What is physics?

Physics is the study of nature and natural phenomena. Physicists try to discover the rules that are operating in nature, on the basis of observations, experimentation and analysis. Physics deals with certain basic rules/laws governing the natural world.

Physics is a basic discipline in the category of Natural Science, which also includes other disciplines like Chemistry and Biology. The word Physics comes from a Greek word meaning nature. Its Sanskrit equivalent is Bhautiki that is used to refer to the study of the physical world. A precise definition of this discipline is neither possible nor necessary. We can broadly describe physics as a study of the basic laws of nature and their manifestation in different natural phenomena. Here we remark on two principal thrusts in physics : unification and reduction.

In Physics, we attempt to explain diverse physical phenomena in terms of a few concepts and laws. The effort is to see the physical world as manifestation of some universal laws in different domains and conditions. For, example, the same law of gravitation describes the fall of an apple to the ground, the motion of the moon around the earth and the motion of planets around the sun. Similarly, the basic laws of electromagnetism ( Maxwell's equations) govern all electric and magnetic phenomena. The attempt to unify fundamental forces of nature reflect this same quest for unification.

A related effort is to derive the properties of a bigger, more complex, system from the properties and interactions of it's constituent simpler parts. This approach is called reductionism and is at the heart of physics. For example, the subject of thermodynamics, developed in the nineteenth century, deals with bulk systems in terms of macroscopic quantities such as temperature, internal energy, entropy, etc. Subsequently, the subjects of kinetic theory and statistical mechanics interpreted these quantities in terms of the properties of the molecular constituents of the bulk system. In particular, the temperature was seen to be related to the average kinetic energy of molecules of the system.