You have generously referred to me in your invitation to this function as an "Octogenarian researcher". One would become introspective on his or her eightieth year. Warm felicitations from friends, relatives and recognition from SAE International gives me overwhelming feelings. My mentors, distinguished emeritus Professors, Phillip S. Myers and O.A. Uyehara of the University of Wisconsin had visited this great institution long ago had already recognized the potential of this automobile faculty at MIT and hoped that the graduates of the auto faculty would be a great asset to the industries both in India and abroad. Very true indeed, judging from the significant contributions made by the alumni of MIT to the growth of automobile industry today! One unforgettable message from Professor Phil Myers on my recent graduation to the club of 80 + year old peers is very relevant to quote for the benefit of my counterparts. " You have to recognize that young people are smarter than you! Console yourself with the thought that, if the young people were not smarter than we, no progress would have been made. … Be glad that you have helped to bring about this progress. For limited, appropriate cases share your wisdom with younger persons."

With these exhilarating feelings I wish to share with you some thoughts on the relationship between fundamental forces of Nature and the processes of energy conversion. The theme is also propitious as this borders on the area of Spirituality and Science – a topic most dear to Bharat Ratna, Dr. A.PJ. Abdul Kalam, the distinguished alumni of this great Institution, who will shortly adorn the highest office of President of India.

FUNDAMENTAL BUILDING BLOCKS OF NATURE

Long ago, Greeks (Aristotle) believed that all the matter in the universe was made up of four basic elements-earth, water, air, and fire. Upanishads in India, in ancient times, identified these elements respectively as "Prithvi, Aappas, Vayu, and Thejas " and added one more element "Akash" to identify space in which these elements interacted with appropriate forces to sustain the universe. These were termed " Pancha Bhuthas," and the philosophers, by sheer inspiration, tried to unify all these into a coherent picture of space, time and matter. Although these cosmological descriptions transcend scientific reasoning and experimental validation, they serve to stimulate the highest scientific thinkers to embark on new theories supported by experimental verification.

Across the globe for the past fifty years, theoretical physicists are engaged in getting a unified picture of the nature by mathematical modeling and experimental verification. They are grappling to synthesize what they call the four fundamental forces, each of which is so different from the others. They are gravitational, electromagnetic, the strong and the weak nuclear forces. Gravitational force, which makes objects fall to the ground, is only attractive. Although this is the weakest force, it is the dominant force in the universe. The effect of gravity is felt over very large distances covering many trillions of kilometers through space to distant stars. This is the force that keeps the earth in its orbit around the sun along with other planets in their allowed orbits, prevents the stars from exploding and guides the galaxies in their determined courses through the universe.

But this gravitational force can be countered easily by electromagnetic force, which is called the second fundamental force in nature. Just by scrubbing a comb through our hairs, it is possible to lift small scraps of paper against gravity. This force is both attractive and repulsive, but have their effects felt only over limited distances although their intensity their intensity is many million times that of gravity. This is the force that makes the negative charges called electrons around positively charged nucleus, containing protons (positively charged particles) and neutrons (electrically neutral) in their determined orbits. The chemical nature of all elements in the universe is governed by the structure of the atom in relation to the electromagnetic force determining the orbital motion of these small negatively charged entities. On a microscopic scale, the atomic structure resembles the solar system, which however is on a macroscopic scale. When an atom is disturbed by another small entity, the orbital electrons are restructured and they take different orbital positions with release or absorption of energy. This is the essence of chemical reaction, endothermic or exothermic.

Strong and weak forces are nuclear forces of the atom and are identified as the third and the fourth of the fundamental forces in nature. Strong forces bind the particles (protons and the neutrons) together in the nucleus, overcoming the strong repulsive forces. When the nuclei are torn down by disturbances or when nuclei fuse together, tremendous amount energy is unleashed, more than one hundred times that released by chemical reaction. On a large scale, such reactions are occurring in the sun and stars that are shining. They are all nuclear furnaces with nuclear reactions occurring under the influence of the strong forces of nature. The weak nuclear force is responsible for radioactivity, which act certain heavy nuclei of matter particles. During radioactive decay of this matter, energy is released. The intense heat that is produced in the core of the earth is due to the weak forces. This can cause volcanic eruptions.

Within the last twenty-five years, scientists have tried to unify all these fundamental forces of nature into a single force, which manifests itself in different forms of the four fundamental forces. Abdus Salam (born in undivided India) along with American scientist Steven Weinberg and Sheldon Glashow received 1979 Nobel Prize for physics for showing how to unite weak and electro magnetic forces into one force. There are also theories to unite the strong nuclear force with it. But the only force elusive of this unification is the gravitational force. Recently, by intense scientific and experimental efforts, physicists are trying to unify all the forces by a new theory called Super Strings. Experimental verification of this theory requires very expensive and high-energy particle accelerator to probe into the atomic microcosm and building this is the real challenge facing the scientists.

Energy Conversion Processes in Practice and the Fundamental Forces of Nature

Presently, nearly 95% of the energy needs of our society are met by burning fossil fuels, which are non-renewable. The energy is stored in the chemical bonds of the fuel by the fundamental electromagnetic force of the orbiting electrons. When the fuel molecules in proper admixture with oxygen in the air are activated by external means, say a spark or intense heat, combustion (chemical reaction) takes place with the electrons in the fuel and oxidizer molecule getting into lower energy orbits of combustion products. The released energy is heat or thermal energy. This may be used as such for process or comfort heat. If mechanical power is needed (say for propelling an automobile,) this heat energy is converted to mechanical energy by a heat engine which irrevocably discards heat to the atmosphere as dictated by the powerful second law of thermodynamics. More generally, electric power is needed by society for multipurpose. So another conversion process namely, mechanical to electrical through a dynamo is needed. All these intermediate steps are colossal wasteful processes resulting in loss of efficiency and causing air pollution and global warming with the excessive discharge of exhaust products to the atmosphere. Humans in their voracious appetite for energy are depleting the precious and non-renewable fossil energy resources by adopting the indirect methods of energy conversion.

In contrast, if the fossil fuels are reformed to gaseous hydrogen, we can directly convert the energy in the hydrogen bond to electrical energy as in a fuel cell. Here we by-pass the thermodynamic cycle and employ a direct electro-chemical method of energy conversion like that encountered in a storage battery, excepting that here fuel-hydrogen is carried instead of stored electrical energy as in a battery. Direct processes are more efficient with very low losses and hence pollution. Space scientists were the first to use the fuel cell technology because of low weight of the energy converter without moving parts. Now steps are underway for terrestrial use of fuel cell as in an electric automobile.

Hydroelectric power generation is an exact example of making use of the second primary force namely gravity for direct energy conversion. The main virtue of hydropower is that it is the major source of energy "income" and is inexpensive. We are not spending the energy "capital" as we do when we burn non-renewable fossil fuels. Atmospheric pollution is totally absent in the conversion process. Like all direct energy converters, very high efficiencies (theoretically100% in the absence of frictional forces in the converters) are possible. Waterpower contributes about 1 % of the world and 4% of the energy input of the USA. Total potential of waterpower in India is not fully tapped, particularly in the regions of Meghalaya. While it is confined to those geographical areas where it is available, it also assists in flood control and in helping the rivers navigable. Siting of these plants have to be made with care, as the location on the earthquake prone fault line may be risky.

Space scientists are credited with development of lightweight and long-lived direct energy converters, which use nuclear energy even in the dark periods of their mission when solar panels are inactive. Natural decay of radioisotope is an example weak nuclear forces acting on the material to furnish heat, which is the input to one junction of a suitable thermoelectric generator. The other junction will give directly the electric power needed. Though in small quantities, this is a reliable source of uninterrupted power to operate the instruments on the spacecraft for a long time lasting the half-life of the isotope, which is of the order of 86 years. Terrestrial applications are also possible to power remote weather sensing stations located near the poles, where the isotope can be safely buried out of reach of humans and animals.

Photovoltaic transformation of solar energy directly to electricity is an example of the strong nuclear-fusion forces acting in the sun giving solar radiation sustaining life and every activity on the earth. Again it is the space scientists, who relied heavily on direct energy conversion by using solar panels. Solar cells have found terrestrial application for small-decentralized power stations in rural situations where electric power is not easily available. The inhabitants in such decentralized locations use radios, television and telecommunication equipments. These generators also bypass Carnot cycle limitation on efficiency and hence they are highly efficient and do not pollute the atmospheric air. In a large scale for electricity generations, reactors powered by nuclear strong forces operate by the thermal energy released by fission are now used in many parts of the world. The energy released is in the form of heat and this is converted to electric energy by conventional power plants, which are subject to efficiency limitation decreed by heat engine cycles. If in the future, fusion reactions by using deuteron molecules in the seawater are possible, there will be inexhaustible potential of power on the earth. Vast amount of power will be unleashed for producing electricity. Splitting water, producing hydrogen, can contain the surplus power. Hydrogen seems to be the source of clean power for the future generations.

There are many other examples of energy conversion from the wind, geo thermal wells, tidal and ocean thermal energy, which can be traced to one of the four fundamental forces of nature. Onsager, a noted specialist in thermodynamics, has proposed a unified theory of all the energy conversion devices by the application of irreversible thermodynamics using appropriate forces and fluxes, which contribute to power and efficiency. One conclusion from all these analysis is that direct energy conversion is a very beneficial transformation technology.

( Based on the course of Direct Energy Conversion taught by Professor O.A.Uyehara)