The nature of Neutrinos

If you've gone through basic science, you probably understand that everything in our universe made of matter is, at the base level, made of atoms. For many years these were thought of as the smallest thing you could get, but today, you are probably taught that atoms are made of smaller particles called protons, neutrons, and electrons. You can call these subatomic particles. However, this is not the smallest you can go. Protons and neutrons are made up of quarks. These, along with electrons and many others, are known as elementary particles.

These particles are often grouped together into a theory known as the standard model. However, this model is incomplete, and to finish it would be one of the greatest scientific discoveries ever. To understand this, the conflict between general relativity and quantum physics should be explained. In 1915, Albert Einstein published his theory of gravitation, known as the general theory of relativity. This theory replaced Newton's law of universal gravitation, which served as the working theory of gravity for many years. It still works today as an efficient way to approximate gravity and its effects. Despite this, Einstein's new theory overtook it as the "correct" way of thinking about gravity. It tells us that instead of gravity being a force, it is actually the curvature of spacetime. 

To understand this, imagine a trampoline. Placing a bowling ball on the trampoline (and hoping you have a strong trampoline) will cause it to bend the whole trampoline around it. Now, if you take something like a marble and place it on the trampoline, it will roll toward the bowling ball, just as a planet will move toward a star. If you really want to see this example and are up for a ten-minute watch, I recommend this video: https://www.youtube.com/watch?v=MTY1Kje0yLg

Our conflict here arises from the fact that Einstein's gravity describes large-scale things very accurately, but when it comes time to understand the small parts of the universe, the subatomic parts, this breaks down. Quantum mechanics is the field that deals with these subatomic parts of the universe. It deals with the quarks and electrons I referred to earlier, and an essential part of it is that the forces of the universe are actually carried by these subatomic particles. You may know that gravity is an inherent part of the universe, a fundamental force, but there are actually 3 more. The strong force, weak force, and electromagnetic force are all fundamental forces, and according to quantum mechanics, they are carried by particles. However, Einstein's gravity clashes with this idea. 

To understand and explain this intersection, often called Quantum Gravity, would be a monumental discovery. This idea even has its own name, the theory of everything. There have been attempts at finding this, a notable one being string theory, but most of these cannot be proven, or fall apart when attempting to describe gravity. 

To circle back to our beginnings, the standard model describes the elementary particles but cannot describe gravity as it does for the other fundamental forces. Perhaps the least understood subatomic particle is the neutrino. Neutrinos are tiny particles with almost no mass, and they zip around the universe extremely fast, barely interacting with the world. The fact that they cannot be measured electromagnetically, meaning they can't be seen by normal methods, along with their near-zero mass, makes them nearly impossible to interact with. However, a recent discovery from Ohio State University tells us that supernovae, massive explosions from dying stars, could be used to tell us about the subatomic neutrinos. 

For many years, the nature of interactions between neutrinos has remained a mystery. But recently, by measuring the neutrinos in supernovae, we have been able to predict that neutrinos actually interact with each other and form some kind of fluid. This tells us that neutrinos actually do work together in some way, which is important considering that there are more neutrinos than atoms in our universe. Additionally, understanding how neutrinos interact allows us to learn more about the supernovae which we revealed the nature of neutrinos to us in the first place. 

This understanding is the start of a solution to a mostly untouched mystery in science, and it turns out that while the large and small parts of our universe are often in conflict, they can be used to learn more about each other and understand our world better. Continuing to pursue the connection between the two sides of our universe may one day reveal the theory of everything.

Sources:

https://www.sciencedaily.com/releases/2023/08/230815151134.htm

https://en.wikipedia.org/wiki/Standard_Model

https://en.wikipedia.org/wiki/General_relativity

https://en.wikipedia.org/wiki/Neutrino

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