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Lecture: ASPECTS OF ALBERT EINSTEIN’S CONTRIBUTIONS TO PHYSICS

ASPECTS OF ALBERT EINSTEIN’S CONTRIBUTIONS TO PHYSICS

Authors: AnandBS

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“Life is a gift and if we agree to accept it, we must contribute in return. When we fail to contribute, we fail to adequately explain why we are here.” This is what Einstein believed about life during his life. BIOGRAPHY Albert Einstein was born on March 14th, 1879 in Ulm, Wirttemberg, Germany. He was the first child to a bourgeois Jewish couple. When his parents moved to Italy in 1893, Einstein dropped out of the school and applied to study Mathematics and Physics at the Swiss Polytechnic Institute in Zurich, in 1896.this was the place where he met his wife, Mileva Maric. Both graduated in 1900. Following his completion of Graduation in 1900, he went on to work as a teacher in a series of posts in Germany and Switzerland and finally settled in Bern, Switzerland, in 1902 as an examiner at the Swiss Patent Office. He received his Doctoral degree in 1906. INITIALIZATION The year 1905 has been termed Einstein’s “Annus Mirabilis” or miracle year, because it was in this year, he published three of his most important papers to “Annalen der Physik” (or Annals of Physics), a German Scientific Periodical. These papers mainly dealt with the topics as follow. · Special theory of Relativity. · The law of mass-energy equivalence, E=mc2. · Quantum Theory. · Brownian motion. In subsequent years, he theorized that the laws of Physics, including both Mechanics and Electrodynamics, are the same for all observers in all frames of reference. This theory, known as General Relativity, was fully formulated in 1915. However, while his Relativity theory won him the position of international prominence, it was his contributions to Quantum theory (I.e. Einstein’s papers on the Photoelectric effect), that won Einstein a Nobel Prize in 1921-22. Einstein also played a considerable role in bringing a change in the political balance of power in the 20th century through his scientific foundation in the development of Atomic Energy. BRIEF EXPLANATIONS I. THEORY OF RELATIVITY:- a. SPECIAL THEORY:- The first paper on the Special theory of Relativity (1905) presents the theory already in the final form. In a second paper published a short time later, Einstein drew the most important conclusion from the theory, namely, the equivalence of Mass and Energy, expressed in the celebrity equation, E=mc2. b. GENERAL THEORY:- The history of the General theory of Relativity is quite longer. In a survey of Special theory of Relativity in 1907, Einstein pointed out the necessity of a generalization and presented the fundamental idea that the generalization must be based on the equivalence of inertial and gravitational mass. A paper written in 1911discusses some of the conclusions from the General theory concerning the influence of gravitation on light: · The influence of a gravitational field on the frequency of spectral lines (gravitational red shift) · The bending of light rays by the gravitational field of the sun. After much further work-mainly on the mathematical foundations of the theory, the definitive form of General Relativity was published in 1916. By this time, Einstein had already derived the third “astronomical effect” of General Relativity, namely, the Motion of the Mercury Perihelion. c. Further work on GENERA: THOERY:- The problems of General Relativity have occupied Einstein to this day. The three main problems which appear to have particular importance are-Cosmology, the problem of motion, the unified field theory. · Cosmology: - All of modern cosmology goes back to Einstein’s paper of 1917, in which he first applied General Relativity to the questions of Cosmology and thereby put cosmological speculation on a firm basis. Einstein’s initial consideration was that the universe is static, but the later development (by fantastic astronomers like Stefen Hawking) has mostly favored the “the expanding universe”, in view of strong astronomical evidence. · General Relativity was originally based on two independent hypotheses: the field equations for the gravitational field, and the law of motion for the material particles. Starting in 1927, the hectic work of deducing the law of motion from the field equations, Einstein reached at the definitive solution in 1949 (in collaboration with L. Infeld). Thus it was shown that the field equations alone suffice as a basis for the theory. · From the beginning, the theory of General Relativity was mainly a theory of the gravitational field. Other fields could be predicted through this General Relativity in an unambiguous way, once their structure was known which was not possible by this theory. Therefore scientists like Weyl, Kaluza, Eddington etc., tried to generalize the theory so as to achieve a unified theory of all fields. But they could not succeed. Finally Einstein himself steadily worked on it since 1923, repeatedly modifying the form of the theory. The latest version was initiated in 1945 and received its definitive form in 1945, published as Appendix II to the 4th edition of The Meaning of Relativity. II. QUANTUM THEORY:- After the inauguration of Quantum theory by Max Plank in 1900, Einstein became the foremost pioneer in the new field. His first contribution appeared in the same year (1905), in the same volume of the Annalen der Physik, as his first paper on Relativity. This theory introduced the concept of Photons or light quanta which provided a much wider path towards further work on quantum theory, like Bohr’s theory of atom. In Einstein’s later papers, 1917, he gave a new derivation of Plank’s law of radiation on the basis of transition probabilities, and the penetrating analysis of the properties of photons. Among Einstein’s contributions, we have his application of quantum theory to the theory of Specific Heats (1907), and more importantly, his papers on the quantum theory of gases (1924-1925). Some of these topics that he dealt in these papers are now called as Bose-Einstein statistics and the other are the ideas on electron waves which guided Schrodinger in his work on Wave Mechanics. III. THE PHOTOELECTRIC EFFECT:- Using his theory of quanta, Einstein explained the photoelectric effect. He showed that when quanta of light energy strikes atoms in the metal, the quanta force the atoms to release electrons. Einstein’s work helped justify the quantum theory. The photoelectric cell resulted from Einstein’s work. This device made possible sound motion pictures, television and many other inventions. Einstein received the 1921 Nobel Prize in physics for his paper on quanta. The work of Planck and Einstein quickly established the Quantum Theory, not only in light but also in many forms of energy. The quantum physics was born. IV. KINETIC THEORY OF MATTER:- In the years 1902-04, Einstein wrote a series of papers in which he established the theory of statistical mechanics or the Kinetic theory of matter, which derive the thermal properties of matter from the assumption that the matter consists of atomswhich move according to the laws of mechanics. The most renowned sequel was the third paper Einstein wrote on Brownian motion in 1905 itself. In these papers, on the basis of Kinetic theory, Einstein predicted the proposal of minute particles suspended in a liquid. (Such a motion had been observed about one hundred years earlier by the English Botanist, Robert Brown). Conversely, the experimental investigations of such motions led to a verification of the basic hypotheses of the Kinetic theory of matter. FINISHING The General theory of Relativity is one of the greatest intellectual achievements of all time. Its originality and unambiguous way of approach is more than that in Special Relativity. And far more so than Special Relativity, it was almost completely the work of a single man, Albert Einstein. The philosophic impact of Relativity theory on the thinking of man has been profound and the vistas of science opened by it are literally endless. To quote Max Born: “The idea first expressed by Ernst Mach, that the inertial forces are due to the total system of fixed stars, suggests the application of the theory of General Relativity to the whole universe. This step was actually made by Einstein in 1917, and from that time on, its called the beginning of modern development of Cosmology and Cosmogony, the sciences of structure and genesis of the cosmos. This development is still in full swing and rich in important results, though far from final conclusions.” CONCLUSION Albert Einstein’s greatest contributions to Physics were his syntheses of Mechanics and Electrodynamics through his Relativity theory, and his challenge to Newtonian Physics through his Quantum theory. However, the impact of his ideas was not limited to science: Einstein’s achievements influenced philosophy, art, literature, and countless other disciplines. As an individual passionate in his convictions and outspoken in his politics, Einstein transformed the image of the scientist in the 20th century. It comes as no surprise; therefore, that TIME magazine selected Albert Einstein as “Person of the Century” hailing him as “genius, political refugee, humanitarian, locksmith of the mysteries of the atom and the universe.” ASPECTS OF ALBERT EINSTEIN’S CONTRIBUTIONS TO PHYSICS “Einstein has made a universe and I can’t tell you how long it will last!” – G. B. SHAW.
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Physics Classification: 80-XX (INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND)