Prof. C. V. RAMAN AS A SCIENTIST – WRITER

 

A. RANGANATHAN

 

Some of the great scientists who are remembered, were skilled practitioners in the art of communication. In fact Sir Isaac Newton’s classic paper on Light and Colour which was published in the Phi­losophical Transactions of The Royal Society in 1672 James Clerk Maxwell’s celebrated paper of 1865 entitled A Dynamical Theory of the Electromagnetic Field published in the Philosophical Trans­actions of The Royal Society, Madam Curie’s account of the dis­covery of radium, Albert Einstein’s formulation of the Special Theory of Relativity in his paper On The Electro-Dynamics of Moving Bodies and Prof. C.V. Raman’s paper On The Molecular Scattering of Light in Water and the Colour of the Sea are memorable pieces of prose. Furthermore Prof. Raman’s monographs such as The Molecular Diffraction of Light, Lectures on Physical Optics and The Physiology of Vision are models of expository prose.

 

Like Sir Arthur Eddington, Sir James Jeans, Sir Lawrence Bragg, Sir Julian Huxley, Peter Medawar and Steven Weinberg, Raman made science fascinating to the layman. And listening to him, one could perceive the rhythm of modern physics. Furthermore his innumerable expositions of popular science – scientific essays like The Acoustical Knowledge of the Ancient Hindus, a selection of radio talks entitled The New Physics, as well as the texts of various addresses such as Monsoon Forecasting, Causality and Chance in Modern Physics and Music and Musical Instruments are at once sensitive prose and elegant pieces of scientific exposition.

 

Raman’s scientific writings reflect four distinguishing chara­cteristics: first, a sensitivity to colour; second, a creative use of the metaphor in the Newtonian tradition; third, a talent which can break through the meshes of a technical jargon and express itself in clear running prose that is at once simple and accurate; fourth, an ability to communicate effectively.

 

Raman’s sensivity to colour was an aesthetic experience. Indeed when one reads his descriptions of gemstones and flowers – remini­scent of Ruskin’s aesthetic responses to the Turner landscapes – one  realizes that the scientist was committed to developing a system of communication between visual aesthetics and the sciences. Here is a sensitive evocation of the Opal in his Lectures on Physical Optics: “Precious opal exhibits a striking play of colour. The finest specimens give brilliant monochromatic reflections over large areas, the colours ranging over the whole spectrum and altering with the angle of incidence of the light. Some specimens exhibit numerous small glit­tering spangles of colour, and others again an almost continuous sheen of iridescence. Some very beautiful and valuable opals are grey, blue or black in colour, the iridescence showing up by reflection against the dark background thus provided. Opals of a lighter tint are fairly transparent and in transmitted light exhibit hues approxi­mately complementary in the colour of reflected light. Opals usually show a bluish-White opalescence overlying the reflected colours, and if such opalescence is strong, the colour seen by transmitted light tends to a honey-yellow, the complementary tints then being less conspicuous.” And Raman’s description of the Jacaranda Mimosi­folia in his work on The Physiology of Vision is equally sensitive: “Another magnificent tree is Jacaranda Mimosifolia, the beauty of the foliage of which is far excelled by the splendour of the flowers which the tree bears in profusion and which makes it appear from a distance as if it were enveloped in a blue mist…….”

 

Prof. Raman’s famous “Letter to the Editor” on The Colour of the Sea which was published in Nature (November 1921) carries us along the very frontier of Molecular Physics on a wave of curiosity. In fact Raman’s sensibility is reflected in this Letter which makes the prose – based on a brilliant scientific: argument – an aesthetic pleasure. “The view” wrote Raman “has been expressed that ‘the much-admired’ dark blue of the deep sea has nothing to do with the colour of the water, but is simply the blue of the sky seen by reflection’. Whether this is really true is shown to be questionable by a simple mode of observation used by the present writer, in which surface-reflection is eliminated, and the other factors remain the same. Observations made in this way in the deeper Waters of the Mediterranean and Red Seas showed that the colour, so far from being impoverished by suppression of sky-reflection was wonderfully improved thereby. A similar effect was noticed, though some what less conspicuously, in the Arabian Sea. It was abundantly clear from the observations that the blue colour of the deep sea is a distinct phenomenon in itself, and not merely an effect due to reflected sky-light. When the surface-reflections are suppressed the hue of the water is of such fulness and saturation that the bluest sky in comparison with it seems a dull grey.”

 

This Letter led on to two historic achievements which are relevant to Optics as well as to aesthetics – the historic Royal Society paper On The Molecular Scattering of Light in Water and the Colour of the Sea (1922) and the equally historic discovery of the “Raman Effect” based on the physics of a change of wavelength in Light Scattering on February 29, 1928. Furthermore, the first visual impact of the Mediterranean Sea on Prof. Raman through a polarising Nicol Prism is comparable to that recallable aesthetic sensibility that one can still experience while reading Galileo Galilei’s Starry Messenger which first recorded the Galilean sight of the night sky through a telescope.

 

The creative use of the metaphor is a part of the scientific process. For instance, Sir Isaac Newton used a metaphor in for­mulating a theory of light. Again names Clerk Maxwell made use of the mechanical metaphors in trying to work out the mathematical methods in the fields of magnetism and electricity. And characteri­stically enough, Professor C.V. Raman viewed an entire area of scientific research as a metaphor in order to work out the physics of an inter-related area of scientific research. In fact, while studying the famous Whispering Gallery Phenomenon of St. Paul’s Cathedral at London in 1921, Raman was led on to the verification and con­tinuation of his earlier optical analogue experiments through the process of simulating this phenomenon optionally. This enabled Raman to demonstrate that the luminiscence of a pearl was similar in the sense that light got reflected around the surface of the pearl just as sound (according to the Rayleigh explanation) is reflected around the corners of a whispering gallery and thus carried. Indeed the Raman use of the metaphor in experimental physics is brought out in Prof. Ramaseshan’s observation that Prof. Raman “extended his acoustical studies on whispering galleries to show that the striking beauty of the pearl – the gem that does not require the services of a lapidary – is essentially because it is a leaky, spherical optical whispering gallery.”

 

To Professor Raman, no scientific problem was insignificant. Actually the physics of the countryside which inspired his youthful imagination, was an adventure of the mind. Here is a piece where Prof. Raman introduces to the fascinating world of Science and Rural Development: “The cycle of seasons so beautifully described in Kalidasa’s Rithusamhara is also the cycle of the life of the country­side in India. If one overslept like Rip Van Winkle in Washington Irving’s story and woke up unconscious of the lapse of time, a glance at the agricultural scene in any familiar area: would enable the date to be fixed within a week or two. Vast tracts in our country still depend exclusively on rainfall for the possibility of any kind of agriculture. The opening and shutting of the sluice-gates in the sky are therefore the most important events in the calendar of the man who tills the earth in these areas.....A former Finance Member of the Government of India is reported to have said that the budgets he had to prepare and present every year were “a gamble in rain”. This expression puts in a neat and forcible way the exist­ing preponderance of agriculture in the economy of India, and the controlling influence of the same. This relation between the weather and public finance appears to have been the principal reason for the establishment by Government of a Department of Meteorology during the last century.......It is necessary, in fact, in order to understand what is happening near the earth’s surface, to know what is happening far above it, and to correlate the two sets of facts. It is for this reason that it is now a regular practice in meteorology to investigate the upper air by observation of the movements of free baloons and also by sending up baloons con­taining instruments which automatically record the condition of the atmosphere at the higher levels or sent radio signals to an observer below.”

 

Raman conveyed a similar excitement while making a reference to his “Sight-seeing” at Mount Wilson Observatory in a radio talk on “The Stellar Universe”: “I remember ...... vividly the two nights I spent at the Mount Wilson Observatory in California….I came away tremendously impressed with the marvellous light-­gathering power of the great sixty-inch and hundred-inch reflectors. The great nebula in Orion, for instance, which in ordinary instruments appears as a shapeless area of great luminosity, appeared in the sixty-inch as a luminous patch of variegated colour determined by the light-emission of the gases of which it is composed.”

 

In a lecture delivered in 1933, Albert Einstein asserted that experiments cannot play an important role in, the development of a theory. For Einstein maintained that the creative principle resides in mathematics. In a certain sense, therefore, I hold it true that pure thought can grasp reality, as the ancients dreamed.” Interestingly enough, Professor Raman discussed this point in one of his radio talks. “To possess real significance”, observed Prof. Raman, “a scientific discovery must have both an experimental basis and a theoretical basis. Which of these aspects is the most important depends on the particular circumstances of the case, and a rough distinction thereby becomes possible between experimental and theo­retical discoveries Roentgen’s discovery of X-rays, for example, was clearly an experimental one, while Planck’s equally important dis­covery of the quantum of action was clearly in the field of theory. The manner in which a scientific discovery is made and the attitude of the investigator which makes such a discovery possible are obvi­ously different in the two cases.”

 

The interconnections between mathematical theory and ex­periment must be viewed not only in the context of what Einstein  had to say on this subject, but also in the perspective of Raman’s own scientific achievement. Indeed, while voyaging through the sea, Raman realized that the Einstein-Smoluchowski concept of ther­modynamic fluctuation could be extended to understand the mole­cular diffraction in liquids. Furthermore, the Laser Beam is not only an indispensable tool of the technologist, but has proved effective in the experimental verification of physical theories. For instance, Professor Raman had made theoretical predictions con­cerning the behaviour of Ultrasonic waves during the mid-thirties (1935-36), which were experimentally verified by a group of scientists (using Laser techniques) at the Columbia Radiation Laboratory in February 1963. And this mathematically elegant theory made Pro­fessor Max Born excitedly affirm that “Raman’s quick mind leaps over mathematics.”

 

In fine, Professor Raman a – great scientist as well as a sensitive scientist-writer – expressed his philosophy of life in a radio talk on “The Scientific Outlook”: “The man of science is just a student of nature and equally derives his inspiration from her. He builds or paints pictures of her in his mind, through the intangible medium of his thoughts. He seeks to resolve her infinite complexities into a few simple principles or elements of action which he calls the laws of nature …..The pictures of nature which science paints for us have to obey these rules, in other words, have to be self­-consistent. Intellectual beauty is indeed the highest kind of beauty. Science, in other words is a fusion of man’s aesthetic and intelle­ctual functions devoted to the representation of nature. It is therefore the highest form of creative art.”

 

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