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Evolution of Physics Dr Hameed A Khan Physics is the most basic of all sciences and its importance in our everyday life cannot be emphasized enough. In order, to capture the true picture of physics' contribution to improving mankind's quality of life, one must take a journey back in time and follow the road to the evolution of science and technology in general and physics in particular. Early traces of the evolution of science can be dated back to the 7th century BC-Greek era; however, those of technology are difficult to identify. It is often said that technology came before science, because mankind in its primitive ways pursued methods of repetitive hit and trial until a way was found to satisfy the requisite need. The mother of all inventions, need, led man to do technology long before he could or would do science. It is for this reason that some historians and technologists go to the extent of stating that the wheel, which is considered to be the invention that fueled the S&T evolution, was invented by technology and not science. After the Greeks, history experienced the era of the Romans, who were more focused on technology than science and, therefore, this period experienced a little progress in the realms of science itself. During the period of 'After Jesus', the Chinese made noteworthy contributions to science and technology (papermaking, gunpowder), and then came the era of the Muslims. The Muslims helped spreading the influence of science from the Mediterranean eastward into Asia, where it picked up contributions from the Chinese and the Hindus, and westward as far as Spain, where Islamic culture flourished in Córdoba, Toledo, and other cities. Though little specific advances was made in the realms of physics, the Muslims ensured preservation of Greek science and kept it alive during this period. The much preserved and patronized science kept by the Muslim world made possible the revival of learning in the West, beginning in the 12th and 13th century. During this period, the Muslims experienced their downfall, not only in terms of their dominance in the world, but also in terms of their dominance in science. The Mongols destroyed Baghdad, which was one of the centres of Muslim scientific literature and civilization. Though the Turks continued to patronize science, much of the libraries and books preserved by the Muslim world no longer existed. In the year 1453, Istanbul also fell to the Turks. During this period, the intellectual community of the Muslims (especially those who spoke Latin) fled to Western Europe, more specifically Italy and then on to Greece. With their comfort in communication, they helped spread scientific knowledge in European languages across the western part of the continent. Some of the books of Muslim scholars and scientists were even translated into Latin and other European languages. During the dark and middle ages of Europe, the Church was in control of the State, and religion guided the society to abide and follow what was divine decree without questioning. As the norms of these ages promoted nothing but blind following, the culture of science in Europe could not develop, as science dwells purely on query. During the period of renaissance, the control of the church weakened and people started questioning religious and societal beliefs. In this environment, scientific queries were also re-generated, which marked the beginning of an era of progress and development in science and its realms. The physics of Newton during his era is considered to be remarkable in the true sense of the word. It is from here that the foundations of modern science and modern physics were grounded. The full explanation of celestial and terrestrial motions was not given until 1687, when Newton published his Principia [Mathematical Principles of Natural Philosophy]. This work, the most important document of the Scientific Revolution of the 16th and 17th centuries, contained Newton's famous three laws of motion and showed how the principle of universal gravitation could be used to explain the behavior not only of falling bodies on the earth but also planets and other heavenly bodies. To arrive at his results, Newton invented one form of an entirely new branch of mathematics, the calculus (also invented independently by G. W. Leibniz), which was to become an essential tool in much of the later development in most branches of physics. The journey of science that originated in mystery, passed through astrology and astronomy, moved on from geocentric to heliocentric descriptions of the solar system, gone from circular to elliptic orbits of the planets, progressed from kinematics to dynamics and finally reached the grand synthesis of Newton and classical mechanics. In the 17th century, focused and specific interrelationships between science and technology. Watt invented the steam engine in 1765. By the end of the 19th century, the interaction and inter-linkage of scientific discovery and industrial revolution had materialized. The period of early 18th century up till early 20th century is appropriately denoted as the time when the foundations of modern science were laid. During these 200 years or so, science moved from Newton on to Einstein, from macrocosmos on to microcosmos and from classical physics to quantum physics. The key characteristics of this era include critical observations, ingenious experiments, unique insight and patient incremental understanding, which ultimately led to amazing and unorthodox synthesis and suggestions. This was an era of gradual evolution, intermittent revolution through discoveries, independent development of fundamental modern scientific fields, as well as intertwined and interlinked progression of cross-disciplinary realms. During this time-frame, science was led by innovation breeding innovation, which materialized the establishment of the broadest laws of science. It was quite clear by the beginning of the 20th century that the most fundamental entities of nature are not atoms. It is indeed a great achievement of mankind to have uncovered the secrets of the inner structure of the atom. Near to the end of the 19th century, scientists realized that classical mechanics had its limitations and was unable to explain a number of upcoming phenomena. Quantum physics and light quanta evolved due to the resolution of the new phenomena regarding emission and absorption of electromagnetic radiation by matter. In 1905, Einstein used the quantum theory to explain the photoelectric effect, and in 1913 Niels Bohr again used it to explain the stability of Rutherford's nuclear atom. In the 1920s, the theory was extensively developed by Louis de Broglie, Werner Heisenberg, Wolfgang Pauli, Erwin Schrödinger, P. A. M. Dirac, and others; the new quantum mechanics soon became an indispensable tool in the investigation and explanation of phenomena at the atomic level. Special relativity has unified the concepts of mankind regarding mass and energy, by showing the equivalence of both. The discovery of nuclear fission by Otto Hahn and Fritz Strassmann (1938) and its explanation by Lise Meitner and Otto Frisch provided a means for the large-scale conversion of mass into energy, in accordance with the theory of relativity, and triggered as well the massive governmental involvement in physics that is one of the fundamental facts of contemporary science. The growth of physics, since the 1930s, has been so great that it is impossible in a survey article to name even its most important individual contributors. Among the areas, where fundamental discoveries have been made more recently are solid-state physics, plasma physics, and cryogenics, or low-temperature physics. Out of solid-state physics, for example, have come many of the developments in electronics (e.g., the transistor and microcircuitry) that have revolutionized much of modern technology. Another development is the maser and laser (in principle the same device), with applications ranging from communications and controlled nuclear fusion experiments, to atomic clocks and other measurement standards. [The writer is a Scientist Emeritus, PAEC, Islamabad]
