Ideas and Researches on Physical Concepts in India*

Ideas and Researches on Physical Concepts in India*

A K Bag**

(Received 01 May 2015)

Abstract

The ideas on physical concepts in India have changed through the centuries initiated first byguru-śiya paramparā (teacher- student relationship), and later extended further based on varieties ofquests & experiments. The Vedic & Upaniadic schools (c.6500 BC - 500 BC) first expressed anguish asto how the universe was created by Gods, later on giving importance to nature, natural order and thecosmic creation. The Buddhist, Jain, Sāmkhya & Nyāyavaiśeika schools (c.501 BC - 1000 AD) gavecentral focus to Nature (prakti), in place of Gods, as a limitless entity which is self-existent. The Sāmkhyarecognized five elements in nature: kiti (earth), āpa (water), tejas (fire), vāyu (air) and ākāśa (space)both at the atomic (paramāu) and molecular (au) level with guas [sattva, rajas, tamas] as attributesexisting in equilibrium. Emphasis on duality concept (purua and prakti, śiva and śakti, hara and pārvati,mercury and sulfur) by the Tantrik and Alchemical traditions was held responsible for equilibrium state.The metaphysical explanation of how the sthula-bhūta paramāus like solid, liquid,, gases, heat & light,ether etc are constituted based on tanmātrās (physical energies represented by sound, touch, colour, tasteand smell) together with likeness, cause and effect relationship of the combination of the atoms is alsoexplained. The Greek and Islamic thoughts during the period (c.1001-1800) accepted also similar atomicconcepts of matter which are no better than those of the Indians. The European knowledge in physicalscience in the Colonial phase in India (1801-1900) opened up after great initial reluctance, and theknowledge of great stalwarts like, Copernicus (on heliocentric theory), Kepler (elliptical path of planets& planetary laws), Huygens (polarization of light), Newton ( motion of body in Cartesian and Polar co-ordinates, periodic motion, law of universal gravitation, sound and its propagation, light), Galileo(telescopic observation of heavenly bodies), Oersted, Faraday & Maxwell (magnetic properties of materials,electricity, charge), Kirchhoff & Planck (radiation), Mendeleyev (periodic table) and others, infiltratedthrough the local initiatives influencing Indian minds. These helped to establish a Golden phase of sciencein India (1901-1960) with J C Bose, C V Raman, Meghnad Saha, Satyendranath Bose, S K Mitra, H JBhabha, S Chandrasekhar and others extending the knowledge in diversified field of physical science.The work was of great order, some of which brought great international fame in global perspectives. Thephase (1961–2000) was indeed a period of consolidation in India which led continued emphasis oncosmic ray research, atmospheric studies, search for sub-atomic elementary particles in the formation ofbuilding blocks of the universe, classification of forces and of elementary particles imparting importanceto Model of Expanding universe with radiation against the Steady state of Big-Bang Model. The observerand observed have however created many a dilemma in present ideas and thoughts in establishing anorder between the physical and biological world.

Key words: Bhabha scattering, Big – Bang model, Black hole, Boson, Buddhist schools, Diodedetector, European knowledge, Cosmic evolution of matter, C V Raman, Electro-magnetic spectrum,Elementary particles, Golden phase of science in India, Greek schools, H J Bhabha, Ionization theory,Islamic schools, Jaina schools, Laws of gravitation, J C Bose, M N Saha, Nyāya-Vaiśeika school, Motionof bodies, Nuclear program, Origin of Universe, Periodic table, Physical concepts, Quantum mechanics,Raman effect, Response in plants, Sāmkhya school, S Chandrasekhar, S N Bose, S K Mitra, Spectroscopicobservation, Expanding universe & Steady state models, Telescopic observation, Upper atmosphere.

*Co-published with Indian Science Congress Association (ISCA).**Editor, Indian Journal of History of Science, INSA, New Delhi; Email: [email protected]

Indian Journal of History of Science, 50.3 (2015) 361-409 DOI: 10.16943/ijhs/2015/v50i4/48312

362 INDIAN JOURNAL OF HISTORY OF SCIENCE

1. INTRODUCTION

India in its more than six thousand years’history has produced many great theoreticians andpractitioners of arts and science. The physicalconcepts are generally recognized as theknowledge or perception about origin of universeincluding knowledge of its evolution, structure,motion, and properties of body or substance orenergy, how they are related, and how the ideas inthese concepts have changed through thecenturies. The subject, though appear to soundvast, bold and imaginative, there are practicallyno specialized texts in the early Indian traditionsexcept in the later periods which exclusively dealwith them. Each school of thoughts has developedits own physical and metaphysical views. Toappreciate the subject, I have discussed theevolution of these concepts in phases.

2. VEDIC & UPANIS. ADIC SCHOOLS

(C. 6500 BC–500 BC)The Vedic schools of Sahitās,

Brāhmaas, Ārayakas, Upaniads and of theVedāgas flourished during this period c. 6500BC–500 BC. The antiquity of this prehistoricphase is based on astronomical facts verified bymany recent sky-maps (Bag, 2015, pp.3-12, 21-22). The gveda is the earliest of the four Sahitās(g, Sām, Yajur and Atharva) which, in its well-known hymns (RV.X.129.6-7), speaks with wonderabout the creation of the universe1. The Englishtranslation of the verse (Wendy, 1981, pp.25-26;also quoted in Lahiri, 2013, p.142) runs thus,

‘Who knows, who ever told, from whencethis vast creation rose?

No gods had then been born—who thene’er the truth disclose?

Whence sprang this world, and whetherframed by hand devine or no –

Its Lord in heaven alone can tell, if evenhe can show’.

The gvedic sukta (RV.X, 90) has alsosixteen mantras which provided the story ofcreation giving it a highly philosophicalorientation, and indeed constitute a most difficultand complex thought to appreciate. In short, itconceived an idea of a purua (Cosmic Being);the derivative, ‘pu’ meaning purity, purua is onewho is pure and untouched. In Brāhmanic andUpaniadic literature, the personification of‘Supreme Being’ has profound influence, and inmajor Upaniads, purua has been emphasized as‘inner consciousness’, the essence of man, theātman. This type of metaphysical discussion is alsofollowed in Sāmkhya and Vedānta. A few otherconcepts in the period merit attention:

The concept of universe of the Rgvedicpeople was equally interesting. They first madean effort to develop this concept to establish anorder between the outer world and the inner urgeof human spirit. The Fire (agni), as representativeof the Sun in the heaven, was conceived as a greatwell-wisher, wealth-giver, illuminator andassociated him with his own activities throughworships and sacrifices. The gveda describespthivī (earth), antarika (sky, literary meaning‘the region between the earth and the stars’), anddiv or dyaus (heaven), as parts of his ‘universe’(RV.I.115.1; II.40.4). It has even been tried toestimate the distance of the heaven from the earth,of course the values being estimated as ‘ten timesof the extent of the earth ‘(RV.I.52.11); ‘ a thousanddays’ journey for the sun-bird’ (AV.X.8.18);‘thousand days’ journey for a horse’ (Ait.Br.II.17.8); and so on. All these of course arefigurative expressions indicating that the extentof the universe is somewhat infinite. The threeprimary altars—Gārhapatya (circular), Āhavanīya(square) and Dakiā-vedi (hemi-spherical or

1ko andhā veda ka iha pravocatkuta ājātā kuta iyam visi / arhāgdevā asya visarjanenāthā ko veda yata āvabhūva // iyamvisiryata āvabhūva yadi vā dadhe yadi vā na / yo asyādhyaka parame vyomant so anga veda yadi vā na veda // (RV.X.129.6-7)

IDEAS AND RESEARCHES ON PHYSICAL CONCEPTS IN INDIA 363

semi-circular), on which the house-holder placedtheir fires (agnis) for daily sacrifice, representingearth, heaven and antarika respectively had sameground areas. The shapes of the altars were sodesigned, for it appeared to them the earth asspherical, heaven as cube (used to indicate fourcardinal directions—east, west, north & south),and antarika as hemispherical. The same areasuggests that they conceived it as obligatory toestablish a coordination among these three entities.The perception of three gods— Agni in earth,Indra (or Vāyu) in aerial region (antarika), andSavit (Sun) in the heaven in the niruktas appearsto be quite interesting. They had a feeling that Agniis protected by Sun and Indra, and all three werealways given a prominent place in the worship.

tam, a cosmic order or a law, whichguides the course of things, is also formalized inthe gveda (RV.IV.40.5). Winternitz in his Historyof Indian Literature (Vol.1, 1927, p.154) used itin the sense of the ‘order of the universe’. Keithin his Religion and Philosophy of the Veda andUpanishads (Indian reprint, 1970, pp. 83,248) saysthat tam means ‘cosmic order’ as well as ‘moralorder’. Or in other words, he clarifies that it is the‘primal principle’ which not only guides humanactivities for his sat and asat karmas, but alsodecides purpose of Sun, his all-pervading lightsand other external objects, and even the flow ofthe streams (RV.VI.2). Gods are often describedin the Vedas as ‘Guardians of tam’, for gods likeMitra and Varua are often invited by the Vedicpeople to increase the size of yajas and preserveit by following the path of truth (RV.I.23.5). Theapparent movements of sun and moon as seen fromthe earth is likewise comes under this law.However, Vedic schools are silent as far as theconcept of time is concerned, as to when and howthe movements of these heavenly bodies began.gveda only says, ‘āditya lights up and createsenergy’, and the ‘appearances of Uas’ and‘illumination of the universe’ are in conformitywith tam (RV.III.61.7).

The famous Nāsadīya sūkta of the gveda(RV.X.129) first conceived primeval water as thefirst element, and associated it with the process ofcreation. Later on, the Bhadārayaka Upaniad(Bh.Up.V.5) speculated, ‘In the beginning, thisworld was just water’. Chāndogya Upaniad(Chand. Up. VII. 10) says,‘ It (world-stuff) is justwater solidified, that the earth... the atmosphere....the sky.... the gods and men... beasts and birds...grass and trees... animals together with worms...flies and ants, all these are just water solidified’.It also accepted the three elements, water, fire andākāśa as the basis for understanding of brahmaas the universal soul. The idea of five elements isalso found in the Maitri Upaniad (Mait.Up. III.1& 2; VI.4). The philosophical conception of fiveelements has found elaborate extension in theSāmkhya school discussed in the next section.

3. BUDDHIST, JAIN, SA–MKHYA

& NYA–YAVAIśES. IKA SCHOOLS

(C. 501 BC–1000 AD)The period is synchronized with the rise

of Buddha (b. 563 BC) and Buddhism, Mahāvīra(contemporary of Buddha) and Jainism, and theextent of influence and vast amount of literatureproduced by their followers in India. Sixphilosophical schools (Sadarśanas), the epics—Rāmāyana & Mahābhārata, the schools ofAyurveda (medicine) and Jyotia (Siddhānticastronomy) came out with many basic knowledgeabout the universe. Buddhist notion of another lifeor life after death (parajanma) and attainment ofnirvāna (free from the life cycle for good work)have made the concept of time as continuous andinfinite. The introduction of Yuga as time unitconsisting of Kta (Golden Age of 1,728,000 solaryears), Tretā (Silver Age of 1,296,000 solar years),Dvāpara (864,000 solar years), and Kali (Iron Ageof 432,000 solar years) maintaining a ratio 4:3:2:1had a considerable effect on the epics, purāas aswell in astronomical texts. The concept of space,direction and time also got concretized with the


recognition of the planets, viz., mercury (budha),venus (śukra), sun (sūrya), mars (magala), jupiter(bhaspati), saturn (śani) lying in the sameconcentric plane, and their revolution with uniformcircular motion round the earth (geometricconcept). All astronomical texts have a section(Tripraśnādhikāra) dealing with dik (direction),deśa (position), and kāla (time) with methodologyhow to find them for a particular position ofcelestial bodies. Local time was considered as afunction of sun’s shadow-length and measured bya śanku (pole of height 12 agulas or roughly 9inches) from sun’s position at different latitudesof the earth.

The Buddhist metaphysical tenets alsohave avoided God as a creator, rather it developedthe postulates that the universe is self-existent,having no beginning in time, rather limitless inboth directions, past and present. Buddhistinfluence in Central and South Asia, Alexander’sinvasion, trades and cultural contacts created asituation ( though in a restricted manner becauseof the various barriers including language), whichwas fit for free thinking and exchange ofknowledge with scholars in India and outsideworld.

Every age has its own science, beset withnew issues, problems and solutions. The spirit ofenquiry and skepticism which characterized thegrowth of Buddhism favored the development ofscience. New thoughts could be found in theteaching of philosophical schools of Sāmkhyas,Nyāya, and Vaiśeikas. The Buddhist Vihārascontinued to be centres of learning. So is Jainaand other schools which followed materialistictraditions and believed in the sense perception asa valid source of knowledge as well as the basisfor the reality of natural law. Frits Staal, a well-known historian of science, in his lecture on‘Concept of Science in Europe and Asia’ at theInstitute of International Institute for Asian Studiesin 1993 says, ‘My impression is that Indianscientific tradition is as rich as the Chinese, an

impression confirmed by Needham’s work, whichdoes not only deal with China but abounds inreferences to western (including Islamic) andIndian sciences’. According to him, ‘Pāinideveloped Sanskrit grammar as derivationalsystem in some respects more sophisticated thanthe deductive system of Euclid’, and furtheremphasized, ‘India is richer than China in abstractand theoretical sciences such as mathematics andlogic’. The philosophical schools of this periodaccepted atom as the basic unit and gave a logicalstructure which attained a unique place.

The Sāmkhya school extended theUpaniadic idea of the concept of element toatomic and molecular level. Prakti, according toSāmkhya view of cosmogenesis, is formless,limitless, ubiquitous, undifferentiated, indestructi-ble, indeterminate, and incomprehensible infinitecontinuum without beginning and without end, inwhich and out of which the un-manifested anddifferentiated cosmic universe has been evolvedthrough successive stages (Ray, 1966 pp.1-3). Itis also an amalgam of three guas existing inequilibrium. These are: sattva (essence ofintelligence staff), rajas (energy) and tamas (mass-stuff or inertia), which according to Seal (1915),are diverse moments with diverse tendenciesinherent in Prakti. The successive stages ofcosmic evolution of matter according to Sāmkhya-Pātanjala system ( Vyāsa-bhāya, sūtra 2, pada2) as described by Seal (1915), Ray (1956 &1966), Subbarayappa (1966) and others, may besummed up as follows:

Prakti evolves → Mahat (cosmic matter,or stuff of consciousness);

Mahat → Ahamkāra (ego, both objectiveand subjective);

Ahamkāra → Tāmasik-ahankāra(objective modification) + Rājasik-ahamkāra (subjective modification);

Tāmasik-ahamkāra → Sūka-bhūta-tanmātra (subtle material potencies ormatter-stuff) → Sthūla-bhūta-paramāu


(atomic and molecular constituents ofgross matter) → finally, Dravya(individual substances composed ofatoms and molecules);

Rājasik-ahamkāra → Asmitā (empiricalego) → Manas and Indriyas (Mind-stuff,sensory and motor stuff).

This theoretical frame-work shows thecosmic evolution of both matter-stuff and mind-stuff. Bhutādi has been conceived as matter in thesuprā-subtle state which is absolutelyhomogeneous and inert, without any chemical orphysical property excepting that of quantum ormass. Tanmātras likewise was viewed as infra-atomic particles of matter which possesses specificpotential energies represented by sound, touch,colour, taste and smell. The śabda-tanmātra(sound) has the physical energy of vibration(parispanda); the sparśa-tanmātra (touch) has thephysical energies of impact besides that ofvibration; rūpa-tanmātra (colour) has the energyof radiant heat and light beside those of impactand vibration; rasa-tanmātra (taste) the energy ofviscous attraction together with heat, impact andvibration; and gandha-tanmātra (smell) the energyof cohesive attraction together with those ofviscous attraction, heat, impact and vibration.From tanmātras arise the sthūla-bhūta-paramāus—ākāśa (mono-), vāyu (dvi-), teja(tri-), ap (tetra-), and kiti (penta tanmātrik) atoms.Then these atomic bhūtas gives rise to fivedifferent types of substances—kiti atoms givesolid, ap atoms liquids, vāyu atoms gases, tejasatoms heat and light, and ākāśa atoms ether.Different properties of different substances areresponsible from the difference in tanmātrikcompositions and collation in their atoms. InSāmkhya view, ākāśa is conceived in two foldaspects, viz., non-atomic ākāśa (kāraākāśa) andatomic ākāśa (kāryākāśa) related to each other ascause and effect. The atomic ākāśa is charged withvibration potential residing in a non-atomic ākāśa,known as space (avakāśa), and serves as a buildingstone of all other material atoms. The Tantrik cult

and the Alchemical traditions developed a dualityconcept like purua and prakti, śiva and śakti,hara and pārvatī, mercury and sulfur to neutralizeor contain the two opposite forces, and consideredthem as inherent part of natural process. Thisconcept is comparable with Dirac’s hypothesis of‘anti-matter’, which fills the space and from whichthe matter is continuously created. The conceptof non-atomic ākāśa as a starting point of materialcreation reminds one of Fred Hoyle’s theory ofmaterial creation.

The Nyāya-Vaiśeika school of Indianphilosophy have also propounded atomic conceptsand allied properties (paramāu-vāda). Kaāda,the founder of Vaiśeika school, developed in hisKaāda-sūtra a system which recognized fourtypes of atoms—kiti, āpa, tejas and vāyu, hasmany points in common with that of Greekphilosopher Democritus (4th century BC). It issomewhat different from the Sāmkhya systemwhich recommended five including ākāśa atom.According to Kaāda, ākāśa has no atomicstructure, serving merely as an inert and ubiquitoussubstratum of sound, which is supposed to travelin the form of waves in the manifesting mediumof vāyu. Kaāda’s view about the propagation ofsound, though purely speculative, is surprisinglysimilar to that of modern science. ThePraśastapāda-bhāya, which is an exposition ofKaāda-sūtra, and Nyāya-kandalī, described atomas a logical necessity and added epistemologicalsignificance. According to Vaiśeikas, atoms areeternal, part-less, spherical, and the gross worldis formed out of atoms. They also believed in fourdistinct types of atoms corresponding to foursubstances viz. prthvī (earth), ap (water), tejas(fire) and vāyu (air). Each type has some specificqualities, which sometimes change with theinfluence of heat (pilupāka). As regardscombination of atoms to formation of gross bodies,the Vaiśeika theory prescribes as follows:

Two atoms—one dyad (dvyauka);Three atoms—one triad (tryauka);


One atom combines with another atomunder an inherent impulse to form a binarymolecule of two atoms (dvyauka). The atomspossess an intrinsic vibratory or rotatory motion(parispanda). Atoms of same bhūta class will unitein pairs and give rise to molecules. Thehomogeneous qualities of binary molecules isretained corresponding to the original quality ofthe atoms, provided that no chemical changes takeplace under the heat corpuscles. The binarymolecules then combine among themselves bygroups of three (triad or trasareu or trui, whichis visible in sunbeam), four, five and so on to formlarger agreegates. The Nyāya Vaiśeika schoolassumed that the combination of two atoms isperformed by invisible force (ada—not visible).However, it was suggested by later commentators(Nyāyavārtika-tātparyaīkā of Vācaspati Miśra,III, 1. 28) that two atoms of pthvī combine underthe influence of a different atom say, atoms of tejor ap. Two unlike atoms e.g., one atom of earthand one atom of water cannot under anycircumstances combine to produce a dyad. Sincedyads form the basis for all triads. The Vaiśeikasystem argues that the structural arrangement ofdyads (vyūha) determine the specific character ofgross substances.. Atoms are neither created nordestroyed, and are therefore permanent. They arespherical, occupying definite positions insidematter. When matter is destroyed it breaks up intoatoms. Atoms and molecules are always vibratingand rotating, and all work and movement can beultimately traced to the motion of atoms.

Kaāda also recognized light and heat asonly different forms of one and the same essentialentity, tejas (radiant energy). He held the view thatsound travels in the manifesting medium of vāyu(air) in the substratum of ākāśa (space). In Nyāya-Vaiśeika system, the transmission of sound wasexplained by the motion of waves, while in Greeksystem it was explained by the particles of soundradiating in all directions in straight lines with asort of conical dispersion (Latham, pp.146-47).

The Indian philosophers also observed theproperties of reflection and refraction of light, andof rarefaction and condensation of air particlesduring the propagation of sound [Nyāyabhāya,(III. 47. 1) of Vātsāyana; vide also the commentaryof Udyotkara (2nd century AD); propagation ofsound has been discussed by Bhatrihari in hisVākyapadīya (Mimāmsā)]. An elaborate accountof various types of motion (gamana), rectilinearand curvilinear (vibratory or rotatory), momentumor impressed motion (vega or samskāra), gravity(motion of a falling body), motion due to magneticattraction, motion due to contact etc is found inthe Nyāya Vaiśeika Praśastapāda-bhāya (3-4th

century AD). Even the attraction of a straw byamber (electrical attraction) has not escaped thenotice of the scholars of Nyāya Vaiśeika. Theancient Indians do not believe in the theory ofvacuum as in the Greeks. They say that when anatmospheric content of a glass jar is exhausted,what remains is not vacuum, but ākāśa or vyoman.It recognized ākāśa as an element which goes asa constituent into the composition of every object.

The Buddhist schools had also batted foratomic concept having subtle differences from thatof Kaāda, and recognized four atoms— vāyu,tejas, ap and kiti. Four essential properties—extension (with hardness), cohesion (withfluidity), heat and pressure (with motion), alongwith four subtle sensible of colour, taste, smelland touch were also accepted. So, vāyu atoms aretouch-sensible having impact or pressure as thecharacteristic property, tejas atoms are colour- andtouch- sensible having heat property, ap atoms aretaste-, colour- and touch- sensible with viscosityas the property, and kiti atoms are smell-, taste-,colour-, and touch- sensible with dryness orroughness as the property. The four elements(bhūtas) formed out of these atoms combine toform aggregates and give rise to organic andinorganic substances. According to Sarvāstivādinschool, a material atom is composed of sevencharacteristic atoms, viz., solid (earth), liquid


(water), heat (fire), moving (air), colour, taste andodor with sense of touch. How a material objectis composed of characteristic atoms is not clear.The later work says that the seven characteristicatoms are set with their apices and centre, and forman octahedron.

The Jaina schools, in general, alsoaccepted the atomic theory and based it on theconcept of pudgala which acts as the vehicle ofenergy in the form of motion. Pudgala, accordingto them, can exist in two forms, as au (atom) andskandha (aggregates or molecule), the latter beingformed from the former. An au has no parts, nobeginning, middle or end, and therefore it is aninfinitesimal, eternal and ultimate particle ofmatter. A skandha has many forms, diad(dvyāuka), triad (tryauka), or an infinitum(anantāūka). A skanda (aggregate) is thereforemade of large number of aus of first, second, thirdorder and so on. An atom possesses an infra-sensible or potential taste, smell and colour, andtwo infra-sensible tactile qualities— roughness orsmoothness, dryness or moistness, hardness orsoftness, heaviness or lightness, heat or cold. Askandha, however, possesses in addition thephysical characteristics of sound, atomic linking,dimension, shape and configuration, divisibility,opacity, radiant heat and light. For chemicalcombination between two atoms, they must beunlike in character, being endowed with oppositequalities meaning roughness and smoothness, ordryness and moistness. The atomic linkingbetween two atoms is also important in thiscontext, for it says that linking will not occur orwill be very weak, if the opposite qualities(strength or intensity) be very feeble. The particlesof like character or similar qualities will notgenerally unite if they are of equal intensity. Thestrength and intensity of qualities, although alike,two atoms may differ widely in character. Evenatoms of similar qualities may enter into chemicalcombination. As a result of linking or chemicalcombination, the properties of atoms suffer a

change. A detaled description of the atomic theoryand theory of chemical combination is found inthe Tattvārthadhigama-sūtra (Chap. 5) ofUmāsvātī (2nd century AD).

The chemical change and heat had beenclosely associated in the Nyāya-Vaiśeika system.Vātsyāyana (first century AD) also says thatchemical changes may occur either by externalheat or may result from the operation of theinternal heat ( Vātsyāyana-bhāya, IV.1.47). Theheat evolved which has undergone changes bycombination is believed to exist in a latent formin the fuel for combination. Udayana in hisKiraāvalī (comm on the Praśaspada-bhāya ofNyāyasūtra) considers solar heat as the ultimatesource of all heat required for chemical changes.This invisible heat was also believed to beresponsible for the change of colour in the grass,for the ripening of mangoes including its changein colour, smell and taste, for conversion of foodinto blood and so on (Nyāyabodhinī commentaryon Annambhatta’s Tarkasamgraha, 8th centuryAD). Heat and light rays were also thought to beconsisting of small particles radiating in straightlines in all directions with high velocity forminga somewhat conical dispersion. On striking theatom they may break the up their groupings, andtransform as per their physical and chemicalcharacter (Nyāyamanjarī of Jayadatta, eleventhcentury AD).

Greek schools, like Indianmetaphysicians, gave the impression that basicelements (or stuffs) were four, and they areresponsible for making all substances in theuniverse – earth, water, air, and fire. However, thespace as a medium of energy was not includedlike that of the Indians in their scheme. Aristotle(384–322 BC) assigned the properties : Earth ascold & dry, Water as cold & moist, Air as hot &moist, and Fire as hot & dry, and said thateverything on Earth was made of combination ofthese elements and all changes other than motiontake place on the alteration of these proportions


(Taylor, 1964, p.17). The whole concept is basedon daily experience. In Greek atomism, atoms andvoid constitute the universe, and the atoms are inperpetual motion. All physical phenomena havebeen explained by the use of both atom and voidand developed on the basis of mechanical way ofthinking. The Nyāya Vaiśeika atomism hasexplained a few phenomena from the atomic pointof view, and various others by means of ada(invisible force), wave motions and so on. Indianatomism is not completely built on a mechanicalway, rather characterized by the atomism of sensewhich explains epistemology of sensation in thehuman body. Science in both these regions hadunique achievements in isolated manner but hadno connection with any experiments or socialneeds. The novelty in atomic concept of mattercould not sustain and develop further because ofvarieties of pressures resulting from classesbetween higher-caste- minority and lower-class-majority, and also attack from foreign power inspite of brilliant metaphysical ideas.

4. SULTANATE AND MUGHAL PERIODS

(C. 1001–1800)This period under the Sultanate and

Mughal rulers in India were mostly busy inmundane affairs. The study of physical aspects ofmatter had almost no patronization, as a result,the interest weakened further. As to academiccontacts between India and the Islamic world,Gāzāli (1058-1111), the well known Islamichistorian of Central Asia, in his al-Munqidh minal-dalā says that out of four types of Islamicthoughts, viz., bātiniyya (Ismālīyya movement),mutakallimūn (followers of atomic concepts),falāsifā (rationalists and scientists), and suffiyyā(eclectic and esoteric trends), the first had notmuch influence on India and went undergroundduring the Sultanate period. The last three groupshad of course no clash with the Indian rulers andintellectuals. Islamic Caliphate in central Asiawhich expanded their area of influence from Spain

in the west, through middle-east to Turkistan, Iran,up to the border of China came closer to India.The area of Islamic science also grew. To cite afew examples, the astronomical works ofĀryabhaa, Brahmagupta, Ptolemy, and of Platoand Democritus were translated into Arabic byBaghdad scholars. Al-Khwārizmī (c. 850)translated Indian works on arithmetic and algebra.The central Asian scholar al-Kindi (c. 800-873)of Basra (Baghdad) had interest on physicalconcepts and wrote on the refraction of light. Al-Hazen (965-1038), a century later, also focussedhis attention on reflection & refraction of light onspherical and paraboidal mirrors and themagnification by lenses. Al-Bīrūnī (973-1048)who came to India, stayed here for about fourteenyears and spent his time in collecting informationon Indian mathematics, astronomy etc anddetermined the specific gravities of number ofmetals and precious stones by the method ofArchimedes. Ibn Sīnā (980-1077), a cotemporaryof al-Bīrūnī and a well-known medical practitionerhad all pervading interest in philosophy,mathematics, metaphysics and sufism, learnt bothIndian methods of calculations (Hisāb al-Hindi)and Euclidean geometry, used mathematicalprinciples in all his explanations creating lot ofconfusion among Indian scholars. His DānishNāma-I’Ālā’l, an encyclopaedia of Islām inPersian discussed on the question of matter andcreation. In fact, Islamic sciences reached Indiaand Europe through Ibn Sīnā’s writings. Ibn Sīnābelieved in the Qurānic doctrine and accepted Godas a creator. He however believed in the theory ofcontinuous creation and atomic concept of matter.His argument was that even the minutest portionof matter could be divided into two. The divisionmay not be possible physically or in practice, butin imagination it can always be done, as is donein mathematics. To cite an example he says,’ ifwe take a small number, its half can also beimagined and the nature of existence of dividedand undivided numbers remain the same. Hedemonstrated that between any two jawhars


(atoms) another jawhar can also be inserted, andjawhar can also be subdivided. With this analogyhe says, ‘it is impossible for a straight line tointersect another straight line at more than onepoint’. Though the analogy is wrong, he succeededin demolishing the atomic concept of matter to agreat extent. Al-Hazen had the idea that theincident and reflected rays of light make equalangles with the reflecting surface, and hisinterpretation regarding relation between theposition of the source of light and its image formedby a lens is known as al-Hazen’s problem. He hadpossibly some fair idea how to make mirrors andlenses and how these could be used to adjust theconvergence or divergence of beams of light andbring its rays to a focus during war withopposition. On act of vision he also said, ‘We seesomething from the seen object passing into theeye’. Spain, specially Cordoba and Toledo,became active academic centres which compiledimportant Indian and other sources under theencouragement of Califs— Abdar-Rahman and al-Hakam II and others, became an active centre forArabic ideas and learning. Islamic scienceflourished but perished within a short time.However, during the sixteenth and seventeenthcenturies, European glassware started coming toIndia which included looking glasses, window-panes, spectacles, telescopes, burning andmultiplying glasses, sand- or hour- glasses etc. Itis reported that the Portuguese presented a pair of(European) spectacles to an old scholar in theVijaynagar Empire for reading Sanskritmanuscripts, and Rudolfus, a member of firstJesuit mission in Akbar’s court had used spectacles(Qaiser, 1982, pp.71,75). Dānishmand Khan(original name Mullā Shāfīāi), a native of Yazd(Iran) an educated Iranian, who came to India tobuild up his career and became Governor in Delhiduring the reign of Shejehān (1652), had a greatliberal attitude towards science of Ibn Sīnā, worksof Sanskrit scholars and of European experts. Heeven engaged Bernier, the French traveler totranslate European works of Gassendi (1592-

1655) and Descarte (1596-1650), which createdlot of heart-burn among his colleagues. Ibn Sīnā’sworks are still taught in Madrassas on India,without assessment. Maharaja Sawai Jai Singh(c.1688-1743) of Amber (Rajasthan) somehow gotinterested in the stone observatories of Nasīr al-Din al-ūsī (1271) of Maragha and Ulugh Beg(1424) of Samarkand, and built up fiveobservatories in Delhi, Jaipur, Benares, Mathuraand Ujjain to study observational astronomy inIndia. To accomplish the task, he commissioned alarge number of scholars to compile astronomicaltexts and collect relevant information from otherobservatories. In addition, he made effort tomanufacture replica of the novel movableinstrument, astrolabe (well known for its use inCentral Asia) for determining solar time andobservation of a few stars in cosmos suitable forlocal latitude. The stone observatories of coursehad a limited scope and became a place ofhistorical interest with the advent of telescope.

In Indian and Central Asian science, theconcept of geocentric universe and the uniformcircular motion of heavenly bodies has been stillthe major focus. From seventeenth centuryonwards, steel, steam, cannon, maxim gun,printing, etc brought Europe to the peak ofdominance. Most clear and sharp expression ofscientific revolution is found to blossom in Italy(mainly in the north), France, Holland and inEngland.

5. EUROPEAN SCIENCE IN COLONIAL INDIA

(1801–1900)The nineteenth century brought a new

phase in scientific activities in India. It was theperiod of Colonial rule in India, but no concreteeffort was being made to introduce British sciencein its curriculum.

5.1. Urge for European Science: It is the nationalmovement which urged for fresh inputs ofEuropean science. Rammohan Roy (1823), in hisletter to Lord Amherst, wished to have Baconian


philosophy, which by that time became acceptedas a pillar of modern science. Akhshay KumarDatta, an editor of the Tattvabodhinī Patrikā(1843-55), established by Devendranath Tagore,who had working knowledge in French, German,Latin besides Sanskrit, expressed openly for thenew European science. His study room was foundto have been decorated with the portraits of IsaacNewton, Charles Darwin, T.H. Huxley and JohnStuart Mill, besides Rammohan Roy and others.He wrote many tracts on physics, astronomy andother subjects. Bankim Chandra Chatterjee (1838-94) said, ‘Hindu method was almost solely andpurely deductive; observation and experimentwere considered beneath the dignity of philosophyand science’. In this context he refers to theimportance of experiments made by Torriceli &Pascal, heliocentric theory (sun is at the centre instead of earth) of Copernicus, laws of Kepler, lawof Universal Gravitation of Newton and manyothers (Lahiri, pp.48-49). A large number ofindologists, and social scientists took greatinitiatives in favour of western science.Vidyasagar, a great Sanskrit scholar, who servedSanskrit College both as Principal and Secretary,was an ardent votary of western science in Indiaand wished to have a body of men to have westernscience in mother tongue. In his Jiban Carit(1849), he summarized the lives of Copernicus,Galileo, Herschel and Newton, and summarizedthe European knowledge in science in hisBodhadaya (‘Dawning of Sense’, 1851).

There is no end to the list. With theestablishment of three Universities in Calcutta,Madras, Bombay in 1857, many schools andcolleges were started, and leaders took interest inEuropean science, and extracted interestinginformation which is of great historical interest.Five observatories were also established of whichthe Madras observatory (1792) and CalcuttaObservatory (1825) were founded by the EastIndia Company for observing heavenlyphenomena and upgrading geographical and

navigational data. The remaining three were atLucknow (1832), Poona (1842) and another atPoona College of Science (1882) established bythe Indian monarchs for education in astronomicalknowledge.

The colonial period also brought asignificant turn when the Idea of a nationalscientific research institution came through theeffort of Dr Mahendralal Sircar (1833-1904),which resulted in the establishment of IndianAssociation for Cultivation of Science (IACS) inCalcutta in 1876 to organize research in differentfields of European science including lectureprogram through his initiative. On a regular basislectures were delivered on, ‘Thermo-Elasticity’ byMahendralal Sircar; ‘Practical Class in Physics’by Jagadish Chanra Bose; ‘Optical Study ofMusical Sound’ by Father Lafont; ‘Iron Class ofMetals’ by Rajani Kanta Sen; ‘Practical Class inChemistry’ by Ram Chandra Datta; and so on[Vide Indo-European Correspondence, February17, 1886]. Father Lafont gave a demonstrationlecture on ‘Telegraphy without wire’ and said itwas the discovery of his student, Jagadis ChandraBose some years back (Indo-EuropeanCorrespondence, Sept 22, 1897). JagadishChandra’s demonstration lecture on electric light,sewing machine driven by electric motor and X-ray passing through hand and many other topicsare also reported (Indo-European Correspon-dence, 17 August 1888; see also Biswas, 2001,pp.256-331).

Slowly the craze for European sciencebegan to grow. Balaji Prabhakar Modak ofRatnagiri district of Bombay Presidency organizedannual science exhibition at Rajaram Collegeduring Christmas vacation from 1893-96 in orderto acquaint public with west scientific inventions,as reported in Śilpa Kalā Vij–ān, a science journalof 1886 and Karmānuk ( a Poona based monthly)of January 1897 specially with the grandexhibition of 1896. In another exhibition of 1896Modok displayed X-ray machine, camera,


telescope, microscope, coil illustrating Faraday’slaw, Morse’s telegraphy, Edison’s phonogram,water mills, automobiles, engines, along withpractical demonstration on electricity, sound andlight by volunteers.

5.2. Features of Input: The scientific knowledgein Europe made a gigantic leap forward with thefoundation of scientific academies2 for freediscussion and introduction of telescope,spectroscope photographic plate & camera as theinstruments for examining observations. Thescholars like Galileo Galelei (1564-1642) in Paduaand Johannes Kepler (1571-1630) in Tubingenboth supported the heliocentric concept of theuniverse propounded by Nicholaus Copernicus(1473-1543) by using a telescope of refracting typewith a lens (concave or convex) at one end of atube and an eyepiece at the other end forobservation. The telescope of course was not freefrom problems of spherical and chromaticaberrations diffusing images surrounded bycolored halos. This problem was solved later withthe use of a reflecting type of telescope by using amirror (speculum or parabolic) by James Gregory(1638-1675), Newton (1642-1727) and later byJohn Hadley (1682 -1744). It was known thatwhite light passing through a prism breaks intoits component colors. Similar spectrum crossedby lines often dark, more rarely bright, was alsofound by astronomers when a light is passedthrough a slit. Each line of this spectrum isidentified with a given element. This led to thebasis for the discovery of Spectroscope, aninstrument which helps to see the colored spectrumcrossed by thousands of lines, each havingdifferent wavelengths throwing light on thephysical composition of an individual star. GustavKirchhoff (1824-1887) and Robert Bunsen (1811-1899) discovered the application of spectroscope

to chemical analysis successfully discovering theelements — Caesium and Rubidium. Thephotographic plate and camera played equally asignificant place in the analysis of the observation.An image of the object as seen by means of asystem of lenses thrown for a definite length oftime on in a plate or film made of glass, celluloidor other transparent material is important forphotography. A steady effort was also made tocollect the basic texts and articles for knowledgebased on the works of stalwarts in Europeanscience. In addition, a number of concepts inphysical science enriched and influenced Indianperception towards the end of 19th and beginningof 20th century, a summary of which as developed(Brennan, 1997; Rao, 1999; Pal, 2008) will be ofinterest:

Motion of body or bodies was of greatinterest to Newton (1642-1727). To explain, heintroduced definitions and axioms in the same wayEuclid did. His axioms were interpreted as‘assumptions’ by scholar like Ernest Mach.Newton defines mass, momentum, rest, uniformmotion and others. In his Principia (full title:Philosophiae Naturalis Principia Mathematica),he attempted how inanimately nature could beexplained in mechanical terms. He enunciatedthree laws of motion, viz., (i) Every body preservesin its state of rest (velocity zero), or of uniformmotion (moving with constant velocity) in astraight line unless it is compelled to change thatstate by impressed forces; (ii) Change of motion(i.e. the rate of change of momentum) isproportional to impressed force, and takes placein the direction in which such force is impressed;and (iii) To every action there is equal and oppositereaction. To explain his first law in a plane or spaceof 2-dimensions, he developed the definitions ofDistance as OP = r = √(x2 + y2), where r is the

2 Accademia Secretorum Naturae founded in Naples (1560); Accademia dei Lincei in Rome worked from 1603 to 1630; Academiadel Cimento in Florence (1657) survived for ten years; Royal Society for the Improvement of Natural Knowledge in GreshamCollege of London (1662); Academie des Sciences in France (1666); Berlin Academy in Germany (1700), and so on. Italianacademies were involved in the conflicts between science and orthodoxy, while the English, German and French Academies inthe development of utilitarian science arts & technical processes etc.


distance between O (0,0) and P (x,y);Displacement PQ = s = √ [(x′)2 + (y′)2] if the pointP (x,y) moves to another point Q(x′, y′) in time t ;both distance OP and displacement PQ havemagnitude and direction ( known as vectorquantities, also as position vector anddisplacement vector respectively), though theposition vector OP and displacement vector PQhave different directions. Velocity (v), is definedas v = d/dt (s), or v = d/dt (x) and d/dt (y) when ttends to zero along either X and Y axis respectivelyin a one or two-dimensional situation. Velocity isalso a vector quantity, and has the direction ofdisplacement vector. Acceleration (f) is definedas the rate of change of velocity, f = d/dt (v) ordv/dt, when dt → 0 in notation. Momentum = massx velocity = m.v; and so on. In case of 3-dimensional space of three mutually perpendicularaxes, the position vector OP [O (0,0,0) and P (x,y, z) are the coordinates] satisfies the distance ofOP= d′ = √ [(x)2+ (y)2 + (z)2] (in Cartesiancoordinates]. However, in Polar coordinates of 2-dimension, the length OP [where O (0,0 and P (r,θ) the position vector, r being the radius of a circle,and θ is the angle with reference to an axis, sayOX] = magnitude r; if it moves to Q ( r + r′, θ +θ′), then the distance PQ = s′ = √ [(r′)2+(rθ′)2], forthe arc length arc (= rθ′), angle is measured inradian, and r′ being considered perpendicular toeach other, when the change of position is smalland is taken as good as straight. so is in polarcoordinates of 3-dimension. Newton’s second lawintroduces the new conception of force which wasnot very clear during his time in view of hisassumptions of absolute space and absolute timeinvalidating his mechanics for moving objects,including rays of light, although not for the moreslowly moving objects to which Newton appliedit. The second law at best could be defined as‘amount of force’, given by F = m.f, where F isthe force applied which induces a change in thevelocity due to mass (quantity of matter in a body,and f is the acceleration defined as the rate ofchange of velocity. The first two laws of Newton

were derived from that of Galileo (1564-1642).Newton’s third law of course appears somewhatnew which talks about forces exerted by twoobjects to one another are equal and opposite, orin short, when a body is dragged on a surface witha force, say x, then the surface exerts a backwardforce x to the body.

Periodic Motion in a pendulum, asobserved by Galileo, is a regular to and fro motion,which is termed as periodic motion, repeating itselfover an interval of time. Or in other words, whena pendulum bob starts moving from one end pointreaches to the end point of the other side passingthrough a position of rest (known as amplitude),and swings back to the original point movingthrough the position of rest, time taken is knownas time period. Then he introduced a term,frequency as the number of such cycles completedin one second ( i.e. νT = 1, or, ν = frequency =1/T, where T is the time period for one oscillation).The harmonic motion is likewise defined by water-waves at a given point on its surface, with its twoconsecutive position of crests up and down havingamplitude is A or –A along a particular direction,when the time ( t = ½T) changes. The motion ofthe pendulum is almost closer to wave-motion oran oscillatory (vibrational) motion along a straightline, known as simple harmonic motion. In a water-wave motion, the displacement of water particlesis found moving in a direction perpendicular tothe direction of the motion, known as transversemotion. The distance covered between twoconsecutive crests or troughs is known as wavelength (λ). If number of crests (ν) pass through apoint per second, then the distance through whicha crest moves in one second is known as thevelocity of the propagation (V = νλ, V= velocityof propagation, ν = frequency and λ =wave-length).

Another key concept, Law of universalgravitation existing between any two materialbodies, which Newton postulated in his Principia,was known. He made a basic postulate that two


material bodies have always an attractivegravitational force (F) just because of their masses,and the force on each other is, F = G.Mm/R2, whereM and m are the masses of two bodies separatedby distance R between them and G is thegravitational constant. Comparing with Newton’ssecond law and replacing f by g, which gives g =GM/R2 as the acceleration due to gravity. Thevalue of g remains same for all bodies situatedclose to each other on the earth’s surface. Thisgravitation theory of Newton is derived fromKepler’s law of inverse square and he suggestedthat the planets move exactly in accordance withKepler’s three laws, viz., (i) The planet moves inan ellipse which has the Sun at one of its foci; (ii)The line joining the Sun to the planet sweeps outequal areas in equal times; and (iii) The square ofthe time which any planet takes to complete itsorbit is proportional to the cube of its distance fromthe Sun. The first two laws was enunciated byKepler in his book, Astronomia nova (1609) andthe third law in his Epitome AstronomiaeCopernicae (1618). The argument was based onthat the earth is not exactly spherical, in which Rslightly varies from equator to the poles. For abody taken to a height h, R also is changed to(R+h). On this basis, Newton tried to generalizethe motion of two or three bodies (Earth and Sun,or Sun, Moon and Earth) when they attractmutually under gravitational attraction. The lastproblem is known as ‘problem of three bodies’,the solution of which attracted lot of attention fromthe later scholars. The law of falling bodies ofGalileo that two bodies of different masses areallowed to fall from rest they reach the ground atthe same time (only air is the hindrance), whichshowed weight (W= mg) as product of its massand gravity. The kinetic energy is achieved due tomotion when mass and velocity are known[½ m v2]. Work done by a body when it fallsthrough is found by the product of its weight andheight through it has fallen (i.e. mgh). Work donewhen a force makes a displacement by product ofthe force by its displacement (i.e. F. s or – F. s

towards or opposite to the direction of the force,where F = force applied, and s = displacement).This is based on the hypothesis that there istransformation of energy taking place from onestage to another, but total energy is constant.Newton’s law of gravitation, however, was finallymodified by Einstein, which recognized theimpossibility of determining absolute motion andsuggested the concept of space-time continuum.The special theory is limited to the description ofevents as they appear to observers in a state ofuniform motion relative to one another and isbased on two axioms, viz., the laws of naturalphenomena are the same for all observers, and thevelocity of light is the same for all observersirrespective of their own velocity. The importantconsequences of this theory are— the mass of abody is a function of its velocity; the mass-energyequation may be meaningful for the inter-conversion of mass and energy (ε = ½ mc2).Fitzgerald-Lorentz combination accordinglyappeared as a natural consequence of the theory.His general theory which is applicable to observersnot in uniform relative motion, has propoundedthat the presence of matter in space causes spaceto curve in such a manner that the gravitation fieldis set up. The gravitation becomes a property ofthe space itself. The validity of the theory ofrelativity has been confirmed by modernexperiments.

Sound and its propagation, according toNewton, is produced when there is movement ofthe particles (in the medium, say air). It generatesa vibration which produces periodic compressionand rarefaction in the material medium. Thepropagation takes place from one layer to the nextin the same direction of the direction of theparticles generating the vibration. Sound wavesfrom a bell moves as longitudinal waves, as eachparticle of air moves alternately towards and awayfrom the bell. The waves of water on a pond islittle different, the individual particle of watermoves up and down and at right angles to the


surface, i.e. the direction of vibration andpropagation are at right-angles, called transversedirection.. In empty space, there is no materialmedium, so no sound is produced in empty space.The intensity or loudness of sound is proportionalto the square of the amplitude of vibration, its pitchis determined from the frequency of the vibration.Octave is the scales of the musical notes whenthey are spaced by frequencies differing by a factorof 2. Two notes of similar frequencies (differingin pitch only, e.g. frequency í and n í, where n isan integer) form harmonics; when two notesproduced from two sources are close to each otherproducing the same frequency, they are inresonance producing a sound easily detected by atrained year. The quality of the note is understoodfrom quality of mixture of notes produced bydifferent instruments, for notes of each instrumentdepends on a strong component together with asmall admixture of the higher harmonics, whichis somewhat impure.

Light, Newton believed, is nothing butcorpuscles. It moves in straight–line and satisfiesthe law of reflection. Newton, after succeedingBurrow as professor in chair of mathematics inCambridge published a paper, ‘On the theory oflight and colour’ (1801), which revealed the truemeaning of colour. He had made a small hole inthe shutter of his room through which a beam ofsunlight could enter the room and is made to passthrough a prism. He found that the beam hadspread out into a coloured band of light called, aspectrum, in which all the colours of rainbow, fromred to violet, could be seen in the same order as inthe rainbow. He understood and explained thatdifferent colours meant different degrees ofrefrangibility, i.e., a ray of violet light had refractedthrough a greater angle than one of red light at arefracting surface. He arranged for a secondrefraction in a direction at a right angles to thefirst, and found that different colours of lightretained their identities after the second refraction,red remained red, and violet remained violet, each

maintaining precisely the same amount ofrefraction as before. As to light, Newton had noclear idea, in his Opticks, he however expressedit as a strange mixture of corpuscular andundulatory theories, which was just a conjecture.Christian Huygens in his Traite de la Lumiere(1890) described space as a ‘very subtle and elasticmedium’ and thought that a luminous object setup disturbances at this medium at perfectly regularintervals of time. These regular impulses producedregular undulations in the medium and propagatedin all directions in the form of spherical waves.Hooke suggested that light might consist oftranverse waves, and each particle of ether movedat right angles to the direction in which the lightwas traveling. He implied that a ray of light had‘sides’ in the Newtonian sense, one in the directionin which the particle moves, and the other in thedirection of the wave, which is at right angles tothe direction. Newton was aware how the use oflenses, their properties and geometrical knowledgehave brought forth the use of telescope at the handsof Kepler and Huygen for viewing distant objects.The correct law of refraction discovered by W.Snell (1621) of the Leiden university emphasizedby Descarte was also known to him. That the lightmoves in waves, and its properties werepropounded by Grimaldi (a Jesuit professor atBologna), Huygens, Franhaufer and Fresnel.Grimaldi, in his book, Physico de Lumine,Coloribus, et Iride, first used three screens holdingparallel to each other, first having one hole, secondhaving two holes, and the third having no holeWhen a source of light is hold before the hole offirst screen, the light passing through the holes ofthe first two screens is projected on third screen,it was found that the light at the two points in thethird screen is well lighted, but the intermediateareas also showed rhythmical alteration of lightand darkness, having the same origin as rainbow.It provided a satisfactory understanding that thelight moves in waves. There were experimentsmade by other scholars justifying the phenomena.By the same time Young supported this


interference pattern in light and said that it ispossible for monochromatic life., i.e., with lightof one single spectral colour. If white light is used,the different constituent colours of light are ofdifferent wavelengths, and produce differentpatterns on the screen, the result being complicatedpatterns of vivid colours. From the dimensions ofthe pattern formed by any single colour of light, itwas possible to deduce the wavelengths of light.Fresnel found in 1821 that red light has about 4000waves to the inch, and violet light about 80,000,the intermediate colours being of courseintermediate in wavelength. The undulatory theoryhad intimate connections that the time of travel ofa ray of light attains its minimum value along thepath actually travelled by the ray. H.L. Fizeaumeasured the velocity of light in air and found aspeed of light about 315,300 km per second in1849, while J.L. Foucault, his compatriot,performed a series of experiments by a number ofdifferent methods, and obtained a more accuratevalue of 298600 km per second. Michelson hasmeasured the velocity as about 299,770 km(186,300 miles per second). Of course it was foundless rapid in a denser medium as per Fermat’stheorem. This fixed a final nail in the coffin of thecorpuscular theory of light of Newton.

Polarization is an important property oflight. Huygens observed that when a slab of glassis laid on a page of print, letters could be seenclearly, although a little displaced on account ofrefraction in passing through the glass. But if aslab of calcite (Iceland spar) is laid on the page,each letter gets double, since calcite hasremarkable property of breaking light into twodistinct rays travelling in different directions, andit is a case of double refraction. Light is atransverse wave, the vibrations themselves beingat right angles to the direction of the light path. Inits isotropic property of vibration it is known asun-polarized, as it moves in all direction. In plane-polarized light, the vibrations confined to oneplane, known as plane of vibrations, and the

vibrations which are confined to the plane at rightangle, is known as the plane of polarization. Thepolarization to a vibration is strictly confined to aparticular direction. It is done through passage ofun-polarized light through thin plates ofTourmaline crystals. However, polarizationthrough solid crystalline bodies, because of theirspecial crystal structures, can be adjusted topreferred directions.

Magnetic properties, as described inGilbert’s publication of De Magnete (1600), dealtmainly with magnetic materials and magneticproperties. Only one small chapter dealt withelectricity. Magnetic materials had a practicalvalue in the science of navigation. The mariner’scompass—a small pivoted magnet had beeninvented by the Chinese in the eleventh centurywhich was introduced into Europe by theMohammedan sailors. Among the magnetismmaterials —Lodestone (an oxide of iron),Ferromagnets (Iron & Nickel), Bar magnet(suspended by a thread points towards north-south,aligning along a direction towards geographicalnorth-south axis of the earth) were quite known.Two poles of a bar magnet near its two endsindicate charges equal in strength but opposite incharacter. Magnetic moment of a bar magnet iscalculated by multiplying strength or magnitudeeach pole by its distance between the two poles.Magnetic moment is a vector quantity, and itsdirection is conventionally taken from south tonorth pole, The north (north-seeking) pole of onemagnet always attract south (south-seeking) poleof the other magnet, where as two like poles repeleach other. Earth is a huge bar magnet as it containshuge magnetic materials. But the magneticcompass indicating north of earth means that thegeographical north of earth has the same magneticcharacter as the south pole of a bar magnet. Themagnetic are actually the impact of electriccurrents passing through the materials, i.e. atomsand molecules of the material carry current on amicroscopic scale, and the magnetic moment is


the fundamental property of these subatomicparticles. In a ferromagnetic substance, themagnetic moments are usually forced to align ina certain direction by suitable physical methods.

Electric property or electricity in therubbed object, Gilbert explained, that when a pieceof amber is rubbed in the proper way it acquiresthe power of attracting light objects. C.F. du Fay(1733) tried to explain the phenomena of attractionand repulsions on the supposition that allsubstances contained two kinds of electric fluids,usually present in equal quantity, and thenneutralize one another. Benjamin Frankin (1752)suggested that lightning was an effect of electricconduction and confirmed this in his famous kiteexperiment. In 1773 physicists became alsointerested in the shocks produced by so-calledelectric fishes, the Torpedo and the Gymnotus.George Simon Ohm (1827) replaced the vaguedescriptions by a more exact scientificterminology, and introduced precision into ideasof quantity of electricity, current strength andelectromotive force. Faraday by 1800 introducedmost of the present day terminology ofelectrochemistry, the process of decomposing asubstance (electrolysis) into its simplerconstituents by a flow of electricity, the resolvedsubstance he called ‘electrolyte’. Electricity thusfar linked with light and heat, and the foundationswere laid on electric lightning and heating. But afar more interesting is the connection betweenelectricity and magnetism.

Electromagnetism, by 1800, is believedby the physicists that there must be someconnections between electricity and magnetism.H, C. Oersted (1820) of Copenhagen found that amagnetic needle which was balanced on a pivotor hung by a thread is deflected from its positionwhen an electric current flows in its vicinity. Thissingle observation prompted the discovery oftelegraph, the tapping of telegraph key (at onepoint in an electric circuit alternately making and

breaking the circuit hundreds of miles away). Thesame observation made it possible also to discoveran instrument called, Galvanometer, for measuringintensity of an electric current from its amount ofdeflection. The French physicist Andre MarieAmpere immediately understood the importanceof Oersted’s experiment and changed twomagnets, which deflect one another in proximity,replaced one magnet, also the other magnet withwire carrying currents, the effect remaining thesame. He obtained the result what he anticipatedthat two currents attract or repel one another justlike two magnets. Michael Faraday (1791-1867),an assistant to Sir Humphry Davy at the RoyalInstitution, London, wondered whether a currentflowing in a circuit might not in the same wayinduce another current in a nearby circuit. He triedmany ways but without success, but soon foundthat the motion of a magnet in the proximity of acircuit induced a current in the latter. In this waythe mechanical work of moving a magnet couldbe used for producing electric current. This madethe basis of the structure and operation of dynamo(mechanical production of electric power), and allforms of electric transport—trains, trams,elevators and so on (by following a converseprocedure of transforming the energy of an electriccurrent into mechanical energy). In thisexperiment Faraday hinted but not clear about theline of force which the magnet or electric chargesare acting in case of ether which was imagined tofill all space. Clark Maxwell (1831-1879) followedthe line of Faraday and published a paper in 1864in mathematical language, by attributing electricand magnetic action to pressures and tensions inthe ether showed that any disturbance created inthe ether by electric and magnetic changes wouldbe propagated through it in the form of waves.The speed with which these electromagneticwaves would travel in space is the same as thespeed of light. In such waves the electric andmagnetic forces would be at right angles to oneanother, and move also to the direction in which


the wave was travelling. These waves would bepropagated at a uniform speed which could becalculated and proved, to within the limits ofexperimental error, to be precisely equal to thespeed of light (Maxwell’s Electromagnetic theory).Further, Maxwell pointed out that theseelectromagnetic waves would extend over a wideband of wave lengths and exhibit properties of heat(infrared), light, ultraviolet, x-rays, γ-rays.Heinrich Hertz (1857-1894) in 1887 succeededin making electrical sources emit waves and wereshown to possess all properties which Maxwell’stheory required of them, as well as knownproperties of light-waves, except that they wereof much greater wavelength. They were in factwhat is now known as ‘radio-waves’ of very shortwavelength.

Radiation, Wavelength, Frequency andCharge have important relationship with matter.It was observed by some experimenters by end of19th century that their electric instrumentsdischarged themselves with out any apparentreason and conjectured that there must be somekind of radiation (the invisible rays that is emittedfrom a source). They were of the same intensityby night and by day, could arrive at the southernhemisphere when the Milky way was not visible,it was thought it might be extra-terrestrial and theresult of some cosmic process, and became knownas ‘Cosmic radiation’. Following Kirchhoff, theinventor of Spectroscope by 1869, Max Planck in1900 first noted that all objects radiate energy. Ablack body (a theoretical object) absorbs allfrequencies of light of various intensities of wavelenghts, and when it is heated it radiates allfrequencies of light.

Radiation is described in terms of itswavelength (distance between the successive wavecrests). So is frequency as number of crests thatarrive per second. It was also noticed that whenthe wavelength is short, the frequency is high andvice versa. Various forms of radiation compose

the electromagnetic spectrum. The radio waveshave very long wavelength (very low frequencies)followed by infrared heat radiation, visible light,ultraviolet radiation, x-rays, gamma and cosmicrays with very shorter wavelength (very highfrequencies). Ordinary sunlight being a mixtureof waves of seven colours (seen sometimes as arainbow) have continuous range of frequencies.The smallest frequency (having the largestwavelength) produce a sensation or radiation ofred colour in our eye, and the largest frequency(having the smallest wavelength) violet in the eyein the normal visible range (wavelength varyingfrom 10-7 to 10-6 meters, roughly 10-5 cm). But thenumber of different frequencies in the highfrequency range is greater than the number in thelow frequency range.

It was argued that if a blackbody radiatesall frequencies of electromagnetic radiationsequally, then virtually all the energy would beradiated in the high frequency range. Infrared hashigher wavelength (0.8 µm to 10-4 metres) thanimmediately following red, and ultraviolet haswavelength smaller than violet (4×10-7 to 5×10-9

meters), both are invisible to human eye. Abovethe infrared, the spectrum of wavelengthsincreases through the waves of micro andmillimeter wavelengths and radiowaves in therange of metre wavelengths. Beyond ultravioleton the other side, x-rays (5×10-9 to 6×10-12 metresapproximately) and γ- rays (10-12 to 10-13 metres)which is emitted by atomic nuclei, have extremelyshort wavelengths. X-ray is also measured inAngstrom unit (1 Angstrom = 10-8 cm or 10-10

metres). The frequencies are measured in Hertz(Hz) after the name of Heinrich Hertz, who firstsucceeded in making electrical sources in thelaboratory emit waves. Hertz, SI unit of frequencyof a periodic phenomenon is so named and derivedin which the periodic time is one cycle per second.Other bigger units are kilohertz (1 kHz = 103 cyclesper second), and megahertz (1 MHz = 106 cyclesper second) [Fig. 1].


Periodic table of element, structure ofatom, atomic number, mass, and charge openedup as another very important area for study ofmatter in this context. From the position of anelement in the periodic table its properties maybe predicted with a fair measure of success. Byseventeenth century almost twenty elements –Copper (Cu), Iron (Fe), Silver (Ag), Gold (Au),Mercury (Hg), Carbon (C ), Tin (Sn), Lead (Pb),Antimony (Sb), and Sulfur (S), Zinc (Zn), Cobalt(Co), Nickel (Ni), Platinum (Pt), Arsenic (As),Bismuth (Bi), Nitrogen (N), Oxygen (O),Phosphorus (P) and Hydrogen (H), were roughly

identified by various countries.. Robert Boyledescribed them as simple, unique, unmixedmaterial bodies and were made up of other similarand dissimilar bodies. Lavoisier (1743-1794) ofFrance in 1789 first published a list of 23 elements,following a method of chemical decomposition,and adopting a method of weighing reactants andproducts in chemical reactions. He for the firsttime explained the nature of combustion, and thatwater is a chemical compound of two gases—hydrogen and oxygen, and air consists ofmolecules of two gases— nitrogen and oxygen.The word ‘gas’ was commonly used in place of

Fig. 1. Electromagnetic Spectrum – Radiated energy in terms of wavelength and frequency; when the wavelength isshort, the frequency is high and vice versa

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‘element’. Priestley discovered nitric and nitrousoxides, hydrochloric acid gas, sulfur dioxide andseveral other gases. With more and moreunderstanding of the properties of elements, anurge was felt to arrange them in an order accordingto their properties. By 1869, Mendeleyev (1834-1907), the great Russian chemist, published aperiodic table, but his table had many gaps and hehad no idea of inert gases (or noble gases) –Helium(He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon(Xe), Radon (Rn). These inert gases have nocolour, odour, taste, and also do not reactchemically with other elements. In 1896 Becquereldiscovered Uranium as radioactive material(radioactivity) and Madam Curie Polonium (Po).For an over all idea of elements, the concept ofthe structure of atom was a necessity. J.J.Thompson (1904) discovered ‘electron’ as animportant constituent of atom of all elements, andproposed that it has negligible mass, and negativecharge too. Thompson and Rutherford of theCambridge University (UK) described atomhaving nucleus at the core consisting of neutron(neutral charge) and protons (positively charged),surrounded by electrons (negatively charged).They assigned mass number (sum of protons andneutrons in the nucleus), atomic number (equal tothe number of protons in the nucleus). Atoms areneutral because they have the same number ofprotons and electrons. Isotopes of element havingatomic number but different mass numbers werealso recognized. By 1900 Max Plank believed thatatoms were the basic building blocks of nature,and energy is continuous, radiated in waves,irrespective of heat, sound and light waves. Heintroduced the word, ‘quantum’ (plural ‘quanta’)as the unit of energy radiation, and formulated arelationship (ε = hf, where ε is the unit energyradiation, f = frequency of vibration, h = Plank’sconstant) by saying that if quantum’s energy andfrequency of radiation times are inverselyproportional to the wavelength, then both weredirectly proportional, as accepted later on by NeilBohr. In 1913 he proposed that electrons move

around nucleus in orbits, and each orbit has aquantum number having a specific energy.Electron can jump from one orbit to another, andin such a case energy change occurs accompaniedby absorption of radiation (or, ε2 – ε1 = h f, i.e. h fis the energy changes from 1st orbit ε1 to 2nd orbitε2, where f = frequency of radiation, h = Plankconstant, an extremely small number andrecognized as one of the fundamental constantsof the universe = 6.626 × 10-34). Spectrometersare often used to measure absorption and emissionof light for electron jump. The frequency ofradiation is again related to wavelength ( i.e f =c/λ, where λ = wavelength, c = velocity of light =3 x 108 ms-1). Electron, just like light, has waveproperties, known as orbitals, and rules have beenformulated for calculating energies of differentelectron orbitals. The systematic classification inthe Periodic table with their physical propertiesalong other seminal ideas helped the physictsgreatly. Thousands of compounds were identifiedfrom naturally occurring substances and manyhave been discovered in the laboratory. As manyas 110 elements are known, vide Periodic Table[Fig. 2].

The knowledge confined to variouselements with atoms as basic units was initiallythought to be highly empirical, until Mendeleyevcould put them into a profound order and forecastthe existence and properties of the thenundiscovered elements by means of his originaltable, supported by vast array of spectroscopicdata, and to arrange them in the Periodic Table. Itwas also understood that atom, within theframework of quantum mechanics, was not anelementary particle, rather a composite object,with electrons orbiting around a central heavynucleus (with linear dimension 10-4 or 10,000times smaller than the size of the atom) in a‘shells’, defined by four elements— atomicnumber, mass number, periodicity, and similarities,in accordance with the Pauli Exclusion principle.The same theoretical framework provided a


Fig. 2. Periodic table : Elements display similar properties at regular periods and elements in a group are similar

natural understanding of molecular bonds havingdiverse chemical properties of matter in anintegrated fashion. This is specially important, forit introduces for the first time an idea of groupconcept in the understanding of matter.

6. GOLDEN PERIOD OF PHYSICAL SCIENCE IN

INDIA (1901–1960)By the University Act of 1904 the three

universities of Calcutta, Madras and Bombay wereallowed to conduct teaching and research onphysical science and other subjects. A largenumber of qualified teachers and research studentswent to Europe for various expertise and higherdegrees. Research in physical science started withgreat vigour in all these universities. A survey ofresearch output made by S.N. Sen and SantimoyChatterjee (IJHS, 1992-93) in the field of physicalscience made during 1800-1950 will be of interest.In this context, it may also be noted that there are

many papers left out from this list, for which INSABiographical M emoi res of well-known scientistsand similar publications may be consulted.

A few prominent names in this list, are —Jagadish Chandra Bose, C.V. Raman, MegnadSaha, S.N. Bose, S.K. Mitra, Homi Bhava, S.Chandrasekhar, and others. The European sciencepaved the way but Indian physical scientists raisedthe boundaries of knowledge in the field to a greatheight. Publications were mostly done in topinternational journals like Transaction of the RoyalSociety (Edinburg), Transaction of the OpticalSociety (London), Transaction of the FaradaySociety (London), Transactions of the ChemicalSociety (London), Nature (London), and manyother Journals abroad, besides Journals in India,like the Proceedings of the Asiatic Society ofBengal (1776), Bulletin of the CalcuttaMathematical Society (1908) etc. All contributorswere extremely motivated and took research as a


Research Output during 1901-1960

Electricity, Conduction, 19 papers in 19th & 204 Jagadish Bose (109 papers), P.C. Mohanti (15), S.K.Discharge & Biophysics in 20th century (first half ) Kulkarni Jatkar (14) and others

Acoustics 2 papers in 19th & 258 in C.V. Raman (58 papers), R.N. Ghosh (29), M. Ghosh20th century (first half) (15), S. Parthasarathy (13) and others

Heat & Thermodynamics 8 papers in 19th & 204 in M.N. Saha (17 papers), D.S. Kothari (16) and others29th (first half)

Magnetism & 12 papers in 19th & 302 in D.M. Bose (12 papers), A. Bose (11), S.S. BhatnagarElectromagnetism 20th century (first half) (32), K.S. Krishnan (20) and others

Optics & Radiation 5 papers in 19th & 659 in C.V.Raman (113papers), K.S.Krishnan (28), R.S.20th (first half) Krishnan (24), S. Bhagavantam (19), G.N.

Ramachandran (16), K.R. Ramanathan (15) and others

Atomic & Molecular 104 papers (1920-1950) D.M. Bose, C.V. Raman, K.R. Ramanathan and othersStructure

Crystal Structure & 313 papers (1920-1950) C.V. Raman (35 papers), K.S. Krishnan (45), S.Properties Bhagavantam (16), K. Banerjee (15) and others

Radioactivity, Nuclear 417 papers (1910-1950) D.M. Bose (16 papers), M.N. Saha (14), R.S. Krishnanphysics & α-,β-,γ-rays, (12), H.J. Bhabha (53), K.C. Kar(18), Vikram SarabhaiCosmic rays (12) and others

X-rays 236 papers (1920-1950) C.V. Raman (19 papers), B.B. Ray (25), G.N.Ramachandran (10), S.R. Das (13), P. Krishnamurti (12)and others

Astronomy & 80 in 19th & 431 in 20th M.N. Saha (26 papers), N.R.Sen (26), A.C. BanerjeeAstrophysics century (first half) (14), D.S. Kothari (20), V.V. Narlikar (11), S.

Chandrasekhar (78),P.L.Bhatnagar (10) and others

Geophysics 200 papers in 19th & S.K. Mitra (72 ), M.N. Saha (11 papers), K.R.617 in 20th century Ramanathan (28), S.K. Banerjee (27), S.R. Khastagir(first half) (12) and others

Statistical mechanics, S.N. Bose, K.C. Kar, K.K. Mukherjee and others.Wavemechanics &Wave statistics

way out in their national movement and wantedto assert that they are no less competent thanEuropean scholars. A few of these scholars, asidentified, will be taken here to have an idea oftheir contributions in the field.

In nineteenth century there was practicallyno research in physical science in India other than

the effort taken by IACS at Calcutta. Sir JagadishChandra Bose of Presidency College, Calcutta,gave regular lectures at IACS and conductedresearch in short electromagnetic waves and othertopics which achieved international fame in spiteof various limitations in space, instruments, fundsand so on. His biography and contribution alongwith others in applied research are considered here


as a case study and will be of interest. It is knownthat most of his instruments were locallymanufactured with great novelty.

6.1. Jagadish Chandra Bose

Jagadish Chandra wasborn on 30 November 1858 inthe town of Mymensigh inBengal, where his father,Bhagwan Chandra Bose wasthen posted as DeputyMagistrate. He had his schooleducation in Faridpur, andobtained his BA degree inPhysical Sciences from St Xavier’s College,Calcutta. He went to Cambridge for Triposeexamination. For this examination he had to taketraining both in physical and biological scienceswhen he came under the influences of well knownteachers (Lord Rayleigh, Sir James Dewar, SirMichael Foster and Francis Darwin). In 1884 heobtained his degrees in BA (CambridgeUniversity) and BSc (London University), andcame back to India and joined Presidency College,Calcutta in 1885 as Assistant Professor of Physics.He obtained his D.Sc. from London University in1896, and made a number of visits for lecture toursto Europe and USA between1896 to 1930. He wasrecognized as Jagadish Chunder Bose during hislife time. He retired as professor of Physics fromthe college after 30 years’ service. He was knightedin 1917 and elected Fellow of the Royal Societyin 1920. After his retirement from PresidencyCollege in 1915, he was offered the post of PalitProfessorship in Physics of the CalcuttaUniversity, but he regretted his inability to acceptit in order to fulfil his dream to build up a researchinstitute on the model of the Royal Institution, nowknown as Bose Institute (Bose & Ray, p.274). Hecollected all his personal savings and publicdonations for this institute which was build up atUpper Circular Road, Calcutta, and inauguratedin 1917. He became its first Director and continuedhis investigations here till to his death in 1937.

The Bose Institute carries his touch, paintings,frescoes, beaten metal works, portraits of greatsavants of his time like Nandalal Bose,Abanindranath Tagore, Gaganendranath Tagore,Rabindranath Tagore and others.

Jagadish Chandra published 128 researcharticles besides 11 monographs (vide his list ofpublications in the Biographical Memoires, Vol I,pp.7-21, published by INSA). His scientificpursuits may be classified in three phases:

1894-1900: Articles include his work onpolarization of electric rays by double refractingcrystals, construction of electro-polariscope,determination of wavelength of electric radiation,construction of apparatus for the study of electricwaves, construction of a compact apparatus forgeneration of electromagnetic waves ofwavelength 25 mm to 5 mm, and analysis of theirquasi-optical properties; rotation of the plane ofpolarization of electric waves, self-recoveringcoherer and the study of cohering action ofdifferent metals; electric touch and the molecularchanges produced in matter by electric waves;

1901-1907: Investigation concerned with behaviorof plant tissues under different modes ofstimulation, construction of delicate and accurateinstruments for automatic recording of plantresponses; preparation of inorganic models of bio-physical phenomena underlying electrical andmechanical responses to stimulation, thetransmission of excitation in plant and animaltissues, and of vision and memory; results arepublished in his book, ComparativeElectrophysiology (1907);

1907-1933: Investigation of response phenomenain plants the complexity of which lies intermediatebetween those of inorganic matter and of animals.

Jagadish Chandra first focused his researchattention in the construction of a compactinstrument for the generation of shortelectromagnetic waves and to study their opticalproperties. Most of the scholars believe that he

Fig. 3. Sir JagadishChandra Bose(1858-1937)


was possibly influenced by Oliver Lodge’s paperon “Heinrich Hertz and his successors”, publishedin 1894. However, immediately after joiningPresidency college in 1895, he started hisexperiments in a small enclosure (laboratory)adjoining a bath room at the College, on refraction,diffraction, polarization and transmission ofmillimeter waves. He was a great innovator. Toreceive the radiation, he used a variety of differentjunctions connected to a highly sensitivegalvanometer. He plotted in detail the voltage-current (non-linear) characteristics of hisjunctions, and devised ingeniously diffraction-grating for millimeter waves by using polarizers,made of cut-off metal gratings of a book Railwaytimetable with sheets of tinfoil interleaved in thepages, and inserting these plates at regularintervals. He even used twisted jute bundles inorder to rotate polarization of millimeter waves.In 1895 he demonstrated wireless communication,rang a bell and exploded some gunpowder (placedin room at a distance and separated by more thanone wall) using millimeter waves in Calcutta.Thisachievement was reported in 1896 in DailyChronicle of England thus: ‘The inventor (J. C.Bose) has transmitted signals to a distance ofnearly a mile and herein lies the first and obviousand exceedingly valuable application of this newtheoretical marvel’ (Emerson, p.33;Bhattacharyya, p.46). In December 1895 Russianscholar Popov who was doing similar workexpressed that he was still hoping to achieveremote signaling. However, in May 1897 Marconiobtained patent right on wireless signaling, whichwas already reported a public demonstration ofwireless signaling in 1895 in Calcutta.

Bose invented a diode detector ofwireless waves, then known as self-recoveringcoherer. He fixed an emitter and a detector,attaching his emitter of microwaves in acylindrical or rectangular metal tube, a precursorof wave guides, and used an antenna pyramidalelectromagnetic horn in his compact electric

apparatus for better electric radiation. This waspossible by selected metals, by adjustment ofpressure and applied e.m.f. In the process heclassified two groups of metals for his detector,i.e. in positive group—galena, iron, nickel,magnesium, tellurium, in which current increasedin the circuit with absorption of radiation, and innegative group—potassium and speciallyprecipitated silver powder in which galvanometercurrent is decreased on absorption of electricradiation. The current voltage curves with thecurrent axis were found to be concave with thepositive groups, and convex with the negativegroups. Bose found galena crystal as a perfectdetector not only for absorption of perfectradiation, but also for absorption of light radiation,from ultraviolet to infrared. He also explained theconstruction of a reflecting metal strip concavegrating with which he measured the wavelengthsof the electric radiation given out by one of hisradiators. These he found to be of the order of 20mm wavelength. On invitation from Rayleigh,Jagadish Chandra reported about his microwave(millimeter-wave) experiments to the RoyalInstitution and other societies in England withwavelength ranging between 2.5 cm to 5 mm(Emerson, p.33). Patent rights for the use of galenacrystals for making receivers both for shortwavelength radio waves, for white and ultravioletlight were granted to him in 1904. K. F. Braunand G. Marconi (joint Nobel Prize winner of 1909)in their Nobel lecture referred initial problem ofincreasing the range of spark gap in wirelesstransmitter, how after 1901 they have sorted outthe problem by using galena (lead sulphide) basedcontact detector discovered by Jagadish Chandra(Bondyopadhyay and Banerjee, pp. 28-29) is notclear. Pearson and Brattain in their report on‘History of Semiconductor Research, 1794-1955’(Proceedings of I.R.E., Vol. 43) gave priority toBose for the use of semiconducting crystals asdetector of radio-waves. Sir Neville Mott, NobelLaureate in 1977and expert on solid-stateelectronics remarked on this discovery of Bose


that ‘J.C. Bose was at least 60 years ahead of histime’ (Emerson, p.33). In the Royal Society lectureBose also speculated on the electromagneticradiation from the sun, so-called solar emissionor radiation for which solar or terrestrialatmosphere might be responsible.

By the end of 19th century, JagadishChandra turned his interest from electromagneticwaves to response phenomena in plantsincluding studies of the effects of electromagneticradiation on plants. His studies produced byelectricity on living and non-living substances waspresented at the ‘International Congress inPhysics’ in Paris (1900). For further investigation,he stayed in DavyFaraday Laboratory of the RoyalInstitution and in about two years time, hepublished eight papers, compiled in a monograph,Response in the Living and Non-living on the basisof extensive experiments on the animal tissues likemuscles, and electrical excitation in other tissueslike nerves or retina, stimulation by light (in retina)producing changes. He found that not only animaltissues, but vegetable tissues also make similarelectric responses under various kinds of stimuli(mechanical, application of heat, electric shock,chemicals or drugs). As regards response toinorganic systems, he observed that certainchemical dissolved in the water can increase theelectric current while other chemicals can depressthe flow of electricity. This is somewhat analogousto the effect of stimulants and depressants on livingtissues.

In the third phase, he concentrated onBiophysical Studies results of which are publishedand compiled in his book, ComparativeElectrophysiology (1907). It shows that he deviseda number of inorganic models providing analogousresponse effect in metals to varieties of stimuli.He has also attempted to group together theresponse effects in living and non-living matter,which are mechanical (i.e. the response for changeof length); electrical (like change in conductivity,production of galvanometric current); and those

which result in transmission of excitation. He alsodevised special models to illustrate the physicalbasis of memory. His query was, how the memoryis storing information? If the information is storedin a location in a living or a mechanical system,how it could be made use of ? If it is stored in thebrain, in which side of the brain it is stored?Nothing was known during his time. What Bosedid he used ferromagnetic properties of matter toprovide as a model for storage of information asmemory. He prepared a surface coated with aphosphorescent paint, in which a pattern had beencut out, is covered with a cardboard. Then thiscovered screen is illuminated for sometime andlight is extinguished. The cover is then removedand it was found that the illuminated portion underthe cover glows brightly for some time. Thephosphorescent screen is again exposed to diffuseillumination, it was found that the area which hadbeen previously exposed to light begins to glowmuch earlier than the unexposed portion of thescreen. This, according to Bose, can be used asmodel of revival of latent memory by an act ofwill. Bose has also given other models of memory.This has been reported by Moss (Proceedings ofI.R.E., vol.43, p.1869 in his review ofPhotoconductors.

Jagadish Chandra used local materials forhis research and was far ahead of his time. BoseInstitute was the epitome of his dreams. D.M.Bose,the second Director was the torch-bearer of theinstitute along with others. Besides being a greatscientist, his scientific articles in Bengalirejuvenated great spirit in Bengali mind.

6.2. C V Raman

Chandrasekhara VekataRaman, the second son of R.Chandrasekhara Iyer (agraduate in Physical scienceand teacher of physics andmathematics in a local college)of Trichinopoly in South India, Fig. 4. C.V. Raman

(1888- 1970)


was born on November 7, 1888, and died on 22November, 1970 at age of 82. He had acquired aremarkable mastery in English language anddeveloped a test for science studies at a very earlyage. He had his graduation from PresidencyCollege, Madras, in 1904 with first class andobtained Gold Medal in Physics, besides a collegeprize for English essay writing. During his M.A.course, he had no regular classes in the first yearand prepared himself for exam in mathematics,and also in physics by reading classical books ofphysics, like Helmholtz’s Sensations of Tone,Rayleigh’s Theory of Sound, Ewing’s MagneticInduction in Iron and other Metals, and so on. Inthe second year he took literature, history,economics, and other allied subjects, and clearedM.A. in first class obtaining record marks.

He passed also the Finance exam in 1907in which he stood first and got busy for the nextten years with his appointment in Indian FinanceDepartment with postings in Calcutta, Rangoon,Nagpur and again in Calcutta. Here in Calcutta hecame to know about IACS founded byMahendralal Sircar in 210 Bowbazar Street(central Calcutta) and started his research workin physical science in his spare time beyond officehours and on holidays. From his last posting inCalcutta in 1911, he became a sensitive and seriousin his research work and got involved forsystematic publications from this centre, andremained attached with it for the next 20 years. In1917 he joined Calcutta University as PalitProfessor on the invitation of Sir AsutoshMookherjee, the then vice-Chancellor of theUniversity. Raman was elected FRS by the RoyalSociety of London in 1924, knighted by BritishGovernment in 1929, Hughes Medal of the RoyalSociety in 1930, and became Noble Laureate inPhysics the same year. He also received honoriscausa the D.Sc. degree from many universitiesoutside and in India. He was a brilliant scientistand had an electrifying personality and a greatleader in science. His scientific work has several

distinct phases and was mainly focused to clearsome of the doubts and mysteries of the universe.Raman’s scientific work is varied in its range anddepth (vide, list of his paper in C.V. RamanCentenary Supplement published in Science andCulture, pp. 41-51), even though the number ofpublished papers may be more. However, the workareas may be listed in phases thus:

1906-1920: Worked on Newton’s rings inpolarized light, Huygen’s secondarywaves,acoustical observations, Doppler effect andmolecular scattering of radiation; [paperspublished from IACS independently and/or withcollaborators — S. Appaswamiyer, A. Dey, P.N.Ghosh];

1921-1932 (at Calcutta): Study included soundsof musical instruments, of splashes, vowel sounds,whispering galleries, colours of mixed plates,visibility of distant objects, colour of the sea,molecular scattering of light in liquids & liquidmixtures, solids & amorphous solids, and densevapours & gases, by liquid and solid surfaces, byliquid boundaries and its relation to surfacetension, by anisotropic molecules; molecularstructure of amorphous solids, moleculardiffraction of light, molecular scattering of lightin water and colour of the sea, ice in glaciers,spectrum of neutral helium, diffraction of light byspherical obstacles, by metallic screens, bytransparent laminated screen, X-ray diffraction inliquids, Compton effect, magnetic doublerefraction in liquids, electrical double refractionrelating to polarity and optical anisotropy ofmolecules, Maxwell effect in liquid, Comptoneffect & Kerr effect verification, secondaryradiation & new class of spectra, change ofwavelength in light scattering, polarization ofscattered light, molecular spectra in infrared, newradiations by light scattering, molecular scatteringof light (Noble Lecture, 1930), photon spin fromlight –scattering, Doppler effect in light-scattering;[papers published independently from IACS &Calcutta University and/ or with collaborators—


B Banerjee, S Kumar, A Dey, G Sutherland,K Seshagiri Rao, K R Ramanathan, A S Ganesan,K S Krishnan, L A Ramdas, S K Datta,I Ramakrishna Rao, C M Sogani, S Krishnamurti,S Bhagavantam, S W Chinchalkar].

1933-1948 (at IIS, Bangalore): Colours in birds,shells, diffraction of light by high frequency soundwaves, ultrasonic waves, acoustic spectrum oflight, Haidinger’s rings in soap bubbles, new X-ray effect with change of frequency, quantumtheory of X-ray reflection, spectroscopicinvestigations of solid and liquid states, physicsincluding nature, origin, structure, properties andvibration spectrum of crystal lattice of diamond,infrared spectrum and vibration spectra of crystals,and X-ray reflection of crystals; [papers publishedindependently and/or with collaborators—B VRaghunatha Rao, N S Nagendranath,K Subbaramiah, V S Rajagopalan, P Nilakantan,G R Rendall, S Ramaseshan, S Bhagavantam].

1949-1970 (at Raman Research Institute,Bangalore): Diffraction of light by transparentspheres and spheroids, luminescence of diamonds,vibration spectra of crystals and specific heats,origin of iridescent crystals ( potassium chlorate,agate, opal, labradorite, moonstones, shells) —their structure & behaviour, X-ray studies ofpolycrystalline gypsum, fibrous quartz & crystals,thermal energy and elasticity, specific heat ofcrystals & alkali halides, quantum theory andcrystal physics, diffraction of X-rays by diamond,infrared behaviour of diamond, sodium fluorideand their structure and behaviour, light, colour andvision, floral colours and physiology of vision,colours of roses, varied colours of verbena; [majorareas, papers published independently and/or withcollaborators—S Ramaseshan, J Jayaraman, AJayaraman, D Krishnamurti, M R Bhat, A KRamdas, K S Viswanathan, and S Pancharatnam].

Raman concentrated in the first phasemainly on vibrations, sound and musicalinstruments (bowed strings, violin, pianoforte,

stringed instruments—tanpura and veena, andmusical drums). After becoming Palit Professorof Physics in the University of Calcutta in 1917,he continued his research in IACS. During tour toEngland in 1921 as a delegate to the UniversitiesCongress at Oxford, he visited St Paul Church andwas struck by the well-known whispering galleryof the dome and made a study of the phenomenon.After returning to India he made a thorough studyof a number of whispering galleries, e.g., the GolGumbaz at Bijapur, the Victoria Memorial atCalcutta, the Granary at Bankipur, Patna and theCalcutta General Post Office. During his returnjourney from England in ship he got struck withblue colour of the sea and focused his researchalso on scattering of light. His research, known asRaman Effect, earned him Noble Prize in 1930during his work in Calcutta. From 1933 onwardshe concentrated mostly on the studies of spectraand diamonds through the diffraction andreflection of light in crystal beside others. A fewof his contribution will be of interest.

The Raman effect, the most pioneeringresult for which C.V. Raman was awarded theNoble Prize in 1930 was discovered in 1928.Interestingly three independent reports on thisphenomenon were published by Seshagiri Rao andC.V. Raman (1923), by K.R. Ramnath (1923), andby K.S. Krishnan (1925). ‘A New type ofsecondary radiation’ by Raman and Krishnan(Raman effect) came out as a note in Nature, dated31 March 1928, followed by anothercommunication by Raman to the same journalunder the title, ‘A change of wavelength in lightscattering’. Raman and his students succeeded insuperposing two light scatterings in transparentliquids and solids on which a new type ofmodified, rather very weak, florescence(scattering) was observed. Compton in 1927 wasgiven the Nobel Prize for the inelastic scatteringof X-ray photons (known as Compton effect).Towards the end of 1927 it suddenly appeared toRaman that their observation of moderate


scattering may be an optical analogue of theCompton effect, and is actually due to the rotationand vibration spectra of liquids and solidsoccurring in regions which could be visuallyobserved, or more comfortably withspectrographs, sensitive to the visible andultraviolet regions. He was convinced and sentimmediately the paper in his individual name toNature, and announced his discovery (which earnhim the Noble Prize) through a Press Conferencein 1928 held on February 28 to avoid any otherclaim. This is the reason that February 28 isrecognized as National Science Day in India.

Raman spectra of organic and inorganicsubstances was more clearly known from the studyof Raman and Krishnan. When the intensemercury lines in the region of 3650 to 4358 A°were used as incident ray, the spectogrums ofscattered radiations from benzene, toluene,pentane, ethyl & mythyl alcohols, water andcarbon tetrechloridem the result clearly establishedthat the frequency difference between theunmodified and modified lines is independent ofthe wavelength of the incident line. It alsoobserved that there is some agreement betweenthe shift of frequency of the modified lines withcertain characteristics of infrared frequencies ofthe molecule. With a single Raman spectrogramsit became possible to get all the infraredfrequencies of the molecule much more accuratelythan the infrared spectrometer. The study of theRaman spectra in liquids was far extended byRaman’s colleagues—S. Bagavantam, S.Vekateswaran, P. Krishnamurthi and others. It putthe theory of Raman effect to see deeper for itsfurther use in physical studies. Origin of wings inthe spectrum of the scattered light in liquids andalso of very low frequency lines found in crystalsare attributed to the hindered rotation of themolecules in the liquid and to the flexuraloscillation in the solid. The discrete lines whenmelted are changed into wings which becomebroader with the rising temperature. The influence

of symmetry of the crystal on the polarizationcharacters of the Raman lines have also beenwidely investigated by others.

The Theory of Diffraction of Light byultrasonic waves is another very important areainvestigated by Raman and his colleagues.According to them, the light in passing throughthe field of ultrasonic waves suffers changes ofphase in proportion to the amplitudes of the soundwaves. Various results like, effect of obliqueincidence, diffraction by superimposed waves,periodic visibility of the diffraction effects and soon, have been worked out, and effort was madefor quantitative explanations. Attempt was madeto determine the ultrasonic velocities in hundredsof organic liquids, and to study the dispersion ofvelocities in the acoustic spectrum. It was alsoobserved that the diffracted light has a frequencydifferent from the incident light, and the frequencydifference being equal to that sound waves. Thiseffect, though remains undetected with ultrasonicwaves, could be demonstrated with hypersonicwaves. These waves reflect the light waves,resulting in a change of frequency as in theDoppler effect. When two frequencies aresymmetrically displaced on either side of theincident frequency, the unmodified central lineindicate the presence of molecular cluster. Studiesmade on the frequency shifts have made it possibleto calculate the velocities of the supersonic waves.It was also observed that the hypersonic velocityin case of highly viscous liquids such as glycerineis appreciably higher than the sonic and ultrasonicvelocities, showing that such liquids exhibitappreciable rigidity at these high frequencies andpass over into solid state.

Crystal physics is related to the physicaland magnetic properties of crystals. Raman alongwith Krishnan studied the magnetic anisotropy ofcrystalline nitrate and carbonates, magneticbehavior of organic crystals relating to crystalstructure. Atomic vibrations in crystals was


considered another very important area. Thevibration spectrum of a crystal lattice consists ofa finite number of discrete frequencies, the modesof vibrations corresponding to these frequenciesbeing such that equivalent atoms in neighbouringcells in the lattice vibrate either in the same or inopposite phases. The results have been workedout for a number of crystals having simplestructures and as to their number of characteristicfrequencies. These are verified by Raman spectraby using a technique of special radiations of thequartz mercury lamp. This has resulted in thestudies of large number of crystals thoroughly like,calcite, quartz, barites, gypsum, topaz, diamondand so on. The results on diamond deserve specialmention, since the lines in this case have shownto remain sharp even under very high dispersionbecause of vibration frequencies being highlymonochromatic. The atomic vibration techniquein crystals has also been used to calculate thespecific heat and thermal expansion of a numberof crystals.

For obtaining dynamic of reflections incrystals, interesting technique was applied byRaman and his colleagues. Change of frequencywas noticed when the infra-red vibrations incrystal interacts with visible or ultraviolet light inthe scattered light. Change of frequency was alsonoticed for lattice vibrations in X-rays. The changeof frequency of the X-rays, though found verysmall to be determined, but the interaction of X-rays with crystal lattice results in a tilting of thereflecting planes of the crystal, and helped to geta new dynamic reflections in directions away fromthe Laue reflections. Such dynamic reflectionswere obtained for large variety of crystals. Theinvestigations with diamond support the theorywell. Whether the extra reflections are due to theinfra-red vibrations causing sharpness andspectacular nature and position of the reflectionshas been partly verified and accounted for.

Structure of Diamond was another areain which Raman took active interest. Raman

initiated a general discussion on the structure andproperties of diamond and dwelt on the crystalsymmetry and structure of diamond. Bagavantamstudied the normal oscillation of diamond-structure and calculated the elastic constant,G.N.Ramachandran took the X-ray topographs,determined the crystal structure and explained thenature of origin of laminations in diamond crystals.Raman and his other collaborators studied thelattice structure which gave the correctinterpretation of the vibration frequency 1332cm-1. Raman had a huge collection of diamonds,and from investigations it was found that thediamonds show large variations in its propertiesfrom one specimen to another, which wasattributed to inherent variations in its structure andnot due to the presence of any extraneousimpurities. He found that the internal structure ofdiamond is based on two interpenetrating facecentered lattices of carbon atoms. According tohim, these tetrahedral (solid figure enclosed byfour triangles) can point either way, so that thereare 2×2 or four possible forms of diamond, two ofwhich have tetrahedral and the other twooctahedral symmetry. In actual specimen, thesefour structures can occur side by side orintermingled with each other. It is the variationsin the nature and extent of the interpenetrationsof the different structures that gives rise to thevariations in the physical properties of diamonds.Experimental verifications are now being putforward that there are actually four varieties ofdiamonds.

Raman left a permanent stamp in thehistory of science in India as a great experimentalscientist a theorist of great order, and a man ofmagnified personality with full of vanity. He madea world of his own, and could be compared to thenucleus of an atom around which his collaboratorsused to move like electrons in specified orbits.He was possibly one of the best scientists that Indiahas ever produced.


6.3. Meghnad Saha

Meghnad Saha wasborn on 6 October 1893 ina village Seoratali indistrict Dacca, now in EastPakistan. He was the fifthson of his father who had asmall shop, M eghnad hadhis Entrane & Intermediatefrom Dacca, B.Sc (MathHons) and MSc (AppliedMathematics) from Presidency College, Calcutta.He had a brilliant career standing second in orderof merit while the first position was to his lifelongfriend S N Bose. In 1917, he, along with S N Bose,joined Department of Physics, Calcutta University,as lecturer. (About a year later C.V. Raman joinedthe Department as Palit Professor of Physics). Sahaworked in the field of electromagnetic theory andradiation pressure for which he was awarded D.Scdegree in 2018 from the same university. In 1920he went to England, came back in to join theCalcutta University as Khaira Professor ofPhysics, but took up the Professorship of Physicsalong with headship in the university of Allahabadin 1923 and remained there for 15 years. In 1927he was elected FRS by the Royal Society ofLondon. In 1938 he came back to CalcuttaUniversity as Palit Professor of Physics andremained there till his retirement in 1952.

From 1953 he served as Director of theLaboratories of Associations of the Institute ofNuclear Physics till to the time of his death in1956. His service to society as General Presidentof the Indian Science Congress Association,President of the Asiatic Society (Bengal),President of the Asiatic Society, Science & Cultureas editor, CSIR, University EducationCommission, Member of Indian Parliament (1951)and to many other positions made him very specialin the planning of Indian Science. However, hisresearch contributions in the area of physicalscience may be considered in phases.

1917-1922: Focussed on Maxwell’s stresses,pressure of light, dynamics of electron, radiationpressure and problems of the solar atmosphere,spectrum of hydrogen, ionization in the stellaratmosphere, elements in the sun, problems of novaacquila III, Ionization in the stellar atmosphere,stellar spectra, H- and K- lines of calcium in stellaratmosphere, Ionization of gases by heat; [majorareas, papers published independently or withcollaborators, S. Chakravarty, S.N.Bose & P.Gunther];

1923-1938 (at Allahabad): Worked on physicalproperties of elements at higher temperatures,thermal ionization, Influence of radiation onionization equilibrium, phase rule and itsapplication to problems of luminescence andionization of gases, spectrum of Si+ (once ionizedsilicon), absolute value of entropy, entropy ofradiation, radiation on ionization equilibrium,nitrogen in the sun, spectrum of neon & nebulium,spectrum of solar corona, negatively modifiedscattering, statistical mechanics, spin of proton,absorption spectra of saturated chlorides, complexX-ray characteristics spectra, β-ray activities ofradioactive bodies, upper atmosphere, stratospheresolar observatory, ultraviolet sunlight on the upperatmosphere, ionization of upper atmosphere;[papers published independently and/ or withcollaborators—N K Sur, R K Sur, K Majumder,B B Ray, P K Kichlu, D S Kothari, R C Majumder,A C Banerjee, S C Deb, A K Datta, S Bhargava,L S Mathur, R N Rai and others);

1939- 1956 (at Calcutta): Electromagnetic wavesin the atmosphere, structure of atomic nuclei,theory of solar corona, nuclear energetic and β-activity, radio waves from sun and stars,micro-waves of radio frequency range from sun,vertical propagation of electromagnetic waves;[papers published independently, or withcollaborators—S C Sircar, D Basu, A K Saha,B D Nagchaudhury, B K Banerjee].

In the first phase of his research Saha tookinterest on Harvard classification of stellar

Fig. 5. Meghnad Saha(1893-1956)


spectra and theory of ionization, He went toEngland by the end 1919 spent considerable timewith A. Fowler of the Imperial College whom heaccepted as his mentor. Then he went to Germany,Switzerland, and tried to contact Mount Wilsonand other observatories for spectroscopic data. Hiswork on ionization of course was recognized bythe Americal astrophysicists, H.N. Russel andothers. After his return he joined AllahabadUniversity as professor and focused his attentionto entropy and other problems, including nuclearphysics. In the third phase his interest was devotedto installation of cyclotron, institute of nuclearphysics and other projects in Calcutta. A few ofhis contributions will be of interest.

Thermal Ionization is Saha’s one of thegreatest contributions. The theory of high-temperature ionization and its application to stellarspectra has been well accepted and recognized.The ionization theory was formulated by Sahaworking by himself in Calcutta (as reported byProfessor D.S. Kothari). During his work with thespectra in the sun and stellar bodies, Saha couldnot identify the spectra of elements known in theearth, and also not otherwise. In the spectrum ofthe sun’s chromospheres, as well as during totalsolar eclipses, certain puzzling facts wereobserved, i.e. the H- and K- lines of calcium werefound much higher in the sun’s atmosphere thanthe corresponding lines of the lighter elements likehydrogen, helium or sodium. This fact waspuzzling and created confusion. Saha estimatedthe quantity of energy liberated when the normalcalcium atom (in vapour state) has lost an electronin ionized state, for he knew :

Ca = Ca+ + e – ε, where Ca= normal atomof calcium in vapour state (1 gm of atomis considered), Ca –+ = an atom which haslost one electron, ε= quantity of energyliberated;

He calculated the ‘reaction isobarequation’, taking into account the total pressure

and temperature, the quantity of the Ca atomionized, and the classical constant as perSackur-Tetrode-Stern relation. On his ionizationformula, Saha and his students (N.K. Sur, K.Majumdar) carried out several experimentalinvestigations at Allahabad later. This resultedverification of ionization of gases by heat, physicalproperties of elements at high temperature,experimental test of thermal ionization ofelements.

Entropy of the law of classicalthermodynamics was of interest to Saha and hiscolleagues. Of the two laws, first speaking on theconservation of energy, and the secondestablishing a direction in time by defining aquantity, called entropy, that increases in all realphysical processes. In fact, entropy was definedas a measure of the degree of disorder or as thetendency in any physical system towardsbreakdown. The effect of increased entropyindicates that a physical system evolves from astate of relative order to one of disorder, and withthis disorder there is increased complexity. It wasnoted that the changes of entropy can only becalculated for a reversible process. For this systemit was defined as the ratio of the amount of heattaken up to the absolute temperature at which theheat is absorbed. The total entropy of a systemmust either increase (irreversible process) orremain constant (reversible process).The totalentropy of the universe is therefore increasingtowards a maximum, corresponding to completedisorder of the particles in it (isolated system). Incollaboration with N K Sur, he worked not onlythe absolute value of entropy but also tried tocalculate the entropy of radiation. F C Auluck ofDelhi University worked on the entropy of Fermi-Dirac gas.

Nuclear physics is another area Saha gotinterested in Allahabad. After Chadwick’sdiscovery of neutron in 1932, Saha along with hisstudent D.S.Kothari thought that neutrons couldbe smuggled more easily into the nucleus of the


atom than the proton or alpha particle to inducenuclear reactions in all atoms. They vehementlytried for a donor who could gift a small amount (1gm) of radium for research work but remainedunsuccessful. At the same time Fermi’s work onneutron-induced-reactions came out, for hereceived about a gram of radium from the ItalianGovernment for their successful experiment. Fromthe time of his visit to Europe and USA in 1936,he developed an idea of having an Atomic EnergyProgram for peaceful utilization and welfare ofthe society. After his return to Calcutta University,he wanted to establish a Cyclotron at the CalcuttaUniversity, for which his student B.D. NagChaudhuri was deputed to Berkeley University forproper training. A Cyclotron was installed at theUniversity and Saha felt very happy when nuclearfission by splitting a heavy atomic nucleus (e.g.,uranium) into two equal parts, at the same timeemitting nucleus and releasing very large amountof nuclear energy, was started in 1939. This gavethe impetus to establish the Institute of NuclearPhysics in Calcutta. The helplessness for nothaving 1 gm of radium before came out at theopening session of the Institute of Nuclear Physicsin Calcutta inaugurated by Marie Irene Joliot Curie(1957).

A Stratographic Observatory wasvisualized by Saha in 1936 while he was attendinga Summer School in Astrophysics at Harvard. Hegave his impression what could be seen above theozone layer and how this observatory will help inthis investigations. How Saha’s dream came trueand predictions verified has been elaborated byHarold Shapley in his Saha’s ’Obituary’ publishedin the Journal of the Asiatic Society (1957).

Dirac-Saha Equation in 1949 was hismasterly re-derivation of Dirac’s quantizationcondition for magnetic monopole. Magneticmonopole is a hypothetical unit of magnetic chargeanalogous to electric charge. No evidence has beenfound for the existence of a separate magneticpole, for they are always found in pairs. Saha

estimated from classical consideration the massof magnetic monopole to be 2.54 times that of aneutron (approx. 2.5 Gev). The verification of thisresult will be tested when magnetic poles aredetected.

S. Rosseland, in Theoretical Astrophysics(Oxford University Press, 1939, Introduction)writes about Saha’s contribution thus,‘ It was theIndian physicist Meghnad Saha who (1920) firstattempted to develop a consistent theory of thespectral sequence of the stars from the point ofview of the atomic theory. The impetus given toastrophysics by Saha’s work can scarcely beoverestimated, as nearly all later progress in thisfield has been influenced by it and much of thesubstantial work has the character of refinementsof Saha’s ideas’. J V Narlikar in his book ScientificEdges (Penguine Books, 2003, p.127) writes,‘Meghnad Saha’s ionization (c. 1920) whichopened the door to stellar astrophysics was one ofthe top ten achievements of 20th century Indiancontribution in science and could be consideredin the Noble Prize class’.

Saha’s role in building a large number ofscientific organizations, e.g., Indian NationalScience Academy, CSIR institutes, Saha Instituteof Nuclear Physics, a prestigious bulletin likeScience and Culture, are also some of his positiveinitiatives. Beside being a great scientist, he wasa true nationalist and a spirit behind building ofmodern India with science and scientific temper.

6.4. S N Bose

Satyendra Nath Bosewas born in January 1, 1894 inCalcutta. His father, SurendraNath Bose, was originally fromthe district of Nadia, anaccountant in East IndianRailway. He was the first childof his father followed by sixother sisters. He had a brilliantcareer standing first in order in

Fig. 6. S N Bose(1894-1974)


his B.Sc. (Honours in Mathematics) and MSc(Mixed Mathematics). He was appointed lecturerin Physics of the Calcutta University in 1917, leftfor Dacca University and joined it as Reader inPhysics in 1921.

In 1945 he came back to CalcuttaUniversity as Ghosh Professor of Physics andDean of Faculty of Science. He obtained honoriscausa ( honorary D.Sc. degrees) from manyuniversities in India (Calcutta, Jadavpur,Allahabad, ISI Calcutta and Delhi), GeneralPresident of Indian Science Congress (1945-48),President of National Institute of Sciences in India(1949-50),became Padma Vibhusan (1954), FRS(1958), Vice-Chancellor of VisvabharatiUniversity & National Professor (1958-74). Thenumber of his research articles are hardly 25 (fordetails, vide INSA Biographical Memoires of theFellows, Vol.7, 59-79):

1917-1920: Worked on finite volume of moleculesand equation of state, stress equation ofequilibrium, deduction of Rydberg’s law fromquantum theory of spectral mission [paperspublished independently and/or with collaboratorM N Saha]

1921-1944 (at Dacca): Planck’s law andhypothesis of light quanta (first paper to Einstein),Thermal equilibrium between radiation and matterand a different law of probability for elementaryparticles (second paper to Einstein),momentcoefficient of D2 statistics, progress in nuclearphysics, anomalous dielectric constant of artificialionosphere, electromagnetic waves in theionosphere, studies of Lorentz group of equationsand solutions of the equation : ∆2ϕ – (∂2ϕ/c2∂t2) =- 4 πρ (x,y,z,t), note on Dirac equations and theZeemann effect [papers published independentlyand /or with collaborators, S R Khastgir, S C Kar,P K Datta, K Basu].

1945-1956 (at Calcutta): Integral equationrelating to hydrogen atom, extraction ofgermanium from sphalerite (collected from

Nepal), affine connection in Einstein’s new unitaryfield theory, Albert Einstein; [9 articles publishedindependently and /or with collaborators, R.K.Dutta, B.C. Dutta, J. Sharma].

S.N. Bose was brilliant as a studentstanding first in all most all the exams; among hiscolleagues a few distinguished names are:Maghnad Saha, Nikhil Ranjan Sen, Jnan ChandraGhosh and others. He was a man of simple habits,deep thinking, and a great intellectual. To beginhis career, he translated Einstein’s paper on theoryon relativity from German language into Englishalong with Saha. His article to Einstein, printedwith Einestein’s rejoinder, is a landmark in history.Bose’s paper on radiation theory and other topicsare equally brilliant. His trip to Paris during 1924-25, working with Madame Curie, Maurice deBrooglie, meeting in Berlin with Einstein set thetone in his life. An account of his originality hasbeen given by many of his colleagues includingMehra and Rechenberg (1982), Mukunda(1994),Ghosh (2005), and many others. However, someof his contributions will be of interest:

Radiation and the Ultra-VioletCatastrophe was the pet subject of Bose. Whilehe was giving his lectures in the university ofDacca, he reiterated that the contemporary theoryon radiation was inadequate because it predictedresults not in accordance with the experimentalresults. He predicted that Maxwell-Boltzmanndistribution would not be true for microscopicparticles where fluctuation due to Heisenberg’suncertainty principle will be significant. Thus hestressed the probability of finding particles in the‘phase space made state’ having volumeassociating the distinct position and momentumof the particle.

Boson, Bose- Einstein Statistics & Bose-Einstein Condensate are best known when Bosein early 1920 prepared a paper on, ‘Planck’s lawand hypothesis of light quanta’, and made a requestto Einstein to translate it into German for its


publication. It came out in Zeitschrift fur Physik(1924) with Einstein’s German translation withhis own rejoinder. Bose’s main interpretation wasthat since photons are indistinguishable from eachother, one cannot treat any two photons havingequal energy as being two distinct identifiablephotons. According to him, all particles in theuniverse whether elementary or composite, havebeen found to belong to one or two classes, viz,one which exhibit integral spin, named as ‘Bosons’by Dirac, and the other having half- integral spin,known as ‘Fermions’ by Pauli. No exceptions tothis rule have been found so far, provided allpossible degrees of freedom are taken into account.Bose’s explanation is known as Bose-EinsteinStatistics’.The result derived by Bose laid thefoundation of ‘Quantum Statistics’. Einsteincombined Bose’s theory and De Brogli’s hypothsis(Ph.D thesis after it is examined by him) on thequantum theory of gases. This led to the predictionof existence of phenomenon which became knownas Bose-Einstein condensate, a dense collectionof bosons (particle with integer spin), which wasdemonstrated to exist by experiment in 1995).Schrodinger later said that the discovery of wavemechanics and the Schrodinger equation waslargely influenced by this paper. It is BoseStatistics, Bose condensate and Boson whichemphasize the impact of Bose’s work. Bose wasnot a Nobel Laureate, but In this context thereference of the press release of 2001 Noble Prizein Physics will be of interest. It says,

‘This year’s Noble Laureates havesucceeded in discovering a new state ofmatter, the Bose-Einstein condensate(BEC). In 1924 the Indian physicist Bosemade important theoretical calculationsregarding light particles. He sent hisresults to Einstein who extended thetheory to certain type of atom. Einsteinpredicted that if a gas of such atoms werecooled to a very low temperature all theatoms would suddenly gather in thelowest possible energy state. The processis similar to when drops of liquid form

from a gas, hence the term condensation.Seventy years were to pass before thisyear’s Noble Laureates, in 1995,succeeded in achieving this extreme stateof matter’.

Radio- waves and Wave-equation are fewsuch areas in which Bose was also interested. Heinvestigated the problem of total reflection ofradio-waves in the ionosphere, by solving theclassical Lorentz equation by the method ofcharacteristics. From the general scheme he foundfour different possible conditions for the totalreflection of radio-waves only under different setsof simplifying conditions. He published anotherpaper on Lorentz group in which a fourdimensional transformations was decomposed intotwo factors which led to the spinors from algebraicconsiderations. He along with S.C. Kar gave acomplete solution second degree differentialequation involving four-dimensional space-timecontinuum; a similar equation has been found tobe used by Bhabha during his lecture on problemsof cosmic rays in the Calcutta UniversityDepartment of Mathematics (1941). Bose alongwith K.M. Bose gave an exact solution of Dirac’sequation for hydrogenic atom in a magnetic field(1943), and deduced an integral equation forSchrodinger’s wave –equation for hydrogen atomin the momentum space and discussed the physicalproblems from the integral equation.

Bose’s contribution have been relativelyfew but remarkable. His contributions in physicalscience and mathematics got international ovation.Over and above, he was founder of Bangiya VijnanParishad and his main aim at the fag end of hiscareer was to popularize science in Bengali. Hewas a great lover of arts, fond of instrumentalmusic (seldom missed an art or painting exhibitionor musical concert, specially of classical type),and himself played on the Esraj like a master. Heis a genre of his own and known for inner sparksin his thoughts.


6.5. S K Mitra

Sisir Kumar Mitra, theson of Joykrishna Mitra wasborn in Calcutta. His fatherwas originally from Konnagar,Hoogly, came to Calcutta forthe medical education of hiswife in the Campbell MedicalSchool, and shifted toBhagalpur, as his wife got anappointment in the LadyDufferin Hospital at Bhagalpur after obtaining herdegree. Young Sisir had his school education fromBhagalpur, B.Sc. and M.Sc. degrees fromPresidency College, Calcutta. He joined theCalcutta University as lecturer of Physics in 1916and obtained D.Sc. degree of the University in1919. From 1920-23 he stayed in Paris andobtained another doctorate degree from theuniversity of Sorbonne. He then returned toCalcutta University and joined as Khaira Professorin Physics in 1923.

His associations with Wireless Laboratory,Ionosphere Research school, HaringhataIonosphere Field Station at Calcutta, UpperAtmosphere and Space exploration with artificialSatellites made many significant contributions. Hebecame Chairman of the Radio Researchcommittee of CSIR (1943-48), President of theAsiatic Society of Bengal (1951-52), President ofthe National Institute of Sciences in India (1956-58). He got FRS from Royal Society London(1958), Padmabhusan (1962), National ResearchProfessor in Physics by the Government of India.

1918-1923: Worked on illumination curves inoblique diffraction, Sommerfeld’s problem ofdiffraction by a semi-conductor screen, diffractionby apertures with curvilinear boundaries,diffraction figures observed in a heliometer, radiowaves, electric oscillations (papers publishedindependently).

1924-1947: Beats by high frequency interruptionof light, refraction of light by electrons, periodic

classification of elements, resistance of thermionicvalves at high frequencies, spontaneousoscillations in low pressure discharge, recordingwireless echoes at the transmitting station, effectof solar eclipse on the atmosphere, study of theupper ionized atmosphere in Bengal by wirelessechoes, earthquakes, effect of a meteoric showerson the ionosphere, transmission of radio wavesround the earth, knowledge of ionosphere,dielectric, absorbing layer and the ionosphere atlow heights, magnetic double refraction of ionizedair, need for a radio research board in India,wireless echoes from low heights, radio wavesfrom middle atmosphere, distribution of gases andtheir pressures in the upper atmosphere, E-layerof the ionosphere, ozone-sphere and E-layer ofionosphere, ultraviolet light theory of aurora andmagnetic disturbances, atomic oxygen elasticcollision with electrons and the region of Fabsorption, zodiacal light and light of the nightsky, active nitrogen and N2 ions, after-glowbrightness of active nitrogen, night-sky emissionand region F ionization, radar, auroral spectrum,geomagnetic control of region F2 of theionosphere, microwaves, the upper atmosphereand some unsolved problems; [papers publishedindependently and/or with collaborators, DBanerjee, H Rakshit, B C Sil, P Syam, B N Ghose,S S Banerjee, A C Ghosh, J N Bhar, S P Ghosh, AK Banerjee, B B Ray, S Das Sharma].

1948- 63: N2+ ions and some nitrogen after-glow

phenomena, active nitrogen in aurora, the UpperAtmosphere (2nd edition), thunderstorms andsporadic E ionization of ionosphere, aeronauticsand electronics, electronics in the service ofmedicine, upper atmosphere and space explorationwith artificial satellites, physics of the earth’s outerspace [published independently and/or withcollaborators, M R Kundu].

His foreign trips to Paris during 1920-23,working under Charles Fabri of the University ofSorbonne on a topic, ‘Determination ofWavelength in the region 2000-2300 A0 of the

Fig. 7. S.K. Mitra(1890-1963)


copper spectrum’ and training in ‘radio valvescircuits and radio communications in Gutton’slaboratory, Institute of Physics, University ofNancy were considered very useful for hisincreasing interest in upper atmosphere. In theIonospheric research, the technology of radiophysics and electronics played an important role,and in this field the works of S K Mitra, G RToshniwal and S R Khastagir are prominent.However, Mitra and his group studied the effectof solar eclipse on the ionosphere, measuredatmospheric height at Calcutta during Polar year,height of the absorbing layer, the C region andthe origin of E layer of the ionosphere, anomalousdielectric constant of artificial ionosphere, and theradio-wave propagation in ionosphere. Howeversome of his results are of interest:

Upper Atmosphere and the space beyondhundreds and thousands of kilometers above thesurface of the earth was of interest to Mitra Theperiod : 1925-35 was, according to Prof Mitra,was a difficult period for the ionosphere workersto go through the collections of many researchcentres, and publications made in the form ofreports and research papers on ionosphere. Whathe did, he collected all these details containingworld picture of ionosphere, which he presentedin his opening speech organized by NationalInstitute of Sciences in India in the year 1935,under the title, ‘Report on the Present State of ourknowledge on Ionosphere’. The book in itsenhanced form was published by the AsiaticSociety in 1947, of which 2000 copies of the bookwas sold quickly worldwide. Another revisededition came out in 1952 followed by Russiantranslation.. The knowledge has been greatlyenhanced with the help of artificial satellites. Thelaunching of artificial satellites has actually beenstarted with the program of InternationalGeophysical year (1957 1st July to 1958 31st

December).

Systematic efforts have now been madeto place earth satellites in orbit, moon rockets and

other types of satellites by the Russian, American,Chinese and other developing countries, may bejust out of sheer curiosity, but ultimate challengeof manned satellite into space was as to how toovercome the earth’s gravity. Earlier there wereonly two widows to the screening of theatmosphere through wide range of electromagneticmeasures, either corresponding to light waves orthrough radio waves. But the satellite program hasmade it possible to collect reliable data of thephysical conditions in inaccessible remote regionsof the atmosphere and outer space, specially inthe area of radio communication and meteorology.The earth-satellites (Explorer I, IV, VI, VII,;Vanguard I & II, Sputnik II & III, Discoverer VII& VIII), and Moon rockets (Pioneer I, III, & IV;Lunik I, II & III), launched between1958 and 1959supplied valuable data in this connection.

Density, Pressure, TemperatureDistribution at some selected heights in UpperAtmosphere were areas selected by Mitra forinvestigation. In this context he developed a modelconstructed in 1952 based on certain assumptions(Table 1). The density distribution is now generallycomputed from the orbital data of the satellite. Theorbit of the satellite is not fixed, and changescontinually, firstly due to drag effect specially atits perigee when it passes through comparativelydense atmosphere, and secondly due to irregulargravitational pull of the earth differingconsiderably the ideal central pull of a sphericalearth. The geomagnetic disturbance is alsoassociated with with solar corpuscular emission,and the upper atmosphere density is effected by

Table 1. S.K. Mitra model (1952)

Height Density Pressure Temperature(km) (gm/cm3) (mm of Hg) (0K)

800 3.67 × 10-17 2.13 × 10-10 3040500 7.00 × 10-16 2.25 × 10-2 1840300 2.11 × 10-14 3.83 × 10-8 1040110 4.98 × 10-10 2.70 × 10-4 270100 1.74 × 10-9 1.00 × 10-3 240


heating by heating due to absorption of suchemission. Revised data based on high altituderocket and satellite data has been suggested byA.P. Mitra and S.B. Mathur in 1959 (Table 2).Thedata at 800 km height is significantly different inboth the tables.

Ionosphere studies by him have indicatedthat while stratosphere extends approximately 11km from the surface of the earth, the Ionosphereextends to much greater heights and merges withthe interstellar gas at a distance of several tens ofearth’s radius. It produces a number of effects onthe radio signals transmitted through it from a firstmoving satellite. To estimate the electronconcentration in the ionosphere at great height,all the effects detected on the radio signals andthe positional data of the satellite are taken intoaccount. These measurements are of considerableimportance, as the transmitter located on theground do not catch any electron concentration inregions above the level of maximum ionizationof the F2 layer (the region between 300 km and500 km). The ionospheric effects on satellite radiosignals are mainly of three types, viz., Faradayfading effect (because of changes of the plane ofpolarization as the satellite changes its positiondue to rotation), Doppler effect (shift in frequencyof the transmitted signal due to motion of thesatellite) and Refraction effect (due to radio-risingand radio-setting of satellite, when the bending ofthe radio waves entering the atmospheric layer isaway from the normal, refractive index being lessthan unity). The distribution of the Electronconcentration at different heights are given alongwith densities of the neutral particles (Table 3).

Table 2. A.P. M itra and S.B. M athur model (based onrocket and satellite data, 1959)

Height Density Pressure Temperature(km) (gm/cm3) (mm of Hg) (0K)

800 6.00 × 10-17 4.81 × 10-10 2068500 1.54 × 10-15 9.46 × 10-9 1591300 4.97 × 10-14 1.85 × 10-7 1023130 2.74 × 10-11 3.46 × 10-5 462

Table 3. Height distribution of electrons (deduced fromradio-rising and radio-setting of the satellite)

Altitude Electron Density of neutral(km) concentration particles (N per cm3)

(N per cm3)

3,100 1 × 102 < 12,450 1 × 103 201,800 1 × 104 2 × 103

1,150 1 × 105 2 × 105

600 7 × 105 1 × 107

400 1.4 × 106 6 × 108

320 1.8 × 106 ......

200 1 × 105 ......

The figure in the last column—density ofneutral particles at great heights—are obtainedfrom consideration of the life time of free electronin these regions. It is the time that elapses betweenthe production of the electron by ionization andits disappearance by recombination, which is inthe order 105 to 106 seconds or more in over 24hours. Taking this into account, the density is 107

at height 600 km (Table 3) is comparable with thedensity value 106 at 800 km (Table 1).

Corpuscular Radiation Belt was believedto be a zone whose outer belt contains streams ofcharged particles emitted from the Sun and theinner belt contains possibly the inner ray neutronsproduced in the atmosphere. The solar originhypothesis of the outer radiation belt explains along standing difficulty of the auroras. For thesolar corpuscles, if they are to reach the aurorallatitudes (with in 250 of the magnetic poles), theelectron or proton speed will not be able to ionizethe atmosphere at the height of the most frequentoccurrence of aurora (round 100 km), then how?There are many opinions, not discussed here. Asregards neutron hypothesis of the inner belt it isassumed that the particles have their origin in theneutrons produced by interaction of cosmic rayswith atmospheric particles.

Cosmic ray data in the atmosphere asobtained from the satellite radio-telemetered from


Sputnik II observations were also analyzed byMitra. The latitude and longitude dependence ofthe cosmic rays showed that the lines of equalintensity do not follow the geomagnetic parallels.It confirmed the view that the cosmic ray equatordoes not coincide with the geomagnetic equator.It also came out that above 200 km the intensityof the cosmic rays increased with height. At 700km it was about 40% more than that at 200 km.The increase with height was assessed for tworeasons—decrease of intensity of earth’s magneticfield with height, and reduction of the screeningeffect of more particles from the earth reachingthe satellite. Fluctuations on intensity was alsoobserved, the reason of which was not clear.Beyond 10 and 17 earth-radii (the outer most pointof the observation), the counting rate of the maincounter appeared to reach an asymptotic value,and the counter gave the value of 3.2 cm2/secbetween interplanetary distance at this height.

Mitra was laborious, extremelymethodical, known for his devotion to duty,precision and perfection. He was a lover of order,cleanliness and beauty besides being a goodscientist.

6.6. H J Bhabha

Homi JehangirBhabha, son of Jeehangir HBhaba, M.A.(Oxon), Barrister-at-Law, was born on 30October, 1909. He had hiseducation at the Cathedral andJohn Connon Schools,Elphinstone College, andInstitute of Science inBombay. From his childhoodhe had developed a keen sense and love for music,recorded symphonics, concertos, quartets andsonatas of Beethoven and Mozart and others, forhis aunt (wife of J.N. Tata) who lived across theroad had a huge collection of records. In 1927 hejoined Caius College in Cambridge, obtained

Tripose in mechanical sciences in June 1930, andbecame a research student in theoretical physics.During his research tenure in 1932 in theCavendish Laboratory, he was exposed to theexperiments on the existence of neutron,transmutation of light elements by high-speedprotons, cloud chamber photographs of theproduction of electron pairs and showers bygamma radiation. In 1939 Bhabha came back andjoined Indian Institute of Science, Bangalore asReader in Physics and stayed there for five years.

He became the first Director of TataInstitute of Fundamental Research (TIFR), andwas appointed Chairman of the Atomic EnergyCommission in August 1948. Subsequently theBhabha Atomic Research Centre (original name-Atomic Energy Establishment, Trombay) foratomic research was founded on 12 January 1967.Bhabha became FRS in 1941, Padma Bhusan in1954, Adam’s prize and many other prizes for hiswork on elementary particles. He received honoriscausa, i.e., honorary doctorate degree from manyuniversities in India and Abroad. Bhabhapublished about 82 research papers (VideBiographical Memoires of the Fellows of theNational Institute of Sciences in India, Vol. 2,1970, pp.78-97).

1933-1939: Concentrated on the annihilation offast positrons by electrons in the K-shell, creationof electron pairs, electron-positron scattering,passage of first electron through the matter, waveequation in conformal space, passage of fastelectrons and the theory of cosmic showers,negative protons in cosmic radiation, proton-neutron exchange interactions, penetratingcomponents of cosmic radiation, heavy electronsand nuclear forces, theory of mesotron(meson),bursts and the spin of the meson, classicaltheory of electrons and mesons (publishedindependently with collaborators, H R Hulme, WHettler, H Carmechel, C N Chou).

1940-1960: Classical theory of spinning particles,point dipoles, spinning particles in Maxwell’s

Fig. 8. H.J. Bhabha(1909-1966)


field, scattering of charged meson and spinningparticles in meson field, classical and quantumtheories of neutral meson, protons of doublecharge and the scattering of meson, particles ofhalf spin and Compton effect, radiation reactionrelating to scattering phenomena, cascade theorywith collision loss, separation of electronic andnon-electronic components of cosmic radiation,relativistic wave equations for the proton, mesonintensity in the sub- stratosphere, latitude effectfor mesons, equation of motions in point particles,relativistic wave equations of spin 3/2, productionof mesons and localization of field energy, heavymesons of a solid emulsion block; (collaborators,B S M Rao, D Basu, S K Chakravarty, HarishChandra, R R Daniel, H J Talor, J R Heeramaneck,A Ramakrishnan, N B Prasad, W B Lewis);

1961-1966: Atomic power in India, atomic energyin Indian economy and underdeveloped countries;(Collaborator, M. Dayal).

Cosmic ray was one area on which Bhabhashowed wide interest. From the time he had beenstudent at Gonville and Caius College, Cambridge,UK, he studied theoretical physics under N.F. Mottand P.A.M. Dirac, and his paper on cosmic ray,‘Absorption of cosmic radiation’ came out fromW. Pauli’s laboratory at Zurich in 1933. His paperson cosmic radiation, cosmic showers, electronshowers on cosmic rays, and penetratingcomponents of cosmic radiation were quicklypublished before he came back to India. Here hecollaborated with S.K. Chakravarty and carriedout a number of theoretical studies with cascadetheory of electronic showers with collision loss,nature of primary cosmic rays and the photonsassociated with cascade theory. According toM.G.K. Menon, the second Director of TIFR, theperiod 1940-45 in IISc was extremely fruitful toBhabha. In 1945 he became the Director of TIFR.His interaction with the stalwarts like, WolfgangPauli and Enrico Fermi in Rome, and Neils Bohrin Copenhagen helped him to plan his researchon cosmic rays including its interaction with

matter. This led to the discovery of electron pairs,muons and so on.

Bhabha Scattering gained internationalrecognition after Bhabha established a correctexpression for probability of electron relating topositron scattering and meaningful method formeasuring the cross section. In this context, hiswork on Compton scattering on the reduction ofenergy of a photon in its interaction with a freeelectron, R-process, and nuclear physics are quitenoteworthy.

Absorption of Cosmic Radiation featuresand electron showering production in cosmic rayswere areas of concern to Bhabha, who madeexperiments and offered suitable explanation. In1936 he published two papers on ‘The Passage ofFast Electron’ and the ‘Theory of CosmicShowers’, in which he used the theory howprimary cosmic rays from outer space interact withthe upper atmosphere to produce particlesobserved in the ground level. Bhabha and Heitlerthen made numerical estimate of the number ofelectrons in the Cascade process at differentaltitudes for different electron initiative energies.The Cascade process is actually used forseparation of isotopes. It consists of a series ofstages connected in such a way that that theseparation produced by one stage is multiplied inseveral stages. In a simple cascade method, theenriched fraction is fed to the succeeding stageand the depleted fraction to the preceding stage.The calculation made by Bhabha and his colleagueagreed with the experimental observation ofcosmic ray showers by Bruno Russi and PierreVictor Augar.

Nuclear Program was planned by Bhabhastage by stage. First Apsara (1 MW) was builtdesigned and built by Indian engineers. It wasmade for engineering experiments, material testingand isotope production. Second was CanadianIndian Reactor (40 MW) under Colombo plan toprocess monazite sands of Kerala beach and toseparate rare earths—thorium and phosphates,


thorium hydroxide and uranium fluoride and soon. His plan was power generation in three stages,from Thorium (rather than Uranium), total reserveof Thorium being rich to the tune of 500,000 tons;second the Plutonium obtained from the firstgeneration power station can be used in the secondgeneration of power station, designed to produceelectric power. The process will convert Thoriuminto U-233 or depleted Uranium into Plutoniumwith breeding gain. The second generation ofpower stations may be regarded as intermediatestep for breeder power station of third generationwhich will produce more U-233. Then they willbegin in the course of producing power.

Bhabha had a smart personality and was aman of great caliber, artist, having many otherqualities. Many of his contemporaries rememberhim for his sketch of Niels Bohr and piano playing,besides being a top class nuclear scientist.

6.7. S Chandrasekhar

Subramanyan Chandrasekhar was born inLahore on October 19,1910.His father settled inMadras in 1918 when hewas Deputy AccountantGeneral of NorthernRailways. Chandra wasnumber three in a familyof ten children (4 sonsand 6 daughters). Helearnt German languageduring his undergraduation in Presidency College, Madras, andshowed a great interest in science research throughhis articles on Pauli’s paper on quantummechanics, Compton scattering and New Statistics(published in Proceedings of the Royal Society,1929) in his student days. In 1930 he got aGovernment of India scholarship on therecommendation of the college Principal andadmitted the same year at Trinty College,Cambridge and discovered a critical limit of the

life of white dwarf star. In 1933 he received Ph.Don his thesis, ‘Distorted Polytropes’, FRS (1944)from Royal Society (London). Joined theuniversity of Chicago as an undergraduate studentin 1955, served its faculty till to the time of hisdeath in 1995. Received many prizes ofinternational repute, and won Nobel Prize forPhysics (1983) on the structure and evolution ofstars. Government of India honoured him withPadmavibhushan in 1968. His phase-wiseresearch work may be noted as under:

1930-1942: Chandrasekhar limit, white dwarfstars, stellar structure, stellar dynamics, statisticaltheory of stellar encounters; complex statisticalmechanical problems; [Vide his books on StellarStructure and Stellar Dynamics]

1943-49: Absorption and emission lines in stellarspectra, radiative equilibrium in stellaratmosphere, radiation field in the atmosphere,analysis of radiative transfer of stellar atmosphere,illumination and polarization of the sunlit sky,formulation of fundamental equations governingRayleigh’s problems and their solutions,systematic use of non-linear integral equations anda special class of such equations (Chandrasekhar’sX and Y functions) and their solutions, classicaltreatment of polarization of light, neutron transportand diffusion; [Vide his books on EllipsoidalFigures of Equilibrium, and Radiative Transfer]

1950-1960: Studies on quantum mechanics,electrodynamics & optics, mathematical theory ofrelativity, stability problems, and plasma physics;hydrodynamics and hydromagnetic stability,quantum theory of the negative ion of hydrogen,theory of turbulence, confirmation of thesetheories at a special laboratory at the universityof Chicago, formulation of stability theory usingvariation principles, (studies compiled in hisbooks, Plasma Physics, Hydrodynamics andHydromagnetic Stability);

1961-1995: mathematical theory of black holes,and colliding gravitational waves; [See his books,

Fig. 9. S. Chandrasekhar(1910-1995)


Mathematical Theory of Black Holes; Truth andBeauty].

Chandrasekhar got interested in the stateof matter in stellar interior, source of stellar energy,stellar models and the problems of white dwarfsand highly condensed stars, including estimationof maximum mass. His early work was concernedwith thermodynamics of the Compton effect withreference to the interior of the stars. As to theopacity coefficient of degenerate matters essentialfor the calculation of temperature of this type ofstars, Chandrasekhar, besides D.S. Kothari andR.C. Majumdar, has done wonderful work. Hispublications on physical state of matter andpressure in the interior of stars and also of theirconstitution were studied intensely by him. Someof his results will be of interest:

Theory of White Dwarf stars which arenot like other normal stars has been a major areaof interest to Chandra. These dwarfs are highly‘under-luminous’, much fainter, and are judgedon the basis of an average star of the same mass.A typical dwarf star is the companion of Siriuswhich has a mass equal to that of the Sun butwhose luminosity is only 0.003 times that of theSun, i.e. only 0.3 percent. In addition, white dwarfsare characterized by exceedingly high values ofmean density. Moreover, Sirius has mass equal tothat of the Sun and has a radius of approx. 20,000km, astonishingly small for such a great mass. Thisimplies a density of 61,000 gms/cm3, or just abouta ton/ inch3. But why the dwarfs are of such lowluminosity was still a matter of great theoreticalimportance. It was found that for a given effectivetemperature, the white dwarfs are much fainterthan a star on the main series, or in other words,to maintain the same luminosity, the white dwarfwill need a very much higher effective temperature(for much whiter) than the main series stars. Toget an answer, Chandra based his calculations onEinstein’s special theory of relativity and the newquantum mechanics, and found that if the mass ofthe star exceeded a certain critical mass,

expressible in terms of the fundamental atomicconstants, the star would not become a whitedwarf. For sufficiently large mass, specialrelativity comes in eventually and quantummechanical pressure cannot compete with thegravity nor with the classical thermal pressure. Astar will keep on contracting in this limit as itradiates away energy, and will eventually suffer aworse fate. It was admitted before that no radiationcould escape from a star if it contracted to lessthan its Schwarzschild radius. Such a state ofinvisibility is what we know as a black hole. Theimportance of this discovery is now firmlyestablished and well adopted by astronomers, inspite of initial objection and criticism by Sir ArthurStanley Eddington.

A maximum mass limit of white dwarfstars, Chandra suggested, as 1.44 solar masses,which is known as Chandrasekhar Limit. He saysthat a star becomes unstable before they reach thislimit. Or in other words, if the star mass is greaterthan 1.44 times the solar mass, the minimum masswhich must be exceeding for a star may ultimatelycollapse. While working on general relativisticproblems, it became clear to him that the starsmore massive than this limit might have exhaustedtheir nuclear fuel, could contract to much denserneutron star. Even though they have a similar butlarger mass limit, these massive stars couldcontract to Black holes, if they do not explodecompletely as supernova. Black hole is a regionon space-time from which gravity preventsanything including light from escaping. It isexpected to form when very massive stars collapseat the end of their cycle. After a Black hole isformed it continues to grow by absorbing massfrom its surroundings. The limit was calculatedby Chandrasekhar in 1930 during his voyage toCambridge from India. It took nearly three decadesbefore the full significance of the discovery ofBlack hole was recognized. Chandrasekhar limithas now entered the standard lexicon of physicsand astrophysics. His mathematical theory ofBlack hole was published in 1983.


Distribution and motion of stars was alsoa favourite area of Chandra. He calculated in detailthe factors responsible for their slowing down dueto gravitational drag of the neighbouring stars. Hisstudies on stellar structure and stellar dynamics(1932-42) established that that stars experiencedynamical friction and suffer from a systematictendency to be decelerated in the direction of themotion. This dynamical friction is one of theconsequences of the fluctuating force acting on astar due to the varying complexion of theneighbours. On stellar dynamics, he and hiscolleague, Von Neumann applied the statisticalanalysis of the stellar encounters. His treatise onrotating objects began to be appreciated after twodecades of its publication.

Stability in hydrodynamics andhydromagnetic problems was formulated verycomprehensively using variational principles ofmathematics. Starting with a discussion of theclassical Benard convection problem oftransferring of heat through a liquid or gas andsetting up a convection current, Chandrageneralizes it by including the effect of rotationof magnetic field, then extending it to theircombined effect, followed by discussion on theproblems of thermal stability in fluid spheres,spherical shells, stability of coquette flow andmore general flows between co-axial cylinders,jets and cylinders and some problems ofgravitational stability. His book on Hydrodynamicand Hydromagnetic Stabily (1961) is a masterpresentation in the field.

Chandrasekhar Number was discoveredwhen he was busy shorting out magneto-hydrodynamical problems (1961). For assessingfriction in fluid motion Mach number of the flowof fluid and Reynolds number for assessing thefriction in fluid motion were already popular.Turbulent flow was also decomposed into variouscomponents by Reynolds or Navier-Stokesequations or by direct numerical simulation. N.R.Sen and his student H.P. Majumdar gave solution

of equations for early stage of turbulence.Chandrasekhar, however, gave a numericalsolution of Heisenberg’s homogeneous isotropicturbulence exhibiting uniform propertiesthroughout in all directions. He has also used animportant dimensionless number for magneto-hydrodynamics, named as Chandrasekharnumber.

Chandra’s interest in classical physicalideas was renewed when he started writing acommentary on Newton’s Principia from modernperspectives in the fag end of his career andpublished it for common readers. Even his workon mathematical reasoning of the scattering oflight has drawn attention.. Chandra was anextremely methodical and talented teacher andresearcher who is an example for others.

Chandrasekhar was a great astrophysicistand much ahead of his time. He was a teacher inthe true sense, and made everything appearedsimpler through exhaustive and critical analysis.According to Martin Schwarzchild (the well-known astrophysicist), ‘There is not one field thathe’s worked in, where we are now daily usingsome of his results’. In his Noble Lecture (1983),Chandra himself emphasized in the concludingremark of his Nobel Lecture about Beauty, Truthand Symmetry in the Universe, leading us intothe realms of both scientific features of nature andmetaphysics of science.

7. PERIOD OF CONSOLIDATION (1961-2000)The previous section has given an account

of some excellent experimental and theoreticalscientists of first half of the twentieth century inIndia. It is somewhat satisfying when we thinkhow wide was their research field, and how hadthey achieved international fame in spite ofvarieties of limitations with no government grant,better not to speak about facilities for basicresearch, tools, techniques, source materials, andexperimentation. The research was only guidedby the urge of doing something great. India


became free from Colonial rule in 1947, and thegap between experimental and theoreticalknowledge was visible and became the demandsof the day. Efforts were made not only to buildnew institutions under TIFR, CSIR, DAE, IIS,BARC,RRI, etc, but also under old and newuniversities, the main aim being how to minimizethe gap between theoretical and experimentalunderstanding and to make India self-sufficient.In astronomy, astrophysics and physics, thegeneral thrust in physical science was to set upmajor observation facilities in cosmic ray, optical,infrared, millimeter and radio wave bands ofelectromagnetic spectra to get a realistic pictureof the universe and to know more about theircharacteristics.

The cosmic ray research was of courseoriginally started by D.M. Bose and his group inCalcutta, who detected cosmic ray particle tractsin photographic plates exposed in the Himalayanregion, and also successful in identifying newparticles with a mean mass 200 times that of theelectron, much before Powell’s systematicdevelopment of photographic emulsion method,and pi-mesons in cosmic rays. It was generallybelieved that the cosmic rays enter the atmospherefrom outside the earth, i.e. from extra-terrestrialsources. Cosmic ray in its penetrating power canbe perceived after their traversing the wholecolumn of earth’s atmosphere, equivalent to a layerof water ten meters thick, can reach any points onthe earth. TIFR cosmic group under the initiativeof Homi Bhabha, the then Director of the Institute,took lot of initiative and used balloon flights forstudy of cosmic ray. MGK Menon, who was thesecond man in-charge of TIFR and the right handman of Bhabha was a student of W. Pauli and alsoan expert on cosmic rays. He took great interestin the preparation of high-precision measurementtechniques and use of large strapped emulsionstacks in the flights to obtain important results likeproperties of strangeness (quantum attributes ofelementary particles), decay mode of heavyunstable particles—called K-mesons, associated

production in pairs, produced by cosmic rays.Menon also took initiative for cathode rayexperiments in Kolar Gold Fields in Mysore(KGF), found to be an ideal place having pits ofvarious depths extending up to 2 miles below thesurface. The experiments were carried out incollaboration with groups from England and Japanwhich collected most comprehensive depth-intensity data for muons up to the depth of 9,600ft below the ground. The first natural atmosphericneutrino interactions were also detected in KGF(1965). The nucleon-decay experiment to a lifespan of 1031 years was also carried out withdetector which was operational in 100 toncategory. BARC (Bhabha Atomic ResearchCentre) provided early leadership from the timeof Bhabha (since 1960) in using inelastic scattering(i.e. when the scattering particle looses energy bycausing excitation of the struck nucleus) to proveelementary excitations in condensed matter. RRI(Raman Research Institute, Bangaluru) some timein 70s took systematic studies specially on liquidcrystals and in library-scale studies in newarrangements of liquid crystals, and decodingstage with a stacking of disc-like molecules, thisbeing possibly the highest point in the life of RRIduring 1970-78.

The atmospheric studies which startedalso in Kolkata carried out important work on lowfrequency propagation in the ionosphere,aeronomy and the ozone layer in the upperatmosphere (15 to 30 km above the earth’s surfaceand responsible to absorb a large proportion ofSun’s ultraviolet radiation).The work in radioastronomy also started in Calcutta and renewedwith great interest and in a large scale in TIFR in1962 under the active interest of Bhabha andMenon. It was through the encouragement ofMenon, Govind Swarup and his group wassuccessful in setting a large telescope indigenouslyin Ootacamund (Ooty) on a hill with a slope ofthe same latitude of the place and barrel placingin parallel to the axis of the earth. It had a paraboliccylindrical antenna (530 m × 30 m) stretched


towards north-south with facilities of scanningeastern sky, and began active participation sinceits commissioning in 1970. Ooty Radio Telescope(ORT) is used for observing sensitive and highangular resolutions of extra galactic sources at afrequency of 327 MHz using the method of lunar-occultation (Ramakrishna,2010). It has alsoenabled extensive observations of pulsars,supernovae, apparent angular size of galaxies withtheir energy flux, The optical telescope facilitiesalso dates to this period and supply interesting dataon discovery of rings surrounding Uranus,measurement of star clusters and their kinematics.GMRT (Giant Metrewave Radio Telescope,Bangaluru) was also ser up by TIFR consisting of30 antenna each of 45 m diameter works over awide frequency of 150-1500 MHz, effort beingmade to widen the frequency range to 40 MHz –1500 MHz. Signals from all antennas are broughtto a control room to correlate using hardware andsoftware correlators to process 32 MHz ofbandwidth around the operating frequency. RRIand IIA (Indian Institute of Astrophysics,Bangaluru) and various other institutes work incollaboration in mapping of the sky andexchanging important data between them.

Various efforts were being made tocorrelate the theoretical and experimentalunderstanding and the search continued for moreand more subatomic particles and theircharacteristics, since they were generallyconceived as the building blocks in the formationof matter in the universe (Mehra and Reichenberg,1962; Mukherji, 1971-72; Mitra,1984; Hawking,1987; Gell-Mann, 1994; Pal,2008;). Major focuswas obviously given on the compositeness ofatomic nucleus. With the discovery of neutron-particle which is electrically neutral, and yet foundto be a basic constituent of atomic nucleus (whereatomic mass is concentrated), and was also on parwith the proton, it was found that both lie withinthe same ‘shell structure’. Under nuclearspectroscopic instrument, it was also noticed thatthe atomic spectra and molecular spectra have a

striking resemblance thereby suggesting that thenuclear constituents ( i.e. ‘nucleons’ consisting ofproton and the neutron) serve a similar role inshaping nuclear structure, as it is in the case ofmolecular structure (with their electronic degreesof freedom energetically suppressed so that theybehave effectively like elementary constituents).The ‘nucleon-like state’ was also observed byexperimental scientists in cosmic rays producedin high energy accelerators, and in resonancesproduced by the bombardment of pi-meson beamson proton targets in the laboratory. It was firstconjectured by that the nucleons must be heldtogether by short-range forces (because of themuch less dimension of the nucleons), or ‘meson’(heavy quanta, the rest mass of these quanta wasestimated to be about 200-300 times heavier thanthe electron estimated by using ‘UncertaintyPrinciple’ of Heisenberg ). This was known as ‘pi-meson’ (or ‘pion’), but it entered into lot ofcontroversy for not having the strong interactiveproperties as expected. Later on it was found that‘pi-meson’ has a partner, ‘kaon’ in cosmic rays,which could produce powerful meson resonancesat its excited states by energetic pion- beams, inparallel with the corresponding nucleon (orbaryon) in the laboratory. Following this processa large number of nucleon- and pion-like particles(collectively called ‘hadrons’, signifying large,massive particle like mesons and baryons) werefound which created serious doubt as to theproperty of elementarity of atom. It was of coursefound that some of the fundamental particles ofatom could be better understood if they were madeup of even smaller components, an idea that leadto the concept of quarks (as a fundamental particlethat combines to form other particles, includingproton and the neutron, the particles that make upthe atomic nucleus). Initially, quarks wereconceived having three fold properties of forces(or flavours, proposed by Gell-Mann )—Up(charge + 2/3, mass 0.378 ), Down (charge – 1/3,mass 0.336), and Strange (charge – 1/3, mass0.540), combing as doublet, triplet composites of


more elementary constituents. [The mass isexpressed in Gigaelectron volts (GeV) followingEinstein’s mass and energy formula]. These threeflavours together with their antiparticles provedadequate for the description of about 300 hadronsand their resonances (hadron sector).

Fourfold classification of forces —electromagnetic, strong-nuclear, weak-nuclear andgravitational, which govern particle interactionsof different kinds (called Lepton sector) were alsoattempted. Of these, the electromagnetic forceshave already been encountered in atomicinteractions, and strong-force in nuclear levelinteractions. The gravitational force is of courseis most tangible, but conceptually most bafflingof all. The weak-nuclear force is noted inphenomena like β-decay whose feature of missingenergy and angular momentum has beenintroduced in the concept of ‘neutrino’ (partner),a mass-less, charge-less particle, which can travelthousands of miles unnoticed to accompany theβ- particle (electron). Its existence as a partner ofelectron was also experimentally proved. Someparticles of course exhibit both weak andelectromagnetic force interactions and are giventhe generic name of ‘lepton particles’(means smallor light), which have maintained their elementarity(along with their partners which makes themweak). Three more quark flavours but muchheavier than the earlier three were also postulatedas properties of quarks. These are—Charm (charge+ 2/3, mass 1.500), Beauty (charge – 1/3, mass4.720) and Top (charge + 2/3, mass 174.000). Thetheory behind the colour force is called quantumchromodynamics (QCD). The muon-particlewhich has properties similar to electron but 200times heavier also participates in weak andelectromagnetic interactions, so is tau- particlewhich is 17 times heavier than muon-particle, theirpartners are being searched out. Attempts are alsomade to explain effects of interaction of theseforces through the use of group structures and theireffects in terms of various field reactions andproperties. Mendeleyev’s classification of

elements through group structures might haveprompted the idea of field for better understandingof the particle properties. First, theElectromagnetic theory of Maxwell was examinedand it was found that electromagnetic field hasnot only the underlying unity of both electricityand magnetism, but also supports the theoreticalproperties like, charges and their conservation,gauge fields as force media and charge carriers(invariance under gauge transformation leadingto conservation of charge, a kind of symmetry fortranslational and rotational invariance)besidesparticle interpretation at the hands of Planck, Boseand Einstein. The gauge concept gave a newmeaning to the entity called ‘charge’, not only asa measure of force between charged particles, andis strictly conserved as a result of its universalcoupling to a ‘gauge field’, of which the photononce again is a non-trivial example. The theory ofquantum electro-dynamics (QED) based onphoton field (having mass-less vector, boson) hasgot spectacular experimental success in predictingthe effect of electromagnetic interactions (1 in 1012

accuracy). It has also a theoretical property, knownas ‘Renormalizability’, which ensures freecalculation of physical effects to infinity (anyarbitrary order) through suitable redefinitions ofelectron mass and charge. In this sense it is auniversal carrier of electric charge but does notpossess any charge of its own. May be colourcarrying gluon (a type of boson responsible forthe strong force between quarks) field, photonfield, vector field or others which is a right kindof vehicle as carrier of charges, as required by thetheory to explain the forces. The way the periodictable was based on group structures, the similarapproach is possibly being attempted for a possiblesolution.

Boson-Fermion Classification ofparticles was another revolutionary concept. S.N.Bose (1924) had advocated a new form of countingof quantum states for truly indistinguishableparticles, a revolutionary concept which drewconstant endorsement not only from Einstein but


also from Schrodinger (1926), Heisenberg (1927)and Dirac (1928). According to the Principle ofIndistinguishability, the wave-function of a trulyidentical particles must be totally symmetric withreference to an interchange of the labels of anytwo of them. The photon was the first non-trivialexample of this principle. Thus the wave-functionfor an n-photon state, specified by their respectiveand states of polarization (or spin) should havethis symmetric property. For any other of identicalparticles whose intrinsic angular momentum orspin is an integral multiple of Planck’s constant(h), the corresponding wave-function must betotally symmetric. There is another class of(identical) particles of intrinsic angular momentumor spin is half-integral (of Planck’s constant h)which obey the anti-symmetric property withrespect to the interchange of any two particlelebels. The anti-symmetric property automaticallyensures that such particles must obey Pauli’sExclusion Principle (their wave-function wouldvanish when any two particles with identicalnumbers occupy the same position in space). Thecounting rule for the second type of particle wasgiven by Fermi (1926) with appropriatemodification to Bose’s rule. The electron (spin½ h) was the first non-trivial example of the secondtype. A few particles have been identified as :Boson particles (with integral spin)—photon,alpha-particle, pi-meson, W-boson and gluonwhich satisfy Bose-Einstein statistics; andFermions (half integral spin)—electron, nucleon,triton, neutrino and quarks which satisfy Fermi-Dirac statistics. Pauli has further suggested thatBoson-Fermion classification can be axiomaticallyderived from the very foundation of quantum fieldtheory under general conditions (Lorentzinvariance, causality and locality of basic fieldoperators). A new symmetry between Boson andFermion systems has now been proposed to erasethis distinction.

Another situation was seen whenNewtonian equations which admitted a relativistic

generalization for first moving objects, andHamiltonian equations of motion (or quantumtheory) for small objects/particles, the latter beingadaptable to Heisenberg form of quantummechanics (alternative to Schrodinger form). Thesmall particles, not fast enough, created lot ofproblems. In order to make a compromise betweenthe two opposite concepts (Dirac floated the idea)of particle and anti-particle on the basis ofmathematical formalism, and argued forrelativistic quantum mechanics of electron as anantiparticle of positron having opposite mass andspin, opposite sign for charge, magnetic momentand lepton number, result being simultaneousdestruction of both as particles and the entire massconverted into energy. Though the existence ofanti-particles for all types of fermion- particleswere generally believed, it was taken as a non-trivial solution in the absence of experimentalverification. The concept of charge with referenceto nucleon were thought to exist in two distinctcharge states much like two spin states of anelectron, viz., isospin and flavor, the former is thesimple manifestation of the latter. The isospinspace (or isotropy of charge space) in a preferreddirection and symmetry of near equality of massesare maintained for isospin multipliers. Stronginteractions at the hadronic and quark levelsindeed respect this symmetry. Weak interactionviolates isospin symmetry as seen from the ratherlarge mass differences within its multiples. Varioussymmetry of group representations like U (1), SU(2), SU (3), SU(6), were applied for explanationof these interacting forces. More sophisticated useof group symmetric theory was first made inunifying first the electromagnetic and weakinteractions, and then put under Grand Unifiedtheory (GUT) of electro-weak and stronginteractions. It has been found that each physicalprocess leading to infinite variations due to theparticipation of fermion is cancelled in the sameway an offending fermion is replaced by acompanion boson. Boson-Fermion symmetry(SUSy) is virtually a doubling of number of


elementary particles since each particle or fieldof conventional type now requires that a bosonparticle to have an identical SUSy partner. Thus,photon and photino (spin 1 & ½ respect.), gluonand gluino (coloured spin ( 1 & ½ respect.), leptonand slepton (spin ½ & 0),W boson and wino (spin1 & ½), Higgs boson and Higgsino (spin 0 & ½),Graviton and Gravitino (2 & ½) and so on arefermion - particles and their SUSy partners. Thuseach conventional boson must have a fermionSUSy partner having identical charges, forexample, boson and photino (photon’s SUSypartner) would have a spin –+ ½ (charge neutral)and vice versa. None of these hypotheticalparticles have yet been observed but thetheoreticians are hammering on incessantly.Presently, a theoretical framework, ‘theory ofsuper-symmetry’ has been worked out forprediction of a rich crop of new heavy particles.

However, classification of elementaryparticles is explained by a Standard Model basedon weak, and electromagnetic fundamentalreactions, using mediating gauge bosons, likegluons, W(-), W(+) and Z bosons, and the photons.Apart from 24 fundamental particles (12 particlesand their associated anti-particles) which are theconstituents of all matter, it also predicts theexistence of a type of boson, known as Higgsboson (after the name of Edinburg Universityphysicist, Peter Higgs, existence of which is nowexperimentally verified). This has been known forseveral years, and most particle- physicists ofcourse do believe that the model is an incompletedescription of nature. A few deviations havealready been noticed like, neutrino particle masshas already been detected through experiments,though it was originally thought to be mass-lessparticle; tachyon, another hypothetical particlewas floated by ECG Sudarshan that moves fasterthan light. It is a great challenge and strikes at thebase of particle physics and breaks Lorentzinvariance and the theory underlying specialrelativity. Feinberg proposed that tachyonicparticles could be quanta of a quantum field with

negative squared mass and soon realized thatexcitations of such imaginary mass field do not infact propagate faster than light theory, ratherrepresents an instability known as tachyoncondensation. No compelling evidence for theirexistence has been found. Apart from this fact,the work of Virendra Singh on Regge pole theoryfor coupling coulomb scattering (caused by theelectrostatic field surrounding nucleus), pion-nucleus scattering are note worthy. Hisinvestigation of SU(3) as an octet operator ofdecay interaction, the decay of baryon decupletinto baryon and mason octet was investigatedalong with a new provision of sum rule connectingvarious decays (known as Gupta- Singh rule). TheSU(6) symmetry for assessing correct spectrumof hadron states were also putforward leading toSU(6) mass formula (known as Beg-Singhformula). Singh’s investigations of boot-straptheory for understanding spectrums and theircoupling leading to the discovery of stronginteraction coupling constant as well as strongcoupling theory based on Skyrmion dynamics andits relation to Large N QCD are consideredimportant contributions by scholars in the field.Another interesting branch, called string fieldtheory on the basis of duality concept betweenstrong and weak interactions, where small one-dimensional string replace the point particles ofquantum theory, suggested by Ashok Sen of HarishChandra Institute in Allahabad, has brought amajor breakthrough in the field with wideimplications, according to one group of scientists.Interesting activities are being pursued in the areaslike, branes, tachyon condensation and the energylandscape of string field theories.

An active engagement in researches hasbeen found in this period between the particle-physics (microphysics) and astrophysics(macrophysics). This two-way traffic perhapsprovides the biggest challenge for physical scienceas a whole, which has been occasioned by majorstrides in both fields. Some likely consensus hasindeed evolved in the form of Standard Model for


weak and electromagnetic interactions, and QCDfor the strong interaction between quarks andgluons. The still bigger unifying principles ofGUT, SUSy etc may be regarded as attempts todeal with further unanswered questions like,mechanism of coupling electro-weak and stronginteractions at a very high energy state, theoreticalspeculation of existence of a very massive particle,e.g. X-boson awaiting experimental verificationand so on.

The astrophysicists have apparently givena solution to this problem by put-forwarding amodel, known as ‘Big Bang Model’. It explainsthat Big Bang during the early evolution of theuniverse acted as Nature’s powerful acceleratorand collisions were very frequent, the temperatureand density were very high. As a result, a varietyof particles, some very massive and difficult todetect since they interact too weakly produced inthis early phase and dropped out of the equilibriumconfiguration, because the reaction rate could notcope up rapid expansion and cooling of theuniverse, leaving behind only the relics of thoseparticles. The masses, lifetimes, and interactionsdetermine their relative survival rate as well asthe manner in which they presumably influencedthe subsequent evolution. It is not easy to get nearthe steady state moment of Big Bang (on alogarithmic time scale) which implies a hugeextrapolations in time of presently expandingHubble flow of distant objects in the universe, tothe epochs when the matter in the universe wasmuch denser and hotter than it is today. However,the observations by Edwin Hubble had shown thatthe universe was expanding (Theory ofexpanding universe), and as such the thought ofstatic universe (Steady State theory propoundedby James Jeans, Fred Hoyle, J. Narlikar and others)is untenable under general relativity. Refutationof steady state was further verified by the cosmicmicroscopic background radiation. According toStephen Hawking, the discovery of microwaveradiations put a final nail in the coffin of the steadystate theory. However, various interpolations are

being made for better understanding. These twoway traffic between micro- and macro-physics aremoving at a rapid pace. Indian physical scientistssurvive in this dilemma and between these twolines.

8. CONCLUDING REMARKS – A DILEMMA

In fine, it may be said that the concept ofuniverse and physical ideas related to it get ameaningful and concrete picture in its evolutionaryprocess through the centuries. The Sāmkhya andother Indian philosophical schools conceived atomas the basic unit of matter and of universe, andgave a hypothetical as well as speculativeexplanation of five elements, earth, water, fire, airand ākāśa (space, the atmospherical regionbetween the earth and the sun) based on atomshaving varieties of properties like, motion, touch,colours and flavours etc. Even duality principle,like purua and prakti, śiva and śakti, sulfur andmercury, was adopted in containing the energiesof two opposite forces to neutralize. Greeks had asimilar atomic concept, but not so clearer as thatof the Indians. Scientists from sixteenth centuryonwards have made persistent effort to penetratedeeper and deeper into Nature through telescopic,spectroscopic and satelite observations tounderstand and interpret it in all its aspects. Theconcepts of atomic, sub-atomic and cosmic world-view have come to a stage, by observation,experiment and application, to a point beyondwhich the scientists cannot proceed. Even themodern explanation of the properties of charge ofquark by colour and flavour, and the concept ofanti-particle reminds the metaphysical conceptsof the early Indians leading us to varieties ofparadox in our modern day explanation. Just asphysical sciences have given us control over thephysical world, so the life sciences also enable usto control the inner world to a great extent. Thisholds true both in case of physical world andbiological world, the boundaries of knowledge ofwhich appear to have been reached which isdifficult to cross. This is due not to any lack of


experimental technique or the inadequacy of thedialectic tool but to the nature of things inquiredinto. The scientists are now faced with questionswhich belong to realms of metaphysics andphilosophy. They are concerned with questions,such as coexistence of the external and the internalworld, possibility of natural laws being productsof the human mind, relationship between theobserver and the observed and that between mindand matter, and the criterion of certainty.Scientists’ knowledge is to create and satisfymaterial needs through discoveries and inventions,and should have to face questions of philosophywhich were once thought to be mental exercisesonly. The basic assumption of scientific enquiryis that there exists a real world of matter and energyin space-time independent of the observer. It doesnot perhaps represent the whole truth. Theobserver is perhaps an inseparable part of theworld he is observing. He has taken him out onlyfor the sake of convenience to systematize theknowledge of what is outside of his self. He hasin a way dichotomized Nature into an internalsubjective world and an external objective world.He is trying to have a closer view in such a wayas if a part is trying to understand the whole. Thephysical scientists of today is closer to thephilosophy that Man is one with Nature, that mindand matter are only different facets of a singlereality. The laws of the external world are creationsof the human mind, and the existence of the humanmind requires possibly an indispensablepartnership with Nature.

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