Neutrinos, generally referred to as nature’s ghost particles, are fermions which were first
postulated in 1930 by Wolfgang Pauli to explain the conservation of energy, momentum and spin in Beta decay. From the day of their discovery itself, they have baffled everyone due to their unique properties. Though they are quite abundant in nature, they are still not understood completely even after 90 years of their postulation. So here are 8 interesting facts about neutrinos – nature’s ghost particles.
1. Abundance of Neutrinos
Neutrinos are the second most abundant particles in the universe after photons. The
sun sends 65 billion neutrinos per second per square centimeter to earth. So about 100
trillion of them pass through the human body every second. The sun acts as a neutrino factory. Sun produces energy in its core via nuclear fusion. The nuclear reaction that takes place in the core of the Sun is known as the PP chain. In this process, two protons come together and form deuterium, giving off positrons and neutrinos (the electron neutrinos) as shown.
2. The Mass of Neutrinos
One of the most astonishing facts about neutrinos is their mass. When Pauli first gave his theory about the neutrinos, he assumed them to be massless. But later, new theories were published that assigned a small yet finite mass to these particles. According to the latest report published in Scientific American, the upper limit of neutrino mass is 0.086 electron volt, or 0.00000000000000000000000000000000000015 kilogram—making it at least six million times lighter than an electron. Despite being the lightest particles in the universe, they account to 20% of the total mass of the universe.
3. The Neutrino Oscillation
There are three types of neutrinos — or three flavors in technical terms: the electron neutrinos, muon neutrinos and tau neutrinos. As a neutrino travels along, it can switch in between these flavors, acting like a chameleon changing colors. This is known as the neutrino flavor oscillation: a phenomenon that solved the long standing solar neutrino puzzle.
The concept of neutrino oscillation has another important implication. Neutrinos change their flavor with a particular frequency. This means they have an ‘intrinsic clock’ according to which they change their flavor. So they aren’t frozen in time. Then according to special relativity, they must have a finite mass. This is yet another argument that neutrinos aren’t massless. The concept of neutrino oscillation, however, isn’t present in the standard model of particle physics.
4. The Force of Interaction
There are four fundamental forces in nature: strong, weak, electromagnetic and
gravitational force. Neutrinos are the only particles found to solely interact through the weak force. Hence, they play a vital role in digging into the details of the weak force. The behavior of neutrinos and anti-neutrinos is important in the study of particle physics.
5. Extent of Neutrino Interaction
Both photons and neutrinos are created inside the core of stars. But while photons
take tens of thousands of years to reach the edge of the sun, neutrinos make this trip in
just 3.2 seconds. This is because the latter interact quite feebly with matter. Trillions of neutrinos pass right through the Earth each second hardly interacting with it. This is one of the most interesting facts about neutrinos.
6. Detection of Neutrinos
Neutrinos are hard to detect. On an average, only one neutrino from the sun will interact
with a person’s body during his or her life time. The largest neutrino detector in operation today is Super Kamiokande-III in Japan, which houses 50,000 tones of water to interact with neutrinos.
7. Role In Supernovae
These particles dissipate about 99% of the total supernova’s energy. If Betelgeuse goes supernova today, Super Kamiokande-III would detect an estimated 13 million neutrinos. So the supernovae are very important astrophysical events to study the properties of these ghostly particles. Neutrinos will act as a warning signal before the supernova of Betelgeuse. The Earth will be bombarded with a burst of neutrinos from Betelgeuse just hours before the supernova. This will help us gain time to point our telescopes at the exploding Betelgeuse.
8. Neutrinos and Dark Matter
These high velocity particles are also proposed candidate for hot dark matter, as they do not emit or absorb light, making them appear dark.
These interesting facts about neutrinos are what makes them the ghost particles of the universe. Neutrinos are the hot topic of research, both in astrophysics and particle physics. Neutrino Astrophysics is an emerging field of scientific research and there is a lot to discover.