Physics_scence and India

8/2/2019 Physics_scence and India

1/9

112 P U R S U I T A N D P R O M O T I O N O F S C I E N C E

I

ndia has more than a century old tradition of

creating and contributing to physics at the

highest level, with a very wide base today of

institutions, skills, knowledge and research

activity. In this brief overview, we try to convey asense of this experience. We then set the stage by

recalling the unique pre-Independence (1947)

contributions to physics. Some of the highlights of

physics research in India in the following half century

are then mentioned, in two parts; the period till

roughly about a decade ago, and the last ten years.

The emphasis of India's comprehensive

intellectual culture was broadly linguistic,

philosophical and literary. However, thinking about

the physical world, inventing mathematical ideasand languages, and experimentation and technology,

all have ancient roots. One example of each of the

above may be mentioned because, consciously or

not, this is one of the formative influences of

contemporary Indian activity in physics. The atomic

theory was hypothesized by Kanada (6th century

BC) who, along with Prasastapada, was the founder

of the philosophical school called Nyaya Vaiseshika

or Logical Atomism. Their argument for the

particulate nature of matter was the manifest

inequality of different bits of it; if matter were

infinitely divisible, how could a mustard seed be

unequal to the Meru Mountain ? The philosophers

of this school went on to describe diatomic and

triatomic molecules formed of elementary atoms,

thermal dissociation of molecules, and shape and

size of atoms. The Kerala School of mathematicians,

starting with Madhava in the 14th century,

discovered and used differential and integral

calculus in the course of expressing trignometric

functions as an infinite power series, obtaining the

famous series of Gregory, Newton and Leibniz and

thence a value of accurate to 11 decimals, all thistwo to three centuries before calculus was invented

in the West, in a different context, by Newton and

Leibniz. The fertile coming together of these three

kinds of activity, a hallmark of contemporary science,

did not happen and it was with the British conquest

of India that science as we know it today entered the

country. Western higher education began to be

officially sponsored and supported from the early

19th century. Towards the end of the 19th century

and the beginning of the 20th, three factors, namelythe results of this policy, resurgent national as well

as cultural consciousness, and the revolution in

physics came together to create the most remarkable

period in modern Indian science. The best known

figures of this period are icons in the contemporary

national imagination; together they gave India a

special position in the physics world. Their work

and influence are briefly mentioned here, both for

their own interest and because this is the immediate

background for physics in India.

The first, and in many ways the most unusual

was Jagadis Chandra Bose (1858-1937), a pioneer in

experimental studies of ultra-short (millimetre

wavelength) electromagnetic waves, and in the

physical response of plants to stimuli. He went to

study medicine in London in 1880, shifted to science

at Cambridge and returned to teach at Presidency

College, Kolkata. Here, in the 1890's he started

PHYSICS

C H A P T E R I X


2/9

experiments on microwaves, generating and

detecting them over distances of the order of a mile,

a year or more before Marconi's experiments on

longer wavelength radio waves. He established

their identity as transverse electromagnetic waves

with ingenious but materially simple table top

experiments, taking advantage of their millimetre

wavelength. The horn antennae, waveguides, and

the semiconductor rectifiers he developed for

detection prefigured the detailed exploration of

microwaves and the knowing use of pn junction

(silicon) rectifiers by half a century. In

the early years of the 20th century, J.C.

Bose began studying electrical and

mechanical response of plants to stress,

by devising techniques for amplifying

extremely minute movements andchanges. Clearly it was far too early to

make scientific sense of the striking

results, and their often anthropomorphic

description in a literal minded scientific

age did not help. This scientific explorer

was also a great teacher, emphasizing

demonstration and experiment.

Somewhat later came C. V. Raman

(1888-1970), the greatest of Indianscientists. Precocious (his first scientific

paper was published when he was

about seventeen), indigenous and

entirely self taught, he was the natural

scientist of the world of light and sound

waves. The first half of his career (1907-

1933) was spent in Kolkata and the

remainder in Bangalore. He is best

known for his discovery (Raman effect,

1928) that photons interacting withmatter can change their frequency, the

shift being characteristic of its internal

excitations. Prior to this, photons were known to be

fully absorbed (e.g. photoelectric effect) or scattered

elastically (ordinary or Raleigh scattering of light,

or Compton effect); these are first order processes.

The Raman effect, second order in the photon field,

is a new phenomenon probing the internal states of

molecules and of condensed matter. Some of the

other major discoveries of Raman are the origin of

the musical nature of the drums tabla and

mridangam, diffraction of light from stationary

wavefronts created by ultrasound in liquids, light

scattering from polymers and from short-lived shear

fluctuations in fluids, and the soft mode associated

with structural phase transitions in solids. Raman's

style was imaginative and incisive, doing relatively

simple but often ingenious experiments to probe

113P U R S U I T A N D P R O M O T I O N O F S C I E N C E

A typical flower texture exhibited by a columnar

liquid crystal. This mesophase was discovered in

compounds made of disc-shaped molecules in the

Raman Research Institute in 1977.


3/9

phenomena. He was primarily a research scientist

with a large number of research students over a long

(~ 40 years long) and productive scientific career;

these students helped shape physics in India for a

generation or more.

Satyendranath Bose (1894-1974) was the firstto realize the statistical mechanical consequences of

identity in quantum particles (Bose-Einstein

statistics) and applied it to light or photons, thus

inventing quantum statistical mechanics. Meghnad

Saha (1893-1956) showed that the origin of unusual

stellar line spectra is the presence of different ionic

species in stellar matter due to thermal removal of

different numbers of electrons from radiating atoms,

thus clarifying a great mystery in astrophysics andproviding a way of estimating temperatures of stars.

Saha was also active in public life, e.g., science and

economic planning, calendar reform, a stint as

nominated Member of Parliament, and founding

and nurturing an Institute of Nuclear Physics in

Kolkata. K.S.Krishnan (1898-1961) collaborated in

the discovery of the Raman effect, did very precise

measurements of magnetic anisotropy in crystals

and understood the results in terms of crystal fields,

and also proposed a theory for the resistivity ofliquid metals based on the scattering of free

electrons by a dense highly correlated collection of

atoms. The theoretical astrophysicist S.

Chandrasekhar (1910-1995; Nobel Prize, 1963)

started his epic career from India where he had

begun to think at the age of twenty or so about the

maximum mass a stable star can have, the

Chandrasekhar limit; he went on to develop this

and other areas of astrophysics and cosmology on

a monumental basis in England and then USA

where he settled. These physicists worked mostly

at universities, those being the only places for higher

education and research in the pre-Independence

period except for two primarily research

institutions, namely the Indian Association for the

Cultivation of Science, Kolkata, and the Indian

Institute of Science, Bangalore.

In the 1950s, the picture changed in several

ways. The charismatic Prime Minister of inde-

pendent India, Jawaharlal Nehru, believed

strongly in nation building through centralized

planning and government institutions, and in the

essentiality of science both basic and applied for

this. As a result, a large number of state supportedresearch and development laboratories were set

up, for example the cluster associated with the

Council of Scientific and Industrial Research. This

was also the period when big science physics

began to become prominent all over the world

following the release of nuclear energy, and the

atom bomb. The field found a visionary leader in

Homi Bhabha, (1909-1966) an outstanding

theoretical physicist who was also very close toNehru, well known for his work on 'showers' of

electrons and positrons accompanying high

energy cosmic rays as they pass through the

atmosphere. Bhabha conceived and helped set up

a collection of institutions such as the Tata

Institute of Fundamental Research (TIFR, 1945)

and the DAE (incorporated as Atomic Energy

Commission in 1948) which itself had a wide

spectrum of activities ranging from power

reactors to metallurgy of nuclear fuel materials.He inculcated the spirit of self-sufficiency in

instrumentation and technology development.

He also built up people and groups, by choosing

well, giving them the freedom and support

needed, and generating and sustaining a spirit of

great things to be done.

In physics, a number of groups quickly attained

international prominence (in the 1950s and early

1960s) in relatively new fields, e.g., cosmic ray

research, neutron scattering and radio astronomy. In

the field of cosmic rays, D.M. Bose and others from

Kolkata had observed very early (in 1941) cosmic ray

particle tracks in photographic plates exposed in the

Himalaya, and had identified new particles with a

mean mass 200 times that of the electron. This was

six years before Powells systematic development of

the photographic emulsion method, and discovery

of pi mesons in cosmic rays. In TIFR, the cosmic ray



4/9

group used balloon flights carrying nuclear emulsion

stacks to obtain important results on masses and

decay modes of heavy unstable particles (produced

by cosmic rays). This group established itself overthe years as a major group in the study of primary

cosmic radiation, particularly the heavy primary and

high energy electron components. The extensive air

shower array at Ooty was one of the leading facilities

for the exploration of extremely high energy cosmic

rays. The various depths available in the Kolar Gold

Fields (KGF), up to almost 2 miles below the surface

offered one of the few world class places for the study

of extremely energetic cosmic ray mu mesons and

neutrinos. Experiments at KGF were carried out on

an international basis with groups from England and

Japan; the collaborative effort with the Japanese

group lasting over three decades must surely be one

of the longest collaborative scientific efforts in the

world. The KGF work resulted in the most

comprehensive depth-intensity data for muons up

to the greatest depth of 9,600 ft. below the ground.

The first natural (atmospheric) neutrino interactions

were detected in KGF in 1965. The first dedicated

experiment to search for nucleon decay to a life time

of up to 1,031 years was carried out at KGF; this was

the first such detector operational in the 100 ton

category. In neutron scattering, the group at BARC

was one of the early leaders (in the 1960s) in using

inelastic scattering to probe elementary excitationsin condensed matter. The occultation radio telescope

at Ooty, set up in 1970, provided important results

relating to the apparent angular size of galaxies with

their energy flux. The development of optical

telescope facilities also dates to this period; a number

of interesting results such as the discovery of rings

surrounding Uranus, and the measurement of star

clusters in the Large Magellanic Cloud and their

kinematics are from this period.

Somewhat later, a number of small or

laboratory-scale activities, mainly in condensed

matter physics, centered around individuals, began

to bear fruit. Perhaps the best known is the sustained

work on liquid crystals done at Raman Research

Institute in Bangalore; the discovery of a new

arrangement in liquid crystals, the discotic phase with

a stacking of disc like molecules, (in 1978) is perhaps

a high point in the contributions by this group, which


Balloon flights for study of cosmic rays.

(Inset): Bhabha releasing a balloon.

Photos:M.G.K

.Menon


5/9

continues to be one of the leaders in the world in this

field rich in new science and technology. A group in

TIFR has, for more than a generation, made often

pioneering discoveries in the still lively and

fascinating field of rare earth intermetallic

compounds. Their forte is synthesis and experimentalanalysis of anomalous systems in which the generally

completely atomic f electrons (of the rare earth

elements) hybridize with the s andpband electrons, to

produce heavy electron metals and insulators (the

nearly localized electron moves slowly from site to

site), or give rise to novel superconductors with

unlikely ingredients (the rare earth borocarbides). In

the field of quasicrystals, significant early

contributions on different families, on structure, andon systematics of approximants are due largely to the

Indian community of physical metallurgists. This was

in a sense an offshoot of a major programme on

rapidly quenched metals. Interesting studies on

critical phenomena, e.g. breakdown of the rectilinear

diameter law near Tc, and precise measurements of

unusual exponents and critical light scattering near

special critical points in carefully chosen fluid

mixtures, date from this period, and are continuing.

Following the Raman tradition, a number of softmodes in ferroelectrics were studied by optical as well

as neutron scattering methods. High pressure studies

of phases and phase transitions in metals and alloys

have yielded insight into electron phases.

The tradition of atmospheric studies goes to

back to S.K. Mitra at Kolkata in the thirties, and

continued with important work on low frequency

propagation in the ionosphere, aeronomy and the

ozone problem.

We now describe Indian contributions to

theoretical physics from the 1950s till the 1980s. In

the 1950s a programme of selecting and training

physicists, chemists and engineers was started in

Mumbai under the leadership of Bhabha. This

provided the growing atomic energy programmme

with professionals; many research physicists also

started their career here. In addition, many scientists

who did their Ph.D. and subsequent research

abroad returned to India. A number of centres of

quality (universities and research institutes) had

been training professional physicists since the

twenties or so. Because of increased mobility and

ease of communication, international collaboration

as well as working abroad for some time becamecommon. All this, along with a rapid growth in the

number of physics based government supported

institutions after Independence, led to a major

expansion in physics; because of the relative

sparseness of experimental research and the slant

of the intellectual culture, there was (and is) a large

thrust in theoretical physics. We mention below

some contributions in areas such as particle and

nuclear physics, gravitation and cosmology,condensed matter physics and statistical mechanics.

Theoretical particle physics has over the past

half century gone through many stages. To all of

these, Indian physicists have made significant

contributions. Perhaps the best known departure

was the hypothesis in the late fifties (1957) that the

parity violating weak interaction and decay process

is maximally so, arising phenomenologically out of

a fermion current that is of the form (V-A), where V

is a vector and A an axial vector. This (V-A)hypothesis, proposed after analyzing all available

experiments (and inconsistent with a few of them,

which were subsequently shown to be in error), was

a breakthrough towards the present theory of

electro-weak interactions. An early area of

important activity was the formulation of

constraints and sum rules on various elementary

processes, using only general principles in the

absence of a dynamical theory, with important

results on scattering cross sections and amplitudes.

In the phase where algebraic properties of quantum

particle currents were analyzed, exact low energy

theorems were obtained. Gauge field theory,

quantum chromodynamics (QCD) and electro-weak

unification leading to the standard model of

fundamental particle interactions, have all seen

important original contributions, ranging from

results in relevant quantum field theories to



6/9

predictions and analyses of experiments. For

example, it was shown quite early that the quanta

of a massless Yang-Mills (gauge) field are confined

(much before the advent of QCD). Very early, one

loop (higher order) corrections to muon decay were

obtained in gauge theory and shown to be finite. Alepton isolation criterion for the top quark was

proposed as a means of detection, and prediction of

its mass was made. Charged quantum solutions and

charged vortex solutions were shown to be present

in appropriate field theories. Various possible

experimental signatures for detecting the quark

gluon plasma in high energy collisions between

heavy ions have been analyzed, and their

uniqueness discussed. The consequences of the spincontent of nucleons in several nuclear reactions

were examined within the QCD. The detailed nature

and implications of the chiral phase transition in

lattice QCD were determined. Physics beyond the

standard model, namely in supersymmetric models

has been actively explored, both from a formal

viewpoint (e.g. the solution to the naturalness or

gauge hierarchy problem in supersymmetric field

theories, this being a strong theoretical argument

for such theories) and the approach of using highenergy collision events to set limits on say masses

of supersymmetric analogues of quarks, gluons, and

Higgs bosons. Another fruitful area is at the active

interface of cosmology and particle physics ; an

early example is a limit on masses of weakly

interacting particles such as neutrinos, from

cosmological considerations (this was perhaps the

first suggestion of the existence and relevance of

dark matter in the universe).

In theoretical nuclear physics, a great deal of

original work has been done on the microscopic

approach to nuclear structure, especially the shell

model. For example, relating the spectrum of a

particle - particle and a particle - hole configuration,

the magnetic moments of neighbouring nuclei could

be connected, and an estimate obtained for three

body nuclear forces. A method for reducing the

nuclear three body problem to two body problems

for separable potentials was used extensively for

understanding few nucleon systems, and also for

the three quark model for a nucleon. Some of the

conclusions from the latter presage a new degree of

freedom for quarks, now well known as 'colour'.

There is a long tradition of research in generaltheory of relativity and gravitation, earlier mainly

in departments of mathematics. Some of the early

major results are the exact solution of Einstein's

equations for the case of any electrostatic field, and

for a radiating star, as well as the equation which

turned out to be the key ingredient in the proof of

the black hole singularity theorems (Hawking and

Penrose). Other important contributions were made

to gravitation theory and cosmology, such as thedevelopment of steady state cosmology, various

aspects of black hole physics, and the seismology

of the sun based on its normal modes of oscillation.

In the area of condensed matter physics and

statistical mechanics, activity started in the 1960s.

An early result was the recognition that orbital

ordering in Jahn Teller distorted oxides is an order

- disorder transition, rather than displacive. It was

shown that the exact ground state of an

antiferromagnetically coupled spin system (for aparticular ratio between nearest and next nearest

neighbour couplings) is a dimerized superposition

of spin singlets, an important signpost in quantum

magnetism and a forerunner of spin singlet or

resonating valence bond ideas for

antiferromagnetism and high temperature super-

conductivity. A theory of unusual time dependent

specific heat and heat pulse propagation in glassy

dielectrics at low temperatures was developed.

Qualitative and quantitative consequences of

quantum spin fluctuation effects in itinerant electron

(fermion) systems with ferromagnetic transition

temperature T ~ 0 were spelt out ; the related,

presently active field of quantum critical

phenomena developed a generation later. The

theory of liquid to solid transition in (real) dense

classical systems was developed, in terms of a new

free energy functional of the density involving



7/9


known strongly nonlocal fluid phase correlations.

This approach has proved of value in a number of

phenomena in which both the fluid and the solid,

as well as large deformations of the solid are

involved.

Optical nonlinear susceptibilities for semi-conductors and at metal surfaces were predicted

and calculated, as was also the prominent surface

enhanced Raman scattering. The nature of ground

state and excitations in coupled spin chains is a

theme of continued activity. It is a field that has

recently seen a very large amount of experimental

work because of synthesized spin ladder

compounds with unusual properties. Here, exact

solutions for ground states for chains, ladders andspecial two dimensional systems have been

obtained. Multimagnon bound states and solitonic

excitations have been explored. Conservation laws

for and exact integrability of one dimensional lattice

electron systems with interaction have been

discovered. A complete renormalization group

based analysis of the properties of a magnetic

impurity in a metal (Anderson model) as it evolves

from weak to strong coupling with its environment

on cooling was developed. An inverse orbitaldegeneracy expansion was proposed for Anderson

model magnetic impurity systems, in the context of

mixed valence and heavy fermions. The essentiality

of 'hedgehog ' like spin defect textures for the

ferromagnetic - paramagnetic transition in systems

was shown. The long time relaxation behaviour of

disordered ferromagnets was shown to be

dominated by exponentially improbable

ferromagnetic domains. The dependence of the area

of the hysterisis loop in magnets on the size

frequency of the reversing field was analyzed for

the first time and power law relations obtained, the

results being close to those known from the

experiments of Steinmetz more than a century ago.

The above account necessarily touches on a wide

range of phenomena and models, reflecting the

nature of condensed matter physics.

In other areas of theoretical physics, some of

the major contributions are the following. In the

1950s, Pancharatnam, while exploring the

description of the state of polarized light in terms

of a vector with the tip on the surface of a 'Poincare'

sphere, clearly understood and enunciated the idea

of a geometrical phase (Berry phase; now oftencalled the Berry-Pancharatnam phase) associated

with changes of polarizarion described by the tip

executing a closed curve on the Poincare sphere.

Subsequent work includes extension to non-closed

curves, kinematics and mathematical structure of

the theory. In a contribution of central value to

biochemistry and biophysics, Ramachandran and

colleagues showed that dihedral angles between

successive molecular groups in proteins aresterically constrained, and can lie only within

certain regions of values (Ramachandran diagram).

In the area of quantum optics, in addition to the

basic coherent state representation of electro-

magnetic fields, pioneering work has been done in

areas such as cooperative resonance fluorescence,

pair coherent states and squeezing etc.. Plasma

physics is another area with significant Indian

contributions, e.g. the theory of parametric

instabilities and stabilization of tokamakballooning modes.

The survey is concluded by mentioning some

physics research facilities and achievements pertaining

to the last decade or so. The attempted description will

be grossly incomplete and patchy, since the physics

community is rather large, with perhaps 5,000 or more

Ph.D. physicists. Most major areas of physics are

pursued, so that there is a large and widespread

knowledge and research base. This base is formed by

the sustained efforts of a large number of dedicated

practitioners working under difficult conditions, and

a relatively small number of prominent figures or

leaders, some of whom have made contributions of

major significance to physics. Afew individuals have

successfully built and/or nurtured major institutions

and facilities, especially in government departments

connected with atomic energy, space, defence etc. A

culture of self-reliance of developing the tools needed,


8/9

and of applied science at a high level of competence

in diverse areas, has been developed. In experimental

physics research, a few fields stand out in terms of the

investments made, and facilities created. These are

overwhelmingly in the area of 'big' science. In the field

of astronomy and astrophysics (as described in theChapter on this area) a number of major facilities have

been set up that are of world class and available widely

to scientists within India as well as from abroad. A

number of medium energy particle accelerators have

been functioning in the country, e.g. a heavy ion

accelerator in the Nuclear Science Centre, Delhi, used

as a common facility in Nuclear Physics and Materials

Science for all Indian universities for about a decade.

A major tokamak facility using a solid statesuperconducting magnet is coming up at the Institute

of Plasma Research, Ahmedabad. An ultraviolet

synchrotron is operational at the Centre for Advanced

Technology, Indore, and an X-ray synchrotron is

expected to come on line soon.

There have been many interesting

developments in experimental condensed

matter/materials physics. The energy dependence

of the electronic excitation spectrum near the T=0

metal insulator transition, with the possibledevelopment of a pseudogap, has been explored.

While subsequent to the discovery of

superconductivity in the cuprates, considerable

amount of materials related work was done, the

absence of quality single crystal growth and

cryogenic facilities has proved a serious handicap in

this as well as other areas. However, novel

phenomena associated with flux lattice melting,

plastic flow of the flux lattice etc. have been

discovered (TIFR) using cuprate and other

superconductor crystals grown elsewhere. The

nature of atom (or molecule) light interaction in

intense laser fields has been actively probed. Aspects

of electronic and optical processes in quantum well

semiconductor structures have been studied by

several groups. An interesting new development in

a field of basic interest as well as current activity is

the detection and quantitative analysis of electrical

noise near the metal insulator transition in silicon

(universal conductance fluctuation), its suppression

by electric fields and thermal dephasing. Very careful

structural work on quantum and mixed

ferroelectrics has greatly clarified the nature of

phases in these; the phenomena and materials are ofimportance both scientifically and technologically.

In the growing field of colossal magnetoresistance

oxides (manganites) a large amount of well known

work exploring the bewildering variety of electron

driven phases and phase transitions has been done

(mainly at IISc). Two notable features of this body of

work are the fruitful collaboration between solid

state chemists and physicists, and the systematic

study of phenomena using several probes, e.g.transport, tunnelling, heat capacity, light scattering

and EPR. Fullerenes (C60, C70....) and carbon

nanotubes are another aspect of this kind of work.

For example, in Y junctions of carbon nanotubes,

rectification has been shown to occur; many unusual

properties of single and multiwalled nanotubes are

coming to light. We have here entered the completely

quantum world of nanoscience where there are no

boundaries between different areas of science, and

between science and technology. However, facilitiesfor sustained frontier work in this area are very poor.

A growing concern in modern physical science is the

study of soft systems, such as colloids, membranes,

foams, and gels, in which the energies associated

with the relevant degrees of freedom are of low

energy (~ kB T). Here, in addition to liquid crystals

mentioned above, aggregates of colloids forming a

glassy phase have been studied structurally (and

kinetically), diffusion of photons in this medium has

been analyzed, and surfactant based self-organized

assemblies have been probed using light scattering.

In theoretical physics, the last decade has seen

a wide range of contributions. In string theory, an

area of great intellectual ferment, the Indian

presence is quite prominent. While many of the

developments over the decade had active Indian

participation, at least two stand out because of the

critical Indian contributions namely the idea of



9/9

duality between strongly and weakly interacting

string field theory, a major breakthrough in the field

with wide implications and an absolute value for

black hole entropy from a quantum model for it.

Contributions to theoretical astrophysics range

from an analysis of shock wave induced triggeringof starburst collections in interacting galaxies and

a calculation of the selfconsistent (gravitational)

potential at the core of elliptical galaxies to early

discussions of gravitational lensing as well as

nonlinear mechanisms for large scale structure

formation in the early universe.

Indian theorists have contributed notably to

ideas connected with high temperature super-

conductivity, e.g. the resonating valence bond modelfor antiferromagnetically coupled electron spins on

a lattice and the associated gauge degree of freedom

which are believed by many to be crucial ingredients

in any theory. A long range one dimensional

antiferromagnetic interaction model with exactly

known ground state, and with spinons was

discovered a little more than a decade ago. The

nature of interlayer tunnelling and consequences for

the puzzling anisotropy of resistivity in the cuprates

has been discussed. Avery interesting proposal fora mirrorless laser in a disordered one-dimensional

medium using (Anderson) localization properties

has been made. Anumber of interesting contributions

to mesoscopic physics, e.g. conductance fluctuations

and persistent currents in mesoscopic structures,

have been made. In the area of strongly correlated

electron systems, the dynamical mean field theory

has been extended in several significant ways, in

particular going beyond the single site

approximation to describe clusters. In what has now

become a standard method in the field, it has been

shown how photoemission data can be used to

derive reliable and precise information about electron

spectral density in cuprate superconductors.

In statistical mechanics, a unique exactly

soluble model for self-organized criticality, the

Abelian sandpile model, was formulated and the

results analyzed. A number of interesting soluble

models in low dimensions for interfacial dynamics

were proposed and solved in the broad area of

nonequilibrium statistical mechanics. Multiscaling

behaviour in turbulence has been numerically

explored. Chaotic control of cardiac arrhythmia is

one of the many fascinating contributions toemerge from the increased attention given to

nonlinear dynamics and chaos. Some others are

chaotic computing, yielding of solids and

premonitory phenomena in earthquakes. The

nature of glassy free energy minima and their

landscape, and a formal approach to freezing in

disordered systems, are some efforts at

understanding one of the major unsolved problems

in condensed matter physics, namely the glasstransition. In the area of equilibrium statistical

mechanics, phase transitions in polymeric systems,

the nature of the DNA denaturation / unzipping

transition, and flux lattice melting are some of the

notable efforts. Original work on autocatalytic

networks as involved in prebiotic evolution has

been carried out. Work on spin ice, namely dipolar

interacting spin models with residual entropy

(measured in some pyrochlores) as in some models

of ice, has attracted attention.The above incomplete survey suggests that

physics activity in India continues at a high

international level and over a widening range. While

this is broadly true, there are a number of clear signs

suggesting that immediate corrective action is

necessary for the continued vitality, growth and

usefulness of not only physics but science in general.

These signs are briefly: (a) the generally poor state of

experimental science (at least physical science) in India,

due to continued lack of support for laboratory-scale

physical science (by a factor of five or more), (b)

relative paucity of physics related (high) technology,

(c) the concentration of research in a small number of

non-teaching institutions with few students, and the

blighting of universities with many students, an

inherently unstable arrangement not found in

scientifically vigorous societies, and (d) a sharp decline

in the number of students taking up physics.


Physics_scence and India

Documents

Transcript of Physics_scence and India