister!
Impressive. So, what can neutrinos teach us?
Neutrinos are basic particles in our cosmos, meaning they underpin everything. Learning more about neutrinos can help to solve some of physics’ puzzles.
“Neutrinos are studied by particle physicists for hints to physics beyond the Standard Model,” Thrane explains. He points out that physicists want to know if neutrinos violate any of the Standard Model’s fundamental rules. “It might offer some insight on why there is more matter in the cosmos than antimatter,” Thrane adds, noting that the topic has been dubbed one of physics’ great mysteries.
We also know that they can be caused by severe cosmic objects and occurrences. For example, neutrinos are known to be produced and propelled across the cosmos by exploding stars or supernovae. Supermassive black holes, like supermassive black holes, consume gas, dust, and stars.
“Neutrino detection reveals what is happening inside these things,” James explains.
We could utilise neutrinos to observe and understand these items in parts of the cosmos that we can’t examine with other electromagnetic frequencies because they scarcely interact with surrounding matter (such as optical, UV, and radio light). Scientists may, for example, examine the Milky Way’s core, which is impossible to observe at other electromagnetic wavelengths due to gas and dust.
Reliable detection and monitoring of gravitational waves might spark an astronomical revolution akin to what we’re experiencing now. Neutrinos, in essence, can provide us with a completely new perspective on the universe, augmenting our existing telescopes and detectors to disclose what’s going on in the vacuum.
Then there are the neutrinos that are “sterile.”
What are sterile neutrinos, and how do they work?
I probably should have kept it a secret, but since you’re here, you should know that sterile neutrino are a different type of neutrinos. They are purely hypothetical, yet scientists assume they exist because of chirality, a physical property. The typical neutrinos we’ve been discussing are referred to as “lefties” by some. As a result, some physicists believe that “right-handed” neutrinos, or sterile neutrinos, may exist.
They are given this name because, unlike conventional neutrinos, they do not interact with other particles via weak force. Gravity is the only thing that brings them together. This sort of neutrino is thought to be dark matter, which accounts for more than a quarter of the cosmos yet has never been seen.
As a result, neutrinos may be able to assist in the resolution of another enigma in physics: the nature of dark matter. There have been numerous dark matter theories proposed by physicists, and there is still more to discover; it may or may not be related to neutrinos!
Cool. Is there anything more regarding neutrinos that I should know?
“It’s only the beginning, but I’ve lost my mind,” As Deborah Conway sang.
Some of the most damning neutrino hypotheses, such as neutrinoless double-beta decay and the concept of the neutrino as a Majorana particle, have yet to be considered.
The Giant Radio Array for Neutrino Detection, or GRAND, is one of several new neutrino experiments suggested, with up to 200,000 receivers. The network’s entire area is about the same size as the United Kingdom. In the next years, the first 10,000 antennas are scheduled to be placed on the Tibetan Plateau near Dunhuang.
Although just a few neutrinos have been detected and tracked thus far, neutrino astronomy is expected to take off in the next decade. The bottom line is that knowing neutrinos, their flavours, and their masses will give insight into the nature of our world at its most fundamental level.
It’s also fun to go ghost hunting.