:-Physical World:-
Humans have always been curious about the world around them.
The night sky with its bright celestial objects has fascinated humans science time immemorial .The regular repetitions of the day and night the annual cycle of seasons the eclipses the tides the volcanoes the rainbow have always been a source of wonder.The world has an astonishing variety of materials and a bewildering diversity of life and behaviour the inquiring and imaginative human mind has responded to the wonder and awe of nature in different ways .One kind of response from the earliest times has been to observe the physical environmental carefully ,look for any meaningful patterns and relations in nature phenomena and build and use tools to interact with nature .This human endeavour in course of time to modern science and technology.
The world Science originates from the Latin verb Scientia meaning "to know".The Sanskrit word Vijnan and the Arabic word ILM convey similar meaning , namely 'knowledge ' science in board sense is as old as human species .The early civilization of Egypt.India .Greece. made vital contribution to its progress from sixteen century onwards , great strides were made in science in Europe . By the middle of the twentieth century science had become a truly international enterprise, with many culture and countries contributing to its rapid growth .What is science and what is the so-called Scientific Method ? Science is a systematic attempt to understand natural phenomena in as much detail and depth as possible and use the knowledge so gained to predict , modify and control phenomena . Science is exploring ,experimenting and predicting from what we see around us .The curiosity to learn about the world, unravelling the secrets of nature is the first step towards the discovery of science.
The scientific method involves several interconnected steps: systematic observations,controlled experiments ,qualitative and quantitative reasoning mathematical modelling prediction and verification or falsification of theories .Speculation and conjecture also have a place in science; but ultimately , a scientific theory to be acceptable must be verified by relevant observations or experiments . There is much philosophical debate about the nature and method of science that we need not discuss here.
The interplay of theory and observation for experiments is basic to the progress of science is ever dynamic .There is no 'final theory in science and no unquestioned authority among scientists. As observations improve in detail and precision or experiments yield new results ,theories must account for them,if necessary ,by introducing modifications.Sometimes the modifications may not be drastic and may lie within the framework existing of theory . For example , when Johannes Kepler (1571-1630) examined the extensive data of planetary motion collected by Tycho Brahe (1546-1601), the planetary circular orbits in heliocentric theory ( sun at the centre of the solar system) imagined by Nicolas Copernicus (1473-1543) had to be replaced by elliptical orbits to fit the data better . Occasionally,however,the existing theory is simply unable to explain new observations.This causes a major upheaval in science . In the beginning of the twentieth century, it was realised that Newtonian mechanics ,till then a very successful theory ,could not explain some of the most basic features of atomic phenomena similarly then accepted wave picture of light failed to explain the photoelectric effect properly This led to the development of radically new theory( Quantum Mechanics) to deal with atomic and molecular phenomena.
Physics deals with the combination of matter and energy. It also deals with a wide variety of systems, about which theories have been developed that are used by physicists. In general, theories are experimentally tested numerous times before they are accepted as correct as a description of Nature (within a certain domain of validity). For instance, the theory of classical mechanics accurately describes the motion of objects, provided they are much larger than atoms and moving at much less than the speed of light. These "central theories" are important tools for research in more specialized topics, and any physicist, regardless of his or her specialization, is expected to be literate in them.
