Neutrinos: Nature’s Ghost Particles
The subatomic world is full of eccentric particles, each one with their respective personalities and behaviors. However, one of them is particularly mysterious. This class of particles is called the neutrinos. These are the ghosts of the subatomic world. They interact very less as compared to other known particles, in fact, something like 650 trillion of them are hitting you every second yet it took thirty years to prove that they exist, so let me tell you their story.
It began in the 20th century when physicists first calculated the energy of atoms precisely. They were startled by the fact that it violated the law of conservation of energy. They found out that during a radioactive decay when an electron is ejected from an element to form another element, the energy of the escaped electron plus that of the new element was less than the energy of the original element.
But the law stated,
“thou shall not destroy or create energy”
So, where did the missing energy go?
In 1930, Wolfgang Pauli predicted that there must be some undiscovered particle that is responsible for the missing energy. A generation later, Pauli’s neutrinos were detected in the radiation from a nuclear reactor.
Talking about nuclear reactors, let’s look at the best nuclear reactors in the universe, the stars. When they undergo cataclysmic supernova explosions, their brightness rivals that of their entire galaxy. But all that light is only 1% of the energy liberated in the explosion and the rest of the energy is carried off by the most mysterious particles in the cosmos. There are trillions of them passing through you right now, and tracking down even one of them will take you to the strangest places on earth.
Stalking wild neutrinos is the rarest sport. Welcome to the Super Kamiokande, the subterranean Japanese neutrino detection chamber. You might ask,”who in their right minds would bury an astronomical observatory?”, those who hunt the most elusive prey in the cosmos-the neutrinos-will.
The observatory has an enormous array of light detectors surrounding 50,000 tons of distilled water used as a trap designed to catch only neutrinos. Other particles such as cosmic rays cannot get through all that rock above it, whereas a neutrino could pass through 100 light years of steel without even slowing down. On a rare occasion when it actually does interact with ordinary matter, it produces a flash of light.
The Large Magellanic Cloud is a neighboring galaxy which is visible in the skies of the Southern Hemisphere. When a supernova in the Large Magellanic Cloud took place in 1987, the neutrinos didn’t come through that half mile above the Kamiokande detector but had to pass through thousands of miles of rocks and iron below, but the coolest thing was that those neutrinos hit earth 3 hours before the light from the supernova.
If nothing can travel faster than light, then how could it be possible?
Neutrinos produced in the heart of an exploding sun race outward nearly at light speed in a few seconds, but the shock waves of exploding gas move from the center of the star at 1/10000 the speed of light until it finally reaches the surface. It takes hours for the explosion to reach the surface. The neutrinos had an early start that’s why the light came so much later than the shower of neutrinos.
Why are neutrinos important?
They are one of the universe’s essential ingredients, and they have played a role in helping scientists understand some of the most fundamental questions in physics. Neutrinos help in our understanding of the kind of processes that go on in the sun and also they are an important building block for the blueprint of nature.
Feeling the sun on your face? The energy that warms you began its journey some ten million years ago in the heart of the sun. Unlike neutrinos, photons needed that long to reach the surface from the core of the sun.
Ten-million-year-old-light…Why?
Because they were colliding billions of times per second with surrounding atoms and thus moving in random directions before reaching the surface of the sun, this process took millions of years.
Imagine that all the matter and energy of the universe concentrated to something the size of a marble. That’s the size of the universe when it was a trillionth of a trillionth of a trillionth of a second old. Can you imagine how tightly packed that marble must have been?
The Big Bang must have produced a stupendous number of neutrinos which flow unhindered through matter and thus almost impossible to detect, this is what allows neutrinos to sail through the curtains that conceal the beginning of time. The fact that neutrinos are unaffected by ordinary matter interests scientists who are trying to find a way to ride those neutrinos all the way back to the beginning of time.
Where are they now?
They are here, they are there, everywhere throughout the universe. Neutrinos from creation are within you.
From a marble…to the cosmos.
