From UPSC perspective, the following things are important :
Prelims level : Neutrinos
Mains level : NA
Indian scientists have shown that the geometry of space-time can cause neutrinos to oscillate.
What are Neutrinos?
- A neutrino is a subatomic particle that is very similar to an electron but has no electrical charge and a very small mass, which might even be zero.
- Since neutrinos are electrically neutral, they are not affected by the electromagnetic forces which act on electrons. Hence, they are also called Ghost Particles.
- Neutrinos are affected only by a “weak” sub-atomic force of a much shorter range than electromagnetism and are therefore able to pass through great distances in matter without being affected by it.
- They are also one of the most abundant particles in the universe. As they have very little interaction with matter, however, they are incredibly difficult to detect.
Answer this PYQ in the comment box:
Q.The known forces of nature can be divided into four classes, viz, gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
(a) Gravity is the strongest of the four
(b) Electromagnetism act only on particles with an electric charge
(c) Weak nuclear force causes radioactivity
(d) Strong nuclear force holds protons and neutrons inside the nuclear of an atom
Finding of the new research
- Neutrinos are mysterious particles, produced copiously in nuclear reactions in the Sun, stars, and elsewhere.
- They “oscillate”- meaning that different types of neutrinos change into one another – as has been found in many experiments.
- Probing of oscillations of neutrinos and their relations with mass are crucial in studying the origin of the universe.
- Neutrinos interact very weakly with everything else – trillions of them pass through every human being every second without anyone noticing.
- A neutrino’s spin always points in the opposite direction of its motion, and until a few years ago, neutrinos were believed to be massless.
What makes this possible?
- The geometry of space-time can cause neutrino oscillations through quantum effects even if neutrinos are massless.
- Einstein’s theory of general relativity says that gravitation is the manifestation of space-time curvature.
- Neutrinos, electrons, protons and other particles which are in the category of fermions show a certain peculiarity when they move in presence of gravity.
- Space-time induces a quantum force in addition to gravity between every two fermions.
- This force can depend on the spin of the particles and causes massless neutrinos to appear massive when they pass through matter, like the Sun’s corona or the Earth’s atmosphere.
- Something similar happens for electroweak interactions, and together with the geometrically induced mass, it is enough to cause oscillation of neutrinos.