Physics is the branch of science that deals with the study of natural phenomena in terms of basic laws and physical quantities. The scope of physics is divided into two major domains: macroscopic and microscopic. The macroscopic domain deals with phenomena at laboratory, realistic, terrestrial and astronomical scale, whereas the microscopic domain deals with molecular, atomic and nuclear phenomena.
The physical world is a manifestation of some universal laws in different domains and with the required conditions applicable as per the contexts. We derive the properties of bigger or more complex system from the properties or interaction of the simpler parts or constituents of the system. This approach is called reductionism and helps in understanding the properties of complex systems in physics like functioning of satellites, etc.
Physics is closely connected to technology and society. Most of the modern technologies are contributions from the realm of physics and work on one or the other scientific principle. These contributions came from all over the world, through observations, experimentation or analysis of natural phenomena and the rules or laws that govern such phenomena. These gave us the knowledge of fundamental forces in nature and physical laws.
There are four fundamental forces in nature and all other forces we know are derived from these forces. They are gravitational force, electromagnetic force, weak nuclear force and strong nuclear force.
The gravitational force is the force of mutual attraction between any two objects by virtue of their masses. Electromagnetic force is the force between two charged particles. The force that binds the protons and the neutrons in the nucleus of an atom is the strong nuclear force. Weak nuclear force comes into existence in case of beta-decay of a nucleus. In beta-decay, the nucleus emits an electron and an uncharged particle called neutrino.
Scientific generalizations based on physicist’s observations and experiments are presented as laws or empirical relations in form of mathematical equations, known as physical laws. Most of these laws are based on some special quantities that remain unchanged in a process, which are known as conserved quantities. Some of the general conservation laws in nature include the laws of conservation of mass, energy, linear momentum, angular momentum, charge, parity, etc.