Theory of Relativity Introduction- Lecture-1

Theory of Relativity - Lecture-1

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1.Introduction: We are familiar with the word 'motion'. In every day life we see the motion of several objects around us. If we have been asked to define motion we would say “change of position with time”. In an attempt to define motion we have used two concepts space (position) and time. By our intuition, we know what is space and time and these are defined as follows according to Newton's view. Space is absolute, in the sense that it exists permanently and independently whether any matter in the space or moving through it. Thus space is a sort of three dimensions matrix into which one can place objects or through which objects can move without producing any interaction between space and object. Each object in the universe exists at a particular point in space at a particular time. An object in motion undergoes continuous change of position with time. Time in Newton's view is also absolute and flows on without regard to any physical object or event. One can neither speed up the time nor slow down its rate. The flow of time exists uniformly through the universe. If we imagine the instant 'now', it occurs simultaneously on every planet and star in the universe. The time interval between two events is same everywhere in the universe, it can be verified by observing of physical, chemical and biological events. We have defined space and time, with our everyday knowledge about nature and surroundings. However there are some contradictions with our intuition, when the motion of an object is at very high speed, approaching or equaling the speed of light. It was Einstein who exposed some of the most important limitations of classical ideas including that of Newton. Einstein contribution led to the development of special theory of relativity (STR).