(GS Paper 3) Achievements of Indians in science & technology (Part 1)

Achievements of Indians in science & technology (Part 1)

Chandrasekhara Venkata Raman (1888-1970) (Nobel Prize for Physics in 1930)

  • C V Raman acquired his BA degree from the Presidency College, Madras, where he carried out original research in the college laboratory, publishing the results in the philosophical magazine. Then went to Calcutta and while he was there, he made enormous contributions to vibration, sound, musical instruments, ultrasonics, diffraction, photo electricity, colloidal particles, X-ray diffraction, magnetron, dielectrics and the celebrated Raman effect which fetched him the Noble Prize in 1930.
  • He was the first Asian scientist to win the Nobel Prize.

Raman Effect or Raman Scattering

  • Light scattering can be thought of as the deflection of a ray from a straight path, for example by irregularities in the propagation medium, particles, or in the interface between two media.
  • Raman Scattering is change in the wavelength of light that occurs when a light beam is deflected by molecules. When a beam of light traverses a transparent sample of a chemical compound, a small fraction of the light emerges in directions other than that of the incident (incoming) beam. Most of this scattered light is of unchanged wavelength. A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman effect.
  • The phenomenon is named for Indian physicist Sir C V Raman, who first published observations of the effect in 1928.
  • Raman scattering is perhaps most easily understandable if the incident light is considered as consisting of particles, or photons, that strike the molecules of the sample. Most of the encounters are elastic, and the photons are scattered with unchanged energy and frequency. On some occasions, however, the molecule takes up energy from or gives up energy to the photons, which are thereby scattered with diminished or increased energy, hence with lower or higher frequency. The frequency shifts are thus measures of the amounts of energy involved in the transition between initial and final states of the scattering molecule.
  • Intensity of Raman scattered light is very weak.

What is difference between raman scattering and rayleigh scattering?

  • Rayleigh scattering is elastic while Raman is inelastic scattering.
  • For Raman scattering, the atom or molecule goes from the state 1 to a virtual level 2 while absorbing a photon, and then goes to level 3, which is a totally different level of 1, and emit anther photon. The frequencies of the absorbed and emitted photon is changed. So this is an inelastic scattering.
  • For Rayleigh scattering, that atom goes form 1 to the level 2, which is still a virtual level and end in level 1, that’s the exact level which the atoms used be on. The frequencies of the absorbed and emitted photon are the same. So this is an elastic scattering.
  • In Rayleigh, no energy is lost. Incoming light’s wave length and scattered light wave length will be same. This is very good at small wavelengths.. In Raman, energy is lost (i.e., inelastic process). Very small (1 in 10000000 photon) will suffer Raman scattering. Remaining is Rayleigh scattering. Raman effect makes the molecules to rotate/excite. Also since this is very small and so one cannot say blue color of sky is due to Raman effect.

What is the difference between Raman scattering and fluorescence?

  • Both phenomena involve the emission of photons shifted in frequency relative to the incident light.
  • Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence (Luminescence is emission of light by a substance not resulting from heat. This distinguishes luminescence from incandescence, which is light emitted by a substance as a result of heating.)
  • In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation.
  • The Raman effect, which is a light scattering phenomenon, should not be confused with absorption (as with fluorescence) where the molecule is excited to a discrete (not virtual like Raman) energy level.

Hargobind Khorana (1922-2011)  (Nobel Prize for Medicine and Physiology in 1968)

  • Hargobind Khorana was responsible for producing the first man made gene in his laboratory in the early seventies. This historic invention won him the Nobel Prize for Medicine in 1968 sharing it with Marshall Nuremberg and Robert Holley for interpreting the genetic code and analyzing its function in protein synthesis.
  • They all independently made contributions to the understanding of the genetic code and how it works in the cell. They helped to show how the order of nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins.
  • He had left India in 1945 and became a naturalized United States citizen in 1970. He continued to head a laboratory at the Massachusetts Institute of Technology (MIT) in United States, until his death in 2011.

Subramaniam Chandrasekhar (1910-1995) (Nobel Prize for Physics in 1983)

  • Subramaniam Chandrashekhar’s paternal uncle was the Indian physicist and Nobel laureate C. V. Raman. Chandrasekhar was a astrophysicist andserved on University of Chicago faculty from 1937 until his death in 1995. He became a naturalized citizen of the United States in 1953.
  • His work spanned over the understanding of the rotation of planets, stars, white dwarfs, neutron stars, black holes, galaxies and clusters of galaxies. He won the Nobel Prize in 1983 for his theoretical work on stars and their evolution.

Chandrasekhar Limit

  • Chandrasekhar limit is maximum mass theoretically possible for a stable white dwarf star. (White dwarfs are thought to be the final evolutionary state of stars whose mass is not high enough to become a neutron star)
  • This limiting value was named after Subrahmanyan Chandrasekhar, who formulated it in 1930 at the age of 19 in India.
  • Using Albert Einstein’s special theory of relativity and the principles of quantum physics, Chandrasekhar showed that it is impossible for a white dwarf star, which is supported solely by a degenerate gas of electrons, to be stable if its mass is greater than 1.44 times the mass of the Sun.
  • All direct mass determinations of actual white dwarf stars have resulted in masses less than the Chandrasekhar limit. A star that ends its nuclear-burning lifetime with a mass greater than the Chandrasekhar limit must become either a neutron star or a black hole.

Venkatraman Ramakrishnan (1952 – ) (Nobel Prize for Chemistry in 2009)

  • Venkatraman Ramakrishnan was an Indian born American and British structural biologist, who shared the Nobel Prize in 2009 in Chemistry with Thomas A. Steitz and Ada E. Yonath for studies of the structure and function of the ribosome.
  • He received India’s second highest civilian honor, the Padma Vibhushan, in 2010.
  • He currently works at the MRC Laboratory of Molecular Biology in Cambridge, England and now a US Citizen. On November 30, 2015, Ramakrishnan will take up the post of President of the Royal Society.
  • Research in Ribosome: His work has helped scientists to understand the structure of the ribosome at an atomic level. Ramakrishnan has managed this by using the process of X-ray crystallography. Using this, he was able to map the position of every atom that makes up the ribosome.

Jagadish Chandra Bose (1858 – 1937)

  • J C Bose was an Indian polymath, physicist, biologist, biophysicist and botanist. He pioneered the investigation of radio and microwave optics, made very significant contributions to plant science, and laid the foundations of experimental science in the Indian subcontinent.
  • IEEE named him one of the fathers of radio science. He also invented the crescograph. A crater on the moon has been named in his honour.
  • Bose’s Radio: In 1895, J.C. Bose made a public demonstration, in presence of the Lt. Governor of Bengal, of wireless radio. However, his discovery was mostly ignored, and the credit went to Marconi, who made a demonstration in 1897. However, scientists around the world now acknowledge him as the true pioneer. (There’s another Bose – Amar Bose – who is also famous for advances in speaker and radio technology).
  • Research into Plant Intelligence: J.C. Bose switched his attention to plants, and how they respond to stimuli. How do they respond to the sun’s movement through the day? How do they react to wounds, pesticides, insects etc? He discovered that electrical signals passed between plant cells, making him wonder whether they had a nervous system. He invented a machine called the crescograph to study all this. He also discovered that they grew well if exposed to pleasant music.

Satyendra Nath Bose (1894 – 1974)

  • SC Bose was an Indian physicist specialising in mathematical physics. He is best known for his work on quantum mechanics in the early 1920s, providing the foundation for Bose–Einstein statistics and the theory of the Bose–Einstein condensate. A Fellow of the Royal Society, he was awarded India’s second highest civilian award, the Padma Vibhushan in 1954 by the Government of India.
  • BoseEinstein Condensate: In ordinary physics, each particle is distinct from each other. You can track each particle. This is true of all big and small things like planets, rubber balls and even grains of dust. But when we go into smaller scales, like subatomic particles (like electrons), the ordinary rules don’t apply. The particles become indistinguishable, and so we cannot track them. This is the realm of quantum physics.
  • S.N. Bose and Albert Einstein together developed many of the principles that apply in quantum physics. These are together known as BoseEinstein Statistics. While this science is quit difficult, it makes an interesting prediction. It says that atoms, when cooled to a temperature close to absolute zero (273.15 degree C), will collapse into a new state of matter. This is called the BoseEinstein Condensate (BEC).
  • Many people thought BEC was just an idea, since it was near impossible to make. The first BEC took seventy years to make after Bose’s paper. In 1995, Eric Cornell and Carl Wieman, of the University of Colorado cooled rubidium atoms to very near absolute zero. Their detector indicated the formation of a BEC, proving Bose & Einstein correct.
  • Bosons: Particles that obey Bose Einstein statistics are called bosons which was named after S N Bose. These include particles like photons and mesons. You can track a single atom, but never a single photon. In fact a photon can at the same time exist in two places. Two photons can exchange places without moving at all.
  • When you are making a Bose Einstein Condensate all the individual atoms disappear. Instead what you get are the subatomic particles, all becoming bosons. So whatever substance you make a BEC out of, all BECs are exactly the same – a collection of bosons.
  • Higgs boson: One kind of boson is the Higgs boson. It is described by physicists in theory, but none has ever seen one yet. So physicists have built a huge special machine called the Large Hadron Collider. It is a circular tunnel 27 km underneath the Swiss mountains, and cost $ 9 billion to build. All to find a tiny particle

Higgs Boson / God Particle:

  • The “God particle” is the nickname of a subatomic particle called the Higgs boson.The “God particle” nickname actually arose when the book The God Particle: If the Universe Is the Answer, What Is the Question? by Leon Lederman was published.
  • Different subatomic particles are responsible for giving matter different properties. One of the most mysterious and important properties is mass. Some particles, like protons and neutrons, have mass. Others, like photons, do not. The Higgs boson, or “God particle,” is believed to be the particle which gives mass to matter.
  • In the Standard Model, the Higgs particle is a boson (a particle that follows Bose–Einstein statistics) with no spin, electric charge, or colour charge.
  • The Higgs boson is an elementary particle in the Standard Model of particle physics. (Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, as well as classifying all the subatomic particles known). The Higgs is the last missing piece of the Standard Model, the theory that describes the basic building blocks of the universe. The other 11 particles predicted by the model have been found and finding the Higgs would validate the model (now found).
  • Its main relevance is that it allows scientists to explore the Higgs field – a fundamental field that unlike the more familiar electromagnetic field cannot be “turned off”, but instead takes a non-zero constant value almost everywhere. Higgs field has been proposed as the energy of the vacuum, which at the extreme energies of the first moments of the Big Bang caused the universe to be a kind of featureless symmetry of undifferentiated extremely high energy. The presence of this field explains why some fundamental particles have mass even though the symmetries controlling their interactions should require them to be massless, and also answers the reason the weak force has a much shorter range than the electromagnetic force.

What is the Large Hadron Collider?

  • Despite being present everywhere, the existence of the Higgs field is very hard to confirm. It can be detected through its excitations (i.e. Higgs particles), but these are extremely hard to produce and detect. The importance of this fundamental question led to a 40 year search for this elusive particle, and the construction of one of the world’s most expensive and complex experimental facilities to date, CERN’s Large Hadron Collider, able to create Higgs bosons and other particles for observation and study. On 4 July 2012, the discovery of a new particle was announced; physicists suspected that it was the Higgs boson. By March 2013, the particle had been proven to behave, interact and decay in many of the ways predicted by the Standard Model, and was also tentatively confirmed to have positive parity and zero spin, two fundamental attributes of a Higgs boson. This appears to be the first elementary scalar particle discovered in nature.
  • The Large Hadron Collider is the world’s biggest and most powerful particle accelerator, a 27-km looped pipe that sits in a tunnel 100 metres underground on the Swiss/French border.
  • Two beams of protons are fired in opposite directions around it before smashing into each other to create many millions of particle collisions every second in a recreation of the conditions a fraction of a second after the Big Bang, when the Higgs field is believed to have ‘switched on’.
  • Of all the trillions of collisions, very few are just right for revealing the Higgs particle. That makes the hunt for the Higgs slow, and progress incremental.

C.N.R. Rao (1934- )

  • C.N.R. Rao is an Indian chemist who has worked mainly in solid-state and structural chemistry. He currently serves as the Head of the Scientific Advisory Council to the Prime Minister of India.
  • In 2013, the Government of India gave to for CNR Rao, Bharat Ratna, the highest civilian award in India, making him the third scientist after C.V. Raman and A. P. J. Abdul Kalam.

A. P. J. Abdul Kalam (1931 – 2015)

  • A. P. J. Abdul Kalam was a scientist and science administrator, mainly at the Defence Research and Development Organisation (DRDO) and Indian Space Research Organisation (ISRO) and was intimately involved in India’s civilian space program and military missile development efforts. He thus came to be known as the Missile Man of India for his work on the development of ballistic missile and launch vehicle technology.
  • He also played a pivotal organizational, technical, and political role in India’s Pokhran-II nuclear tests in 1998, the first since the original nuclear test by India in 1974.

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