Type: Prelims Only

National Science Day is commemorated on Feb 28 every year to commemorate the bird anniversary of Sir CV Raman.

National Science Day

• In 1986, the Government of India, under then PM Rajiv Gandhi, designated February 28 as National Science Day to commemorate the announcement of the discovery of the “Raman Effect”.
• The Raman Effect was the discovery which won physicist Sir CV Raman his Nobel Prize in 1930.

Who was CV Raman?

• Raman conducted his Nobel-prize-winning research at IACS, Calcutta.
• While he was educated entirely in India, Raman travelled to London for the first time in 1921, where his reputation in the study of optics and acoustics was known to physicists such as JJ Thomson and Lord Rutherford.
• The Raman Effect won scientist Sir CV Raman the Nobel Prize for physics in 1930.
• It was also designated as an International Historic Chemical Landmark jointly by the American Chemical Society (ACS) and the Indian Association for the Cultivation of Science (IACS).
• His speciality was the study of vibrations and sounds of stringed instruments such as the Indian veena and tambura, and Indian percussion instruments such as the tabla and mridangam.

The Raman Effect

• In 1928, Raman discovered that when a stream of light passes through a liquid, a fraction of the light scattered by the liquid is of a different colour.
• While Raman was returning from London in a 15-day voyage, he started thinking about the colour of the deep blue Mediterranean.
• He wasn’t convinced by the explanation that the colour of the sea was blue due to the reflection of the sky.
• As the ship docked in Bombay, he sent a letter to the editor of the journal Nature, in which he penned down his thoughts on this.
• Subsequently, Raman was able to show that the blue colour of the water was due to the scattering of the sunlight by water molecules.
• By this time he was obsessed with the phenomenon of light scattering.

Observing the effect

• The Raman Effect is when the change in the energy of the light is affected by the vibrations of the molecule or material under observation, leading to a change in its wavelength.
• Significantly, it notes that the Raman effect is “very weak” — this is because when the object in question is small (smaller than a few nanometres), the light will pass through it undisturbed.
• But a few times in a billion, light waves may interact with the particle. This could also explain why it was not discovered before.
• In general, when light interacts with an object, it can either be reflected, refracted or transmitted.
• One of the things that scientists look at when light is scattered is if the particle it interacts with is able to change its energy.

Real-life applications

• Raman spectroscopy is used in many varied fields – in fact, any application where non-destructive, microscopic, chemical analysis and imaging is required.
• Whether the goal is qualitative or quantitative data, Raman analysis can provide key information easily and quickly.
• It can be used to rapidly characterize the chemical composition and structure of a sample, whether solid, liquid, gas, gel, slurry or powder.

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Central idea: The article discusses recent research on the idea that neutrinos might be their own antiparticles, a concept that has been debated in the scientific community for many years.

What are neutrinos?

• Neutrinos are fundamental particles that are similar to electrons but have no electric charge.
• They are one of the most abundant particles in the universe, but they are also one of the most difficult to detect because they interact only very weakly with matter.
• Neutrinos are created in a variety of natural processes, including nuclear reactions in stars, radioactive decay, and cosmic ray interactions.
• They are also produced in particle accelerators and nuclear reactors.

Its types

• Neutrinos come in three different types or “flavors”:

1. Electron neutrinos
2. Muon neutrinos, and
3. Tau neutrinos

• Each flavor of neutrino is associated with a different charged lepton (electron, muon, or tau).

Why study neutrinos?

• Because they are electrically neutral and interact only weakly with matter, neutrinos can pass through enormous amounts of material without being stopped or deflected.
• This property makes them useful for studying astrophysical phenomena such as supernovae and the sun’s interior, as well as for exploring the fundamental nature of matter.

Neutrinos as their own antiparticles

• Particle physics explains that particles and their antiparticles have opposite properties, and they can annihilate each other when they meet.
• Neutrinos are fundamental particles that are difficult to detect as they have no electric charge and interact only weakly with matter.
• The idea that neutrinos could be their own antiparticles is supported by the fact that they are electrically neutral, and they could interact with themselves in a process called neutrinoless double beta decay.

Substantiation of this

• The Majorana Demonstrator experiment is designed to detect neutrinoless double beta decay.
• The experiment has reported some promising results that suggest that neutrinos could indeed be their own antiparticles.

Significance of this theory

• If confirmed, the idea that neutrinos are their own antiparticles could have important implications for our understanding of the fundamental nature of matter and the universe as a whole.
• More research will be needed before any definitive conclusions can be drawn, but the results of the Majorana Demonstrator experiment provide some promising evidence for the idea that neutrinos are their own antiparticles.

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